Alloy formula and preparation process of low-impurity high-conductivity electrode aluminum foil

Abstract

The application belongs to the technical field of alloy formula, and particularly relates to an alloy formula and a preparation process of a low-impurity high-conductivity electrode aluminum foil. The alloy formula takes high-purity aluminum as a matrix and contains, in percentage by weight, Cu 0.012-0.04%, Mg 0-0.02%, Ti 0.01-0.02%, B 0.002-0.006%, and at least one of Zr 0-0.008%, Nb 0-0.002%, Cr 0-0.005%, Zn 0-0.005%, Mn 0-0.006%, V 0-0.002%, Ce 0-0.003%, La 0-0.002%, Hf 0-0.002%, Sn 0-0.005%, Sb 0-0.001%, and Ta 0-0.001% which can be selectively added; and the total content of impurities is less than or equal to 0.05 wt%, wherein Fe is less than or equal to 0.025 wt%, Si is less than or equal to 0.018 wt%, and the rest of the impurities is less than or equal to 0.005 wt%.

Description

Technical Field

[0001] This invention belongs to the field of alloy formulation technology, and particularly relates to the alloy formulation and preparation process of low-impurity, high-conductivity electrode aluminum foil. Background Technology

[0002] The rapid development of the new energy industry places stringent demands on the performance of electrode aluminum foil in core equipment such as power batteries, supercapacitors, and photovoltaic inverters. On the one hand, it needs high conductivity to reduce energy transmission loss and ensure charging and discharging efficiency and power output stability. On the other hand, it needs sufficient mechanical strength to prevent deformation or breakage during rolling, cutting, and assembly. Simultaneously, it must strictly control impurity content to prevent the formation of intermetallic compounds such as AlFeSi from Fe, Si, and Mn. These compounds not only significantly reduce the conductivity of the aluminum foil but may also cause localized corrosion in the electrochemical environment, shortening the equipment's lifespan. However, while pure aluminum electrode foil has high conductivity (typically around 60% IACS), its tensile strength is generally below 100 MPa, making it difficult to meet the structural stability requirements under complex operating conditions. Conventional alloyed aluminum foil, although its strength is improved by adding elements such as Cu and Mg, often suffers from conductivity dropping below 60% IACS due to improper element ratio control or insufficient impurity control precision, with total impurity content often exceeding 0.08 wt%, failing to achieve a synergistic optimization of low impurities, high conductivity, and mechanical properties.

[0003] At the manufacturing process level, the production of existing electrode aluminum foil still faces several bottlenecks: the smelting stage often employs single-solvent refining or simple vacuum degassing, which has limited efficiency in removing trace impurities and gases, easily leading to residual inclusions and pores inside the ingot, resulting in cracks or pinhole defects during subsequent rolling; the matching between crystallization and rolling processes is insufficient. For example, improper control of the cooling rate during semi-continuous casting can easily lead to coarse grains, while unreasonable intermediate annealing parameters after multi-pass cold rolling can result in incomplete elimination of work hardening or excessive grain growth, further exacerbating the performance contradiction between conductivity and mechanical strength. In addition, the development of specialized technologies for specific application scenarios is lagging behind. For example, low-temperature energy storage systems in northern regions require aluminum foil to maintain stable mechanical properties at -40℃, excellent corrosion resistance is required in marine climates, and low impedance loss is required for high-frequency radio frequency power supplies. However, existing general-purpose aluminum foil often cannot simultaneously meet these scenario-specific requirements, necessitating multiple process adjustments or additional coating treatments, which not only increases production costs but may also affect core performance due to process compatibility issues, thus hindering the development of new energy equipment towards high reliability and scenario-specific applications. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned technical problems by providing an alloy formulation and preparation process for low-impurity, high-conductivity electrode aluminum foil.

[0005] In view of this, the present invention provides an alloy formulation for low-impurity, high-conductivity electrode aluminum foil, wherein the alloy formulation uses high-purity aluminum as a base and comprises, by weight percentage: Cu 0.012-0.04%, Mg 0-0.02%, Ti 0.01-0.02%, B 0.002-0.006%, and optionally at least one of Zr 0-0.008%, Nb 0-0.002%, Cr 0-0.005%, Zn 0-0.005%, Mn 0-0.006%, V 0-0.002%, Ce 0-0.003%, La 0-0.002%, Hf 0-0.002%, Sn 0-0.005%, Sb 0-0.001%, Ta 0-0.001%; The total impurity content is ≤0.05wt%, of which Fe≤0.025wt%, Si≤0.018wt%, and other impurities≤0.005wt%.

[0006] Preparation process of low-impurity high-conductivity alloy formulation, step one: vacuum dry high-purity aluminum ingots and intermediate alloy / pure metal particles containing formulation elements at 120-150℃ for 4-7h; Step 2: Add the pretreated raw materials to a vacuum induction furnace, heat to 720-750℃ to melt, add alloying elements and stir at 250-400r / min for 15-30min, introduce protective gas, and purify by solvent refining or vacuum refining combined with vacuum degassing. Step 3: Control the crystallizer water temperature to 18-30℃ and the casting speed to 60-90mm / min to obtain ingots through semi-continuous casting; Step 4: Homogenize and anneal the ingot at 530-560℃ for 6-11 hours, then cool. Step 5: First, hot roll to 5-15mm, then cold roll to 0.05-0.15mm in multiple passes. The reduction rate of each cold rolling pass is 5%-35%. Intermediate annealing is performed at 320-360℃ for 1.5-3h every two passes. Step Six: Anneal the cold-rolled aluminum foil at 270-320℃ and then cool it. Step 7: Perform surface treatment on the finished annealed aluminum foil; the aluminum foil has a conductivity ≥62% IACS, a tensile strength of 105-180MPa, and a total impurity content ≤0.05wt%.

[0007] Preferably, the purity of the high-purity aluminum ingot is 99.99% or higher; In step two, the protective gas is argon, helium, or a mixture of argon and nitrogen. The argon flow rate is 1.2-2.5 L / min, the helium flow rate is 1.2 L / min, and the volume ratio of the argon to nitrogen mixture is 1:1 with a flow rate of 1.8 L / min.

[0008] Preferably, in step two, the solvent refining uses at least one of Na3AlF6, KAlF4, and LiF, with a solvent addition amount of 1%-2.5%; the vacuum refining is performed at a vacuum degree of 0.001-0.005 MPa, a temperature of 710-740℃, and a time of 20-40 min; the vacuum degassing is performed at a vacuum degree of 0.001-0.005 MPa and a temperature of 710-740℃.

[0009] Preferably, in step three, the ingot size of the semi-continuous casting can be selected as a round ingot with a diameter of Φ100-220mm or a wide ingot with a diameter of 1200mm×200mm×6000mm; the ingot can be selectively subjected to liquid nitrogen mist cooling at a cooling rate of 10℃ / s, or vacuum aging treatment at 200℃ for 5h.

[0010] Preferably, the cooling method for homogenization annealing in step four is air cooling, furnace cooling, or slow cooling, with a slow cooling rate of 5°C / min.

[0011] Preferably, in step five, cold rolling can be selectively performed using tension rolling with a tension of 50 N / mm. 2 Alternatively, asynchronous rolling can be used, with an upper and lower roll speed ratio of 1.05; after cold rolling, the aluminum foil can be straightened.

[0012] Preferably, the annealing time of the finished product in step six is ​​0.5-2 hours, the cooling method is air cooling or furnace cooling, and the incomplete annealing conditions are 320℃ for 40 minutes.

[0013] Preferably, the surface treatment in step seven includes at least one of electrochemical polishing, ultrasonic cleaning, passivation, anodizing and sealing, precision polishing, and stress relief treatment; wherein: Electrochemical polishing was performed using a phosphoric acid-sulfuric acid system with a current density of 2 A / dm³. 2 Time: 30 seconds; Anodizing was performed using a sulfuric acid system, resulting in an oxide film thickness of 8 μm. Sealing was achieved by immersion in a silane coupling agent for 5 minutes. After precision polishing, the surface roughness Ra is ≤ 0.1 μm; The stress relief treatment conditions were 150℃ for 30 minutes.

[0014] The beneficial effects of this invention are: Through precise micro-alloying design and multi-stage purification processes, the technical challenge of achieving low impurities, high conductivity, and mechanical properties simultaneously in traditional electrode aluminum foil has been effectively overcome. Using high-purity aluminum as the matrix, the synergistic effect of conductivity-promoting elements and grain-refining elements is scientifically controlled. This avoids the weakening of conductivity due to the formation of intermetallic compounds from harmful impurities. Furthermore, through the dual action of solute atom clusters and heterogeneous nucleation cores, high conductivity is ensured while significantly improving mechanical strength. This allows the aluminum foil to possess excellent energy transmission efficiency while withstanding external forces during rolling, assembly, and operation, reducing the risk of deformation and breakage. Simultaneously, it lowers the risk of localized corrosion in electrochemical environments, extending the service life of downstream equipment.

[0015] At the manufacturing process level, this invention effectively solves bottleneck problems in traditional processes, such as incomplete impurity removal, uneven ingot structure, and numerous processing defects, by optimizing parameters in each stage of melting, casting, rolling, and annealing. The multi-stage purification process can deeply remove inclusions and gases from the melt. Combined with gradient cooling and precise annealing control, it can optimize the grain structure of aluminum foil, reduce defects such as pinholes and cracks, and improve product consistency and stability. Simultaneously, differentiated technical solutions designed for different application scenarios can meet the special requirements of low-temperature environments, marine climates, high-frequency operating conditions, and wide-width equipment without additional complex processing. This not only simplifies the production process and reduces overall costs but also provides key material support for the development of new energy equipment towards high reliability and scenario-based applications, broadening the application range of electrode aluminum foil. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the preparation process of the alloy formulation for the low-impurity, high-conductivity electrode aluminum foil of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0018] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "lateral," "longitudinal," and "center," are only used to explain the relative positional relationships and connections between components in a specific state (as shown in the accompanying drawings). They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0019] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0021] This solution addresses the core requirements of aluminum foil electrodes for low impurities, high conductivity, and stable mechanical properties. Using high-purity aluminum as the matrix, it employs precise microalloying design to control the crystal structure and precipitated phase morphology. Combined with a three-stage preparation process of purification, refinement, and densification, it develops eight differentiated technical solutions suitable for various scenarios such as power batteries, supercapacitors, and photovoltaic inverters. The core innovation lies in the use of selective impurity adsorption and synergistic microalloying refinement technology. While ensuring a conductivity ≥62% IACS, it increases the tensile strength of the aluminum foil to 120-180 MPa, and controls the total impurity content to below 0.05 wt%.

[0022] Based on 1070 high-purity aluminum, trace amounts of conductivity-promoting elements (Cu, Mg) and grain-refining elements (Ti, B, Zr) are introduced. The element ratio is optimized through first-principles calculations, so that Cu and Mg form solute atom clusters to hinder dislocation movement and improve strength, while the Ti-B-Zr composite phase acts as a heterogeneous nucleation core to refine the grains. The content of harmful impurities such as Fe, Si, and Mn is strictly controlled to avoid the formation of AlFeSi intermetallic compounds that reduce conductivity.

[0023] Impurity volatilization and oxidation control are achieved through vacuum induction melting and inert gas protection. Inclusions and gases are removed through two-stage purification using solvent refining and vacuum degassing. Semi-continuous casting combined with gradient cooling controls the uniformity of ingot structure. Multi-pass cold rolling combined with intermediate annealing eliminates work hardening. Finally, a balance between electrical conductivity and mechanical properties is achieved through low-temperature finished product annealing.

[0024] Example 1: Universal low-impurity, high-conductivity electrode aluminum foil, suitable for conventional energy storage batteries; Alloy formulation (wt%): Al 99.94, Cu 0.03, Mg 0.01, Ti 0.015, B 0.003, Zr 0.002, impurities (Fe ≤ 0.02, Si ≤ 0.015, others ≤ 0.005).

[0025] 99.99% high-purity aluminum ingots were selected. Cu and Mg were added in the form of Al-Cu and Al-Mg master alloys, and Ti, B, and Zr were added as Al-Ti-B-Zr composite refining agents. All raw materials were vacuum dried at 120℃ for 4 hours to remove moisture.

[0026] The temperature in the vacuum induction furnace is raised to 740℃. After high-purity aluminum ingots are added and melted, intermediate alloys and refining agents are added sequentially. The stirring speed is maintained at 300 r / min for 15 min, and argon gas (flow rate 1.5 L / min) is introduced for protection. Solvent refining (Na3AlF6 content 2%) is used. After standing for 20 min, vacuum degassing is performed (vacuum degree 0.005 MPa, temperature 730℃). Semi-continuous casting is performed with crystallizer water temperature 25℃ and casting speed 80 mm / min to obtain Φ200 mm ingots.

[0027] Homogenization annealing (550℃, 8h), air cooling; hot rolling to 10mm (initial rolling temperature 500℃, final rolling temperature 350℃); cold rolling to 0.1mm, with pass reduction rates of 30%, 25%, 20%, 15%, and 10% respectively, and intermediate annealing (350℃, 2h) every two passes.

[0028] Finished product annealing (300℃, 1h), air cooling; surface electrochemical polishing (phosphoric acid-sulfuric acid system, current density 2A / dm³). 2 (Time: 30 seconds)

[0029] Conductivity 63.5% IACS, tensile strength 125MPa, elongation 8%, total impurity content 0.038wt%, surface roughness Ra≤0.2μm.

[0030] Example 2: Ultra-high conductivity electrode aluminum foil adapted to supercapacitor; Alloy formulation (wt%): Al 99.96, Cu 0.015, Ti 0.01, B 0.002, Zr 0.001, Nb 0.002, impurities (Fe ≤ 0.015, Si ≤ 0.01, others ≤ 0.003).

[0031] 99.995% ultra-high purity aluminum ingots were selected, and Nb was added as an Al-Nb master alloy (Nb content 5%). Other elements were the same as in Example 1. The drying temperature was 150℃ and the time was 6h.

[0032] The vacuum induction furnace is heated to 720℃, and after melting, an intermediate alloy is added. The stirring speed is 250r / min and maintained for 20min, with an argon flow rate of 2L / min. Vacuum refining (vacuum degree 0.001MPa, temperature 710℃, time 30min) is used instead of solvent refining. Semi-continuous casting is carried out with a crystallizer water temperature of 20℃, a casting speed of 70mm / min, and an ingot diameter of 180mm.

[0033] Homogenization annealing (530℃, 10h), furnace cooling to 300℃ followed by air cooling; hot rolling to 8mm (initial rolling 480℃, final rolling 320℃); cold rolling to 0.08mm, with pass reduction controlled at 25%-10%, intermediate annealing temperature 330℃, time 2.5h.

[0034] Low-temperature annealing of finished products (280℃, 1.5h), followed by furnace cooling; surface cleaning (ultrasonic cleaning with deionized water and ethanol).

[0035] Conductivity 65.2% IACS, tensile strength 110MPa, elongation 10%, total impurity content 0.028wt%, volume resistivity ≤2.7μΩ·cm.

[0036] Example 3: High-strength, high-conductivity electrode aluminum foil adapted for power battery tabs; Alloy formulation (wt%): Al 99.91, Cu 0.04, Mg 0.02, Ti 0.018, B 0.004, Cr 0.005, Zn 0.003, impurities (Fe ≤ 0.025, Si ≤ 0.018, others ≤ 0.005).

[0037] The high-purity aluminum ingot is 99.99%, Cr is added as an Al-Cr master alloy (Cr content 10%), Zn is pure zinc granules, and the drying temperature is 130℃ for 5 hours.

[0038] Melt at 750℃, add intermediate alloy and stir at 400 r / min for 20 min, then introduce helium (flow rate 1.2 L / min); solvent refining (KAlF 41.5% and Na3AlF 61%), let stand for 30 min and then degas under vacuum (0.003 MPa, 740℃); semi-continuous casting, crystallizer water temperature 30℃, casting speed 90 mm / min, ingot Φ220 mm.

[0039] Homogenization annealing (560℃, 6h), air cooling; hot rolling to 12mm (initial rolling 520℃, final rolling 380℃); cold rolling to 0.12mm, maximum reduction per pass 35%, intermediate annealing temperature 360℃, time 1.5h, final reduction 12%.

[0040] Incomplete annealing (320℃, 40 min), air cooling; surface passivation treatment (immersion in chromate solution for 10 s).

[0041] 3. Performance indicators: conductivity 62.0% IACS, tensile strength 175MPa, elongation 5%, total impurity content 0.048wt%, and resistance to bending ≥100 times (180° bending).

[0042] Example 4: Low-temperature environment-adapted electrode aluminum foil for northern energy storage systems; Alloy formulation (wt%): Al 99.93, Cu 0.025, Mg 0.012, Ti 0.02, B 0.005, Mn 0.006, V 0.002, impurities (Fe ≤ 0.02, Si ≤ 0.015, others ≤ 0.005).

[0043] High-purity aluminum ingots (99.99%), with Mn and V added as an Al-Mn-V composite master alloy, dried at 140℃ for 6 hours.

[0044] Melt at 730℃, add intermediate alloy and stir at 350 r / min for 25 min, under argon and nitrogen mixed protection (volume ratio 1:1, flow rate 1.8 L / min); solvent refining (Na3AlF6 2.5%), stand for 25 min and then degas under vacuum (0.004 MPa, 720℃); semi-continuous casting, crystallizer water temperature 28℃, casting speed 75 mm / min, ingot Φ200 mm, immediately after casting and then liquid nitrogen mist cooling (cooling rate 10℃ / s).

[0045] Homogenize and anneal (540℃, 9h), slow cool (5℃ / min) to 200℃ and air cool; hot roll to 10mm (initial rolling 490℃, final rolling 340℃); cold roll to 0.1mm, pass reduction 25%-10%, intermediate annealing temperature 340℃, time 2h, followed by one pass of medium-temperature rolling (200℃, reduction 15%).

[0046] The finished product is annealed (300℃, 2h) and then cooled in the furnace to 100℃ and air-cooled. The surface is coated with a low-temperature antifreeze coating (organic silicone resin, 5μm thick).

[0047] Conductivity 63.0% IACS, tensile strength 140MPa at -40℃, tensile strength 135MPa at room temperature, elongation 7%, total impurity content 0.042wt%, no cracks when bent at low temperature.

[0048] Example 5: High corrosion-resistant and high conductivity electrode aluminum foil adapted for marine climate energy storage equipment; Alloy formulation (wt%): Al 99.92, Cu 0.02, Mg 0.01, Ti 0.016, B 0.004, Zn 0.005, Ce 0.003, La 0.002, impurities (Fe ≤ 0.02, Si ≤ 0.015, others ≤ 0.005).

[0049] High-purity aluminum ingots (99.99%), Ce and La added as Al-RE master alloy (total RE content 8%), dried at 130℃ for 5 hours.

[0050] Melt at 740℃, add intermediate alloy and stir at 300 r / min for 30 min, then introduce high-purity argon gas (flow rate 2.2 L / min); solvent refining (Na3AlF6 1.8% and LiF 0.5%), let stand for 30 min and then degas under vacuum (0.002 MPa, 730℃); semi-continuous casting, crystallizer water temperature 25℃, casting speed 85 mm / min, ingot Φ210 mm.

[0051] Homogenization annealing (550℃, 7h), air cooling; hot rolling to 11mm (initial rolling 510℃, final rolling 360℃); cold rolling to 0.11mm, pass reduction rate 30%-12%, intermediate annealing temperature 350℃, time 2h.

[0052] The finished product was annealed (310℃, 1.5h) and air-cooled; the surface was anodized (sulfuric acid system, oxide film thickness 8μm) and sealed (immersion in silane coupling agent for 5min).

[0053] Conductivity 62.5% IACS, tensile strength 130MPa, elongation 6%, no corrosion in neutral salt spray test (NSS) ≥500h, total impurity content 0.045wt%.

[0054] Example 6: Ultra-thin high-conductivity electrode aluminum foil adapted for microelectronic devices; Alloy formulation (wt%): Al 99.95, Cu 0.012, Ti 0.015, B 0.003, Zr 0.008, Hf 0.002, impurities (Fe ≤ 0.015, Si ≤ 0.01, others ≤ 0.003).

[0055] High-purity aluminum ingots (99.995%) were used, with Hf added as an Al-Hf master alloy (Hf content 3%). The drying temperature was 150℃ and the drying time was 7 hours.

[0056] Melt at 720℃, add intermediate alloy and stir at 250 r / min for 25 min, argon flow rate 2.5 L / min; vacuum refining (0.001 MPa, 710℃, 40 min); semi-continuous casting, using a small crystallizer (Φ100 mm), water temperature 18℃, casting speed 60 mm / min, vacuum aging after casting (200℃, 5 h).

[0057] Homogenization annealing (530℃, 11h), furnace cooling; hot rolling to 5mm (initial rolling 470℃, final rolling 300℃); cold rolling to 0.05mm, with the reduction rate gradually decreasing per pass (30%→25%→20%→15%→10%→5%), followed by low-temperature intermediate annealing (320℃, 3h) after each pass, and tension rolling (tension 50N / mm). 2 To avoid wrinkles.

[0058] The finished product is annealed at low temperature (270℃, 2h) and cooled in the furnace; the surface is then precision polished (Ra≤0.1μm).

[0059] 3. Performance indicators: conductivity 64.8% IACS, tensile strength 105MPa, elongation 9%, thickness tolerance ±0.002mm, total impurity content 0.028wt%, no pinhole defects.

[0060] Example 7: High-frequency scene-adaptive electrode aluminum foil adapted to RF power supply; Alloy formulation (wt%): Al 99.93, Cu 0.02, Mg 0.008, Ti 0.012, B 0.004, Sn 0.005, Sb 0.001, impurities (Fe ≤ 0.02, Si ≤ 0.015, others ≤ 0.005).

[0061] High-purity aluminum ingots (99.99%), with Sn and Sb added as pure metal particles, dried at 120℃ for 4 hours.

[0062] Melt at 735℃, add metal particles and stir at 350 r / min for 18 min with argon flow rate of 1.6 L / min; solvent refining (Na3AlF6 2.2%), stand for 22 min and then degas under vacuum (0.003 MPa, 725℃); semi-continuous casting, crystallizer water temperature 26℃, casting speed 80 mm / min, ingot Φ200 mm, control ingot grain size ≤50 μm.

[0063] Homogenization annealing (545℃, 8h), air cooling; hot rolling to 9mm (initial rolling 500℃, final rolling 350℃); cold rolling to 0.09mm, pass reduction rate 28%-10%, intermediate annealing temperature 345℃, time 1.8h, the last pass adopts asynchronous rolling (upper and lower roll speed ratio 1.05).

[0064] The finished product was annealed (290℃, 1.2h) and air-cooled; surface stress relief treatment was performed (150℃, 30min); high-frequency impedance testing and calibration were conducted.

[0065] Conductivity 63.2% IACS, tensile strength 120MPa, elongation 7.5%, impedance ≤0.05Ω at 100MHz, total impurity content 0.040wt%, high frequency loss ≤0.5%.

[0066] Example 8: Wide-width, high-uniformity electrode aluminum foil adapted for large photovoltaic inverters; Alloy formulation (wt%): Al 99.92, Cu 0.03, Mg 0.015, Ti 0.018, B 0.006, Zr 0.003, Ta 0.001, Nb 0.002, impurities (Fe ≤ 0.025, Si ≤ 0.018, others ≤ 0.005).

[0067] High-purity aluminum ingots (99.99%), with Ta and Nb added as an Al-Ta-Nb master alloy, dried at 140℃ for 6 hours.

[0068] Melt at 750℃, add intermediate alloy and stir at 400r / min for 25min with argon flow rate of 2.0L / min; solvent refining (KAlF 42% and Na3AlF 61%), stand for 30min and then degas under vacuum (0.004MPa, 740℃); use wide-width semi-continuous casting (ingot size 1200mm×200mm×6000mm), crystallizer water temperature 30℃, casting speed 65mm / min, and homogenize by water spray cooling after casting.

[0069] Homogenization annealing (560℃, 9h), air cooling; hot rolling to 15mm (initial rolling 530℃, final rolling 390℃), multi-roll rolling is used to ensure width uniformity; cold rolling to 0.15mm, pass reduction rate 32%-15%, intermediate annealing temperature 360℃, time 2.5h, and shape correction is performed after each pass.

[0070] The finished product is annealed (320℃, 1h) and air-cooled; after surface cleaning, a wide-width flatness test is performed (flatness ≤0.5mm / m).

[0071] Conductivity 62.2% IACS, tensile strength 145MPa, elongation 6.5%, width 1000mm (customizable), longitudinal conductivity deviation ≤0.3% IACS, total impurity content 0.046wt%.

[0072] Spectroscopic analysis is used to detect the composition of high-purity aluminum ingots and master alloys to ensure that the content of impurity elements meets the formula requirements; the melting temperature and vacuum degree are monitored in real time, and the liquid phase composition of the melt is tested regularly to ensure uniform distribution of elements; a laser thickness gauge is used to monitor the thickness of aluminum foil in real time, and the pass reduction rate deviation is controlled to ≤2% to ensure thickness uniformity; an eddy current conductivity meter is used to test conductivity (test point interval ≤50mm), a universal testing machine is used to test mechanical properties, and a metallographic microscope is used to observe grain structure to ensure that product performance meets standards.

[0073] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. An alloy formulation for low-impurity, high-conductivity electrode aluminum foil, characterized in that: The alloy formulation uses high-purity aluminum as a base and contains, by weight percentage: Cu 0.012-0.04%, Mg 0-0.02%, Ti 0.01-0.02%, B 0.002-0.006%, and optionally at least one of Zr 0-0.008%, Nb 0-0.002%, Cr 0-0.005%, Zn 0-0.005%, Mn 0-0.006%, V 0-0.002%, Ce 0-0.003%, La 0-0.002%, Hf 0-0.002%, Sn 0-0.005%, Sb 0-0.001%, Ta 0-0.001%; The total impurity content is ≤0.05wt%, of which Fe≤0.025wt%, Si≤0.018wt%, and other impurities≤0.005wt%.

2. A preparation process for a low-impurity, high-conductivity alloy formulation, based on the alloy formulation of the low-impurity, high-conductivity electrode aluminum foil according to claim 1, characterized in that: Step 1: Vacuum dry the high-purity aluminum ingots and intermediate alloy / pure metal granules containing the formula elements at 120-150℃ for 4-7 hours; Step 2: Add the pretreated raw materials to a vacuum induction furnace, heat to 720-750℃ to melt, add alloying elements and stir at 250-400r / min for 15-30min, introduce protective gas, and purify by solvent refining or vacuum refining combined with vacuum degassing. Step 3: Control the crystallizer water temperature to 18-30℃ and the casting speed to 60-90mm / min to obtain ingots through semi-continuous casting; Step 4: Homogenize and anneal the ingot at 530-560℃ for 6-11 hours, then cool. Step 5: First, hot roll to 5-15mm, then cold roll to 0.05-0.15mm in multiple passes. The reduction rate of each cold rolling pass is 5%-35%. Intermediate annealing is performed at 320-360℃ for 1.5-3h every two passes. Step Six: Anneal the cold-rolled aluminum foil at 270-320℃ and then cool it. Step 7: Perform surface treatment on the finished annealed aluminum foil; the aluminum foil has a conductivity ≥62% IACS, a tensile strength of 105-180MPa, and a total impurity content ≤0.05wt%.

3. The preparation process of the alloy formula for low-impurity, high-conductivity electrode aluminum foil according to claim 2, characterized in that: The purity of the high-purity aluminum ingot is 99.99% or higher; In step two, the protective gas is argon, helium, or a mixture of argon and nitrogen. The argon flow rate is 1.2-2.5 L / min, the helium flow rate is 1.2 L / min, and the volume ratio of the argon to nitrogen mixture is 1:1 with a flow rate of 1.8 L / min.

4. The preparation process of the alloy formula for low-impurity, high-conductivity electrode aluminum foil according to claim 2, characterized in that: In step two, solvent refining uses at least one of Na3AlF6, KAlF4, and LiF, with a solvent addition amount of 1%-2.5%; vacuum refining is performed at a vacuum degree of 0.001-0.005 MPa, a temperature of 710-740℃, and a time of 20-40 min; vacuum degassing is performed at a vacuum degree of 0.001-0.005 MPa and a temperature of 710-740℃.

5. The preparation process of the alloy formula for low-impurity, high-conductivity electrode aluminum foil according to claim 2, characterized in that: In step three, the ingot size for semi-continuous casting can be selected as a round ingot with a diameter of Φ100-220mm or a wide ingot with a diameter of 1200mm×200mm×6000mm; the ingot can be selectively cooled by liquid nitrogen mist at a cooling rate of 10℃ / s, or subjected to vacuum aging treatment at 200℃ for 5 hours.

6. The preparation process of the alloy formula for low-impurity, high-conductivity electrode aluminum foil according to claim 2, characterized in that: In step four, the cooling method for homogenization annealing is air cooling, furnace cooling, or slow cooling, with a slow cooling rate of 5℃ / min.

7. The preparation process of the alloy formula for low-impurity, high-conductivity electrode aluminum foil according to claim 2, characterized in that: In step five, cold rolling can optionally employ tension rolling with a tension of 50 N / mm. 2 Alternatively, asynchronous rolling can be used, with an upper and lower roll speed ratio of 1.05; after cold rolling, the aluminum foil can be straightened.

8. The preparation process of the alloy formula for low-impurity, high-conductivity electrode aluminum foil according to claim 2, characterized in that: In step six, the annealing time for the finished product is 0.5-2 hours, and the cooling methods are air cooling and furnace cooling. The incomplete annealing conditions are 320℃ for 40 minutes.

9. The preparation process of the alloy formula for low-impurity, high-conductivity electrode aluminum foil according to claim 2, characterized in that: The surface treatment in step seven includes at least one of the following: electrochemical polishing, ultrasonic cleaning, passivation, anodizing and sealing, precision polishing, and stress relief treatment; wherein: Electrochemical polishing was performed using a phosphoric acid-sulfuric acid system with a current density of 2 A / dm³. 2 Time: 30 seconds; Anodizing was performed using a sulfuric acid system, resulting in an oxide film thickness of 8 μm. Sealing was achieved by immersion in a silane coupling agent for 5 minutes. After precision polishing, the surface roughness Ra is ≤ 0.1 μm; The stress relief treatment conditions were 150℃ for 30 minutes.

Images