Method for eliminating the white space recess of carbon-coated aluminum foil and equipment thereof

Abstract

This invention discloses a method and apparatus for eliminating blank areas and depressions in carbon-coated aluminum foil, belonging to the field of lithium-ion battery current collector technology. The method includes: providing a ceramic-coated base film, comprising a polymer base film and a ceramic coating coated thereon; during the carbon-coating process of the aluminum foil, simultaneously winding the ceramic-coated base film and the coated aluminum foil, so that the ceramic coating covers the blank areas of the carbon-coated aluminum foil, thereby filling the thickness difference between the blank areas and the carbon-coated areas. This invention, by filling the thickness difference of the blank areas with the ceramic-coated base film during winding, eliminates air introduction and compression deformation at the source, effectively preventing the formation of blank areas and depressions; simultaneously, the ceramic-coated base film can be recycled and reused after separation at the battery cell end, offering good economic benefits. This invention also discloses apparatus for implementing this method.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery current collector technology, and specifically relates to a method and equipment for eliminating white depressions in carbon-coated aluminum foil. Background Technology

[0002] With the development of the new energy vehicle sector, companies in the industry are placing increasingly higher demands on power vehicle batteries. Lithium batteries are widely used due to their advantages such as high cycle performance, high safety, and zero pollution. As the lithium-ion battery industry develops, higher requirements are being placed on the quality and process efficiency of the positive electrode sheet. The issue of blanking / sinking is one of the difficulties affecting the quality and process efficiency of the positive electrode sheet.

[0003] Carbon-coated aluminum foil consists of a 2-4 μm thick lithium-ion battery positive electrode current collector coated onto a plain aluminum foil base. The uncoated area in the center of the carbon-coated aluminum foil serves as the lithium battery tab area. During the processing of carbon-coated aluminum foil, the increasing number of winding layers leads to a growing thickness difference between the uncoated and carbon-coated areas. A single-sided coating thickness is 1-2 μm, resulting in a total thickness difference of 2-4 μm after double-sided coating. During winding, air is introduced through interlayer gaps. This air cannot escape quickly enough during the dense winding process, causing deformation of the uncoated aluminum foil area. Once deformation occurs in the bottom uncoated area, it continues to affect the uncoated areas in subsequent windings, ultimately resulting in indentations and deformation marks in the uncoated areas of the entire roll of carbon-coated aluminum foil.

[0004] For a long time, in the large-scale production of lithium-ion batteries, the recessed areas have been one of the major challenges in the processing of carbon-coated aluminum foil. Existing technologies mostly alleviate the recessed area problem by adjusting process parameters such as winding tension and controlling winding speed, but they fail to eliminate the air introduction caused by thickness differences at the root, and the effect is limited. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for eliminating blanking depressions in carbon-coated aluminum foil. This method can eliminate the thickness difference between the blanking area and the carbon-coated area from the source, avoid the introduction of air, and thus effectively prevent the formation of blanking depressions. At the same time, it realizes the recycling of filling materials, which has good economic benefits.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: This invention provides a method for eliminating white recesses in carbon-coated aluminum foil, comprising the following steps: S1. Provide a ceramic-coated base film, wherein the ceramic-coated base film includes a polymer base film and a ceramic coating coated thereon; S2. During the carbon-coated aluminum foil coating process, the ceramic base film and the coated carbon-coated aluminum foil are wound up simultaneously, so that the ceramic coating covers the blank area of ​​the carbon-coated aluminum foil to fill the thickness difference between the blank area and the carbon-coated area.

[0007] Furthermore, the method for eliminating the blanking depressions of carbon-coated aluminum foil also includes the step of preparing the ceramic-coated base film: coating a ceramic slurry onto a polymer base film, drying and curing it to form a ceramic coating, thereby obtaining the ceramic-coated base film.

[0008] Furthermore, the method for eliminating the blanking depressions on the carbon-coated aluminum foil also includes: in the subsequent cell manufacturing process, separating the ceramic-coated base film from the carbon-coated aluminum foil, and recycling and reusing the separated ceramic-coated base film.

[0009] Furthermore, the ratio of the thickness of the ceramic coating to the thickness of the single-sided coating of the carbon-coated aluminum foil is 0.8~1.2:1.

[0010] Furthermore, the width of the ceramic coating is less than or equal to the width of the blank area of ​​the carbon-coated aluminum foil, and is not less than 90% of the width of the blank area.

[0011] Furthermore, the width of the ceramic coating is 1-3 mm narrower than the width of the blank area of ​​the carbon-coated aluminum foil.

[0012] Furthermore, when reused, the service life is determined by monitoring the change in the thickness of the ceramic coating on the ceramic-coated base film during reuse: when the difference between the thickness of the ceramic coating and the thickness of the single-sided coating of the carbon-coated aluminum foil exceeds 0.5 μm, the use is stopped and a new ceramic-coated base film is replaced.

[0013] Furthermore, the polymer base film is a polyethylene film, a polypropylene film, a polyacrylonitrile film, or a polyvinyl chloride film; the ceramic coating is formed by applying an alumina ceramic slurry, a boehmite ceramic slurry, or a zirconia ceramic slurry.

[0014] The present invention also provides an apparatus for eliminating blanking depressions in carbon-coated aluminum foil to implement the method described in any of the above claims, comprising: The first coating unit is used to coat a carbon-coated conductive paste onto an aluminum foil substrate to form a carbon-coated aluminum foil. The first unwinding unit is used to unwind ceramic-coated films. The first winding unit is used to simultaneously wind up the carbon-coated aluminum foil and the ceramic-coated base film, so that the ceramic coating on the ceramic-coated base film covers the blank area of ​​the carbon-coated aluminum foil. And a guide roller disposed between the first coating unit and the first winding unit, used to guide the carbon-coated aluminum foil and the ceramic-coated base film to bond together.

[0015] Furthermore, the device also includes a cell-end separation unit, the cell-end separation unit comprising: The second unwinding unit is used to unwind the composite roll of carbon-coated aluminum foil and ceramic-coated base film that has been simultaneously wound up; The second coating unit is used to coat the positive electrode slurry in the carbon coating area of ​​the carbon-coated aluminum foil; The dual-path winding unit includes an upper winding roller and a lower winding roller. The upper winding roller is used to wind up the separated ceramic-coated base film, and the lower winding roller is used to wind up the carbon-coated aluminum foil after the positive electrode slurry is applied.

[0016] Furthermore, the device also includes a CCD vision alignment system and a lateral correction device. The CCD vision alignment system is used to identify the edges of the aluminum foil and the ceramic coating in real time, and the lateral correction device is used to automatically adjust the lateral position of the first unwinding unit according to the signal from the CCD vision alignment system.

[0017] Compared with the prior art, the beneficial technical effects of this invention are reflected in: 1. Elimination of Depressions: This invention achieves precise coverage of the blank areas by simultaneously winding the ceramic-coated base film and the carbon-coated aluminum foil. This fundamentally fills the thickness difference between the blank areas and the carbon-coated areas, avoiding air introduction and aluminum foil extrusion deformation, significantly reducing or even completely eliminating blank area depressions. Experiments show that the incidence of blank area depressions can be controlled below 10% using this method, with the preferred solution reaching 0%.

[0018] 2. Material recycling and good economic benefits: The ceramic base film can be naturally separated and recycled during the coating process of the positive electrode of the battery cell. After thickness monitoring, it can be reused multiple times (e.g., 5 times), which greatly reduces material costs and has good economic and environmental benefits.

[0019] 3. Simple equipment structure and low modification cost: Based on the existing coating machine and positive electrode coating machine, this invention only needs to add unwinding and rewinding units to achieve synchronous rewinding and separation recycling. The equipment modification cost is low and it is easy to promote and apply. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the winding interlayer structure for eliminating the white recesses in the carbon-coated aluminum foil in an embodiment of the present invention; Figure 2 This is a schematic diagram of the equipment structure for synchronous winding of carbon-coated aluminum foil in an embodiment of the present invention; Figure 3 This is a schematic diagram of the winding device structure at the cell end in an embodiment of the present invention; Figure 4 This is a schematic diagram of a partial matching structure between a ceramic-coated substrate film and a carbon-coated aluminum foil in an embodiment of the present invention.

[0021] In the diagram: 1-Ceramic-coated base film, 2-Roll, 3-Carbon-coated aluminum foil, 4-Ceramic layer, 5-Carbon coating layer, 6-Base film, 7-Aluminum foil, 8-First coating unit, 9-First unwinding unit, 10-First winding unit, 11-PE or PP film roll coated with ceramic layer, 12-Composite carbon-coated aluminum foil and ceramic-coated base film, 13-Guide roller, 14-Second unwinding unit, 15-Second coating unit, 16-Dual winding unit, 17-Lower winding roller, 18-Upper winding roller. Detailed Implementation

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0024] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0025] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] Example 1 A method for eliminating white indentations on carbon-coated aluminum foil includes the following steps: a. Mixing of carbon-coated conductive paste The carbon-coated conductive slurry was stirred at high speed using a double planetary mixing vessel A, then transferred to a sand mill and ground seven times until the fineness was ≤5μm, to obtain the finished carbon-coated conductive slurry.

[0027] Commercially available carbon-coated conductive pastes (such as Yuanyuan Technology's YY04 conductive paste, but not limited to this) are used. This paste is a commonly used material in the field of carbon-coated aluminum foil for lithium-ion batteries. This step can also be prepared by yourself according to conventional paste-making processes, including stirring and grinding to a fineness of ≤5μm.

[0028] b. Preparation of ceramic slurry The following raw materials were weighed in parts by weight: 12 parts alumina powder (average particle size D50 of 0.5 μm), 12 parts polyacrylic acid binder (solid content 25±2%, brand name Lubrizol 702, purchased from Lubrizol), 1 part dispersant (brand name TPG-621, purchased from Lubrizol), and 76 parts deionized water. The above raw materials were added to a double planetary mixing vessel B. The mixture was first stirred at 500 rpm for 10 minutes to wet the powder, and then stirred at 1200 rpm for 120 minutes to obtain a ceramic slurry. The viscosity of the slurry was measured using a rotational viscometer and controlled to be 200~500 mPa·s (25℃); the solid content was determined by gravimetric analysis and controlled to be 15%±1%.

[0029] c. Preparation of ceramic-coated films The ceramic slurry prepared in step 2 was transferred to the feed trough of a double-sided micro-grooved roller coater. The micro-grooved roller parameters were selected as follows: roller diameter 150 mm, line count 180 lines / inch, coating width 60 mm. A polyethylene (PE) base film (10 μm thick, 520 mm wide) was mounted on the unwinding shaft. The coater was started, and the coating parameters were set as follows: coating speed 120 m / min, micro-grooved roller speed to coating speed ratio 1.2:1, and drying temperature set in three stages: 80℃ (stage 1, length 4 m), 100℃ (stage 2, length 4 m), and 80℃ (stage 3, length 4 m). After coating, the ceramic coating dried and cured to obtain a ceramic base film. The coating thickness was measured using a micrometer, and the single-layer thickness of the ceramic coating was controlled to be 1.5 ± 0.2 μm. Referring to GB / T 2790-1995, the ceramic-coated film was cut into 25mm×200mm samples, and then attached to a stainless steel plate with double-sided tape. A 180° peel test was performed at a speed of 100 mm / min. The adhesion between the ceramic coating and the PE substrate was 12.5 N / m.

[0030] The prepared ceramic-coated film structure is as follows Figure 4 As shown, it includes a base film 6 and a ceramic layer 4 coated thereon. To clearly demonstrate the compatibility between the ceramic layer 4 and the carbon-coated aluminum foil, Figure 4 The relative positions of the carbon coating layer 5 and the aluminum foil 7 are also illustrated. The ceramic layer 4 is located in the center of the base film 6, and its width is slightly smaller than the width of the blank area of ​​the carbon-coated aluminum foil (58 mm in this embodiment, and the blank area is 60 mm wide). The thickness of the ceramic layer 4 is controlled at 1.5 ± 0.2 μm, which is basically consistent with the single-sided thickness of the carbon coating layer 5, ensuring that the ceramic layer 4 can accurately fill the thickness difference between the blank area and the carbon coating area during winding.

[0031] It should be noted that the ceramic-coated base film of the present invention is not limited to the above preparation method, and commercially available similar products can also be used directly, as long as the thickness and width of its ceramic coating match the blank area of ​​the carbon-coated aluminum foil.

[0032] d. Simultaneous winding of carbon-coated aluminum foil The carbon-coated conductive paste prepared in step a is transferred to the feed tank of the gravure coating machine.

[0033] The structure of the synchronous winding equipment for the carbon-coated aluminum foil end used in this step is as follows: Figure 2 As shown, the equipment includes a first coating unit 8, a first unwinding unit 9, and a first winding unit 10. Its specific structure and working principle are as follows: First coating unit 8: Located on the far left of the equipment, it is the material receiving end of the carbon-coated aluminum foil, used to complete the coating process of carbon conductive paste and output the carbon-coated aluminum foil substrate to be rolled up.

[0034] First unwinding unit 9: Located in the middle of the equipment, it is used to load PE or PP film rolls 11 coated with ceramic layers, and can stably unwind the ceramic-coated base film to provide a substrate for subsequent synchronous lamination.

[0035] First winding unit 10: Located on the far right of the equipment, it is used to simultaneously wind up the carbon-coated aluminum foil and the ceramic-coated base film 12 after the alignment and lamination are completed, and finally obtain the finished carbon-coated aluminum foil roll that can eliminate blank depressions.

[0036] Guide roller structure: Two sets of guide rollers 13 are provided between the first coating unit 8 and the first winding unit 10 to guide the conveyor belt path of the carbon-coated aluminum foil, so that the carbon-coated aluminum foil is aligned and adhered to the ceramic base film output from the first unwinding unit 9, ensuring that the ceramic coating covers the blank area of ​​the carbon-coated aluminum foil and eliminating the blank depression.

[0037] The specific steps for this operation are as follows: (1) Position matching design: In this embodiment, the aluminum foil substrate is 520mm wide, and the blank area of ​​the carbon-coated aluminum foil is located in the center of the width direction, with a width of 60mm; the ceramic-coated base film prepared in step c is 520mm wide, and the ceramic coating is located in the center of the base film, with a width of 58mm, slightly smaller than the width of the blank area. Even if there are slight fluctuations in subsequent correction, it can be ensured that the ceramic coating falls completely within the blank area without overlapping with the carbon-coated area. At the same time, the 2mm gap has been verified by experiments to not affect the depression elimination effect (the wider blank area is not sensitive to gaps). (2) Initial calibration: Install the aluminum foil substrate on the first unwinding shaft and set the unwinding tension to 60 N. Install the ceramic-coated base film on the second unwinding shaft and set the unwinding tension to 60 N. Adjust the horizontal distance between the second and first unwinding shafts to 2.0 m. Adjust the lateral position of the second unwinding shaft by manually adjusting the lead screw (minimum adjustment amount 0.1 mm) to align the edge of the ceramic coating of the ceramic-coated base film with the edge of the blank area of ​​the aluminum foil. Start the coating machine at low speed (15 m / min) and use a stroboscope (frequency synchronized with the coating speed) to observe the overlap between the ceramic coating area and the blank area during operation. After confirming that the alignment accuracy meets the requirements, enter the automatic operation mode.

[0038] (3) Online automatic correction: When the coating machine is running normally (30 m / min), the CCD vision alignment system (resolution 0.1mm) identifies the edge of the aluminum foil and the edge of the ceramic coating of the ceramic base film in real time. When the offset exceeds the set tolerance (±1.0mm), the control system drives the lateral correction device (accuracy ±0.1mm) to automatically adjust the lateral position of the second unwinding shaft and correct the offset in real time.

[0039] (4) Tension matching: Control the unwinding tension difference between the first unwinding mechanism and the second unwinding mechanism to within ±5 N, so as to avoid relative slippage between the two during synchronous winding due to tension fluctuations.

[0040] (5) Synchronous winding: Coating parameters: Coating speed 80 m / min, drying temperature set in three stages: 90℃ (stage 1), 110℃ (stage 2), 90℃ (stage 3), winding tension 70 N. After coating, the carbon-coated aluminum foil and the ceramic-coated base film are wound synchronously, and the ceramic coating of the ceramic-coated base film fills the blank area of ​​the carbon-coated aluminum foil. After winding, the finished carbon-coated aluminum foil is obtained with a roll length of 1000m. The flatness of the end face of the roll is measured with calipers, and there is no obvious height difference between the blank area and the carbon-coated area. Alignment accuracy verification: During the winding process, 5 time points are randomly selected, and the overlap width between the ceramic coating and the blank area is measured with a CCD vision system. The coverage rate is calculated as (overlap width / blank area width) × 100%, and the average coverage rate is 98.5%.

[0041] After synchronous winding is completed, the winding interlayer structure is as follows: Figure 1 As shown, ceramic-coated base film 1 and carbon-coated aluminum foil 3 are stacked and wound onto roll 2.

[0042] e. Separation and Recycling The structure of the cell-end separation equipment used in this step is as follows: Figure 3 As shown, the equipment includes a second unwinding unit 14, a second coating unit 15, and a dual-path winding unit 16. The specific operation is as follows: After the finished carbon-coated aluminum foil prepared in step d is transported to the cell end, it is installed on the unwinding shaft of the positive electrode coating machine (corresponding to...). Figure 3 Second unwinding unit 14). A winding mechanism is added to the unwinding position of the positive electrode coating machine (corresponding to...). Figure 3 The upper winding roller 18 of the dual-path winding unit 16 is used to wind up the separated ceramic base film. Start the positive electrode coating machine (its coating module corresponds to...). Figure 3 The second coating unit 15) applies the positive electrode slurry to the carbon coating area of ​​the carbon-coated aluminum foil. During the coating process, the ceramic base film and the carbon-coated aluminum foil naturally separate. The ceramic base film is wound up by the added winding mechanism, namely the upper winding roller 18. The carbon-coated aluminum foil that has been coated is wound up by the lower winding roller 17 into a finished electrode roll.

[0043] After separation, check the integrity of the ceramic coating on the ceramic base film. If there is no obvious peeling or damage, return to step d and repeat the process.

[0044] When reusing the ceramic coating, the thickness change needs to be monitored: measure the coating thickness with a micrometer and calculate the difference between it and the thickness of the carbon-coated area on the carbon-coated aluminum foil (1.5 μm on one side). If the difference exceeds 0.5 μm, it indicates that the ceramic coating is excessively worn, and the coating should be discontinued and replaced with a new ceramic-coated base film. Testing showed that the ceramic-coated base film in this embodiment can be reused 5 times, at which point the thickness difference is still less than 0.5 μm, and the thickness difference between the blank area and the carbon-coated area after filling is ≤0.5 μm, maintaining stable alignment accuracy. The thickness difference exceeds 0.5 μm on the 6th reuse; therefore, a maximum of 5 uses is recommended.

[0045] Example 2 The difference between this embodiment and Embodiment 1 is that the ceramic powder material is different, but the other steps are the same as in Embodiment 1.

[0046] b. Preparation of ceramic slurry Weigh the following raw materials: 10 parts by weight of boehmite powder (average particle size D50 = 0.8 μm), 20 parts by weight of polyacrylic acid binder (solid content 25%), 1 part by weight of dispersant, and 70 parts by weight of deionized water. Prepare the ceramic slurry according to the method in step 2 of Example 1, controlling the solid content to be 15% ± 1% and the viscosity to be 200~500 mPa·s (25℃).

[0047] c. Preparation of ceramic-coated films The ceramic coating was applied according to step c of Example 1, with a coating speed of 30 m / min, a drying temperature of 100℃, and the ceramic coating thickness controlled to be 1.2 ± 0.2 μm.

[0048] Example 3 The difference between this embodiment and Embodiment 1 is that the polymer base film material is different; the other steps are the same as in Embodiment 1.

[0049] c. Preparation of ceramic-coated films A polypropylene (PP) base film (10 μm thick, 520 mm wide) was used instead of a PE base film, and the ceramic coating was applied according to step c of Example 1, controlling the ceramic coating thickness to be 1.8 ± 0.2 μm. According to GB / T 2790-1995 testing, the adhesion between the ceramic coating and the PP substrate was 14.2 N / m.

[0050] Comparative Example 1 The difference between this comparative example and Example 1 is that: synchronous winding with a ceramic-coated base film is not used; only a conventional winding process is employed. The carbon-coated aluminum foil is directly wound after coating, and the winding parameters are the same as in Example 1 (winding tension 70 N, winding speed 30 m / min).

[0051] Comparative Example 2 The difference between this comparative example and Example 1 is that the thickness of the ceramic coating on the ceramic substrate film is 0.5 ± 0.1 μm (less than the thickness of the single-sided coating on the carbon-coated aluminum foil, which is 1.5 μm). The other steps are the same as in Example 1.

[0052] Comparative Example 3 The difference between this comparative example and Example 1 is that the width of the ceramic coating on the ceramic substrate is 30 mm (less than the width of the blank area of ​​60 mm). The other steps are the same as in Example 1.

[0053] The performance of the carbon-coated aluminum foils prepared in the above embodiments and comparative examples was tested using the following methods: Coating thickness measurement: Using a micrometer (accuracy 0.001mm), five points were evenly selected along the width of the sample (10mm, 20mm from the edge, center, 20mm, 10mm) to measure the thickness difference before and after coating, and the average value was taken.

[0054] Adhesion test: According to GB / T 2790-1995 "Adhesives 180° Adhesion Test Method", the ceramic base film was cut into 25mm×200mm samples, and the samples were attached to the stainless steel plate with double-sided tape. The 180° peel test was carried out on a universal tensile testing machine at a speed of 100 mm / min, and the average force value during the peel process was recorded.

[0055] Dent rate statistics: After winding, visually inspect the blank area under natural light, and measure the height difference between the deepest point of the dent and the surrounding plane using a depth gauge (accuracy 0.01mm) by touching it with your fingers. A depth ≥ 0.5μm is considered a dent defect. Dent occurrence rate (%) = (number of dented rolls / total number of rolls) × 100%.

[0056] The test results for each embodiment and comparative example are shown in Table 1.

[0057] Table 1

[0058] The comparison shows that the ceramic coating thickness (1.2~1.8μm) of the ceramic-based film in Examples 1 to 3 is basically matched with the single-sided coating thickness (1.5μm) of the carbon-coated aluminum foil, and the sinking rate is controlled below 10%. In Example 3, a polypropylene base film combined with an alumina ceramic coating was used, achieving a 0% sinking rate. In contrast, the ceramic coating thickness in Comparative Example 2 was only 0.5μm, which could not completely fill the thickness difference, and the sinking rate increased to 40%. In Comparative Example 3, the width of the ceramic coating (30mm) was smaller than the width of the blank area (60mm), which could not completely cover the blank area, and the sinking rate also increased to 50%. This indicates that the precise matching of the thickness and width of the ceramic-based film with the carbon-coated aluminum foil is the key factor in eliminating sinking. Regarding the choice of base film material, the sinking rate of the polypropylene base film used in Example 3 was better than that of the polyethylene base film in Example 1. The reason for this is that the polypropylene base film has a higher surface tension (≥45dyn / cm), better adhesion to the ceramic coating, and a higher elastic modulus, resulting in less deformation during winding. The ceramic-coated film can be reused 5 times, and the adhesion retention rate remains above 92%. The incidence of pitting does not increase significantly, indicating that the present invention has excellent economy and practicality.

[0059] By using a ceramic-coated base film to fill the gaps in the blank areas of carbon-coated aluminum foil, the thickness difference between the carbon coating layer and the blank areas during winding is eliminated, which would cause air to be introduced into the blank areas of the aluminum foil. This reduces the deformation caused by the compression of the aluminum foil in the blank areas due to the inability of air to escape in time during the dense winding process, ultimately reducing the indentation and deformation marks in the blank areas of the entire roll of carbon-coated aluminum foil. The significance of this invention lies in providing a method and apparatus for eliminating indentations in the blank areas of carbon-coated aluminum foil, which meets market demand.

[0060] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

[0061] It should be particularly noted that the various embodiments listed in this specification and accompanying drawings are intended to illustrate the technical solutions and advantages of the present invention, and not to limit the scope of protection of the present invention. Without departing from the core ideas and technical effects of the present invention, those skilled in the art can make any form of improvement, substitution, combination, or modification to the structural arrangement, process parameters, material selection, control logic, etc., of the described embodiments; any obvious changes based on the same concept should be considered equivalent solutions of the present invention and should be included within the scope of protection defined by the claims of the present invention. The actual scope of protection of the present invention is determined by the appended claims and should be correctly understood in conjunction with the specification and accompanying drawings.

Claims

1. A method for eliminating the white space recesses of carbon-coated aluminum foil, characterized by, Includes the following steps: S1. Provide a ceramic-coated base film, wherein the ceramic-coated base film includes a polymer base film and a ceramic coating coated thereon; S2. During the carbon-coated aluminum foil coating process, the ceramic base film and the coated carbon-coated aluminum foil are wound up simultaneously, so that the ceramic coating covers the blank area of ​​the carbon-coated aluminum foil to fill the thickness difference between the blank area and the carbon-coated area.

2. The method of claim 1, wherein, It also includes the step of preparing the ceramic-coated base film: coating the polymer base film with a ceramic slurry, drying and curing it to form a ceramic coating, thereby obtaining the ceramic-coated base film.

3. The method of claim 1, wherein, Also includes: In subsequent cell manufacturing processes, the ceramic-coated base film is separated from the carbon-coated aluminum foil, and the separated ceramic-coated base film is recycled and reused.

4. The method of claim 1, wherein, The ratio of the thickness of the ceramic coating to the thickness of the single-sided coating of the carbon-coated aluminum foil is 0.8~1.2:

1.

5. The method of claim 1, wherein, The width of the ceramic coating is less than or equal to the width of the blank area of ​​the carbon-coated aluminum foil, and is not less than 90% of the width of the blank area.

6. The method of claim 5, wherein, The width of the ceramic coating is 1-3 mm narrower than the width of the blank area.

7. The method of claim 3, wherein, When reused, the service life is determined by monitoring the change in the thickness of the ceramic coating on the ceramic base film during reuse: when the difference between the thickness of the ceramic coating and the thickness of the single-sided coating of the carbon-coated aluminum foil exceeds 0.5 μm, the use is stopped and a new ceramic base film is replaced.

8. The method according to claim 1, characterized in that, The polymer base film is a polyethylene film, a polypropylene film, a polyacrylonitrile film, or a polyvinyl chloride film; the ceramic coating is formed by applying an alumina ceramic slurry, a boehmite ceramic slurry, or a zirconia ceramic slurry.

9. An apparatus for eliminating white-faced depressions in carbon-coated aluminum foil using the method described in any one of claims 1-8, characterized in that, include: The first coating unit is used to coat a carbon-coated conductive paste onto an aluminum foil substrate to form a carbon-coated aluminum foil. The first unwinding unit is used to unwind ceramic-coated films. The first winding unit is used to simultaneously wind up the carbon-coated aluminum foil and the ceramic-coated base film, so that the ceramic coating on the ceramic-coated base film covers the blank area of ​​the carbon-coated aluminum foil. And a guide roller disposed between the first coating unit and the first winding unit, used to guide the carbon-coated aluminum foil and the ceramic-coated base film to bond together.

10. The apparatus of claim 9, wherein, It also includes a cell-end separation unit, which includes: The second unwinding unit is used to unwind the composite roll of carbon-coated aluminum foil and ceramic-coated base film that has been simultaneously wound up; The second coating unit is used to coat the positive electrode slurry in the carbon coating area of ​​the carbon-coated aluminum foil; The dual-path winding unit includes an upper winding roller and a lower winding roller. The upper winding roller is used to wind up the separated ceramic-coated base film, and the lower winding roller is used to wind up the carbon-coated aluminum foil after the positive electrode slurry is applied.

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