Aluminum alloy foil

Abstract

The present invention relates to a rolled aluminum alloy battery electrode foil, comprising 0.06 to 0.16 wt% Si, 0.41 to 1.0 wt% Fe, ≤0.25 wt% Cu, ≤0.10 wt% Mn, ≤0.03 wt% Mg, ≤0.05 wt% Zn, and 0.001 to 0.030 wt% Ti, each comprising ≤0.05 wt% of impurities totaling ≤0.15 wt%, with the remainder being Al, having a thickness of 10 to 25 μm, and having a tensile strength of at least 190 MPa and an elongation of at least 3% when measured after heat treatment of the aluminum foil at 120°C for 2 minutes. The present invention further relates to a battery electrode foil, an electrode for a secondary battery, and a method for producing a secondary battery.

Description

Technical Field

[0001] The present invention relates to an aluminum alloy battery electrode foil having high strength and elongation and high thermal stability. The present invention further relates to a battery electrode foil, an electrode for a secondary battery, and a method for producing a secondary battery.

Background Art

[0002] Secondary batteries using non-aqueous electrolytes such as lithium ion batteries are widely used in various applications such as electronic devices, power tools, electric vehicles, and grid storage. In a lithium ion battery, the positive electrode is usually made of a thin aluminum alloy foil coated with a positive electrode active material on both sides. The aluminum alloy foil functions as a current collector and is very thin, usually less than 25 μm thick. In other types of batteries, the current collector for the negative electrode may also be made of aluminum. The production of a positive electrode for a lithium ion battery includes coating an aluminum alloy foil with an active material, then drying at an elevated temperature, for example 100 to 180 ° C, and finally calendaring to compress the active material. The positive electrode is then laminated with the negative electrode, separator and electrolyte, wound or folded to form a battery cell, and finally the battery cell is filled into, for example, a cylindrical or prismatic casing or a pouch.

[0003] To avoid breakage of the aluminum alloy foil during battery production, the foil must have high strength and high elongation. However, both strength and elongation usually decrease when the foil is exposed to elevated temperatures during the drying process, which may cause problems of rupture during subsequent calendaring and winding, or folding.

[0004] US9847530B2 discloses an aluminum foil for an electrode current collector having a composition of 0.03 to 1.0% Fe, 0.01 to 0.2% Si, 0.0001 to 0.2% Cu, 0.005 to 0.03% Ti, the balance being Al and unavoidable impurities. The foil is produced by cold rolling to the final gauge without heat treatment after continuous casting. The aim is to obtain high strength, but the problem of elongation is not addressed.

[0005] US9947917B2 discloses aluminum foil for electrode current collectors, containing 1.0–2.0% Fe, 0.01–0.2% Si, 0.0001–0.2% Cu, and 0.005–0.3% Ti, with the remainder being Al and unavoidable impurities. The foil is produced by continuous casting followed by cold rolling to the final gauge without heat treatment. The objective is to obtain high strength, but the issue of elongation is not addressed.

[0006] US10916357B2 discloses an electrode current collector containing aluminum foil composed of 0.03-1.0% Fe, 0.01-0.2% Si, 0.0001-0.2% Cu, Al, and unavoidable impurities. The foil is produced by continuous casting, cold rolling to a cold reduction of 80% or less, heat treatment at 550-620°C for 1-15 hours, and then cold rolling to the final gauge. The objective is to obtain high strength and conductivity, but the problem of elongation is not addressed.

[0007] US10050257B2 discloses an electrode current collector formed by applying an active material to an aluminum alloy foil obtained by the final cold rolling of an aluminum alloy ingot containing 0.1 to 1.0 wt% Fe, 0.01 to 0.5 wt% Si, and 0.01 to 0.2 wt% Cu, with the remainder being Al and unavoidable impurities. This ingot is subjected to a homogenization treatment at 550°C to 620°C for 3 to 6 hours, followed by hot rolling at a starting temperature of 500°C to 550°C and an ending temperature of 255°C to 300°C, and then cold rolling. The objective is to obtain high strength and conductivity, but the problem of elongation is not addressed.

[0008] DE112013005772T5 discloses an aluminum alloy foil containing 0.1-0.6 wt% Si, 0.2-1.5 wt% Fe, with the remainder being aluminum and unavoidable impurities, where the sum of Si and Fe content is 0.48 wt% or more. The objective is to obtain high strength, but thermal stability is not addressed. Furthermore, the production of the foil requires hot rolling of the ingot at temperatures below 350°C, which is in practice extremely difficult to do without causing cracks in the material.

[0009] CN114277286A discloses an aluminum alloy foil for lithium batteries containing 0.01-0.25% Si, 0.08-0.4% Fe, 0.01-0.05% Cu, ≤0.02% Mn, ≤0.04% Zn, ≤0.04% Ti, and the remainder Al. The foil is produced by continuous casting, rolling to a thickness of 7 mm at a speed of 950 mm / min, and then cold rolling. Intermediate annealing for 27-35 hours is required to obtain sufficient mechanical properties.

[0010] WO2012008567A1 discloses an aluminum foil for battery current collectors containing 0.2–1.3 wt% Fe, 0.01–0.5 wt% Cu, and less than 0.2 wt% Si, with the remainder being Al and unavoidable impurities. The foil is produced by casting an ingot, followed by homogenization, hot rolling and cold rolling, and intermediate continuous annealing. The objective is to obtain a certain degree of strength, good elongation, and low electrical resistance, but the problem of thermal stability is not addressed.

[0011] US4000009A discloses a method for producing a wrought sheet of an aluminum alloy having a composition of 0.085% Si, 0.365% Fe, 0.034% Cu, 0.02% Ti, 0.0050% B, and the remainder being aluminum. The production method includes continuously casting a molten alloy to form a sheet, heating the continuously cast sheet to a temperature in the range of about 480–620°C, cooling at a rate of no more than 333°C per hour, and then cold-rolling and annealing. Foil for battery electrodes is not addressed.

[0012] CN104388766A discloses a method for producing aluminum foil for lithium-ion batteries, wherein the weight percentages of the components are Al≧99.35%, Si0.05~0.12%, Fe0.35~0.45%, Cu0.02~0.03%, Mn0.005%, Mg0.001%, Zn0.023%, Cr0.001%, and Ti0.015%, and the production method is controlled according to the control standards for pure aluminum ingots. The strips are produced in a horizontal continuous casting and rolling mill at a speed of 1050~1100 mm / min and rolled to 6~7 mm after 3 passes. The strips are then cold-rolled and subsequently subjected to intermediate heat treatment for complete recrystallization annealing (O tempering). The annealed strips are then cold-rolled and foil-rolled. Mechanical properties are not disclosed, and the issue of thermal stability is not addressed. Combining all mechanical requirements—satisfactory conductivity and the ability to produce without coil breakage or other problems during rolling—has been found difficult for battery electrode foils, particularly aluminum alloys. Therefore, an object of the present invention is to provide AA1xxx or AA8xxx aluminum alloy foils that combine high tensile strength, high elongation, and thermal stability. A further object of the present invention is to provide aluminum alloy foils that can be produced efficiently. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] US9847530B2 [Patent Document 2] US9947917B2 [Patent Document 3] US10916357B2 [Patent Document 4] US10050257B2 [Patent Document 5] DE112013005772T5 [Patent Document 6] CN114277286A [Patent Document 7] WO2012008567A1 [Patent Document 8] US4000009A [Patent Document 9] CN104388766A [Overview of the Initiative] [Means for solving the problem]

[0014] The present invention relates to a rolled aluminum alloy battery electrode foil (hereinafter referred to as aluminum alloy foil), comprising 0.06 to 0.16 wt% Si, 0.41 to 1.0 wt% Fe, ≤0.25 wt% Cu, ≤0.10 wt% Mn, ≤0.03 wt% Mg, ≤0.05 wt% Zn, and 0.001 to 0.030 wt% Ti, each comprising ≤0.05 wt% impurities totaling ≤0.15 wt%, with the remainder being Al. The as-rolled aluminum alloy foil has a thickness of 10 to 25 μm, preferably 10 to 16 μm. When the aluminum foil is heat-treated at 120°C for 2 minutes, the tensile strength is at least 190 MPa and the elongation is at least 3%.

[0015] The present invention further relates to a method for producing battery electrode foil, comprising the steps of: continuously casting, preferably twin-roll casting, an aluminum alloy having the above composition to obtain a sheet preferably with a thickness of 0.5 to 14 mm immediately after casting; cold rolling the cast sheet to an intermediate thickness, preferably 0.05 to 3 mm; annealing the sheet of intermediate thickness at a temperature of 150 to 320°C for 2 to 15 hours (also referred to as intermediate annealing); and cold rolling the annealed sheet to obtain a foil having a final thickness of 10 to 25 μm, wherein no heat treatment resulting in complete recrystallization is performed after continuous casting. Such heat treatment preferably does not exceed 320°C. [Modes for carrying out the invention]

[0016] Preferably, the tensile strength of the aluminum alloy foil, measured after heat treatment at 160°C for 2 minutes, is at least 100% of the tensile strength in the as-rolled state.

[0017] The as-rolled aluminum alloy foil preferably has a tensile strength of at least 190 MPa, most preferably at least 250 MPa, and particularly most preferably at least 290 MPa. Preferably, when measured after heat-treating the aluminum foil at 120°C for 2 minutes, the tensile strength is at least 100%, most preferably at least 110%, and particularly most preferably at least 120% of the as-rolled tensile strength. When measured after heat-treating the aluminum foil at 160°C for 2 minutes, the tensile strength is preferably at least 100%, most preferably at least 110% of the as-rolled tensile strength. Preferably, the tensile strength of the aluminum alloy foil when measured after heat-treating the as-rolled aluminum foil at 120°C or 160°C does not exceed 350 MPa.

[0018] The as-rolled aluminum alloy foil preferably has an elongation of at least 3%, most preferably at least 4%, and particularly most preferably at least 4.5%. Preferably, the elongation when measured after heat-treating the aluminum foil at 120°C for 2 minutes is at least 3.5%, most preferably at least 4%. When measured after heat-treating the aluminum foil at 160°C for 2 minutes, the elongation is preferably at least 2%, most preferably at least 2.5%, and particularly most preferably at least 3%. Preferably, the elongation of the as-rolled foil after heat-treatment at 120°C or 160°C does not exceed 15%.

[0019] The area-weighted average equivalent circle diameter of the grains projected onto a cross-section perpendicular to the rolling direction of the as-rolled aluminum foil is 2.4 μm or less, most preferably 2.3 μm or less. In many cases, the average equivalent circle diameter of the grains is at least 0.35 μm or at least 0.5 μm. The threshold value for determining grain boundaries is an azimuth difference of at least 10°.

[0020] The area-weighted average equivalent circle diameter of sub-grains projected onto a cross-section perpendicular to the rolling direction of the as-rolled aluminum foil is 0.9 μm or less, most preferably 0.8 μm or less. In many cases, the average equivalent circle diameter of the grains is at least 0.1 μm or at least 0.2 μm. The threshold for determining the sub-grain boundaries is an orientation difference of at least 2°.

[0021] The average circle diameter is preferably measured using EBSD (electron backscatter diffraction method) and commercially available software suitable for the purpose.

[0022] Fine grains and sub-grains have been found to improve the mechanical properties of aluminum foil.

[0023] The as-rolled aluminum foil preferably has a volume fraction of Cu texture {112}<111> of at least 20%, such as 20 - 50%, most preferably at least 22%, measured by EBSD. The texture is identified as having a deviation of up to 11° from the ideal orientation.

[0024] As used herein, the term "as-rolled" refers to the case where the aluminum alloy foil has been rolled to its final thickness but has not been further heat-treated, which is in most cases the state of the foil when the process for coating the foil with an electrode active material is initiated.

[0025] Unless otherwise specified, all parts and percentages refer to parts by weight and percentages by weight.

[0026] As used herein, the operator "≦" refers to the following and includes zero.

[0027] The texture and grain size, as well as mechanical properties such as tensile strength and elongation, may be measured as described in the examples of this specification.

[0028] The functions of various elements in the aluminum alloy are as follows: Si increases the strength of aluminum alloy foil, but too much Si leads to larger intermetallic particles, increasing the risk of pinholes. Too much Si also makes it difficult to achieve high elongation. The Si content in aluminum alloy is preferably 0.06 to 0.13 wt%.

[0029] Fe increases the strength of aluminum alloy foil, but too much Fe can coarse the intermetallic particles, leading to a risk of pinholes. The Fe content in the aluminum alloy is preferably 0.45 to 1.0 wt%, most preferably at least 0.460 wt%, or at least 0.50 wt%, for example 0.460 to 1.0 wt%, or 0.50 to 0.90 wt%, and most preferably 0.55 to 0.85 wt%.

[0030] While copper (Cu) increases the strength of aluminum alloy foil, too much Cu leads to increased work hardening during cold rolling, reducing elongation and increasing the risk of coil breakage. The Cu content in the aluminum alloy is preferably 0.05 to 0.20 wt%, most preferably 0.10 to 0.19 wt%.

[0031] While Zn does increase the strength of aluminum foil to some extent, too much Zn can lower the corrosion potential, making the foil more susceptible to corrosion and potentially affecting battery operation. The Zn content in the aluminum alloy is preferably 0.01 to 0.04 wt%, most preferably 0.02 to 0.04 wt%.

[0032] Ti is included as a grain refiner to reduce the risk of cracking. Too much Ti can coarse the intermetallic particles, leading to a risk of pinholes. The Ti content in aluminum alloys is preferably 0.005 to 0.025 wt%, most preferably 0.010 to 0.020 wt%.

[0033] A small amount of Mn increases the strength of aluminum alloy foil, but too much reduces its conductivity. The Mn content in the aluminum alloy is preferably 0.001 to 0.07 wt%, most preferably 0.01 to 0.05 wt%.

[0034] While magnesium (Mg) increases the hardness of aluminum alloy foil, it should not be included in excessive amounts, as this can lead to reduced elongation and the risk of coil breakage and other problems during rolling. The Mg content in the aluminum alloy is preferably ≤0.02 wt%, and most preferably ≤0.01 wt%.

[0035] Other elements may be present as impurities in amounts of ≤0.05 wt% each, totaling ≤0.15 wt%. Preferably, the impurity content in the aluminum alloy is ≤0.02 wt% each, totaling ≤0.15 wt%.

[0036] One aspect of the present invention relates to a foil of AA1xxx aluminum alloy containing 0.06 to 0.16 wt% Si, 0.41 to 0.85 wt% Fe, 0.05 to 0.20 wt% Cu, 0.001 to 0.05 wt% Mn, ≤0.03 wt% Mg, ≤0.05 wt% Zn, 0.005 to 0.030 wt% Ti, each ≤0.05 wt% of impurities totaling ≤0.15 wt%, with the remainder being Al.

[0037] Another aspect of the present invention relates to a foil of AA8xxx aluminum alloy containing 0.06 to 0.16 wt% Si, 0.70 to 1.0 wt% Fe, ≤0.02 wt% Cu, 0.001 to 0.05 wt% Mn, ≤0.01 wt% Mg, ≤0.03 wt% Zn, 0.001 to 0.030 wt% Ti, each ≤0.05 wt% of impurities totaling ≤0.15 wt%, with the remainder being Al.

[0038] As-rolled aluminum alloy foil preferably has an electrical conductivity of at least 50% IACS, most preferably at least 55% IACS.

[0039] As-rolled aluminum alloy foil is preferably tempered to H14, H16, H18, or H19, most preferably H18, and so on (H1x temper). This is achieved by not performing any heat treatment after cold rolling is completed to the final thickness.

[0040] Aluminum alloy foil is produced by a method which preferably includes continuous casting, most preferably twin-roll continuous casting into sheets. The thickness of the sheet immediately after casting is preferably 1 to 10 mm, most preferably 3 to 5.8 mm. The casting rate is preferably 1200 to 2000 mm / min, most preferably 1400 to 1700 mm / min. The low thickness and high casting rate result in a high cooling rate, which is advantageous in terms of maintaining a high Fe content in the solid solution. The method preferably further includes the steps described herein.

[0041] Compared to semi-continuous casting to ingots, continuous casting, particularly twin-roll casting, has a much higher cooling rate. The cooling rate from 690°C to 120°C is preferably 350-700°C / sec, most preferably 400-600°C / sec. This affects the microstructure by increasing the number of intermetallic particles with equivalent circle diameters in the range of, for example, 0.1-1 μm. Continuous casting with high cooling rates has also been found to promote an increase in the amount of Fe and Si in the solid solution, which enhances thermal stability.

[0042] Intermediate annealing is most preferably carried out to a thickness of 0.05 to 2 mm, and most preferably to 0.2 to 2.4 mm. Cold rolling before intermediate annealing is preferably carried out with a thickness reduction of 40 to 99%, most preferably to 50 to 96%. Cold rolling after intermediate annealing is preferably carried out with a thickness reduction of 75 to 99.8%, most preferably to 88 to 99.7%.

[0043] The intermediate annealing temperature is preferably 190-300°C, most preferably 200-290°C or 200-275°C. The intermediate annealing time is preferably 2-10 hours, most preferably 3-9 hours. It has been found that omitting intermediate annealing leads not only to coil breakage during rolling but also to low thermal stability, i.e., insufficient tensile strength or elongation after heat treatment at 120°C and 160°C.

[0044] In contrast to high-temperature annealing, intermediate annealing is performed within a temperature range that does not cause recrystallization of the aluminum alloy, but rather relieves stress.

[0045] To avoid recrystallization after continuous casting, aluminum alloys are preferably not subjected to heat treatment above 310°C, more preferably not above 300°C, most preferably not above 290°C, and most preferably not above 275°C. Heat treatment at excessively high temperatures has been found to result in a decrease in thermal stability with respect to tensile strength and elongation.

[0046] It has been found that avoiding recrystallization improves the thermal stability of aluminum foil. The large amount of Fe in the solid solution, accelerated by the high cooling rate after casting, allows for heat treatment at higher temperatures without recrystallization. High cold pressure before heat treatment lowers the temperature at which recrystallization occurs.

[0047] The aluminum alloy foil according to the present invention has been found to have a fine and uniform granular structure throughout the entire material, not only on the surface but also in the center of the foil. Consequently, it has been found that a combination of high tensile strength, high elongation, and thermal stability can be obtained.

[0048] The present invention also relates to an electrode for a secondary battery comprising an aluminum alloy foil current collector as described herein and a coating on both sides of the foil with an electrode active material. The coating may be, for example, 5 to 150 μm thick on each side. The electrode is preferably the positive electrode of a secondary battery such as a lithium-ion battery or a sodium-ion battery. The electrode active material, particularly the positive electrode material, may optionally include a variety of materials such as lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel manganese cobalt oxide (NMC), lithium nickel cobalt aluminum oxide (NCA), lithium iron phosphate (LFP), lithium titanate (LTO), and others known in the art, in combination with an intermediate carbon coating.

[0049] The present invention relates, lastly, to a secondary battery comprising a negative electrode, a positive electrode, a non-aqueous electrolyte, and a separator, particularly a lithium-ion battery or a sodium-ion battery, wherein at least one of the negative electrode or positive electrode is an electrode as described herein. The negative electrode, positive electrode, separator, and electrolyte are preferably laminated, folded, or wound into a package that is arranged in a rigid casing such as a prismatic or cylindrical casing, or a flexible casing such as a pouch-type packaging material. [Examples]

[0050] Aluminum alloy foil having the composition according to Table 1 was prepared by continuous twin-roll casting from a molten material at approximately 700°C at a speed of 1470-1600 mm / min to obtain a sheet with a thickness of approximately 5.6 mm directly from the casting rolls, and then cooling at a rate of approximately 450°C / sec to approximately 120°C. The sheet was cold-rolled and processed as shown in Table 2, where "H" means the temperature and time of homogenization (if any), "IA" means the temperature and time of intermediate annealing (if any), "IA gauge" means the thickness in mm when intermediate annealing (if any) was performed, "final gauge" means the final thickness in mm after cold rolling was completed, and "coil break" indicates whether there was one or more coil breaks during cold rolling. If homogenization was performed, this was done to a thickness of 2.4 mm after cold rolling, except for Test No. 6, where homogenization was performed to a thickness of 3.05 mm.

[0051] Samples from tests No. 6-12 and No. 14-25 were examined by EBSD (electron backscatter diffraction) to determine the microstructure and grain size, expressed as the equivalent circle diameter (ECD). Samples were prepared by fixing them with metal clamps and mechanically polishing them at room temperature. The SEM was operated at a magnification of 1000x, voltage of 10kV, and step size of 0.1μm. A deviation of 11° from the ideal orientation was applied to determine the microstructure component Cu{112}. <111> , S{123} <634> , and Brass{011} <211> The fractions were determined. A threshold of 10° orientation difference was applied to grain boundaries and a threshold of 2° orientation difference to subgrain boundaries to determine the area-weighted equivalent circle diameter (ECD) of grains and subgrains projected onto a cross section perpendicular to the rolling direction. The results are shown in Table 3.

[0052] Each foil sample was tested for as-rolled ("AR") tensile strength (UTS) and elongation after heat treatment at 120°C for 2 minutes and at 160°C for 2 minutes. Tensile and elongation tests were performed on longitudinally parallel samples with a width of 0.5'' (12.7 mm), using a preload of 0.5 mm / min crosshead speed up to 0.22 N and a test speed of 5 mm / min crosshead speed. The heat treatments at 120°C and 160°C were performed in an oil bath, mimicking the drying process in electrode formation, where the foil-wrapped samples were immersed for 2 minutes, removed, and rapidly cooled. Thickness was measured according to ASTM E 252, based on the weight of a circular sample cut with a precision die of a known area. The results are shown in Table 4.

[0053] [Table 1]

[0054] Other elements: ≤0.05 wt% each, ≤0.15 wt% total. Remainder: Aluminum.

[0055] [Table 2]

[0056] In tests 13 to 25 according to the present invention, intermediate annealing was performed in such a way that stress relief was achieved but recrystallization was not.

[0057] [Table 3]

[0058] [Table 4]

[0059] In tests 13 to 21 according to the present invention, the target tensile strength and elongation after heat treatment at 120°C were achieved, but in comparative tests 1 to 12, it appears that at least one of the tensile strength or elongation fell below the target.

Claims

1. A rolled aluminum alloy battery electrode foil comprising 0.06 to 0.16 wt% Si, 0.41 to 1.0 wt% Fe, ≤0.25 wt% Cu, ≤0.10 wt% Mn, ≤0.03 wt% Mg, ≤0.05 wt% Zn, and 0.001 to 0.030 wt% Ti, each in ≤0.05 wt% impurities totaling ≤0.15 wt%, with the remainder being Al, having a thickness of 10 to 25 μm, and having a tensile strength of at least 190 MPa and an elongation of at least 3% when measured after heat treatment of the aluminum foil at 120°C for 2 minutes.

2. The battery electrode foil according to claim 1, wherein, when measured after heat treatment of the aluminum foil at 120°C for 2 minutes, the tensile strength is at least 100%, preferably at least 120%, of the tensile strength in the as-rolled state.

3. The battery electrode foil according to claim 1, wherein the tensile strength, when measured after heat treatment of the aluminum foil at 160°C for 2 minutes, is at least 100% of the tensile strength in the as-rolled state.

4. The battery electrode foil according to claim 1, wherein the as-rolled foil has a tensile strength of at least 190 MPa, preferably at least 250 MPa, and most preferably at least 290 MPa.

5. The battery electrode foil according to claim 1, wherein the as-rolled foil has an elongation of at least 4%.

6. The battery electrode foil according to claim 1, wherein the aluminum alloy contains 0.45 to 1.0 wt% Fe, preferably 0.460 to 1.0 wt% Fe.

7. The battery electrode foil according to claim 1, wherein the aluminum alloy contains 0.05 to 0.20 wt% Cu, preferably 0.10 to 0.19 wt% Cu.

8. The battery electrode foil according to claim 1, wherein the area-weighted average equivalent circle diameter of grains projected onto a cross section perpendicular to the rolling direction of the aluminum foil, where the threshold of the grain boundary is an orientation difference of at least 10°, is 2.4 μm or less, preferably 2.3 μm or less.

9. The battery electrode foil according to claim 1, wherein the area-weighted average equivalent circle diameter of subgrains, projected onto a cross section perpendicular to the rolling direction of the aluminum foil, and having a subgrain boundary threshold of at least 2° orientation difference, is 0.9 μm or less, preferably 0.8 μm or less.

10. The battery electrode foil according to claim 1, wherein the volume fraction of Cu structure {112}<111>, measured by EBSD with a deviation of up to 11° from the ideal orientation, is at least 20%, preferably at least 22%.

11. The battery electrode foil according to claim 1, wherein the foil is produced by a method including continuous casting and cold rolling with intermediate annealing, and no heat treatment is performed after continuous casting to result in complete recrystallization.

12. A method for producing battery electrode foil, comprising the steps of: continuously casting an aluminum alloy containing 0.06 to 0.16 wt% Si, 0.41 to 1.0 wt% Fe, ≤0.25 wt% Cu, ≤0.10 wt% Mn, ≤0.03 wt% Mg, ≤0.05 wt% Zn, and 0.001 to 0.030 wt% Ti, each containing ≤0.05 wt% impurities, with the remainder being ≤0.15 wt%, to obtain a sheet; cold rolling the cast sheet to an intermediate thickness; annealing the sheet of intermediate thickness at a temperature of 150 to 320°C for 2 to 15 hours; and cold rolling the annealed sheet to obtain a foil having a final thickness of 10 to 25 μm, wherein no heat treatment resulting in complete recrystallization is performed after continuous casting.

13. The method according to claim 12, wherein cold rolling after intermediate annealing is performed with a thickness reduction rate of 75 to 99.8%.

14. An electrode for a secondary battery, comprising a current collector of a battery electrode foil according to any one of claims 1 to 11.

15. A secondary battery comprising a negative electrode, a positive electrode, a non-aqueous electrolyte, and a separator, wherein at least one of the negative electrode or the positive electrode is the electrode described in claim 14.