1XXX aluminum alloy blank for high-strength power battery foil as well as preparation method and application of 1XXX aluminum alloy blank

Abstract

The invention relates to a 1XXX aluminum alloy blank for a high-strength power battery foil as well as a preparation method and application of the 1XXX aluminum alloy blank, the 1XXX aluminum alloy blank comprises the following components in percentage by mass: one or two of 0.05-0.08% of Si, 0.26-0.29% of Fe, 0.04-0.07% of V, 0.015-0.025% of Ti, 0.01-0.05% of Mn or 0.01-0.05% of Cr, and the balance of Al and other inevitable impurities, and the atomic ratio of Fe / (Si + V) is controlled to be 1.1-2.0; v + Ti + Mn + Cr < = 0.13%; an alloy cast ingot is continuously prepared by adopting a semi-casting method, and then a hard aluminum foil blank is prepared through homogenizing annealing, hot rolling and cold rolling in sequence. The tensile strength of the aluminum alloy blank is 180-220 MPa, and the ductility is larger than or equal to 4%. The tensile strength of the battery foil prepared from the aluminum alloy blank is larger than or equal to 290 MPa, the ductility is larger than or equal to 3%, the resistivity is smaller than or equal to 3.1 mu omega.cm, the aluminum alloy blank can be used for a power battery current collector, the requirement for strength improvement of further thinning of the aluminum foil of the power battery current collector can be met, and the risk of coating strip breakage is reduced.

Description

Technical Field

[0001] The present invention relates to the field of aluminum alloy preparation, and in particular to a 1XXX aluminum alloy blank for high-strength power battery foil, a preparation method and application thereof. Background Art

[0002] The rapid development of the new energy vehicle industry has led to a rapid growth in the scale of lithium-ion power batteries in recent years, which has driven the demand for aluminum foil for battery current collectors. Driven by the continuous increase in battery specific energy density, the thickness of battery foil has continued to decrease. With the technical requirements of faster and faster coating speeds and wider coating widths, in order to prevent the aluminum foil from breaking during coating, the foil needs to have higher strength to reduce the risk of breaking caused by thinning.

[0003] Chinese patent CN201810698743.9 discloses "a kind of aluminum alloy foil for high-strength current collector and its manufacturing method". The aluminum foil contains Fe: 0.3-0.4wt%, Cu: 0.06-0.15wt%, La: 0.1-0.15wt%. The basic process flow is: add Al-20% La master alloy during smelting, cast aluminum block, hot-roll after 590-600℃×8h soaking (at 460-500℃, 70-85% reduction); then cold-roll to 0.15mm, 60-75% reduction; then roll the foil to 0.02-0.09mm after 330-380℃×2h, and the foil rolling processing rate is >40%. This patent adopts the hot rolling blanking path for production, does not contain Si element to prevent the formation of hard and brittle phases, adds La to refine grains and strengthen, and does not involve V element. The prepared aluminum foil has a tensile strength of ≥215MPa and an elongation of ≥1.7%; after the aluminum foil is kept at a constant temperature of 140°C or 160°C for 10 hours, the tensile strength is greater than 205MPa and the elongation is greater than 3.8%.

[0004] Chinese patent CN202011137836.8 discloses a high-performance aluminum foil for lithium-ion batteries and a production method. The aluminum foil composition includes Si≤0.1wt%, Fe: 0.15~0.3wt%, Cu: 0.08~0.15wt%, Mn≤0.01wt%, Mg≤0.03wt%, Zn≤0.03wt%, Ti: 0.02~0.03wt%, V≤0.03wt%. The basic process flow is: melt the ingot, hot roll it after annealing (520~560℃×10~15h), and the rolling temperature is 480~530℃; then cold roll it to 0.22~0.3mm, and finally roll the foil to 8~20μm and cut it into finished products. The patent adopts the hot rolling blanking path for production, and does not mention the control effect of the V element and its content range. The tensile strength of the prepared aluminum foil is 254MPa.

[0005] Chinese patent CN202010802903.7 discloses an aluminum foil for 1235D lithium battery and its preparation method. The aluminum foil composition includes Si: 0.01-0.25wt%, Fe: 0.41-0.47wt%, Cu: 0.14-0.2wt%, Mn: 0.01-0.04wt%, Mg: 0.01-0.03wt%, Zn: 0.01-0.05wt%, Ti: 0.01-0.03wt%, V: 0.01-0.05wt%. The basic process flow is: 7-8mm strip billet is smelted and cast, and cold rolled to a thickness of 1.5-1.8mm; during the retreat: the material temperature is 330-380℃×2h, and the furnace temperature drops to 300±20℃ when the 1 / 2 furnace door is opened and discharged; then cold rolled to 0.36mm, and finally foil rolled, slit, and corona are used to obtain the finished aluminum foil. This patent adopts the casting and rolling process for production, and does not mention the control effect of the V element and its content range. It contains a higher Cu content to improve the alloy properties. The tensile strength of the prepared aluminum foil is ≥235MPa and the elongation is ≥2%.

[0006] Chinese patent CN202110179650.7 discloses a high-surface, high-performance, high-precision aluminum foil for automotive batteries and its preparation process. The aluminum foil contains Si: 0.04~0.1wt%, Fe: 0.3~0.45wt%, Cu: 0.06~0.1wt%, Mn: 0.0005~0.003wt%, Mg: 0.025~0.05wt%, Zn: 0.002~0.01wt%, Ti: 0.01~0.03wt%, V: 0.005~0.03wt%, Cr: 0.0005~0.005wt%; Fe / Si: 5~10, Cu / Mg: 2~4. The basic process flow is: smelting → DC casting (480-640mm thickness) → homogenization (1-2℃ / min heating 520-565℃×7-9h, 0.5-1.5℃ / min cooling) → hot rolling (opening rolling 500-540℃, final rolling 290-330℃, 5-9mm) → cold rolling (0.24mm) → finishing rolling (0.012-0.02mm). This patent adopts the hot rolling billet production path, does not mention the V element and its content range control effect, adds Cu element to improve strength, and the tensile strength of the prepared aluminum foil is ≥190MPa and the surface tension is ≥34 dynes. Summary of the invention

[0007] The object of the present invention is to provide a 1XXX aluminum alloy billet for high-strength power battery foil, a preparation method and an application thereof, which ensures that the 1XXX aluminum alloy has high strength while also having good plasticity and conductivity. The aluminum alloy billet has a tensile strength of 180-220 MPa and an elongation of ≥4%. The obtained battery foil has a tensile strength of ≥290 MPa, an elongation of ≥3%, and a resistivity of ≤3.1 μΩ·cm, which can be used for power battery current collectors, can meet the demand for further thinning of power battery current collector aluminum foil for increased strength, and reduce the risk of coating breakage.

[0008] To achieve the above object, the technical solution of the present invention is:

[0009] A 1XXX aluminum alloy billet for high-strength power battery foil, the composition mass percentage of which is: Si: 0.05-0.08%, Fe: 0.26-0.29%, V: 0.04-0.07%, Ti: 0.015-0.025%, Mn: 0.01-0.05% or Cr: 0.01-0.05% or two thereof, the balance includes Al and other unavoidable impurities, and also needs to meet the following requirements at the same time:

[0010] The atomic ratio of Fe / (Si+V) is controlled at: 1.1-2.0;

[0011] V+Ti+Mn+Cr≤0.13%.

[0012] Further, the balance is Al and other inevitable impurities.

[0013] The metallographic structure of the aluminum alloy billet of the present invention is a mixed structure of recrystallized grains and slender fiber structures, granular α-AlFeSi and α-AlFeMnSi compounds, dispersed α-AlFeSi and AlV precipitation phases, and a small amount of Al3Fe and AlFeSi precipitation phases.

[0014] Preferably, the amount of the granular α-AlFeSi and α-AlFeMnSi compounds is 65-75%.

[0015] Preferably, the amount of the dispersed α-AlFeSi and AlV precipitated phases is 15-25%.

[0016] Preferably, the amount of the Al3Fe precipitated phase is less than 10%.

[0017] Preferably, the amount of AlFeSi precipitated phase is less than 3%.

[0018] The aluminum alloy blank of the present invention has a tensile strength of 180-220 MPa and an elongation of ≥4%.

[0019] In the composition design of the 1XXX aluminum alloy billet for high-strength power battery foil of the present invention:

[0020] Si and Fe are the main elements in 1XXX aluminum alloy. The present invention controls the Si content to 0.05-0.08wt% and the Fe content to 0.26-0.29wt%, so that a part of Al, Si and Fe forms a second phase (AlFe, AlFeSi, etc.) during the casting process, which serves as a recrystallization nucleation point, is conducive to obtaining fine annealing grains and improving alloy properties; the other part forms a dispersed phase (α-AlFeSi), which improves the strength of the material by hindering dislocation movement. If the Si and Fe content is too low, the purity requirements of the raw materials will be increased, which will increase the cost; if the content is too high, it is easy to form coarse compounds during casting, which are difficult to break in subsequent processing, which will reduce the elongation of the alloy and become a pinhole source.

[0021] V, utilizing the dispersion precipitation of V element dissolved in the alloy matrix during annealing, plays a role of dispersion strengthening, and at the same time helps to refine the annealing grains. When the V content is lower than 0.04wt%, the precipitated dispersed phase is small, and the strengthening effect is minimal. When the content is too high, it cannot be completely dissolved in the aluminum matrix during semi-continuous casting, and coarse compounds will be formed during casting, which is not conducive to the elongation and pinhole control of the aluminum foil. Therefore, the present invention controls the V content to 0.04-0.07wt%.

[0022] At the same time, the present invention controls the Fe / (Si+V) atomic ratio to be 1.1-2.0. The addition of an appropriate amount of V can change the precipitation temperature of the α-AlFeSi phase, and a small amount of V solid-dissolved in the AlFeSi compound can promote the precipitation of the α-AlFeSi phase, thereby increasing the amount of the α-AlFeSi phase by about 20%. The α-AlFeSi phase can be transformed into fine particles during the soaking process, and broken into dispersed fine particles during the rolling process, which is beneficial to the improvement of strength without adversely affecting the elongation. When the Fe / (Si+V) atomic ratio is ≥2.0, excessive Fe content will easily cause the formation of needle-shaped Al3Fe phases, reduce the elongation of the material, and increase pinholes. When the Fe / (Si+V) atomic ratio is ≤1.1, it is easy to cause the formation of coarse β-AlFeSi phases and V-containing phases, which is not conducive to the improvement of elongation.

[0023] Ti, a proper amount of Ti can refine the grains of the casting strip and improve the material processing performance. Too high a Ti content can easily cause slag inclusions to become the source of pinholes in the aluminum foil and is not conducive to the electrical conductivity. Therefore, the present invention controls the Ti content to be 0.015-0.025wt%.

[0024] Mn, an appropriate amount of Mn can change the type and morphology of the Fe-containing phase, which is conducive to the formation of α-AlFeSi precipitation phase and inhibits the formation of coarse β-AlFeSi phase, and can reduce the adverse effects of the Fe-containing phase on the elongation and pinhole control of the aluminum foil. The addition of Mn will increase the starting precipitation temperature of α-AlFeSi, and the starting precipitation temperature will continue to increase with the increase of the content. When the Mn content is greater than 0.05%, α-AlFeSi will begin to precipitate at around 550°C. At this time, the precipitated phase is easy to grow in the subsequent high-temperature process, and contributes little to the dispersion strengthening effect. At the same time, it will reduce the subsequent precipitation amount and reduce the number of fine precipitation phases. If the content is too low, the effect is limited; if the content is too high, it will have an adverse effect on the electrical conductivity of the aluminum foil. Therefore, the present invention can choose to add and control the Mn content to 0.01-0.05wt%.

[0025] Cr, a proper amount of Cr can form a dispersed phase, supplement the dispersion strengthening and grain refinement. If the content is too high, it is easy to form coarse AlCr and AlCrSi compounds during casting. The coarse compounds are not easy to break and will be left in the subsequent aluminum foil, which is not conducive to the elongation and pinhole control of the aluminum foil. Therefore, the present invention can selectively add and control the Cr content to 0.01-0.05wt%.

[0026] The solid solution of V, Ti, Mn and Cr in the aluminum matrix will seriously affect the conductivity of the alloy. To ensure the resistivity of the aluminum foil ≤3.1μΩ·cm, V+Ti+Mn+Cr needs to be controlled to ≤0.13wt%.

[0027] The method for preparing the 1XXX aluminum alloy for high-strength power battery foil of the present invention comprises the following steps:

[0028] 1) Smelting according to the above composition ratio, degassing and deslagging, and casting into flat ingots;

[0029] 2) Heat evenly

[0030] The flat ingot is milled, and then the temperature is raised to 500-510°C at a rate of 50-100°C / h and kept at this temperature for 1-2 hours, and then the temperature is raised to 585-600°C at a rate of 20-35°C / h and kept at this temperature for 5-8 hours. After the holding period, the temperature is lowered to 480-520°C at a rate of 30-40°C / h and kept at this temperature for 2-4 hours;

[0031] 3) Hot rough rolling

[0032] Final rolling temperature 440~480℃;

[0033] 4) Hot finishing rolling

[0034] The reduction of each pass is 50-60%, the hot finishing rolling start temperature is 420-450°C, and the coiling temperature is 320-340°C;

[0035] 5) Cold rolling

[0036] After cold rolling, a hard foil blank is obtained, the online plate shape is ≤10I, the reduction amount of each pass is 50-60%, and the final cold rolling temperature is 100-130°C.

[0037] Preferably, in step 3), the number of hot rough rolling passes is controlled to be 13 to 17 passes, wherein the reduction amount of each of the 5th to 10th passes is controlled to be 50 to 60 mm.

[0038] Preferably, in step 3), the thickness of the slab after hot rough rolling is 30 to 40 mm.

[0039] Preferably, in step 4), the hot rough-rolled slab is continuously rolled through 3 or 4 stands to a thickness of 2 to 3.5 mm.

[0040] Preferably, the thickness of the foil after cold rolling is 0.2 to 0.3 mm.

[0041] The present invention also provides a high-strength power battery foil, which is prepared by using the aluminum alloy blank through foil rolling, slitting and cleaning processes.

[0042] The battery foil of the present invention has a tensile strength of ≥290 MPa, an elongation of ≥3%, and a resistivity of ≤3.1 μΩ·cm.

[0043] In the method for preparing the 1XXX aluminum alloy for high-strength power battery foil of the present invention:

[0044] During the smelting process, the melt is degassed and deslaged. After online degassing, the hydrogen content is no more than 0.11ml / 100gAl. The melt is filtered by plate and tube to cast a flat ingot. This can effectively reduce the adverse effects of gas and slag on the elongation and pinhole rate of battery foil.

[0045] The soaking treatment is carried out in steps:

[0046] In the first stage, the temperature is raised to 500-510°C at a rate of 50-100°C / h and kept at this temperature for 1-2h: AlV and α-AlFeSi will precipitate at temperatures below 500°C, and the amount of precipitation increases rapidly as the temperature decreases and the heating time increases. The first step of rapid heating causes the ingot to heat up rapidly, which can reduce the precipitation of compounds such as AlV, α-AlFeSi and AlFe during this heating process. The precipitated phase at this stage will grow in the subsequent thermal process and affect the elongation of the material or become a source of pinholes, so it is necessary to suppress precipitation as much as possible; at the same time, rapid heating to a higher temperature and keeping warm can improve efficiency.

[0047] In the second stage, the temperature is raised to 585-600℃ at a rate of 20-35℃ / h and kept at this temperature for 5-8h: The second step of slow heating and high temperature keeping is conducive to the full transformation and spheroidization of the flake, lath or needle-shaped coarse compounds (AlFeSi, etc.) formed during the casting process into particles or back to the matrix, reducing the segregation of coarse compounds, avoiding the adverse effects of coarse compounds on the elongation of the material and reducing the pinhole rate. The addition of Mn will increase the precipitation temperature of α-AlFeSi. Keeping at 585-600℃ can avoid the precipitation starting temperature of α-AlFeSi and AlV, thereby preventing the adverse effects of precipitation growth in the high temperature stage.

[0048] After the third stage of heat preservation, the temperature is lowered to 480-520℃ at a rate of 30-40℃ / h and kept for 2-4h: The third step of cooling and heat preservation promotes the precipitation of Fe, Si, Mn, V, Cr and other elements in dispersed phase, which helps to improve the strength and conductivity of the subsequent aluminum foil; at the same time, it is kept at 480-520℃ for 2-4h. The control of the heat preservation time range can not only ensure that the ingot reaches the same temperature as a whole, but also prevent the growth of the precipitation phase due to too long heat preservation time, and avoid the risk of large-size phase becoming a pinhole source; at the same time, the heat preservation temperature of 480-520℃ can meet the requirements of the hot rough rolling start temperature, which is conducive to energy saving. High temperature is not conducive to hot rolling surface control; low temperature makes hot rolling difficult.

[0049] Hot rough rolling: The hot rough rolling of the flat ingot is finished to a thickness of 30-40mm to ensure the appropriate thickness at the entrance of the finishing rolling. The final rolling temperature is 440-480℃ to ensure the appropriate start temperature of the finishing rolling and meet the temperature requirements of the subsequent finishing rolling curling. The number of hot rough rolling passes is controlled at 13-17 passes, and the reduction of each pass of the 5th-10th pass is 50-60mm. By increasing the deformation of a single rolling pass, the compound can be broken as much as possible, which is beneficial to the elongation and pinhole control, and provides more energy storage and nucleation particles for the recrystallization of the hot finishing rolling curling, which is beneficial to obtain fine recrystallized grains.

[0050] Hot finishing rolling: The hot finishing rolling start temperature is 420-450℃, the coiling temperature is 320-340℃, and the final rolling thickness is 2-3.5mm, which is convenient for subsequent cold rolling to obtain aluminum foil blanks with suitable strength and elongation. Hot finishing rolling starts at 420-450℃, which is conducive to obtaining the target curling temperature. The coiling temperature is 320-340℃, which is within the material recrystallization temperature range. The compounds obtained by hot rolling can be used as recrystallization nucleation particles, so that the hot-rolled plate obtains a mixed structure of fine recrystallized grains + slender fiber structures, which is conducive to improving the strength and elongation of the hot-rolled plate, so as to obtain aluminum foil blanks with the expected target performance in the future; at the same time, this temperature range is conducive to the precipitation of dispersed phases such as AlV, α-AlFeSi, and AlCr during the cooling process of the coil, so as to achieve the subsequent dispersion strengthening effect on the aluminum foil. Low temperature or large thickness will cause the aluminum foil blank to have high strength and low elongation. When the temperature is higher than 340℃, the recrystallized grains will grow significantly, which is not conducive to the performance and surface of the aluminum foil. The reduction of each pass of hot finishing rolling is controlled within the range of 50-60%. The maximum deformation rate of each pass can promote the crushing of compounds, which is beneficial to the elongation and pinhole control, and increase the number of compounds used for recrystallization nucleation. If the reduction of each pass is too large, the mill capacity will be difficult to meet the requirements and the plate shape control will be affected. If the reduction of each pass is small, the production efficiency will be affected.

[0051] Cold rolling: The thickness of the cold rolled billet is 0.2-0.3mm, which can ensure the reasonable matching of the subsequent strength and elongation of the aluminum foil; if the billet is too thick, the subsequent aluminum foil rolling amount will be too high, making the aluminum foil strength too high and the elongation too low, which cannot meet the requirements. When the online plate shape is ≤10I, the uniformity of the aluminum foil thickness can be guaranteed and the risk of foil breaking can be reduced. The reduction of each cold rolling pass is 50-60%, which further breaks the compound and improves the rolling efficiency. The final rolling temperature is controlled at 100-130℃. Through the self-recovery of the billet, the internal structure is improved, and the ductility of the material is improved without reducing or slightly reducing the strength.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The present invention is based on the traditional 1XXX aluminum alloy. By adding a small amount of Si, Fe, and Cr elements, combined with the addition of appropriate amounts of V and Mn elements, and controlling the Fe / (Si+V) atomic ratio to 1.1-2.0, the amount of α-AlFeSi and α-AlFeMnSi precipitation phases is increased, and the precipitation of dispersed fine AlV and other precipitation phases is combined to inhibit the formation of coarse β-AlFeSi and needle-shaped Al3Fe phases, thereby promoting the improvement of the strength of the aluminum alloy while avoiding the adverse effect on the elongation. The amount of granular α-AlFeSi and α-AlFeMnSi compounds on the obtained aluminum alloy is 65-75%, the amount of dispersed α-AlFeSi and AlV precipitation phases is 15-25%, the amount of Al3Fe precipitation phase is less than 10%, and the amount of AlFeSi precipitation phase is less than 3%.

[0054] At the same time, by controlling V+Ti+Mn+Cr≤0.13wt%, the V, Ti, Mn, and Cr elements can play a role in strength while reducing the adverse effects of each element on conductivity, so that the resistivity of the prepared battery foil is ≤3.1μΩ·cm, thereby meeting the conductivity requirements of the battery collector, thereby obtaining an ultra-high strength 1XXX aluminum alloy with better overall performance.

[0055] Based on the composition design, the present invention adopts a multi-step heat treatment. The first stage adopts rapid heating and short-time heat preservation to inhibit the precipitation of phases such as AlV, α-AlFeSi and AlFe. The second stage continues with slow heating and high-temperature heat preservation to reduce the presence of coarse compounds. The third stage cools down and keeps warm to promote the precipitation of alloy elements in dispersed phases and avoid the coarsening of precipitated phases. While improving the strength and electrical conductivity, it reduces the adverse effects on the elongation of the material and reduces the pinhole rate. Combined with the subsequent hot finishing and cold rolling processes, the material is controlled to form a mixed structure of recrystallized grains + slender fiber structures, which promotes the further precipitation of dispersed phases and ensures that aluminum alloy billets with high strength and elongation are obtained. The aluminum foil billet prepared by the present invention has a tensile strength of 180 to 220 MPa and an elongation of ≥4%, which is beneficial to the subsequent aluminum foil rolling.

[0056] The battery foil prepared from the blank has a tensile strength of ≥290MPa, an elongation of ≥3%, and a resistivity of ≤3.1μΩ·cm, which can meet the strength requirements of further thinning of the power battery current collector aluminum foil, reduce the risk of coating breakage, and meet the current collector requirements of power lithium batteries and sodium batteries. The strength of the battery foil prepared from the existing 1XXX aluminum alloy can only reach about 250MPa at most. DETAILED DESCRIPTION

[0057] The present invention is further illustrated by the following examples, but this is not a limitation of the present invention. Those skilled in the art may make modifications or improvements based on the basic idea of ​​the invention, but as long as they do not deviate from the basic idea of ​​the present invention, they are all within the scope of the present invention.

[0058] The chemical composition of the aluminum alloy strips of the embodiment of the present invention and the comparative example is shown in Table 1, and the remainder of the composition is Al and other inevitable impurities. The process parameters of the preparation method of the embodiment of the present invention are shown in Table 2, and the properties of the prepared aluminum foil are shown in Table 3.

[0059] The aluminum alloy billets prepared in Examples 1-6 and Comparative Examples 1-5 were further rolled into aluminum foils of a desired thickness (10-20 μm). The performance results of the prepared aluminum alloy billets and aluminum foils are shown in Table 3.

[0060] As can be seen from Table 3, the aluminum alloy blanks prepared in Examples 1-6 have a tensile strength of 180-220 MPa and an elongation of ≥4%. The aluminum alloy blanks prepared above are further rolled into aluminum foils of the required thickness (10-20 μm), and the obtained aluminum foils have a tensile strength of ≥290 MPa, an elongation of ≥3%, and a resistivity of ≤3.1 μΩ·cm, which can be used for power battery current collectors, meeting the demand for further thinning of power battery current collector aluminum foils for increased strength, and reducing the risk of coating breakage.

[0061] In Comparative Example 1, the added V element is relatively high, and the total amount of V+Ti+Mn+Cr reaches 0.185%, which exceeds the 0.13% specified in the present invention. Although the same process as the present invention is used, the strength of the prepared aluminum foil blank and the finished battery foil can meet the requirements, but the elongation of the aluminum foil is low and the resistivity is high.

[0062] Comparative Example 2 does not contain the V element, the Fe / (Si+V) atomic ratio is relatively high, and the total amount of Ti+Mn+Cr reaches 0.145%, which exceeds the 0.13% specified in the present invention. Although the same process as the present invention is used, the finished aluminum foil has a low elongation and a high resistivity.

[0063] In Comparative Example 3, the Fe and Si contents are relatively high, and no V element is contained. The total amount of V+Ti+Mn+Cr reaches 0.220%, which exceeds the 0.13% specified in the present invention. Although the same process as the present invention is used, the elongation of the prepared finished aluminum foil is relatively low and the resistivity is relatively high.

[0064] Comparative Example 4 uses the same ingredients as Example 1 of the present invention, but the process does not use step-by-step heating treatment during the heat treatment. The elongation of the aluminum foil blank finally obtained can meet the requirements, but the strength of the finished battery foil is low and the resistivity is high.

[0065] Comparative Example 5 uses the same ingredients as Example 6 of the present invention, but the process does not use step-by-step heating treatment during the heat treatment, and the finished battery foil has a low elongation and a high resistivity.

[0066]

[0067]

[0068]

[0069]

Claims

1. A 1XXX aluminum alloy billet for high-strength power battery foil, wherein the composition by mass percentage is: Si: 0.05-0.08%, Fe: 0.26-0.29%, V: 0.04-0.07%, Ti: 0.015-0.025%, Mn: 0.01-0.05% or Cr: 0.01-0.05% or two thereof, the balance includes Al and other unavoidable impurities, and also needs to meet the following requirements: The atomic ratio of Fe / (Si+V) is controlled at: 1.1-2.0; V+Ti+Mn+Cr≤0.13%.

2. The 1XXX aluminum alloy billet for high-strength power battery foil according to claim 1, characterized in that: The balance is Al and other inevitable impurities.

3. The 1xxx aluminum alloy billet for high-strength power battery foil according to claim 1 or 2, characterized in that: The metallographic structure of the aluminum alloy billet is a mixed structure of recrystallized grains and slender fiber structures, on which granular α-AlFeSi and α-AlFeMnSi compounds, dispersed α-AlFeSi and AlV precipitation phases, and a small amount of Al3Fe and AlFeSi precipitation phases are distributed.

4. The 1XXX aluminum alloy billet for high-strength power battery foil according to claim 3, characterized in that: The amount of the granular α-AlFeSi and α-AlFeMnSi compounds is 65-75%.

5. The 1XXX aluminum alloy billet for high-strength power battery foil according to claim 3, characterized in that: The amount of the dispersedly distributed α-AlFeSi and AlV precipitated phases is 15-25%.

6. The 1XXX aluminum alloy blank for high-strength power battery foil according to claim 3, characterized in that: The amount of the Al3Fe precipitated phase is less than 10%.

7. The 1XXX aluminum alloy billet for high-strength power battery foil according to claim 3, characterized in that: The amount of AlFeSi precipitated phase is less than 3%.

8. The 1XXX aluminum alloy billet for high-strength power battery foil according to any one of claims 1 to 7, characterized in that: The aluminum alloy blank has a tensile strength of 180-220 MPa and an elongation of ≥4%.

9. The method for preparing the 1XXX aluminum alloy billet for high-strength power battery foil according to any one of claims 1 to 8, characterized in that: The steps include: 1) melting according to the composition ratio of claim 1 or 2, and performing degassing and deslagging treatment, and casting into a flat ingot; 2) Heat evenly The flat ingot is milled, and then the temperature is raised to 500-510°C at a rate of 50-100°C / h and kept at this temperature for 1-2 hours, and then the temperature is raised to 585-600°C at a rate of 20-35°C / h and kept at this temperature for 5-8 hours. After the holding period, the temperature is lowered to 480-520°C at a rate of 30-40°C / h and kept at this temperature for 2-4 hours; 3) Hot rough rolling Final rolling temperature 440~480℃; 4) Hot finishing rolling The reduction of each pass is 50-60%, the hot finishing rolling start temperature is 420-450°C, and the coiling temperature is 320-340°C; 5) Cold rolling After cold rolling, a hard foil blank is obtained, the online plate shape is ≤10I, the reduction amount of each pass is 50-60%, and the final cold rolling temperature is 100-130°C.

10. The preparation method according to claim 9, characterized in that: In step 3), the hot rough rolling passes are controlled to be 13 to 17 passes, wherein the reduction amount of each pass in the 5th to 10th passes is controlled to be 50 to 60 mm. Preferably, the thickness of the slab after hot rough rolling is 30 to 40 mm.

11. The preparation method according to claim 9, characterized in that: In step 4), the hot rough rolled slab is hot finished rolled to a thickness of 2 to 3.5 mm by means of 3 or 4 stands.

12. The preparation method according to claim 9, characterized in that: The thickness of the foil after cold rolling is 0.2-0.3 mm.

13. A high-strength power battery foil, characterized in that: The aluminum alloy billet is prepared by using the aluminum alloy billet described in any one of claims 1 to 8 or the aluminum alloy billet obtained by the preparation method described in any one of claims 9 to 12 through foil rolling, slitting and cleaning steps.

14. The high-strength power battery foil according to claim 13, characterized in that: The battery foil has a tensile strength of ≥290 MPa, an elongation of ≥3%, and a resistivity of ≤3.1 μΩ·cm.

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