Integrated stepped gravure roller device and lithium ion battery pole piece coating method

Abstract

The invention discloses an integrated stepped gravure roller device and a lithium ion battery pole piece coating method. The gravure roller device adopts a gravure roller of an integrated stepped structure, the surface of a gravure roller body is divided into at least two seamlessly connected coating areas, different areas are provided with different pit depths and mesh numbers, and U-shaped ink cells are engraved by adopting hexagonal laser; the gravure roller is made of a high-strength alloy steel material, a temperature control system is integrated, and the multi-step area design can be expanded; the coating method is based on the gravure roller device, and seamless coating of pole pieces with different thicknesses is achieved by accurately controlling the rotating speed of the gravure roller body, the pole piece conveying speed and slurry supply parameters. According to the invention, the coating production efficiency is improved by about 30%, the thickness deviation is reduced to be within + / -3%, the internal resistance of the battery pole piece is reduced by 5-10%, the equipment cost is reduced by 20%, and the method is suitable for coating pole pieces in consumer batteries, power batteries and energy storage batteries, and can also be expanded to the field of electrode manufacturing of supercapacitors and fuel cells.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery manufacturing technology, specifically relating to an integrated stepped gravure roller device and a lithium-ion battery electrode coating method based on the device. Background Technology

[0002] With the rapid development of the new energy industry, lithium-ion batteries are widely used in small electronic devices, emergency power supplies, power tools, and new energy vehicles due to their advantages such as being pollution-free, having high energy density, and long cycle life. Electrode coating is the core process in lithium-ion battery manufacturing, and the coating quality directly affects key performance characteristics of the battery, such as internal resistance, capacity, and cycle life.

[0003] Currently, lithium-ion battery electrode coating technology often employs multiple independent gravure rollers to achieve coating thicknesses of varying degrees. This method has several drawbacks: First, frequent roller changes lead to low production efficiency and long downtime. Second, roller switching can easily create mechanical gaps, causing overlapping or gaps in the coating area, resulting in uneven electrode thickness and consequently increased battery internal resistance and reduced capacity. Third, traditional gravure rollers have a limited cell shape, often formed by conventional screen printing, resulting in poor paste flowability and further exacerbating thickness variations. Fourth, multi-roller systems have complex mechanical structures, high equipment costs, and are difficult to maintain.

[0004] The existing gravure rollers have fixed parameters such as pit depth and mesh count, making it impossible to achieve seamless coating of multiple thicknesses on the same gravure roller body. There is a need to propose an efficient and high-precision coating solution to improve the quality and efficiency of battery manufacturing. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an integrated stepped gravure roller device and a lithium-ion battery electrode coating method based on the device, solving the problems of low efficiency, poor uniformity, and insufficient battery consistency in multi-roller coating, achieving seamless coating of lithium-ion battery electrodes of different thicknesses, and improving production efficiency and product quality.

[0006] To achieve the above objectives, the present invention provides the following specific technical solutions: An integrated stepped gravure roller device for coating lithium-ion battery electrodes includes an integrated stepped gravure roller body, a bearing seat, and a temperature control system. The gravure roller body is made of high-strength alloy steel, and its surface is divided into at least two non-overlapping, seamless coating areas. The first coating area has a pit depth of 50-90 μm and a mesh size of 80-100, while the second coating area has a pit depth of 120-150 μm and a mesh size of 50-70. The coating areas of the gravure roller body all form U-shaped cavities. The gravure roller body is fixed to the bearing seat, and the temperature control system is integrated inside the gravure roller body to regulate the temperature of the gravure roller body.

[0007] In a preferred embodiment of the present invention, the high-strength alloy steel is 45# steel with a hardness of HB220-240; the welded joints of the gravure roller body are annealed, and the surface of the gravure roller body is free of burrs and sharp angles are blunted.

[0008] In a preferred embodiment of the present invention, the outer surface of the gravure roller body is plated with hard chrome, and the thickness of the chrome plating layer on one side is 0.08-0.12mm; the inner wall of the gravure roller body and both ends of the top plate are treated with rust prevention, and the thickness of the chrome plating layer on one side of the surface of this area is 0.02-0.03mm.

[0009] In a preferred embodiment of the present invention, the gravure roller body undergoes dynamic balancing testing, and the dynamic balancing accuracy reaches G2.5.

[0010] In a preferred embodiment of the present invention, the pit depth of the first coating region is 73 μm and the mesh count is 90, and the pit depth of the second coating region is 120 μm and the mesh count is 57; there is no overlap between the film length and gap of the first coating region and the second coating region, and they are seamlessly connected.

[0011] In a preferred embodiment of the present invention, the temperature control system includes a temperature sensor, a heating module, a heat dissipation module, and a control unit. The temperature sensor collects the temperature of the gravure roller body in real time, and the control unit dynamically adjusts the temperature of the gravure roller body to ensure that it is consistent with the preset temperature. The temperature of the gravure roller body is adjusted by the heating module or the heat dissipation module, and the temperature control accuracy is ±0.5℃. The control unit obtains the real-time temperature of the gravure roller body through the temperature sensor and compares it with the preset temperature: if the temperature is lower than the preset temperature, the heating module is activated to raise the temperature; if the temperature is higher than the preset temperature, the heat dissipation module is activated to lower the temperature, until the real-time temperature of the gravure roller body is consistent with the preset temperature.

[0012] In a preferred embodiment of the present invention, the gravure roller body is an expandable structure, and several stepped coating areas are added according to the coating requirements. The pit depth and mesh count of the newly added stepped coating areas are adjusted according to the electrode thickness requirements, and all the stepped coating areas are non-overlapping and seamlessly connected.

[0013] This invention provides a method for coating lithium-ion battery electrodes based on the aforementioned integrated stepped gravure roller device, comprising the following steps: Step 1, Assembly: Install the gravure roller body onto the bearing seat of the standard coating machine, connect the slurry supply system, electrode conveyor belt and temperature control system, check that there are no defects on the surface of the gravure roller body and that the coating areas are seamlessly connected. Step 2, parameter preset: Based on the electrode coating thickness requirements, set the temperature threshold of the temperature control system to stabilize the temperature of the gravure roller body; set the rotation speed of the gravure roller body and the conveying speed of the electrode conveyor belt to synchronize the rotation of the gravure roller body with the movement of the electrode. Step 3, slurry supply: The lithium-ion battery electrode coating slurry is delivered to the cells of the gravure roller body. The cells carry the corresponding amount of slurry according to their depth and mesh count. Step 4, seamless coating: The gravure roller rotates at a constant speed, transferring the slurry in the cells of the first coating area to the corresponding area of ​​the electrode to form a thinner coating; at the same time, the slurry in the cells of the second coating area is transferred to another corresponding area of ​​the electrode to form a thicker coating; the electrode moves at a constant speed with the conveyor belt to achieve seamless transition coating of different thicknesses. Step 5: Post-coating inspection. The thickness and surface flatness of the coated electrode are inspected, and the thickness deviation in each area is controlled within ±3%.

[0014] In a preferred embodiment of the present invention, in step 2, the rotational speed of the gravure roller body is 2-60 r / min, and the conveying speed of the electrode conveyor belt is 5-50 m / min; in step 3, the slurry supply pressure is 0.1-0.3 MPa, and the slurry viscosity is controlled at 0-2000 mPa·s.

[0015] In a preferred embodiment of the present invention, in step 5, a laser thickness gauge is used to detect the electrode thickness, and a flatness detector is used to detect the surface flatness of the electrode. The detection data is fed back to the coating machine control terminal in real time. If the thickness deviation exceeds ±3%, the rotation speed of the gravure roller body or the slurry supply pressure is adjusted.

[0016] Compared with the prior art, the present invention has the following significant advantages: (1) Improved production efficiency: The integrated stepped structure eliminates the need to replace the gravure roller, reducing equipment downtime and increasing coating production efficiency by about 30%.

[0017] (2) Improved coating accuracy: Hexagonal laser-engraved U-shaped cells optimize slurry flow, and seamless coating areas avoid coating overlap / discontinuity, reducing thickness deviation from ±10% to within ±3%.

[0018] (3) Battery performance optimization: The uniformity of electrode thickness is improved, which reduces the internal resistance of the battery electrode by 5-10% and significantly improves the cycle life. Laboratory tests show that the capacity retention rate of the electrode coated by this device exceeds 80% after 1200 cycles at RT, 700 cycles at 45℃, and 500 cycles at 50℃.

[0019] (4) Reduced equipment costs: The simplified mechanical structure of the multi-roller system reduces equipment costs by 20% and reduces maintenance difficulty.

[0020] (5) High versatility: The scalable stepped area design can adapt to the coating requirements of different types and sizes of batteries, and can also be extended to the manufacturing of supercapacitors, fuel cell electrodes and other fields, with a wide range of application prospects. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the film layer structure of the gravure roller body of the integrated stepped gravure roller device provided in an embodiment of the present invention.

[0023] Figure 2 A top view of the gravure roller body of an integrated stepped gravure roller device is provided for an embodiment of the present invention.

[0024] Figure 3 A side view of the gravure roller body of an integrated stepped gravure roller device is provided for an embodiment of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0026] like Figures 1-3As shown, this embodiment of the invention provides an integrated stepped gravure roller device for coating lithium-ion battery electrodes. It includes an integrated stepped gravure roller body, a bearing housing, and a temperature control system. The gravure roller body is made of high-strength alloy steel, with a preferred length of 1154 mm and a preferred diameter of 367.33 mm. A stainless steel layer 1 and an aluminum foil layer 2 are disposed on the gravure roller body. The surface of the gravure roller body is divided into at least two non-overlapping, seamless coating areas. The first coating area 3 has a pit depth of 50-90 μm and a mesh count of 80-100, while the second coating area 4 has a pit depth of 120-150 μm and a mesh count of 50-70. The first junctions 5 and 6 between the second coating area 4 and the first coating area 3 on both sides are non-overlapping and seamless. The coating areas of the gravure roller body all form U-shaped cells, preferably formed by laser engraving or electronic engraving of hexagonal or quadrilateral shapes. The U-shaped cavity structure optimizes the fluidity of the slurry, ensuring uniform coating thickness. Precision CNC machining between areas achieves seamless, non-overlapping transitions, preventing coating defects in the transition zone. The gravure roller body is fixed to the bearing housing, and a temperature control system is integrated inside the roller body to regulate its temperature and prevent changes in slurry viscosity. Mounting holes 7 with keyways are installed on the inner side of the roller body for easy connection to the bearing housing.

[0027] The high-strength alloy steel is 45# steel, with a hardness of HB220-240 after heat treatment; it can withstand the mechanical stress during the coating process, extending its service life. The welded joints of the gravure roller body are annealed, resulting in a strong and defect-free weld surface. Burrs and sharp angles are removed from the surface of the gravure roller body; unmarked chamfers are C0.5. Chamfering means removing burrs to make it smooth.

[0028] The outer surface of the gravure roller body is entirely plated with hard chrome, with a single-sided chrome plating thickness of 0.08-0.12 mm. The inner wall of the gravure roller body and both ends of the top plate are treated with rust prevention, and the single-sided chrome plating thickness in these areas is 0.02-0.03 mm. The gravure roller body undergoes dynamic balancing testing, achieving a dynamic balancing accuracy of G2.5. The surface of the gravure roller body is smooth, free of stains, rust spots, dents, and scratches. Clear steel stamped codes are also set on the cross-sections at both ends of the gravure roller body, with the codes referencing the drawing name and drawing number for easy traceability and management.

[0029] The pit depth of the first coating area is 73um and the mesh count is 90, while the pit depth of the second coating area is 120um and the mesh count is 57. The film length of the coating area is 0.5m~3m with a tolerance of ±0.2mm, and the film width is 0.1m~0.8m with a tolerance of ±0.2mm. There is no overlap in the length and gap between the first and second coating areas, and they are seamlessly connected.

[0030] The temperature control system includes a temperature sensor, a heating module, a heat dissipation module, and a control unit. The temperature sensor collects the real-time temperature of the gravure roller body, and the control unit dynamically adjusts the temperature of the gravure roller body to ensure it matches the preset temperature. The temperature control accuracy is ±0.5℃, effectively preventing viscosity fluctuations in the slurry due to temperature changes and ensuring coating quality. Specifically, the control unit obtains the real-time temperature of the gravure roller body through the temperature sensor and compares it with the preset temperature: if the temperature is lower than the preset temperature, the heating module is activated to raise the temperature; if the temperature is higher than the preset temperature, the heat dissipation module is activated to lower the temperature, until the real-time temperature of the gravure roller body matches the preset temperature.

[0031] The gravure roller body has an expandable structure, which can add more stepped coating areas according to coating needs. The pit depth and mesh count of the newly added coating areas can be adjusted according to the electrode thickness requirements, and all coating areas are non-overlapping and seamlessly connected, making it suitable for complex coating scenarios.

[0032] This invention employs an integrated stepped gravure roller design. By setting coating areas and buffer zones of varying thicknesses on the surface of the gravure roller body, precise control of coating thickness is achieved, effectively solving the problem of uneven coating thickness in traditional gravure roller coating and significantly improving the coating quality and consistency of the electrode sheets. The gravure roller of this invention uses a U-shaped cell design, which, compared to the traditional screen printing method of gravure rollers, offers higher precision and durability, effectively reducing wear and extending the service life of the coated separator. By setting non-overlapping areas and seamless connections on the surface of the gravure roller body, this invention avoids coating overlap and accumulation, further improving coating uniformity and consistency, and ensuring the quality stability of the electrode sheets. The gravure roller of this invention allows for flexible adjustment of coating parameters according to different thickness requirements, exhibiting strong adaptability and meeting the coating needs of different types and sizes of batteries, demonstrating good versatility and practicality.

[0033] This invention also provides a method for coating lithium-ion battery electrodes based on the above-mentioned integrated stepped gravure roller device, comprising the following steps: Step 1: Assembly of the device. Install the gravure roller body on the bearing seat of the standard coating machine, connect the slurry supply system, electrode conveyor belt and temperature control system, and check that there are no defects on the surface of the gravure roller body and that the coating areas are seamlessly connected.

[0034] In this embodiment, the gravure roller body is precisely installed on the bearing seat of a standard coating machine, ensuring that the axis of the gravure roller body is parallel to the guide rail of the coating machine; the slurry supply system and electrode conveyor belt are connected, and the power supply of the temperature control system is turned on; the surface of the gravure roller body is checked to be free of stains and scratches, the coating areas are seamlessly connected, and the bearing seat rotates without jamming.

[0035] Step 2: Parameter preset. Based on the electrode coating thickness requirements, set the temperature threshold of the temperature control system to stabilize the temperature of the gravure roller body. Set the rotation speed of the gravure roller body and the conveying speed of the electrode conveyor belt to ensure that the rotation of the gravure roller body and the movement of the electrode are synchronized without relative displacement. Specifically, in Step 2, the rotation speed of the gravure roller body is 2-60 r / min, and the conveying speed of the electrode conveyor belt is 5-50 m / min.

[0036] Step 3, slurry supply: The lithium-ion battery electrode coating slurry is delivered to the cells of the gravure roller body. Each cell carries a corresponding amount of slurry based on its own depth and mesh count; cells in different areas carry a corresponding amount of slurry based on differences in depth and mesh count. Specifically, in step 3, the slurry supply pressure is 0.1-0.3 MPa, and the slurry viscosity is controlled between 0-2000 mPa·s.

[0037] Step 4, seamless coating: The gravure roller rotates at a constant speed, transferring the slurry in the cells of the first coating area to the corresponding area of ​​the electrode to form a thinner coating; at the same time, the slurry in the cells of the second coating area is transferred to another corresponding area of ​​the electrode to form a thicker coating; the electrode moves at a constant speed with the conveyor belt to achieve seamless transition coating of different thicknesses, without overlap or breakage.

[0038] Step 5: Post-coating inspection. The coated electrode sheet is inspected for thickness and surface flatness, with thickness deviation controlled within ±3%. Specifically, in step 5, a laser thickness gauge is used to measure the electrode sheet thickness, and a flatness detector is used to measure the surface flatness. The inspection data is fed back to the coating machine control terminal in real time. If the thickness deviation exceeds ±3%, the rotation speed of the gravure roller body is adjusted to ensure stable coating quality. When the thickness deviation is positive, the rotation speed of the gravure roller body is increased, thereby increasing the conveyor belt speed; when the thickness deviation is negative, the rotation speed of the gravure roller body is decreased, thereby decreasing the conveyor belt speed. The ratio of the increased or decreased rotation speed of the gravure roller body is the thickness deviation. Alternatively, the electrode sheet thickness can be adjusted by adjusting the slurry supply pressure. The rotation speed of the gravure roller body is preferably automatically adjusted by the system.

[0039] The integrated stepped gravure roller device and coating method of this invention solve the core technical problem of multi-thickness coating of lithium-ion battery electrodes, significantly improving production efficiency and product quality, reducing equipment costs, and offering strong versatility. This technology can be applied on a large scale to electrode coating production lines for consumer batteries, power batteries, and energy storage batteries, and can also be extended to other coating industries, possessing significant industrial practicality and market value.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. The present invention is not limited to the above embodiments; the embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An integrated stepped gravure roller device for coating lithium-ion battery electrodes, characterized in that, The device includes an integrated stepped gravure roller body, a bearing housing, and a temperature control system. The gravure roller body is made of high-strength alloy steel, and its surface is divided into at least two non-overlapping, seamless coating areas. The first coating area has a pit depth of 50-90 μm and a mesh count of 80-100, while the second coating area has a pit depth of 120-150 μm and a mesh count of 50-70. The coating areas of the gravure roller body all form U-shaped cavities. The gravure roller body is fixed to the bearing housing, and the temperature control system is integrated inside the gravure roller body. The temperature control system is used to regulate the temperature of the gravure roller body.

2. The integrated stepped gravure roller device according to claim 1, characterized in that, The high-strength alloy steel is 45# steel with a hardness of HB220-240; the welded joints of the gravure roller body are annealed, and the surface of the gravure roller body is free of burrs and sharp angles are blunted.

3. The integrated stepped gravure roller device according to claim 1, characterized in that, The outer surface of the gravure roller body is plated with hard chrome, and the thickness of the chrome plating layer on one side is 0.08-0.12mm; the inner wall of the gravure roller body and both ends of the top plate are treated with rust prevention, and the thickness of the chrome plating layer on one side of the surface of this area is 0.02-0.03mm.

4. The integrated stepped gravure roller device according to claim 1, characterized in that, The gravure roller body undergoes dynamic balancing testing, and the dynamic balancing accuracy reaches G2.

5.

5. The integrated stepped gravure roller device according to claim 1, characterized in that, The pit depth of the first coating area is 73µm and the mesh count is 90, while the pit depth of the second coating area is 120µm and the mesh count is 57. The film length and gap of the first coating area and the second coating area have no overlapping area and are seamlessly connected.

6. The integrated stepped gravure roller device according to claim 1, characterized in that, The temperature control system includes a temperature sensor, a heating module, a heat dissipation module, and a control unit. The temperature sensor collects the temperature of the gravure roller body in real time, and the control unit dynamically adjusts the temperature of the gravure roller body to ensure that it is consistent with the preset temperature. The temperature of the gravure roller body is adjusted through the heating module or the heat dissipation module, and the temperature control accuracy is ±0.5℃. The control unit obtains the real-time temperature of the gravure roller body through the temperature sensor and compares it with the preset temperature: if it is lower than the preset temperature, the heating module is activated to raise the temperature; if it is higher than the preset temperature, the heat dissipation module is activated to lower the temperature, until the real-time temperature of the gravure roller body is consistent with the preset temperature.

7. The integrated stepped gravure roller device according to claim 1, characterized in that, The gravure roller body has an expandable structure, and several stepped coating areas can be added according to coating requirements. The pit depth and mesh count of the newly added stepped coating areas are adjusted according to the electrode thickness requirements, and all the stepped coating areas are non-overlapping and seamlessly connected.

8. A method for coating lithium-ion battery electrodes based on the integrated stepped gravure roller device according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Assembly of the device. Install the gravure roller body on the bearing seat of the standard coating machine, connect the slurry supply system, electrode conveyor belt and temperature control system, and check that there are no defects on the surface of the gravure roller body and that the coating areas are seamlessly connected. Step 2, parameter preset: According to the electrode coating thickness requirements, set the temperature of the temperature control system to stabilize the temperature of the gravure roller body; set the rotation speed of the gravure roller body and the conveying speed of the electrode conveyor belt to synchronize the rotation of the gravure roller body with the movement of the electrode. Step 3, slurry supply: The lithium-ion battery electrode coating slurry is delivered to the cells of the gravure roller body. The cells carry the corresponding amount of slurry according to their depth and mesh count. Step 4, seamless coating: The gravure roller body rotates at a constant speed to transfer the slurry in the cells of the first coating area to the corresponding area of ​​the electrode sheet, forming a thinner coating. At the same time, the slurry in the cells of the second coating area is transferred to another corresponding area of ​​the electrode to form a thicker coating. The electrode moves at a constant speed with the conveyor belt, achieving seamless transition coating of different thicknesses; Step 5: Post-coating inspection. The thickness and surface flatness of the coated electrode are inspected, and the thickness deviation in each area is controlled within ±3%.

9. The lithium-ion battery electrode coating method according to claim 8, characterized in that, In step 2, the rotation speed of the gravure roller body is 2-60 r / min, and the conveying speed of the electrode conveyor belt is 5-50 m / min; in step 3, the slurry supply pressure is 0.1-0.3 MPa, and the slurry viscosity is controlled at 0-2000 mPa·s.

10. The lithium-ion battery electrode coating method according to claim 8, characterized in that, In step 5, a laser thickness gauge is used to detect the electrode thickness, and a flatness tester is used to detect the flatness of the electrode surface. The detection data is fed back to the coating machine control terminal in real time. If the thickness deviation exceeds ±3%, the rotation speed of the gravure roller body or the slurry supply pressure is adjusted.

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