Alloy aluminum foil for lithium battery and manufacturing method thereof

Abstract

The invention provides an alloy aluminum foil for a lithium battery and a manufacturing method thereof, and relates to the technical field of aluminum-based alloys, electrolytic aluminum water is adopted as a raw material for smelting and casting, the alloy aluminum foil comprises the following components in percentage by mass: 0.30-0.50% of Fe, 0.07-0.12% of Si, 0.01-0.04% of Cu, 0.01-0.03% of Ti, 0.01-0.03% of Zr, less than or equal to 0.01% of Mn, less than or equal to 0.005% of Mg, less than or equal to 0.005% of Zn, 0-0.10% of Dy, 0-0.10% of Ho and 0-0.10% of Y, the sum of the mass percentages of Dy, Ho and Y is 0.01-0.20%, rare earth elements are added in the form of dysprosium iron, holmium iron and yttrium iron metals, and the balance of aluminum the rare earth element accounts for 50-80% of the alloy; the balance is Al and inevitable impurities; wherein the mass ratio of Fe to Si is 2.5-4.0, and the total content of Fe and Si is less than or equal to 0.38%. The surface wetting tension and the mechanical property of the aluminum foil are improved by limiting the Fe / Si ratio to be 2.5-4.0 and controlling Fe + Si to be smaller than or equal to 0.38%, adding dysprosium iron, holmium iron and yttrium iron to control 50-80% of rare earth, generating a nano precipitated phase through hot rolling annealing, controlling the grain size to be smaller than or equal to grade 1, performing double-rack cold continuous rolling ply rolling to 0.009-0.012 mm, and regulating the annealing strip speed and the injection pressure.

Description

Technical Field

[0001] This invention relates to the field of aluminum-based alloy technology, and in particular to an alloy aluminum foil for lithium batteries and its manufacturing method. Background Technology

[0002] The field of aluminum-based alloy technology encompasses research and applications in energy materials, packaging materials, and structural materials. The core of this technology involves the alloying process of aluminum with other metallic elements. Using electrolytic aluminum as raw material, different aluminum alloy materials with varying properties are obtained through elemental composition ratios, controlled smelting processes, and subsequent rolling and heat treatment. At a systemic level, aluminum-based alloy technology covers smelting and refining processes, casting methods, hot and cold rolling processes, annealing, and surface treatment steps to ensure that the materials meet specific application requirements in terms of strength, ductility, conductivity, and corrosion resistance. Research and development in this field also extend to specific applications in new energy, energy storage devices, and lightweight structures; therefore, the manufacturing methods of aluminum-based alloy materials have become a core foundation for related industries.

[0003] One of the patents, an alloy aluminum foil for lithium batteries, refers to aluminum alloy sheet materials used in the negative electrode or current collector of lithium batteries and their preparation process. This patent primarily covers the selection and content control of alloying elements, aluminum ingot smelting and casting, obtaining the required thickness through hot and cold rolling, annealing to improve microstructure uniformity, and surface treatment to enhance bonding performance with electrode materials. Its manufacturing method typically involves precise composition design, melt purification and homogenization treatment, step-by-step rolling processes, and specific annealing temperature and time control to ensure that the alloy aluminum foil possesses the necessary characteristics for lithium battery applications.

[0004] Existing technologies offer a wide range of control over component ratios, which can easily lead to coarse and uneven morphology of the Fe and Si phases, resulting in localized stress concentration points on the surface and increasing the likelihood of pinhole formation. Insufficient control over hydrogen content during the casting stage means that micropore defects remain after rolling, affecting the density of the foil. Soaking processes are often limited to a single temperature range, resulting in insufficient diffusion of alloying elements and significant differences in grain and second-phase distribution, leading to microstructural instability. The lack of parameter matching in the annealing and rolling processes results in fluctuations in surface roughness and smoothness, and unstable conductivity. These shortcomings make it difficult for aluminum foil to meet high consistency requirements in terms of thickness uniformity, microstructural stability, and surface wettability. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems mentioned in the background section.

[0006] The present invention adopts the following technical solution: an alloy aluminum foil for lithium batteries, which is smelted and cast using electrolytic aluminum as raw material, and contains the following components by mass percentage: Fe: 0.30~0.50%, Si: 0.07~0.12%, Cu: 0.01~0.04%, Ti: 0.01~0.03%, Zr: 0.01~0.03%, Mn≤0.01%, Mg≤0.005%, Zn≤0.005%, Dy: 0~0.10%, Ho: 0~0.10%, Y: 0~0.10%, and the sum of the mass percentages of Dy, Ho and Y is 0.01~0.20%. Rare earth elements are added in the form of dysprosium iron, holmium iron and yttrium iron metals, and the proportion of rare earth elements in the alloy is 50~80%; the remainder is Al and unavoidable impurities; wherein the Fe / Si mass ratio is 2.5~4.0, and the total Fe+Si content is ≤0.38%.

[0007] Preferably, the physical properties of the aluminum foil are: thickness 0.009~0.012mm, tensile strength 180~210MPa, elongation 4~6%, and pinhole rate not exceeding 0.1 pins / m. 2 Conductivity ≥63% IACS.

[0008] Preferably, the microstructure of the aluminum foil is as follows: the grain size of the cold-rolled billet is ≤ grade 1 according to GB / T3246.1 standard, the grain size deviation is ≤ 5μm, the grains are equiaxed or approximately equiaxed, the second phase Al3Fe particles are ≤ 2μm in size and are uniformly and stably distributed, and the α solid solution and Al(FeSi) α and β phases are uniformly distributed.

[0009] Preferably, the surface properties of the aluminum foil are: surface wetting tension ≥35dyn / cm, suitable for water-based and oil-based electrode paste systems; flatness of the finished strip with a sag of ≤3mm under a 6N horizontal force; surface roughness Ra≤0.8μm, Rz≤6μm.

[0010] Preferably, the alloy composition improves the adhesion between the aluminum foil and the electrode paste through the following mechanism: The Al3Fe and Al(FeSi) second-phase particles formed by Fe and Si elements are uniformly distributed on the aluminum foil surface. The particle size is ≤2μm. The microscopic protrusions increase the surface roughness and provide mechanical anchoring, which improves the adhesion by 15~25% compared with pure aluminum. Cu exists in a solid solution state, which improves the surface wetting properties of aluminum foil, reduces the contact angle with electrode paste by 5~10°, and enhances chemical bonding. Ti and Zr elements refine the grain structure to ≤1 level, forming a uniform and dense surface structure, eliminating surface defects caused by coarse grains, and improving the uniformity of interfacial bonding. Rare earth elements Dy, Ho, and Y regulate the surface energy of aluminum foil through solid solution strengthening and precipitation strengthening mechanisms, so that the surface wetting tension reaches ≥35dyn / cm, thus optimizing the compatibility with water-based and oil-based electrode pastes. The Fe / Si mass ratio is controlled within the range of 2.5 to 4.0 to ensure the optimal morphological ratio of the second phase Al3Fe and the Al phase, and to avoid surface inhomogeneity caused by coarse second phase. Through the synergistic effect of the above components, the adhesion between the aluminum foil and the electrode paste reaches ≥2.0 N / cm.

[0011] A method for manufacturing alloy aluminum foil for lithium batteries employs a production process of "melting and casting flat ingots + integrated homogenization heating + 1+3 hot continuous rolling + double-stand cold continuous rolling + air cushion furnace online rapid annealing + foil rolling", including the following steps: S1: Alloy smelting and casting: According to the alloy element composition requirements, control the contents of Fe, Si, Cu, Ti, Zr, rare earth elements, etc., smelting temperature 730~740℃, add Al-5Ti-0.2B grain refiner 0.1~0.3%, adopt DC casting, casting temperature 690~700℃, ingot hydrogen content ≤0.12 ml / 100g·Al; S2: Homogenization treatment: After milling the ingot surface, it is heated and homogenized in one piece. The first homogenization temperature is 450~470℃, and the second homogenization temperature is 520~540℃. S3: Hot continuous rolling: hot roughing and 1+3 stand hot finishing rolling, with a final rolling temperature of 390~410℃; S4: Cold continuous rolling and intermediate heat treatment: First double-stand cold continuous rolling to 2.0~2.2mm, air cushion furnace heat treatment temperature 440~470℃, belt speed 35~45m / min, spray pressure 0.15~0.25MPa, water cooling, grain control ≤1 level; S5: Finishing and Foil Rolling: The second double-stand cold continuous rolling is rolled to 0.4~0.5mm, using a stacking rolling process, with a single pass reduction of 40~55%, and finally rolled into finished aluminum foil rolls with a thickness of 0.009~0.012mm; S6: Slitting, Inspection and Packaging: The finished aluminum foil rolls are first slitting according to the preset specifications. After slitting, the number of pinholes, conductivity, plate shape, uniformity of grain structure and surface quality of the aluminum foil are comprehensively inspected. After all performance indicators are confirmed to be qualified, the aluminum foil rolls are sealed and packaged.

[0012] Preferably, the process improves the uniformity of aluminum foil structure through the following technical means: The heat conduction finite element analysis of the ingot homogenization and heating process was performed using Flowmaster numerical analysis software; the deformation parameters of the hot rolling and cold rolling processes were optimized; the formation and distribution of Al(FeSi) α and β phases were controlled, and the homogenization degree of α solid solution was ≥95%.

[0013] Preferably, in step S2: the first-stage heat equalization temperature of the integrated heating and heat equalization is 450~470℃ and the heat equalization time is 8h; the second-stage heat equalization temperature is 520~540℃ and the heat equalization time is 12h.

[0014] Preferably, the manufacturing process optimizes adhesion by controlling the distribution of alloying elements and the morphology of the second phase: The homogenization process controls the diffusion of Fe and Si elements to ensure uniform precipitation of Al3Fe and Al phases. The hot continuous rolling temperature of 390~410℃ ensures that Cu is adequately dissolved and that Ti and Zr fully play their grain-refining role. The air cushion furnace heat treatment process causes rare earth elements Dy, Ho, and Y to form nanoscale precipitates, improving the surface microstructure. The deformation and distribution of second-phase particles during cold rolling and foil rolling processes create microscopic morphological features on the aluminum foil surface that are conducive to adhesion.

[0015] Preferably, the conductivity of the aluminum foil is optimized by controlling the dislocation density in the crystal lattice structure to be ≤10. 12 / cm 2 This reduces lattice distortion caused by solid solution elements, optimizes the size and distribution of second-phase particles, and enables the material to achieve an conductivity of 63-67% IACS.

[0016] Compared with the prior art, the advantages and positive effects of the present invention are as follows: In this invention, by limiting the Fe / Si mass ratio to 2.5-4.0 and controlling the total Fe+Si content to ≤0.38%, the second phase particles are made fine and uniform, avoiding the aggregation of coarse phases. By adding dysprosium, holmium, yttrium, and iron, the rare earth content is controlled to be 50-80%. Combined with hot rolling and online annealing, nanoscale precipitates are formed, promoting a dense grain structure with a grain size ≤1 grade. The thickness is gradually reduced to 0.009-0.012 mm using a twin-stand cold continuous rolling and stack rolling method. At the same time, the belt speed and spray pressure are controlled during the gas cushion furnace annealing process to increase the surface wetting tension, resulting in uniform roughness and stable plate shape. By reducing the hydrogen content in the ingot and using graded homogenization diffusion, the pinhole rate is reduced, and the conductivity is increased to 63-67% IACS. Attached Figure Description

[0017] Figure 1 This invention provides a process flow diagram for manufacturing alloy aluminum foil for lithium batteries; Figure 2Metallographic image of the surface of the finished 0.012mm thick 1060 aluminum foil of this invention -100X-p6s-f60s; Figure 3 This is a surface grain diagram of the 1060 aluminum foil cold-rolled billet (after intermediate heat treatment in an air cushion furnace) of the present invention -100X-p6s-f60s-. Detailed Implementation

[0018] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0019] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0020] This invention provides a technical solution: an alloy aluminum foil for lithium batteries, smelted and cast using electrolytic aluminum molten material, comprising the following components by mass percentage: Fe: 0.30~0.50%, Si: 0.07~0.12%, Cu: 0.01~0.04%, Ti: 0.01~0.03%, Zr: 0.01~0.03%, Mn≤0.01%, Mg≤0.005%, Zn≤0.005%, Dy: 0~0.10%, Ho: 0~0.10%, Y: 0~0.10%, and the sum of the mass percentages of Dy, Ho, and Y is 0.01~0.20%. Rare earth elements are added in the form of dysprosium iron, holmium iron, and yttrium iron metals, with rare earth elements accounting for 50~80% of the alloy; the remainder is Al and unavoidable impurities; wherein the Fe / Si mass ratio is 2.5~4.0, and the total Fe+Si content is ≤0.38%.

[0021] The physical properties of the aluminum foil are as follows: thickness 0.009~0.012mm, tensile strength 180~210MPa, elongation 4~6%, and pinhole rate not exceeding 0.1 pins / m. 2 Conductivity ≥63% IACS; The microstructure characteristics of the aluminum foil are as follows: the grain size of the cold-rolled billet is ≤ grade 1 according to GB / T3246.1 standard, the grain size deviation is ≤ 5μm, the grains are equiaxed or approximately equiaxed, the second phase Al3Fe particles are ≤ 2μm in size and are uniformly and stably distributed, and the α solid solution and Al(FeSi) α and β phases are uniformly distributed. The surface properties of the aluminum foil are as follows: surface wetting tension ≥35dyn / cm, suitable for water-based and oil-based electrode paste systems; flatness of the finished strip with a sag of ≤3mm under a 6N horizontal force; surface roughness Ra≤0.8μm, Rz≤6μm; The alloy composition improves the adhesion between the aluminum foil and the electrode paste through the following mechanisms: The Al3Fe and Al(FeSi) second-phase particles formed by Fe and Si elements are uniformly distributed on the aluminum foil surface. The particle size is ≤2μm. The microscopic protrusions increase the surface roughness and provide mechanical anchoring, which improves the adhesion by 15~25% compared with pure aluminum. Cu exists in a solid solution state, which improves the surface wetting properties of aluminum foil, reduces the contact angle with electrode paste by 5~10°, and enhances chemical bonding. Ti and Zr elements refine the grain structure to ≤1 level, forming a uniform and dense surface structure, eliminating surface defects caused by coarse grains, and improving the uniformity of interfacial bonding. Rare earth elements Dy, Ho, and Y regulate the surface energy of aluminum foil through solid solution strengthening and precipitation strengthening mechanisms, so that the surface wetting tension reaches ≥35dyn / cm, thus optimizing the compatibility with water-based and oil-based electrode pastes. The Fe / Si mass ratio is controlled within the range of 2.5 to 4.0 to ensure the optimal morphological ratio of the second phase Al3Fe and the Al phase, and to avoid surface inhomogeneity caused by coarse second phase. Through the synergistic effect of the above components, the adhesion between the aluminum foil and the electrode paste reaches ≥2.0 N / cm; A method for manufacturing alloy aluminum foil for lithium batteries employs a production process of "melting and casting flat ingots + integrated homogenization heating + 1+3 hot continuous rolling + double-stand cold continuous rolling + air cushion furnace online rapid annealing + foil rolling", including the following steps: S1: Alloy smelting and casting: According to the alloy element composition requirements, control the contents of Fe, Si, Cu, Ti, Zr, rare earth elements, etc., smelting temperature 730~740℃, add Al-5Ti-0.2B grain refiner 0.1~0.3%, adopt DC casting, casting temperature 690~700℃, ingot hydrogen content ≤0.12 ml / 100g·Al; S2: Homogenization treatment: After milling the ingot surface, it is heated and homogenized in one piece. The first homogenization temperature is 450~470℃, and the second homogenization temperature is 520~540℃. S3: Hot continuous rolling: hot roughing and 1+3 stand hot finishing rolling, with a final rolling temperature of 390~410℃; S4: Cold continuous rolling and intermediate heat treatment: First double-stand cold continuous rolling to 2.0~2.2mm, air cushion furnace heat treatment temperature 440~470℃, belt speed 35~45m / min, spray pressure 0.15~0.25MPa, water cooling, grain control ≤1 level; S5: Finishing and Foil Rolling: The second double-stand cold continuous rolling is rolled to 0.4~0.5mm, using a stacking rolling process, with a single pass reduction of 40~55%, and finally rolled into finished aluminum foil rolls with a thickness of 0.009~0.012mm; S6: Slitting, Inspection and Packaging: The finished aluminum foil rolls are first slitting according to the preset specifications. After slitting, the number of pinholes, conductivity, plate shape, uniformity of grain structure and surface quality of the aluminum foil are comprehensively inspected. After all performance indicators are confirmed to be qualified, the aluminum foil rolls are sealed and packaged. The process improves the uniformity of aluminum foil structure through the following technical means: The heat conduction finite element analysis of the ingot homogenization and heating process was performed using Flowmaster numerical analysis software; the deformation parameters of the hot rolling and cold rolling processes were optimized; the formation and distribution of Al(FeSi) α and β phases were controlled, and the homogenization degree of α solid solution was ≥95%. In step S2: the first-stage heat equalization temperature of the integrated heating system is 450~470℃ and the holding time is 8h; the second-stage heat equalization temperature is 520~540℃ and the holding time is 12h. The manufacturing process optimizes adhesion by controlling the distribution of alloying elements and the morphology of the second phase. The homogenization process controls the diffusion of Fe and Si elements to ensure uniform precipitation of Al3Fe and Al phases. The hot continuous rolling temperature of 390~410℃ ensures that Cu is adequately dissolved and that Ti and Zr fully play their grain-refining role. The air cushion furnace heat treatment process causes rare earth elements Dy, Ho, and Y to form nanoscale precipitates, improving the surface microstructure. The deformation and distribution of second-phase particles during cold rolling and foil rolling processes form microscopic morphological features on the aluminum foil surface that are conducive to adhesion. The conductivity of the aluminum foil was optimized by controlling the dislocation density in the crystal lattice structure to be ≤10. 12 / cm 2 This reduces lattice distortion caused by solid solution elements, optimizes the size and distribution of second-phase particles, and enables the material to achieve an conductivity of 63-67% IACS. Example 1 S1: Electrolytic aluminum molten metal is formulated with the following composition (Fe: 0.32%, Si: 0.08%, Cu: 0.02%, Ti: 0.02%, Zr: 0.02%, Dy: 0.05%, Ho: 0.03%, Y: 0.02%), refined at 735℃, and cast using DC casting (temperature 695℃, with the addition of 0.2% Al-5Ti-0.2B). The hydrogen content of the ingot is 0.10 ml / 100 g Al. S2: After milling, integrated heat homogenization is performed (first stage 460℃×8h, second stage 530℃×12h), and the microstructure uniformity coefficient reaches 0.95; S3: Hot roughing reduction of 38%, hot finishing rolling temperature of 400℃ on 1+3 stand, cold continuous rolling to 2.1mm and then sent to air cushion furnace (450℃, belt speed 40m / min, spray pressure 0.20MPa, water cooling), grain size grade 1; S4: Secondary cold continuous rolling to 0.45mm, foil rolling reduction of 48%, finished product thickness of 0.011mm; S5: Pinhole rate after slitting is 0.08 pinholes / m 2 Tensile strength 195MPa, elongation 5.2%, conductivity 64.2%IACS, surface wetting tension 38.5dyn / cm, adhesion 2.3N / cm, plate shape 3I; Example 2 S1: Electrolytic aluminum molten metal was formulated with the following composition (Fe: 0.28%, Si: 0.10%, Cu: 0.03%, Ti: 0.03%, Zr: 0.03%, Dy: 0.08%, Ho: 0.05%, Y: 0.07%), refined at 740℃, and cast using DC casting (700℃, with the addition of 0.3% Al-5Ti-0.2B). The hydrogen content of the ingot was 0.09 ml / 100 g Al. S2: After milling, integrated heat homogenization is performed (first stage 470℃×8h, second stage 540℃×12h), and the microstructure uniformity coefficient reaches 0.97; S3: Hot roughing reduction of 40%, hot finishing rolling temperature of 410℃ on 1+3 stand, cold continuous rolling to 2.0mm and then sent to air cushion furnace (470℃, belt speed 45m / min, spray pressure 0.25MPa, water cooling), grain size grade 1; S4: Secondary cold continuous rolling to 0.40mm, foil rolling reduction of 55%, finished product thickness of 0.010mm; S5: Pinhole rate after slitting is 0.06 pinholes / m 2 Tensile strength 205MPa, elongation 4.8%, conductivity 63.8%IACS, surface wetting tension 40.2dyn / cm, adhesion 2.6N / cm, plate shape 2I; Example 3 S1: Electrolytic aluminum molten metal was formulated with the following composition (Fe: 0.35%, Si: 0.12%, Cu: 0.04%, Ti: 0.01%, Zr: 0.01%, Dy: 0.04%, Ho: 0.02%, Y: 0.01%), refined at 730℃, and cast using DC casting (temperature 690℃, with the addition of 0.1% Al-5Ti-0.2B). The hydrogen content of the ingot was 0.12 ml / 100 g Al. S2: After milling, integrated heat homogenization is performed (first stage 450℃×8h, second stage 520℃×12h), and the microstructure uniformity coefficient reaches 0.94; S3: Hot roughing reduction of 35%, hot finishing rolling temperature of 390℃ on 1+3 stand, cold continuous rolling to 2.2mm and then sent to air cushion furnace (440℃, belt speed 35m / min, spray pressure 0.15MPa, water cooling), grain size grade 1; S4: Secondary cold continuous rolling to 0.50mm, foil rolling reduction of 40%, finished product thickness 0.012mm; S5: Pinhole rate after slitting is 0.09 pinholes / m 2 Tensile strength 188MPa, elongation 5.5%, conductivity 65.1%IACS, surface wetting tension 36.8dyn / cm, adhesion 2.1N / cm, plate shape 4I; Comparative Example Comparative Example 1 S1: Fe: 0.35%, Si: 0.25%, Cu: 0.05%, refining temperature 750℃, DC casting (temperature 710℃, no refining agent added), ingot hydrogen content 0.18ml / 100g·Al; S2: The uniform heating temperature of the box furnace is 480℃×6h, and the microstructure uniformity coefficient is 0.78; S3: Conventional hot finishing rolling temperature 430℃, box furnace annealing (500℃×4h, furnace cooling), grain size grade 3; S4: Traditional cold rolling + foil rolling, reduction 25%, finished product thickness 0.012mm; S5: Pinhole rate 0.25 / m 2 Tensile strength 165MPa, elongation 2.8%, conductivity 61.5%IACS, surface wetting tension 32.1dyn / cm, adhesion 1.5N / cm, plate shape 12I; Comparative Example 2 S1: Fe: 0.20%, Si: 0.10%, Cu: 0.02%, refining temperature 735℃, DC casting (temperature 695℃, 0.2% Al-5Ti-0.2B added), ingot hydrogen content 0.11ml / 100g·Al; S2: Homogenization temperature 500℃×8h, tissue uniformity coefficient 0.85; S3: Hot finishing rolling temperature 400℃, air cushion furnace heat treatment (450℃, belt speed 40m / min, water cooling), grain size grade 2; S4: Foil rolling reduction 45%, finished product thickness 0.011mm; S5: Pinhole rate 0.18 / m 2Tensile strength 158MPa, elongation 3.2%, conductivity 62.8%IACS, surface wetting tension 33.5dyn / cm, adhesion 1.7N / cm; Comparative Example 3 S1: Fe: 0.40%, Si: 0.20%, Cu: 0.03%, refining temperature 740℃, DC casting (temperature 700℃, 0.2% Al-5Ti-0.2B added), ingot hydrogen content 0.13ml / 100g·Al; S2: Homogenization temperature 520℃×10h, tissue uniformity coefficient 0.82; S3: Hot finishing rolling temperature 390℃, air cushion furnace heat treatment (460℃, belt speed 38m / min, water cooling), grain size grade 4; S4: Foil rolling reduction 42%, finished product thickness 0.011mm; S5: Pinhole rate 0.35 / m 2 Tensile strength 145MPa, elongation 2.1%, conductivity 59.2%IACS, surface wetting tension 31.8dyn / cm, adhesion 1.2N / cm; Comparative Example 4 S1: Fe: 0.25%, Si: 0.15%, Cu: 0.02%, refining temperature 735℃, DC casting (temperature 695℃, 0.2% Al-5Ti-0.2B added), ingot hydrogen content 0.12ml / 100g·Al; S2: Homogenization temperature 510℃×8h, tissue uniformity coefficient 0.88; S3: Hot finishing rolling temperature 395℃, air cushion furnace heat treatment (455℃, belt speed 42m / min, water cooling), grain size grade 2; S4: Foil rolling reduction 46%, finished product thickness 0.010mm; S5: Pinhole rate 0.22 / m 2 Tensile strength 172MPa, elongation 3.8%, conductivity 60.5%IACS, surface wetting tension 34.2dyn / cm, adhesion 1.8N / cm; The alloy aluminum foils prepared in Examples 1, 2, and 3 and Comparative Examples 1-3 were tested, and the test results are as follows:

[0022] Based on the test results in the table above, this invention, by optimizing the alloy composition ratios of Fe, Si, Cu, Ti, Zr, and rare earth elements Dy, Ho, and Y, and combining it with an advanced manufacturing process of "1+3 hot continuous rolling + twin-stand cold continuous rolling + air cushion furnace online rapid annealing + foil rolling," significantly outperforms traditional aluminum foil and existing lithium battery aluminum foil materials in key performance indicators such as tensile strength, elongation, pinhole rate, conductivity, surface wetting tension, and adhesion. Specifically: 1. Significantly improved mechanical properties: tensile strength reaches 188-205MPa, an increase of 13.8-41.4% compared to the comparative example; elongation reaches 4.8-5.5%, an increase of 26.3-161.9% compared to the comparative example, achieving a good match between strength and plasticity.

[0023] 2. Excellent conductivity: The conductivity reaches 63.8-65.1% IACS, which is 2.0-10.0% higher than the comparative ratio, meeting the stringent requirements of high-performance lithium batteries for the conductivity of current collectors.

[0024] 3. Significantly improved surface quality: pinhole rate reduced to 0.06-0.09 pins / m 2 Compared with the control, the surface wetting tension was reduced by 67.5-85.7%; the surface wetting tension was increased to 36.8-40.2 dyn / cm, which was 8.1-26.4% higher than the control; and the adhesion reached 2.1-2.6 N / cm, which was 16.7-73.3% higher than the control.

[0025] 4. Microstructure optimization: The grain size reached level 1, and the microstructure uniformity coefficient reached 0.94-0.97, which is significantly better than the comparative example of 0.78-0.88, ensuring the stability and consistency of material properties.

[0026] Therefore, the alloy aluminum foil of the present invention fully meets the technical requirements of high strength, high conductivity, low pinhole rate and strong adhesion for the positive electrode current collector of new energy vehicle power batteries.

[0027] Based on the aforementioned elements and the characteristics of aluminum foil, a 50-100 nm thick titanium oxide or chromium oxide coating is applied to the aluminum foil surface. Active groups such as amino and carboxyl groups are introduced using molecular self-assembly technology. Then, a low-temperature, low-pressure plasma treatment technique is employed to form a nanoscale rough structure on the coating surface, increasing the surface contact area and the density of chemical groups. Next, the interfacial adhesion strength is measured through tensile, shear strength, and corrosion resistance tests to optimize the coating thickness and plasma treatment time parameters. Subsequently, the optimized aluminum foil-anode material assembly undergoes long-term charge-discharge cycle testing to evaluate capacity decay and interfacial stability. Finally, the cycle performance decay is analyzed to assess the effectiveness of this optimization method in improving battery performance and the degree of improvement in interfacial stability.

[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An alloyed aluminum foil for lithium batteries, characterized by: The alloy is smelted and cast by using electrolytic aluminum water as raw material, and contains the following components in percentage by mass: Fe: 0.30-0.50%, Si: 0.07-0.12%, Cu: 0.01-0.04%, Ti: 0.01-0.03%, Zr: 0.01-0.03%, Mn≤0.01%, Mg≤0.005%, Zn≤0.005%, Dy: 0-0.10%, Ho: 0-0.10%, Y: 0-0.10%, and the sum of the percentages by mass of Dy, Ho and Y is 0.01-0.20%, the rare earth elements are added in the form of dysprosium iron, holmium iron and yttrium iron metal, the rare earth elements account for 50-80% in the alloy, and the rest is Al and inevitable impurities; wherein the mass ratio of Fe / Si is 2.5-4.0, and the total content of Fe+Si is ≤0.38%.

2. The alloyed aluminum foil for lithium batteries according to claim 1, characterized by: The physical performance parameters of the aluminum foil are: thickness 0.009-0.012 mm, tensile strength 180-210 MPa, elongation 4-6%, pinhole rate not more than 0.1 / m, and conductivity ≥63%IACS. 2 ​ 3. The alloyed aluminum foil for lithium batteries according to claim 1, characterized in that: The microstructure features of the aluminum foil are as follows: the grain size of the cold-rolled base material is ≤1 level according to GB / T3246.1 standard, the grain size deviation is ≤5 μm, the grains are equiaxed or approximately equiaxed, the size of the second phase Al3Fe particles is ≤2 μm and the distribution is uniform and stable, and the α solid solution and Al(FeSi)α phase and β phase are uniformly distributed.

4. The alloyed aluminum foil for lithium batteries according to claim 1, characterized by: The surface performance of the aluminum foil is as follows: the surface wetting tension is ≥35 dyn / cm, which is suitable for water-based and oil-based electrode paste systems; the flatness of the finished strip is ≤3 mm under the action of a 6N horizontal force; the surface roughness Ra is ≤0.8 μm, and Rz is ≤6 μm.

5. The alloyed aluminum foil for lithium batteries according to claim 1, characterized in that: The alloy composition improves the adhesion of the aluminum foil to the electrode paste through the following mechanisms: The Al3Fe and Al(FeSi) second phase particles formed by Fe and Si elements are uniformly distributed on the surface of the aluminum foil, the particle size is ≤2 μm, the surface roughness is increased through micro-protrusions, mechanical anchoring is provided, and the adhesion is increased by 15-25% compared with pure aluminum; The Cu element exists in a solid solution state, improves the wetting properties of the aluminum foil surface, reduces the contact angle with the electrode paste by 5-10°, and enhances the chemical bonding force; Ti and Zr elements refine the grain structure to ≤1 level, form a uniform and dense surface structure, eliminate surface defects caused by coarse grains, and improve the uniformity of the interface bonding; The rare earth elements Dy, Ho and Y adjust the surface energy of the aluminum foil through solid solution strengthening and precipitation strengthening mechanisms, so that the surface wetting tension reaches ≥35 dyn / cm, and the compatibility with water-based and oil-based electrode pastes is optimized; The mass ratio of Fe / Si is controlled in the range of 2.5-4.0, the best morphological ratio of the second phase Al3Fe and Al is ensured, and surface unevenness caused by coarse second phase is avoided; Through the synergistic effect of the above-mentioned components, the adhesion of the aluminum foil to the electrode paste reaches ≥2.0 N / cm.

6. A method for producing an alloyed aluminum foil for lithium batteries, characterized by: The method is used to realize the alloy aluminum foil for lithium batteries in any one of claims 1-5, adopts a production process of "smelting and casting flat ingot + integrated soaking heating + 1+3 hot continuous rolling + double rack cold continuous rolling + air cushion furnace online rapid annealing + foil rolling", and includes the following steps: S1: Alloy smelting and casting: according to the alloy element component requirements, using electrolytic aluminum water as raw material, controlling the content of Fe, Si, Cu, Ti, Zr, rare earth elements, etc., the smelting temperature is 730~740℃, adding Al-5Ti-0.2B grain refiner 0.1~0.3%, using DC casting, the casting temperature is 690~700℃, the hydrogen content of the ingot is ≤0.12 ml / 100g·Al; S2: homogenization treatment: after the ingot milling, integrated heating and soaking, the first stage soaking temperature is 450~470℃, the second stage soaking temperature is 520~540℃; S3: hot continuous rolling: hot rough rolling and 1+3 rack hot finishing rolling are carried out, and the finish rolling temperature is 390~410℃; S4: cold continuous rolling and intermediate heat treatment: the first double rack cold continuous rolling is carried out to 2.0~2.2mm, the heat treatment temperature of the air cushion furnace is 440~470℃, the strip speed is 35~45m / min, the jet pressure is 0.15~0.25MPa, water cooling, and the grain control is ≤1 level; S5: finishing rolling and foil rolling: the second double rack cold continuous rolling is carried out to 0.4~0.5mm, the stacking process is adopted, the single pass reduction is 40~55%, and finally the finished aluminum foil roll with a thickness of 0.009~0.012mm is obtained; S6: slitting, detecting and packaging: the finished aluminum foil roll is first cut according to the preset specifications, and then the pinhole number, conductivity, plate shape state, grain organization uniformity and surface quality of the aluminum foil are comprehensively detected; after the performance indicators are confirmed to be qualified, the aluminum foil roll is sealed and packaged.

7. The alloyed aluminum foil manufacturing method for lithium batteries according to claim 6, characterized in that: The process improves the uniformity of the aluminum foil by the following technical means: The Flowmaster numerical analysis software is used to analyze the heat conduction finite element of the ingot soaking and heating process; the deformation parameters of the hot continuous rolling and cold rolling process are optimized; the formation and distribution of Al(FeSi)α phase and β phase are controlled, and the homogenization degree of α solid solution is ≥95%.

8. The alloyed aluminum foil manufacturing method for lithium batteries according to claim 6, characterized in that: In the S2 step: the first stage soaking temperature of the integrated heating and soaking is 450~470℃, and the holding time is 8h; the second stage soaking temperature is 520~540℃, and the holding time is 12h.

9. The alloyed aluminum foil manufacturing method for lithium batteries according to claim 6, characterized in that: The manufacturing process optimizes the adhesion by controlling the distribution of alloy elements and the second phase morphology: The diffusion of Fe and Si elements is controlled in the homogenization treatment stage, so that Al3Fe phase and Al phase are uniformly precipitated; The Cu element is moderately solid-solved, and the Ti and Zr elements fully play the grain refinement role at the finish rolling temperature of 390~410℃ in the hot continuous rolling; The nanoscale precipitated phase of rare earth elements Dy, Ho and Y is formed by the air cushion furnace heat treatment process, which improves the surface microstructure; The deformation and distribution of the second phase particles in the cold rolling and foil rolling process form the microtopography features conducive to adhesion on the surface of the aluminum foil.

10. The alloyed aluminum foil manufacturing method for lithium batteries according to claim 6, characterized in that: The conductivity of the aluminum foil is optimized by controlling the dislocation density in the lattice structure to be ≤10 12 / cm 2 , reducing the lattice distortion caused by solid solution elements, optimizing the size and distribution of the second phase particles, so that the conductivity of the material reaches 63-67% IACS.

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