Preparation process of 8021 aluminum foil for super-wide lithium battery

Abstract

The application discloses a preparation process of 8021 aluminum foil for ultra-wide lithium battery, comprising the following steps: S1, smelting; S2, casting and rolling; S3, homogenizing annealing; S4, cold rolling; S5, finished product annealing. By increasing the casting nozzle chamfer angle, adjusting the roll diameter, grinding the convexity and the length of the casting and rolling area, the application effectively reduces the risk of fracture caused by liquid aluminum impact. At the same time, through the homogenizing annealing and cold rolling process, by using precise temperature and time control, as well as the adjustment of rolling oil flow and cooling temperature, the plasticity and ductility of the aluminum foil are further improved, and the fracture caused by excessive stress in the calendering process is avoided. Finally, through the precise finished product annealing process, the stress relief annealing of the finished aluminum coil is realized, the internal stress is eliminated, and the possibility of fracture is further reduced. This preparation process not only improves the production efficiency and product quality of the aluminum foil, reduces the production cost, and improves the market competitiveness of the product.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy preparation, and more specifically to a preparation process for 8021 aluminum foil for ultra-wide lithium batteries. Background Technology

[0002] Lithium-ion batteries are increasingly used in various devices, including mobile devices, electric vehicles, and energy storage systems. In the manufacturing process of lithium-ion batteries, 8021 aluminum foil is widely used as the positive electrode current collector due to its excellent electrical conductivity and charge transfer capabilities.

[0003] However, with the development of electric vehicles and large-scale energy storage systems, the demand for larger battery sizes is also increasing. This necessitates wider aluminum foil to meet the manufacturing requirements of larger batteries. Ultra-wide 8021 aluminum foil, due to its greater width, can provide a larger surface area, thereby improving the energy density and power density of the battery.

[0004] However, existing manufacturing processes for ultra-wide 8021 aluminum foil have some problems. During production, due to the characteristics of the aluminum foil material and limitations of production equipment, ultra-wide aluminum foil is prone to breakage. This not only affects production efficiency but also increases production costs. Therefore, how to solve the breakage problem of ultra-wide 8021 aluminum foil during production and improve its production efficiency and quality is a crucial issue currently facing the lithium battery manufacturing industry.

[0005] Furthermore, the breakage issue of ultra-wide 8021 aluminum foil can also affect the quality of the final product. If the aluminum foil breaks during production, it may result in incomplete current collectors in the battery, affecting battery performance and reliability. Therefore, solving the breakage problem of ultra-wide 8021 aluminum foil can not only improve production efficiency but also enhance the performance and reliability of lithium batteries.

[0006] Therefore, the drawback of the existing technology is that the ultra-wide 8021 aluminum foil is prone to breakage during the production process, which affects production efficiency and product quality. Summary of the Invention

[0007] To address the problem of breakage during the production of ultra-wide 8021 aluminum foil in existing technologies, a preparation process for ultra-wide 8021 aluminum foil for lithium batteries is provided, the specific scheme of which is as follows:

[0008] A process for preparing 8021 aluminum foil for ultra-wide lithium batteries includes the following steps:

[0009] S1. Smelting: According to the alloy material ratio, aluminum ingots are added. After the raw materials are melted, aluminum-silicon master alloy and aluminum-iron master alloy are added to adjust the composition. After the raw materials are smelted, they are introduced into a settling furnace.

[0010] S2, Casting and Rolling: The treated aluminum liquid is cast and rolled, the chamfer angle of the casting nozzle is increased, and the roll diameter, grinding crown and length of the casting and rolling zone are adjusted.

[0011] S3. Homogenization Annealing: The produced cast-rolled coils are first homogenized, then annealed and cooled to room temperature.

[0012] S4. Cold rolling: The homogenized aluminum coil is cold rolled and then trimmed. It is then cold rolled to the finished thickness. Rolling oil is used for cooling during the cold rolling process.

[0013] S5. Finished product annealing: Stress-relief annealing is performed on the finished aluminum coil to achieve the required mechanical properties.

[0014] Furthermore, the chamfer angle of the casting nozzle in S2 is increased by 50-70%.

[0015] Furthermore, the ratio of the roll diameter to the width of the 8021 aluminum foil blank is set to 1:(1.75~2.3); the grinding crown is 0.28 / 0.28mm.

[0016] Furthermore, the length of the casting and rolling zone is set to 56–60 mm.

[0017] Furthermore, the alloy composition in S1 is Fe = 1.5–2.0%, Si < 0.25%, Cu < 0.15%, Mn < 0.1%, Mg < 0.05%, Cr < 0.05%, Zn < 0.05%, Ti < 0.05%, with the remainder being Al.

[0018] Furthermore, the S3 homogenization annealing includes the following steps:

[0019] Preheating stage: Place the cast coil into the heat treatment furnace, set the furnace temperature between 280℃ and 320℃, and maintain this temperature for about 2-4 hours to allow the temperature inside the aluminum foil to gradually rise and be evenly distributed.

[0020] Heating stage: Gradually increase the furnace temperature to 450℃-500℃, and control the heating rate at 100℃ / h to prevent the aluminum foil from developing stress and deformation due to excessive heating.

[0021] Heat preservation stage: After reaching 450℃-500℃, maintain this temperature for about 4-6 hours to allow the chemical composition and microstructure inside the aluminum foil to become uniform.

[0022] Cooling stage: After the heat preservation is completed, the furnace temperature is gradually reduced to room temperature, and the cooling rate is controlled at 50℃ / h to prevent the aluminum foil from generating stress and deformation due to excessive cooling.

[0023] Furthermore, S4 cold rolling includes the following steps:

[0024] Preparation stage: First, put the homogenized aluminum coil into the cold rolling mill, set the flow rate and cooling temperature of the rolling oil, with the flow rate at 20-30L / min and the cooling temperature controlled at 10-15℃ to ensure the temperature stability of the aluminum coil during the rolling process.

[0025] Rolling stage: The aluminum coil is rolled in a cold rolling mill. The rolling pressure is controlled at 200-300MPa and the rolling speed is controlled at 1000-1500mm / min to ensure that the thickness of the aluminum coil is uniform.

[0026] Edge trimming stage: The rolled aluminum coil is trimmed. The cutting speed of the trimming machine is controlled at 500-1000 mm / min, and the cutting depth is controlled at 0.1-0.2 mm to ensure that the edges of the aluminum coil are flat.

[0027] Cold rolling to finished thickness: The aluminum coil after edge trimming continues to be cold rolled, with the rolling pressure controlled at 300-400MPa, the rolling speed controlled at <380m / min, and the flow rate of rolling oil and cooling temperature maintained at the settings of the preparatory stage, until the aluminum coil thickness reaches the finished product requirements.

[0028] Furthermore, the S5 finished product annealing includes the following steps:

[0029] Preheating stage: Place the finished aluminum coil into the annealing furnace, set the furnace temperature between 200℃ and 250℃, and maintain this temperature for about 2-3 hours to allow the temperature inside the aluminum coil to gradually rise and be evenly distributed.

[0030] Heating stage: Gradually increase the furnace temperature to 350℃-400℃, and control the heating rate at 50℃ / h to prevent the aluminum coil from developing stress and deformation due to excessive heating.

[0031] Insulation stage: After reaching 350℃-400℃, maintain this temperature for about 4-6 hours to allow the chemical composition and microstructure inside the aluminum coil to become uniform.

[0032] Cooling stage: After the heat preservation is completed, the furnace temperature is gradually reduced to room temperature, and the cooling rate is controlled at 50℃ / h to prevent the aluminum coil from generating stress and deformation due to excessive cooling.

[0033] Beneficial effects:

[0034] This invention provides a process for preparing 8021 aluminum foil for ultra-wide lithium batteries, which has the following advantages:

[0035] (1) By increasing the chamfer angle of the casting nozzle during the casting and rolling process, the flow of molten aluminum is made smoother, reducing the risk of breakage caused by impact. Secondly, by reasonably adjusting the roll diameter, the width and thickness of the aluminum foil can be better controlled to meet the requirements of ultra-wide lithium batteries. This roll diameter can also effectively reduce the stress on the aluminum foil during the rolling process, avoiding breakage. In addition, by adjusting the grinding crown, the surface of the aluminum foil can be made smoother, thereby improving the surface quality of the aluminum foil and reducing the risk of breakage in subsequent processing. Finally, by adjusting the length of the casting and rolling zone, we ensure that the molten aluminum is sufficiently cooled during the casting and rolling process, avoiding breakage caused by insufficient cooling.

[0036] (2) Through homogenization annealing and cold rolling processes, precise temperature and time control, as well as adjustments to the flow rate of rolling oil and cooling temperature, further improved the plasticity and ductility of the aluminum foil, avoiding breakage caused by excessive stress during the rolling process. Finally, through a precise finished product annealing process, stress-relief annealing of the finished aluminum coil was achieved, eliminating internal stress and further reducing the possibility of breakage. The above operations not only effectively improved the production efficiency and product quality of aluminum foil, reduced production costs, and enhanced the market competitiveness of the products, but also achieved refined management of the aluminum foil production process through precise parameter control and operation, thereby ensuring the stability and consistency of aluminum foil products and meeting the high standard requirements of ultra-wide-width lithium batteries. Detailed Implementation

[0037] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0038] Example 1:

[0039] S1. Smelting: Aluminum ingots are added according to the alloy composition of Fe=1.7%, Si<0.25%, Cu<0.15%, Mn<0.1%, Mg<0.05%, Cr<0.05%, Zn<0.05%, Ti<0.05%, with the remainder being Al. After the raw materials are melted, aluminum-silicon master alloy and aluminum-iron master alloy are added to adjust the composition; after smelting, the raw materials are introduced into a settling furnace.

[0040] S2. Casting and rolling: The treated molten aluminum is cast and rolled. The chamfer angle of the casting nozzle is set to 45°, the ratio of the roll diameter to the width of the 8021 aluminum foil blank is set to 1:2, the grinding crown is 0.28 / 0.28mm, and the length of the casting and rolling zone is set to 58mm.

[0041] S3. Homogenization Annealing: The produced cast-rolled coils are first homogenized. The coils are then placed in a heat treatment furnace, with the furnace temperature preset at 300℃ and maintained at this temperature for approximately 3 hours. The furnace temperature is then gradually increased to 470℃, with a heating rate controlled at 100℃ / h. After reaching 470℃, this temperature is maintained for approximately 5 hours. After holding at this temperature, the furnace temperature is gradually reduced to room temperature, with a cooling rate controlled at 50℃ / h. The coils are then cooled to room temperature after annealing.

[0042] S4. Cold Rolling: The homogenized aluminum coil is cold rolled, with the rolling oil flow rate set at 25 L / min and the cooling temperature controlled at 12℃. The aluminum coil is rolled in a cold rolling mill with a rolling pressure controlled at 250 MPa and a rolling speed controlled at 1250 mm / min. The rolled aluminum coil is then trimmed, with the trimming speed controlled at 750 mm / min and the cutting depth controlled at 0.15 mm. The trimmed aluminum coil continues to be cold rolled, with the rolling pressure controlled at 350 MPa and the rolling speed controlled at 350 m / min, until the aluminum coil thickness meets the finished product requirements.

[0043] S5. Finished product annealing: Stress-relief annealing is performed on the finished thickness aluminum coil. The finished thickness aluminum coil is placed in the annealing furnace, and the furnace temperature is preset at 225℃ and maintained at this temperature for about 2.5 hours. The furnace temperature is gradually increased to 375℃, and the heating rate is controlled at 50℃ / h. After reaching 375℃, this temperature is maintained for about 5 hours. After the heat preservation is completed, the furnace temperature is gradually reduced to room temperature, and the cooling rate is controlled at 50℃ / h.

[0044] Example 2:

[0045] S1. Smelting: Aluminum ingots are added according to the alloy composition of Fe=1.7%, Si<0.25%, Cu<0.15%, Mn<0.1%, Mg<0.05%, Cr<0.05%, Zn<0.05%, Ti<0.05%, with the remainder being Al. After the raw materials are melted, aluminum-silicon master alloy and aluminum-iron master alloy are added to adjust the composition; after smelting, the raw materials are introduced into a settling furnace.

[0046] S2, Casting and Rolling: The treated molten aluminum is cast and rolled. The chamfer angle of the casting nozzle is set to 50°, the ratio of the roll diameter to the width of the 8021 aluminum foil blank is set to 1:2, the grinding crown is 0.28 / 0.28mm, and the length of the casting and rolling zone is set to 58mm.

[0047] S3. Homogenization Annealing: The produced cast-rolled coils are first homogenized. The coils are then placed in a heat treatment furnace, with the furnace temperature preset at 300℃ and maintained at this temperature for approximately 3 hours. The furnace temperature is then gradually increased to 470℃, with a heating rate controlled at 100℃ / h. After reaching 470℃, this temperature is maintained for approximately 5 hours. After holding at this temperature, the furnace temperature is gradually reduced to room temperature, with a cooling rate controlled at 50℃ / h. The coils are then cooled to room temperature after annealing.

[0048] S4. Cold Rolling: The homogenized aluminum coil is cold rolled, with the rolling oil flow rate set at 25 L / min and the cooling temperature controlled at 12℃. The aluminum coil is rolled in a cold rolling mill with a rolling pressure controlled at 250 MPa and a rolling speed controlled at 1250 mm / min. The rolled aluminum coil is then trimmed, with the trimming speed controlled at 750 mm / min and the cutting depth controlled at 0.15 mm. The trimmed aluminum coil continues to be cold rolled, with the rolling pressure controlled at 350 MPa and the rolling speed controlled at 360 m / min, until the aluminum coil thickness meets the finished product requirements.

[0049] S5. Finished product annealing: Stress-relief annealing is performed on the finished thickness aluminum coil. The finished thickness aluminum coil is placed in the annealing furnace, and the furnace temperature is preset at 225℃ and maintained at this temperature for about 2.5 hours. The furnace temperature is gradually increased to 375℃, and the heating rate is controlled at 50℃ / h. After reaching 375℃, this temperature is maintained for about 5 hours. After the heat preservation is completed, the furnace temperature is gradually reduced to room temperature, and the cooling rate is controlled at 50℃ / h.

[0050] Example 3:

[0051] S1. Smelting: Aluminum ingots are added according to the alloy composition of Fe=1.7%, Si<0.25%, Cu<0.15%, Mn<0.1%, Mg<0.05%, Cr<0.05%, Zn<0.05%, Ti<0.05%, with the remainder being Al. After the raw materials are melted, aluminum-silicon master alloy and aluminum-iron master alloy are added to adjust the composition; after smelting, the raw materials are introduced into a settling furnace.

[0052] S2. Casting and rolling: The treated molten aluminum is cast and rolled. The chamfer angle of the casting nozzle is set to 45°, the ratio of the roll diameter to the width of the 8021 aluminum foil blank is set to 1:2, the grinding crown is 0.28 / 0.28mm, and the length of the casting and rolling zone is set to 58mm.

[0053] S3. Homogenization Annealing: The produced cast-rolled coils are first homogenized. The coils are then placed in a heat treatment furnace, with the furnace temperature preset at 300℃ and maintained at this temperature for approximately 3 hours. The furnace temperature is then gradually increased to 470℃, with a heating rate controlled at 100℃ / h. After reaching 470℃, this temperature is maintained for approximately 5 hours. After holding at this temperature, the furnace temperature is gradually reduced to room temperature, with a cooling rate controlled at 50℃ / h. The coils are then cooled to room temperature after annealing.

[0054] S4. Cold Rolling: The homogenized aluminum coil is cold rolled, with the rolling oil flow rate set at 30 L / min and the cooling temperature controlled at 15℃. The aluminum coil is rolled in a cold rolling mill with a rolling pressure controlled at 300 MPa and a rolling speed controlled at 1500 mm / min. The rolled aluminum coil is then trimmed, with the trimming speed controlled at 1000 mm / min and the cutting depth controlled at 0.2 mm. The trimmed aluminum coil continues to be cold rolled, with the rolling pressure controlled at 400 MPa and the rolling speed controlled at 360 m / min, until the aluminum coil thickness meets the finished product requirements.

[0055] S5. Finished product annealing: Stress-relief annealing is performed on the finished thickness aluminum coil. The finished thickness aluminum coil is placed in the annealing furnace, and the furnace temperature is preset at 225℃ and maintained at this temperature for about 2.5 hours. The furnace temperature is gradually increased to 375℃, and the heating rate is controlled at 50℃ / h. After reaching 375℃, this temperature is maintained for about 5 hours. After the heat preservation is completed, the furnace temperature is gradually reduced to room temperature, and the cooling rate is controlled at 50℃ / h.

[0056] Comparative example:

[0057] Ultra-wide 8021 aluminum foil produced using conventional methods.

[0058] The breakage rate of the ultra-wide 8021 aluminum foil produced in Examples 1-3 and the comparative example was tested, and the test data are as follows:

[0059] Fracture rate 1.8％ 1.5％ 1.2％ 2.5％

[0060] The data above shows that the breakage rate of ultra-wide 8021 aluminum foil produced using this technical solution is lower than that of aluminum foil produced using conventional methods. This indicates that this technical solution has a significant advantage in preventing aluminum foil breakage.

[0061] As a further improvement, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for preparing 8021 aluminum foil for ultra-wide lithium batteries, characterized in that, Includes the following steps: S1. Smelting: According to the alloy material ratio, aluminum ingots are added. After the raw materials are melted, aluminum-silicon master alloy and aluminum-iron master alloy are added to adjust the composition. After the raw materials are smelted, they are introduced into a settling furnace. S2, Casting and Rolling: The treated aluminum liquid is cast and rolled, the chamfer angle of the casting nozzle is increased, and the roll diameter, grinding crown and length of the casting and rolling zone are adjusted. S3. Homogenization Annealing: The produced cast-rolled coils are first homogenized, then annealed and cooled to room temperature. S4. Cold rolling: The homogenized aluminum coil is cold rolled and then trimmed. It is then cold rolled to the finished thickness. Rolling oil is used for cooling during the cold rolling process. S5. Finished product annealing: Stress-relief annealing is performed on the finished aluminum coil to achieve the required mechanical properties. The homogenization annealing steps in S3 include: placing the cast-rolled coil into a heat treatment furnace, setting the furnace temperature between 280℃ and 320℃, and maintaining this temperature for 2 to 4 hours; gradually increasing the furnace temperature to 450℃ to 500℃, with the heating rate controlled at 100℃ / h; maintaining this temperature for 4 to 6 hours after reaching 450℃ to 500℃; and gradually reducing the furnace temperature to room temperature after the heat treatment is completed, with the cooling rate controlled at 50℃ / h. S4 cold rolling includes the following steps: First, the homogenized aluminum coil is placed into a cold rolling mill. The flow rate and cooling temperature of the rolling oil are set to 20-30 L / min and 10-15℃. The aluminum coil is then rolled in the cold rolling mill. The rolling pressure is controlled at 200-300 MPa and the rolling speed is controlled at 1000-1500 mm / min. The rolled aluminum coil is then trimmed. The trimming speed of the trimming machine is controlled at 500-1000 mm / min and the cutting depth is controlled at 0.1-0.2 mm. The trimmed aluminum coil is then further cold rolled. The rolling pressure is controlled at 300-400 MPa and the rolling speed is controlled at <380 m / min. The flow rate and cooling temperature of the rolling oil are maintained at the settings of the preparatory stage until the thickness of the aluminum coil reaches the required finished product thickness. The S5 finished product annealing includes the following steps: Place the finished aluminum coil into the annealing furnace, preset the furnace temperature between 200℃ and 250℃, and maintain this temperature for 2-3 hours; gradually increase the furnace temperature to 350℃-400℃, with the heating rate controlled at 50℃ / h; after reaching 350℃-400℃, maintain this temperature for 4-6 hours; after the heat preservation is completed, gradually reduce the furnace temperature to room temperature, with the cooling rate controlled at 50℃ / h.

2. The preparation process of 8021 aluminum foil for ultra-wide lithium batteries according to claim 1, characterized in that, The chamfer angle of the casting nozzle in S2 increases by 50-70%.

3. The preparation process of 8021 aluminum foil for ultra-wide lithium batteries according to claim 1, characterized in that, The ratio of the roll diameter to the width of the 8021 aluminum foil blank is set to 1:(1.75~2.3); the grinding crown is 0.28 / 0.28mm.

4. The preparation process of 8021 aluminum foil for ultra-wide lithium batteries according to claim 1, characterized in that, The length of the casting and rolling zone is set to 56~60mm.

5. The preparation process of 8021 aluminum foil for ultra-wide lithium batteries according to claim 1, characterized in that, The alloy composition of S1 is Fe = 1.5-2.0%, Si < 0.25%, Cu < 0.15%, Mn < 0.1%, Mg < 0.05%, Cr < 0.05%, Zn < 0.05%, Ti < 0.05%, and the remainder is Al.