Battery pole piece coating abnormity detection method and system based on double-sided thickness

Abstract

The invention provides a battery pole piece coating abnormity detection method and system based on double-sided thickness. The method comprises the following steps: coating a first surface of a battery base material to obtain a first surface pole piece; when a coating initial position is marked, detecting the first surface pole piece based on the first optical contour sensing device array to obtain a first thickness sequence; coating the second surface of the first surface pole piece base material to obtain a second surface pole piece; when a coating initial position is identified, detecting a second surface pole piece based on a second optical contour sensing device array to obtain a second thickness sequence; and obtaining a thickness characteristic parameter through the first thickness sequence and the second thickness sequence, and comparing the thickness characteristic parameter with a preset threshold value to judge whether the coating area of the base material is abnormal or not. According to the method, the coating quality of the whole area of the two surfaces of the pole piece can be detected in real time, and coating abnormity can be found in time.

Description

Technical Field

[0001] This invention relates to the field of battery testing technology, specifically to a method and system for detecting abnormalities in battery electrode coating based on double-sided thickness. Background Technology

[0002] Thinning is an extremely important parameter control item in the battery cell manufacturing process and a crucial indicator affecting cell safety. Currently, the detection of the thinned area in batteries is carried out using offline detection methods. After coating, the electrode sheet is taken and the thickness and width of the thinned area are measured using a micrometer or an offline laser thickness gauge. However, existing offline inspection methods cannot achieve real-time monitoring of thinning and widening, resulting in a significant lag in guiding production line adjustments. Existing online inspection technologies, such as "Z-shaped" scanning, can only perform intermittent sampling inspections, resulting in a large quality blind spot and an inability to perform full-area inspection of the electrode thinning area and the normally coated area. Furthermore, existing methods can only measure the sum of "side A + substrate + side B," thus vaguely inferring the condition of side B, leading to extremely inaccurate results. Alternatively, they may employ destructive methods such as manually peeling off side A for inspection, failing to provide non-destructive, real-time production guidance. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies by providing a method and system for detecting abnormalities in battery electrode coating based on double-sided thickness.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for detecting abnormal coating on battery electrode sheets based on double-sided thickness includes the following steps: The first surface of the battery substrate is coated and dried to obtain the first electrode sheet; The coating start position is marked, and the height profile of the first surface electrode is obtained and preprocessed based on the first optical profile sensing device array to obtain the first thickness sequence. The second electrode is obtained by coating and drying the second surface of the battery substrate of the first electrode. When the coating start position is identified, the height profile of the second surface electrode is obtained and preprocessed based on the second optical profile sensing device array to obtain the second thickness sequence. The first thickness feature parameter and the second thickness feature parameter are compared with a preset threshold to determine whether there is an anomaly in the coating area of ​​the electrode; wherein, the first thickness feature parameter is obtained through a first thickness sequence, and the second thickness feature parameter is obtained through the difference between the second thickness sequence and the first thickness sequence; The battery substrate, the first electrode, and the second electrode are moving at a constant speed, and the arrangement direction of the first optical contour sensing array and the second optical contour sensing array is perpendicular to the moving direction of the battery substrate.

[0005] As one possible implementation, the optical contour sensing devices of the first optical contour sensing device array and the second optical contour sensing device array are non-contact. The acquisition lenses on both sides of the first optical contour sensing device array / second optical contour sensing device array face the two surfaces of the first surface electrode / second surface electrode. The optical contour sensing devices acquire data synchronously, and seamless field of view coverage in the coating width direction is achieved through the optical contour sensing device array.

[0006] As one possible implementation, comparing the first thickness characteristic parameter and the second thickness characteristic parameter with a preset threshold to determine whether there is an anomaly in the coating area of ​​the electrode includes the following steps: The characteristics of the coating thickness in the first coating thickness sequence are analyzed to obtain the first thickness characteristic parameter; wherein, the first coating thickness sequence is obtained by subtracting the first thickness sequence from the substrate thickness; The first thickness feature parameter is compared with the first preset thickness feature threshold. When the first thickness feature parameter exceeds the first preset thickness feature threshold, there is an abnormal first coating thickness at the corresponding position. The characteristics of the coating thickness in the second coating thickness sequence are analyzed to obtain the second thickness characteristic parameters; wherein, the second coating thickness sequence is obtained by subtracting the second thickness sequence from the first thickness sequence; The second thickness feature parameter is compared with the second preset thickness feature threshold. When the second thickness feature parameter exceeds the second preset thickness feature threshold, there is an abnormality in the second coating thickness at the corresponding position.

[0007] As one possible implementation, the first thickness characteristic parameter and the second thickness characteristic parameter include at least the thinning width, the average slope of the thinning area, and the thickness ratio at a specified location. Obtaining the thickness characteristic parameters includes the following steps: Based on the first coating thickness sequence / second coating thickness sequence, the start and end positions of the thinning region are obtained; The difference between the start and end positions of the thinning region is calculated to obtain the thinning width. The average slope of the thinned region is obtained by dividing the difference in thinning thickness and the thinning width; wherein, the difference in thinning thickness is the difference in coating thickness between the start and end positions of the thinning region; The specified location thickness ratio is the ratio of the thickness of the specified location in the thinned area to the thickness of the normal area.

[0008] As one possible implementation, obtaining the start and end positions of the thinning region based on the first coating thickness sequence / second coating thickness sequence includes the following steps: Based on the first coating thickness sequence / the second coating thickness sequence, a thickness change slope sequence is obtained; When the absolute value of the thickness change slope in the thickness change slope sequence is greater than the first preset slope threshold, the corresponding position is the starting position of the thinning region; When the absolute value of the thickness change slope of a consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of thinning area is the end position of the thinning area. The thickness change slope sequence is expressed as: thickness change slope = ∆Z / ∆X, where Z represents the coating thickness in the first coating thickness sequence / second coating thickness sequence, and X represents the coating position in the first coating thickness sequence / second coating thickness sequence.

[0009] As one possible implementation, the detection method further includes the following steps: before obtaining the second coating thickness sequence, removing sequences in the second thickness sequence and the first thickness sequence that correspond to the positions of the first coating thickness abnormalities.

[0010] As one possible implementation, the detection method further includes a first weighing device and a second weighing device; The first weighing device is used to obtain the weight of the first electrode sheet when the coating start position is detected, and to obtain the first weight sequence; The second weighing device is used to obtain the weight of the second electrode when the coating start position is identified, and to obtain the second weight sequence.

[0011] As one possible implementation, the detection method further includes comparing a first weight sequence, a second weight sequence, a first thickness feature parameter, and a second thickness feature parameter with a preset threshold to determine whether there are any abnormalities in the coating area of ​​the substrate, specifically: When the coating weight in the first coating weight sequence exceeds the first preset coating weight threshold, there is a first coating weight anomaly at the corresponding position; wherein, the first coating weight sequence is obtained by subtracting the first weight sequence from the substrate weight; When the coating weight in the second coating weight sequence exceeds the second preset coating weight threshold, there is a second coating weight anomaly at the corresponding position; wherein, the second coating weight sequence is obtained by subtracting the second weight sequence from the first weight sequence; The first thickness feature parameter is compared with the first preset thickness feature threshold. When the first thickness feature parameter exceeds the first preset thickness feature threshold, there is an abnormal first coating thickness at the corresponding position. The second thickness feature parameter is compared with the second preset thickness feature threshold. When the second thickness feature parameter exceeds the second preset thickness feature threshold, there is an abnormality in the second coating thickness at the corresponding position.

[0012] As one possible implementation method, the detection method further includes the following steps: Before obtaining the second coating weight sequence, data corresponding to abnormal positions of the first coating weight in the second weight sequence and the first weight sequence are removed. Before obtaining the first thickness feature parameter, the sequences corresponding to the positions of the first coating weight abnormality or the second coating weight abnormality in the first thickness sequence are removed. Before obtaining the second thickness feature parameters, sequences corresponding to the positions of the first coating weight abnormality, the second coating weight abnormality, or the first coating thickness abnormality in the second thickness sequence and the first thickness sequence are removed.

[0013] A battery electrode coating anomaly detection system based on double-sided thickness is used to implement the method described in any one of the above-mentioned methods. The system includes a first coating module, a first thickness detection module, a second coating module, a second thickness detection module, and an anomaly analysis module. The first coating module is used to coat and dry the first surface of the battery substrate to obtain the first electrode sheet; The first thickness detection module is used to mark the coating start position, and at the same time, based on the first optical contour sensing device array, it obtains the height contour of the first surface electrode and performs preprocessing to obtain the first thickness sequence. The second coating module is used to coat and dry the second surface of the battery substrate of the first electrode to obtain the second electrode. The second thickness detection module is used to obtain the height profile of the second electrode sheet and perform preprocessing based on the second optical profile sensing device array when the coating start position is identified, so as to obtain the second thickness sequence. The anomaly analysis module is used to compare the first thickness feature parameter and the second thickness feature parameter with a preset threshold to determine whether there is an anomaly in the coating area of ​​the electrode; wherein, the first thickness feature parameter is obtained through a first thickness sequence, and the second thickness feature parameter is obtained through the difference between the second thickness sequence and the first thickness sequence; The battery substrate, the first electrode, and the second electrode are moving at a constant speed, and the arrangement direction of the first optical contour sensing array and the second optical contour sensing array is perpendicular to the moving direction of the battery substrate.

[0014] This invention provides a method and system for detecting abnormalities in battery electrode coating based on double-sided thickness, offering significant technical advantages. The invention arranges an array of optical contour sensors along the coating width direction to scan the uniformly moving surface of the coated electrode. This array can non-contactly measure the complete lateral height contour line in real time, acquiring micron-level height information. By combining simultaneous scanning by multiple contour sensors with the electrode conveyor belt movement, a "matrix" data acquisition is formed, ultimately generating thickness matrix data for the entire coating area of ​​the electrode. This achieves seamless lateral coverage and continuous longitudinal measurement of the electrode coating area. The method of this invention can monitor the coating quality of the entire area of ​​the first and second surfaces of the electrode in real time, especially the coating quality of the thinned areas. It allows for full inspection of the electrode coating area under high-speed production conditions, avoiding the lag of offline detection and eliminating production defects caused by offline detection delays. The data can then be fed back to the control system, providing a prerequisite for closed-loop control of process parameters. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart illustrating an embodiment of the method of the present invention; Figure 2 This is a schematic diagram of the installation layout of the method embodiment of the present invention on the coating production line; Figure 3 This is a schematic cross-sectional view of the first electrode sheet of the present invention along the coating width direction; Figure 4 This is a top view of the first optical contour sensing device array of the present invention detecting the thickness of the first surface electrode. Figure 5 This is a front view of the first optical contour sensing device array of the present invention detecting the thickness of the first surface electrode. Figure 6 This is a schematic cross-sectional view of the second electrode sheet of the present invention along the coating width direction; Figure 7 This is a data distribution diagram of the first coating thickness sequence of the present invention; Figure 8 This is an overall schematic diagram of an embodiment of the system of the present invention; Explanation of reference numerals in the attached figures: 100. Substrate; 101. First coating die; 102. Second coating die; 201. First weighing device; 202. Second weighing device; 301. First optical profile sensor array; 302. Second optical profile sensor array; 401. First drying device; 402. Second drying device; 501. Marking device; 502. First mark recognition device; 503. Second mark recognition device; 504. Third mark recognition device; 110. Normal thickness area; 120. Thinning area; 601. First coating module; 602. First thickness detection module; 603. Second coating module; 604. Second thickness detection module; 605. Anomaly analysis module. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to embodiments. These embodiments are illustrative of the invention and the invention is not limited thereto. Unless otherwise specified, the features in the following embodiments can be combined with each other.

[0018] Example 1: In one embodiment, such as Figure 1 and Figure 2 As shown, Figure 1 This is a flowchart illustrating an embodiment of the method of the present invention. Figure 2 This is a schematic diagram of the installation and layout of the detection method in this embodiment on the coating production line. A method for detecting abnormalities in battery electrode coating based on double-sided thickness includes the following steps: S100: Coating and drying the first surface of the battery substrate to obtain the first electrode sheet. Specifically, the substrate 100 comes out from the unwinding shaft and is carried by a conveyor belt. The substrate passes through the first coating die 101, which coats the slurry onto the first surface of the substrate 100. After drying by the first drying device 401, a single-sided coated substrate, i.e., the first electrode sheet, is obtained.

[0019] S200: Mark the coating start position, and at the same time, based on the first optical contour sensing device array, obtain the height contour of the first electrode sheet and perform preprocessing to obtain the first thickness sequence. Specifically, the marking device 501 marks the coating start position, and at the same time, the first optical contour sensing device array 301 starts scanning the contour of the first electrode sheet, collects the original height contour data of the first electrode sheet at different positions, and obtains the first thickness sequence after preprocessing.

[0020] S300: Coating and drying are performed on the second surface of the battery substrate of the first electrode to obtain the second electrode. Specifically, the substrate continues to be conveyed, and the second coating die 102 coats the second surface of the substrate of the first electrode. After drying by the second drying device 402, a double-coated substrate, namely the second electrode, is obtained. The first surface and the second surface are two opposite surfaces of the substrate.

[0021] S400: When the coating start position is identified, the height profile of the second electrode sheet is obtained and preprocessed based on the second optical profile sensing device array to obtain the second thickness sequence. Specifically, when the first mark recognition device 502 identifies the coating start position, the second optical profile sensing device array 302 scans the profile of the second electrode sheet, collects the original height profile data of the second electrode sheet, and obtains the second thickness sequence after preprocessing.

[0022] S500: Compare the first thickness feature parameter and the second thickness feature parameter with a preset threshold to determine whether there is an abnormality in the coating area of ​​the electrode; wherein, the first thickness feature parameter is obtained through a first thickness sequence, and the second thickness feature parameter is obtained through the difference between the second thickness sequence and the first thickness sequence; The battery substrate, the first electrode, and the second electrode are moving at a constant speed, and the arrangement direction of the first optical contour sensing array and the second optical contour sensing array is perpendicular to the moving direction of the battery substrate.

[0023] In S100, a coating is applied to the first surface of the battery substrate and then dried to obtain the first electrode sheet. During coating of the substrate, the feeding system delivers slurry into the die and gasket system of the coating head. The slurry is extruded onto the substrate under pressure. The amount of slurry used in the thinning zone is controlled by the chamfering of the gasket in the coating head. The coating die simultaneously coats both the thinned and normal thickness zones (non-thinned zones), ensuring a close connection between the thinned and normal thickness zones. Figure 3 The diagram shows a cross-sectional view of the first electrode sheet along the coating width direction. Two thinning regions 120 are located on either side of the normal thickness region 110 and are closely connected to it. It should be noted that the coating die can coat one thinning region-normal thickness region-thinning region at a time, or it can coat multiple regions at once. This invention does not impose any limitations, as long as the configured contour sensing array can detect the entire coating width.

[0024] In another embodiment, in S200, the coating start position is marked, and the height profile of the first electrode is acquired and preprocessed based on the first optical profile sensing array to obtain the first thickness sequence, including the following steps: (1) Mark the starting position of the coating.

[0025] The coating start position is the location where coating just begins. Marking the coating start position allows the coating thickness of the first surface to correspond positionally with the coating thickness of the second surface. However, in practical applications, the first part of the electrode is often discarded. Therefore, to save computational resources, the coating start position can be selected from the location of the tab, which can be marked using a tab marking mechanism.

[0026] (2) While marking the starting position of coating, the height profile of different positions of the first surface electrode is obtained based on the first optical profile sensing device array to obtain the first original height sequence.

[0027] The first optical contour sensing device array is set up, such as Figure 4 and Figure 5 As shown, Figure 4 and Figure 5 These are top and front views of the first optical profile sensing array 301 detecting the thickness of the first electrode sheet. The substrate advancing direction is the coating length direction, also known as the machine direction. The coating width direction is perpendicular to the substrate advancing direction and is the direction from the uncoated area to the coated area. Therefore, the optical profile sensing array is arranged along the coating width direction.

[0028] The first optical contour sensing device has symmetrically arranged acquisition lenses on both sides, facing the first and second surfaces of the first electrode sheet respectively. The angle between the central axis of the acquisition lens and the normal to the first / second surface is 0°~45°, where the angle is 0° and the acquisition lens is perpendicular to the first / second surface. The distance between the lens and the substrate surface is 80~100mm. A sensing array is formed by multiple sensing devices. The single-sided sensing array achieves seamless field-of-view coverage in the coating width direction, enabling simultaneous imaging of the same position on both sides of the electrode sheet, and thus synthesizing the entire height contour of that position. Data acquisition is synchronously triggered by a data acquisition card to acquire data from all sensing devices. Since the substrate is moving, the sensing array can acquire the height contour of the first electrode sheet at different positions. Since the substrate / first electrode sheet is in continuous conveying, the height contour data of different positions of the first electrode sheet can be detected, i.e., the first original height sequence. The order of these sequences represents their positions on the first electrode sheet. The resulting first original height sequence is data obtained by seamlessly covering the coating area of ​​the first surface electrode from the coating start position and measuring continuously in the longitudinal direction. The optical contour sensing array used in this invention obtains "matrix-style" full-inspection data, which provides more accurate basic data compared to the existing "Z"-shaped intermittent scanning mode performed by a single sensing device.

[0029] In another embodiment, a non-contact high-precision optical profile measurement sensor array can be used, and a laser confocal displacement sensor can be selected, with a measurement accuracy of ±1μm, which can more accurately detect the coating thickness.

[0030] (3) The first original height sequence is filtered and denoised and the belt jitter is compensated to obtain the first thickness sequence.

[0031] The raw data obtained from the sensor array contains numerous interference signals, including high-frequency random noise and system motion errors caused by belt jitter, which need to be removed. Low-pass filters such as Gaussian filters or moving average filters can be used to remove high-frequency random noise, preserving low-frequency signals that characterize the true contour features and motion errors. Belt jitter is a low-frequency, global reference plane fluctuation; it can be estimated and fitted using methods such as baseline fitting, and then subtracted from the signal. By eliminating high-frequency random noise and low-frequency system motion errors, stable and reliable height contour information of the first electrode surface can be reconstructed. The first thickness sequence is the sum of the coating thickness (after drying) of the first surface of the substrate and the substrate thickness.

[0032] In S300, a coating is applied to the second surface of the battery substrate of the first electrode and then dried to obtain the second electrode, as shown below. Figure 6 As shown, this is a cross-sectional schematic diagram of the second electrode along the coating width direction. The coatings on the first and second surfaces of the substrate can correspond one-to-one.

[0033] In S400, when the coating start position is identified, the height profile of the second electrode is acquired based on the second optical profile sensing array and preprocessed to obtain the second thickness sequence, including the following steps: (1) When the coating start position is identified, the height profile of different positions of the second surface electrode is obtained based on the second optical contour sensing device array to obtain the second original height sequence. When the coating start position is identified, the detection is performed so that the coating thickness of the first surface electrode and the second surface electrode can be matched one-to-one in position, so that the coating thickness of the individual second surface can be calculated.

[0034] (2) The second original height sequence is filtered and noise reduced and belt jitter compensated to obtain the second thickness sequence. This part of the processing is the same as the processing of the first electrode detection data, and will not be described again. The second thickness sequence is the sum of the coating thickness of the first surface of the substrate (after drying), the coating thickness of the second surface (after drying), and the substrate thickness.

[0035] In another embodiment, in S500, the first thickness characteristic parameter and the second thickness characteristic parameter are compared with a preset threshold to determine whether there is an abnormality in the coating area of ​​the electrode, including the following steps: S510: Analyze the characteristics of the coating thickness in the first coating thickness sequence to obtain the first thickness characteristic parameter; wherein, the first coating thickness sequence is obtained by subtracting the first thickness sequence from the substrate thickness, specifically including: (1) The first thickness sequence and the substrate thickness are subtracted to obtain the first coating thickness sequence.

[0036] Coating thickness = Fixed height of opposing sensor - Distance from sensor to electrode - Substrate thickness. The fixed height of the opposing sensor is determined when setting up the optical contour sensor array. The distance from sensor to electrode is the thickness data in the first thickness sequence / second thickness sequence. The thickness of the uncoated substrate is measured using a thickness gauge, and the average of multiple measurements is taken as the general substrate thickness. The first thickness is the total thickness of the coating thickness and the substrate thickness. The difference between the first thickness sequence and the substrate thickness is calculated to obtain the first coating thickness sequence, which represents the coating thickness of the first surface of the substrate.

[0037] (2) Based on the first coating thickness sequence, the start and end positions of the first surface thinning region are obtained. like Figure 7 The diagram described is a thickness diagram of a cross-section of the coating area along the coating width direction, i.e., a data distribution diagram of a first coating thickness sequence. The Z-axis represents the coating thickness (after drying), and the X-axis represents the position along the coating width direction. These data can be obtained by processing data collected by the optical contour sensing array. Along the X-axis, the coating areas are sequentially designated as the first thinning area, the normal thickness area, and the second thinning area. ∆Z / ∆X represents the thickness change slope. The thickness change slope of the normal thickness area is zero, while the thickness change slope of the thinning area is constantly changing. Taking the first thinning area as an example, from the starting position to the ending position, the thickness change slope of the first thinning area gradually changes from +∞ to close to zero (a positive number). Therefore, for the first thinning area: at the boundary between the uncoated area and the coated area, the coating thickness undergoes a sudden change, meaning ∆Z / ∆X approaches infinity (greater than a first preset slope threshold, for example, greater than 10). 3 When the coating thickness changes extremely little, that is, when ∆Z / ∆X is close to zero (less than the second preset slope threshold, for example, less than 10), it is the starting position of the first thinning region; when the coating thickness changes extremely little, that is, when ∆Z / ∆X is close to zero (less than the second preset slope threshold, for example, less than 10), it is the starting position of the first thinning region. -3When the first thinning region ends, the point where ∆Z / ∆X approaches zero is determined. Furthermore, to eliminate interference from abnormal coating, the first point approaching zero is identified as the end position when N consecutive points (e.g., 20) have ∆Z / ∆X values ​​close to zero. The thickness change slope of the second thinning region at both the start and end positions gradually changes from zero (negative) to close to -∞. Its calculation method is similar to that of the first thinning region and will not be repeated here.

[0038] In this embodiment, the starting and ending positions of the thinning area are determined by the slope of the thickness change, which solves the error problem caused by the reliance on manual and subjective judgment in existing methods, and has the technical advantages of automation, objectivity and high repeatability.

[0039] (3) Based on the start and end positions of the first surface thinning region, a first thickness characteristic parameter is obtained to characterize the coating situation of the first surface. The first thickness characteristic parameter includes at least the first thinning width, the average slope of the first thinning region, and the thickness ratio at the first specified position.

[0040] Thinning width = |End position -Starting position|.

[0041] Thinning thickness difference = |thickness at the end position - thickness at the beginning position|.

[0042] Average slope of the thinned area = difference in thinning thickness / thinning width.

[0043] The specified location thickness ratio = thickness of the thinned region at the specified location / thickness of the normal region. The specified location of the thinned region refers to certain special positions along the thinning width direction, such as one-quarter, one-half, and three-quarters of the thinning width. The thickness of the thinned region of the battery electrode should be a convex curve; therefore, the specified location thickness ratio at any position in the thinned region should be greater than the average slope of the thinned region.

[0044] S520: Compare the first thickness feature parameter with the first preset thickness feature threshold. When the first thickness feature parameter exceeds the first preset thickness feature threshold, an anomaly in the first coating thickness exists at the corresponding location, and the location of the anomaly in the first coating thickness is marked. The first preset thickness feature threshold corresponds to the first thickness feature parameter and includes at least a first thinning width threshold, a first slope threshold, and several first thickness ratio thresholds. The specific thresholds can be determined based on the thickness data of the thinned area actually measured.

[0045] S530: Analyze the characteristics of the coating thickness in the second coating thickness sequence to obtain the second thickness characteristic parameter; wherein, the second coating thickness sequence is obtained by subtracting the second thickness sequence from the first thickness sequence.

[0046] (1) The second coating thickness sequence is obtained by subtracting the second thickness sequence and the first thickness sequence.

[0047] The second thickness sequence is the thickness of the second electrode sheet, which is the first surface coating thickness + substrate thickness + second surface coating thickness. The first thickness sequence and the second thickness sequence are the thicknesses at the same position. Therefore, by subtracting the second thickness sequence from the first thickness sequence, we can obtain the second coating thickness sequence, which represents the coating thickness of the second surface of the substrate.

[0048] (2) Based on the first coating thickness sequence, obtain the start and end positions of the second surface thinning region; based on the start and end positions of the second surface thinning region, obtain the second thickness characteristic parameters, which include at least the second thinning width, the average slope of the second thinning region, and the thickness ratio at the second specified position. The processing method for this part is the same as that for the first surface data, and will not be described again here.

[0049] In another embodiment, when obtaining the second thickness feature parameter, data corresponding to positions with abnormal first coating thickness in both the second and first thickness sequences can be removed before obtaining the second coating thickness sequence. That is, after identifying an abnormal coating thickness on the first surface, it is no longer necessary to determine whether there is an abnormal coating thickness at the corresponding position on the second surface, thus saving computational resources. However, if the abnormal coating thickness is not removed, it can be further determined whether abnormal coating thickness exists on both sides. In practical applications, the choice can be made according to actual needs, and this invention does not impose any limitations.

[0050] S540: Compare the second thickness feature parameter with the second preset thickness feature threshold. If the second thickness feature parameter exceeds the second preset thickness feature threshold, an anomaly in the second coating thickness is detected at the corresponding location, and the location of the anomaly is marked. The first preset thickness feature threshold and the second preset thickness feature threshold can be set according to the actual situation; they can be the same or different.

[0051] In another embodiment, such as Figure 2 As shown, it also includes the following steps: (1) After step S200 and before step S300, when the second mark recognition device 503 recognizes the coating start position, the weight of the first electrode sheet is measured by the first weighing device 201. Since the substrate is always in the conveyor belt state, the weight at different positions in the conveyor belt direction of the first electrode sheet can be obtained, thereby obtaining the first weight sequence. The first weighing device is used to measure the weight of the first electrode sheet of a fixed length, which is the first weight, which is the sum of the coating weight of the first surface and the weight of the substrate. Since the weight of the fixed length of the substrate can be measured in advance, the difference between the first weight and the weight of this section of substrate is the weight of the slurry applied (after drying). The result of dividing the slurry weight by the length is the linear density of the dried slurry.

[0052] (2) After step S300 and before step S500, when the third mark recognition device 504 recognizes the coating start position, the second weighing device 202 starts to measure the weight of the second electrode sheet, obtains the weight measured at different positions on the second electrode sheet, and then obtains the second weight sequence. The second weight is the weight after both surfaces of the substrate are coated and dried, and is the sum of the coating weight of the first surface, the coating weight of the second surface, and the weight of the substrate.

[0053] It should be noted that all the above measurement steps were performed with the substrate / first electrode / second electrode running at a constant speed.

[0054] In another embodiment, the method further includes: comparing a first weight sequence, a second weight sequence, a first thickness feature parameter, and a second thickness feature parameter with a preset threshold to determine whether there are any abnormalities in the coating area of ​​the substrate, specifically: (1) When the coating weight in the first coating weight sequence exceeds the first preset coating weight threshold, there is a first coating weight abnormality at the corresponding position; wherein, the first coating weight sequence is obtained by subtracting the first weight sequence from the substrate weight, and the first coating weight abnormality refers to the abnormality of the slurry weight coated on the first surface of the substrate.

[0055] (2) When the coating weight in the second coating weight sequence exceeds the second preset coating weight threshold, a second coating weight anomaly exists at the corresponding position; wherein, the second coating weight sequence is obtained by subtracting the second weight sequence from the first weight sequence, and the second coating weight anomaly refers to an anomaly in the weight of the slurry coated on the second surface of the substrate. Before this step, the positions of coating weight anomalies can be removed from the second weight sequence, so that the positions of first surface coating weight anomalies (first coating weight anomalies) will no longer be detected, thereby saving computational resources. Of course, they can also be left unremoved, which can further clarify whether anomalies exist on both sides.

[0056] In this invention, coating anomalies include at least coating weight anomalies (first coating weight anomaly and second coating weight anomaly) and coating thickness anomalies (first coating thickness anomaly and second coating thickness anomaly). Coating weight anomalies are caused by the slurry weight exceeding a reasonable range, which is the root cause of coating anomalies. If the slurry weight is abnormal, it will inevitably cause coating thickness anomalies. Coating thickness anomalies are caused by a series of indicators measuring coating thickness exceeding a reasonable range. Coating thickness anomalies are a result of coating anomalies and may be caused by slurry weight anomalies or equipment issues such as coating dies. When analyzing whether coating anomalies exist, the judgment is first based on the slurry weight. Because if the weight is not within a preset weight threshold range, the final coating thickness will inevitably be abnormal regardless of the coating method. Compared to thickness data, weight data is much less abundant, which can greatly save computational resources and thus improve computational efficiency.

[0057] (3) Compare the first thickness feature parameter with the first preset thickness feature threshold. When the first thickness feature parameter exceeds the first preset thickness feature threshold, there is a first coating thickness anomaly at the corresponding position. Before this step, the sequence corresponding to the position of the coating weight anomaly (first coating weight anomaly or second coating weight anomaly) identified based on weight can be removed from the first thickness sequence to further save computing resources. The premise for this processing is that the weight sequence and the thickness sequence must be able to correspond one-to-one in position. This can be achieved by setting the same sampling frequency for the weighing device and the optical contour sensing device, or by other means. These are conventional methods that can be handled by those skilled in the art, and will not be elaborated in this application. Of course, the thickness sequence with weight anomalies can also be left unremoved. This can further clarify whether the source of the anomaly is the weight of the slurry (fundamental problem) or the coating method (process problem). Furthermore, different labels can be marked for all slurry weight anomalies and all coating process anomalies to help analyze the cause of the anomaly in the future.

[0058] (4) Compare the second thickness feature parameter with the second preset thickness feature threshold. If the second thickness feature parameter exceeds the second preset thickness feature threshold, then there is a second coating thickness anomaly at the corresponding position. Before this step, all the coating anomalies (first coating weight anomaly, second coating weight anomaly, first coating thickness anomaly) that have been identified can be removed from the second thickness sequence and the first thickness sequence to save computational resources. Of course, they can also be left unremoved, which can further clarify whether coating thickness anomalies exist on both sides. Furthermore, the first coating weight anomaly, the second coating weight anomaly, the first coating thickness anomaly, and the second coating thickness anomaly can be marked with different identifiers to help analyze the cause of the anomaly later.

[0059] In another embodiment, the aforementioned positions are relative positions on the substrate or electrode. A high-precision encoder can also be used to acquire the real-time linear velocity of the substrate / electrode, thereby determining the actual physical position of each data point or sequence on the electrode. The substrate, single-sided coated substrate, and double-sided coated substrate are driven by a main drive roller coupling, typically moving at a uniform speed. The sampling frequency of the optical profile sensing array is locked to the encoder pulse (e.g., sampling once every 10 micrometers), ensuring that the data from all sensing devices are not only synchronized in time but also precisely correlated in spatial displacement. This allows for the precise binding of each set of thickness data acquired by the high-precision optical profile measurement sensing array to the physical position on the substrate, providing a fundamental basis for the point-to-point data analysis and separate analysis of the coating condition on the second surface of the substrate in this application.

[0060] In another embodiment, a third optical profile sensing array and a third weighing device can be added after the substrate is coated and before drying, and a fourth optical profile sensing array and a fourth weighing device can be added after the first electrode is coated and before drying to collect the thickness and weight of the slurry in the undried state, so as to achieve full coverage detection and monitoring of the process.

[0061] In another embodiment, the collected first weight, second weight, and extracted thickness feature parameters are fed back to the HMI interface and compared with a preset threshold range. If any of them exceed the preset threshold range, it is determined that there is a coating abnormality at that location, an alarm signal is generated, and an adjustment command is sent to the coating machine or coating die head control system through the communication interface. This provides a system interface for forming a fully automatic closed-loop quality control, which goes beyond the passive monitoring mode that can only alarm.

[0062] The detection method of any of the above embodiments can be used for coating detection of electrode sheets such as lithium battery electrodes, sodium-ion batteries, and solid-state batteries.

[0063] Example 2 To further illustrate the effectiveness of this testing system, based on the parameter settings and acceptable range in Example 1, the following experiment was conducted: online detection was performed on the thinned areas of a batch of coated electrode sheets to obtain a series of thickness characteristic parameters. Based on the detection results, the electrode sheets were divided into two categories: acceptable and unacceptable. Subsequently, these two types of electrode sheets were respectively fabricated into battery cells, and the key interface characteristics of the battery cells were tested. The electrode sheet detection results, thickness characteristic parameters, and battery cell test results are shown in Table 1.

[0064] Table 1. Comparison of Electrode Test Results, Thickness Characteristic Parameters, and Cell Test Results

[0065] As shown in the table above, the qualified thinned electrode sheets detected and judged by the method provided by this invention produce cells with good interface performance. Conversely, all kinds of unqualified thinned electrode sheets detected will cause problems in the subsequent cell interface, directly leading to cell performance loss or safety hazards.

[0066] This result fully demonstrates the accuracy, effectiveness, and industrial applicability of the detection method described in this invention. By identifying and removing substandard thinned electrode sheets online in real time, cell failures caused by coating defects can be prevented at the source, significantly improving the production yield, consistency, and safety of power batteries.

[0067] Example 3: A battery electrode coating anomaly detection system based on double-sided thickness, such as Figure 8 As shown, to implement any of the above embodiments, the system includes a first coating module 601, a first thickness detection module 602, a second coating module 603, a second thickness detection module 604, and an anomaly analysis module 605; The first coating module 601 is used to coat and dry the first surface of the battery substrate to obtain the first electrode sheet; The first thickness detection module 602 is used to mark the coating start position, and at the same time, based on the first optical contour sensing device array, it obtains the height contour of the first surface electrode and performs preprocessing to obtain the first thickness sequence. The second coating module 603 is used to coat and dry the second surface of the battery substrate of the first electrode to obtain the second electrode. The second thickness detection module 604 is used to obtain the height profile of the second electrode sheet and perform preprocessing based on the second optical profile sensing device array when the coating start position is identified, so as to obtain the second thickness sequence. The anomaly analysis module 605 is used to compare the first thickness feature parameter and the second thickness feature parameter with a preset threshold to determine whether there is an anomaly in the coating area of ​​the electrode; wherein, the first thickness feature parameter is obtained through a first thickness sequence, and the second thickness feature parameter is obtained through the difference between the second thickness sequence and the first thickness sequence; The battery substrate, the first electrode, and the second electrode are moving at a constant speed, and the arrangement direction of the first optical contour sensing array and the second optical contour sensing array is perpendicular to the moving direction of the battery substrate.

[0068] Various changes and modifications made without departing from the spirit and scope of this invention, and all equivalent technical solutions, also fall within the scope of this invention.

[0069] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0070] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, apparatus, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0071] This invention is described with reference to flowchart illustrations and / or block diagrams of the method, terminal device (system), and computer program product according to the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0072] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0073] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal equipment, causing a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0074] It should be noted that: The phrase "an embodiment" or "an embodiment" used in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" or "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0075] Furthermore, it should be noted that the shapes and names of the parts and components described in the specific embodiments described in this specification may differ. All equivalent or simple variations made to the structure, features, and principles described in this patent concept are included within the protection scope of this patent. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not depart from the structure of this invention or exceed the scope defined in these claims, they should all fall within the protection scope of this invention.

Claims

1. A method for detecting abnormal coating of battery electrode sheets based on double-sided thickness, characterized in that, Includes the following steps: The first surface of the battery substrate is coated and dried to obtain the first electrode sheet; The coating start position is marked, and the height profile of the first surface electrode is obtained and preprocessed based on the first optical profile sensing device array to obtain the first thickness sequence. The second electrode is obtained by coating and drying the second surface of the battery substrate of the first electrode. When the coating start position is identified, the height profile of the second surface electrode is obtained and preprocessed based on the second optical profile sensing device array to obtain the second thickness sequence. The first thickness feature parameter and the second thickness feature parameter are compared with a preset threshold to determine whether there is an anomaly in the coating area of ​​the electrode; wherein, the first thickness feature parameter is obtained through a first thickness sequence, and the second thickness feature parameter is obtained through the difference between the second thickness sequence and the first thickness sequence; The battery substrate, the first electrode, and the second electrode are moving at a constant speed, and the arrangement direction of the first optical contour sensing array and the second optical contour sensing array is perpendicular to the moving direction of the battery substrate.

2. The method according to claim 1, characterized in that, The optical contour sensing devices of the first optical contour sensing device array and the second optical contour sensing device array are non-contact. The acquisition lenses on both sides of the first optical contour sensing device array / the second optical contour sensing device array face the two surfaces of the first surface electrode / the second surface electrode. The optical contour sensing devices acquire data synchronously, and seamless field of view coverage in the coating width direction is achieved through the optical contour sensing device array.

3. The method according to claim 1, characterized in that, The step of comparing the first thickness feature parameter and the second thickness feature parameter with a preset threshold to determine whether there is an abnormality in the coating area of ​​the electrode includes the following steps: The characteristics of the coating thickness in the first coating thickness sequence are analyzed to obtain the first thickness characteristic parameter; wherein, the first coating thickness sequence is obtained by subtracting the first thickness sequence from the substrate thickness; The first thickness feature parameter is compared with the first preset thickness feature threshold. When the first thickness feature parameter exceeds the first preset thickness feature threshold, there is an abnormal first coating thickness at the corresponding position. The characteristics of the coating thickness in the second coating thickness sequence are analyzed to obtain the second thickness characteristic parameters; wherein, the second coating thickness sequence is obtained by subtracting the second thickness sequence from the first thickness sequence; The second thickness feature parameter is compared with the second preset thickness feature threshold. When the second thickness feature parameter exceeds the second preset thickness feature threshold, there is an abnormality in the second coating thickness at the corresponding position.

4. The method according to claim 3, characterized in that, The first thickness characteristic parameter and the second thickness characteristic parameter include at least the thinning width, the average slope of the thinning area, and the thickness ratio at a specified location. Obtaining the thickness characteristic parameter includes the following steps: Based on the first coating thickness sequence / second coating thickness sequence, the start and end positions of the thinning region are obtained; The difference between the start and end positions of the thinning region is calculated to obtain the thinning width. The average slope of the thinned region is obtained by dividing the difference in thinning thickness and the thinning width; wherein, the difference in thinning thickness is the difference in coating thickness between the start and end positions of the thinning region; The specified location thickness ratio is the ratio of the thickness of the specified location in the thinned area to the thickness of the normal area.

5. The method according to claim 4, characterized in that, The process of obtaining the start and end positions of the thinning region based on the first coating thickness sequence / second coating thickness sequence includes the following steps: Based on the first coating thickness sequence / the second coating thickness sequence, a thickness change slope sequence is obtained; When the absolute value of the thickness change slope in the thickness change slope sequence is greater than the first preset slope threshold, the corresponding position is the starting position of the thinning region; When the absolute value of the thickness change slope of a consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of consecutive preset number of thinning area is the end position of the thinning area. The thickness change slope sequence is expressed as: thickness change slope = ∆Z / ∆X, where Z represents the coating thickness in the first coating thickness sequence / second coating thickness sequence, and X represents the coating position in the first coating thickness sequence / second coating thickness sequence.

6. The method according to claim 3, characterized in that, It also includes the following steps: Before obtaining the second coating thickness sequence, sequences corresponding to abnormal positions of the first coating thickness in both the second and first thickness sequences are removed.

7. The method according to claim 1, characterized in that, It also includes a first weighing device and a second weighing device; The first weighing device is used to obtain the weight of the first electrode sheet when the coating start position is detected, and to obtain the first weight sequence; The second weighing device is used to obtain the weight of the second electrode when the coating start position is identified, and to obtain the second weight sequence.

8. The method according to claim 7, characterized in that, It also includes comparing the first weight sequence, the second weight sequence, the first thickness feature parameter, and the second thickness feature parameter with preset thresholds to determine whether there are any abnormalities in the coating area of ​​the substrate, specifically: When the coating weight in the first coating weight sequence exceeds the first preset coating weight threshold, there is a first coating weight anomaly at the corresponding position; wherein, the first coating weight sequence is obtained by subtracting the first weight sequence from the substrate weight; When the coating weight in the second coating weight sequence exceeds the second preset coating weight threshold, there is a second coating weight anomaly at the corresponding position; wherein, the second coating weight sequence is obtained by subtracting the second weight sequence from the first weight sequence; The first thickness feature parameter is compared with the first preset thickness feature threshold. When the first thickness feature parameter exceeds the first preset thickness feature threshold, there is an abnormal first coating thickness at the corresponding position. The second thickness feature parameter is compared with the second preset thickness feature threshold. When the second thickness feature parameter exceeds the second preset thickness feature threshold, there is an abnormality in the second coating thickness at the corresponding position.

9. The method according to claim 8, characterized in that, It also includes the following steps: Before obtaining the second coating weight sequence, data corresponding to abnormal positions of the first coating weight in the second weight sequence and the first weight sequence are removed. Before obtaining the first thickness feature parameter, the sequences corresponding to the positions of the first coating weight abnormality or the second coating weight abnormality in the first thickness sequence are removed. Before obtaining the second thickness feature parameters, sequences corresponding to the positions of the first coating weight abnormality, the second coating weight abnormality, or the first coating thickness abnormality in the second thickness sequence and the first thickness sequence are removed.

10. A battery electrode coating anomaly detection system based on double-sided thickness, used to implement the method as described in any one of claims 1 to 9, characterized in that, The system includes a first coating module, a first thickness detection module, a second coating module, a second thickness detection module, and an anomaly analysis module; The first coating module is used to coat and dry the first surface of the battery substrate to obtain the first electrode sheet; The first thickness detection module is used to mark the coating start position, and at the same time, based on the first optical contour sensing device array, it obtains the height contour of the first surface electrode and performs preprocessing to obtain the first thickness sequence. The second coating module is used to coat and dry the second surface of the battery substrate of the first electrode to obtain the second electrode. The second thickness detection module is used to obtain the height profile of the second electrode sheet and perform preprocessing based on the second optical profile sensing device array when the coating start position is identified, so as to obtain the second thickness sequence. The anomaly analysis module is used to compare the first thickness feature parameter and the second thickness feature parameter with a preset threshold to determine whether there is an anomaly in the coating area of ​​the electrode; wherein, the first thickness feature parameter is obtained through a first thickness sequence, and the second thickness feature parameter is obtained through the difference between the second thickness sequence and the first thickness sequence; The battery substrate, the first electrode, and the second electrode are moving at a constant speed, and the arrangement direction of the first optical contour sensing array and the second optical contour sensing array is perpendicular to the moving direction of the battery substrate.

Images