Method and system for heating pole piece by using laser

Abstract

The invention discloses a method and system for heating a pole piece by using laser, and the method comprises the following steps: obtaining an image of the pole piece to be heated, processing the image, and recognizing the total width of the pole piece, the width of a coating region and the width of a blank region, so as to determine the positions of the coating region and the blank region; a continuous laser is combined with a laser shaping device to form a light spot matched with the size of the coating area to heat the coating area; an infrared image of the heated pole piece is obtained, a pole piece area lower than a temperature threshold value is recognized, and the pole piece area lower than the temperature threshold value is scanned and heated to a set temperature through a pulse laser; the rolling difficulty of the high-compaction-density pole piece can be reduced, the energy consumption is reduced, the heating temperature uniformity of the pole piece is improved, the thickness consistency of the pole piece is improved, and the phenomena of wrinkles and belt breakage are reduced.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery technology, specifically relating to a method and system for heating electrode sheets using laser. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] With the booming development of the new energy vehicle industry, problems such as long charging time and short driving range urgently need to be solved. Equipping lithium batteries with high energy density and fast charging rate is an effective way to solve these problems. Typically, high energy density lithium batteries also have high electrode compaction density. However, as the electrode compaction density increases, the pressure required for rolling also increases, leading to increased energy consumption. In addition, during the rolling process, it is difficult to control the consistency of electrode thickness, and wrinkles and breakage are prone to occur, placing more stringent requirements on equipment performance.

[0004] Currently, hot roll forming technology is commonly used to solve the above problems. For example, heat transfer oil is circulated directionally through a spiral channel to heat the roll body. Through hot roll forming, the electrode sheet is effectively softened, thereby reducing rolling force during the rolling process, improving thickness uniformity, and reducing the occurrence of wrinkles and strip breakage. However, hot roll pressing technology has the following problems: 1. The key to existing hot roll pressing technology lies in heating the roll itself. The roll body is usually designed as a hollow structure, and complex heating channels (for circulating heat transfer oil) or electric heating elements need to be integrated inside. This built-in heating scheme results in a complex roll body structure; 2. Hot roll heating is an indirect contact heating method, with a long energy transfer path and low efficiency; 3. Due to the layout limitations of the heating channels inside the hot roll or the uneven heating of the electric heating elements, it is difficult to ensure that the temperature of the entire roll surface is absolutely uniform in the axial direction during the process of heat conduction from the inside of the roll body to the surface. Usually, the temperature in the middle is high and the temperature at both ends is low; in addition, the contact time between the electrode and the roll is extremely short, and the heat exchange is insufficient, making it difficult to ensure that each section of the electrode can obtain a stable and consistent heating effect. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for heating electrode sheets using laser, which aims to reduce the difficulty of rolling high-density electrode sheets, reduce energy consumption, improve the temperature uniformity of electrode sheet heating, improve the consistency of electrode sheet thickness, and reduce the occurrence of wrinkles and strip breakage.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, embodiments of the present invention provide a method for heating an electrode using a laser, comprising the following steps: Step 1: Acquire an image of the electrode to be heated and process the image to identify the total width of the electrode, the width of the coated area, and the width of the blank area in order to determine the location of the coated area and the blank area. Step 2: Use a continuous laser combined with a laser shaping device to form a light spot that matches the size of the coating area and heat the coating area; Step 3: Acquire infrared images of the heated electrode, identify electrode areas below the temperature threshold, and use a pulsed laser to scan and heat the electrode areas below the temperature threshold to the set temperature.

[0007] As a further technical solution, in step one, the image of the electrode to be heated is sequentially subjected to filtering and noise reduction, binarization, and edge enhancement processing.

[0008] As a further technical solution, in step one, when identifying the total width of the electrode, an edge detection algorithm is used to extract the electrode outline, calculate the width of the minimum bounding rectangle of the outline, and then convert it into the physical width according to the camera calibration parameters; when determining the position of the coated area and the blank area, the region growing method or K-means clustering is used to segment the image and distinguish different areas.

[0009] As a further technical solution, in step two, the laser shaping device converts the identified coating area width into the target size of the light spot, and generates a voltage signal through a PID controller to drive the laser shaping device to adjust the light spot.

[0010] As a further technical solution, in step three, when identifying electrode areas below the temperature threshold, the target temperature and tolerance temperature are first set according to the process requirements; then, the infrared image is sequentially calibrated for temperature, segmented for region, and clustered for cluster analysis to identify the geometric center and circumscribed rectangle coordinates of the continuous low-temperature region; finally, the image coordinates of the low-temperature region are mapped to the scanning coordinate system of the pulsed laser galvanometer through affine transformation.

[0011] As a further technical solution, in step three, when using a pulsed laser for scanning heating, a grid scanning or shortest path algorithm is adopted to make the galvanometer traverse all low-temperature points in sequence. At the same time, the infrared thermal imager monitors the compensated temperature in real time. If it is still lower than the threshold, a second scan is triggered.

[0012] As a further technical solution, an overheat protection method is also included, which sets a maximum temperature limit and immediately stops irradiation at a point if the temperature at a certain point exceeds the maximum temperature.

[0013] Secondly, embodiments of the present invention provide a system for heating an electrode using a laser, comprising: A laser heating assembly includes a continuous laser, a laser shaping device, and a pulsed laser; the continuous laser is used to generate continuous laser light to heat the electrode, the laser shaping device is used to shape the laser light generated by the laser into a spot, and the pulsed laser is used to generate pulsed laser light to scan and heat the electrode area below a temperature threshold. An image acquisition component includes an industrial camera and an infrared camera, wherein the industrial camera is used to acquire an image of the electrode to be heated, and the infrared camera is used to acquire an infrared image of the electrode after heating. The controller is configured to: acquire an image of the electrode to be heated and process the image, identify the total width of the electrode, the width of the coated area, and the width of the blank area to determine the position of the coated area and the blank area; control a continuous laser in conjunction with a laser shaping device to form a light spot that matches the size of the coated area to heat the coated area; acquire an infrared image of the heated electrode, identify electrode areas below the temperature threshold, and control a pulsed laser to scan and heat the electrode areas below the temperature threshold to the set temperature.

[0014] As a further technical solution, the laser heating component is located above the electrode.

[0015] As a further technical solution, the laser shaping device is installed at the laser output end of the continuous laser.

[0016] The beneficial effects of the above embodiments of the present invention are as follows: This invention employs a sequence of heating first with a continuous laser and then with a pulsed laser. The continuous laser enables rapid overall heating of the electrode sheet, raising it to the target temperature in a very short time. This "surface heating" method first ensures uniform softening of the electrode substrate, reducing the rolling force required for roll forming and thus improving production efficiency. The initial continuous heating ensures the electrode sheet is essentially softened before entering the roll forming rolls, avoiding localized overcooling or overheating caused by direct pulse heating. During the electrode's conveyor belt operation, due to uneven material thickness or differences in heat dissipation, areas with low temperatures may appear after continuous heating. The pulsed laser, based on infrared thermometry feedback, then provides targeted compensation heating to these low-temperature points, precisely targeting the coated or uncoated areas to achieve differentiated heating and ensure uniform temperature across the width.

[0017] This invention achieves rapid and uniform substrate heating first through a continuous laser combined with a shaping device. Subsequently, an infrared thermal imager scans the entire electrode surface, generating a high-precision temperature field distribution map. The control system intelligently identifies "cold spots" below a threshold and drives a pulsed laser to perform millimeter-level or even higher precision point-to-point energy compensation, ensuring the temperature uniformity of the entire heating area of ​​the electrode before it enters the rolls. This high temperature uniformity directly translates to consistent stress during rolling, significantly improving the uniformity of electrode thickness, greatly reducing the risk of wrinkles and breakage, and ensuring the integrity of the electrode structure.

[0018] The method of the present invention can also achieve differentiated heating of the coated area and the blank area, meet the optimal process requirements of different areas, and further optimize the performance of the tab welding area and the active material area. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a flowchart of the method for heating an electrode using a laser according to the present invention; Figure 2 This is a schematic diagram of the system of the present invention that utilizes laser to heat the electrode plate; Figure 3 This is a schematic diagram of the coated area and the blank area on the electrode sheet of the present invention.

[0021] The diagram is for illustrative purposes only. Among them, 1. Industrial camera; 2. Continuous laser; 3. Laser shaping device; 4. Laser spot; 5. Infrared camera; 6. Electrode; 7. Pulsed laser; 8. Roller pressing roller; 9. Cooling roller; 10. Passing roller; 11. Coating area; 12. Blank area. Detailed Implementation

[0022] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] Example 1 In a typical embodiment of the present invention, such as Figure 1 and Figure 2 As shown, a method for heating an electrode using a laser is provided, comprising the following steps: Step 1: Acquire an image of the electrode to be heated and process the image to identify the total width of the electrode, the width of the coated area, and the width of the blank area in order to determine the location of the coated area and the blank area. Step 2: Use a continuous laser combined with a laser shaping device to form a light spot that matches the size of the coating area and heat the coating area; Step 3: Acquire infrared images of the heated electrode, identify electrode areas below the temperature threshold, and use a pulsed laser to scan and heat the electrode areas below the temperature threshold to the set temperature.

[0024] Each step is explained in detail below: Step 1: Acquire an image of the electrode to be heated and process the image to identify the total width of the electrode, the width of the coated area, and the width of the blank area in order to determine the location of the coated area and the blank area.

[0025] Specifically, the images of the electrodes to be heated are sequentially processed through filtering and denoising, binarization, and edge enhancement. A Gaussian filtering algorithm is used, convolving the image with a kernel (e.g., 3x3 or 5x5) to effectively suppress noise generated during acquisition. The Otsu algorithm is employed to automatically determine the optimal threshold, which distinguishes the foreground (electrode) from the background by maximizing the inter-class variance. After finding the threshold T, the image is converted into a binary image. The Canny edge detection operator is used, calculating the gradient magnitude and direction of the image, and employing non-maximum suppression and double-threshold hysteresis to obtain clear and continuous electrode edge contours, laying the foundation for subsequent dimensional measurements.

[0026] Furthermore, when identifying the total width of the electrode, an edge detection algorithm is used to extract the electrode outline, calculate the width of the minimum bounding rectangle of the outline, and then convert it into the physical width according to the camera calibration parameters; when determining the position of the coated area and the blank area, the region growing method or K-means clustering is used to segment the image and distinguish different areas.

[0027] Specifically, after edge enhancement, the outermost contour of the electrode is extracted using a contour-finding algorithm (such as the Suzuki85 algorithm). Then, the minimum bounding rectangle of this contour is calculated. The width (pixel value) of this rectangle is multiplied by the camera calibration coefficient to obtain the physical total width of the electrode. When using K-means clustering to segment the image, the pixel values ​​of the grayscale image are used as features. K=2 (for the shading area and the blank area), and the algorithm automatically iteratively calculates the center of the two clusters and assigns each pixel to the nearest cluster, thereby achieving region segmentation.

[0028] When segmenting an image using the region growing method, a seed point is selected in the blank area (usually with higher brightness). Based on a predefined gray-level similarity criterion, adjacent similar pixels are merged into this seed point until growth stops, thus separating the blank area. The remaining portion is the coated area. After segmentation, the centroid and bounding box of each region are calculated to accurately determine its location.

[0029] Step 2: Use a continuous laser combined with a laser shaping device to form a light spot that matches the size of the coating area and heat the coating area.

[0030] In this embodiment, the laser shaping device converts the identified coating area width into a target spot size, and generates a voltage signal through a PID controller to drive the laser shaping device to adjust the spot. Specifically, the input to the PID controller is the target spot size calculated based on the coating area width, and the feedback is the actual spot size measured in real time by an auxiliary spot quality monitoring instrument (such as a CCD). The controller calculates the error.

[0031] In the formula, Indicates the width of the target light spot. This indicates the actual beam width.

[0032] Generate control signals:

[0033] in, K p 、K i 、K d These are parameters obtained through engineering tuning.

[0034] The output is a control signal u(t) that drives the laser shaping device (such as the stepper motor of an electric zoom beam expander) to adjust the spot size until the error e(t) approaches zero.

[0035] Step 3: Acquire infrared images of the heated electrode, identify electrode areas below the temperature threshold, and use a pulsed laser to scan and heat the electrode areas below the temperature threshold to the set temperature.

[0036] In this embodiment, when identifying electrode regions below the temperature threshold, the target temperature and tolerance temperature are first set according to process requirements; then, the infrared image is sequentially subjected to temperature calibration, region segmentation, and cluster analysis to identify the geometric center and circumscribed rectangle coordinates of continuous low-temperature regions; finally, the image coordinates of the low-temperature regions are mapped to the scanning coordinate system of the pulsed laser galvanometer through affine transformation. Furthermore, when using a pulsed laser for scanning heating, a grid scanning or shortest path algorithm is employed to allow the galvanometer to sequentially traverse all low-temperature points. Simultaneously, an infrared thermal imager monitors the compensated temperature in real time, and if it is still below the threshold, a second scan is triggered.

[0037] Specifically, the radiation temperature measured by the infrared thermal imager is corrected based on the emissivity (ε) of the electrode material to obtain the true temperature: The calibrated thermal images are thresholded to identify all... The pixels (ΔT is the tolerance) are then analyzed. A connected component analysis algorithm (e.g., based on 8-neighborhood) is used to aggregate these discrete low-temperature pixels into independent "low-temperature regions," and the geometric center and circumscribed rectangle of each region are calculated. Through affine transformation, the coordinates (x, y, y) of the low-temperature regions in the infrared image are then determined. _image , y _image ) mapped to the scanning coordinate system (x) of the pulsed laser galvanometer mirror _galvo , y _galvo The transformation matrix is ​​determined through a pre-calibration process.

[0038] Furthermore, grid scanning is suitable for large-area low-temperature regions, with the galvanometer traversing the area in a zigzag pattern. Shortest path algorithms (such as the nearest neighbor method) are suitable for multiple dispersed low-temperature points to minimize the galvanometer's travel time and improve efficiency. The heating energy at each point is determined by the power of the pulsed laser and the irradiation time. After irradiation, the infrared thermal imager immediately detects the temperature at that point. If it is still below the threshold, the controller instructs the galvanometer to scan the point again and appropriately increase the energy (such as increasing the number of pulses or increasing the power), forming a real-time closed-loop feedback.

[0039] This embodiment also includes an overheat protection method. By setting a maximum temperature limit, if the temperature at a certain point exceeds the maximum temperature, irradiation at that point is immediately stopped. An absolute temperature upper limit T is set in the control software. _max (e.g., 180°C). When the infrared thermal imager detects that the temperature at any point during the heating process reaches or exceeds T... _max When this happens, the controller immediately sends an emergency stop signal to the pulsed laser (or continuous laser), interrupting the laser output at that point. This is a hard protection mechanism to prevent the electrodes from overheating, scorching, curling, or being damaged.

[0040] Example 2 In a typical embodiment of the present invention, a system for heating an electrode using a laser is provided, such as... Figure 3 As shown, it includes: The laser heating assembly includes a continuous laser 2, a laser shaping device 3, and a pulsed laser 7; the continuous laser is used to generate continuous laser to heat the electrode sheet, the laser shaping device is used to shape the laser generated by the connected laser into a light spot, and the pulsed laser is used to generate pulsed laser to scan and heat the electrode sheet area below the temperature threshold. The image acquisition component includes an industrial camera 1 and an infrared camera 5. The industrial camera is used to acquire images of the electrode to be heated, and the infrared camera is used to acquire infrared images of the electrode after heating. The controller is configured to: acquire an image of the electrode to be heated and process the image, identify the total width of the electrode, the width of the coated area and the width of the blank area to determine the positions of the coated area 10 and the blank area 11; control a continuous laser in conjunction with a laser shaping device to form a light spot that matches the size of the coated area to heat the coated area; acquire an infrared image of the heated electrode, identify electrode areas below the temperature threshold, and control a pulsed laser to scan and heat the electrode areas below the temperature threshold to the set temperature.

[0041] In this embodiment, the laser heating component is located above the electrode.

[0042] In this embodiment, the laser shaping device is installed at the laser output end of the continuous laser.

[0043] The continuous laser in this embodiment outputs a continuous and stable beam of laser light with adjustable power but no interruptions. The continuous laser is equipped with a laser shaping device to amplify and homogenize the laser spot, forming a uniform energy distribution. It achieves overall heating of the electrode across both the width and the belt travel direction through continuous light output, similar to a "surface heating" method. This heating method is suitable for rapidly increasing the overall temperature of the electrode, ensuring uniform softening of the substrate. The continuous laser controls the heating temperature by adjusting the power and, in conjunction with an infrared temperature measurement device, achieves closed-loop control to maintain temperature stability.

[0044] Pulsed lasers output intermittent pulses, each with an extremely short duration (e.g., nanoseconds), concentrating energy into an instantaneous release. Pulsed lasers are used for targeted, point-heating compensation in areas where temperatures are low after continuous laser heating—a type of "point heating." Based on thermal imaging feedback from an infrared thermometer, it precisely locates low-temperature points and rapidly raises the local temperature with high-energy pulses, preventing overall overheating or underheating. The advantages of pulsed lasers lie in their high precision and controllability, making them particularly suitable for treating heat-prone areas such as tabs or the edges of coated areas.

[0045] The number of continuous lasers and pulsed lasers is set according to the number of coated areas on the electrode to achieve synchronous heating of the coated areas during the electrode's conveying process.

[0046] This system employs a sequence of continuous laser heating followed by pulsed laser heating. The continuous laser rapidly heats the entire electrode sheet, raising it to the target temperature within a very short time (0.1-1 second). This "surface heating" method ensures uniform softening of the electrode substrate, reducing the rolling force required for pressing and thus improving production efficiency. Pre-heating with continuous laser heating ensures the electrode sheet is essentially softened before entering the pressing rolls, avoiding localized overcooling or overheating caused by direct pulsed heating. During the conveyor belt operation, due to uneven material thickness or heat dissipation differences, low-temperature areas (such as tabs or edges) may appear after continuous heating. The pulsed laser then uses infrared thermography feedback to precisely compensate for these low-temperature points, accurately targeting the coated or uncoated areas to achieve differentiated heating and ensure uniform temperature across the width.

[0047] In addition, the sequence of continuous laser followed by pulsed laser reduces the total energy consumption. After the continuous laser achieves basic heating, the pulsed laser only needs a small amount of energy to compensate for local conditions, thus avoiding the waste of high-energy pulses throughout the process.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for heating an electrode using a laser, characterized in that, Includes the following steps: Step 1: Acquire an image of the electrode to be heated and process the image to identify the total width of the electrode, the width of the coated area, and the width of the blank area in order to determine the location of the coated area and the blank area. Step 2: Use a continuous laser combined with a laser shaping device to form a light spot that matches the size of the coating area and heat the coating area; Step 3: Acquire infrared images of the heated electrode, identify electrode areas below the temperature threshold, and use a pulsed laser to scan and heat the electrode areas below the temperature threshold to the set temperature.

2. The method for heating an electrode using a laser as described in claim 1, characterized in that, In step one, the image of the electrode to be heated is sequentially subjected to filtering and noise reduction, binarization, and edge enhancement processing.

3. The method for heating an electrode using a laser as described in claim 1, characterized in that, In step one, when identifying the total width of the electrode, an edge detection algorithm is used to extract the electrode outline, calculate the width of the minimum bounding rectangle of the outline, and then convert it into the physical width according to the camera calibration parameters; when determining the position of the coated area and the blank area, the region growing method or K-means clustering is used to segment the image and distinguish different areas.

4. The method for heating an electrode using a laser as described in claim 1, characterized in that, In step two, the laser shaping device converts the identified coating area width into the target size of the light spot, and generates a voltage signal through a PID controller to drive the laser shaping device to adjust the light spot.

5. The method for heating an electrode using a laser as described in claim 1, characterized in that, In step three, when identifying electrode regions below the temperature threshold, the target temperature and tolerance temperature are first set according to the process requirements; then, the infrared image is sequentially calibrated for temperature, segmented for region, and clustered for cluster analysis to identify the geometric center and circumscribed rectangle coordinates of the continuous low-temperature region; finally, the image coordinates of the low-temperature region are mapped to the scanning coordinate system of the pulsed laser galvanometer through affine transformation.

6. The method for heating an electrode using a laser as described in claim 1, characterized in that, In step three, when using a pulsed laser for scanning heating, a grid scanning or shortest path algorithm is used to make the galvanometer traverse all low-temperature points in sequence. At the same time, the infrared thermal imager monitors the compensated temperature in real time. If it is still below the threshold, a second scan is triggered.

7. The method for heating an electrode using a laser as described in claim 1, characterized in that, It also includes overheat protection methods, which set a maximum temperature limit and immediately stop irradiation at a point if the temperature at a certain point exceeds the maximum temperature.

8. A system for heating an electrode using a laser, for implementing the method according to any one of claims 1-7, characterized in that, include: Laser heating assembly, including a continuous laser, a laser shaping device, and a pulsed laser; The continuous laser is used to generate continuous laser to heat the electrode sheet; the laser shaping device is used to shape the laser generated by the connected laser into a light spot; and the pulsed laser is used to generate pulsed laser to scan and heat the electrode sheet area below the temperature threshold. An image acquisition component includes an industrial camera and an infrared camera, wherein the industrial camera is used to acquire an image of the electrode to be heated, and the infrared camera is used to acquire an infrared image of the electrode after heating. The controller is configured to: acquire an image of the electrode to be heated and process the image, identify the total width of the electrode, the width of the coated area, and the width of the blank area to determine the position of the coated area and the blank area; control a continuous laser in conjunction with a laser shaping device to form a light spot that matches the size of the coated area to heat the coated area; acquire an infrared image of the heated electrode, identify electrode areas below the temperature threshold, and control a pulsed laser to scan and heat the electrode areas below the temperature threshold to the set temperature.

9. The system for heating an electrode using a laser as described in claim 8, characterized in that, The laser heating component is located above the electrode.

10. The system for heating an electrode using a laser as described in claim 8, characterized in that, The laser shaping device is installed at the laser output end of the continuous laser.

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