Electrolyte infiltration state nondestructive detection device and detection method
The non-destructive testing device for electrolyte wetting status, which uses an acoustic probe module and a coupling module, solves the problem of difficulty in monitoring electrolyte wetting status in lithium-ion battery production. It achieves non-destructive and rapid detection of electrolyte wetting status, thereby improving battery quality and production efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-11
- Publication Date
- 2026-04-03
AI Technical Summary
Existing technologies lack effective online monitoring methods to detect the wetting state of electrolytes during lithium-ion battery production, making this process a "black box" that affects the battery's internal resistance, capacity, cycle life, and safety.
A non-destructive testing device for electrolyte wetting state, employing an acoustic probe module and a coupling module, acquires acoustic excitation and response signals at the battery's filling port using an acoustic exciter and microphone. Combined with the Helmholtz resonator resonator frequency equation, it achieves non-destructive, in-situ testing of the electrolyte wetting state.
It enables non-destructive and rapid detection of electrolyte immersion status, which can be completed in seconds or even milliseconds, ensuring 100% online inspection of every battery, improving product quality and production efficiency, and reducing costs.
Smart Images
Figure CN121783774A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery testing, and in particular to a non-destructive testing device and method for electrolyte wetting state. Background Technology
[0002] The wetting of the electrode plates with electrolyte is a critical process in lithium-ion battery production, and its quality directly determines the battery's internal resistance, capacity, cycle life, and safety. Currently, this process mainly relies on fixed settling times and lacks effective online monitoring methods, making it a "black box" process.
[0003] Existing characterization methods, such as gravimetric analysis, contact angle analysis, or offline dissection methods, cannot be used for online detection of sealed batteries. Large imaging equipment, such as X-ray CT, is expensive and difficult to integrate into production lines. Other methods, such as electrochemical impedance spectroscopy, may interfere with the battery formation process. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings and defects of the prior art and to provide a non-destructive testing device and method for electrolyte wetting state.
[0005] To achieve the above objectives, this application adopts the following solution:
[0006] A non-destructive testing device for electrolyte wetting state includes an acoustic probe module and a coupling module; the acoustic probe module includes an acoustic exciter, an acoustic receiver, and an intelligent signal processing and analysis module; the intelligent signal processing and analysis module is electrically connected to the acoustic exciter and the acoustic receiver.
[0007] The acoustic exciter is a loudspeaker; the acoustic receiver is a microphone.
[0008] The coupling module includes a coupling body for mounting the acoustic exciter and acoustic receiver; the coupling body is provided with a coupling head covering the battery filling hole.
[0009] The inner wall of the coupling body is filled with polyurethane foam sound-absorbing cotton, and a sealing ring is provided on the coupling head; a mechanical arm for applying pressure is provided on the top of the coupling body.
[0010] The present invention also includes a non-destructive testing method for electrolyte wetting state, using the aforementioned non-destructive testing device.
[0011] The non-destructive testing method for electrolyte wetting state is characterized by comprising the following steps:
[0012] 1) After being injected with electrolyte, the battery is transferred to the testing station, where the robotic arm pushes down the acoustic probe module to form a sealed coupling with the injection port;
[0013] 2) Apply an excitation signal and collect resonance peak frequency data. Specifically, this includes:
[0014] S1: At the battery's filling port, an acoustic excitation signal containing a specific resonant frequency range is applied using an acoustic exciter, and the acoustic response signal transmitted back through the filling port is synchronously acquired using an acoustic receiver; the resonant frequency range is obtained through the Helmholtz resonator resonant frequency equation; the Helmholtz resonator resonant frequency equation is... Where f is the resonant frequency, C is the speed of sound, A is the cross-sectional area of the injection hole, L is the effective length of the injection hole, and V is the cavity volume; C, A, and L are constants, V is a variable, f ranges from at least fmin to fmax, Vmax = 0.18*X, Vmin = 0.01*X, and X is the cell volume.
[0015] S2: Use the signal processing and analysis module to perform frequency domain analysis on the acquired response signal, calculate the system's frequency response function, and identify its main resonant frequency f;
[0016] S3: Repeat steps S1-S2 to obtain the curves of the main resonance frequency f corresponding to different injection times. In S3, if the curve of the main resonance frequency f changing with time shows a trend of first monotonically increasing and then decreasing, it is determined to be an over-injection condition. The wetting process is evaluated based on the magnitude and rate of frequency decrease.
[0017] If the resonant frequency f shows a monotonically decreasing trend after its first appearance in the curve of the main resonant frequency f over time, it is determined to be a routine injection condition, and the wetting process is evaluated based on the magnitude and rate of frequency decrease.
[0018] When the rate of change of the resonance rate approaches 0, it indicates that the infiltration is complete.
[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0020] 1. Non-destructive and in-situ testing: This invention uses the battery's inherent electrolyte injection port for acoustic excitation and acquisition, completely avoiding contact with the electrolyte and preventing damage to any battery components (such as the casing, electrodes, and separator). It is a truly non-destructive testing method. The testing process will not affect the battery's subsequent electrochemical performance.
[0021] 2. Highly efficient testing capabilities and low cost: A single measurement process can be completed within seconds or even milliseconds, making it extremely fast. This enables 100% online inspection of every battery, thus achieving high-quality quality control. The device has a simple structure, making it easy to install, maintain, and deploy on large-scale production lines.
[0022] In summary, this invention provides an unprecedented solution that successfully solves the long-standing problem of monitoring the electrolyte wetting process in the battery manufacturing industry in a low-cost, high-efficiency, and highly reliable manner. The resulting technical effects are a significant improvement in product quality, production efficiency, and intelligence level. Attached Figure Description
[0023] Figure 1 This is an overall schematic diagram of the non-destructive testing device for electrolyte wetting state of the present invention;
[0024] Figure 2 This is a schematic diagram of the acoustic probe module of the present invention;
[0025] Figure 3 This is a schematic diagram illustrating the usage process of the non-destructive testing device for electrolyte wetting state according to the present invention;
[0026] Figure 4 This is an identification diagram of the main resonance frequency f of the present invention;
[0027] Figure 5 This invention describes the variation trend and determination method of the main resonance frequency f.
[0028] Figure 6 This is a graph showing the variation of the main resonance frequency f during the immersion process of this invention;
[0029] Figure 7-8 This is a disassembled diagram of the battery immersed in the present invention. Detailed Implementation
[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
[0031] Figure 1-2 A non-destructive testing device for electrolyte wetting state is shown, including an acoustic probe module and a coupling module; Figure 2 The acoustic probe module shown includes an acoustic exciter, an acoustic receiver, and an intelligent signal processing and analysis module; the intelligent signal processing and analysis module is electrically connected to the acoustic exciter and the acoustic receiver. The acoustic exciter is a loudspeaker (piezoelectric loudspeaker); the acoustic receiver is a microphone.
[0032] Figure 1 The coupling module shown includes a coupling body 1 for mounting the acoustic exciter 2 and the acoustic receiver; the coupling body is provided with a coupling head 3 covering the battery filling hole. The inner wall of the coupling body is filled with polyurethane foam sound-absorbing cotton, and a sealing ring is provided on the coupling head; a mechanical arm for applying pressure is provided on the top of the coupling body.
[0033] The top of the coupling body is detachable and has corresponding speaker mounting holes for speaker wires and microphone mounting holes for microphone wires. The coupling head at the bottom of the coupling body couples with the liquid injection port and has a silicone sealing ring for a tight seal. The inner walls of the device are filled with polyurethane foam sound-absorbing cotton to prevent acoustic interference within the device cavity.
[0034] To use, first connect the speaker and microphone to the sound card, then connect the USB sound card to your phone or computer. Pass the speaker through... Figure 6 The device has a speaker mounting hole, through which the microphone passes and is mounted in a microphone mounting port. The phone or computer needs to have acoustic software installed, such as Audio Tool, which can simultaneously generate and receive sound.
[0035] The present invention also includes a non-destructive testing method for electrolyte wetting state, using the aforementioned non-destructive testing device.
[0036] Figure 3 The non-destructive testing method for electrolyte wetting state is shown, comprising the following steps:
[0037] 1) After being injected with electrolyte, the battery is transferred to the testing station, where the robotic arm pushes down the acoustic probe module to form a sealed coupling with the injection port;
[0038] 2) Apply an excitation signal and collect resonance peak frequency data. Specifically, this includes:
[0039] S1: At the battery's filling port, an acoustic excitation signal containing a specific resonant frequency range is applied using an acoustic exciter, and the acoustic response signal transmitted back through the filling port is synchronously acquired using an acoustic receiver; the resonant frequency range is obtained through the Helmholtz resonator resonant frequency equation; the Helmholtz resonator resonant frequency equation is... Where f is the resonant frequency, C is the speed of sound, A is the cross-sectional area of the injection hole, L is the effective length of the injection hole, and V is the cavity volume; C, A, and L are constants, V is a variable, f ranges from at least fmin to fmax, Vmax = 0.18*X, Vmin = 0.01*X, and X is the cell volume.
[0040] According to the Helmholtz resonator resonant frequency equation, c = 340 m / s. Given that the typical electrolyte inlet diameter of a battery cell is 3 mm, then A is 7.065 * 10⁻⁶ m / s. -6 m 2L is 0.003m. Due to energy density requirements, and after removing the volume occupied by structural components and electrode groups, the maximum remaining unoccupied space volume for vehicle-mounted and energy storage cells is 18% of the cell model volume. The cavity volume (V) is directly related to the electrolyte injection volume, but different injection coefficients will affect the cavity volume. However, the maximum remaining unoccupied space volume of 18% of the cell model volume is a constant. Vmax = 0.18 * X (cell volume) Vmin = 0.01 * X (cell volume)
[0041] For example, consider the currently commercially available energy storage series 314Ah-LP71173207 and passenger car 63.3Ah-LP3320584. The volume of the 314Ah energy storage is 2543ml, so its Vmax = 457ml and Vmin = 25ml. Substituting these data into the Helmholtz resonator resonant frequency equation, we get fmin = 122Hz and fmax = 525Hz. The volume of the 63.3Ah passenger car is 492ml, so its VMAX = 102ml and VMIN = 5ml. Substituting these values into the equation, we get fmin = 260Hz and fmax = 1175Hz.
[0042] For the LP2714897 model, with a capacity of 40Ah, according to the Helmholtz resonance frequency equation, fmin = 316Hz and fmax = 1857Hz are calculated. The signal control module is then set to a linear sweep frequency signal with a frequency range of 200Hz-2000Hz (this frequency needs to cover the calculated resonance frequency range) to drive the exciter to emit sound waves.
[0043] S2: Use the signal processing and analysis module to perform frequency domain analysis on the acquired response signal, calculate the system's frequency response function, and identify its main resonant frequency f; conduct tests on the battery cell after it has been left to stand for 2 hours after injection. Use the Audio tool software on a mobile phone to generate and receive sound, obtain the resonant frequency value based on the spectrum, and collect this spectrum value. Plot the response intensity frequency, and the receiver collects the response signal. Only when the input sound frequency matches the system's resonant frequency, indicating in-phase operation, will its loudness (amplitude) reach its maximum, thus determining its resonant frequency value. Figure 4 As shown, the peak value that appears at this moment is the resonant frequency value at this moment. Collect the peak value of this resonant frequency (the main resonant frequency f).
[0044] S3: Repeat steps S1-S2 to obtain the variation curve of the principal resonant frequency f corresponding to different injection times. Specifically, after two hours, repeat the above steps to obtain the second resonant frequency value. By continuously repeating the above steps and comparing the changes in the principal resonant frequency during the wetting process, the wetting state of the electrolyte can be characterized.
[0045] like Figure 5As shown in Figure S3, if the curve of the main resonant frequency f changing with time shows a trend of first monotonically increasing and then decreasing, it is determined to be an over-injection condition, and the wetting process is evaluated based on the magnitude and rate of frequency decrease; if the curve of the main resonant frequency f changing with time shows a monotonically decreasing trend after its first appearance, it is determined to be a normal injection condition, and the wetting process is evaluated based on the magnitude and rate of frequency decrease.
[0046] This embodiment Figure 6 As shown, when the frequency of the main resonant frequency f remains unchanged or the rate of change df / dt ≈ 0 or reaches a stable state, the electrolyte wetting is determined to be complete.
[0047] For batteries that had been immersed for 26 hours, the resonant frequency was not yet stable. Upon disassembly, we found a small number of dead zones, indicating that immersion was not complete. Figure 7 As shown. For the battery after 32 hours of immersion, the resonant frequency change rate stabilized. Upon disassembly, we found no dead zones, indicating complete immersion. Figure 8 As shown.
[0048] In summary, this invention provides an unprecedented solution that successfully solves the long-standing problem of monitoring the electrolyte wetting process in the battery manufacturing industry in a low-cost, high-efficiency, and highly reliable manner. The resulting technical effects are a significant improvement in product quality, production efficiency, and intelligence level.
[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.
[0050] Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the invention.
[0051] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A non-destructive testing device for electrolyte wetting state, characterized in that, It includes an acoustic probe module and a coupling module; the acoustic probe module includes an acoustic exciter, an acoustic receiver, and an intelligent signal processing and analysis module; the intelligent signal processing and analysis module is electrically connected to the acoustic exciter and the acoustic receiver.
2. The non-destructive testing device for electrolyte wetting state according to claim 1, characterized in that, The acoustic exciter is a loudspeaker; the acoustic receiver is a microphone.
3. The non-destructive testing device for electrolyte wetting state according to claim 1, characterized in that, The coupling module includes a coupling body for mounting the acoustic exciter and acoustic receiver; the coupling body is provided with a coupling head covering the battery filling hole.
4. The non-destructive testing device for electrolyte wetting state according to claim 3, characterized in that, The inner wall of the coupling body is filled with polyurethane foam sound-absorbing cotton, and a sealing ring is provided on the coupling head; a mechanical arm for applying pressure is provided on the top of the coupling body.
5. A non-destructive testing method for electrolyte wetting state, characterized in that, The damage detection device according to any one of claims 1-4 is used.
6. The non-destructive testing method for electrolyte wetting state according to claim 5, characterized in that, The process includes the following steps: 1) After the battery is injected, it is transferred to the testing station, and the robotic arm drives the acoustic probe module to press down, forming a sealed coupling with the injection port; 2) An excitation signal is applied to collect resonance peak frequency data.
7. The non-destructive testing method for electrolyte wetting state according to claim 6, characterized in that, The specific steps of step 2) are as follows: S1: At the battery's filling port, an acoustic excitation signal containing a specific resonant frequency range is applied using an acoustic exciter, and the acoustic response signal transmitted back through the filling port is synchronously acquired using an acoustic receiver. S2: Use the intelligent signal processing and analysis module to perform frequency domain analysis on the acquired response signal, calculate the system's frequency response function, and identify its main resonant frequency f; S3: Repeat steps S1-S2 to obtain the variation curve of the main resonance frequency f corresponding to different injection times.
8. The non-destructive testing method for electrolyte wetting state according to claim 7, characterized in that, In S3, when the rate of change of the principal resonant frequency f approaches 0, it indicates that the immersion is complete.
9. The non-destructive testing method for electrolyte wetting state according to claim 7, characterized in that, The resonant frequency range in S1 is obtained through the Helmholtz resonator resonant frequency equation; the Helmholtz resonator resonant frequency equation is: Where f is the resonant frequency, C is the speed of sound, A is the cross-sectional area of the injection hole, L is the effective length of the injection hole, and V is the cavity volume; C, A, and L are constants, V is a variable, f ranges from at least fmin to fmax, Vmax = 0.18*X, Vmin = 0.01*X, and X is the cell volume.
10. The non-destructive testing method for electrolyte wetting state according to claim 7, characterized in that, If the curve of the main resonance frequency f changing with time in S3 shows a trend of first monotonically increasing and then decreasing, it is determined to be an over-injection condition. The wetting process is evaluated based on the magnitude and rate of frequency decrease. If the resonant frequency f shows a monotonically decreasing trend after its first appearance in the curve of the main resonant frequency f over time, it is determined to be a routine injection condition, and the wetting process is evaluated based on the magnitude and rate of frequency decrease.