Battery aluminum foil and method for manufacturing the same

Abstract

The application relates to a battery aluminum foil and a preparation method thereof. The preparation method comprises the following steps: S10, adopting first rolling oil to perform first rolling thinning treatment on aluminum foil blank, preparing aluminum foil intermediate with a thickness of 0.021mm-0.023mm, and the first rolling thinning treatment comprises rough rolling treatment and medium rolling treatment. S20, adopting second rolling oil to simultaneously perform second rolling thinning treatment and surface roughening treatment on the aluminum foil intermediate, and preparing surface-roughened aluminum foil with a thickness of 0.012mm-0.013mm. S30, performing corona treatment on the surface-roughened aluminum foil, and preparing the battery aluminum foil. The preparation method can obtain the battery aluminum foil with high adhesion and good surface quality, when the battery aluminum foil is used as a battery current collector, the combination strength and stability with electrode film layer materials can be increased, and thus the requirements of high performance and high safety of the battery can be more effectively met.

Description

Technical Field

[0001] This application relates to the field of aluminum foil rolling technology, and in particular to a battery aluminum foil and its preparation method. Background Technology

[0002] With the development of new energy vehicles, the demand for power batteries has grown rapidly. Current collectors are one of the key components in power batteries, and battery aluminum foil, as the positive electrode current collector material for lithium-ion batteries, has been widely used. In recent years, the development of power batteries has entered the stage of large modules and module-free production, placing higher demands on the thickness precision and consistency, shape, and surface quality of battery aluminum foil. Among these, surface quality directly affects the adhesion between the battery aluminum foil and the electrode film, thus impacting the safety, stability, and cycle life of the power battery.

[0003] Traditional techniques involve rolling finished battery aluminum foil to create patterns on its surface. While this method improves the roughness of the aluminum foil and enhances the adhesion between the foil and the electrode film, the dry friction rolling process without the addition of rolling oil means that aluminum powder and debris generated during rolling cannot be removed promptly. This can lead to foreign matter being pressed in, reducing the surface quality of the battery aluminum foil.

[0004] Therefore, how to prepare battery aluminum foil with high adhesion and good surface quality has become an urgent technical problem to be solved. Summary of the Invention

[0005] Therefore, it is necessary to provide a battery aluminum foil with high adhesion and good surface quality, and a method for preparing the same.

[0006] The first aspect of this application provides a method for preparing battery aluminum foil, comprising the following steps:

[0007] S10. The aluminum foil blank is subjected to a first rolling thinning treatment using a first rolling oil to prepare an aluminum foil intermediate with a thickness of 0.021 mm to 0.023 mm. The first rolling thinning treatment includes rough rolling and intermediate rolling.

[0008] S20. The aluminum foil intermediate is subjected to a second rolling thinning treatment and a surface roughening treatment simultaneously using a second rolling oil to prepare a surface roughened aluminum foil with a thickness of 0.012 mm to 0.013 mm.

[0009] S30. The surface roughened aluminum foil is subjected to corona treatment to prepare the battery aluminum foil.

[0010] The above preparation method first employs a first rolling oil for a first rolling thinning treatment to thin the aluminum foil blank, thereby obtaining an aluminum foil intermediate with a thickness of 0.021 mm to 0.023 mm and a relatively smooth surface. Subsequently, in the presence of a second rolling oil, the aluminum foil intermediate undergoes a second rolling thinning treatment and a roughening treatment simultaneously, further reducing the thickness of the aluminum foil intermediate to meet the thickness requirements of battery-grade aluminum foil, and forming roughening textures on its surface, thus obtaining a surface-roughened aluminum foil with a thickness of 0.012 mm to 0.013 mm. Next, corona treatment removes residual rolling oil from the surface-roughened aluminum foil to alleviate the problem of increased oil content caused by surface roughening, thereby obtaining a battery aluminum foil with high adhesion. Furthermore, since the rolling process is carried out in the presence of both the first and second rolling oils, aluminum powder and debris generated during rolling can be carried away by the rolling oil, effectively alleviating the problem of foreign matter intrusion and improving the surface quality of the obtained battery aluminum foil. When this aluminum foil is used as a current collector in a battery, it can increase the bonding strength with the electrode film, thereby more effectively meeting the requirements of high performance and high safety of the battery.

[0011] Furthermore, since this application is an improvement on the traditional standard battery aluminum foil production process, it has almost no impact on production efficiency and has wide applicability.

[0012] In some embodiments, the preparation method satisfies at least one of the conditions in (1) to (2):

[0013] (1) The first rolling oil includes base oil and lubricating additives, and the mass percentage of the lubricating additives is 6.5wt% to 8.0wt% based on the total mass of the first rolling oil.

[0014] (2) The second rolling oil includes base oil and lubricating additives, and the mass percentage of the lubricating additives is 6.0 wt% to 7.5 wt% based on the total mass of the second rolling oil.

[0015] In some embodiments, the preparation method satisfies at least one of the conditions in (3) to (6):

[0016] (3) The base oil of the first rolling oil includes No. 80 base oil;

[0017] (4) The lubricating additives in the first rolling oil include lauric acid;

[0018] (5) The base oil of the second rolling oil includes No. 80 base oil;

[0019] (6) The lubricating additives in the second rolling oil include lauric acid.

[0020] In some embodiments, the preparation method satisfies at least one of the conditions in (7) to (10):

[0021] (7) The temperature of the first rolling oil is 40℃~45℃;

[0022] (8) The temperature of the second rolling oil is 45℃~50℃;

[0023] (9) The spray rate of the first rolling oil is 1100L / min to 1500L / min;

[0024] (10) The spraying rate of the second rolling oil is 700L / min to 900L / min.

[0025] In some embodiments, the preparation method satisfies at least one of the conditions in (11) to (12):

[0026] (11) The rolling speed of the first rolling thinning process is 500m / min to 700m / min;

[0027] (12) The rolling speed of the second rolling thinning process is 400m / min to 600m / min.

[0028] In some embodiments, step S10 includes the following steps:

[0029] S101. The aluminum foil blank is subjected to rough rolling treatment using the first rolling oil to reduce the thickness of the aluminum foil blank to 0.045mm to 0.050mm;

[0030] S102. The aluminum foil blank after rough rolling is subjected to intermediate rolling treatment using the first rolling oil to prepare the aluminum foil intermediate with a thickness of 0.021mm to 0.023mm.

[0031] In some embodiments, step S10 is performed using a work roller with a smooth surface.

[0032] In some embodiments, step S20 is performed using a texturing work roller, the surface of which includes a plurality of raised texturing points, and the preparation method satisfies at least one of the conditions in (13) to (15):

[0033] (13) The height of the fibrous point is 0.002 mm to 0.02 mm;

[0034] (14) The outer diameter of the fibrous point is 0.005 mm to 0.5 mm;

[0035] (15) The density of the tufted points is 5 per mm. 2 ~50 pieces / mm 2.

[0036] In some embodiments, the corona treatment uses a corona power of 28kW to 32kW and a corona velocity of 80m / min to 160m / min.

[0037] A second aspect of this application provides a method for preparing battery aluminum foil using the preparation method of the first aspect. Attached Figure Description

[0038] Figure 1 This is a scanning electron microscope image of the battery aluminum foil prepared in Example 1.

[0039] Figure 2 This is a scanning electron microscope image of the battery aluminum foil prepared in Comparative Example 1. Detailed Implementation

[0040] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0042] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0043] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the weights mentioned in the embodiments of this application can be well-known units of mass in the chemical industry, such as μg, mg, g, and kg.

[0044] The bonding strength between the battery aluminum foil and the electrode film layer affects the battery's safety performance. If the bonding between the two is weak, the electrode film layer will separate from the battery aluminum foil during charging and discharging, leading to increased internal resistance and heat generation, thus posing a serious safety hazard. Traditional technology roughens the surface of the smooth finished battery aluminum foil to enhance its adhesion and improve the bonding strength with the electrode film layer. However, this method involves rolling under dry friction without adding rolling oil, resulting in poor lubrication between the rolls and the finished battery aluminum foil. Consequently, more debris and aluminum powder are generated during rolling, and these debris and aluminum powder cannot be removed in time, increasing the risk of foreign matter being pressed into the surface of the battery aluminum foil and reducing its surface quality. Furthermore, this method increases production steps, reduces production efficiency, and is only suitable for small-batch, small-roll weight, and small-scale product production.

[0045] Based on this, the technicians took a different approach, simultaneously thinning and roughening the aluminum foil during the preparation process of the battery aluminum foil. By combining rolling oil and optimizing the degreasing process, they obtained battery aluminum foil with high adhesion and good surface quality.

[0046] One embodiment of this application provides a method for preparing battery aluminum foil, including the following steps S10 to S30.

[0047] S10. The aluminum foil blank is subjected to a first rolling thinning treatment using the first rolling oil to prepare an aluminum foil intermediate with a thickness of 0.021mm to 0.023mm. The first rolling thinning treatment includes rough rolling and intermediate rolling.

[0048] Understandably, performing the first rolling thinning process in the presence of the first rolling oil can improve the lubricity of the aluminum foil blank surface, effectively reduce and remove the debris and aluminum powder generated during the rolling process, alleviate the problem of foreign matter pressing in during the rolling process, and thus obtain an aluminum foil intermediate with a thickness of 0.021mm to 0.023mm and a good surface quality.

[0049] In some embodiments, the aluminum foil blank has a thickness of 0.22 mm to 0.35 mm and a tensile strength greater than 140 MPa.

[0050] In some embodiments, the aluminum foil blank has a convexity of 0.1% to 0.6%, a thickness difference of less than 1.0%, and no obvious shape defects when uncoiling.

[0051] In some embodiments, the aluminum foil is rolled using an 1850mm series battery foil rolling mill, and the width of the aluminum foil blank is ≤1550mm.

[0052] In some embodiments, a 2150mm series battery foil rolling mill is used for rolling, and the width of the aluminum foil blank is <1900mm.

[0053] Using the above-mentioned aluminum foil blanks can further improve the surface quality and plate properties of the aluminum foil intermediate, and also improve its mechanical strength, providing a basis for preparing surface roughened aluminum foil with better surface quality.

[0054] In some embodiments, the first rolling oil comprises a base oil and a lubricating additive, wherein the mass percentage of the lubricating additive is 6.5 wt% to 8.0 wt% based on the total mass of the first rolling oil. Optionally, the mass percentage of the lubricating additive may be 6.5 wt%, 7.0 wt%, 7.5 wt%, or 8.0 wt%, and other suitable selections may be made within the range of 6.5 wt% to 8.0 wt%.

[0055] In some embodiments, the base oil of the first rolling oil includes No. 80 base oil.

[0056] In some embodiments, the lubricating additive for the first rolling oil includes lauric acid.

[0057] Using the aforementioned first rolling oil can effectively improve the lubrication system, enhance the lubrication effect, and thus improve the surface quality of the aluminum foil intermediate.

[0058] In some embodiments, the temperature of the first rolling oil is 40°C to 45°C. Optionally, the temperature of the rolling oil can be 40°C, 41°C, 42°C, 43°C, 44°C, or 45°C, and other suitable selections can be made within the range of 40°C to 45°C.

[0059] In some embodiments, the spray rate of the first rolling oil is 1100 L / min to 1500 L / min. Optionally, the spray rate of the rolling oil can be 1100 L / min, 1200 L / min, 1300 L / min, 1400 L / min, or 1500 L / min, and other suitable selections can be made within the range of 1100 L / min to 1500 L / min. In some embodiments, the rolling speed of the first rolling thinning process is 500 m / min to 700 m / min. Optionally, the rolling speed of the first rolling thinning process can be 4500 m / min, 550 m / min, 600 m / min, 650 m / min, or 700 m / min, and other suitable selections can be made within the range of 400 m / min to 700 m / min, for example, 500 m / min to 600 m / min.

[0060] The first rolling thinning process using the above rolling technology can be combined with the lubrication system to obtain an aluminum foil intermediate with a certain thickness, high thickness uniformity, good plate shape and surface quality.

[0061] In some embodiments, step S10 includes the following steps:

[0062] S101. The aluminum foil blank is rough rolled using the first rolling oil to reduce the thickness of the aluminum foil blank to 0.045mm~0.050mm;

[0063] S102. The aluminum foil blank after rough rolling is subjected to intermediate rolling treatment using the first rolling oil to prepare an aluminum foil intermediate with a thickness of 0.021mm to 0.023mm.

[0064] By performing rough rolling and intermediate rolling processes on aluminum foil blanks, the thickness and surface quality of the aluminum foil intermediates can be better controlled. Understandably, rough rolling includes at least one rough rolling pass, for example, two rough rolling passes. Similarly, intermediate rolling also includes at least one pass. It should be noted that those skilled in the art can design the specific number of passes for rough rolling and intermediate rolling according to actual needs, and this application does not limit this.

[0065] In some embodiments, step S10 is performed using a smooth-surfaced work roll. Understandably, using a smooth-surfaced work roll results in a smooth-surfaced aluminum foil intermediate. Exemplarily, the smooth-surfaced work roll is the roll used in conventional battery aluminum foil rolling processes. Furthermore, if a roughened work roll (i.e., a non-smooth-surfaced work roll) is used in the first rolling thinning process, although it can form roughening lines on the surface of the aluminum foil blank, these lines will be covered in the second rolling thinning process, not only reducing the roughening effect but also increasing the risk of strip breakage during aluminum foil rolling.

[0066] In some embodiments, the crown of the untextured work roll is 20% to 60%. When the crown is in this range, the shape of the aluminum foil intermediate can be further improved.

[0067] S20. The aluminum foil intermediate is subjected to a second rolling thinning treatment and a surface roughening treatment simultaneously using a second rolling oil to prepare a surface roughened aluminum foil with a thickness of 0.012 mm to 0.013 mm.

[0068] Understandably, in the presence of the second rolling oil, the second rolling thinning and roughening processes are performed simultaneously, causing the aluminum foil intermediate to reduce its thickness while forming surface roughening textures, thereby obtaining an aluminum foil of suitable thickness and with a roughened surface. This improves the adhesion of the resulting battery aluminum foil and further enhances its bonding strength with the electrode film layer.

[0069] In some embodiments, the surface roughening texture includes embossed patterns.

[0070] In some embodiments, the second rolling oil comprises a base oil and a lubricating additive, wherein the lubricating additive comprises 6.0 wt% to 7.5 wt% by weight of the total weight of the rolling oil. Optionally, the lubricating additive may comprise 6.0 wt%, 6.5 wt%, 7.0 wt%, or 7.5 wt%, and other suitable selections may be made within the range of 6.0 wt% to 7.5 wt%.

[0071] In some embodiments, the base oil of the second rolling oil includes No. 80 base oil.

[0072] In some of these embodiments, the additives in the second rolling oil include lauric acid.

[0073] Understandably, during the rolling process of the aluminum foil intermediate with a thickness of 0.021 mm to 0.023 mm in step S20, the surface lubrication state changes from mixed lubrication to fluid lubrication. At this time, the oil film formed by the second rolling oil can cause the aluminum foil intermediate to separate from the rolls, which has a certain impact on the surface roughening effect. This embodiment optimizes the composition and content of the second rolling oil to effectively reduce the oil film shielding effect, allowing the aluminum foil intermediate to make full contact with the rolls, improving the roughening effect, and obtaining a surface-roughened aluminum foil with clear roughening texture.

[0074] In some embodiments, the temperature of the second rolling oil is 45°C to 50°C. Optionally, the temperature of the rolling oil can be 45°C, 46°C, 47°C, 48°C, 49°C, or 50°C, and other suitable selections can be made within the range of 45°C to 50°C.

[0075] In some embodiments, the spray rate of the second rolling oil is 700 L / min to 900 L / min. Optionally, the spray rate of the rolling oil can be 700 L / min, 750 L / min, 800 L / min, 850 L / min or 900 L / min, and other suitable selections can be made within the range of 700 L / min to 900 L / min.

[0076] By adjusting the temperature and spray volume of the second rolling oil, the effects of the second rolling thinning and roughening treatments can be further improved, resulting in surface roughening aluminum foil with clear surface roughening texture, uniform thickness, good plate shape, and high surface quality.

[0077] In some embodiments, the rolling speed of the second rolling thinning process is 400 m / min to 600 m / min. Optionally, the rolling speed of the second rolling thinning process can be 400 m / min, 450 m / min, 500 m / min, 550 m / min or 600 m / min, and the above rolling speed can also be other suitable selections within the range of 400 m / min to 600 m / min, such as 500 m / min to 600 m / min, 480 m / min to 600 m / min or 500 m / min to 580 m / min.

[0078] Understandably, during the roughening process of aluminum foil intermediates, the surface of the intermediates experiences significant friction, leading to increased thermal convexity and further affecting the shape of the battery aluminum foil. This embodiment effectively balances the adverse effects of increased thermal convexity on the shape by reducing the rolling speed of conventional rolling processes, ensuring the shape of the resulting roughened aluminum foil. Furthermore, faster rolling speeds result in a stronger oil film shielding effect. The rolling speed of 400 m / min to 600 m / min in this embodiment effectively disrupts the fluid lubrication state of the aluminum foil intermediate surface, enhancing the contact between the rolls and the intermediate, thereby improving the roughening effect.

[0079] In some embodiments, step S20 is performed using a texturing work roller, the surface of which includes a plurality of raised texturing points.

[0080] Optionally, the height of the texturing point is 0.002 mm to 0.02 mm. For example, the height of the texturing point can be 0.002 mm, 0.005 mm, 0.010 mm, 0.012 mm, 0.014 mm, 0.015 mm, 0.018 mm, or 0.02 mm. Other suitable selections within the range of 0.002 mm to 0.02 mm are also possible, such as 0.010 mm to 0.015 mm. It should be noted that the height of the texturing point refers to the maximum thickness difference between the highest point of the texturing point and the texturing groove.

[0081] Optionally, the outer diameter of the fibrous point is 0.005 mm to 0.5 mm. For example, the outer diameter of the fibrous point can be 0.005 mm, 0.01 mm, 0.05 mm, 0.10 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm, 0.40 mm, 0.45 mm, or 0.5 mm. Other suitable selections within the range of 0.005 mm to 0.5 mm are also possible, such as 0.015 mm to 0.020 mm. Further optionally, the cross-section of the fibrous point is circular.

[0082] Optionally, the density of the fibrous dots is 5 dots / mm.2 ~50 pieces / mm 2 For example, the density of the fuzzy dots can be 5 dots / mm. 2 15 pieces / mm 2 20 pieces / mm 2 25 pieces / mm 2 30 pieces / mm 2 35 pieces / mm 2 40 pieces / mm 2 45 pieces / mm 2 Or 50 pieces / mm 2 The density of the fuzzy dots can also be 5 dots / mm. 2 ~50 pieces / mm 2 Other suitable options can be made, such as 15 pieces / mm. 2 ~20 pieces / mm 2 .

[0083] By employing a roughening work roller with roughening points on its surface and further controlling the height, size, and density of the roughening points, embossed patterns of specific size, depth, and density can be formed on the surface of the aluminum foil intermediate. This roughened surface can adapt to the particle size of the battery film material, thus more effectively improving the bonding strength between the obtained battery aluminum foil and the electrode film.

[0084] In some embodiments, a smooth-surfaced work roll is laser-textured to prepare a texturized work roll.

[0085] In some embodiments, the crown of the texturing work roll is 20% to 60%. When the crown is in this range, the shape of the surface-roughened aluminum foil can be further improved, thereby improving the shape of the battery aluminum foil.

[0086] In some embodiments, the following steps are included after step S20 and before step S30: surface inspection and slitting of the surface-roughened aluminum foil. Understandably, the surface-roughened aluminum foil is inspected according to conventional requirements. If the requirements are met, subsequent processing is performed on the surface-roughened aluminum foil; if the requirements are not met, it is determined to be a defective product and no further processing is required.

[0087] S30. Corona treatment is performed on the surface roughened aluminum foil to prepare battery aluminum foil.

[0088] Understandably, compared to smooth aluminum foil, roughened aluminum foil has a significantly increased oil content. If the rolling oil on the aluminum foil surface cannot be effectively removed, it will reduce its bonding strength with the electrode film layer. Therefore, this application uses corona treatment to reduce the oil content of roughened aluminum foil, thereby improving the adhesion of the battery aluminum foil.

[0089] In some embodiments, the corona power during corona treatment is 28kW to 32kW. Optionally, the corona power can be 28kW, 29kW, 30kW, 31kW, or 32kW, and other suitable selections can be made within the range of 28kW to 32kW. When the corona power is within the above range, the amount of oil on the roughened aluminum foil surface can be effectively reduced. For example, corona treatment is performed at 50% to 75% of the main power corresponding to the discharge of the corona roller.

[0090] In some embodiments, the corona treatment speed is 80 m / min to 160 m / min. Optionally, the corona treatment speed can be 80 m / min, 90 m / min, 100 m / min, 110 m / min, 120 m / min, 130 m / min, 140 m / min, 150 m / min, or 160 m / min. Other suitable selections within the range of 80 m / min to 160 m / min are also possible, such as 100 m / min to 160 m / min or 120 m / min to 150 m / min. Compared to the traditional corona treatment process for battery aluminum foil, this embodiment uses a relatively low corona treatment speed, which can more effectively remove residual rolling oil from the roughened aluminum foil surface, thereby compensating for the increased oil content caused by the roughening of the aluminum foil surface. It should be noted that the corona treatment speed refers to the production speed of the corona treatment machine.

[0091] The above preparation method first employs a first rolling oil for a first rolling thinning treatment to thin the aluminum foil blank, thereby obtaining an aluminum foil intermediate with a thickness of 0.021 mm to 0.023 mm and a relatively smooth surface. Subsequently, in the presence of a second rolling oil, the aluminum foil intermediate undergoes a second rolling thinning treatment and a roughening treatment simultaneously, further reducing the thickness of the aluminum foil intermediate to meet the thickness requirements of battery-grade aluminum foil, and forming roughening textures on its surface, thus obtaining a surface-roughened aluminum foil with a thickness of 0.012 mm to 0.013 mm. Next, corona treatment removes residual rolling oil from the surface-roughened aluminum foil to alleviate the problem of increased oil content caused by surface roughening, thereby obtaining a battery aluminum foil with high adhesion. Furthermore, since the rolling process is carried out in the presence of both the first and second rolling oils, aluminum powder and debris generated during rolling can be carried away by the rolling oil, effectively alleviating the problem of foreign matter intrusion and improving the surface quality of the obtained battery aluminum foil. When this aluminum foil is used as a current collector in a battery, it can increase the bonding strength with the electrode film, thereby more effectively meeting the requirements of high performance and high safety of the battery.

[0092] Furthermore, since the above method is an improvement on the traditional standard battery aluminum foil production process, it has almost no impact on production efficiency and has wide applicability.

[0093] Another embodiment of this application provides a battery aluminum foil, prepared using the above-described method for preparing battery aluminum foil. Understandably, the battery aluminum foil can be used as a positive electrode current collector for lithium-ion batteries and lithium batteries, and also as a positive electrode current collector and a negative electrode current collector for sodium-ion batteries.

[0094] Furthermore, this application also provides a battery electrode sheet, which includes a current collector and an electrode film layer disposed on the current collector. The current collector includes the aforementioned battery aluminum foil. Understandably, the raw materials for preparing the aforementioned electrode film layer may be conductive carbon, positive electrode active materials for lithium-ion batteries (e.g., lithium iron phosphate positive electrode materials, lithium nickel cobalt manganese ternary positive electrode materials), active positive electrode materials for sodium-ion batteries, or negative electrode active materials for sodium-ion batteries.

[0095] Furthermore, this application also provides a battery including the aforementioned battery electrodes. It is understood that the battery includes, but is not limited to, lithium-ion batteries or sodium-ion batteries.

[0096] The following are specific examples.

[0097] Example 1

[0098] 1. Preparation of laser texturing work roll

[0099] The first thinning process of aluminum foil is achieved using a roughing mill, the second thinning process using a medium mill, and the third surface roughening process using a finishing mill. The work rolls of the roughing and medium mills are unroughened, smooth-surfaced rolls; the work rolls of the finishing mill are roughened rolls. The specific manufacturing process is as follows:

[0100] Laser texturing equipment is used to perform laser-ordered texturing on the work rolls of an aluminum foil finishing mill, forming multiple raised texturing points on the surface of the work rolls, thus obtaining a laser-textured roll. The texturing point height is 0.012 mm, the texturing point diameter is 0.015 mm, and the texturing point density is 18 points / mm². 2 The convexity of the work rolls in the aluminum foil roughing mill and intermediate rolling mill, as well as the texturing work rolls in the aluminum foil finishing mill, is 0.04 mm.

[0101] 2. Adjustment of the lubrication system

[0102] The base oil for the first rolling oil is No. 80 base oil, and the mass percentage of lauric acid in the first rolling oil is controlled at 7.5 wt%. The base oil for the second rolling oil is No. 80 base oil, and the mass percentage of lauric acid in the second rolling oil is controlled at 7.0 wt%.

[0103] The temperature of the first rolling oil is controlled at 40℃, and the spraying rate is 1200L / min. The temperature of the second rolling oil is controlled at 50℃, and the spraying rate is 800L / min.

[0104] 3. Rolling of battery aluminum foil

[0105] The aluminum foil blank has a thickness of 0.30 mm, a tensile strength of 145 MPa, a crown of 0.1%, a thickness difference of 0.80%, and no obvious shape defects upon uncoiling. An 1850 mm series battery foil rolling mill was used, and the width of the aluminum foil blank was 1550 mm.

[0106] The specific preparation method of battery aluminum foil is as follows:

[0107] (1) Under the condition of the first rolling oil, the aluminum foil blank is rough rolled to reduce its thickness to 0.045 mm. Then, the rough-rolled aluminum foil blank is subjected to intermediate rolling to obtain an aluminum foil intermediate with a thickness of 0.012 mm. The tension setting range for the rough rolling and intermediate rolling processes is 30 kg / mm. 2 The specific tension is set according to the principle that "the tension on the exit side is about 70% of the tension on the inlet side", and the rolling speed of roughing and intermediate rolling is controlled at 600m / min.

[0108] (2) The laser texturing roller is preheated, and then the aluminum foil intermediate is subjected to a second rolling thinning and roughening treatment using a second rolling oil to obtain a surface-roughened aluminum foil. The tension setting range for the second rolling thinning treatment is 30 kg / mm. 2 The specific tension is set according to the principle that "the tension on the exit side is about 70% of the tension on the inlet side", and the rolling speed is controlled at 500m / min.

[0109] (3) Within 48 hours, the roughened aluminum foil is transferred to a two-roll corona treatment machine for corona treatment. The power of the corona treatment machine is 40kW, and the corona power is set to 30kW. The corona treatment speed is controlled at 120m / min. The specific corona treatment speed is adjusted according to the thickness of the incoming material, the shape of the plate, the level of oil, the temperature, and the dyne value ≥34 tested 8 hours after corona treatment. After corona treatment, battery aluminum foil is obtained.

[0110] The peel strength of the battery aluminum foil was measured using a universal testing machine (Instron 5540) at a peel rate of 300 mm / min. The peel strength was 3.11 N / cm for the uncoated battery aluminum foil and 4.72 N / cm for the coated battery aluminum foil.

[0111] Comparative Example 1

[0112] The difference between Comparative Example 1 and Example 1 is that the work rolls in the aluminum foil finishing mill were not roughened; instead, smooth-surfaced work rolls were used for the second rolling thinning and roughening treatment. Furthermore, the corona treatment power was set to 25kW based on the main power (i.e., the main unit corresponding to the corona roller discharge), and the corona speed was controlled at 200m / min. For uncoated battery aluminum foil, the peel strength was 0.08 N / cm; for coated battery aluminum foil, the peel strength was 3.24 N / cm.

[0113] Comparative Example 2

[0114] The difference between Comparative Example 2 and Example 1 is that the second rolling thinning and roughening treatments were performed without adding the second rolling oil.

[0115] The peel strength of the battery aluminum foil obtained in Comparative Example 2 was tested using the same test method as in Example 1. The peel strength of the uncoated battery aluminum foil was 0.11 N / cm; the peel strength of the coated battery aluminum foil was 3.47 N / cm.

[0116] As can be seen from the above test results, compared with Example 1, Comparative Example 1, which did not undergo surface roughening treatment, showed a significant decrease in peel strength and poor adhesion. Comparative Example 2, which did not add the second rolling oil, could not remove the debris and aluminum powder generated during the rolling process in time, resulting in the problem of foreign matter being pressed in, which affected the surface quality of the battery aluminum foil, and therefore its peel strength was also relatively low.

[0117] Figure 1 and Figure 2 The images shown are scanning electron microscope (SEM) images of the battery aluminum foils obtained in Example 1 and Comparative Example 1, respectively. It can be seen that the battery aluminum foil of Example 1 has surface embossed patterns of specific size and density, which can improve the adhesion strength between the battery aluminum foil and the electrode film. When used as a current collector in a battery, it can improve the conductivity and thermal shock resistance of the interface between the current collector and the electrode film material, thereby improving the cycle life and safety performance of the battery. In contrast, the surface of the battery aluminum foil in Comparative Example 1 is relatively smooth, resulting in poor adhesion.

[0118] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0119] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing battery aluminum foil, characterized in that, Includes the following steps: S10. A first rolling thinning treatment is performed on the aluminum foil billet using a first rolling oil to prepare an aluminum foil intermediate with a thickness of 0.021 mm to 0.023 mm. The first rolling thinning treatment includes rough rolling and intermediate rolling. The first rolling oil includes base oil and lubricating additives, and the mass percentage of the lubricating additives is 6.5 wt% to 8.0 wt% based on the total mass of the first rolling oil. S20. The aluminum foil intermediate is simultaneously subjected to a second rolling thinning treatment and a surface roughening treatment using a second rolling oil to prepare a surface-roughened aluminum foil with a thickness of 0.012 mm to 0.013 mm. Step S20 is performed using a texturing work roll. The surface of the texturing work roll includes multiple raised texturing points, the height of which is 0.002 mm to 0.02 mm; the outer diameter of which is 0.005 mm to 0.5 mm; and the density of which is 5 points / mm. 2 ~50 pieces / mm 2 The rolling speed for the second thinning process is 400 m / min to 600 m / min. S30. The surface roughened aluminum foil is subjected to corona treatment to prepare the battery aluminum foil; in the corona treatment, the corona power is 28 kW~32 kW and the corona velocity is 80 m / min~160 m / min.

2. The method for preparing battery aluminum foil as described in claim 1, characterized in that, The second rolling oil comprises base oil and lubricating additives, wherein the mass percentage of the lubricating additives is 6.0 wt% to 7.5 wt% based on the total mass of the second rolling oil.

3. The method for preparing battery aluminum foil as described in claim 2, characterized in that, The preparation method satisfies at least one of the conditions in (1) to (4): (1) The base oil of the first rolling oil includes No. 80 base oil; (2) The lubricating additives in the first rolling oil include lauric acid; (3) The base oil of the second rolling oil includes No. 80 base oil; (4) The lubricating additives of the second rolling oil include lauric acid.

4. The method for preparing battery aluminum foil as described in claim 2, characterized in that, The preparation method satisfies at least one of the conditions in (5) to (8): (5) The temperature of the first rolling oil is 40 ℃~45 ℃; (6) The temperature of the second rolling oil is 45 ℃~50 ℃; (7) The spray rate of the first rolling oil is 1100 L / min to 1500 L / min; (8) The spray rate of the second rolling oil is 700 L / min to 900 L / min.

5. The method for preparing battery aluminum foil according to any one of claims 1 to 4, characterized in that, The rolling speed for the first thinning process is 500 m / min to 700 m / min.

6. The method for preparing battery aluminum foil according to any one of claims 1 to 4, characterized in that, Step S10 includes the following steps: S101. The aluminum foil blank is subjected to rough rolling treatment using the first rolling oil to reduce the thickness of the aluminum foil blank to 0.045 mm to 0.050 mm. S102. The aluminum foil blank after rough rolling is subjected to intermediate rolling treatment using the first rolling oil to prepare the aluminum foil intermediate with a thickness of 0.021 mm to 0.023 mm.

7. The method for preparing battery aluminum foil according to any one of claims 1 to 4, characterized in that, Step S10 is performed using a work roller with a smooth surface.

8. The method for preparing battery aluminum foil according to any one of claims 1 to 4, characterized in that, The convexity of the texturing work roller is 20% to 60%.

9. A battery aluminum foil, characterized in that, The aluminum foil is prepared by the method described in any one of claims 1 to 8.

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