Method for rapidly detecting OverHang of positive electrode and negative electrode of laminated battery

Abstract

The invention discloses a method for rapidly detecting OverHang of a positive electrode and a negative electrode of a laminated battery, and relates to the technical field of laminated battery detection.The method comprises the steps that a micro-focus X-ray tube is properly modified, and an electron beam deflection system is installed; the electron beam deflection system realizes electron beam deflection scanning by controlling the current of a deflection magnetic field coil by a remote computer through a communication serial port; the laminated battery is positioned in a reference coordinate system of the detection platform through the clamping tool, it is ensured that the angular position of the battery and the relative position of the X-ray source are kept consistent during detection each time, the X-ray source and the detector are relatively fixed, and multi-angle projection is achieved through electron beam deflection. According to the method for rapidly detecting the OverHang of the positive electrode and the negative electrode of the laminated battery and the method for controlling the deflection of the electron beam to generate the multi-view projection X-ray by the change of the electromagnetic field, a multi-view two-dimensional picture of the laminated battery is obtained, the OverHang data of the laminated battery can be conveniently and rapidly obtained without a complex CT (Computed Tomography) method, and the method has high application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection of laminated batteries, and particularly to a method for rapidly detecting OverHang of positive and negative electrodes of laminated batteries. BACKGROUND

[0002] In recent years, consumers have increasingly high requirements for the use of electronic products, and accordingly, fast charging technology for various electronic products has begun to enter the market, which has posed greater challenges to the technical development of lithium batteries. Compared with wound structure batteries, laminated batteries are highly valued for their high space utilization, small internal resistance, and good rate performance.

[0003] In order to ensure the safety of the battery, there is a requirement for OverHang when designing and producing the battery, and the existing technology is detected by an X-ray device. However, the X-ray device is expensive, and the detection time is long, which leads to low production efficiency. at Laminated batteries are obtained by layer-by-layer interlacing of single positive and negative electrodes, and the electrode sheets are discontinuous and prone to loosen and misalign during stacking and shifting, which puts higher requirements on the alignment of the electrode group. Only the planar image of the X-ray device can obtain the OverHang of the entire battery, and cannot guarantee the stacking stability between the electrode sheets, which may lead to safety hazards.

[0004] Previously, someone proposed placing the battery close to the detector and only using a small part of the rays to obtain the projection of the adjacent electrodes of the laminated battery with a small magnification ratio. Due to the small magnification ratio, the projection only occupies a few pixels of the flat panel detector, so the OverHang data fluctuates greatly in repeated measurements, the detection repeatability is poor, the probability of missed detection and false detection is high, and in addition, some CT detection methods require a mechanical module to drive the battery to obtain images at multiple angles, which is expensive and time-consuming, and has low detection efficiency, resulting in insufficient production capacity of the production line.

[0005] Therefore, we propose a method for rapidly detecting OverHang of positive and negative electrodes of laminated batteries to solve the problems raised in the above background. SUMMARY

[0006] The present application aims to provide a method for rapidly detecting OverHang of positive and negative electrodes of laminated batteries to solve the problem that the existing laminated battery detection process cannot improve the detection efficiency while ensuring the detection effect, resulting in insufficient production capacity of the production line and failing to meet the production demand.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solution: a method for rapidly detecting OverHang of positive and negative electrodes of laminated batteries, comprising: The microfocus X-ray tube is appropriately modified and an electron beam deflection system is installed. The electron beam deflection system is controlled by a remote computer via a communication serial port to deflect and scan the electron beam. The stacked batteries are positioned in the reference coordinate system of the inspection platform by clamping fixtures to ensure that the relative position of the battery corner position and the X-ray source remains consistent during each inspection. The X-ray source and the detector are relatively fixed, and multi-angle projection is achieved by deflecting the electron beam. The electron gun emits an electron beam, which is focused by the focusing system. The electron beam deflection system precisely adjusts the changes in the electromagnetic field to control the deflection direction of the electron beam, so that it hits the target surface at different time periods, thereby generating multi-view projection data. Multiple two-dimensional projection images are obtained, and the boundaries of each layer are automatically identified and the OverHang value is calculated through an algorithm. The stacking alignment quality is determined in combination with the preset tolerance zone. After image stitching and coordinate alignment, multi-view projection data can also generate a complete three-dimensional projection atlas, which can be used to accurately analyze the relative displacement of each electrode and diaphragm. During the detection process, the system monitors the stability of electron beam deflection and X-ray intensity fluctuations in real time, dynamically adjusts the gain parameters to ensure image consistency, and records the timestamp of each deflection angle and the corresponding projected image to ensure time synchronization of multi-view data.

[0008] By adopting the above technical solution, a method of generating multi-view projection X-rays by controlling the deflection of the electron beam through electromagnetic field changes can be used to obtain two-dimensional images of stacked batteries from multiple perspectives. This method can conveniently and quickly obtain the overHang data of the stacked batteries without going through complex CT methods, and has high application value.

[0009] Preferably, the positioning mechanism precisely adjusts the spatial orientation of the stacked batteries to avoid positional deviations caused by inconsistent battery processing and the clamping fixture transporting the batteries to the testing platform.

[0010] Preferably, due to the increased detection cycle time, increased battery thickness, and deviation in repeatability accuracy, the positional drift of the battery in the detection field of view under high magnification conditions will affect the OverHang measurement accuracy. Fast electron beam deflection can dynamically correct the deflection path in sub-millisecond time, compensate for positional drift in real time on the image, and ensure clear imaging of the stacked battery by multi-view projection.

[0011] Preferably, the items requiring dynamic adjustment include, but are not limited to, astigmatism caused by the image plane of the focusing lens not coinciding with the target surface, and inherent deflection astigmatism of the focusing system. Preferably, the electron beam deflection system and the X-ray target are integrated within the vacuum cavity.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: The method for rapidly detecting the overhang of the positive and negative electrodes of stacked batteries uses electromagnetic field changes to control the deflection of the electron beam to generate multi-view projection X-rays, thereby obtaining multi-view two-dimensional images of the stacked batteries. It can easily and efficiently obtain the overhang data of stacked batteries without relying on complex CT structures and reconstruction processes. When using multi-view projection, the battery imaging can be relatively close to the X-ray source, which can achieve a high magnification effect, thereby enabling accurate measurement on the detector and making the repeatability of the overhang data perform better. 1. It can obtain alignment images under high magnification, thereby effectively improving the spatial resolution and geometric accuracy of imaging. Especially under the conditions of large field of view and high magnification, it can still maintain good image consistency and alignment accuracy, providing a high-quality projection data foundation for the repeatability index of OverHang data of subsequent stacked cells. 2. By precisely controlling the electromagnetic field to achieve high-speed deflection of the electron beam, the multi-view projection acquisition time is significantly shortened, the detection efficiency is improved, and the online detection needs of the production line are met. Compared with the long time consumption and complex structure of traditional mechanical rotating CT, this method does not require moving the battery or mechanical parts of the equipment. The system has high stability and low maintenance cost, and can achieve rapid batch detection. It effectively solves the problem of limited production capacity caused by the detection speed bottleneck of stacked batteries, and further enhances its practical value in industrial applications. 3. The electron beam deflection system and the X-ray target are integrated into the vacuum cavity, with a compact overall structure. This avoids vibration interference caused by external mechanical movement, ensuring high stability of the focal position and image clarity. At the same time, the system can precisely control the deflection current through a remote computer, enabling flexible programming of the electron beam scanning path to adapt to different battery sizes and detection requirements, and has good versatility and scalability. 4. Samples can be placed relatively close to the radiation source. Combined with a high dynamic range flat panel detector, high signal-to-noise ratio projection images can be acquired under low-dose conditions, further improving the safety and economy of the test, while reducing the impact of radiation on operators and meeting the safety standards of industrial non-destructive testing. 5. Achieves a larger magnification ratio, significantly improves spatial resolution, greatly increases the detection rate of minute defects, improves detection repeatability and effectively reduces the probability of missed and false detections, and is especially suitable for the accurate identification of micron-level defects inside stacked batteries. Attached Figure Description

[0013] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Fig. 1 This is a schematic diagram of the stacked battery of the present invention in a static state; Fig. 2 This is a schematic diagram of a conventional two-dimensional imaging system. Fig. 3 This is a schematic diagram of the battery and the radiation source. Fig. 4 This is a two-dimensional imaging schematic diagram of the stacked battery electrode sheets of the present invention; Fig. 5 This is a schematic diagram of the structure where the stacked battery of the present invention has a positional deviation. Detailed Implementation

[0014] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0015] Please see Figs. 1-5A method for rapidly detecting overhang at the positive and negative electrodes of stacked solar cells involves modifying a micro-focus X-ray tube and installing an electron beam deflection system. This system, controlled remotely by a computer via a serial communication port, deflects the electron beam by controlling the current in the deflection magnetic field coil. The stacked solar cells are positioned in the reference coordinate system of the detection platform using clamping fixtures, ensuring that the relative position of the cell corners to the X-ray source remains consistent during each detection. The X-ray source and detector are relatively fixed. Multi-angle projection is achieved through electron beam deflection. The electron gun emits an electron beam, which is focused by the focusing system. The electron beam deflection system precisely adjusts the electromagnetic field changes to control the deflection direction of the electron beam, causing it to impact the target surface at different times, thereby generating multi-view projection data and obtaining multiple two-dimensional projection images. An algorithm automatically identifies the boundaries of each layer and calculates the overhang value. Combined with a preset tolerance zone, the stack alignment quality is determined. After image stitching and coordinate alignment, the multi-view projection data can also generate a complete three-dimensional projection atlas for precision analysis. The system accurately analyzes the relative displacement of each electrode and diaphragm. During the detection process, the system monitors the stability of electron beam deflection and X-ray intensity fluctuations in real time, dynamically adjusts the gain parameters to ensure image consistency, and records the timestamp of each deflection angle and the corresponding projected image to ensure synchronization of multi-view data. The positioning mechanism precisely adjusts the spatial orientation of the stacked battery to avoid positional deviations caused by battery processing inconsistencies and the clamping fixture transporting the battery to the detection platform. Due to the increased detection cycle, increased battery thickness, and deviations in repeatability accuracy, the positional drift of the battery in the detection field of view under high magnification conditions will affect the OverHang measurement accuracy. The rapid electron beam deflection can dynamically correct the deflection path in sub-millisecond time and compensate for positional drift in real time on the image to ensure clear imaging of the stacked battery in multi-view projection. The dynamic adjustments required include, but are not limited to, astigmatism caused by the non-coincidence of the image plane of the focusing lens and the target surface, and the inherent deflection astigmatism of the focusing system. The electron beam deflection system and the X-ray target are integrated in a vacuum cavity. The deflection D of the electron beam on the target plane is theoretically linearly related to the deflection coil current I (referred to as deflection linearity). However, factors such as the winding precision and installation position of the deflection coil can affect the deflection linearity of the electron beam. To test the performance parameters of the electron beam scanning system, such as deflection linearity, focal point repeatability, and spatial resolution, a microfocus X-ray tube was appropriately modified, and an electron beam deflection system was installed. The electron beam deflection system achieves electron beam deflection scanning by remotely controlling the current of the deflection magnetic field coil via a communication serial port.

[0016] Fig. 1 In the process, the stacked cells remain stationary. The electron beam deflection system controls the electron beam to deflect and scan different positions on the target surface according to a certain time sequence to generate X-rays. The flat panel detector synchronously acquires DR images projected under different X-ray focal points.

[0017] Fig. 2 This conventional two-dimensional imaging method places the battery close to the detector and uses only a small portion of the rays to obtain the projection of adjacent electrodes of the stacked battery at a low magnification. Due to the low magnification, the projection occupies only a few pixels of the flat panel detector, resulting in large fluctuations in the OverHang data from repeated measurements, poor detection repeatability, and a high probability of missed and false detections. Fig. 3 To place the battery close to the X-ray source, a high magnification projection of adjacent electrodes of the stacked battery can be obtained. Although the projection only occupies a few pixels of the flat panel detector, which is convenient for size measurement, only the electrode facing the X-ray source can be separated. Due to the optical path of the perspective imaging, the projections of the electrodes on both sides will overlap, making it impossible to distinguish the positive and negative electrode boundaries and obtain OverHang data. Fig. 4 The image shows three DR images of stacked battery electrodes generated by projection under three X-ray focal points. The position of the electrode images changes left and right with the change of deflection current. It can be seen that the electrodes can be separated to obtain clear projections. Fig. 5 If the stacked battery is tilted or deviated due to mechanical positioning, the electrode facing the X-ray source may overlap due to the light path of the perspective imaging. However, by moving the electron beam spot point by point, X-ray focal points at different positions can still be generated, and continuous and distinguishable DR image projections of the stacked battery electrode can still be found. Experimental results on the deflection linearity and focal position repeatability of the electron beam deflection system show that the deflection linearity and focal position repeatability of the electron beam deflection system are very good, the DR images of the corresponding electrodes are clear, and the effects of deflection defocus and distortion are negligible, which meets the imaging requirements of the stacked battery overHang data. All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art, and the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here.

[0018] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for rapidly detecting overhang at the positive and negative electrodes of a stacked battery, characterized in that, include: The microfocus X-ray tube is appropriately modified and an electron beam deflection system is installed. The electron beam deflection system is controlled by a remote computer via a communication serial port to deflect and scan the electron beam. The stacked batteries are positioned in the reference coordinate system of the inspection platform by clamping fixtures to ensure that the relative position of the battery corner position and the X-ray source remains consistent during each inspection. The X-ray source and the detector are relatively fixed, and multi-angle projection is achieved by deflecting the electron beam. The electron gun emits an electron beam, which is focused by the focusing system. The electron beam deflection system precisely adjusts the changes in the electromagnetic field to control the deflection direction of the electron beam, so that it hits the target surface at different time periods, thereby generating multi-view projection X-ray data. Multiple two-dimensional projection images are obtained, and the boundaries of each layer are automatically identified and the OverHang value is calculated through an algorithm. The stacking alignment quality is determined in combination with the preset tolerance zone. After image stitching and coordinate alignment, multi-view projection data can also generate a complete three-dimensional projection atlas, which can be used to accurately analyze the relative displacement of each electrode and diaphragm. During the detection process, the system monitors the stability of electron beam deflection and X-ray intensity fluctuations in real time, dynamically adjusts the gain parameters to ensure image consistency, and records the timestamp of each deflection angle and the corresponding projected image to ensure time synchronization of multi-view data.

2. The method for rapid detection of overhang at the positive and negative electrodes of a stacked battery according to claim 1, characterized in that: The positioning mechanism precisely adjusts the spatial orientation of the stacked batteries to avoid positional deviations caused by inconsistent battery processing and the clamping fixtures transporting the batteries to the testing platform.

3. The method for rapid detection of overhang at the positive and negative electrodes of a stacked battery according to claim 1, characterized in that: Due to the increased detection cycle time, increased battery thickness, and deviations in repeatability accuracy, the positional drift of the battery in the detection field of view under high magnification conditions will affect the OverHang measurement accuracy. Fast electron beam deflection can dynamically correct the deflection path in sub-millisecond time, compensate for positional drift in real time on the image, and ensure clear imaging of the stacked battery by multi-view projection.

4. The method for rapidly detecting overhang of the positive and negative electrodes of a stacked battery according to claim 1, characterized in that: The items that need to be dynamically adjusted include, but are not limited to, astigmatism caused by the image plane of the focusing lens not coinciding with the target surface, and inherent deflection astigmatism of the focusing system.

5. The method for rapidly detecting overhang at the positive and negative electrodes of a stacked battery according to claim 1, characterized in that: The electron beam deflection system is integrated with the X-ray target within a vacuum cavity.

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