Optical imaging-based lithium-ion battery volume detection device and applications thereof

Abstract

The application provides a kind of optical imaging method detection battery volume device, which comprises optical imaging module, battery rotation module, battery charge-discharge module and photoelectric synchronization module, DC power supply powers stepper motor, function generator outputs synchronous waveform to stepper motor controller and electronic coupling element respectively, so that electronic coupling element collects a frame of image every time stepper motor rotates a fixed angle, and the cycle goes on; real-time monitoring module, which includes a monitor and a computer host, the computer host is used for real-time acquisition of the projection image of lithium ion battery delivered by the electronic coupling element, and the image is processed by edge positioning and volume reconstruction method to obtain the volume of the lithium ion battery to be measured in real time, and the volume evolution curve and electrical change curve of the lithium ion battery during the charge-discharge process are output in real time on the monitor.

Description

Technical Field

[0001] This invention relates to methods for detecting the volume of lithium-ion batteries and their application in predicting battery electrical performance. Specifically, it relates to optical imaging, mechanical rotation, edge localization, and volume reconstruction of batteries, as well as establishing the correlation between battery volume and electrical performance parameters. Background Technology

[0002] The application of lithium-ion batteries has brought immense convenience to people's lives. The 2019 Nobel Prize in Chemistry was awarded for the development of lithium-ion batteries, which "lay the foundation for a wireless, fossil fuel-free society and greatly advance human progress." It is no exaggeration to say that lithium-ion battery technology is a great invention that has propelled human society forward. However, lithium-ion battery technology is not perfect. The biggest bottleneck restricting its application is the degradation of battery life and safety issues. This is because, with charge-discharge cycles, irreversible side reactions occur inside lithium-ion batteries, ultimately causing battery capacity decay, accompanied by volume expansion, fire, and even explosion.

[0003] To address this challenge, researchers aim to monitor the operating status of lithium-ion batteries through volume changes, thereby predicting battery life and safety. Traditional battery volume detection methods primarily rely on various mechanical methods, using micrometers or pressure sensors to detect localized volume deformations. However, these methods have several drawbacks: (1) they lack spatial resolution, detecting only localized deformations rather than the actual volume; (2) they have low throughput, making simultaneous detection of multiple batteries impossible; and (3) they lack versatility, being suitable only for soft-pack batteries and not applicable to more common hard-shell batteries such as the 18650 battery.

[0004] To address the shortcomings of traditional detection methods, Wang Wei and Jiang Wenxuan of Nanjing University proposed "A Real-Time Detection Method and Device for Battery Expansion Based on Optical Imaging" (application number CN 202111639683.1). This invention introduces optical methods into the measurement of volume expansion, utilizing the projection of the battery's cross-section for edge localization, thereby obtaining real-time information on the diameter evolution of the battery during charging and discharging. This method features simple device, high detection throughput, high spatial resolution, and non-destructive testing. However, this method only detects the diameter change of the battery at a certain angle. For lithium-ion batteries, volume expansion is not uniform; the degree of expansion varies greatly at different angles, making it impossible to deduce the true volume of the lithium-ion battery from the diameter at a single angle. Therefore, obtaining the true volume evolution of lithium-ion batteries during charging and discharging in real time remains a significant challenge. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide an optical imaging method for detecting battery volume, the device comprising:

[0006] A lithium-ion battery volume detection device based on optical imaging, characterized in that the device comprises:

[0007] The optical imaging module uses light-emitting diodes as a light source and employs projection imaging to perform real-time optical imaging of the battery diameter on the electronic coupling element.

[0008] The battery rotation module is used to drive the battery to rotate continuously at a preset speed in order to measure the battery diameter at different angles, thereby reconstructing the accurate volume of the battery.

[0009] A battery charge / discharge module is used to perform charge / discharge cycles on lithium-ion batteries and monitor their electrical parameters.

[0010] The optoelectronic synchronization module includes a function generator, a DC power supply, and a stepper motor controller. The DC power supply powers the stepper motor, and the function generator outputs a synchronous waveform to the stepper motor controller and the electronic coupling element, so that the electronic coupling element acquires one frame of image every time the stepper motor rotates a fixed angle, and so on. The real-time monitoring module includes a monitor and a computer host. The computer host is used to acquire the projected image of the lithium-ion battery delivered by the electronic coupling element in real time, and processes the image through edge localization and volume reconstruction methods to obtain the volume of the lithium-ion battery under test in real time. The volume evolution curve and electrical change curve of the lithium-ion battery during the charging and discharging process are output to the monitor in real time.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] This patent represents an iterative upgrade of the previous generation method (application number CN 202111639683.1), transitioning from detecting the evolution of the battery's diameter to detecting its volume evolution. This enables online detection of battery volume during charging and discharging, a task that traditional battery expansion detection methods cannot accomplish. Furthermore, this patent features non-destructive testing, high throughput, and broad applicability. After obtaining the battery's volume information, it establishes a correlation with the battery state, i.e., SOC or SOH, to perform real-time and accurate assessment of the battery's condition. Ultimately, this enables monitoring of battery aging, rapid capacity reduction, and hazard warnings, addressing industry pain points and promoting the safe and reliable development of the battery industry. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the device for detecting battery volume using the optical imaging method of the present invention;

[0014] Figure 2 Schematic diagram of a battery optical projection imaging device;

[0015] Figure 3 A schematic diagram of the battery edge localization and volume reconstruction algorithm;

[0016] Figure 4-6 This is a three-dimensional view of the brush-based battery rotating clamp of the present invention;

[0017] Figure 7-8 A perspective view of another miniaturized battery rotating clamp structure provided by the present invention;

[0018] Figure 9 The battery volume evolution curve and voltage curve provided in the embodiments of the present invention;

[0019] Figure 10 The morphological changes of the battery during charge-discharge testing provided in the embodiments of the present invention;

[0020] Figure 11 The correlation between battery volume and SOH is provided for embodiments of the present invention.

[0021] Among them, 1-Light Emitting Diode Light Source; 2-Columnar Lithium-ion Battery; 3-Charge Coupled Element Camera; 4-Battery Rotation Module; 411-Upper Top Plate; 412-Side Support Post; 413-Brush Holder; 414-Upper Gasket for Positive Battery Terminal; 415-Positive Copper Gasket; 416-Lower Gasket for Positive Battery; 417-Upper Gasket for Negative Battery; 418-Copper Gasket for Negative Battery; 419-Lower Gasket for Negative Battery; 421-Battery Conductive Clamp; 422-Battery Motor Coupling; 431-Wire; 432-Stepper Motor; 5-Constant Temperature Chamber; 6-Monitor; 7-Computer Host; 8-Battery Testing System; 9-Function Generator; 10-DC Power Supply. Detailed Implementation

[0022] Example 1: Battery Rotating Clamp

[0023] like Figures 4-6 As shown, this embodiment provides a battery rotating clamp, which includes a stepper motor, a lower conductive ring fixedly connected to the motor shaft of the stepper motor, an upper conductive ring axially corresponding to the lower conductive ring, at least one upper brush holder electrically connected to the upper conductive ring, and at least one lower brush holder electrically connected to the lower conductive ring. The upper and lower ends of the battery are respectively inserted into the upper and lower conductive rings. The stepper motor drives the lithium-ion battery to rotate circumferentially with the upper and lower conductive rings through the lower conductive ring.

[0024] The upper and lower brush holders are respectively connected to wires. Due to their own conductivity, the electricity on the wires can be directly conducted through the upper and lower brush holders to the upper and lower conductive rings. This allows the upper and lower brush holders and their wires to be electrically connected without rotating when the upper and lower conductive rings rotate. This avoids the technical problem of wires getting tangled due to circumferential rotation.

[0025] like Figure 4 As shown, the stepper motor is equipped with multiple vertically extending side rods 412, and the top of the multiple side rods is connected to a top plate 411. The space formed by the multiple side rods and the top plate 411 is used to accommodate the upper conductive coil, the lower conductive coil, and the lithium-ion battery. The upper brush holder and the lower brush holder pass through the upper and lower sides of the multiple side rods 412 respectively to be electrically connected to the upper conductive coil and the lower conductive coil.

[0026] A schematic diagram of the battery rotation module structure based on brushes is shown below. Figure 4 , Figure 5 and Figure 6 As shown, the components of this module need to be assembled from bottom to top according to the diagram. First, assemble the upper negative washer 417, the copper negative washer 418, and the lower negative washer 419 using long screws to form a lower conductive ring. Then, fix the motor shaft of the stepper motor 432 to the lower negative washer 419 with screws. At this time, insert the lithium-ion battery 2 with the negative terminal facing down into the upper negative washer 417 and further fix it with screws. Assemble the upper positive washer 414, the copper positive washer 415, and the lower positive washer 416 using long screws to form an upper conductive ring. Then, insert the battery 2 with the positive terminal facing up into the lower positive washer 416. Further secure with screws; after inserting conductive carbon brushes into the brush holders, insert the eight brush holders 413 into the four side uprights 412 respectively, and secure them with screws; the four upper carbon brush heads need to be in close contact with the positive electrode copper washer 415, and the four lower carbon brush heads need to be in close contact with the negative electrode copper washer 418. All carbon brush tails are led out with wires 431 and connected to the blue battery testing system 8; finally, connect the upper top plate to the positive electrode upper washer 414 through the bearing, and secure 411 to the four side uprights 412 with screws to complete the installation.

[0027] The working principle of Scheme 1 is to drive the rotation of the lithium-ion battery through the motor shaft to obtain battery projections at different angles; at the same time, the connection between the battery, copper gasket, carbon brush, wire, and battery testing system ensures that the rotation and charge / discharge cycle of the lithium-ion battery can be carried out simultaneously.

[0028] Example 2: Miniaturized Battery Rotary Clamp

[0029] like Figure 7 and Figure 8As shown, this embodiment provides a miniaturized battery rotating clamp, which includes a stepper motor 432, a coupling 422 connected to the motor shaft of the stepper motor, and a conductive clamp 421. The conductive clamp 421 is axially aligned with the coupling 422. The upper and lower ends of the lithium-ion battery are respectively inserted into the conductive clamp and the coupling. The stepper motor drives the coupling and the conductive clamp to rotate circumferentially together.

[0030] The conductive clamp 421 has a conductive top and a conductive sidewall. The conductive top and the conductive sidewall are respectively provided with a top conductive hole and a side conductive hole. Based on the characteristics of lithium-ion batteries, the top is the positive electrode and the entire side and bottom are the negative electrodes. Therefore, charging and discharging can be achieved by connecting wires through the top conductive hole and the side conductive hole.

[0031] Assemble the components of this module from bottom to top as shown in the diagram. First, fix the motor shaft of the stepper motor 432 to the battery motor coupling 422 with screws. Then, insert the lithium-ion battery with the positive terminal facing up into the battery motor coupling 422 and fix it with screws. Finally, put the conductive clamp 421 over the positive terminal of the battery 2 and fix it with three copper screws. Connect the tail end of the copper screw to the wire 431 and connect it to the blue battery test system 8. The installation is complete.

[0032] The working principle of Scheme 2 is as follows: the rotation of the lithium-ion battery is driven by the motor shaft to obtain battery projections at different angles; at the same time, the connection between the battery, copper screw, wire and battery testing system ensures that the rotation and charge-discharge cycle of the lithium-ion battery can be carried out simultaneously.

[0033] In this embodiment, the wire needs to be of sufficient length to accommodate the circumferential rotation of the lithium-ion battery.

[0034] Example 3: Battery volume calculation module and the correlation between battery volume and electrical performance

[0035] like Figure 1 As shown, this embodiment provides a lithium-ion battery volume detection device, including: an optical imaging module, a battery rotation module, a battery charging and discharging module, a photoelectric synchronization module, and a real-time monitoring module. The optical imaging module includes a light-emitting diode (LED light source) 1 and an electronic coupling element (CCD camera) 3, such as... Figure 2 As shown, a light-emitting diode (LED) 1 is placed in front of the battery 2 to be tested, and an electronically coupled element (CCD) 3 is placed behind the battery 2 to collect the projected image of the battery.

[0036] The battery rotation module uses the clamp described in Embodiment 1 or Embodiment 2 to drive the battery 2 under test to rotate circumferentially;

[0037] The battery charging and discharging module is the Wuhan Lanhe Battery Testing System 8, model CT3001C. Figure 1 As shown, the lithium-ion battery 2 under test is charged and discharged through a wire connected to the battery rotation module 4. Its function is to monitor various electrical parameters of the lithium-ion battery 2, including but not limited to voltage, current, charge, SOC and SOH.

[0038] The photoelectric synchronization module includes a function generator 9, a DC power supply 10, and a stepper motor controller. Its function is to synchronize the CCD camera 3 in the optical module and the stepper motor 432 in the battery rotation module 4. Specifically, the DC power supply 10 supplies power to the stepper motor 432, and the function generator 9 outputs a synchronization waveform to the stepper motor 432 and the CCD camera 3 respectively, so that every time the stepper motor 432 rotates by a fixed angle, the CCD camera 3 acquires a frame of image, and so on until the test ends.

[0039] The real-time monitoring module includes a monitor 6 and a computer host 7. This module mainly runs image acquisition software and real-time data processing code. The real-time monitoring module is used to acquire projected images of the battery in real time, and process the images through edge positioning and volume reconstruction methods to obtain the volume of the lithium-ion battery 2 under test in real time, and output the volume evolution curve of the lithium-ion battery 2 under test during the charging and discharging process on the monitor 6 in real time.

[0040] According to the lithium-ion battery testing device provided in this embodiment, this embodiment further provides a method for predicting the electrical performance of lithium-ion batteries, the method comprising the following steps:

[0041] Step 1) as Figure 1 As shown, the entire test was conducted in constant temperature chamber 5 to ensure a constant ambient temperature; first, the LED light source 1 was turned on and preheated for about two hours to make the light source 1 work in a stable state.

[0042] Then turn on the camera 3 and set a suitable exposure time; then turn on the monitor 6, computer host 7, battery test system 8, function generator 9 and DC power supply 10 in sequence.

[0043] Step 2) Use function generator 9 to input the same waveform to camera 3 and stepper motor 432, so that camera 3 starts to acquire images and lithium-ion battery 2 starts to rotate at a fixed speed, in order to obtain the diameter of the battery at different angles; at the same time, battery testing system 8 performs charge and discharge tests on lithium-ion battery.

[0044] Step 3) Obtain high-precision edge position information of lithium-ion battery 2 through the projection image of lithium-ion battery 2, and obtain the diameter information of lithium-ion battery 2 through edge positioning method; then obtain the diameter information of battery at different angles by rotating the battery rotating fixture, and obtain the volume of battery through volume reconstruction algorithm;

[0045] Edge localization methods include: In grayscale images recorded by a CCD camera, black and white can be quantized using grayscale values, i.e., the darker the image, the smaller the grayscale value, and the lighter the image, the larger the grayscale value; Figure 3 For example, a battery is projected into a grayscale image, where the battery portion is black due to light blocking, and the light source portion is white. In the optical image of the battery, the boundary between black and white is the battery edge. However, if the grayscale value is used directly as the basis for positioning, although the algorithm is simple, the accuracy is insufficient, only achieving pixel-level positioning accuracy. Since the positional movement of the battery edge due to expansion and contraction is much smaller than one pixel, an edge fitting algorithm is needed to obtain the sub-pixel level battery edge position.

[0046] For example, the specific implementation steps of the edge fitting algorithm are as follows:

[0047] 1) For any angle θ i In the projected image of lithium-ion battery 2 captured by the CCD camera, the height of lithium-ion battery 2 occupies approximately 700 pixels, and its diameter occupies approximately 200 pixels. The left edge X of the lithium-ion battery 2 image... L For example, at any height H of the battery section i Take an image with a height of 1 pixel and a length of 80 pixels, centered at the edge. The selected image is characterized by a grayscale value that changes from white (light source area) to black (battery area) from left to right, that is, a set of numbers where the grayscale value decreases from large to small. We call this the "original curve".

[0048] 2) Differentiate the original curve to obtain the first-order differential curve, then apply Gaussian fitting to the first-order differential curve to obtain the coordinates X of the left edge position. L The fitting formula is as follows:

[0049] G(x) = A*exp((xB)^2 / C^2) + D

[0050] In the above equation, A represents the curve height, B represents the coordinates of the curve center, C represents the standard deviation, and D represents the baseline height.

[0051] The edge position of lithium-ion battery 2 is the B parameter in the formula. Therefore, by using Gaussian fitting, we can overcome the pixel limitation and obtain the precise center coordinates, which is the X position of the left edge of lithium-ion battery 2. L .

[0052] 3) Using the method described above, obtain the right edge position X of lithium-ion battery 2. R At any angle θ i arbitrary height H i The diameter d of the lithium-ion battery at the location 2 i It can be represented as d i =X R -X L .

[0053] Volume reconstruction algorithms include:

[0054] The d obtained using the aforementioned edge fitting algorithm i It is possible to further calculate the angle θ at any angle. i The formula for calculating the volume unit of lithium-ion battery 2 is as follows:

[0055]

[0056] In the above formula, V i (d i ) indicates that the battery has rotated through any angle θ. i The volume unit contained in time, N step This represents the total number of steps the battery takes to complete one revolution (N). Step =400 (the same below), N H The corresponding battery height occupies 700 pixels (N) H =700), △H represents 1 pixel (taken as 1 in calculation), π is pi, d i Represents any angle θ i arbitrary height H i The diameter of the lithium-ion battery 2 at that location.

[0057] Furthermore, with the assistance of the battery rotation module 4, the lithium-ion battery 2 under test rotates 0.9° each time, and 400 rotations constitute a complete cylinder. Each rotation sweeps across a cylinder with a conical base, the area of ​​which is 1 / 400th of the base circle. Therefore, the volume unit V of the lithium-ion battery 2 under test at different angles is obtained. i Then, the three-dimensional morphology of the battery can be reconstructed, and the volume V of the lithium-ion battery 2 under test can be obtained by integration. The specific calculation formula is as follows:

[0058]

[0059] In the above formula, V represents the volume of the lithium-ion battery. i The meaning is the same as before, indicating that the battery rotates through any angle θ. i The volume unit contained in time, N Step This corresponds to 400 angles the battery has rotated through.

[0060] Thus, the volume V of battery 2 at any given time has been calculated. As the battery charging and discharging process proceeds, the volume of the battery in different states can be obtained using the above method.

[0061] Step 4) Establish real-time battery volume evolution and electrical curves during charging and discharging, and output them to monitor 6; electrical performance includes, but is not limited to, voltage, SOC, and SOH;

[0062] Step 5) Based on the results obtained in Step 4), detect the volume of the lithium-ion battery under test to predict the battery's electrical performance, which includes, but is not limited to, voltage, SOC, and SOH.

[0063] After the battery charge and discharge test is completed, the battery test system 8, function generator 9, and DC power supply 10 are turned off in sequence. At this time, the camera 3 stops image acquisition, the battery 2 stops rotating, and then the power supply of the camera 3 and the light source 1 is turned off, and the test ends.

[0064] Test case

[0065] Taking the ICR18650 lithium-ion battery as an example, according to the method described in Example 3, accurate battery volume evolution, SOC, and SOH curves can be obtained. Furthermore, according to the method described in this example, as... Figure 10 As shown, the morphological changes of the battery during charge and discharge tests can be further obtained.

[0066] Specifically, Figure 9 The curves reflect the relationship between battery volume and voltage, showing a positive correlation between the evolution of battery volume and voltage during charging and discharging.

[0067] exist Figure 10 The diagram illustrates the morphology of a lithium-ion battery at SOC = 0% (fully discharged state) and SOC = 100% (fully charged state). Lighter colors in the diagram represent greater morphological expansion, while darker colors represent greater morphological contraction. Figure 10 We can further observe the non-uniform volume change on the battery surface during charging and discharging, which indirectly verifies that the volume expansion of lithium-ion batteries is not uniform, and the degree of expansion varies greatly at different angles. Therefore, it is impossible to deduce the true volume of a lithium-ion battery from the diameter at a certain angle. Thus, obtaining the true volume of a lithium-ion battery during charging and discharging in real time is necessary to more accurately predict its true electrical parameters; otherwise, the error will be large.

[0068] To correlate battery volume with lifespan, we extracted the state of harm (SOH) and average volume change percentage for each charge-discharge cycle, calculated as follows:

[0069] SOH = Current cycle battery capacity / Standard battery capacity;

[0070] Average volume change percentage = ((average volume of the current cycle battery / average volume of the first cycle battery) - 1) * 100%;

[0071] The results are as follows Figure 11 As shown in the figure, we can see that as charge-discharge cycles continue, battery life gradually decreases, corresponding to a gradual increase in average battery volume, and the two have a very strong linear correlation. Therefore, we can monitor battery life by monitoring battery volume, for example... Figure 11 As shown in Figure c, when the average volume of the battery increases by 0.04%, it is known that the battery's State of Health (SOH) has decreased by approximately 10%. Therefore, if a battery is defined as needing to be discarded when its SOH declines to below 20%, it is only necessary to monitor a battery volume increase of 0.32%. This lays a solid foundation for further prediction of battery life.

Claims

1. A lithium-ion battery volume detection device based on optical imaging, characterized in that, The device includes: The optical imaging module uses light-emitting diodes as a light source and employs projection imaging to perform real-time optical imaging of the battery diameter on the electronic coupling element. The battery rotation module is used to drive the battery to rotate continuously at a preset speed to measure the battery diameter at different angles, thereby reconstructing the accurate volume of the battery; the battery rotation module is configured to allow the rotation and charge / discharge cycle of the lithium-ion battery to occur simultaneously. A battery charge / discharge module is used to perform charge / discharge cycles on lithium-ion batteries and monitor their electrical parameters. The optoelectronic synchronization module includes a function generator, a DC power supply, and a stepper motor controller. The DC power supply powers the stepper motor, and the function generator outputs a synchronous waveform to the stepper motor controller and the electronic coupling element, so that the electronic coupling element acquires one frame of image every time the stepper motor rotates a fixed angle, and so on. The real-time monitoring module includes a monitor and a computer host. The computer host is used to acquire the projected image of the lithium-ion battery delivered by the electronic coupling element in real time, and processes the image through edge localization and volume reconstruction methods to obtain the volume of the lithium-ion battery under test in real time. The volume evolution curve and electrical change curve of the lithium-ion battery during the charging and discharging process are output to the monitor in real time.

2. The lithium-ion battery volume detection device according to claim 1, characterized in that, The battery rotation module includes a battery rotation fixture, which includes a stepper motor, a lower conductive ring fixedly connected to the stepper motor shaft, an upper conductive ring axially corresponding to the lower conductive ring, at least one upper brush holder electrically connected to the upper conductive ring, and at least one lower brush holder electrically connected to the lower conductive ring. The upper and lower conductive rings are respectively inserted into the upper and lower ends of the battery. The stepper motor drives the lithium-ion battery and the upper and lower conductive rings to rotate circumferentially through the lower conductive ring. Wires are connected to the upper and lower brush holders respectively. Due to their own conductivity, the electricity on the wires can be directly conducted to the upper and lower conductive rings through the upper and lower brush holders, so that when the upper and lower conductive rings rotate, the upper and lower brush holders and their wires do not rotate, thus achieving electrical connection.

3. The lithium-ion battery volume detection device according to claim 2, characterized in that, The stepper motor is equipped with multiple vertically extending side rods, and the top of the multiple side rods is connected to a top plate. The space formed by the multiple side rods and the top plate is used to accommodate the upper conductive coil, the lower conductive coil, and the lithium-ion battery. The upper brush holder and the lower brush holder pass through the upper and lower sides of the multiple side rods respectively to connect with the upper conductive coil and the lower conductive coil.

4. The lithium-ion battery volume detection device according to claim 2, characterized in that, The upper negative electrode washer, the copper negative electrode washer, and the lower negative electrode washer are assembled with long screws to form a lower conductive ring; the upper positive electrode washer, the copper positive electrode washer, and the lower positive electrode washer are assembled with long screws to form an upper conductive ring.

5. The lithium-ion battery volume detection device according to claim 1, characterized in that, The battery rotation module includes a battery rotation clamp, which includes a stepper motor, a coupling connected to the stepper motor shaft, and a conductive clamp. The conductive clamp is axially aligned with the coupling. The upper and lower ends of the lithium-ion battery are respectively inserted into the conductive clamp and the coupling. The stepper motor drives the coupling and the conductive clamp to rotate circumferentially together. The conductive clamp has a conductive top and a conductive sidewall. The conductive top and the conductive sidewall are respectively provided with a top conductive hole and a side conductive hole, and wires are connected to the top conductive hole and the side conductive hole.

6. The volume detection device according to claim 1, characterized in that, d obtained using edge localization method i , through d i Further calculations are performed at any angle θ i The formula for calculating the volume unit of a lithium-ion battery is as follows: ； In the above formula, V i (d) i ) indicates that the battery has rotated through any angle θ. i The volume unit contained in time, N step N represents the total number of steps the battery takes to complete one revolution. H The corresponding battery height occupies 700 pixels, d i Represents any angle θ i arbitrary height H i The diameter of the lithium-ion battery at that location, where △H represents 1 pixel, and is taken as 1 during calculation; By measuring the diameter of the lithium-ion battery at different angles, the three-dimensional morphology is reconstructed using these diameters, and the volume V of the lithium-ion battery under test is obtained by integration. The specific calculation formula is as follows: ； In the above formula, V represents the volume of the lithium-ion battery, and θ i This indicates the diameter of the battery at different angles. As the battery is charged and discharged, its volume in different states can be obtained.

7. The application of the apparatus of claim 1 in detecting battery volume and predicting electrical performance, wherein the electrical performance includes voltage, SOC, or SOH.

8. The application as described in claim 7, comprising the following steps: Step 1) The entire test is conducted in a constant temperature chamber to ensure a constant ambient temperature; first, turn on the LED light source to preheat; then turn on the camera and set an appropriate exposure time; next, turn on the monitor, computer host, battery testing system, function generator and DC power supply in sequence. Step 2) Use a function generator to input the same waveform to the camera and the stepper motor, so that the camera starts to acquire images and the lithium-ion battery starts to rotate at a fixed speed, in order to obtain the diameter of the battery at different angles; at the same time, the battery testing system performs charge and discharge tests on the lithium-ion battery. Step 3) Obtain high-precision edge position information of the lithium-ion battery through the projected image, and obtain the diameter information of the lithium-ion battery through the edge positioning method; then obtain the diameter information of the battery at different angles by rotating the battery rotating fixture, and obtain the volume of the battery through the volume reconstruction algorithm. Step 4) Establish real-time battery volume evolution and electrical curves during charging and discharging, and output them to the monitor; Step 5) Based on the results obtained in Step 4), detect the volume of the lithium-ion battery under test to predict the battery's electrical performance, which includes, but is not limited to, voltage, SOC, and SOH.

9. A lithium-ion battery volume detection mechanism based on optical imaging, characterized in that, This organization includes: The optical imaging module uses light-emitting diodes as a light source and employs projection imaging to perform real-time optical imaging of the battery diameter on the electronic coupling element. The battery rotation module is used to drive the battery to rotate continuously at a preset speed to measure the battery diameter at different angles, thereby reconstructing the accurate volume of the battery. The photoelectric synchronization module includes a function generator, a DC power supply, and a stepper motor controller. The DC power supply powers the stepper motor, and the function generator outputs a synchronization waveform to the stepper motor controller and an electronic coupling element, so that the electronic coupling element acquires a frame of image every time the stepper motor rotates a fixed angle, and so on. The real-time monitoring module includes a monitor and a computer host. The computer host is used to acquire projected images of the lithium-ion battery delivered by the electronic coupling element in real time, and to process the images through edge localization and volume reconstruction methods to obtain the volume of the lithium-ion battery under test in real time. The volume evolution curve of the lithium-ion battery during the charging and discharging process is then output on the monitor in real time.

Images