Processing method for improving performance of battery soft package aluminum foil and high-deep-drawing battery soft package aluminum foil

Abstract

The invention provides a processing method for improving the performance of a battery soft package aluminum foil and a high-deep-drawing battery soft package foil. According to the method, a process route of a cold rolling process 1-an intermediate heat treatment annealing process-a cold rolling process 2-foil rolling and slitting-a finished product heat treatment annealing process is adopted, and the high-deep-drawing battery flexible package foil is prepared. According to the processing method, by changing the cold rolling process and the heat treatment process of the battery soft package aluminum foil blank, the performance of the blank is improved, and the blank energy storage is increased; after foil rolling, rolling and slitting, recrystallization annealing is carried out on a battery soft package finished product aluminum foil at a relatively low temperature, so that the dispersion strengthening of crystal grains is improved, the uniform and fine size of the crystal grains is promoted, and the deep drawing performance of the finished product aluminum foil is improved. And meanwhile, the aluminum foil roll cannot be adhered when being unfolded through a lower-temperature heat treatment process, so that the use performance of the aluminum foil is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of battery soft package aluminum foil processing, and particularly relates to a processing method for improving the performance of battery soft package aluminum foil and a high-deep-drawing battery soft package foil. Background Art

[0002] Aluminum foil is used in lithium battery flexible packaging aluminum-plastic film due to its excellent barrier properties (water and oxygen isolation). It is one of the core key materials, and imported aluminum foil was mostly used before.

[0003] Aluminum foil, as the middle material, will cause the cupping of aluminum-plastic film to be too low. At present, the deep-drawing cupping of domestic aluminum-plastic film is generally 7.0~7.5mm, which cannot meet the high deep-drawing capacity, affecting the capacity density of soft-pack batteries. At the same time, the shell breakage rate of downstream customers is too high. Under the high-temperature (about 280°C) annealing process conditions of the finished product, the aluminum foil of the battery soft pack is prone to adhesion, which is easy to cause poor plate shape and leak coating during the processing and manufacturing process of the aluminum-plastic film enterprise, thus affecting the sealing performance of the aluminum-plastic film.

[0004] Therefore, it is urgent to provide a processing method for improving the performance of battery soft-pack aluminum foil. Summary of the invention

[0005] Based on the defects of the prior art, the first purpose of the present invention is to provide a processing method for improving the performance of battery soft-pack aluminum foil; this method adopts a cold rolling process 1-intermediate heat treatment annealing process-cold rolling process 2-foil rolling and slitting-finished product heat treatment annealing process route, which expands the existing battery soft-pack aluminum foil process route, and can produce aluminum foil with higher deep drawing performance, increasing the demand for unit volume energy density of soft-pack batteries; the second purpose of the present invention is to provide a high-deep drawing battery soft packaging foil prepared by the processing method.

[0006] The purpose of the present invention is achieved through the following technical solutions: In one aspect, the present invention provides a processing method for improving the performance of battery soft pack aluminum foil, which comprises the following steps: (1) Cold rolling process 1: The 8021 alloy hot-rolled coil that meets the standard rolling conditions is cold rolled to a thickness between 0.9 mm and 1.0 mm by reducing one rolling pass; (2) Intermediate heat treatment annealing process: The coil after cold rolling process 1 is subjected to intermediate annealing to obtain a blank to optimize the grain and microstructure; (3) Cold rolling process 2: After annealing, the billet is subjected to an additional rolling pass for cold rolling to a final thickness of 0.26 mm to 0.30 mm. (4) Foil rolling and slitting: rolling and slitting the cold rolled coil into aluminum foil to obtain the finished product; (5) Finished product heat treatment annealing process: The finished product after aluminum foil rolling and slitting is subjected to low-temperature heat treatment annealing to obtain high-deep-drawing battery soft packaging foil.

[0007] In the above processing method, preferably, in step (1), the target thickness of the cold rolling reduction by one rolling pass is adjusted according to the width to: (a) For coils with a width of 1710 mm and above, a target thickness of 4.0 mm - 2.0 mm - 1.0 mm is used; (b) For coils with a width less than 1710 mm, a target thickness of 4.0 mm - 1.8 mm - 0.9 mm is used.

[0008] In the above processing method, preferably, before step (1), the method includes testing the performance of the hot-rolled finished product to verify the quality of the hot-rolled coil.

[0009] In the above processing method, preferably, in step (2), the intermediate heat treatment annealing process is set to a temperature range of 400-440° C., and the continuous annealing time is 4-12 hours.

[0010] In the above processing method, preferably, before performing step (3), the blank needs to be cooled to below 100°C.

[0011] In the above processing method, preferably, in step (3), the target thickness of cold rolling reduction in one rolling pass is adjusted according to the width to: A target thickness of 0.9 mm-0.46 mm-0.26 mm was adopted; and a target thickness of 1.0 mm-0.52 mm-0.30 mm was adopted.

[0012] In the above processing method, preferably, in step (3), after the cold rolling process 2, the tensile strength of the blank is significantly improved and the uniformity of the material thickness is optimized, and the tensile strength of the blank is improved by at least 170 MPa.

[0013] In the above processing method, preferably, in step (4), during the foil rolling and slitting process, the foil rolling thickness changes as follows: 0.26 mm-0.13 mm-0.08 mm-0.04 mm and 0.30 mm-0.15 mm-0.09 mm-0.055 mm.

[0014] In the above processing method, preferably, in step (5), the finished product heat treatment annealing process is set to a temperature range of 200-240°C.

[0015] In the above processing method, preferably, in step (5), a low temperature heat treatment annealing treatment is performed to promote the formation of fine and uniform recrystallized grains, significantly improve the deep drawing performance of the aluminum foil and improve the adhesion between aluminum foils, the deep drawing performance of the aluminum foil is improved by 10% to 15%, the battery electrolyte filling volume is increased by 10% to 20%, and the energy density is increased by 8% to 10%. After annealing, the cupping performance of 40um, 45um, and 55um thicknesses can achieve performance greater than 8.0mm, 8.3mm, and 8.5mm.

[0016] On the other hand, the present invention also provides a high-deep-drawing battery soft packaging foil, which is prepared by the above processing method.

[0017] Beneficial effects of the present invention: The processing method for improving the performance of battery soft-package aluminum foil of the present invention is to formulate a new process method for the rolling process of the blank, the heat treatment process control and the finished product heat treatment process, which can significantly improve the deep drawing performance (cupping value) of the aluminum foil and the unfolding performance of the aluminum foil roll. It not only improves the punching depth of a single soft-package battery shell and improves the energy density; it can also improve the yield rate of aluminum-plastic film manufacturing enterprises.

[0018] Specifically, the present invention adopts different cold rolling processes and intermediate heat treatment processes to improve the strength of the blank and increase the intrinsic energy storage of the raw materials; the aluminum foil after foil rolling undergoes low-temperature recrystallization annealing to improve the dispersion strengthening of the grains and promote the uniform and fine grain size, increase the number of grains, ensure the fine size of the grains, and improve the deep drawing performance of the finished aluminum foil. The deep drawing performance of the battery soft package aluminum foil is improved from 7.0mm to 8.0mm, and the thickness of 50um can be more than 8.5mm. The battery electrolyte filling volume is increased by 10%~20%, and the energy density is increased by 8%~10%. After the aluminum foil is annealed, the aluminum coil will not stick together, which improves the performance of the aluminum foil and the product qualification rate is increased by 10%~15%.

[0019] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1To improve the tensile strength mechanical properties of the front soft-pack battery blank in Example 1.

[0022] Figure 2 The cupping performance of the soft-pack battery prepared from the soft-pack battery blank before improvement in Example 1.

[0023] Figure 3 It is the tensile strength of the soft-pack battery blank after the processing method of Example 1 of the present invention.

[0024] Figure 4 The cupping performance of the soft-pack battery prepared from the high-deep-drawing soft-pack battery foil obtained by the processing method of Example 1 of the present invention. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The process, conditions, reagents, experimental methods, etc. for implementing the present invention, except for the contents specifically mentioned below, are all common knowledge and common common sense in the art, and the present invention does not particularly limit the contents.

[0026] Embodiment 1: This embodiment provides a processing method for improving the performance of battery soft package aluminum foil and the high-deep-drawing battery soft package foil prepared therefrom, the method comprising the following steps: (1) Cold rolling process 1: The 8021 alloy hot-rolled coil that meets the standard rolling conditions is subjected to performance testing to verify the quality of the hot-rolled coil, and then the hot-rolled coil is cold-rolled to a thickness of between 0.9 mm and 1.0 mm by reducing one rolling pass; specifically: (a) For coils with a width of 1710 mm and above, a target thickness of 4.0 mm - 2.0 mm - 1.0 mm is used; (b) For coils with a width less than 1710 mm, a target thickness of 4.0 mm - 1.8 mm - 0.9 mm is used.

[0027] (2) Intermediate heat treatment annealing process: The coil after the cold rolling process 1 is subjected to intermediate annealing treatment at a temperature of 400-440°C for a continuous annealing time of 4-12 hours to obtain a billet in order to optimize the grain and microstructure.

[0028] (3) Cold rolling process 2: After annealing, the billet is subjected to an additional rolling pass for cold rolling to a final thickness of 0.26 mm to 0.30 mm. Specifically: For (b) a reduction target thickness of 0.9 mm-0.46 mm-0.26 mm is adopted; and, For (a), a reduction target thickness of 1.0 mm-0.52 mm-0.30 mm was used; By adopting this step, the tensile strength of the billet increases by about 20%, and the tensile strength is increased from 140~150MPa to about 170Mpa. The thickness of the billet is increased, and the deformation of the billet is increased by 100%. The metal grains are more broken, the metal structure texture is longer, and the energy storage is increased, which provides more sufficient kinetic energy for subsequent recrystallization annealing.

[0029] (4) Foil rolling and slitting: Aluminum foil is rolled and slitting is performed on the cold rolled coil. The thickness of the foil rolling changes as follows: For (b) 0.26 mm-0.13 mm-0.08 mm-0.04 mm and For (a) 0.30 mm-0.15 mm-0.09 mm-0.055 mm; the finished product is obtained; after being rolled again through aluminum foil, more energy is stored.

[0030] (5) Finished product heat treatment annealing process: The finished product after aluminum foil rolling and slitting is subjected to low-temperature heat treatment annealing at a temperature of 200-240°C to obtain a high-deep-drawing battery soft packaging foil (45um thickness, cup protrusion>8.3mm); By adopting this step, at the annealing temperature of 200~240℃, the recrystallization temperature begins to decrease, and in a low temperature environment, the newly added grains become small and uniform, so that after annealing, the deep drawing performance of the aluminum foil is significantly improved, about 10%~15% compared with before; at the same time, under low temperature conditions, the mutual adhesion between the aluminum foils is greatly improved.

[0031] Regardless of the coil of a or b, a cold rolling pass can be performed before 4.0 mm with a target thickness of 7-4.0 mm. In this case, the number of rolling passes of cold rolling process 1 is 3. The number of rolling passes of cold rolling process 2 is 2.

[0032] The processing method of the present invention improves the deep-drawing performance of the finished aluminum foil, and the deep-drawing performance of the battery soft-pack aluminum foil is improved from 7.0mm to 8.0mm, and the thickness of 50um can be above 8.5mm. The battery electrolyte filling volume is increased by 10% to 20%, and the energy density is increased by 8% to 10%. After the aluminum foil is annealed, the aluminum coil will not stick together, which improves the performance of the aluminum foil and increases the product qualification rate by 10% to 15%.

[0033] The specific experimental data are as follows: From January 2022 to September 2024, 12 batches of coils were tested using the processing method of Example 1 of the present invention.

[0034] Improve the tensile strength and mechanical properties of the front soft pack battery blank such as Figure 1 As shown in the figure, the cupping performance of the soft pack battery prepared from the soft pack battery blank before improvement is as follows Figure 2 shown.

[0035] Depend on Figure 1 It can be seen that the tensile strength of the blank is low, between 150 and 160 MPa.

[0036] Depend on Figure 2 It can be seen that the cupping value of the soft-pack battery before improvement was relatively low, between 7.2 and 8.0 mm.

[0037] The tensile strength of the soft pack battery blank after the processing method of Example 1 of the present invention is as follows: Figure 3 As shown in the figure, the cupping performance of the soft pack battery prepared by the high deep drawing soft pack battery foil obtained by this processing method is as follows Figure 4 shown.

[0038] Depend on Figure 3 It can be seen that the tensile strength of the blank is increased by 10~15MPa.

[0039] Depend on Figure 4 It can be seen that the cupping value of the soft-pack battery is increased by 0.5~1.0mm.

[0040] By adjusting the cold rolling process and heat treatment annealing process of the billet, and the heat treatment annealing process of the soft-pack battery finished product, the tensile strength of the soft-pack battery billet has been significantly improved, the cupping value of the soft-pack battery has been significantly improved, and the deep drawing performance of the soft-pack battery has been significantly improved. Through improvements, the deep drawing performance of the soft-pack battery has been improved, the probability of shell breakage for downstream customers has been reduced, and customer satisfaction has increased by 5%.

[0041] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A processing method for improving the performance of battery soft pack aluminum foil, characterized in that: It includes the following steps: (1) Cold rolling process 1: cold rolling the 8021 alloy hot-rolled coil that meets the standard rolling conditions to a thickness between 0.9 mm and 1.0 mm; Among them, the target thickness of cold rolling is adjusted according to the width: (a) For coils with a width of 1710 mm and above, two rolling passes of 4.0 mm-2.0 mm-1.0 mm are used to reduce the target thickness; (b) For coils with a width less than 1710 mm, two rolling passes of 4.0 mm-1.8 mm-0.9 mm are used to reduce the target thickness; (2) Intermediate heat treatment annealing process: The coil after cold rolling process 1 is subjected to intermediate annealing to obtain a blank to optimize the grain and microstructure; (3) Cold rolling process 2: The billet is cooled to below 100°C. After annealing, the billet is cold rolled in two passes to obtain a cold rolled coil with a final thickness of 0.26 mm to 0.30 mm. Among them, the target thickness of cold rolling is adjusted according to the width: For (b), a reduction target thickness of 0.9 mm-0.46 mm-0.26 mm is adopted; and, For (a), a reduction target thickness of 1.0 mm-0.52 mm-0.30 mm was adopted; After cold rolling process 2, the tensile strength of the billet is significantly improved and the thickness uniformity of the material is optimized. The tensile strength of the billet is increased by at least 170MPa. (4) Foil rolling and slitting: rolling and slitting the cold rolled coil into aluminum foil to obtain the finished product; (5) Finished product heat treatment annealing process: The finished product after aluminum foil rolling and slitting is subjected to low-temperature heat treatment annealing to obtain high-deep-drawing battery soft packaging foil, wherein the finished product heat treatment annealing process is set to a temperature range of 200~240℃.

2. The processing method according to claim 1, characterized in that: Before step (1), the performance of the hot-rolled finished product is tested to verify the quality of the hot-rolled coil.

3. The processing method according to claim 1, characterized in that: In step (2), the intermediate heat treatment annealing process is set to a temperature range of 400-440°C and a continuous annealing time of 4-12 hours.

4. The processing method according to claim 1, characterized in that: In step (4), during the foil rolling and slitting process, the foil rolling thickness changes as follows: For (b), 0.26 mm-0.13 mm-0.08 mm-0.04 mm; For (a), 0.30 mm-0.15 mm-0.09 mm-0.055 mm.

5. The processing method according to claim 1, characterized in that: In step (5), a low-temperature heat treatment annealing treatment is performed to promote the formation of fine and uniform recrystallized grains, significantly improve the deep drawing performance of the aluminum foil and improve the adhesion between aluminum foils. The deep drawing performance of the aluminum foil is improved by 10% to 15%, the battery electrolyte filling amount is increased by 10% to 20%, and the energy density is increased by 8% to 10%.

6. A high-deep-drawing battery soft packaging foil, which is prepared by the processing method according to any one of claims 1 to 5.

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