A lithium ion battery external tab vibration detection method based on ultrasonic detection

Abstract

This invention discloses a method for detecting vibration of external electrodes in lithium-ion batteries based on ultrasonic testing. An ultrasonic pulse receiving piezoelectric plate is fixed to the surface of the lithium-ion battery. The battery is held in place using a charging / discharging instrument. During charging and discharging, the receiving piezoelectric plate receives ultrasonic signals passing through the battery and uploads them to a signal processing unit. A vibration-damping material is added between the clamp and the electrode as a control group. Alternatively, the charging / discharging instrument can be removed, and an ultrasonic pulse emitting piezoelectric plate can be fixed to the electrode. A signal generator drives the emitting piezoelectric plate to emit ultrasonic guided waves, simulating clamp vibration. The ultrasonic guided waves propagate through the battery, are received by the receiving piezoelectric plate, and converted into a response signal, which is then uploaded to the signal processing unit for analysis. This method enables real-time, non-destructive, online detection of electrode-transmitted vibration. It is low-cost, easy to integrate, and provides precise detection paths, which can be used to improve the accuracy of battery experiments and the safety early warning capabilities of battery management systems.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery testing technology, specifically a method for detecting the vibration of external electrodes of lithium-ion batteries based on ultrasonic testing. Background Technology

[0002] Lithium-ion batteries are widely used in many key fields such as electric vehicles and consumer electronics. The rapid expansion of the market has made their safety and reliability, especially the safety of power batteries, a focus of attention. In actual operation, batteries are often subjected to complex mechanical stress environments, and vibration can cause internal structural damage, loose connections, or even thermal runaway. During related experiments, such as ultrasonic testing and diaphragm stress testing, it is also necessary to check and eliminate interference from external vibrations to prevent affecting the stability of the results. Therefore, real-time monitoring of the battery's external conditions (especially vibration) is required.

[0003] To comprehensively assess the state of batteries under actual operating conditions and enhance battery safety testing, many studies have incorporated mechanical vibration testing. For example, image acquisition devices (such as cameras) are used to capture image sequences of battery packs during vibration testing, thereby determining whether there are potential safety hazards due to relative displacement or deformation of internal cells; accelerometers are used to collect road spectrum data for battery pack vibration testing; and laser vibrometers are also used to collect the dynamic response of batteries under different vibration spectra. These methods collectively provide crucial data support for vibration and safety analysis of batteries in complex environments.

[0004] However, the aforementioned technologies still have certain limitations. Image acquisition equipment observes macroscopic physical deformation and external vibration environments, but cannot detect high-frequency, microscopic mechanical vibrations that are transmitted into the battery through specific paths such as electrodes. Furthermore, these systems are complex and costly. While accelerometers can sense overall battery vibration, they cannot assess how external vibrations are transmitted to the battery through specific paths (such as electrodes). Precision instruments such as laser testers are expensive, complex to operate, and difficult to integrate into actual battery management systems or online experimental platforms.

[0005] Therefore, there is still a great need for research and development of low-cost and non-destructive methods for detecting electrode vibration. Summary of the Invention

[0006] The purpose of this invention is to provide a method for detecting the vibration of external electrodes of lithium-ion batteries based on ultrasonic testing, comprising the following steps:

[0007] S1. An ultrasonic pulse receiving piezoelectric element is fixed on the surface of a lithium-ion battery. The ultrasonic pulse receiving piezoelectric element is connected to a signal processing unit.

[0008] S2. Use a charging and discharging instrument to clamp the electrodes of the lithium-ion battery.

[0009] During the charging and discharging process of the lithium-ion battery, vibration signal I is collected by the piezoelectric element through ultrasonic pulse receiver and uploaded to the signal processing unit.

[0010] S3. Add vibration damping material between the clamp and the electrode of the charging and discharging instrument, and then collect vibration signal II by receiving the piezoelectric sheet through ultrasonic pulse and upload it to the signal processing unit.

[0011] S4. Extract the signal characteristics of vibration signal I and vibration signal II through the signal processing unit, and determine whether the amplitude of vibration signal II is significantly reduced compared with the amplitude of vibration signal I. If so, determine that the vibration of vibration signal I is transmitted from the external clamp and proceed to step S5. Otherwise, determine that the vibration of vibration signal I and / or vibration signal II is from other factors.

[0012] S5. Remove the charging / discharging instrument and assemble an ultrasonic pulse emitting piezoelectric element onto one of the electrodes of the lithium-ion battery. The ultrasonic pulse emitting piezoelectric element is connected to the signal generator.

[0013] S6. Start the signal generator. The signal generator outputs excitation pulses, which drive the ultrasonic pulse emitting piezoelectric sheet to emit ultrasonic guided waves, thereby simulating the vibration of the clamp.

[0014] At the same time, the signal generator uploads the trigger signal of the excitation pulse to the signal processing unit, which is recorded as the original signal.

[0015] S7. The ultrasonic guided wave propagates in the lithium-ion battery, is received by the ultrasonic pulse receiving piezoelectric element and converted into a response signal, which is then uploaded to the signal processing unit.

[0016] S8. The signal processing unit extracts signal feature I of the original signal and signal feature II of the response signal. Signal feature I and signal feature II are compared, and parameters in signal feature II that are not distorted after propagation through the lithium-ion battery and can still accurately reflect signal feature I are selected. These parameters are then used as key parameters for vibration detection.

[0017] Furthermore, in steps S4 and S8, the signal characteristics, signal characteristic I, and signal characteristic II include at least the signal frequency and the signal amplitude.

[0018] Furthermore, in step S4, the significant reduction refers to the amplitude of vibration signal I being attenuated by more than 80% compared to the amplitude of vibration signal I.

[0019] Furthermore, in step S4, the other factors are current fluctuations or electromagnetic interference.

[0020] Furthermore, in step S5, the ultrasonic pulse emitting piezoelectric sheet is fixed to the electrode using a clamp.

[0021] The clamp is used to apply a pressure perpendicular to the working surface of the ultrasonic pulse emitting piezoelectric sheet, thereby ensuring that the working surface of the ultrasonic pulse emitting piezoelectric sheet is completely in contact with the electrode.

[0022] Furthermore, in step S6, to simulate the vibration of the clamp, the excitation pulse output by the signal generator is a continuous sine wave, and the frequency range of the ultrasonic guided wave emitted by the ultrasonic pulse emitting piezoelectric sheet is 30-35kHz, with a peak voltage of 10V.

[0023] Furthermore, in step S6, the signal generator has two channels. One channel outputs an excitation pulse to drive the ultrasonic pulse emitting piezoelectric sheet to emit ultrasonic guided waves. The other channel is connected to the signal processing unit and outputs an electrical signal that is exactly the same as the excitation pulse as the original signal.

[0024] Furthermore, in step S1, the lithium-ion battery is a pouch battery.

[0025] Furthermore, in step S1, the ultrasonic pulse receiving piezoelectric sheet is a piezoelectric ceramic wafer, which is attached to the surface of the lithium-ion battery with AB glue.

[0026] Furthermore, the curing time of the ultrasonic pulse receiving piezoelectric sheet is greater than 6 hours.

[0027] The technical effects of this invention are undeniable, and its beneficial effects are as follows:

[0028] Compared to other methods for detecting mechanical interference in lithium-ion batteries, this invention, based on ultrasonic sensor detection, offers the advantages of being non-destructive and real-time. It can monitor abnormal vibrations in areas such as the battery electrodes, providing a better understanding of the battery's condition and allowing for the identification of vibration patterns and the implementation of appropriate mitigation measures before experiments. Furthermore, ultrasonic sensors are small, lightweight, and have a wide detection range, making them easy to integrate into battery management systems.

[0029] This method not only provides a new approach to battery state detection but also has multifaceted practical value for current battery experimental and testing systems. In ultrasonic testing experiments, high-frequency vibration interference is often regarded as noise, and the identification and differentiation capabilities of this method help to quickly identify the source of signal anomalies in the early stages of the experiment, improving the reliability of detection settings and data interpretation. Furthermore, for studies that aim to directly measure the dynamic stress borne by the electrodes and separator during battery charging and discharging, such as through in-situ measurements using tiny stress sensors, fiber Bragg gratings, or piezoelectric elements embedded inside the battery, vibrations from outside the electrodes can have a greater impact on the results, making early anomaly elimination essential. Attached Figure Description

[0030] Figure 1This is a schematic diagram of the method flow of the present invention;

[0031] Figure 2 This is a schematic front view of the device arrangement of the present invention;

[0032] Figure 3 This is a top view of the device arrangement of the present invention;

[0033] Figure 4 The continuous sinusoidal signal used in this invention;

[0034] Figure 5 To directly detect the voltage-time curve of the clamp vibration;

[0035] Figure 6 The voltage-time curve under a 30kHz excitation signal;

[0036] Figure 7 The voltage-time curve under a 35kHz excitation signal;

[0037] In the diagram: 1. Lithium-ion battery; 101. Electrode; 2. Charge / discharge instrument; 3. Ultrasonic pulse receiving piezoelectric element; 4. Ultrasonic pulse emitting piezoelectric element; 5. Signal generator; 6. Oscilloscope; 7. Calculator; 8. Signal processing unit. Detailed Implementation

[0038] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the scope of protection of the present invention.

[0039] Example 1:

[0040] Current technologies primarily focus on overall vibration analysis, with research on the key vibration transmission path, the "electrode," remaining largely unexplored.

[0041] In complex experimental environments such as high-rate charging and discharging and parallel testing of multiple devices, the sources of vibration mainly include: first, inherent vibrations during active operation of the equipment, such as vibrations generated by power converters, cooling fans, or mechanical pumps, which are transmitted to the clamps through the frame structure; second, micro-motions caused by electromagnetic induction, where alternating electromagnetic forces generated during high-current switching may induce minute vibrations in the clamps or connecting wires; and third, even when the equipment is not actively started, vibrations in the environment, such as those from nearby operating equipment, conduction through the floor, or disturbances caused by tension or swaying of the test harness, may be transmitted and amplified to the clamp end through the rigidly connected harness. These vibrations are directly transmitted to the battery electrodes through rigid connections, which not only severely interferes with and reduces the accuracy of experimental data based on voltage, ultrasound, etc., but may also pose a potential risk to the interface stability between the electrode and internal materials due to long-term mechanical stress transmission, yet are difficult to detect using traditional macroscopic detection methods.

[0042] The purpose of this invention is to overcome the shortcomings of existing battery external vibration detection technologies. Combining the relevant principles of ultrasonic guided wave battery detection, and utilizing its high sensitivity, low cost, and non-destructive testing characteristics, a method for detecting the vibration of lithium-ion battery electrodes is proposed.

[0043] A method for detecting vibration of external electrodes in lithium-ion batteries based on ultrasonic testing includes the following steps:

[0044] S1. An ultrasonic pulse receiving piezoelectric element 3 is fixed on the surface of the lithium-ion battery 1. The ultrasonic pulse receiving piezoelectric element 3 is connected to the signal processing unit 8.

[0045] S2. Use the charging and discharging instrument 2 to clamp the electrode 101 of the lithium-ion battery 1.

[0046] During the charging and discharging process of lithium-ion battery 1, vibration signal I is collected by piezoelectric element 3 via ultrasonic pulse receiver and uploaded to signal processing unit 8.

[0047] S3. Add vibration damping material between the chuck and electrode 101 of the charging and discharging instrument 2, and then collect vibration signal II through the ultrasonic pulse receiver piezoelectric plate 3 and upload it to the signal processing unit 8.

[0048] S4. The signal characteristics of vibration signal I and vibration signal II are extracted by the signal processing unit 8. It is determined whether the amplitude of vibration signal II is significantly reduced compared with the amplitude of vibration signal I. If so, it is determined that the vibration of vibration signal I is transmitted from the external clamp and proceeds to step S5. Otherwise, it is determined that the vibration of vibration signal I and / or vibration signal II is from other factors.

[0049] S5. Remove the charging / discharging instrument 2 and assemble an ultrasonic pulse emitting piezoelectric element 4 on one of the electrodes 101 of the lithium-ion battery 1. The ultrasonic pulse emitting piezoelectric element 4 is connected to the signal generator 5.

[0050] S6. Start signal generator 5. Signal generator 5 outputs excitation pulses to drive ultrasonic pulse emitting piezoelectric sheet 4 to emit ultrasonic guided waves, thereby simulating the vibration of the clamp.

[0051] At the same time, the signal generator 5 uploads the trigger signal of the excitation pulse to the signal processing unit 8, which is recorded as the original signal.

[0052] S7. The ultrasonic guided wave propagates in the lithium-ion battery 1, is received by the ultrasonic pulse receiving piezoelectric sheet 3 and converted into a response signal, which is then uploaded to the signal processing unit 8.

[0053] S8. The signal processing unit 8 extracts the signal feature I of the original signal and the signal feature II of the response signal. The signal feature I and the signal feature II are compared, and the parameter in the signal feature II that is not distorted after being propagated by the lithium-ion battery 1 and can still accurately reflect the signal feature I is selected. This parameter is used as the key parameter for vibration detection.

[0054] For example, if the frequency of the response signal is the same as the frequency of the original signal, or if it clearly shows a relationship that is easy to deduce, then the frequency can be used as a key parameter. In subsequent testing, the frequency of the vibration can be directly determined, thereby identifying the source of the vibration (low-frequency platform vibration or high-frequency power supply ripple, etc.) or analyzing its impact on the battery (the higher the vibration frequency, the smaller the attenuation coefficient, the farther the propagation distance, and the greater the impact on the stability of the internal materials).

[0055] Example 2:

[0056] The main structure of this embodiment is the same as that of embodiment 1. Furthermore, in steps S4 and S8, the signal features, signal feature I, and signal feature II include at least signal frequency and signal amplitude.

[0057] Example 3:

[0058] The main structure of this embodiment is the same as any one of embodiments 1 to 2. Further, in step S4, the significant reduction means that the amplitude of vibration signal I is attenuated by more than 80% compared to the amplitude of vibration signal I.

[0059] Example 4:

[0060] The main structure of this embodiment is the same as any one of embodiments 1 to 3. Furthermore, in step S4, the other factors are current fluctuations or electromagnetic interference.

[0061] Example 5:

[0062] The main structure of this embodiment is the same as any one of embodiments 1 to 4. Further, in step S5, the ultrasonic pulse emitting piezoelectric sheet 4 is fixed on the electrode sheet 101 using a clamp.

[0063] The clamp is used to apply a pressure perpendicular to the working surface of the ultrasonic pulse emitting piezoelectric sheet 4, thereby ensuring that the working surface of the ultrasonic pulse emitting piezoelectric sheet 4 is completely in contact with the electrode 101.

[0064] Example 6:

[0065] The main structure of this embodiment is the same as any one of embodiments 1 to 5. Further, in step S6, in order to simulate the vibration of the clamp, the excitation pulse output by the signal generator 5 is a continuous sine wave, and the frequency range of the ultrasonic guided wave emitted by the ultrasonic pulse emitting piezoelectric sheet 4 is 30-35kHz, and the peak voltage is 10V.

[0066] Example 7:

[0067] The main structure of this embodiment is the same as any one of embodiments 1 to 6. Further, in step S6, the signal generator 5 has two channels. One channel outputs an excitation pulse to drive the ultrasonic pulse emitting piezoelectric sheet 4 to emit ultrasonic guided waves. The other channel is connected to the signal processing unit 8 and is used to output an electrical signal that is exactly the same as the excitation pulse as the original signal.

[0068] Example 8:

[0069] The main structure of this embodiment is the same as any one of embodiments 1 to 7. Furthermore, in step S1, the lithium-ion battery 1 is a pouch battery.

[0070] Example 9:

[0071] The main structure of this embodiment is the same as any one of embodiments 1 to 8. Further, in step S1, the ultrasonic pulse receiving piezoelectric sheet 3 is a piezoelectric ceramic wafer, and the piezoelectric ceramic wafer is attached to the surface of the lithium-ion battery 1 with AB glue.

[0072] Example 10:

[0073] The main structure of this embodiment is the same as that of embodiment 9. Furthermore, the curing time of the ultrasonic pulse receiving piezoelectric sheet 3 is greater than 6 hours.

[0074] Example 11:

[0075] The main structure of this embodiment is the same as any one of embodiments 1 to 10. Further, this method first determines the attachment position of the ultrasonic guided wave sensor (ultrasonic pulse receiving piezoelectric piece 3), and then connects the ultrasonic guided wave sensor to an oscilloscope 6 or other instrument in real time to reflect the induced waveform. Then, a charging / discharging device is connected, and the acquisition device is activated to record the waveform characteristics, which can reflect the vibration of the electrode. Specifically, the purpose of this method is achieved through the following technical solution: A method for detecting the vibration of a high-lithium-ion battery electrode based on an ultrasonic guided wave sensor, comprising the following steps:

[0076] 1) Select a lithium-ion battery 1, fix the ultrasonic pulse receiving piezoelectric piece 3 on the surface of one side of the lithium-ion battery 1, and connect the sensor to the oscilloscope 6;

[0077] 2) Select several high-rate lithium-ion batteries 1 as described in 1), which are integrated with ultrasonic pulse receiving piezoelectric elements 3, and connect them to the charging and discharging instrument clamp. During the process, ultrasonic pulse receiving piezoelectric elements 3 are used to collect ultrasonic guided wave signals online.

[0078] 4) During the actual charging and discharging process of lithium-ion battery 1, ultrasonic pulse receiving piezoelectric sheet 3 periodically receives ultrasonic signals passing through lithium-ion battery 1, and signal acquisition software collects and calculates the waveform and amplitude of ultrasonic signals.

[0079] 5) Add a certain amount of damping material between the electrode 101 and the clamp, observe the attenuation of the vibration waveform, and verify the position of the sound wave originating from the electrode.

[0080] 6) Place the ultrasonic pulse emitting piezoelectric sheet 4 as the emitting end on the electrode 101 (positive or negative electrode sheet) to emit a predetermined vibration signal, and use the above-mentioned equipment to receive the ultrasonic signal and analyze and compare the detection effect.

[0081] The electrode 101 is subjected to high-frequency vibrations from the charging / discharging clamps, which are transmitted to other parts of the battery and received. The ultrasonic pulse receiver 3 senses the signal and sends it to the signal processing software for real-time acquisition and processing of the ultrasonic signal. The oscilloscope 6 acquires the ultrasonic guided wave with a frequency setting of 30 or 35 kHz and an amplitude of 10 V.

[0082] The discovery of this method stemmed from an experiment on lithium-ion battery state detection based on ultrasonic guided waves. The experiment required a pair of ultrasonic pulse piezoelectric plates as transmitting and receiving sensors, respectively. However, the received waveform displayed on oscilloscope 6 exhibited continuous fluctuations. The unstable waveform caused significant differences in amplitude and shape between each acquired signal, failing to reflect accurate results. After ruling out other possible problems, it was determined that the abnormal fluctuations originated from the high-frequency vibration of the charging / discharging clamps on the electrode. The superposition of the transmitted and transmitted ultrasonic signals produced the fluctuating received signal. To eliminate the influence of the charging / discharging current, different insulating materials were applied to the electrode for observation. It was found that the fluctuations still existed, thus confirming that this method can detect high-frequency vibrations transmitted from the electrode and calculate its frequency and other characteristics.

[0083] Example 12:

[0084] The main structure of this embodiment is the same as any one of embodiments 1 to 11. Furthermore, a method for detecting the vibration of the external electrode of a lithium-ion battery based on ultrasonic testing includes the following steps:

[0085] S1. An ultrasonic pulse receiving piezoelectric piece 3 is fixed to one end of the surface of the lithium-ion battery 1 and connected to the signal processing unit 8; the ultrasonic guided wave sensor uses a piezoelectric ceramic wafer and is fixed to the surface of the lithium-ion battery with AB glue, and the curing time is not less than 5 hours.

[0086] S2. Connect the lithium-ion battery 1 to the charging and discharging instrument 2, and collect the original vibration signal through the ultrasonic pulse receiving piezoelectric plate 3; then add vibration damping material between the electrode 101 and the charging and discharging clamp, and collect the vibration signal again. By comparing the characteristics of the two signals, it is determined whether the vibration is transmitted from the external clamp.

[0087] The extracted signal features include at least signal frequency and amplitude, and external vibration interference is identified by detecting abnormal fluctuations or attenuation of the signal amplitude relative to a reference value.

[0088] S3. An ultrasonic pulse emitting piezoelectric element 4 is clamped on the electrode 101. The ultrasonic pulse emitting piezoelectric element 4 on the electrode 101 is driven by the signal generator 5 to emit continuous ultrasonic guided waves to simulate the vibration of the clamp. The response signal after passing through the lithium-ion battery 1 is received by the ultrasonic pulse receiving piezoelectric element 3.

[0089] The excitation pulse emitted by the signal generator 5 is a continuous sine wave, and the frequency of the ultrasonic guided wave is in the range of 30-35kHz, with a peak voltage of 10V.

[0090] S4. The response signal is acquired and processed by the signal processing unit 8, and signal features are extracted;

[0091] S5. Based on the changes in signal characteristics, determine whether there is high-frequency mechanical vibration transmitted from the outside to the inside through the battery electrode 101, and the degree of similarity between the characteristics of the received signal and the original signal.

[0092] The object detected and judged in this invention is the mechanical vibration generated by an external source and transmitted to the inside of the battery through the electrode, rather than the vibration displacement between battery cells.

[0093] This invention focuses on obtaining vibration characteristics using the principles of ultrasonic testing, rather than using instruments such as accelerometers or laser vibrometers.

[0094] Compared to other methods, this innovation utilizes ultrasonic principles for battery vibration detection, precisely focusing on the critical physical path of the "electrode." This improvement reduces vibration detection costs and simplifies the operation process. Compared to traditional methods relying on macroscopic detection techniques such as image analysis and accelerometer sensing, this invention achieves a leap from overall observation to microscopic path localization. Furthermore, the small-volume sensor facilitates integration into existing battery testing or management systems, enabling cost-effective online diagnostics. In terms of practicality, this method combines non-destructive and real-time characteristics with a simple operation process. It provides a new and effective tool for battery experimental research, product testing, and safety inspection.

[0095] Example 13:

[0096] The main structure of this embodiment is the same as any one of embodiments 1 to 12. Further, see [link to embodiment 1]. Figure 1 A method for detecting the vibration of external electrodes of lithium-ion batteries based on ultrasonic testing includes the following specific steps:

[0097] 1) Select a number of lithium-ion batteries 1, wherein the lithium-ion batteries 1 are soft-pack batteries;

[0098] The ultrasonic pulse receiving piezoelectric element 3 is fixed to one end of the same surface of the lithium-ion battery 1 and cured. AB glue can be used for fixing, and the curing time is generally not less than 5 hours. Subsequently, the ultrasonic pulse receiving piezoelectric element 3 is connected to the signal processing unit 8 (oscilloscope 6, calculator 7) for communication.

[0099] 2) Connect the charging and discharging equipment, and you can observe the real-time vibration in oscilloscope 6.

[0100] Two control groups were set up: one with vibration reduction and one without.

[0101] For the vibration damping group, insulating vibration damping materials such as foam are placed at the contact position between the clamp and the electrode 101 to eliminate electrical signal interference. By comparing the two, it is determined that the detected signal originates from the vibration transmitted from the clamp to the electrode. The signal processing unit 8 is then activated to extract the signal, and the results of both are presented in the same graph to compare the amplitude changes.

[0102] 3) Then, remove the charging and discharging equipment, clamp and fix the ultrasonic pulse emitting piezoelectric element 4 onto the positive electrode, and then establish a communication connection between the ultrasonic pulse emitting piezoelectric element 4 and the signal generator 5. The signal generator 5 periodically sends a specified signal to control the ultrasonic pulse emitting piezoelectric element 4 to emit continuous excitation to simulate the vibration transmission of the clamp. The vibration signal is then received again by the ultrasonic pulse receiving piezoelectric element 3. The signal processing unit 8 extracts the waveform to obtain the original signal and the received signal, verifying the vibration detection effect of the device. Specifically, the amplitude and frequency of the two ultrasonic signals are compared to observe the magnitude of the reception error.

[0103] Specifically, the signal generator 5 excites the ultrasonic pulse emitting plate with a continuous sine wave, such as... Figure 4 As shown. The ultrasonic guided wave frequency is set to 30 and 35 kHz, and the peak voltage is 10 V. This is to match the detected vibration frequency of the clamp and simulate the real vibration situation.

[0104] This can be obtained through data processing. For example... Figure 5 After connecting the charging and discharging clamp, a vibration signal can be detected. After implementing vibration reduction measures, the vibration amplitude is greatly reduced, but the frequency remains the same at approximately 31.13 kHz, further proving that the detected signal originates from the vibration on the electrode.

[0105] Secondly, the detection status of actively transmitted signals, such as Figure 6 Under both 30kHz and 35kHz excitation, the detected vibration frequencies remained consistent, further verifying that this method can effectively detect electrode vibration, especially with precise detection of frequency characteristics. Furthermore, due to vibration attenuation, the amplitude decreased overall after passing through a certain path and the attenuation decreased as the original signal frequency increased, demonstrating the method's advantage in detecting high-frequency vibrations.

[0106] In this patent embodiment, an LFP soft-pack battery with a capacity of 2300mAh and dimensions of 95.5×46×7.1 (mm) was used as the experimental object. The experiment was conducted at room temperature (25℃). The ultrasonic guided wave sensor used according to the method described in this invention is a piezoelectric ceramic wafer manufactured by Guangdong Audiway Sensing Technology Co., Ltd., with a diameter of 14mm and a thickness of 2mm, product model AW5Y14213M. In this embodiment, after adding damping material, a decrease in amplitude indicates that the vibration source is indeed the charging / discharging clamp. Subsequent verification of signal frequency consistency proves the good effect of vibration detection. Currently, there is a lack of research and exploration on the specific component of the electrode in vibration detection of lithium-ion batteries. Therefore, this method can serve as an effective means for analyzing the vibration and conduction of the external electrode of the battery.

[0107] The significance of this method lies in three aspects: First, it enables interference source tracing, clearly distinguishing whether data anomalies originate from changes in the battery's internal state or mechanical interference introduced by external fixtures, thereby improving the reliability of the experiment and the accuracy of the conclusions. Second, it provides preventative diagnosis, enabling the detection and evaluation of the mechanical stability of the entire test platform (including the clamps) even before formal testing begins, preventing problems before they occur. Third, it expands vibration detection tools, providing a convenient and low-cost solution for analyzing the microscopic mechanical vibration inside the battery from the specific perspective of electrode conduction.

[0108] Furthermore, this method can be extended into a real-time, non-invasive tool for detecting the internal mechanical state of batteries. By capturing high-frequency vibration signals transmitted through the electrodes, changes in the battery's internal structure can be indirectly reflected. For example, changes in the received signal amplitude may reflect the expansion and contraction of the electrode materials (the expansion and contraction of the electrode materials will change the residual bubbles inside the battery, thus affecting the wave attenuation characteristics). The flight time and amplitude of the received signal may reflect changes in the microstructure caused by the evolution of the interface contact state (good contact ensures that the parts fit tightly together, which is conducive to the propagation of high-frequency vibrations, while when the contact deteriorates, the wave will reflect and refract back and forth in the gaps, causing mode conversion and increasing the attenuation coefficient). This provides a dynamic observation window for studying the mechanical degradation mechanism of batteries during cycling, making up for the lack of temporal continuity in traditional static disassembly analysis.

Claims

1. A method for detecting vibration of external electrodes of lithium-ion batteries based on ultrasonic testing, characterized in that, Includes the following steps: S1. An ultrasonic pulse receiving piezoelectric piece (3) is fixed on the surface of the lithium-ion battery (1); the ultrasonic pulse receiving piezoelectric piece (3) is connected to the signal processing unit (8). S2. Use a charging and discharging instrument (2) to clamp the electrode (101) of the lithium-ion battery (1). During the charging and discharging process of the lithium-ion battery (1), the vibration signal I is collected by the ultrasonic pulse receiving piezoelectric plate (3) and uploaded to the signal processing unit (8). S3. Add vibration damping material between the clamp and the electrode (101) of the charging and discharging instrument (2), and then collect vibration signal II through the ultrasonic pulse receiving piezoelectric sheet (3) and upload it to the signal processing unit (8). S4. The signal characteristics of vibration signal I and vibration signal II are extracted by the signal processing unit (8). It is determined whether the amplitude of vibration signal II is significantly reduced compared with the amplitude of vibration signal I. If so, it is determined that the vibration of vibration signal I is transmitted from the external clamp and proceeds to step S5. Otherwise, it is determined that the vibration of vibration signal I and / or vibration signal II is from other factors. S5. Remove the charging and discharging instrument (2) and assemble an ultrasonic pulse emitting piezoelectric piece (4) on a certain electrode (101) of the lithium-ion battery (1); the ultrasonic pulse emitting piezoelectric piece (4) is connected to the signal generator (5). S6. Start the signal generator (5). The signal generator (5) outputs an excitation pulse, which drives the ultrasonic pulse emitting piezoelectric sheet (4) to emit ultrasonic guided waves, thereby simulating the vibration of the clamp. At the same time, the signal generator (5) uploads the trigger signal of the excitation pulse to the signal processing unit (8), which is recorded as the original signal; S7. The ultrasonic guided wave propagates in the lithium-ion battery (1), is received by the ultrasonic pulse receiving piezoelectric sheet (3) and converted into a response signal, which is then uploaded to the signal processing unit (8). S8. The signal processing unit (8) extracts the signal feature I of the original signal and the signal feature II of the response signal. The signal feature I and the signal feature II are compared and the parameters in the signal feature II that are not distorted after being propagated by the lithium-ion battery (1) and can still accurately reflect the signal feature I are selected. These parameters are used as the key parameters for vibration detection.

2. The method for detecting vibration of external electrode sheets of lithium-ion batteries based on ultrasonic testing according to claim 1, characterized in that: In steps S4 and S8, the signal characteristics, signal characteristic I, and signal characteristic II include at least the signal frequency and the signal amplitude.

3. The method for detecting vibration of external electrode sheets of lithium-ion batteries based on ultrasonic testing according to claim 1, characterized in that: In step S4, the significant reduction means that the amplitude of vibration signal I is attenuated by more than 80% compared to the amplitude of vibration signal I.

4. The method for detecting vibration of external electrode sheets of lithium-ion batteries based on ultrasonic testing according to claim 1, characterized in that: In step S4, the other factors are current fluctuations or electromagnetic interference.

5. The method for detecting vibration of external electrode sheets of lithium-ion batteries based on ultrasonic testing according to claim 1, characterized in that: In step S5, the ultrasonic pulse emitting piezoelectric sheet (4) is fixed onto the electrode sheet (101) using a clamp; The clamp is used to apply a pressure perpendicular to the working surface of the ultrasonic pulse emitting piezoelectric sheet (4) to the ultrasonic pulse emitting piezoelectric sheet (4), thereby ensuring that the working surface of the ultrasonic pulse emitting piezoelectric sheet (4) is completely in contact with the electrode (101).

6. The method for detecting vibration of external electrode sheets of lithium-ion batteries based on ultrasonic testing according to claim 1, characterized in that: In step S6, to simulate the vibration of the clamp, the excitation pulse output by the signal generator (5) is a continuous sine wave, and the frequency range of the ultrasonic guided wave emitted by the ultrasonic pulse emitting piezoelectric sheet (4) is 30-35kHz, with a peak voltage of 10V.

7. The method for detecting vibration of external electrode sheets of lithium-ion batteries based on ultrasonic testing according to claim 1, characterized in that: In step S6, the signal generator (5) has two channels. One channel outputs an excitation pulse to drive the ultrasonic pulse emitting piezoelectric sheet (4) to emit ultrasonic guided waves. The other channel is connected to the signal processing unit (8) to output an electrical signal that is exactly the same as the excitation pulse as the original signal.

8. The method for detecting vibration of external electrode sheets of lithium-ion batteries based on ultrasonic testing according to claim 1, characterized in that: In step S1, the lithium-ion battery (1) is a pouch battery.

9. The method for detecting vibration of external electrode sheets of lithium-ion batteries based on ultrasonic testing according to claim 1, characterized in that: In step S1, the ultrasonic pulse receiving piezoelectric sheet (3) is a piezoelectric ceramic wafer, which is attached to the surface of the lithium-ion battery (1) with AB glue.

10. A method for detecting vibration of external electrode sheets of lithium-ion batteries based on ultrasonic testing according to claim 9, characterized in that: The curing time of the ultrasonic pulse receiving piezoelectric sheet (3) is greater than 6 hours.

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