WO2022160409A1

WO2022160409A1 - Processing method for battery aluminum foil

Info

Publication number: WO2022160409A1
Application number: PCT/CN2021/078940
Authority: WO
Inventors: 陈登斌; 曹城; 章国华; 宋盼; 杨洪辉; 李汉文; 侯志文; 许泽辉
Original assignee: 永杰新材料股份有限公司; 浙江永杰铝业有限公司
Priority date: 2021-01-28
Filing date: 2021-03-03
Publication date: 2022-08-04
Also published as: KR102609847B1; KR20220110721A

Abstract

A processing method for a battery aluminum foil. The rolling parameters of the passes of foil rolling and middle rolling and the rolling time interval of two successive passes are controlled, and the rolling parameters in the finishing rolling process are controlled, such that the rolling temperature of an aluminum roll in the finishing rolling process is less than or equal to 80ºC; or the aluminum roll output during middle rolling is cooled, and the rolling parameters in the finish rolling process are controlled, such that the rolling temperature of the aluminum roll in the finishing process is less than or equal to 80ºC; or the finished aluminum roll output during the finish rolling in the cutting procedure is rapidly cooled, such that the roll temperature of the finished aluminum roll is controlled to be less than or equal to 80ºC. The attenuation degrees of the tensile strength and the percentage elongation after fracture of the battery aluminum foil obtained by using the processing method over time are greatly reduced, thereby solving the problem that the mechanical properties of an existing battery aluminum foil are greatly reduced.

Description

A kind of processing method of battery aluminum foil

technical field

The invention relates to the field of aluminum processing, in particular to a processing method of battery aluminum foil.

Background technique

With the rapid development of the pure electric new energy vehicle industry, people have put forward higher requirements for the driving range of electric vehicles. Therefore, power battery manufacturers have launched high-energy-density power batteries, and the focus of production has gradually shifted in this direction. This technical route puts forward higher requirements on the tensile strength and elongation after break of the battery aluminum foil. However, when the thickness of the current battery aluminum foil is less than 15 μm, there is a problem of mechanical property attenuation, that is, the tensile strength and elongation after fracture decrease with time, especially the elongation after fracture decreases by more than 20%.

Therefore, it is necessary to provide a new processing method of battery aluminum foil to solve the above problems.

technical problem

The purpose of the present invention is to provide a processing method of battery aluminum foil, which can effectively suppress the phenomenon that the tensile strength and elongation after breaking of the battery aluminum foil decay with time, and effectively improve the performance of the battery aluminum foil.

technical solutions

In order to achieve the above purpose, the present invention provides a processing method of battery aluminum foil, which adopts aluminum foil blank as processing material, and includes the following steps:

Step S1: Foil rolling the aluminum foil blank to obtain an aluminum strip, and then middle-rolling the aluminum strip to obtain an aluminum coil, wherein the foil rolling sequentially includes a first rolling pass and a second rolling pass the second and third rolling passes, the intermediate rolling includes the fourth rolling pass;

Step S2, finishing rolling the aluminum coil to obtain a finished aluminum coil, and the finishing rolling includes the fifth rolling pass;

Step S3: After the finished aluminum coil is off-line, the battery aluminum foil is obtained by slitting within a preset time, and the coil temperature of the finished aluminum coil is less than or equal to 80°C during slitting.

Preferably, in the step S1, during rolling, the rolling parameters of all the rolling passes of the foil rolling and the intermediate rolling and the time interval of two adjacent rolling passes are controlled, so that the intermediate rolling The coil temperature of the aluminum strip in the process is less than or equal to 75°C; wherein, the rolling parameters include reduction ratio, rolling speed, roll roughness, and oil temperature of rolling oil; in step S2, During rolling, the rolling parameters of the fifth rolling pass are controlled so that the coil temperature of the aluminum coil in the finishing rolling process is less than or equal to 80°C.

Preferably, in the step S1, after the intermediate rolling is completed, the aluminum coil is cooled so that the coil temperature of the aluminum coil is less than or equal to 75°C; in the step S2, the aluminum coil is controlled during rolling. The rolling parameters of the fifth rolling pass are such that the coil temperature of the aluminum coil in the finishing rolling process is less than or equal to 80°C.

Preferably, in the step S3, the finished aluminum coil is cut off within 30 minutes after the finished aluminum coil is taken off the line.

Preferably, in the step S1, when the foil rolling is performed, the rolling parameters for controlling the first rolling pass are: the reduction ratio is 47% to 49%, the rolling speed is 550±20m/min, the roll roughness Ra is 0.15μm, and the oil temperature is 38±2°C; the rolling parameters for controlling the second rolling pass are: the reduction ratio is 48%~50%, the rolling speed is 550±20m/min, the roll roughness Ra is 0.15μm, the oil temperature is 38±2℃; the control of the third rolling pass The rolling parameters are: the reduction ratio is 46% to 48%, the rolling speed is 550±20m/min, the roll roughness Ra is 0.15μm, and the oil temperature is 38±2°C; The first rolling pass and the second rolling pass are continuously rolled, and the aluminum foil blank after the first rolling pass and the second rolling pass is completed is naturally After cooling for 8 hours, the third rolling pass is performed to obtain the aluminum strip.

Preferably, the aluminum strip is naturally cooled for 8 hours and then subjected to the intermediate rolling to obtain the aluminum coil, wherein the rolling parameters for controlling the fourth rolling pass of the intermediate rolling are: The reduction ratio was 40% to 42%, the rolling speed was 600±20 m/min, the roll roughness Ra was 0.10 μm, and the oil temperature was 42±2°C.

Preferably, in the step S2, the aluminum coil obtained by the intermediate rolling is cooled for 8 hours, and then finishing rolling is performed to obtain the finished aluminum coil, wherein the fifth rolling is controlled during the finishing rolling. The rolling parameters of the pass are: the reduction ratio is 34% to 36%, the rolling speed is 450±20m/min, the roll roughness Ra is 0.10μm, and the oil temperature is 42±20m/min. 2°C.

Preferably, when the finished aluminum coil is obtained by performing the finishing rolling on the cooled aluminum coil, the rolling parameters for controlling the fifth rolling pass during the finishing rolling are: The reduction ratio was 34% to 36%, the rolling speed was 550±20 m/min, the roll roughness Ra was 0.10 μm, and the oil temperature was 42±2°C.

Preferably, in the step S3, by controlling the ambient temperature of the finished aluminum coil after it is off-line to be less than or equal to 30°C, the finished aluminum coil can be cut within 30 minutes after being off-line. The coil temperature reaches less than or equal to 80°C.

Preferably, in the step S3, when the ambient temperature of the finished aluminum coil after it is off-line is greater than 30°C, the finished aluminum coil is forcibly cooled, so that the finished aluminum coil can be cooled at 30°C after the finished aluminum coil is off-line. The coil temperature reaches less than or equal to 80°C when slitting within minutes.

Preferably, the forced cooling method is to set a compressed air nozzle to cool the finished aluminum coil, and the compressed air nozzle compressed air pressure dew point is less than or equal to -10°C.

Preferably, the first rolling pass is 0.24mm-0.125mm, the second rolling pass is 0.125mm-0.064mm, the third rolling pass is 0.064mm-0.034mm, and the The fourth rolling pass is 0.034mm-0.020mm, and the fifth rolling pass is 0.020mm-0.013mm.

beneficial effect

Compared with the prior art, the processing method of the battery aluminum foil of the present invention controls the rolling parameters in the finishing rolling process by controlling the rolling parameters of the passes of foil rolling and intermediate rolling, and the time interval of two adjacent passes of rolling. , so that the coil temperature of the aluminum coil in the finishing rolling process is less than or equal to 80 °C; or by cooling the aluminum coil output from the intermediate rolling and controlling the rolling parameters in the finishing rolling process, so that all The coil temperature of the aluminum coil in the finishing rolling process is less than or equal to 80°C; or by rapidly cooling the finished aluminum coil output from the finishing rolling during the slitting process, the finished aluminum coil is controlled. The coil temperature is less than or equal to 80°C; thus, the problem of suppressing the decay of tensile strength and elongation after breaking of the battery aluminum foil over time is achieved, and the processing method has high production efficiency and can be mass-produced.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, under the premise of no creative work, other drawings can also be obtained from these drawings, wherein:

Fig. 1 is a flow chart of Embodiment 1 of the battery aluminum foil processing method of the present invention;

FIG. 2 is a flow chart of Embodiment 2 of the battery aluminum foil processing method of the present invention;

FIG. 3 is a flow chart of Embodiment 3 of the battery aluminum foil processing method of the present invention;

Figure 4 is a graph showing the variation of tensile strength with time at different coil temperatures;

Fig. 5 is a graph showing the change of elongation at break with time at different coil temperatures;

Fig. 6 is the comparison diagram of the tensile strength decay curve with time of embodiment 1 and comparative example;

Fig. 7 is the contrast diagram of the elongation after break of Example 1 and the time decay curve of the comparative example;

Fig. 8 is the comparison chart of the tensile strength decay curve with time of embodiment 2 and comparative example;

Fig. 9 is the contrast diagram of the elongation after break of Example 2 and the time decay curve of the comparative example;

Fig. 10 is the comparison chart of the tensile strength decay curve with time of embodiment 3 and comparative example;

FIG. 11 is a comparison diagram of the decay curves of elongation at break with time of Example 3 and Comparative Example.

BEST MODE FOR CARRYING OUT THE INVENTION

The technical solutions in the embodiments of the present invention will be clearly and completely described 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 of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The present invention provides a processing method of battery aluminum foil, which adopts aluminum foil blank as processing material, and includes the following steps:

The processing method of the present invention controls the rolling parameters in the finishing rolling process by controlling the rolling parameters of the passes of foil rolling and intermediate rolling, the time interval of the two adjacent passes of rolling, and the finishing rolling process. The coil temperature of the aluminum coil is less than or equal to 80°C; or by cooling the aluminum coil output from the intermediate rolling and controlling the rolling parameters in the finishing rolling process, the The coil temperature of the aluminum coil is less than or equal to 80°C; or the coil temperature of the finished aluminum coil is controlled to be less than or equal to 80°C by rapidly cooling the finished aluminum coil output from the finishing rolling during the slitting process Compared with the prior art, the phenomenon that the tensile strength and elongation after breaking of the battery aluminum foil are attenuated with time can be effectively suppressed, and the performance of the battery aluminum foil is effectively improved.

Next, the present invention is described in detail in conjunction with specific embodiments:

Example 1

Referring to FIG. 1 , the present invention provides a processing method of battery aluminum foil, and the processing method of battery aluminum foil adopts aluminum foil blank as processing material.

In this embodiment, the aluminum foil blanks are made of 1060 alloy aluminum foil blanks. Alternatively, the aluminum foil blanks can also be 1235 and 1100 alloy aluminum foil blanks.

The processing method of the battery aluminum foil further comprises the following steps:

Step S1: Foil rolling the aluminum foil blank to obtain an aluminum strip, and then middle-rolling the aluminum strip to obtain an aluminum coil, wherein the foil rolling sequentially includes a first rolling pass and a second rolling pass the second and third rolling passes, the middle rolling includes the fourth rolling pass; during rolling, the rolling parameters of all the rolling passes of the foil rolling and the middle rolling and the two adjacent rolling passes are controlled. The interval time of making passes makes the coil temperature of the aluminum strip in the intermediate rolling process less than or equal to 75°C; wherein, the rolling parameters include reduction ratio, rolling speed, roll roughness, rolling Oil temperature for making oil.

Through the experimental verification of the technical scheme of the present invention, as shown in Figure 2 and Figure 3 (the 0 day in the figure is the data measured after finishing rolling off the assembly line) is the tensile strength and elongation after fracture under different coil temperatures ( 80°C, 90°C, 100°C, 110°C) versus time, it can be seen from Figure 2 that the tensile strength decreases with time, and the higher the coil temperature, the more the tensile strength decreases; 3, it can be seen that when the coil temperature is greater than or equal to 90 °C, the elongation after fracture decreases significantly with the increase of time, while when the temperature is less than or equal to 90 °C, the elongation after fracture does not change significantly with time, so in order to To overcome this problem, it is necessary to control the coil temperature before finishing rolling to be less than or equal to 90°C, preferably the coil temperature before finishing rolling in this embodiment is controlled to be no more than 80°C. In order to control the coil temperature of the aluminum strip during the intermediate rolling process to be less than or equal to 75°C, it is easier to control the coil temperature during the finishing rolling to not exceed 80°C, thereby more conducive to suppressing the tensile strength and elongation of the battery aluminum foil. The rate at which a long rate decays over time.

In this embodiment, the foil rolling is the first rolling pass, the second rolling pass and the third rolling pass; the intermediate rolling is the fourth rolling pass; the finishing rolling is the fifth rolling pass, wherein Finishing is the finished pass.

Specifically, during the foil rolling, the rolling parameters for controlling the first rolling pass are: the reduction ratio is 47% to 49%, and the rolling speed is 550±20m/min , the roughness Ra of the roll is 0.15μm, the oil temperature is 38±2°C; the rolling parameters for controlling the second rolling pass are: the reduction ratio is 48%~50%, The rolling speed is 550±20m/min, the roll roughness Ra is 0.15μm, and the oil temperature is 38±2°C; the rolling parameters for controlling the third rolling pass are: The reduction ratio is 46%~48%, the rolling speed is 550±20m/min, the roll roughness Ra is 0.15μm, and the oil temperature is 38±2℃; the first rolling pass The first and second rolling passes are continuously rolled, and the aluminum foil blanks completed by the first rolling pass and the second rolling pass are naturally cooled at room temperature for 8 hours, and then the first rolling pass is carried out. The aluminum strip is obtained by three-pass rolling; naturally cooling at room temperature for 8 hours achieves the effect of controlling the coil temperature after finishing rolling by controlling the coil temperature before finishing rolling.

In this embodiment, the first rolling pass is 0.24mm-0.125mm, that is, the reduction ratio is 47.9%; the second rolling pass is 0.125mm-0.064mm, that is, the rolling reduction The reduction rate is 48.8%; the third rolling pass is 0.064mm-0.034mm, that is, the reduction rate is 46.9%.

After the aluminum strip is naturally cooled for 8 hours, the intermediate rolling is performed to obtain the aluminum coil, wherein the rolling parameter controlling the fourth rolling pass of the intermediate rolling is: the pressure The reduction rate is 40%~42%, the rolling speed is 600±20m/min, the roll roughness Ra is 0.10μm, and the oil temperature is 42±2℃, these parameters can make the aluminum strip Make the surface of the aluminum coil uniform and fine.

In this embodiment, the fourth rolling pass is 0.034mm-0.020mm, that is, the reduction ratio is 41.2%.

Step S2: Finish rolling the aluminum coil to obtain a finished aluminum coil, the finishing rolling includes a fifth rolling pass, and the rolling parameters of the fifth rolling pass are controlled during rolling, so that the The coil temperature of the finished aluminum coil in the finishing rolling process is less than or equal to 90°C. Preferably, the coil temperature of the finished aluminum coil in the finishing rolling process in this embodiment is less than or equal to 80°C, so that the aluminum foil blank has better tensile strength and elongation after fracture, as shown in Figure 2 and It can also be analyzed from FIG. 3 that the lower the coil temperature of the finished aluminum coil is, the lower the degree of attenuation of the tensile strength and elongation after break of the finished aluminum coil over time is lower.

Specifically, in the step S2, the aluminum coil obtained by the intermediate rolling is cooled for 8 hours, and then finishing rolling is performed to obtain the finished aluminum coil, wherein the fifth rolling is controlled during the finishing rolling. The rolling parameters of the pass are: the reduction ratio is 34% to 36%, the rolling speed is 450±20m/min, the roll roughness Ra is 0.10μm, and the oil temperature is 42±20m/min. 2°C.

In this embodiment, the fifth rolling pass is 0.020mm-0.013mm, that is, the reduction ratio is 35.0%.

In this embodiment, the coil temperature measured after the finished aluminum coil obtained by the finishing rolling is 79.7°C. It can be seen from Figure 2 and Figure 3 that when the coil temperature is less than or equal to 80°C, the tensile strength and elongation after fracture of the finished aluminum coil are greatly reduced with time, and the finished aluminum coil is off-line. Post tensile strength and post fracture elongation remained stable and no longer decreased with time.

Step S3, after the finished aluminum coil is off-line, the battery aluminum foil is obtained by slitting within a preset time.

In this embodiment, the preset time after the finished aluminum coil is off-line is not limited, generally it is placed at room temperature for 6-24 hours and then slitted to obtain the battery aluminum foil.

For the battery aluminum foil prepared by the method of the present invention, the attenuation degree of its tensile strength over time is slowed down, and the tensile strength remains stable from the 12th day after the finished aluminum coil is offline; compared with the prior art , which indirectly increases the elongation at break (elongation) by suppressing the decay of the elongation at break.

In the prior art of the battery aluminum foil used for lithium ion batteries, the coil temperature after finishing rolling passes off the assembly line is all greater than 90°C. As in the comparative example provided by the present invention, the aluminum foil blank is successively subjected to foil rolling, intermediate rolling, and finishing. Rolling, standing, and then slitting; the foil rolling passes are successively 0.24mm-0.125mm-0.064mm-0.034mm three-pass continuous rolling, the rolling speed is 600±20m/min, the roll is rough The thickness Ra is 0.20μm, the oil temperature of the lubricating rolling oil is 38±2℃; the rolling pass of the middle rolling is 0.034mm-0.020mm, the rolling speed is 650±20m/min, and the roll roughness Ra is 0.15 μm, the oil temperature of the lubricating rolling oil is 42±2℃; the finishing rolling pass is 0.020mm-0.013mm, the rolling speed is 600±20m/min, the roll roughness Ra is 0.15μm, the lubricating rolling The oil temperature of the oil is 42±2℃. The coil temperature was measured at 97.9°C after the finishing rolling pass came off the assembly line.

Table 1 and Table 2 respectively show the process parameters of Example 1 of the present invention and the process parameters of the comparative example.

Table 1 shows the process parameters of Example 1 of the present invention

Table 2 is the process parameters of the comparative example

In the following, a comparative example of the prior art is compared with the present Example 1, as shown in Figure 6 and Figure 7, wherein Figure 6 is a comparison diagram of the tensile strength decay curves of Example 1 and the comparative example over time, Figure 7 is a comparison chart of the decay curve of elongation after breakage of Example 1 and the comparative example (the 0th day in the figure is the data measured after finishing rolling off the assembly line). It can be seen from the figure that the Compared with the aluminum foil obtained in the comparative example, the attenuation of the tensile strength of the aluminum foil with time slowed down, and the tensile strength maintained a stable state from the 12th day after finishing rolling off the assembly line, and no longer changed with time. Attenuation; the decay degree of elongation after breaking with time is greatly reduced. The aluminum foil obtained in this example starts on the 16th day after finishing rolling off the assembly line, and the elongation after breaking is in a stable state and no longer decays with time. However, in the prior art shown in the comparative example, the tensile strength decreases significantly with the increase of time. After 24 days, the decay rate slows down, but it is still in a state of slow decay; There was a cliff-like decline, and it didn't start to stabilize until the 20th day of the offline.

Example 2

Referring to FIG. 2 , the present invention provides a processing method of battery aluminum foil, and the processing method of battery aluminum foil adopts aluminum foil blank as processing material.

Step S1: Foil rolling the aluminum foil blank to obtain an aluminum strip, and then middle-rolling the aluminum strip to obtain an aluminum coil, wherein the foil rolling sequentially includes a first rolling pass and a second rolling pass The intermediate rolling includes the fourth rolling pass; after the intermediate rolling is completed, the aluminum coil is cooled so that the coil temperature of the aluminum coil is less than or equal to 75°C.

Specifically, the cooling is forced cooling such as natural cooling or air cooling.

Specifically, in the step S1, when the foil rolling is performed, the rolling parameters of the first rolling pass are: the reduction ratio is 47% to 49%, and the rolling speed is 600±20m/min, the roll roughness Ra is 0.20μm, the oil temperature is 38±2℃; the rolling parameters of the second rolling pass are: the reduction ratio is 48% ~50%, the rolling speed is 600±20m/min, the roll roughness Ra is 0.20μm, the oil temperature is 38±2℃; the rolling parameters of the third rolling pass are: the reduction ratio is 46% to 48%, the rolling speed is 600±20m/min, the roll roughness Ra is 0.20μm, and the oil temperature is 38±2°C; the first The aluminum strip is obtained by continuous rolling in the rolling pass, the second rolling pass and the third rolling pass; the aluminum coil is obtained by performing the intermediate rolling on the aluminum strip, wherein the intermediate rolling The rolling parameters of the fourth rolling pass are: the reduction ratio is 40% to 42%, the rolling speed is 650±20m/min, and the roll roughness Ra is 0.15 μm, the oil temperature is 42±2°C.

In this embodiment, the aluminum coil after the intermediate rolling is naturally cooled at room temperature, and the natural cooling time is greater than or equal to 10 hours. After natural cooling, the coil temperature of the aluminum coil reaches less than or equal to 75°C It is beneficial to improve the mechanical properties of battery aluminum foil, improve the quality of battery aluminum foil, and make it meet production requirements.

In this embodiment, the first rolling pass is 0.24mm~0.125mm, the second rolling pass is 0.125mm~0.064mm, and the third rolling pass is 0.064mm~0.034mm, The fourth rolling pass is 0.034mm~0.020mm; correspondingly, the reduction ratio of the first rolling pass is 47.9%, and the reduction of the second rolling pass is 47.9%. The reduction ratio was 48.8%, the reduction ratio of the third rolling pass was 46.9%, and the reduction ratio of the fourth rolling pass was 41.2%.

It should be noted that the foil rolling, the rolling speed, the oil temperature and the rolling reduction in Example 2 of the present invention are consistent with the prior art, such as those provided by the present invention. There are technical comparison ratios.

Step S2: Finish rolling the aluminum coil to obtain a finished aluminum coil, the finishing rolling includes a fifth rolling pass, and the rolling parameters of the fifth rolling pass are controlled during rolling, so that the finishing rolling During the process, the coil temperature of the aluminum coil is less than or equal to 80 ° C, which is beneficial to reduce the recovery annealing of the aluminum coil and the possible element clustering phenomenon, so as to suppress the decay of tensile strength and elongation after fracture with time. Purpose.

Specifically, the finished aluminum coil is obtained by performing the finishing rolling on the aluminum coil after natural cooling, wherein the rolling parameters for controlling the fifth rolling pass during the finishing rolling are: The reduction ratio is 34%~36%, the rolling speed is 550±20m/min, the roll roughness Ra is 0.10μm, and the oil temperature is 42±2℃. These parameters can make the The surface of the finished aluminum coil is uniform, delicate and not cracked.

In this embodiment, the fifth rolling pass is 0.020 mm to 0.013 mm, and correspondingly, the reduction ratio of the fifth rolling pass is 35.0%.

In this embodiment, the coil temperature measured after the finished aluminum coil obtained by the finishing rolling is 77.2°C. It can be seen from Figure 2 and Figure 3 that when the coil temperature is less than or equal to 80°C, the tensile strength and elongation after fracture of the finished aluminum coil are greatly reduced with time, and the finished aluminum coil is off-line. Post tensile strength and post fracture elongation remained stable and no longer decreased with time.

For the battery aluminum foil prepared by the above method of the present invention, the attenuation degree of its tensile strength over time has been slowed down, and the tensile strength remains stable from the 16th day after the finished aluminum coil is off the line; its elongation after breaking ( elongation) was improved, and the decay rate of elongation at break was suppressed.

In the prior art of the battery aluminum foil used for lithium ion batteries, the coil temperature after the finishing rolling pass was off-line was all greater than 90°C. The coil temperature was 97.9°C.

Table 3 is the process parameters of Example 2 of the present invention

In the following, the comparative example of the prior art is compared with the present Example 2, as shown in Figures 8 and 9, wherein Figure 8 is a comparison diagram of the tensile strength decay curves of Example 2 and the comparative example over time, Figure 9 is a comparison diagram of the decay curve of the elongation after fracture of Example 2 and the comparative example (the 0th day in the figure is the data measured after finishing rolling off the assembly line). It can be seen from the figure that the Compared with the aluminum foil obtained in the comparative example, the attenuation of the tensile strength of the aluminum foil with time slowed down, and the tensile strength remained stable from the 16th day after finishing rolling off the assembly line, and no longer increased with time. Attenuation; the degree of attenuation of elongation after breaking with time is greatly reduced. The aluminum foil obtained in this example starts from the 20th day after finishing rolling off the assembly line, and the elongation after breaking is basically in a stable state. However, in the prior art shown in the comparative example, the tensile strength decreases significantly with the increase of time, and the decay time is as long as more than 60 days; It didn't start to stabilize until the 20th day of the offline, but it began to decay with time after 20 days of stability. Therefore, the mechanical properties of the battery aluminum foil produced by the comparative example can no longer meet the requirements of the current new energy market, while this embodiment of the present invention solves the problem. The tensile strength of the battery aluminum foil and the elongation after breakage decay with time.

Example 3

Referring to FIG. 3 , the present invention provides a processing method of battery aluminum foil, and the processing method of battery aluminum foil adopts aluminum foil blank as processing material.

Step S1: Foil rolling the aluminum foil blank to obtain an aluminum strip, and then middle-rolling the aluminum strip to obtain an aluminum coil, wherein the foil rolling sequentially includes a first rolling pass and a second rolling pass The second and third rolling passes, the intermediate rolling includes the fourth rolling pass.

Specifically, the first rolling pass, the second rolling pass and the third rolling pass of the foil rolling are continuously rolled to obtain the aluminum strip, and after the foil rolling is completed The rolls are changed, and the fourth rolling pass and the fifth rolling pass are performed to obtain the finished aluminum coil.

Specifically, in the step S1, when the foil rolling and the intermediate rolling are performed, the rolling parameters of the first rolling pass are: the reduction ratio is 47% to 49%, the The rolling speed is 600±20m/min, the roll roughness Ra is 0.20μm, and the oil temperature is 38±2°C; the rolling parameters of the second rolling pass are: the pressure The reduction rate is 48%~50%, the rolling speed is 600±20m/min, the roll roughness Ra is 0.20μm, and the oil temperature is 38±2℃; The rolling parameters are: the reduction ratio is 46% to 48%, the rolling speed is 600±20m/min, the roll roughness Ra is 0.20μm, and the oil temperature is 38±2°C ; The rolling parameters of the fourth rolling pass of the middle rolling are: the reduction ratio is 40% to 42%, the rolling speed is 650 ± 20m/min, and the roll is rough The degree Ra was 0.15 μm, and the oil temperature was 42±2°C.

Step S2: Finish rolling the aluminum coil to obtain a finished aluminum coil, and the finishing rolling includes a fifth rolling pass; the rolling parameters of the fifth rolling pass are: the reduction ratio is: 34%~36%, the rolling speed is 600±20m/min, the roll roughness Ra is 0.15μm, and the oil temperature is 42±2℃. Specifically, these parameters can make the finished aluminum coil The surface is uniform, fine and not cracked.

It should be noted that the rolling parameters of the foil rolling, the intermediate rolling and the finishing rolling in Example 3 of the present invention are all common process steps and parameters in the prior art, such as those provided in the present invention. The parameters of the comparative example in the prior art are the same, therefore, the coil temperature of the finished aluminum coil obtained after the foil rolling, the intermediate rolling and the finishing rolling is greater than 90°C; When the finished aluminum coil is not cooled within 30 minutes, the tensile strength and post-break elongation of the battery aluminum foil obtained by slitting the finished aluminum coil both show obvious attenuation with time.

In this embodiment, the preset time is within 30 minutes after the finished aluminum coil is offline.

Specifically, by controlling the ambient temperature of the finished aluminum coil to be less than or equal to 30°C after the finished aluminum coil is off the line, the coil temperature of the finished aluminum coil can reach less than or equal to 30 minutes after being cut off the line. 80°C. More specifically, the slitting process in the step S3 has the function of constant temperature and humidity, and the ambient temperature is set to be less than or equal to 30°C, and the finished aluminum coil is directly slit; due to the environment in which the finished aluminum coil is located The temperature is less than or equal to 30°C, and the finished aluminum coil needs to be opened when slitting. Due to the characteristics of the aluminum coil, the finished aluminum coil can be rapidly cooled in a few seconds to reach the maximum temperature of the finished aluminum coil when slitting. The coil temperature is less than or equal to 80℃.

When the slitting process in the step S3 does not have the function of constant temperature and humidity and the ambient temperature of the finished aluminum coil after it is off the assembly line is greater than 30° C., the finished aluminum coil is forcedly cooled, so that the finished aluminum coil is forced to cool. After the aluminum coil is off-line, its coil temperature reaches less than or equal to 80°C when it is cut within 30 minutes; more specifically, the forced cooling method is to set a compressed air nozzle to cool the finished aluminum coil, The dew point of the compressed air pressure of the nozzle is less than or equal to -10°C to achieve the effect of forcibly cooling the finished aluminum coil, and the finished aluminum coil needs to be opened when it is slit, so the finished aluminum coil can be The coil temperature is less than or equal to 80°C in a short time.

Among them, the air pressure dew point is an indicator to measure the water content in the compressed air. If the water content in the compressed air is too high, the aluminum foil will be oxidized and corroded.

In this embodiment, the finished aluminum coil is cut within 30 minutes after it is offline, and the coil temperature of the finished aluminum coil is less than or equal to 80°C during slitting, which is beneficial to the improvement of the mechanical properties of the battery aluminum foil. Improve the quality of the battery aluminum foil to meet the production requirements, and the slitting method can reduce the recovery annealing of the battery aluminum foil and the possible existence of trace element clusters, so as to suppress the tensile strength and the elongation after breaking. Decay with time the goal of.

Through the experimental verification of the technical scheme of the present invention, as shown in Figure 2 and Figure 3 (the 0 day in the figure is the data measured after finishing rolling off the assembly line) is the tensile strength and elongation after fracture under different coil temperatures ( 80°C, 90°C, 100°C, 110°C) versus time, it can be seen from Figure 2 that the tensile strength decreases with time, and the higher the coil temperature, the more the tensile strength decreases, that is, the attenuation The greater the degree, and when the coil temperature does not exceed 90 °C, the degree of tensile strength attenuation is significantly improved; it can be seen from Figure 3 that when the coil temperature is greater than or equal to 90 °C, the elongation after fracture increases with time. When the temperature is less than or equal to 90 ℃, the elongation after breaking does not change significantly with time, so in order to overcome this problem, it is necessary to cool the finished aluminum coil within 30 minutes after it is offline, and the coil temperature The temperature is controlled to be less than or equal to 90°C. Preferably, the finished aluminum coil is cooled to make the coil temperature less than or equal to 80°C when the slitting process is performed after the finishing rolling is completed in this embodiment, so as to help suppress the battery aluminum foil. The rate at which tensile strength and elongation at break decay with time.

In this embodiment, the coil temperature of the finished aluminum coil obtained by the finishing rolling is 99.7° C. after being off-line, and the slitting is carried out in an environment where the room temperature is 24° C. after 23 minutes of being off-line. Due to the characteristics of the aluminum coil, the When the finished aluminum coil is opened at a room temperature of 24°C, the coil temperature will drop rapidly, achieving the effect of cooling the coil temperature to 75°C in a relatively short period of time. It can be seen from Figure 2 and Figure 3 that when the coil temperature is less than or equal to 80°C, the tensile strength and elongation after fracture of the finished aluminum coil are greatly reduced with time, and the finished aluminum coil is off-line. Post tensile strength and post fracture elongation remained stable and no longer decreased with time.

The battery aluminum foil prepared by the above-mentioned method of the present invention has a reduced degree of attenuation of its tensile strength over time, and a slower rate of attenuation of its tensile strength with time; its elongation after fracture (elongation) is improved, and the The rate of decay of elongation after fracture.

In the prior art of the battery aluminum foil used for lithium ion batteries, the finished aluminum coils after finishing rolling are not cooled down within 30 minutes after the finishing rolling is finished. The temperature of the obtained coil is 97.9 ° C; the finished product is placed off the line for 24 hours for slitting, and due to the long standing time, the product cannot reduce the temperature of the aluminum coil in a short time, so this method produces Compared with the aluminum coil of the present invention, its tensile strength and elongation after break both decay faster with time, and its decay period is relatively long.

Table 4 is the process parameter of embodiment 3 of the present invention

In the following, the comparative example of the prior art is compared and explained with the present Example 3, as shown in Figure 10 and Figure 11, wherein, Figure 10 is a comparison diagram of the tensile strength decay curve with time of Example 3 and the comparative example, Figure 11 is a comparison chart of the decay curve of elongation after fracture of Example 3 and the comparative example (the 0 day in the figure is the data measured after finishing rolling off the assembly line). It can be seen from the figure that the Compared with the aluminum foil obtained in the comparative example, the decay rate of the tensile strength of the aluminum foil decreased with time, and the tensile strength maintained a stable state from the 40th day after finishing rolling off the assembly line, and no longer changed with time. However, the tensile strength of the comparative example continued to decay on the 40th day after finishing rolling; the decay degree of elongation after fracture with time was greatly reduced, and the decay rate slowed down. However, in the prior art shown in the comparative example, the tensile strength decreases significantly with the increase of time, and the decay time is as long as more than 60 days; The decay rate did not decrease until the 20th day off the production line, so the mechanical properties of the battery aluminum foil produced by the comparative example could no longer meet the requirements of the current new energy market, while this embodiment of the present invention solves the tensile strength of the battery aluminum foil. The problem of strength and elongation at break decay with time.

The present invention provides one embodiment of the present invention as described above, which is not intended to limit the scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied In other related technical fields, they are all included within the scope of patent protection of the present invention.

Claims

A processing method of battery aluminum foil, characterized in that the processing method of battery aluminum foil adopts aluminum foil blank as processing material, comprising the following steps:

Step S1: Foil rolling the aluminum foil blank to obtain an aluminum strip, and then middle-rolling the aluminum strip to obtain an aluminum coil, wherein the foil rolling sequentially includes a first rolling pass and a second rolling pass the second and third rolling passes, the intermediate rolling includes the fourth rolling pass;

Step S2, finishing rolling the aluminum coil to obtain a finished aluminum coil, and the finishing rolling includes the fifth rolling pass;

Step S3: After the finished aluminum coil is off-line, the battery aluminum foil is obtained by slitting within a preset time, and the coil temperature of the finished aluminum coil is less than or equal to 80°C during slitting.
The method for processing battery aluminum foil according to claim 1, characterized in that, in the step S1, during rolling, the rolling parameters of all the rolling passes of the foil rolling and the intermediate rolling and the adjacent two rolling parameters are controlled. The time interval of each rolling pass makes the coil temperature of the aluminum strip in the intermediate rolling process less than or equal to 75°C; wherein, the rolling parameters include reduction ratio, rolling speed, roll roughness , the oil temperature of the rolling oil; in the step S2, the rolling parameters of the fifth rolling pass are controlled during rolling, so that the coil temperature of the aluminum coil in the finishing rolling process is less than or equal to 80°C.
The method for processing battery aluminum foil according to claim 1, wherein in the step S1, after the intermediate rolling is completed, the aluminum coil is cooled so that the coil temperature of the aluminum coil is less than or equal to 75 °C; in the step S2, the rolling parameters of the fifth rolling pass are controlled during rolling, so that the coil temperature of the aluminum coil in the finishing rolling process is less than or equal to 80 °C.
The processing method of battery aluminum foil according to claim 1, characterized in that, in the step S3, the finished aluminum coil is cut off within 30 minutes after being off-line.
The method for processing battery aluminum foil according to claim 2, wherein in the step S1, when the foil rolling is performed, the rolling parameter for controlling the first rolling pass is: the pressure The rolling rate is 47%~49%, the rolling speed is 550±20m/min, the roll roughness Ra is 0.15μm, and the oil temperature is 38±2℃; the second rolling pass is controlled The rolling parameters are: the reduction rate is 48%~50%, the rolling speed is 550±20m/min, the roll roughness Ra is 0.15μm, and the oil temperature is 38±2 ℃; the rolling parameters controlling the third rolling pass are: the reduction ratio is 46% to 48%, the rolling speed is 550±20 m/min, and the roll roughness Ra is 0.15μm, the oil temperature is 38±2°C; the first rolling pass and the second rolling pass are continuously rolled, and the first rolling pass and the second rolling pass are continuously rolled. The aluminum foil blank after the pass is naturally cooled at room temperature for 8 hours, and then the third rolling pass is performed to obtain the aluminum strip.
The processing method of battery aluminum foil according to claim 5, wherein the aluminum coil is obtained by performing the intermediate rolling after the aluminum strip is naturally cooled for 8 hours, wherein the The rolling parameters of the fourth rolling pass are: the reduction ratio is 40% to 42%, the rolling speed is 600±20 m/min, the roll roughness Ra is 0.10 μm, the The oil temperature is 42±2℃.
The processing method of battery aluminum foil according to claim 6, characterized in that, in the step S2, the aluminum coil obtained by the intermediate rolling is cooled for 8 hours, and then finish rolling is performed to obtain the finished aluminum coil, Wherein, the rolling parameters for controlling the fifth rolling pass during the finishing rolling are: the reduction ratio is 34%-36%, the rolling speed is 450±20m/min, the roll The roughness Ra was 0.10 μm, and the oil temperature was 42±2°C.
The processing method of battery aluminum foil according to claim 3, characterized in that, when the finished aluminum coil is obtained by performing the finishing rolling on the cooled aluminum coil, wherein the finishing rolling is performed to control the The rolling parameters of the fifth rolling pass are: the reduction ratio is 34% to 36%, the rolling speed is 550±20 m/min, the roll roughness Ra is 0.10 μm, the The oil temperature is 42±2℃.
The processing method of battery aluminum foil according to claim 4, characterized in that, in step S3, by controlling the ambient temperature of the finished aluminum coil after it is off-line to be less than or equal to 30°C, the After the finished aluminum coil is off-line, its coil temperature reaches less than or equal to 80°C when slitting within 30 minutes.
The processing method of battery aluminum foil according to claim 4, characterized in that, in step S3, when the ambient temperature of the finished aluminum coil after it is offline is greater than 30°C, the finished aluminum coil is processed Forced cooling, so that the coil temperature of the finished aluminum coil reaches less than or equal to 80° C. within 30 minutes after being cut off the line.
The processing method of battery aluminum foil according to claim 10, wherein the forced cooling method is to set a compressed air nozzle to cool the finished aluminum coil, and the compressed air nozzle compressed air pressure dew point is less than or equal to - 10°C.
The method for processing battery aluminum foil according to claims 7 to 10, wherein the first rolling pass is 0.24mm-0.125mm, the second rolling pass is 0.125mm-0.064mm, and the The third rolling pass is 0.064mm-0.034mm, the fourth rolling pass is 0.034mm-0.020mm, and the fifth rolling pass is 0.020mm-0.013mm.