Process for producing aluminum foil for high-strength double-light 8-micron battery by using high-concentration additive
By using high-concentration additive rolling oil and a specific combination of rollers in aluminum foil production, the rolling and sheet shape control were optimized, solving the problems of "soft bars" and poor sheet shape in the production of ultra-thin high-strength aluminum foil, and achieving high stability and high yield in production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-15
- Publication Date
- 2026-03-13
AI Technical Summary
In the production of 8μm ultrathin high-strength aluminum foil, the "soft bar" defect and poor plate shape problem that occur during winding lead to poor production stability and low yield, which cannot meet the quality requirements of high-end digital batteries.
A rolling oil system with high concentrations of esters and alcohols, combined with work rolls and support rolls of specific crown, and low-hardness exit flattening rolls are used to optimize lubrication and shape control during the rolling process. The surface quality of the aluminum foil is improved through slitting and corona treatment.
It has achieved stable production with high quality and high yield, significantly improving the production stability and yield of ultra-thin, high-strength 8μm battery aluminum foil. The plate shape control accuracy has reached over 98%, and the yield has reached over 70%, meeting the current collector material requirements of high-end digital batteries.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of non-ferrous metal processing technology, and relates to the rolling production of aluminum foil, and particularly to a process for producing high-strength double-sided 8µm aluminum foil for batteries using a high concentration of additives. Background Technology
[0002] As consumer electronics products (such as smartphones, laptops, wearable devices, and drones) evolve towards thinner, lighter designs and longer battery life, higher demands are being placed on the energy density and volume of their core power source, lithium-ion batteries. As a key material for the positive electrode current collector in lithium-ion batteries, battery aluminum foil is evolving towards ultra-thin and high-strength designs. Among them, ultra-thin, high-strength dual-photovoltaic battery aluminum foil with a thickness of 8μm can significantly reduce battery weight, improve internal space utilization, and increase energy density, and has become a mainstream and cutting-edge material in the high-end digital battery field.
[0003] However, the extremely high technical difficulty in the mass production of 8μm ultrathin high-strength aluminum foil poses a severe challenge to traditional rolling processes. Due to the extremely thin thickness of the foil, its physical properties, deformation behavior, and mechanical properties are highly sensitive to fluctuations in production process parameters, resulting in poor production stability and low yield. Among these, the "soft bar" defect that occurs during winding and the poor shape of the finished product are the two most prominent and fatal technical bottlenecks restricting the mass production of high-quality digital battery aluminum foil.
[0004] The "soft bar" defect is a concentrated manifestation of localized poor plate shape. This area is subjected to greater local pressure, which not only seriously affects the product appearance, but also damages the conductivity uniformity and mechanical consistency of the foil. This leads to risks such as strip breakage and edge curling during subsequent battery electrode coating and slitting processes, making it impossible to meet the stringent requirements of high-speed automated battery production lines.
[0005] Flatness is a core indicator for measuring foil flatness, and controlling it for 8μm ultrathin foil is a recognized challenge in the industry. During the rolling process, even slight changes in the thermal crown, roll shape, and cooling and lubrication conditions of the rolls can alter the roll gap shape, which is sensitively reflected in the flatness, leading to defects such as loose ribs, tight edges, bubbles, and loose centers in the aluminum foil. Poor flatness (such as center waviness, edge waviness, and rib waviness) can cause the foil to run off-center and wrinkle on the battery electrode coating machine, resulting in uneven coating thickness, scratching of the coating head, and causing large-scale production stoppages and quality incidents. At the same time, poor flatness can also affect the dimensional accuracy of the stamped tabs, thereby impairing the electrochemical and safety performance of the battery.
[0006] In summary, effectively suppressing and eliminating the "soft rod" defect during the production of ultra-thin, high-strength 8μm digital battery aluminum foil, and achieving high-precision and stable control of its shape, has become a key core technology that urgently needs to be overcome in the industry. Existing conventional aluminum foil production processes and equipment can no longer meet the quality requirements of this ultra-thin, high-strength battery aluminum foil, necessitating the development of a completely new and systematic production technology. Summary of the Invention
[0007] In view of the problems of difficult plate shape control and easy occurrence of "soft bars" in the production of ultra-thin aluminum foil, the purpose of this invention is to provide a process for producing high-strength double-luminous 8um aluminum foil for batteries with high concentration of additives.
[0008] Technical solution
[0009] A process for producing high-strength, dual-light 8µm battery aluminum foil using high-concentration additives includes the following steps:
[0010] S1. Rough and Intermediate Rolling: The battery foil blank is rolled to a single zero aluminum foil thickness through multiple passes on a roughing mill. The rolling oil used is a mixture of 80# base oil, 5-6% alcohol additives (by mass of the rolling oil), and 25-30% ester additives (by mass of the rolling oil), with a viscosity of 2.25-2.35 mm. 2 / s;
[0011] S2. Finishing Single-Sheet Rolling: Single-sheet aluminum foil is rolled and trimmed in a single pass on a finishing mill to obtain a single sheet of aluminum foil with an intermediate thickness. The rolling oil used is a mixture of 80# base oil, 15-18% ester additives by weight of the total rolling oil, and 4-5% alcohol additives by weight of the total rolling oil, with a viscosity of 2.20-2.30 mm. 2 / s;
[0012] S3, Finishing pass: The single aluminum foil is finished on the finishing mill to obtain a finished aluminum foil with a thickness of 8μm. The rolling oil is the same as in step S2. The exit flattening roll must be replaced with a soft roll with a Shore hardness of 75-80 HS, preferably a nitrile rubber roll.
[0013] S4. Slitting and Precision Cutting: After slitting the precision rolled aluminum foil, it is then precision cut into the specifications required by the user, and at the same time, corona treatment is performed to obtain the finished lithium battery foil.
[0014] In a preferred embodiment of the present invention, in step S1, the battery foil raw material is 1100 alloy in H18 temper, with a tensile strength ≥200 N / mm². 2 The elongation is ≥3.0%; furthermore, the thickness of the battery foil raw material is 0.21~0.24mm±3%, preferably 0.21mm.
[0015] In a preferred embodiment of the present invention, in step S1, the oil pressure of the rolling oil is 8.0±0.5 bar, and the flow rate is 50-60%.
[0016] In a preferred embodiment of the present invention, in step S1, the rolling passes are: 0.21mm → 0.10mm → 0.044mm → 0.020mm, wherein: the roughness Ra of the work rolls used in the first and second passes (rough rolling) is 0.24±0.01μm, and the radial crown Cr is 0.02~0.04mm; the roughness Ra of the work rolls used in the third pass (intermediate rolling) is 0.13~0.15μm, and the radial crown Cr is 0.02~0.04mm;
[0017] The support rolls used in the above passes have a surface roughness Ra of 0.6±0.03μm and a radial crown Cr of 0.01~0.02mm, preferably 0.01mm (10‰); the target profile curve value for the roughing and intermediate rolling passes is set to ≤12 N / mm. 2 .
[0018] In a preferred embodiment of the present invention, step S2 is a single pass before the finished product. Taking the rolling of 0.020mm aluminum foil to 0.012mm as an example, it specifically includes: the roughness Ra of the work roll is 0.10±0.005μm, and the radial convexity Cr is 90~110‰ (increasing with the increase of the material width); the roughness Ra of the support roll is 0.6±0.03μm, and the radial convexity Cr is 0.01~0.02mm.
[0019] Furthermore, in step S2, the target plate shape curve value is set to ≤12 N / mm. 2 The rolling inlet tension is set to 50~60 N / mm. 2 .
[0020] In a preferred embodiment of the present invention, in step S2, the oil pressure of the rolling oil is 6.0±0.5 bar, and the flow rate is 50~60%.
[0021] In a preferred embodiment of the present invention, step S3 is the finished product pass, which rolls the 0.012mm aluminum foil to 0.008mm, specifically including:
[0022] The working rolls used have a surface roughness Ra of 0.07~0.09μm and a radial crown Cr of 70~80‰.
[0023] The support roller used has a surface roughness Ra of 0.6±0.03μm and a radial crown Cr of 0.01mm (10‰).
[0024] The target plate shape curve value is set to 12~15 N / mm. 2 .
[0025] The rolling oil used has a pressure of 4~5 bar and a flow rate of ≤40%.
[0026] In a preferred embodiment of the present invention, in step S4:
[0027] During slitting, a hot air knife is installed at the inlet guide roller to blow hot air at 200~-250℃ onto the upper and lower surfaces of the aluminum foil to remove residual oil.
[0028] During precision cutting, corona treatment is used to further clean the aluminum foil surface. The corona power is 8~15kW to increase the surface wetting tension to ≥32 dyn.
[0029] In a preferred embodiment of the present invention, the alcohol additive is mainly C12 lauryl alcohol; the ester additive is mainly C12-14 butyl stearate.
[0030] In the process described in this invention, the use of rolling oil with high concentrations of ester and alcohol additives in the key passes (especially steps S2 and S3) significantly improves the lubrication effect during rolling, ensuring the uniformity of metal deformation and fundamentally reducing local shape defects caused by uneven deformation. Simultaneously, the specific crown of the work rolls in conjunction with the support rolls, along with the use of lower-hardness exit flattening rollers in the finishing pass, works together to achieve precise shape control and smooth winding, effectively eliminating the "soft bar" defect.
[0031] Beneficial effects
[0032] This invention achieves stable production with high quality and high yield by employing a rolling oil system with high-concentration additives and synergistically optimizing roll crown, sheet shape control strategies, and winding and flattening devices. It significantly improves the stability and yield of ultra-thin, high-strength 8μm battery aluminum foil production, achieving an overall yield of over 70% and an effective cut width of 80-85%. Through the synergistic combination of high-concentration additives in the rolling oil and specific process parameters, excellent sheet shape control is achieved, with the actual sheet shape matching the target sheet shape in passes 1-4 reaching over 98%, and the finished pass matching reaching over 95%. It effectively eliminates the "soft bar" defect during the winding process, resulting in good winding quality and a clean, flat product surface, meeting the stringent requirements of high-end digital batteries for current collector materials. The production process is highly controllable, providing reliable technical support for high-quality, high-volume production of ultra-thin digital battery aluminum foil. Detailed Implementation
[0033] The present invention will be described in detail below with reference to embodiments to enable those skilled in the art to better understand the present invention, but the present invention is not limited to the following embodiments. Unless otherwise specified, the raw materials and equipment involved in the embodiments are all conventional commercially available products in the art.
[0034] The ester additive (STE6, whose main component is C12-14 butyl stearate) and alcohol additive (STE12, whose main component is C12 lauryl alcohol) used in this invention were both purchased from Shijiazhuang Xintai Special Oil Co., Ltd.
[0035] Example 1
[0036] This embodiment produces high-strength, dual-color 8μm×(560+320) mm battery aluminum foil. The finished product quality requirements are: thickness 8±0.24μm, tensile strength ≥260 N / mm². 2 Elongation ≥3.0%, surface wetting tension ≥32 dyn; Plate type Grade A (2-meter roll gap, 0.8 kg / mm²) 2 The collapse under tension is ≤5 mm; the surface is clean with no color difference, no visible streaks or bubbles; the number of pinholes (diameter <0.1 mm) is ≤50 / m. 2 .
[0037] The production process steps are as follows:
[0038] Step 1: Roughing and Intermediate Rolling
[0039] Made of 1100H18 alloy, with raw material dimensions of 0.21mm × 1020mm and tensile strength of 200±5 N / mm². 2 Elongation rate 4.5%.
[0040] Rolling passes: 0.21mm→0.10mm→0.044mm→0.020mm.
[0041] The roughness of the first and second passes of the work roll is Ra 0.24μm, and the crown is Cr 0.02mm (20‰); the roughness of the third pass of the work roll is Ra 0.13μm, and the crown is Cr 0.02mm (20‰).
[0042] The support roller has a surface roughness Ra of 0.6 μm and a crown Cr of 0.01 mm (10‰).
[0043] Target plate shape curve value: 12 N / mm².
[0044] Rolling oil: Measured viscosity 2.29 mm 2 / s, containing 29% ester additives (STE6) and 5.0% alcohol additives (STE12).
[0045] Rolling parameters: hydraulic pressure 8.0 bar, flow rate 50%.
[0046] The plate shape is stable during the production process, the actual plate shape is less than 3% of the target plate shape tolerance, there is no broken strip, and the surface quality is good.
[0047] Step 2, Finishing single-sheet rolling pass (4th pass):
[0048] Roll the 0.020mm single zero aluminum foil obtained in step one to 0.012mm.
[0049] The surface roughness Ra of the working roll is 0.10 μm, and the crown Cr is 0.10 mm (100‰).
[0050] The support roller is the same as in step one.
[0051] Target plate profile curve value: 12 N / mm 2 .
[0052] Rolling oil: Measured viscosity 2.23 mm 2 / s, containing 16.8% ester additives and 3.5% alcohol additives.
[0053] Rolling parameters: hydraulic pressure 6.0 bar, flow rate 50%; inlet tension 50-60 N / mm 2 Speed: 650-700 m / min.
[0054] The resulting 0.012mm aluminum foil sheet exhibits stable shape (sigma <3%) and a tensile strength of 278 N / mm². 2 Elongation 4.25%, pinhole count <2 / mm 2 The sag of the offline board type 8N is ≤4mm.
[0055] Step 3, Finishing Rolling Pass (5th Pass):
[0056] The 0.012mm aluminum foil obtained in step two is rolled into a 0.008mm finished product.
[0057] The surface roughness Ra of the working roll is 0.08μm, and the crown Cr is 0.076mm (76‰).
[0058] The support roller is the same as in step two.
[0059] Target plate profile curve value: 12 N / mm 2 .
[0060] The export flattening rollers were replaced with nitrile rubber rollers with a hardness of 76 HS.
[0061] The rolling oil parameters are the same as in step two: oil pressure 4.5 bar, flow rate 40%, and speed 350-400 m / min.
[0062] The resulting 8μm finished aluminum foil exhibits stable sheet shape (sigma <6%), no soft ridges on the winding surface, tensile strength of 283 N / mm², elongation of 4.2%, and pinhole count <20 / m. 2 The slump of the offline board type 8N is ≤5mm.
[0063] Step 4: Post-processing:
[0064] During slitting, a 250℃ hot air knife is used to remove residual oil from the surface. During precision cutting, corona treatment is applied (8.8kW each for upper and lower sections), with a precision cutting speed of 90-120 m / min. The surface wetting tension of the finished product reaches 33 dyn, and the precision cutting yield is 88%.
[0065] Example 2
[0066] This embodiment produces high-strength, double-sided 8μm × (610+420) mm battery aluminum foil, with finished product quality requirements the same as in Example 1. The raw material specifications are 0.21mm × 1200mm.
[0067] The production process and parameters are basically the same as in Example 1, with the main differences as follows:
[0068] Step 1: For the first two passes, the crown of the work rolls is 0.030 mm (20‰), and for the third pass, it is 0.02 mm (30‰). The rolling oil viscosity is 2.31 mm. 2 / s, ester content 30%, alcohol content 4.8%.
[0069] Step 2: Work roll crown Cr 0.11mm (110‰). Rolling oil viscosity 2.25mm. 2 / s, ester content 16.1%, alcohol content 4.0%.
[0070] Step 3: Since the material width is 1200mm (width), the crown of the work roll (Cr) is selected as 0.080mm (80‰). Other steps are the same as in Example 1.
[0071] The final product met the performance standards, with an offline 8N plate thickness of 5.4mm and a precision cutting yield of 87%.
[0072] Comparative Example 1
[0073] To verify the effectiveness of the key technology of this invention (high-concentration additives and soft rubber rollers), conventional low-concentration additive rolling oil and hard rubber rollers were compared.
[0074] The 0.012mm×1000mm aluminum foil produced in step two of Example 1 was used as the raw material.
[0075] Step 3 (Finished Product Pass):
[0076] The working roll parameters are the same as in Example 1 (Ra 0.08μm, Cr 76‰).
[0077] The export flattening rollers use rubber rollers with a hardness of 90 HS (not replaced with soft rubber rollers).
[0078] Rolling oil: viscosity 2.05 mm2 / s, ester additive content 10.2%, alcohol additive content 4.8%.
[0079] Other rolling parameters (oil pressure, flow rate, speed, etc.) are the same as in step three of Example 1.
[0080] Results: Severe "soft bars" and "dead bars" appeared on the winding surface, resulting in unstable sheet shape, exhibiting a W-shape (loose in the middle and loose in the ribs), with sheet shape tolerance sigma fluctuating between 12-18%. After replacing with 76 HS soft rubber rollers, the winding surface improved, but the sheet shape remained poor, with ribs loose and moderately tight. The final offline sheet shape had a maximum 8N collapse of 12mm, with cross-bubbling, and could only cut products up to 320mm wide, resulting in a cuttable width yield of approximately 35%.
[0081] Comparative Example 2
[0082] Using a wider range of raw materials for comparison further clarifies the issue.
[0083] The 0.012mm×1170mm aluminum foil produced in step two of Example 1 was used as the raw material.
[0084] Step 3 (Finished Product Pass):
[0085] The crown of the working roller is adjusted to 80‰ according to the material width.
[0086] Using a rubber roller with a hardness of 90 HS initially resulted in severe softness and wrinkling during production.
[0087] After replacing it with a 76 HS soft rubber roller, the winding surface improved, but the sheet shape tolerance sigma still fluctuated between 12-15%, and there were issues with tight edges and loose ribs.
[0088] The rolling oil was the same as that in Comparative Example 1 (low concentration additive).
[0089] Results: The production process was unstable. The maximum collapse of the final offline board type 8N was 15mm, with obvious bubble formation. Only 500mm wide products could be cut, and the yield of cut width was about 40%.
[0090] The results are shown in the table below:
[0091]
[0092] The comparison results above show that by using a high-concentration rolling oil system and combining it with low-hardness nitrile rubber flattening rollers for the finished product passes, the present invention can significantly improve the accuracy of sheet shape control and winding quality, greatly increase the yield of ultra-thin products, and solve the technical bottlenecks that traditional processes cannot overcome.
[0093] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A process for producing high-strength, dual-light 8µm battery aluminum foil using high-concentration additives, characterized in that, Includes the following steps: S1. Roughing and Intermediate Rolling: The battery foil blank is rolled to a single zero aluminum foil thickness through multiple passes on a roughing mill. The rolling oil used is a mixture of 80# base oil, 5-6% alcohol additives (by mass of the rolling oil), and 20-25% ester additives (by mass of the rolling oil), with a viscosity of 2.25-2.35 mm. 2 / s; S2. Finishing Single-Sheet Rolling: Single-sheet aluminum foil is rolled and trimmed in a single pass on a finishing mill to obtain a single sheet of aluminum foil with an intermediate thickness. The rolling oil used is a mixture of 80# base oil, 15-18% ester additives and 4-5% alcohol additives by mass of the total rolling oil, with a viscosity of 2.20-2.30 mm. 2 / s; The export flattening rollers are ordinary rubber rollers with a Shore hardness of 85-90 HS; S3, Finishing pass: The single aluminum foil is finished on the finishing mill to obtain a finished aluminum foil with a thickness of 8μm. The rolling oil is the same as in step S2. The exit flattening roll is a soft roll with a Shore hardness of 75~80HS, preferably a nitrile rubber roll. S4. Slitting and precision cutting: The finished aluminum foil is slitting and precision cutting and then subjected to corona treatment to obtain the finished lithium battery foil.
2. The process for producing high-strength dual-light 8µm battery aluminum foil using high-concentration additives according to claim 1, characterized in that: In step S1, the battery foil raw material is 1100 alloy in H18 temper, with a tensile strength ≥200 N / mm. 2 The elongation is ≥3.0%; the thickness is 0.21~0.24mm±3%, preferably 0.21mm.
3. The process for producing high-strength, dual-light 8µm battery aluminum foil using high-concentration additives according to claim 1, characterized in that: In step S1, the oil pressure of the rolling oil is 8.0±0.5 bar, and the flow rate is 50~60%.
4. The process for producing high-strength, dual-light 8µm battery aluminum foil using high-concentration additives according to claim 1, characterized in that, In step S1, the rolling passes are: 0.21mm→0.10mm→0.044mm→0.020mm, wherein: the roughness Ra of the work rolls used in the first and second passes is 0.24±0.012μm, and the radial crown Cr is 0.02~0.04mm; the roughness Ra of the work rolls used in the third pass is 0.13~0.15μm, and the radial crown Cr is 0.02~0.04mm.
5. The process for producing high-strength, dual-light 8µm battery aluminum foil using high-concentration additives according to claim 1, characterized in that: In step S1, the target plate shape curve value for each pass is set to ≤12 N / mm. 2 .
6. The process for producing high-strength, dual-light 8µm battery aluminum foil using high-concentration additives according to claim 1, characterized in that: In step S2, the target plate shape curve value is set to ≤12 N / mm. 2 The rolling inlet tension is set to 50~60 N / mm. 2 .
7. The process for producing high-strength, dual-light 8µm battery aluminum foil using high-concentration additives according to claim 1, characterized in that: In step S2, the oil pressure of the rolling oil is 6.0±0.5 bar, and the flow rate is 50~60%.
8. The process for producing high-strength, dual-light 8µm battery aluminum foil using high-concentration additives according to claim 1, characterized in that: In step S3, the working roll has a surface roughness Ra of 0.07-0.09 μm and a radial crown Cr of 70-80‰; the support roll has a surface roughness Ra of 0.6±0.03 μm and a radial crown Cr of 0.01 mm; the target plate profile curve value is set to 15 N / mm. 2 The rolling oil used has a pressure of 4-5 bar and a flow rate of ≤40%.
9. The process for producing high-strength, dual-light 8µm battery aluminum foil using high-concentration additives according to claim 1, characterized in that, In step S4: During slitting, a hot air knife is installed at the inlet guide roller to blow hot air at 200-250℃ onto the upper and lower surfaces of the aluminum foil to remove residual oil; during precision cutting, corona treatment is used to further clean the surface of the aluminum foil, with a corona power of 8-15kW, to increase the surface wetting tension to ≥32dyn.
10. The process for producing high-strength, dual-light 8µm battery aluminum foil using high-concentration additives according to claim 1, characterized in that: The alcohol additive is mainly C12 lauryl alcohol; the ester additive is mainly C12-14 butyl stearate.