Ultrahigh-strength 13-micron battery aluminum foil and preparation method thereof

Abstract

The invention discloses an ultrahigh-strength 13-micron battery aluminum foil and a preparation method thereof, and belongs to the technical field of battery aluminum foils. The battery aluminum foil comprises the following alloy elements in percentage by mass: 0.23 to 0.27 percent of Si, 0.44 to 0.50 percent of Fe, 0.185 to 0.205 percent of Cu, 0.86 to 0.90 percent of Mn, 1.19 to 1.24 percent of Mg, less than or equal to 0.04 percent of Cr, less than or equal to 0.06 percent of Zn, 0.01 to 0.025 percent of Ti and the balance of Al. The preparation method comprises the following steps: (1) smelting and casting; (2) homogenizing; (3) hot rolling: performing multi-pass hot rolling on the homogenized aluminum alloy cast ingot to obtain a hot-rolled coiled material, and controlling the finish rolling temperature to be greater than or equal to 330 DEG C; (4) cold rolling: after the hot-rolled coiled material is cooled, performing multi-pass cold rolling to obtain a cold-rolled finished product, and annealing the cold-rolled finished product after cold rolling; (5) foil rolling is carried out, after the annealed cold-rolled finished product is cooled, multi-pass foil rolling is carried out, and primary foil rolling intermediate annealing is carried out between foil rolling passes; and (6) slitting to obtain the battery aluminum foil. The ultrahigh-strength tensile battery aluminum foil is obtained by combining alloy component regulation and control with a preparation process.

Description

Technical Field

[0001] The invention relates to the technical field of battery aluminum foil, and in particular to an ultra-high strength 13μm battery aluminum foil and a preparation method thereof. Background Art

[0002] The lithium-ion battery industry usually uses rolled aluminum foil as the positive electrode collector. With the development of lithium-ion batteries, higher requirements are also put forward for the quality and performance of battery foil used for its positive electrode collector. In addition to the continuous improvement of plate quality, surface quality, and surface cleanliness, it is also required to have higher mechanical properties. At present, the 13μm battery foil products made of 1060 and 1100 alloys using conventional processes usually have a tensile strength of 190 to 240MPa. The tensile strength of 1100 alloy can reach 280MPa under special production processes. Although it has relatively high strength, it still cannot meet the demand of high-end lithium-ion batteries for ultra-high strength tensile battery foil. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides an ultra-high strength 13μm battery aluminum foil and a preparation method thereof, and obtains an ultra-high strength tensile battery aluminum foil by combining alloy composition regulation with preparation technology.

[0004] The technical solution adopted by the present invention is:

[0005] On the one hand, the present invention provides an ultra-high strength 13μm battery aluminum foil, comprising the following alloy elements in percentage by mass: Si 0.23-0.27%, Fe 0.44-0.50%, Cu 0.185-0.205%, Mn 0.86-0.90%, Mg1.19-1.24%, Cr≤0.04%, Zn≤0.06%, Ti 0.01-0.025%, the remainder being Al and unavoidable impurity elements, and the total content of impurity elements being ≤0.15%.

[0006] On the other hand, the present invention provides a method for preparing an ultra-high strength 13 μm battery aluminum foil, comprising the steps of:

[0007] (1) Melting and casting: weighing corresponding raw materials according to alloy components and proportions, and putting them into a melting furnace for melting. After the aluminum alloy liquid is completely melted, refining is performed, and pure aluminum melt is obtained by online SNIF degassing and online filtration. The aluminum melt is cast to obtain an aluminum alloy ingot;

[0008] (2) homogenization, placing the aluminum alloy ingot into a heating furnace for homogenization treatment;

[0009] (3) hot rolling, wherein the homogenized aluminum alloy ingot is subjected to multiple hot rolling passes to obtain a hot rolled coil, and the final rolling temperature is controlled to be ≥330°C;

[0010] (4) cold rolling, after the hot rolled coil is cooled, performing multiple cold rolling passes to obtain a cold rolled product, and annealing the cold rolled product after cold rolling;

[0011] (5) foil rolling, after the annealed cold-rolled product is cooled, multiple passes of foil rolling are performed, and an intermediate foil rolling annealing is performed between the foil rolling passes;

[0012] (6) Cutting to obtain battery aluminum foil.

[0013] Furthermore, the homogenization process in step (2) is 605±10℃*5~10h+550±10℃*0~4h.

[0014] Furthermore, in step (3), the thickness of the hot-rolled coil is 2.0 to 2.1 mm.

[0015] Furthermore, in step (4), there are three cold rolling passes in total, and the thickness of the cold rolled product is 0.21 to 0.25 mm.

[0016] Furthermore, in the step (4), the annealing process of the cold-rolled finished product is 360±10°C*6-8h.

[0017] Furthermore, the foil rolling in step (5) includes: the first pass, pressing from 0.21-0.25 mm to 0.12 mm; the second pass, pressing to 65 μm; the third pass, pressing to 32 μm; the fourth pass, pressing to 19 μm; and the fifth pass, pressing to 13 μm.

[0018] Furthermore, in the step (5), foil rolling intermediate annealing is performed after the third pass, and the foil rolling intermediate annealing process is 300±10°C*6~8h.

[0019] The beneficial effects of the present invention are:

[0020] The present invention provides an ultra-high strength 13μm battery aluminum foil and a preparation method thereof. By optimizing the alloy composition, the contents of Si, Cu, Mn, and Mg alloy elements are mainly increased, and the alloying degree of the aluminum alloy is improved. The main strengthening phases are MnAl6 and (FeMn)Al6, which can effectively hinder dislocation movement, thereby improving the strength and hardness of the alloy, while maintaining good corrosion resistance and machinability; in addition, after the present invention optimizes and adjusts the alloy composition, the alloying degree is improved, the strength and hardness of the battery foil are high, and it also brings difficulties to the rolling process. Therefore, the present invention also optimizes the preparation process, mainly annealing the cold-rolled finished product after cold rolling, and adding an intermediate annealing in the middle pass of foil rolling to ensure that the rolling process proceeds smoothly. The battery aluminum foil prepared by the present invention has a tensile strength of up to 320MPa, and has ultra-high tensile strength. DETAILED DESCRIPTION

[0021] The present invention provides an ultra-high strength 13μm battery aluminum foil and a preparation method thereof. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] The invention provides an ultra-high strength 13μm battery aluminum foil, which comprises the following alloy elements in percentage by mass: Si 0.23-0.27%, Fe 0.44-0.50%, Cu 0.185-0.205%, Mn 0.86-0.90%, Mg 1.19-1.24%, Cr≤0.04%, Zn≤0.06%, Ti 0.01-0.025%, the remainder being Al and unavoidable impurity elements, and the total content of the impurity elements being ≤0.15%.

[0023] The present invention mainly increases the content of Si, Cu, Mn and Mg alloy elements, improves the alloying degree of aluminum alloy, and can form MnAl6, (FeMn)Al6, (Al, Fe, Mn, Si) quaternary phase, (Al, Mn, Si) ternary phase, (Al, Mn, Mg, Fe) quaternary phase, etc. in the battery aluminum foil finished product, and solid dissolves Mg2Si phase, wherein the main strengthening phases are MnAl6 and (FeMn)Al6, which can effectively hinder dislocation movement, thereby improving the strength and hardness of the alloy, while maintaining good corrosion resistance and machinability.

[0024] After the alloy composition is adjusted in the present invention, the alloying degree is improved, and the strength and hardness of the battery foil are improved, but it also brings difficulties to the rolling process. Therefore, the preparation process must be improved, especially the rolling process.

[0025] On the basis of adjusting the alloy composition, the present invention also provides a method for preparing an ultra-high strength 13 μm battery aluminum foil for the aluminum alloy with the alloy composition, comprising the steps of:

[0026] (1) Melting and casting: weighing corresponding raw materials according to alloy components and proportions, and putting them into a melting furnace for melting. After the aluminum alloy liquid is completely melted, it is refined, and a pure aluminum melt is obtained by online SNIF degassing and plate filtration and tubular filtration. The aluminum melt is cast to obtain an aluminum alloy ingot;

[0027] (2) homogenization, placing the aluminum alloy ingot into a heating furnace for homogenization treatment. Specifically, the homogenization treatment process is 605±10℃*5~10h+550±10℃*0~4h;

[0028] (3) hot rolling, wherein the aluminum alloy ingot after homogenization is directly subjected to multiple hot rolling to obtain a hot rolled coil, and the final rolling temperature is controlled to be ≥330°C; the initial thickness of the hot rolling is 596 mm, and after 15 to 19 hot rough rolling passes and 4 hot finish rolling passes, the hot rolled coil is obtained to have a finished thickness of 2.0 to 2.1 mm and a state of F;

[0029] (4) cold rolling, after the hot-rolled sheet is cooled, multiple cold rolling passes are performed to obtain a cold-rolled product, and the cold-rolled product is annealed after cold rolling; the cold rolling passes are three in total, and the cold-rolled product thickness is 0.21-0.25 mm, and the cold-rolled product is annealed, and the cold-rolled product annealing process is 360±10℃*6-8h, preferably 360℃*7h; that is, the cold rolling process is: 2.0-2.1mm / F→three passes to 0.21-0.25mm / H19→0.21-0.25mm / O state;

[0030] (5) Foil rolling: after the annealed cold-rolled product is cooled, multiple passes of foil rolling are performed, and a foil rolling intermediate annealing is performed between the foil rolling passes; the foil rolling specifically includes five passes: the first pass, from 0.21-0.25 mm to 0.12 mm; the second pass, to 65 μm; the third pass, to 32 μm; the fourth pass, to 19 μm; the fifth pass, to 13 μm, and foil rolling intermediate annealing is performed after the third pass, and the foil rolling intermediate annealing process is 300±10℃*6-8h, preferably 300℃*7h; that is, the foil rolling process is: 0.21-0.25mm / O state→0.12mm / H14→0.065mm / H18→0.032mm / H19→0.032mm / O state→0.019mm / H14→0.013mm / H14;

[0031] (6) Cutting to obtain battery aluminum foil.

[0032] In the present invention, the cold-rolled finished product needs to be annealed in the above step (4) to eliminate work hardening, restore the plasticity and cold deformation ability of the material, and refine the grains, adjust the structure, eliminate internal structural defects, and prepare for the subsequent foil rolling process. In addition, since the alloying degree of the aluminum alloy in the present invention is high, the tensile strength increases rapidly under the same processing rate during the rolling process. Therefore, an intermediate annealing is added during the aluminum foil rolling process to prevent the work hardening degree from being too high, resulting in excessive rolling force and difficulty in foil rolling thinning.

[0033] Example 1

[0034] This embodiment provides a method for preparing an ultra-high strength 13 μm battery aluminum foil, comprising the steps of:

[0035] (1) Melting and casting: the alloy elements are prepared according to the following mass percentages: Si 0.27%, Fe 0.50%, Cu 0.20%, Mn 0.90%, Mg 1.24%, Cr 0.03%, Zn 0.05%, Ti 0.020%, and the balance is Al. The raw materials are put into a melting furnace for melting. After the melting is complete, the aluminum alloy liquid is refined. After online SNIF degassing and plate filtration and tubular filtration, a pure aluminum melt is obtained. The aluminum melt is cast to obtain an aluminum alloy ingot;

[0036] (2) homogenization, placing the aluminum alloy ingot into a heating furnace for homogenization treatment. Specifically, the homogenization treatment process is 605°C*10h+550°C*2h;

[0037] (3) hot rolling, directly subjecting the aluminum alloy ingot after homogenization to multiple hot rolling to obtain hot rolled plates, and controlling the final rolling temperature to be ≥330°C; the initial thickness of hot rolling is 596 mm, and after 15 to 19 hot rough rolling passes and 4 hot finish rolling passes, the thickness of the hot rolled product is 2.1 mm, and the state is F state;

[0038] (4) Cold rolling: after the hot-rolled sheet is cooled, multiple cold rolling passes are performed to obtain a cold-rolled product, and the cold-rolled product is annealed after cold rolling; the cold rolling passes are three in total, and the cold-rolled product thickness is 0.25 mm, and the cold-rolled product is annealed, and the cold-rolled product annealing process is 360°C*7h; that is, the cold rolling process is: 2.1mm / F→three passes to 0.25mm / H19→0.25mm / O state;

[0039] (5) Foil rolling: after the annealed cold-rolled product is cooled, multiple passes of foil rolling are performed, and a foil rolling intermediate annealing is performed between the foil rolling passes; the foil rolling specifically includes five passes: the first pass, from 0.25mm to 0.12mm; the second pass, to 65μm; the third pass, to 32μm; the fourth pass, to 19μm; the fifth pass, to 13μm, and after the third pass, foil rolling intermediate annealing is performed, and the foil rolling intermediate annealing process is 300℃*7h; that is, the foil rolling process is: 0.25mm / O state→0.12mm / H14→0.065mm / H18→0.032mm / H19→0.032mm / O state→0.019mm / H14→0.013mm / H14;

[0040] (6) Cutting to obtain battery aluminum foil.

[0041] The battery aluminum foil prepared in the above Example 1 was subjected to mechanical property testing, and its tensile strength was 325 MPa.

[0042] Example 2

[0043] This embodiment provides a method for preparing an ultra-high strength 13 μm battery aluminum foil, comprising the steps of:

[0044] (1) Melting and casting: the alloy elements are prepared according to the following mass percentages: Si 0.24%, Fe 0.44%, Cu 0.19%, Mn 0.86%, Mg 1.19%, Cr 0.02%, Zn 0.04%, Ti 0.015%, and the balance is Al. The raw materials are put into a melting furnace for melting. After the aluminum alloy liquid is completely melted, it is refined to obtain a pure aluminum melt through online SNIF degassing and plate filtration and tubular filtration. The aluminum melt is cast to obtain an aluminum alloy ingot;

[0045] (2) homogenization, placing the aluminum alloy ingot into a heating furnace for homogenization treatment. Specifically, the homogenization process is 615°C*8h, and then cooling to 560°C and directly taking it out of the furnace;

[0046] (3) hot rolling, the aluminum alloy ingot after homogenization is directly subjected to multiple hot rolling to obtain hot rolled plates, and the final rolling temperature is controlled to be ≥330°C; the initial thickness of hot rolling is 596 mm, and after 17 hot rough rolling passes and 4 hot finishing rolling passes, the hot rolled finished product thickness is 2.0 mm, and the state is F state;

[0047] (4) Cold rolling: after the hot-rolled sheet is cooled, multiple cold rolling passes are performed to obtain a cold-rolled product, and the cold-rolled product is annealed after cold rolling; the cold rolling passes are three in total, and the cold-rolled product thickness is 0.22 mm, and the cold-rolled product is annealed, and the cold-rolled product annealing process is 360°C*7h; that is, the cold rolling process is: 2.0 mm / F→three passes to 0.22 mm / H19→0.22 mm / O state;

[0048] (5) Foil rolling: after the annealed cold-rolled product is cooled, multiple passes of foil rolling are performed, and a foil rolling intermediate annealing is performed between the foil rolling passes; the foil rolling specifically includes five passes: the first pass, from 0.22mm to 0.12mm; the second pass, to 65μm; the third pass, to 32μm; the fourth pass, to 19μm; the fifth pass, to 13μm, and after the third pass, foil rolling intermediate annealing is performed, and the foil rolling intermediate annealing process is 300℃*7h; that is, the foil rolling process is: 0.22mm / O state→0.12mm / H14→0.065mm / H18→0.032mm / H19→0.032mm / O state→0.019mm / H14→0.013mm / H14;

[0049] (6) Cutting to obtain battery aluminum foil.

[0050] The battery aluminum foil prepared in the above Example 2 was tested for mechanical properties, and its tensile strength was 322 MPa.

[0051] Example 3

[0052] The difference between Example 3 and Example 2 is that this example adopts a different annealing process to anneal the 13 μm foil rolled product prepared in Example 2 to obtain battery aluminum foil with different mechanical properties to meet the needs of different customers.

[0053] This embodiment adopts the following annealing process for annealing treatment and detects the corresponding tensile strength, specifically:

[0054] When the annealing process is 150℃*1h, the tensile strength is 302MPa;

[0055] When the annealing process is 180℃*1h, the tensile strength is 297MPa;

[0056] When the annealing process is 210℃*1h, the tensile strength is 258MPa;

[0057] When the annealing process is 240℃*1h, the tensile strength is 242MPa;

[0058] When the annealing process is 270℃*1h, the tensile strength is 225MPa;

[0059] When the annealing process is 300℃*1h, the tensile strength is 132MPa;

[0060] When the annealing process is 330℃*1h, the tensile strength is 118MPa.

[0061] It can be seen that by adopting different annealing processes to anneal the 13μm foil rolled products, their mechanical properties can be significantly changed to meet the diversified needs of the market.

[0062] Comparative Example 1

[0063] In this comparative example, 13 μm battery aluminum foil is prepared using 1100 aluminum alloy, and the 1100 aluminum alloy includes the following alloying elements by mass percentage: Si 0.05-0.08%, Fe 0.42-0.48%, Cu 0.07-0.10%, Mn 0.025-0.035%, Mg≤0.01%, Cr≤0.01%, Zn≤0.01%, Ti≤0.015%, and the balance is Al and unavoidable impurity elements, and the total content of impurity elements is ≤0.15%. In this embodiment, the components of 1100 aluminum alloy are specifically: Si 0.06%, Fe 0.45%, Cu0.10%, Mn 0.03%, Mg≤0.01%, Cr≤0.01%, Zn≤0.01%, Ti≤0.015%, and the balance is Al and unavoidable impurity elements.

[0064] In the process of preparing 13 μm battery aluminum foil using the above 1100 aluminum alloy, the homogenization process is the same as that in Example 1, and the hot rolling, cold rolling and foil rolling processes are specifically as follows:

[0065] Hot rolling: The hot rolled finished product has a thickness of 3.2 mm and is in F state;

[0066] Cold rolling: The starting thickness of cold rolling is 3.2mm. After one pass of rolling, cold rolling is annealed. The thickness after one pass is 1.5mm. The annealing process is 360℃*7h. After annealing, three passes of rolling are performed to obtain the cold-rolled finished product. The thickness of the cold-rolled finished product is 0.22mm and H18 state.

[0067] Foil rolling: There are 5 passes in total, namely 0.22~0.1mm→40μm→20μm→13μm.

[0068] The battery aluminum foil prepared in the above comparative example 1 was subjected to mechanical property testing, and its tensile strength was 218 MPa.

[0069] The mechanical properties of the battery aluminum foil of the above-mentioned Example 1 and Comparative Example 1 are compared. The tensile strength of the battery aluminum foil of the present Example 1 can reach more than 320 MPa, while that of Comparative Example 1 is only 218 MPa. The battery aluminum foil of the present Example 1 has ultra-high strength and is suitable for batteries with high requirements on strength.

[0070] It should be noted that some parts not described in the present invention can be realized by adopting or drawing on existing technologies, such as smelting processes, casting processes, etc., which are realized using existing technologies.

[0071] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An ultra-high strength 13μm battery aluminum foil, characterized in that: The alloy elements include the following mass percentages: Si 0.23-0.27%, Fe 0.44-0.50%, Cu 0.185-0.205%, Mn 0.86-0.90%, Mg 1.19-1.24%, Cr≤0.04%, Zn≤0.06%, Ti 0.01-0.025%, and the balance is Al and unavoidable impurity elements, and the total content of impurity elements is ≤0.15%.

2. The method for preparing an ultra-high strength 13 μm battery aluminum foil according to claim 1, characterized in that: Includes steps: (1) Melting and casting: weighing corresponding raw materials according to alloy components and proportions, and putting them into a melting furnace for melting. After the aluminum alloy liquid is completely melted, refining is performed, and pure aluminum melt is obtained by online SNIF degassing and online filtration. The aluminum melt is cast to obtain an aluminum alloy ingot; (2) homogenization, placing the aluminum alloy ingot into a heating furnace for homogenization treatment; (3) hot rolling, wherein the homogenized aluminum alloy ingot is subjected to multiple hot rolling passes to obtain a hot rolled coil, and the final rolling temperature is controlled to be ≥330°C; (4) cold rolling, after the hot rolled coil is cooled, performing multiple cold rolling passes to obtain a cold rolled product, and annealing the cold rolled product after cold rolling; (5) foil rolling, after the annealed cold-rolled product is cooled, multiple passes of foil rolling are performed, and an intermediate foil rolling annealing is performed between the foil rolling passes; (6) Cutting to obtain battery aluminum foil.

3. The method for preparing an ultra-high strength 13 μm battery aluminum foil according to claim 1, characterized in that: The homogenization process in step (2) is 605±10°C*5~10h+550±10°C*0~4h.

4. The method for preparing an ultra-high strength 13 μm battery aluminum foil according to claim 1, characterized in that: The thickness of the hot-rolled coil in step (3) is 2.0 to 2.1 mm.

5. The method for preparing an ultra-high strength 13 μm battery aluminum foil according to claim 1, characterized in that: In the step (4), there are three cold rolling passes in total, and the thickness of the cold rolled product is 0.21 to 0.25 mm.

6. The method for preparing an ultra-high strength 13 μm battery aluminum foil according to claim 1, characterized in that: The cold-rolled finished product annealing process in step (4) is 360±10°C*6-8h.

7. The method for preparing an ultra-high strength 13 μm battery aluminum foil according to claim 1, characterized in that: The foil rolling in step (5) includes: the first pass, pressing from 0.21-0.25 mm to 0.12 mm; the second pass, pressing to 65 μm; the third pass, pressing to 32 μm; the fourth pass, pressing to 19 μm; and the fifth pass, pressing to 13 μm.

8. The method for preparing an ultra-high strength 13 μm battery aluminum foil according to claim 7, characterized in that: In the step (5), foil rolling intermediate annealing is performed after the third pass, and the foil rolling intermediate annealing process is 300±10°C*6~8h.