A secondary baking and stretching device for battery electrodes

Abstract

This invention discloses a secondary baking and stretching device for battery electrodes, belonging to the field of industrial production technology. The invention includes a support frame; the electrode passes sequentially through a first tension detection module, a first swing roller module, a first partition module, a first heat treatment module, a second swing roller module, a second partition module, a second tension detection module, a third swing roller module, and a third partition module along a conveyor belt path. This invention uses a graded heat treatment strategy to create a gradient stress distribution in the electrode tab region, maintaining the interfacial bonding force between the current collector and the active material layer while significantly improving the longitudinal elongation. After process optimization, the electrode waviness and breakage rate are reduced, providing key process equipment for high-energy-density battery manufacturing.

Description

Technical Field

[0001] This utility model relates to the field of industrial production technology, specifically a secondary baking and stretching device for battery electrodes. Background Technology

[0002] In the lithium-ion battery electrode rolling process, the difference in longitudinal elongation between the electrode substrate and the current collector aluminum foil can lead to wavy edge defects in the tab area. Specifically, the active material layer of the electrode undergoes plastic deformation during rolling, while the 6-20μm thick aluminum foil substrate cannot elongate synchronously, resulting in wrinkles during the tab winding stage, which severely affects the positioning accuracy of subsequent tab welding processes. Existing technologies using single-stage tension control stretching devices have two drawbacks: first, when the tension value exceeds the tensile strength of the aluminum foil substrate, strip breakage is likely to occur in the tab area; second, room temperature stretching processes reduce the interfacial bonding force between the active material layer of the electrode and the aluminum foil, easily leading to potential electrode quality issues. Utility Model Content

[0003] In view of this, this utility model provides a secondary baking and stretching device for battery electrodes. Through a graded heat treatment strategy, it creates a gradient stress distribution in the electrode tab region, maintaining the interfacial bonding force between the current collector and the active material layer while significantly improving the longitudinal elongation. After process optimization, the electrode waviness and breakage rate are reduced, providing key process equipment for high-energy-density battery manufacturing.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A secondary baking and stretching device for battery electrodes includes a support frame; the electrode passes sequentially through a first tension detection module, a first swing roller module, a first partition module, a first heat treatment module, a second swing roller module, a second partition module, a second tension detection module, a second heat treatment module, a third swing roller module, and a third partition module along a conveyor belt path.

[0005] Furthermore, the main body of the heating module is an insulated box mounted on a support frame, with an air inlet and an air outlet on the insulated box; an infrared lamp heating assembly is installed inside the insulated box; the infrared lamp assembly includes a lamp tube, a baffle plate, a cooling duct, and a lamp cover; the lamp cover faces the electrode, and the lamp tube and cooling duct are located on the front and back sides of the lamp cover, respectively, with the lamp tube close to the electrode; one end of the cooling duct is connected to the air inlet of the insulated box, and the other end is connected to the exhaust vents arrayed on the lamp cover, with the exhaust vents facing the lamp tube; a baffle plate is also installed on the lamp cover, and the baffle plate is located between the lamp tube and the electrode.

[0006] Furthermore, each tension detection module includes a tension roller, a tension sensor, and a fixed bracket; the fixed bracket is mounted on a support frame, and tension sensors are located between the bearing seats at both ends of the tension roller and the fixed bracket; the two ends of the tension roller are connected to the corresponding bearing seats through bearings.

[0007] Furthermore, each swing roller module includes a swing roller, a swing arm a, a cylinder a, and a displacement gauge; the swing arm a and the cylinder a each have two sets, and the two sets of cylinder a are arranged parallel to each other on the support frame and hinged to the support frame; one end of the swing arm a is hinged to the piston end of the corresponding cylinder a, and the other end is fixedly connected to the rotating shaft a; both ends of the rotating shaft a are connected to the support frame bearings; the swing roller is located on one side of the rotating shaft a and is parallel to the rotating shaft a; the rotating shaft a is provided with two parallel side plates a, the swing roller is located between the two side plates a, and both ends are connected to the corresponding side plates a by bearings; the displacement gauge is installed on the cylinder a and is used to detect the extension length of the piston of the cylinder a.

[0008] Furthermore, each partition module includes a rubber roller, a steel roller, a swing arm b, a cylinder b, and a rotating shaft b; the swing arm b and the cylinder b each have two sets, and the two sets of cylinder b are arranged parallel to each other on the support frame and connected to the support frame; one end of the swing arm b is hinged to the piston end of the corresponding cylinder a, and the other end is hinged to the rotating shaft b; both ends of the rotating shaft b are fixedly connected to the support frame; the rubber roller is located on one side of the rotating shaft b, between the two swing arms, and connected to the swing arm bearing; both ends of the steel roller are connected to the support frame bearing, and are located to the side of the rubber roller and parallel to the rubber roller; the extension amount of the piston of the cylinder b is negatively correlated with the gap between the fixed steel roller and the swing roller.

[0009] Furthermore, a thickness measuring chamber is provided below the support frame, and a laser thickness gauge is installed inside the thickness measuring chamber to measure the thickness of the electrode sheet after secondary baking and stretching.

[0010] Furthermore, the heat treatment module's insulation box is equipped with one or more of the infrared lamp heating assembly and electromagnetic heating device.

[0011] Furthermore, both the tension roller in the tension detection module and the swing roller in the swing roller module are electromagnetic heating rollers, and a heat-insulating coating is provided on a portion of the electromagnetic heating roller.

[0012] The beneficial effects of adopting the above-mentioned optimized technical solution are as follows: To address the shortcomings of existing single-stage tension control devices that are prone to breakage due to tension exceeding the tensile strength of aluminum foil, this application achieves a breakthrough improvement through graded tension control and independent interval design. The device employs a tension isolation module to form multiple independent tension control intervals. Combined with a swing roller module for dynamic adjustment of the tension value in each interval, and a thermo-mechanical coupling process involving secondary baking, the tab area is subjected to tensile forces matching its mechanical properties at different temperature stages. Secondary stretching applies initial force when the material is in a highly elastic state, while tertiary stretching applies high tension within the recrystallization temperature range. This avoids the problem of difficulty in accurately matching tension values ​​to material characteristics in single-stage tension control, significantly reducing the breakage rate in the tab area and resolving the technical contradiction of "excessive tension leading to breakage" in existing technologies. To address the defect of decreased interfacial adhesion between the active material layer and aluminum foil caused by room temperature stretching, this application employs a graded heat treatment and thermo-coupling process to effectively maintain interfacial adhesion. Before the second stretching, preheating with infrared lamps brings the material into a highly elastic state, preventing the active material particles from detaching during room temperature stretching. Before the third stretching, the temperature is raised to the recrystallization temperature range, creating a gradient stress distribution. This achieves both increased longitudinal elongation and prevents a decrease in interfacial adhesion. This graded heating strategy resolves the technical contradiction between "increasing elongation and maintaining interfacial adhesion" in existing room temperature stretching processes, reduces the quality risk of separation between the active material layer and aluminum foil, and improves the overall quality stability of the electrode. The heating module design offers unique advantages in terms of heating precision and equipment reliability. The baffle divides the heating area into a tab heating zone and a non-heated baffle zone, enabling directional heating of the tab area and preventing damage to the active material in the non-tab area due to overheating. The cooling ducts, lamp covers, and other structures prevent the evaporation of the infrared lamp coating, ensuring the long-term stable operation of the heating components. Compared to existing devices lacking precise heating control, this further improves process stability and equipment lifespan.

[0013] After the process optimization in this application, the amplitude of electrode wavy edge is significantly reduced and the breakage rate is significantly decreased. This not only improves the flatness of the electrode to ensure the positioning accuracy of subsequent electrode tab welding, but also provides key process support for the manufacturing of high energy density batteries. It effectively solves the technical contradictions in the manufacturing of lithium-ion battery electrodes and has important industrial application value.

[0014] In terms of production line adaptability and safety, the overall layout of the device retains the space of the original thickness measuring mechanism, which can be seamlessly integrated with the existing production line, meet the needs of old equipment renovation, and reduce the equipment upgrade cost for enterprises. At the same time, the insulated box achieves physical isolation between the high-temperature area and the operating area. Combined with the safety protection design of the air intake and exhaust system, it significantly improves the safety of the production process and solves the shortcomings of the existing stretching device in production line integration and safety protection. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model.

[0016] Figure 2 This is a schematic diagram of the structure of the swing roller module in an embodiment of this utility model.

[0017] Figure 3 This is a schematic diagram of the partition module in an embodiment of this utility model.

[0018] Figure 4 This is a schematic diagram of the heating treatment module in an embodiment of this utility model.

[0019] Figure 5 yes Figure 4 A schematic diagram of the infrared lamp heating assembly inside the insulated box.

[0020] Figure 6 This is a schematic diagram showing the structural positions of the thickness measuring box and support frame of this utility model.

[0021] In the diagram: 1. Tension roller (first tension roller assembly), 2. Through roller, 3. Swing roller (first swing roller assembly), 4. Steel roller, 5. Rubber roller (first partition assembly), 6. Infrared lamp heating assembly, 7. Insulation box, 8. Cooling air inlet, 9. Exhaust outlet, 10. Swing roller (second swing roller assembly), 11. Steel roller, 12. Rubber roller (second partition assembly), 13. Tension roller (second tension roller assembly), 14. Second heat treatment assembly, 15. Swing roller (third swing roller assembly) 16. Steel roller, 17. Rubber roller (third partition assembly), 18. Thickness measuring box, 19. Support frame, 20. Infrared lamp tube, 21. Baffle plate, 22. Cooling air duct, 23. Lamp cover, 24. Electrode ear, 25. Electrode sheet, 26. Heating area, 27. Baffle area, 3-1. Rotating shaft a, 3-2. Swing arm a, 3-3. Swing roller, 3-4. Cylinder a, 3-5. Displacement gauge, 5-1. Rubber roller, 5-2. Swing arm b, 5-3. Rotation b, 5-4. Cylinder b. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings.

[0023] The secondary baking and grading stretching apparatus proposed in this embodiment effectively solves the technical contradictions in lithium-ion battery electrode manufacturing through innovative thermo-mechanical coupling technology. Before the first stretching process, the apparatus preheats the tab area using infrared lamps, at which point the material enters a highly elastic state. An initial stretching force is applied through a tension adjustment system controlled by a servo motor, achieving pre-stretch deformation while preventing the active material particles from detaching. Before the second stretching process, a high-power infrared lamp raises the temperature of the tab section to the recrystallization temperature range. This grading heat treatment strategy creates a gradient stress distribution in the tab area, maintaining the interfacial bonding force between the current collector and the active material layer while significantly improving the longitudinal elongation. After process optimization, the electrode waviness and breakage rate are reduced, providing key process equipment for high-energy-density battery manufacturing.

[0024] Reference Figure 1 After the electrode sheet is output from the main rolling mill, it passes through the following functional modules in sequence along the conveyor belt path: first tension detection module, first swing roller module, first partition module, first heat treatment module, second swing roller module, second partition module, second tension detection module, second heat treatment module, third swing roller module, and third partition module.

[0025] The first tension detection module and the second tension detection module have the same structure. The tension detection module consists of a tension roller, a tension sensor and a fixed bracket. The tension roller is fixed on the support frame by the bracket. Both ends of the tension roller are connected to the corresponding bearing seats through bearings. There are tension sensors between the bearing seats at both ends of the tension roller and the fixed bracket to collect the tension value of the tension interval in real time.

[0026] The first, second, and third swing roller modules have the same structure, as detailed below. Figure 2 Each swing roller module includes a swing roller, a swing arm a, a cylinder a, and a displacement gauge; the swing arm a and the cylinder a each have two sets, and the two sets of cylinder a are arranged in parallel on the support frame and hinged to the support frame; one end of the swing arm a is hinged to the piston end of the corresponding cylinder a, and the other end is fixedly connected to the rotating shaft a; both ends of the rotating shaft a are connected to the support frame bearings; the swing roller is located on one side of the rotating shaft a and is parallel to the rotating shaft a; the rotating shaft a has two parallel side plates a, the swing roller is located between the two side plates a, and both ends are connected to the corresponding side plates a by bearings; the displacement gauge is installed on the cylinder a and is used to detect the extension length of the piston of the cylinder a.

[0027] The tension sensor provides feedback on the tension, which is then processed by the PLC. The output signal is sent to the cylinder of the swing roller module. The extension length of the piston in the cylinder controls the tension, completing the tension closed loop. A displacement gauge detects the piston's extension length as the position determination.

[0028] The first partition module, the second partition module, and the third partition module have basically the same structure; see details below. Figure 3 Each partition module includes a rubber roller, a steel roller, a swing arm b, a cylinder b, and a rotating shaft b. The swing arm b and the cylinder b each have two sets, and the two sets of cylinder b are arranged parallel to each other on a support frame and connected to the support frame. One end of the swing arm b is hinged to the piston end of the corresponding cylinder a, and the other end is hinged to the rotating shaft b. Both ends of the rotating shaft b are fixedly connected to the support frame. The rubber roller is located on one side of the rotating shaft b, between the two swing arms, and connected to the swing arm bearing. Both ends of the steel roller are connected to the support frame bearings, located to the side of the rubber roller, and parallel to the rubber roller. The extension amount of the piston of cylinder b is negatively correlated with the gap between the fixed steel roller and the swing roller; that is, the longer the piston extension length of cylinder b, the smaller the gap between the steel roller and the swing roller.

[0029] The first and second heating treatment modules have basically the same structure, refer to Figure 4 and Figure 5 Each heating module consists of an insulated box mounted on a support frame, with an air inlet and an air outlet. An infrared lamp heating assembly is installed inside the insulated box. This assembly includes a lamp, a baffle plate, a cooling duct, and a lampshade. The lampshade faces the electrode, with the lamp and cooling duct located on the front and back sides of the lampshade, respectively, with the lamp closer to the electrode. One end of the cooling duct connects to the air inlet of the insulated box, and the other end connects to an array of exhaust vents on the lampshade, with the exhaust vents facing the lamp. A baffle plate is also installed on the lampshade, positioned between the lamp and the electrode.

[0030] Reference Figure 6 In this embodiment, the main support structure is a support frame. The first tension detection module, the first swing roller module, the first partition module, the first heat treatment module, the second swing roller module, the second partition module, the second tension detection module, the third swing roller module, the third partition module, and the thickness measurement module are all installed on the top of the support frame. A thickness measurement box is set at the bottom of the support frame, and a laser thickness gauge is set in the thickness measurement box to detect the thickness of the final product.

[0031] This embodiment constitutes a multi-module collaborative tension control system: it consists of an independent tension control zone composed of a tension detection module, a swing roller module, and a partition module. Tension is dynamically adjusted by the swing roller's oscillation, achieving precise tension control during graded stretching. This structure solves the problem of easy belt breakage in single-stage tension control; its modular combination and tension adjustment logic are the core protection points of the device structure.

[0032] The directional heating module includes an infrared lamp assembly with a shield, dividing the heating area into a tab heating zone and a non-heated shielded zone. Combined with air intake, exhaust, and cooling ducts, it achieves directional and stable heating. This design enables precise heating of the tab area, preventing damage to non-target areas; its structural layout and functional configuration require careful protection. The thermo-mechanical integrated device layout: Various functional modules (tension detection, roller support, oscillating roller control, etc.) are sequentially connected along the conveyor belt path, preserving space for the original thickness measurement mechanism to achieve production line integration. Simultaneously, an insulated enclosure isolates high-temperature areas to ensure safety.

[0033] The two-stage baking and heating strategy involves preheating the tab region to a highly elastic state using infrared lamps before the second stretching, and then raising it to the recrystallization temperature range before the third stretching, thus creating a gradient stress distribution. This strategy achieves a synergistic effect of increasing the elongation of the tab region and maintaining interfacial bonding through staged heat treatment, which differs from the existing room-temperature single-stage stretching process and is the core process for resolving technical contradictions.

[0034] Thermo-mechanical parameter matching control: The tension adjustment system is controlled by cylinder b to apply corresponding tensile force at different heating stages. Pre-stretching prevents the active material from falling off, and three stretchings achieve significant extension, forming a "temperature-tension" coupled control logic.

[0035] The following embodiments also exist as alternatives: 1. Electromagnetic induction heating head graded heating scheme: This scheme retains the core process logic of secondary baking and graded stretching, replacing the infrared lamp assembly in the heating module with an electromagnetic heating device (IHA). A magnetic heating head with the same width as the tab area is fixed near the swing roller module. An eddy current effect is generated inside the aluminum foil substrate of the tab area through a high-frequency alternating electromagnetic magnetic field, achieving directional heating of the tab area. Before secondary stretching, low-power electromagnetic heating brings the tab temperature to the high-elasticity range (corresponding to the original preheating process); before tertiary stretching, the electromagnetic heating power is increased to raise the tab temperature to the recrystallization temperature range (corresponding to the original secondary heating process). The advantages of this scheme are faster electromagnetic heating response, achieving millisecond-level temperature control, and easier mechanical positioning to ensure the width matching between the magnetic heating head and the tab, further improving the accuracy of the heating area. Simultaneously, electromagnetic heating does not need to contact the electrode surface, reducing physical disturbance to the active material layer. However, it needs to address the issue of non-target area heating caused by magnetic field leakage at the edge of the heating head.

[0036] 2. Electromagnetic Heating Roller Integrated Heating Solution: This solution replaces the ordinary rollers in the overroller support module or swing roller module with electromagnetic heating rollers. Heating is achieved directly through electromagnetic induction, with the temperature rising via heat conduction when the electrode contacts the heating roller. In the initial stretching zone, the heating roller temperature is controlled to achieve a highly elastic state in the tab area; in the third stretching zone, the heating roller temperature is increased to the recrystallization temperature range, creating a graded temperature field. This solution integrates heating and support functions, simplifying the equipment structure and reducing the space occupied by independent heating modules. Roller contact heating results in a more uniform temperature distribution on the electrode, making it particularly suitable for applications with wider electrode widths. It is important to note that a heat-insulating coating must be designed on the roller surface to prevent excessive temperature rise in non-tab areas due to contact heating.

[0037] 3. A hot air circulation heating staged scheme uses high-temperature hot air nozzles to replace infrared lamp components, and two independent hot air systems are set up inside the insulation box. Before the second stretching, the first set of hot air nozzles sprays a medium-temperature airflow (80-120℃) into the tab area to achieve preheating and softening; before the third stretching, the second set of hot air nozzles sprays a high-temperature airflow (150-200℃) to bring the tab to the recrystallization temperature. The hot air system precisely controls the airflow and temperature through air valves, and the baffle plate still divides the tab heating zone and non-heating zone. The advantage of this scheme is that it has good heating uniformity, avoids the local overheating phenomenon that may occur with infrared heating, and the hot air can also remove trace volatiles from the surface of the electrode, which is beneficial to improving the stability of the interfacial bonding. However, the air duct design needs to be optimized to reduce heat loss.

[0038] All the above alternative solutions follow the core utility model concept of "graded heating to regulate the mechanical state of the material + graded stretching to coordinate the elongation rate". They only replace the way heating energy is transferred, and can all achieve the utility model objectives of reducing wave amplitude, reducing the breakage rate and maintaining the interfacial bonding force.

[0039] The protection extension points of the alternative solutions are heating method alternatives based on the core utility model concept, such as electromagnetic heating head directional heating, electromagnetic heating roller integrated heating, hot air circulation graded heating, etc., which follow the logic of "graded heating + graded stretching" and the synergistic mechanism with tension control.

[0040] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. A battery pole piece secondary baking and stretching device, comprising a support frame; characterized in that, The electrode sheets pass through the first tension detection module, the first swing roller module, the first partition module, the first heat treatment module, the second swing roller module, the second partition module, the second tension detection module, the second heat treatment module, the third swing roller module, and the third partition module in sequence along the conveyor belt path.

2. The battery pole piece secondary baking and stretching device according to claim 1, characterized in that, The main body of the heating module is an insulated box mounted on a support frame, with an air inlet and an air outlet on the box. An infrared lamp heating assembly is installed inside the insulated box. The infrared lamp heating assembly includes a lamp, a baffle plate, a cooling duct, and a lamp cover. The lamp cover faces the electrode, and the lamp and cooling duct are located on the front and back sides of the lamp cover, respectively, with the lamp close to the electrode. One end of the cooling duct is connected to the air inlet of the insulated box, and the other end is connected to an array of exhaust vents on the lamp cover, with the exhaust vent facing the lamp. A baffle plate is also installed on the lamp cover, and the baffle plate is located between the lamp and the electrode.

3. The battery pole piece secondary baking and stretching device according to claim 1, characterized in that, Each tension detection module includes a tension roller, a tension sensor, and a fixed bracket; the fixed bracket is mounted on a support frame, and the tension sensor is located between the bearing seats at both ends of the tension roller and the fixed bracket; the two ends of the tension roller are connected to the corresponding bearing seats through bearings.

4. The battery pole piece secondary baking and stretching device according to claim 1, characterized in that, Each swing roller module includes a swing roller, a swing arm a, a cylinder a, and a displacement gauge; the swing arm a and the cylinder a each have two sets, and the two sets of cylinder a are arranged parallel to each other on the support frame and hinged to the support frame; one end of the swing arm a is hinged to the piston end of the corresponding cylinder a, and the other end is fixedly connected to the rotating shaft a; both ends of the rotating shaft a are connected to the support frame bearings; the swing roller is located on one side of the rotating shaft a and is parallel to the rotating shaft a; the rotating shaft a has two parallel side plates a, the swing roller is located between the two side plates a, and both ends are connected to the corresponding side plates a by bearings; the displacement gauge is installed on the cylinder a and is used to detect the extension length of the piston of the cylinder a.

5. The battery pole piece secondary baking and stretching device according to claim 1, characterized in that, Each partition module includes a rubber roller, a steel roller, a swing arm b, a cylinder b, and a rotating shaft b. The swing arm b and the cylinder b each have two sets, and the two sets of cylinder b are arranged parallel to each other on a support frame and connected to the support frame. One end of the swing arm b is hinged to the piston end of the corresponding cylinder a, and the other end is hinged to the rotating shaft b. Both ends of the rotating shaft b are fixedly connected to the support frame. The rubber roller is located on one side of the rotating shaft b, between the two swing arms, and connected to the swing arm bearing. Both ends of the steel roller are connected to the support frame bearings, located to the side of the rubber roller, and parallel to the rubber roller. The extension amount of the piston of the cylinder b is negatively correlated with the gap between the fixed steel roller and the swing roller.

6. The battery pole piece secondary baking and stretching device according to claim 1, characterized in that, Below the support frame is a thickness measuring chamber, which contains a laser thickness gauge used to measure the thickness of the electrode sheet after secondary baking and stretching.

7. The battery pole piece secondary baking and stretching device according to claim 2, characterized in that, The heat treatment module's insulation box is equipped with one or more of the infrared lamp heating assembly and electromagnetic heating device.

8. The battery pole piece secondary baking and stretching device according to claim 1, characterized in that, Both the tension roller in the tension detection module and the swing roller in the swing roller module are electromagnetic heating rollers, and some parts of the electromagnetic heating roller are provided with a heat insulation coating.

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