A sodium ion battery coated diaphragm end face quality detection evaluation system

Abstract

The present application relates to a kind of sodium ion battery coated diaphragm end face quality detection evaluation system, belong to sodium ion battery diaphragm quality detection technical field.The system includes end face image acquisition module, end face profile scanning module, defect identification classification module and end face quality comprehensive evaluation module, can also include result output and feedback module.The system is accurately obtained to the different layers of diaphragm with multiple light modes, and combined with profile scanning, the classification identification of each layer defect is realized in combination with macro and micro, then the quality quantization and automatic grading of diaphragm roll end face as a whole are realized by fusing multidimensional detection results.The present application solves the lack of existing technology for diaphragm roll end face all-around synchronous detection and defect classification identification system, and can realize the effective fusion of multidimensional detection results, and the accurate quantization and grade division of subsequent diaphragm quality can be linked to actual production, and can be widely applied to the quality quantization evaluation and grade determination of sodium ion battery coated diaphragm.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery separator quality testing technology, and in particular to a sodium-ion battery coated separator end face quality testing and evaluation system. Background Technology

[0002] The separator is one of the key internal components of a sodium-ion battery. In actual production, sodium-ion battery separators increasingly employ PVDF (polyvinylidene fluoride) + ceramic (such as Al2O3, boehmite, etc.) composite coatings to improve the separator's thermal stability, mechanical strength, and electrolyte wettability. However, the quality inspection of separators with composite coatings is more complex and stringent, posing greater challenges to their testing.

[0003] Currently, battery separator-related testing technologies mainly include defect type detection, flatness detection, peel strength detection, and wavy edge detection after separator coating. For example, patent application CN119151890A discloses an online wavy edge detection method for lithium-ion battery separator slitting, which uses a high-resolution industrial camera and image processing methods to identify the fluctuation amplitude and frequency of the separator edge to achieve wavy edge detection; patent application CN113030093A discloses a battery separator surface defect detection method, which identifies defects by comparing template images; patent application CN106841213A discloses a method for detecting surface defects of battery separator coating, which classifies defects by statistically analyzing the geometric shape, brightness, and other characteristic values ​​of surface defects; and patent application CN202582526U discloses a lithium-ion battery separator appearance inspection device, which uses a high-precision measuring probe to measure the flatness of the separator end face.

[0004] However, existing technologies still have the following shortcomings: First, although my country has issued its first group standard for separators used in sodium-ion batteries (T / CPPIA 54-2025), which specifies the requirements and test methods for separators used in sodium-ion batteries and applies to separators made from polyolefin resins, and can be used as a reference for coated polyolefin separators for sodium-ion batteries, this standard does not cover the testing and evaluation methods for the quality of the separator roll end face.

[0005] Second, existing technologies for quality inspection of coated diaphragms primarily target the membrane surface. While there are technologies for detecting wavy edges on the membrane, the essence of their implementation remains the analysis of membrane surface images. Therefore, existing technologies also lack the ability to inspect the quality of the coated diaphragm roll end face.

[0006] Third, existing technologies only cover the detection of a single defect type, such as wavy edges, and do not cover other end-face defects such as collapsed edges, warped edges, uneven end faces, interlayer slippage, cracking, uneven thickness, ceramic particle detachment, and PVDF coating omissions. At the same time, existing technologies are mostly simple measuring tools or defect identification devices, and lack a systematic detection and evaluation model that integrates multi-dimensional detection data of the coated diaphragm end face, calculates a comprehensive quality score, and classifies quality levels.

[0007] Fourth, although existing technologies have solved the problem of detecting missing coating on PVDF film surfaces, in end-face scenarios, due to the thin thickness and transparency of the PVDF coating, conventional transmission stations cannot complete the detection of the transparent PVDF coating on the end face. The detection of the transparent PVDF coating in end-face scenarios remains a technological gap.

[0008] Fifth, existing testing methods are mostly offline, which cannot achieve online end-face testing, let alone achieve closed-loop linkage with the upstream coating / slitting process control system.

[0009] In summary, the key technical problems that need to be solved are how to achieve online, all-round, synchronous inspection of the end face of the diaphragm roll, construct a defect classification system for the end face of the diaphragm roll coating, and effectively integrate multi-dimensional inspection results to accurately classify the diaphragm quality grade and link it with actual production. Summary of the Invention

[0010] In view of this, the present invention provides a sodium-ion battery coated separator end face quality inspection and evaluation system to solve the current technology's lack of comprehensive synchronous inspection of separator roll end face and separator roll coating layer end face defect classification system, as well as the lack of effective multi-dimensional detection result fusion of separator roll end face quality grading and quantitative standard, and even more so the lack of technical problems in linking quality evaluation results with actual production.

[0011] The present invention provides a sodium-ion battery coated separator end face quality inspection and evaluation system, comprising: The end face image acquisition module includes a camera submodule and a light source submodule. The camera submodule is set on one side of the target end face of the diaphragm roll to be detected. The light source submodule and the camera submodule cooperate to form a reflected light mode, a transmitted light mode and an oblique light mode, and the camera submodule acquires ceramic coating image, base film image and PVDF coating image respectively. The end face contour scanning module includes a radial scanning submodule, which scans along the radial direction of the target end face to acquire the target end face contour data; The defect identification and classification module includes an image processing submodule and a defect classification submodule. The image processing submodule extracts image features from the ceramic coating image, the base film image, and the PVDF coating image, respectively. The defect classification submodule completes the base film end-face defect identification and classification based on the image features of the base film image and the target end-face contour data. The defect classification submodule completes the coating end-face defect identification and classification based on the image features of the ceramic coating image and the PVDF coating image. The end-face quality comprehensive evaluation module is used to input the defect identification and classification results of the base film end face and the defect identification and classification results of the coating end face into a preset end-face quality comprehensive evaluation model to obtain a comprehensive score of the target end face, and to complete the classification of the quality level of the target end face based on the comprehensive score.

[0012] Furthermore, the light source submodule cooperates with the camera submodule to realize reflected light mode, transmitted light mode, and oblique light mode, including: In the reflected light mode, both the camera submodule and the light source submodule are located on one side of the target end face. The light emitted by the light source submodule illuminates the target end face at a first preset angle, and the camera submodule receives the light reflected from the target end face to obtain the ceramic coating image. In the transmitted light mode, the camera submodule is located on one side of the target end face, and the light source submodule is located on the opposite side of the target end face. The light emitted by the light source submodule penetrates the target end face along the axial direction of the diaphragm roll and is received by the camera submodule to obtain the base film image. In the oblique illumination mode, both the camera submodule and the light source submodule are located on one side of the target end face. The light emitted by the light source submodule illuminates the target end face at a second preset angle, and the camera submodule receives the light reflected from the target end face to obtain the PVDF coating image. The first preset angle is greater than the second preset angle.

[0013] Furthermore, the light source submodule also includes an ultraviolet light unit and a fluorescent filter. In the oblique light mode, the light source submodule emits ultraviolet light through the ultraviolet light unit and illuminates the target end face at the second preset angle. The camera submodule receives the ultraviolet light reflected from the target end face through the fluorescent filter to obtain the PVDF coating image.

[0014] Furthermore, the wavelength of the ultraviolet light is 365nm.

[0015] Furthermore, the end face image acquisition module is set after the winding station of the diaphragm slitting machine or at an independent detection station, and the camera sub-module includes a line scan camera or an area scan camera.

[0016] Furthermore, the image acquisition resolution of the end face image acquisition module is not less than 5μm / pixel, and the image acquisition frequency of the end face image acquisition module is linked to the conveyor speed of the diaphragm roll.

[0017] Furthermore, the end face contour scanning module also includes an axial movement submodule, which drives the radial scanning submodule to move along the axial direction of the diaphragm roll.

[0018] Furthermore, the radial scanning submodule is a laser contour sensor or a confocal displacement sensor, and the scanning accuracy of the radial scanning submodule is not less than 0.01 mm, and the sampling interval is not greater than 0.1 mm.

[0019] Furthermore, the end-face quality comprehensive evaluation model includes a dimensional scoring sub-model and a comprehensive scoring sub-model; The dimensional scoring sub-model is as follows: , , in, This indicates the quality score of the base film end face. This indicates the coating end face quality score. Indicates the first The index weight of each base film end face defect, Indicates the first The standardized score of each base film end-face defect under a pre-set quantitative scoring system. Indicates the first The index weight of each coating end face defect, Indicates the first The standardized score of each coating end face defect under a preset quantitative scoring system; The comprehensive scoring sub-model is as follows: , in, This represents the overall score of the target end face. This indicates the dimensional weights for the base film end-face quality score. This indicates the dimensional weights for the coating end-face quality score.

[0020] Furthermore, it also includes a result output and feedback module, which includes a display unit, a storage unit, and a feedback unit; The display unit is used to display the image of the target end face, defect markings, the comprehensive score, and the quality level in real time. The storage unit is used to establish a quality traceability file for the target end face; The feedback unit is used to feed back the evaluation results of the target end face to the coating / slitting process control system upstream of the diaphragm roll production, and automatically adjust the coating parameters or slitting parameters.

[0021] The advantages of this invention compared to the prior art are: This invention includes an end-face image acquisition module, an end-face contour scanning module, a defect identification and classification module, and an end-face quality comprehensive evaluation module. It may also include a result output and feedback module. The system uses multiple lighting modes to accurately acquire images of different layers of the separator, and combines contour scanning to achieve macroscopic and microscopic defect classification and identification of each layer. Then, it integrates multi-dimensional detection results to achieve overall quality quantification and automatic grading of the separator roll end face. This invention solves the lack of a comprehensive synchronous detection and defect classification system for separator roll end faces in existing technologies. It can effectively integrate multi-dimensional detection results and accurately quantify and grade the subsequent separator quality, linking it to actual production. It can be widely applied to the quality quantification evaluation and grading of coated separators for sodium-ion batteries. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, 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.

[0023] Figure 1 This is a structural block diagram of a sodium-ion battery coated separator end face quality detection and evaluation system provided in Embodiment 1 of the present invention. Detailed Implementation

[0024] To overcome the shortcomings of existing technologies, such as the lack of a defect classification system for the end face of coated separators in sodium-ion batteries, the single dimension of quality inspection for the end face of separators, the inability to accurately inspect the end face of PVDF transparent coating, the lack of a comprehensive quality evaluation model, and the disconnect between inspection and process control, this invention provides a quality inspection and evaluation system for the end face of coated separators in sodium-ion batteries, which is particularly suitable for the quality inspection and evaluation of the end face of separators with PVDF + ceramic composite coating.

[0025] To further illustrate the technical solution of the present invention, specific embodiments are described below.

[0026] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of the invention include a particular feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. Furthermore, a particular feature, structure, or characteristic in one or more embodiments may be combined in any suitable form, and the terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless otherwise specifically emphasized.

[0027] System Implementation Example: See Figure 1 This is a structural block diagram of a sodium-ion battery coated separator end-face quality detection and evaluation system provided in Embodiment 1 of the present invention, as shown in the figure. Figure 1 As shown, the system includes an end-face image acquisition module 11, an end-face contour scanning module 12, a defect identification and classification module 13, an end-face quality comprehensive evaluation module 14, and a result output and feedback module 15. It is easy to understand that the above modules in this quality inspection and evaluation system can be configured in a fixed spatial structure, or in a non-fixed spatial structure, provided that the necessary data lines, feedback lines, and control lines for full functionality are connected. The following is a detailed description of each module: The end face image acquisition module 11 includes a camera submodule and a light source submodule. The camera submodule is set on one side of the target end face of the diaphragm roll to be detected. The light source submodule and the camera submodule cooperate to form a reflected light mode, a transmitted light mode and an oblique light mode, and the camera submodule acquires the ceramic coating image, the base film image and the PVDF coating image respectively.

[0028] In the production process of sodium-ion battery coated separators, the coated separators are rolled into separator rolls. The end face of the separator rolls presents a concentric ring-shaped cross-section formed by hundreds to thousands of layers of separator material stacked along the winding direction. Each ring represents a complete separator layer (including the base film and coating layers on both sides), and the width of the ring is equal to the thickness of a single separator layer (typically 10-30 μm). Specifically, when the separator (including the base film and coating layers on both sides) is wound onto a core to form a separator roll, hundreds to thousands of layers of separator material can be seen concentrically distributed from the inner ring to the outer ring when viewed from the end face. Each concentric ring represents a separator layer, and the structure of this ring from the inside out is as follows: PVDF coating (ultra-thin transparent layer) → ceramic coating (thin layer) → base film (main layer) → ceramic coating → PVDF coating. Since the total thickness of a single-layer diaphragm is only 10-30μm (base membrane 5-25μm + ceramic coating 2-5μm×2 + PVDF coating 1-3μm×2), the width of each concentric ring is only 10-30μm.

[0029] The coating process involves applying a coating to the membrane surface (i.e., the upper and lower surfaces of the diaphragm). During coating, the coating slurry (ceramic slurry or PVDF slurry) naturally spreads to the cut edges (i.e., the end faces) of the diaphragm. Especially when the slurry viscosity is low or the coating speed is high, natural edge accumulation, overflow, or slurry dripping may occur at the edges. Therefore, the condition of the coating layer on the end faces (complete coverage, uniform thickness, presence of peeling, etc.) directly reflects the quality of the coating process.

[0030] To achieve comprehensive and accurate defect detection and quality evaluation of each layer on the end face of the coated separator of a sodium-ion battery, this invention employs a dual-perspective observation and judgment method, combining macroscopic and microscopic perspectives. The macroscopic perspective refers to the acquisition and analysis of a specific feature of the end face as a whole (such as the coverage of the PVDF coating on the end face, the degree of fluctuation in the radial profile of the end face, etc.), while the microscopic perspective refers to the identification and analysis of hundreds or even thousands of concentric circles of the base film or coating formed by the rolling on the end face.

[0031] To achieve at least microscopic-level identification and analysis, this embodiment first sets up an end-face image acquisition module, which includes a camera submodule and a light source submodule. The camera submodule is positioned on one side of the target end face of the diaphragm roll to be inspected, to acquire an image of the target end face. The camera submodule can be a high-resolution line scan camera or an area scan camera. The light source submodule can be a multi-mode light source system, including a coaxial light source, a ring light source, and a backlight source. The end-face image acquisition module can be set after the winding station of the diaphragm slitting machine, or it can be set at an independent inspection station, to acquire high-definition images of both ends of the diaphragm roll. For clarity, the end face currently being inspected is referred to as the target end face. It is easy to understand that the end-face image acquisition module usually also includes an image acquisition card.

[0032] Because the base film, PVDF coating, and ceramic coating in the commonly used PVDF (polyvinylidene fluoride) + ceramic (such as Al2O3, boehmite, etc.) composite coating of sodium-ion batteries have different optical properties, resulting in differences in the transmission, reflection, and refraction of light, this embodiment utilizes these differences in optical properties to set three light modes for the end-face image acquisition module. The light source submodule and the camera submodule work together to form the reflected light mode, the transmitted light mode, and the oblique light mode, respectively.

[0033] (1) Reflected light mode In this mode, the light source submodule and the camera submodule are set on the same side, both located on one side of the target end face, or in other words, directly in front of the target end face. The light emitted by the light source submodule illuminates the target end face at a first preset angle (preferably 15° to 45°), and the camera submodule receives the light reflected from the target end face to obtain the ceramic coating image.

[0034] Its working principle is as follows: The ceramic coating is a white or light-colored opaque material with high reflectivity. Under reflected light, the target end face appears bright white, and the boundary and coverage integrity of the ceramic coating in the radial width and circumferential direction of the end face can be clearly distinguished.

[0035] Radial coverage refers to the requirement that the ceramic coating and PVDF coating completely cover the width of the ring on the radial direction of the diaphragm end face (from the inner ring to the outer ring of the diaphragm roll). In other words, the width of each part of the ring where the coating is located must meet the production specification requirements. If the radial width of the coating layer is less than the width of the base film ring, it indicates that there is a defect of incomplete coverage / insufficient coating.

[0036] Circumferential coverage means that the coating layer needs to continuously cover the corresponding ring along the entire circumference of the diaphragm end face. In other words, the coating layer needs to exist continuously around the entire circumference. If there are gaps or breaks in the coating, it indicates that there are defects such as missed coating, insufficient coating, or cracking.

[0037] The objects to be inspected under this light mode are: the radial / circumferential coverage of the ceramic coating end face, interlayer delamination, circumferential cracking, and point pits formed by the shedding of ceramic particles.

[0038] Interlayer delamination refers to the appearance of interlayer gaps and localized lifting at the end face between the ceramic coating and the base film, or between the PVDF coating and the ceramic coating.

[0039] Cracking refers to the appearance of continuous fracture gaps in the coating layer along the circumferential direction of the end face; Insufficient coating / missed coating refers to a situation where the radial width of the coating layer (equivalent to the coating thickness on the film surface) is less than the width required by the production specifications, or there are local gaps in the circumferential direction.

[0040] (2) Transmitted light mode In this mode, the camera submodule is located on one side of the target end face, that is, directly in front of the target end face, while the light source submodule is located on the opposite side of the target end face, that is, on the other end face of the diaphragm roll that is not the target end face. At this time, the light emitted by the light source submodule penetrates the target end face along the axial direction of the diaphragm roll and is received by the camera submodule to obtain the base film image.

[0041] Its working principle is as follows: The base film is a semi-transparent polyolefin material with a certain degree of light transmittance. The ceramic coating in the coating layer has significantly lower light transmittance than the base film. Although the PVDF coating has better light transmittance than the base film, as mentioned above, the thickness of the PVDF coating is significantly less than the thickness of the base film layer. Therefore, the overall light transmittance of the base film is significantly greater than that of the PVDF coating. Since the overall light transmittance of the base film is much higher than that of the ceramic + PVDF composite coating layer, the transmitted light can highlight the outline of the base film. Thus, by using transmitted light to form concentric rings of alternating light and dark, the end face outline of a single-ring base film and the coverage of the coating layer can be identified.

[0042] The detection targets under this light mode are: wavy edges, collapsed edges, warped edges, uneven end faces, interlayer slippage, and other defects on the single-loop end face of the base film. Among them, uneven end face defects require further identification in conjunction with the subsequent end face contour scanning module; they are listed here in advance only for the sake of uniformity.

[0043] Among them, wavy edge / collapsed edge / curved edge refers to: unevenness, inward / outward collapse, or curling of the single-loop base film at the radial position of the end face, and irregular concentric rings; Uneven end faces refer to the following: after multiple turns of diaphragm are stacked, the overall end faces are not on the same plane perpendicular to the winding axis, and there is a height difference in some areas compared to the end face of the diaphragm roll. Interlayer slip refers to the circumferential / radial misalignment of adjacent membrane layers at their end faces, resulting in the displacement of concentric annular zones.

[0044] (3) Oblique light mode In this mode, the light source submodule and the camera submodule are set on the same side, both located on one side of the target end face, or in other words, directly in front of the target end face. The light emitted by the light source submodule illuminates the target end face at a second preset angle (preferably 5° to 15°) almost parallel to the target end face. The camera submodule receives the light reflected from the target end face and obtains the PVDF coating image.

[0045] Comparing the light angles in the aforementioned reflected light mode, it can be seen that the first preset angle is significantly larger than the second preset angle, thus forming a reflected light mode and an oblique light mode respectively.

[0046] Its working principle is as follows: The PVDF coating is transparent, and under normal vertical lighting, the difference in light intensity between the reflected light and the ceramic coating is small and difficult to distinguish; when oblique light shines on the almost parallel end face at an extremely low angle, a significant difference in refraction and reflection light intensity will be generated at the end face interface of the PVDF coating and the ceramic coating, forming a unique contour contrast, so that only the end face boundary of the PVDF coating can be clearly identified.

[0047] The objects to be inspected under this light mode are: the radial and circumferential coverage of the PVDF coating on the end face, defects such as circumferential missing coating, and insufficient radial coating thickness.

[0048] The characteristics of each defect mode are described above.

[0049] The three light source modes can operate by sequential switching: within a very short time (milliseconds), the reflected light mode, transmitted light mode, and oblique light mode are switched sequentially, and the camera simultaneously acquires three end-face images, obtaining images of the ceramic coating, the base film, and the PVDF coating, respectively. The image acquisition resolution is preferably no less than 5μm / pixel, and the acquisition frequency is linked to the diaphragm conveyor speed to ensure that the end-face images are free from stretching deformation.

[0050] Furthermore, to address the technical challenge of detecting PVDF transparent coatings on the end face, and to improve the accuracy of PVDF coating identification, in a preferred embodiment, the light source submodule further includes an ultraviolet light unit and a fluorescent filter. In the oblique illumination mode, the light source submodule emits ultraviolet light through the ultraviolet light unit and illuminates the target end face at the second preset angle. The camera submodule receives the ultraviolet light reflected from the target end face through the fluorescent filter to obtain an image of the PVDF coating.

[0051] The ultraviolet light unit is preferably an ultraviolet LED light source with a wavelength of 365nm. After it illuminates the target end face, the PVDF coating on the target end face can generate a blue fluorescence response under ultraviolet light excitation. At this time, a high-sensitivity camera, together with a fluorescence filter set in front of its lens, receives the ultraviolet light reflected from the target end face, and a more accurate PVDF coating image can be obtained. The PVDF covered area in the image shows bright fluorescence, and the uncovered area is a dark area. At this time, the image processing algorithm is used to calculate the PVDF coverage of the end face, and the accuracy can reach ±0.5%.

[0052] The end face contour scanning module 12 includes a radial scanning submodule, which scans along the radial direction of the target end face to acquire the target end face contour data.

[0053] The radial scanning submodule is preferably a laser profile sensor or a confocal displacement sensor. The scanning accuracy of the radial scanning submodule is not less than 0.01 mm and the sampling interval is not greater than 0.1 mm. It scans radially along the end face of the diaphragm roll to obtain the three-dimensional point cloud data of the end face profile.

[0054] As a further preferred embodiment, the end face contour scanning module 12 may also include an axial movement submodule. This axial movement submodule drives the radial scanning submodule to move along the axial direction of the diaphragm roll, ensuring that the radial scanning submodule completely covers the full width of the diaphragm roll end face. The axial movement submodule can be a linear module or a lead screw mechanism. Therefore, the end face contour scanning module 12 in this case actually has two directions of movement: Radial scanning (main scanning direction): The laser profile sensor emits a linear laser along the radial direction (from the center of the diaphragm roll to the edge) of the diaphragm roll end face, acquiring the three-dimensional coordinate data of all points on a radial line on the end face in one go. This is the main scanning direction for acquiring end face profile data. It is easy to understand that in other embodiments, the diaphragm roll can also be configured to rotate along its axis to achieve scanning of multiple different radial paths, corresponding to acquiring multiple radial three-dimensional coordinate data.

[0055] Axial movement (auxiliary feed direction): The laser profile sensor is mounted via a linear module or lead screw mechanism, allowing for micro-feeding along the axial direction (i.e., perpendicular to the end face) of the diaphragm roll. This is because the end face positions of different membrane rolls may vary (e.g., different roll widths, installation position deviations, etc.). The axial movement function enables the sensor to automatically focus and adapt to different membrane roll specifications, ensuring that the sensor is always at the optimal working distance.

[0056] The 3D point cloud data acquired by the laser contour sensor can simultaneously reflect the contour features of the base film end face and the thickness distribution of the coating layer end face (by comparing the contour height difference between the coated and uncoated areas). The laser contour sensor achieves macroscopic overall contour detection, verifying the overall flatness of the end face (end face unevenness) and large-scale edge collapse and warping; the camera sensing in multi-light mode achieves microscopic layered defect identification of single-circle concentric rings, and the two form a complementary macroscopic and microscopic detection. That is, this invention adopts a detection logic that combines microscopic fine identification with macroscopic overall verification: high-resolution (5μm / pixel accuracy or higher) camera sensing in multi-light mode is used to microscopically identify minute defects in single-circle rings, while the laser contour sensor macroscopically verifies the overall flatness of the end face and large-scale edge defects.

[0057] The defect identification and classification module 13 includes an image processing submodule and a defect classification submodule. The image processing submodule extracts image features from the ceramic coating image, the base film image, and the PVDF coating image, respectively. The defect classification submodule completes the base film end-face defect identification and classification based on the image features of the base film image and the target end-face contour data. The defect classification submodule completes the coating end-face defect identification and classification based on the image features of the ceramic coating image and the PVDF coating image.

[0058] After the image processing submodule extracts the image features of the ceramic coating image, base film image, and PVDF coating image, the defect classification submodule uses the extracted image features of the ceramic coating image, base film image, and PVDF coating image to perform defect identification and classification using a hierarchical identification strategy with the help of threshold segmentation, edge detection, or deep learning target detection algorithms: First level, the base film image obtained in transmitted light mode is used to microscopically identify defects such as wavy edges and interlayer slippage of a single-ring base film, while the three-dimensional point cloud data obtained by the laser contour sensor is used to macroscopically verify and identify defects such as uneven end faces and large-scale collapsed edges and warping; Second level, the ceramic coating image obtained in reflected light mode is used to microscopically identify the aforementioned defects of the ceramic coating; Third level, the PVDF coating image obtained in oblique light mode is used to microscopically identify the aforementioned defects of the PVDF coating.

[0059] Defects on the target end face are mainly classified into two categories: base film end face defects and coating layer end face defects. The specific classification, definition, judgment index, and measurement method of base film end face defects are shown in Table 1 below.

[0060] Table 1 Classification of defects on the end face of the base film ; The specific classifications, definitions, judgment criteria, and measurement methods of the coating layer end face are shown in Table 1 below.

[0061] Table 2 Classification of defects on the end face of the coating layer ; This embodiment only provides the judgment index for each specific defect in the two major categories of end face defects. As for the specific judgment threshold corresponding to each defect judgment index, it can be set by the operator according to the strictness of the diaphragm quality requirements and the production time requirements. This embodiment does not make specific limitations.

[0062] The end-face quality comprehensive evaluation module 14 is used to input the base film end-face defect identification and classification results and the coating end-face defect identification and classification results into a preset end-face quality comprehensive evaluation model to obtain a comprehensive score of the target end-face, and to complete the classification of the quality level of the target end-face based on the comprehensive score.

[0063] This embodiment preferably sets the end-face quality comprehensive evaluation model to include a dimensional scoring sub-model and a comprehensive scoring sub-model. The dimensional scoring sub-model is as follows:

[0064]

[0065] in, This indicates the quality score of the base film end face. This indicates the coating end face quality score. Indicates the first The index weight of each base film end face defect, Indicates the first The standardized score of each base film end-face defect under a pre-set quantitative scoring system. Indicates the first The index weight of each coating end face defect, Indicates the first The standardized score of each coating end face defect under a preset quantitative scoring system.

[0066] The preset quantitative scoring system for each of the above defects can be set by the operator according to the specific production requirements and process quality requirements of different diaphragm rolls. For example, the coating thickness requirements of PVDF coating are different in different diaphragm production processes, so the value limit of the preset quantitative scoring system for the relevant defects of PVDF coating will be different.

[0067] Taking the fluctuation amplitude in the end face wavy edge defect as an example, the preset quantitative scoring system can be shown in Table 3 below.

[0068] Table 3. Preset quantitative scoring system for undulation amplitude in wavy edge defect detection. ; As can be seen, the preset quantitative scoring system maps the values ​​of specific defect judgment indicators to a range of 0 to 100, that is, converts the detected defect judgment indicators into a percentage system. The higher the score, the better the performance of the defect judgment indicator, that is, the more minor the defect.

[0069] The weight of the end-face defect indicator represents the importance of a certain defect judgment indicator in its respective evaluation dimension. Its value ranges from 0 to 1, and the sum of the weights of all defect judgment indicators within the same dimension equals 1. ,at the same time .

[0070] The purpose of indicator weights is to address the varying degrees of impact different defects have on the quality of the diaphragm end face. A higher indicator weight indicates a greater impact of that defect on the final quality score. For example, in the power battery scenario, the weight of wavy edges is 0.25 (maximum), meaning that wavy edges have the greatest impact on end face quality; while the weight of contamination is only 0.05 (minimum), meaning that contamination has a relatively small impact on end face quality.

[0071] The weights of each evaluation indicator are determined comprehensively using mathematical methods such as the Analytic Hierarchy Process (AHP) or the entropy weight method. The specific steps are as follows: Constructing a judgment matrix: Invite industry experts to compare each evaluation indicator in pairs under the same dimension, and construct a judgment matrix according to the 1-9 scale (1 indicates equal importance, 9 indicates extreme importance).

[0072] Calculate the eigenvector: Normalize the judgment matrix and calculate the weight of each indicator.

[0073] Consistency test: Calculate the consistency ratio CR = CI / RI, where CI refers to the consistency index and RI refers to the random consistency index. When the consistency ratio CR < 0.1, the consistency of the judgment matrix is ​​considered acceptable.

[0074] Scenario adaptation adjustment: The weights of the indicators are fine-tuned according to the importance requirements of each indicator in different application scenarios (power batteries, consumer electronics, energy storage batteries) (see Table 4 below for details).

[0075] The comprehensive scoring sub-model is as follows: , in, This represents the overall score of the target end face. This indicates the dimensional weights for the base film end-face quality score. This indicates the dimensional weights for the coating end-face quality score.

[0076] Similarly, the specific values ​​of the dimension weights also need to be set according to the specific production requirements and process quality requirements of different diaphragm rolls. This embodiment provides a method for setting the specific values ​​of two dimension weights and the weights of each indicator under each dimension weight for different diaphragm production types, as shown in Table 4 below.

[0077] Table 4. Value settings for dimension weights and indicator weights in different diaphragm application scenarios. ; Based on the comprehensive score of the final target end face, the end face quality level can be classified as shown in Table 5 below.

[0078] Table 5 End Face Quality Grades ; The result output and feedback module 15 includes a display unit, a storage unit, and a feedback unit.

[0079] The display unit displays images, defect markers, comprehensive scores, and quality grades of the target end face in real time. Furthermore, it can display more detailed quality scores for the base film end face and the coating end face, based on the comprehensive score. The storage unit establishes a quality traceability file for the target end face. The feedback unit feeds the evaluation results of the target end face back to the coating / slitting process control system upstream of the diaphragm roll production, enabling automatic adjustment of coating or slitting parameters.

[0080] Of course, in other embodiments, the result output and feedback module may not be set up. Instead, after the production line manager receives the comprehensive score output by the end face quality comprehensive evaluation module 14, as well as the base film end face quality score and the coating end face quality score, the upstream coating and slitting process can be manually adjusted to achieve production linkage.

[0081] To further illustrate the technical solution of this invention, several test examples in specific scenarios are given below.

[0082] Example 1 (PVDF + ceramic composite coated diaphragm; qualified product) The sodium-ion battery coated separator end-face quality inspection and evaluation system of this invention is installed after the coating process in a sodium-ion battery separator production line. The separator is a polyolefin-based membrane + ceramic (Al2O3) coating layer + PVDF coating layer, with a width of 1000mm and a conveyor belt speed of 50m / min.

[0083] (1) End face image acquisition: Two 16K line array cameras acquire end face images in reflected light mode, oblique light mode and transmitted light mode respectively.

[0084] (2) End face contour scanning: The laser contour sensor scans radially along the end face to obtain the three-dimensional contour data of the end face.

[0085] (3) Ultraviolet fluorescence enhancement detection: The end face is irradiated with a 365nm ultraviolet LED light source, and a high-sensitivity camera is used with a fluorescence filter to collect fluorescence images and calculate the PVDF end face coverage.

[0086] (4) Layered defect identification: Base film layer: wavy edge fluctuation amplitude 0.2mm, collapse edge depth 0.03mm, end face flatness deviation 0.05mm; Ceramic coating: The ceramic coating on the end face is completely covered, with no peeling, no cracking, and no ceramic particles falling off; PVDF coating: 98.5% PVDF coverage on the end face, with no missed areas.

[0087] (5) Overall score: Base film end face quality score The coating end face quality score is 92 points. With a score of 98, the weighted configuration in the power battery scenario (α=0.40, β=0.60) results in a comprehensive score of Q=0.40×92+0.60×98=95.6, which is rated as Grade A (Excellent).

[0088] Example 2 (PVDF + ceramic composite coated diaphragm; non-conforming product) The data from another diaphragm roll is as follows: Base film layer: wavy edge fluctuation amplitude 0.6mm (65 points), collapse edge depth 0.12mm (70 points); Ceramic coating: Peel width of ceramic coating on end face is 0.5 mm (55 points), ceramic particle shedding density is 5 particles / cm³. 2 (60 points); PVDF coating: The PVDF coverage on the end face is only 82% (50 points).

[0089] Base film end face quality score The coating end face quality score is 68 points. The score is 55 points, and the overall score Q = 0.40 × 68 + 0.60 × 55 = 60.2 points, which is classified as Grade D (unqualified). The system triggers an alarm, the current diaphragm roll is automatically diverted, and a feedback signal is sent to the coating machine control system to automatically adjust the coating parameters.

[0090] Example 3 (PVDF end-face UV fluorescence enhancement detection) For diaphragm samples with extremely thin PVDF coatings (<2μm), conventional oblique illumination modes are insufficient to clearly identify the PVDF end-face boundaries. The ultraviolet (UV) light unit was activated: a 365nm UV LED light source illuminated the diaphragm end-face. PVDF produced a blue fluorescence response under UV excitation. A high-sensitivity camera, combined with a fluorescence filter, captured fluorescence images. PVDF-covered areas showed bright fluorescence, while uncovered areas were dark. Image processing algorithms calculated the PVDF coverage rate of the end-face. Testing showed that the current PVDF coverage rate of the diaphragm roll end-face was 97.2%, meeting the acceptable standard (≥95%).

[0091] The above test examples illustrate the usability, accuracy, and reproducibility of this system in various scenarios.

[0092] The embodiments of the present invention have the following key technical advantages: 1) Refined classification system for diaphragm roll end face defects: This invention provides a detailed classification of seven types of base film end face defects and five types of coating layer end face defects, and specifically defines the evaluation indicators and evaluation methods for each defect, especially the classification and quantification of coating layer-specific end face defects such as coating layer peeling, cracking, uneven thickness, ceramic particle detachment, and PVDF missing coating.

[0093] 2) Multi-mode light source layered imaging detection strategy: To address the differences in optical properties between ceramic coating (opaque) and PVDF coating (transparent), a layered imaging strategy using three modes—reflected light, transmitted light, and oblique light—is adopted to achieve independent detection and separate identification of the end faces of the base film, ceramic coating, and PVDF coating.

[0094] 3) PVDF transparent coating end face ultraviolet fluorescence enhancement detection technology: Utilizing the principle that 365nm ultraviolet light can excite PVDF to produce a fluorescence response, the transparent PVDF coating can be clearly identified and quantitatively evaluated at the end face, solving the technical problem of the difficulty in detecting the end face of PVDF transparent coating.

[0095] 4) Comprehensive evaluation model of base film and coating layer with weighted dimensional division: The end face quality is divided into base film quality dimension and coating layer quality dimension. The scores are calculated separately and then merged into a comprehensive quality score, and divided into four quality levels: A, B, C and D.

[0096] 5) Precise measurement method for coating end face thickness distribution: Utilizing the high-precision ranging function of a confocal displacement sensor, the coating end face thickness distribution is calculated using three-dimensional point cloud data of the end face contour, thereby achieving a quantitative evaluation of the coating end face thickness uniformity.

[0097] 6) Closed-loop feedback mechanism for test results and coating / slitting process: The end face quality evaluation results are fed back to the upstream coating process and slitting process control system in real time through the feedback module, so as to realize the automatic adjustment of process parameters.

[0098] 7) Dynamic configuration of evaluation model weights: The weight coefficients of the comprehensive evaluation model can be dynamically adjusted according to different application scenarios of sodium-ion battery separators (power batteries, consumer electronics, energy storage, etc.).

[0099] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A quality inspection and evaluation system for the end face of a sodium-ion battery coated separator, characterized in that, include: The end face image acquisition module includes a camera submodule and a light source submodule. The camera submodule is set on one side of the target end face of the diaphragm roll to be detected. The light source submodule and the camera submodule cooperate to form a reflected light mode, a transmitted light mode and an oblique light mode, and the camera submodule acquires ceramic coating image, base film image and PVDF coating image respectively. The end face contour scanning module includes a radial scanning submodule, which scans along the radial direction of the target end face to acquire the target end face contour data; The defect identification and classification module includes an image processing submodule and a defect classification submodule. The image processing submodule extracts image features from the ceramic coating image, the base film image, and the PVDF coating image, respectively. The defect classification submodule completes the base film end-face defect identification and classification based on the image features of the base film image and the target end-face contour data. The defect classification submodule completes the coating end-face defect identification and classification based on the image features of the ceramic coating image and the PVDF coating image. The end-face quality comprehensive evaluation module is used to input the defect identification and classification results of the base film end face and the defect identification and classification results of the coating end face into a preset end-face quality comprehensive evaluation model to obtain a comprehensive score of the target end face, and to complete the classification of the quality level of the target end face based on the comprehensive score.

2. The sodium-ion battery coated separator end-face quality inspection and evaluation system according to claim 1, characterized in that, The light source submodule works in conjunction with the camera submodule to implement reflected light mode, transmitted light mode, and oblique light mode, including: In the reflected light mode, both the camera submodule and the light source submodule are located on one side of the target end face. The light emitted by the light source submodule illuminates the target end face at a first preset angle, and the camera submodule receives the light reflected from the target end face to obtain the ceramic coating image. In the transmitted light mode, the camera submodule is located on one side of the target end face, and the light source submodule is located on the opposite side of the target end face. The light emitted by the light source submodule penetrates the target end face along the axial direction of the diaphragm roll and is received by the camera submodule to obtain the base film image. In the oblique illumination mode, both the camera submodule and the light source submodule are located on one side of the target end face. The light emitted by the light source submodule illuminates the target end face at a second preset angle, and the camera submodule receives the light reflected from the target end face to obtain the PVDF coating image. The first preset angle is greater than the second preset angle.

3. The sodium-ion battery coated separator end-face quality inspection and evaluation system according to claim 2, characterized in that, The light source submodule also includes an ultraviolet light unit and a fluorescent filter. In the oblique light mode, the light source submodule emits ultraviolet light through the ultraviolet light unit and illuminates the target end face at the second preset angle. The camera submodule receives the ultraviolet light reflected from the target end face through the fluorescent filter to obtain the PVDF coating image.

4. The sodium-ion battery coated separator end-face quality inspection and evaluation system according to claim 3, characterized in that, The wavelength of the ultraviolet light is 365nm.

5. The sodium-ion battery coated separator end-face quality inspection and evaluation system according to any one of claims 1 to 4, characterized in that, The end face image acquisition module is set after the winding station of the diaphragm slitting machine or at an independent detection station, and the camera sub-module includes a line scan camera or an area scan camera.

6. The sodium-ion battery coated separator end-face quality inspection and evaluation system according to any one of claims 1 to 4, characterized in that, The image acquisition resolution of the end face image acquisition module is not less than 5μm / pixel, and the image acquisition frequency of the end face image acquisition module is linked to the conveyor speed of the diaphragm roll.

7. The sodium-ion battery coated separator end-face quality inspection and evaluation system according to claim 1, characterized in that, The end face contour scanning module further includes an axial movement submodule, which drives the radial scanning submodule to move along the axial direction of the diaphragm roll.

8. The sodium-ion battery coated separator end-face quality inspection and evaluation system according to claim 1, characterized in that, The radial scanning submodule is a laser contour sensor or a confocal displacement sensor. The scanning accuracy of the radial scanning submodule is not less than 0.01 mm, and the sampling interval is not greater than 0.1 mm.

9. The sodium-ion battery coated separator end face quality detection and evaluation system according to claim 1, characterized in that, The comprehensive evaluation model for end-face quality includes a dimensional scoring sub-model and a comprehensive scoring sub-model. The dimensional scoring sub-model is as follows: ， ， in, This indicates the quality score of the base film end face. This indicates the coating end face quality score. Indicates the first The index weight of each base film end face defect, Indicates the first The standardized score of each base film end-face defect under a pre-set quantitative scoring system. Indicates the first The index weight of each coating end face defect, Indicates the first The standardized score of each coating end face defect under a preset quantitative scoring system; The comprehensive scoring sub-model is as follows: ， in, This represents the overall score of the target end face. This indicates the dimensional weights for the base film end-face quality score. The dimensional weights represent the quality scores of the coating end face.

10. The sodium-ion battery coated separator end-face quality detection and evaluation system according to claim 1, characterized in that, It also includes a result output and feedback module, which includes a display unit, a storage unit, and a feedback unit; The display unit is used to display the image of the target end face, defect markings, the comprehensive score, and the quality level in real time. The storage unit is used to establish a quality traceability file for the target end face; The feedback unit is used to feed back the evaluation results of the target end face to the coating / slitting process control system upstream of the diaphragm roll production, and automatically adjust the coating parameters or slitting parameters.

Images