Battery cell detection method, device, system, detection analysis equipment and storage medium

Abstract

The embodiment of the application provides a kind of electric core detection method, device, system, detection analysis equipment and storage medium, it is related to battery technical field.Electric core detection method is applied to detection analysis equipment, comprising: control impedance measuring device to piezoelectric transducer device output first excitation signal, by impedance measuring device receiving piezoelectric transducer device collection second excitation signal;According to second excitation signal, generate the first impedance spectrum of the electric core to be detected;According to the first impedance spectrum, the second impedance spectrum of the qualified electric core corresponding to the electric core to be detected, determine the detection result for the electric core to be detected.The application can utilize piezoelectric impedance principle to detect the electric core shell, can complete the detection of the electric core shell without disassembling battery package, can avoid the damage of battery caused by disassembling battery package, can improve the accuracy and efficiency of the electric core detection, can reduce maintenance cost.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a cell testing method, apparatus, testing and analysis equipment, cell testing system, storage medium, and computer program product. Background Technology

[0002] In electric drive equipment such as new energy vehicles, the battery, as the core energy unit, directly affects the operational safety and reliability of the equipment due to the accuracy and response speed of its safety testing. The battery cells and bottom water-cooling plates in the battery packs of new energy vehicles are generally assembled using structural adhesives. These adhesives have extremely high bonding strength (approximately 10 MPa shear strength), which not only makes cell disassembly difficult but also easily causes irreversible damage to the water-cooling plate and cells during the adhesive removal process. When a battery pack in a new energy vehicle experiences an accident such as a bottom impact, the difficulty in disassembling the cells makes it difficult to quickly and accurately detect damage to the bottom of the cells within the battery pack. To mitigate safety risks, a complete battery pack replacement is usually adopted, increasing repair costs. Summary of the Invention

[0003] In view of the above problems, this application provides a cell testing method, apparatus, testing and analysis equipment, cell testing system, storage medium, and computer program product to improve the accuracy and efficiency of cell testing.

[0004] According to a first aspect of this disclosure, a battery cell testing method is provided, applied to a testing and analysis device, comprising: controlling an impedance measuring device to output a first excitation signal to a piezoelectric transducer, wherein the piezoelectric transducer converts the first excitation signal into mechanical vibration and transmits it to the battery cell to be tested; receiving a second excitation signal collected by the piezoelectric transducer through the impedance measuring device; wherein the piezoelectric transducer converts the mechanical vibration of the battery cell to be tested into an electrical signal to generate the second excitation signal; generating a first impedance spectrum of the battery cell to be tested based on the second excitation signal; and determining the testing result for the battery cell to be tested based on the first impedance spectrum and a second impedance spectrum of a qualified battery cell corresponding to the battery cell to be tested.

[0005] In this embodiment, a first excitation signal is output to the piezoelectric transducer by a control impedance measuring device, causing the cell under test to vibrate. The impedance measuring device receives a second excitation signal generated by the piezoelectric transducer based on the mechanical vibration of the cell under test. Based on the first impedance spectrum generated by the second excitation signal and the second impedance spectrum of a qualified cell corresponding to the cell under test, the test result for the cell under test is determined. By utilizing the piezoelectric impedance principle and employing an excitation output-signal acquisition-impedance spectrum generation-reference comparison test method to test the cell casing, the cell casing can be tested without disassembling the battery pack, avoiding battery damage caused by disassembling the battery pack. This improves the accuracy and efficiency of cell testing, enables the development of appropriate repair plans, and reduces repair costs.

[0006] In some embodiments, determining the test result for the battery cell under test based on the first impedance spectrum and the second impedance spectrum of a qualified battery cell corresponding to the battery cell under test includes: determining the resonance peak difference information of the first impedance spectrum and the second impedance spectrum, wherein the resonance peak difference information includes frequency shift information and / or amplitude change information of the same order resonance peak; and using the resonance peak difference information to determine the test result.

[0007] In this embodiment, the frequency shift information and / or amplitude change information of the same-order resonant peaks of the first and second impedance spectra can accurately reflect the damage status of the battery cell casing under test, thereby improving the accuracy and reliability of the battery cell test results.

[0008] In some embodiments, determining the resonance peak difference information of the first impedance spectrum and the second impedance spectrum includes: determining the resonance peak difference information of each order resonance peak in at least two order resonance peaks based on the first impedance spectrum and the second impedance spectrum.

[0009] In this embodiment, by utilizing the resonance peak difference information of each resonance peak in at least two order resonance peaks, the limitations of using a single order resonance peak for detection can be avoided, thereby improving the accuracy and reliability of the cell detection results.

[0010] In some embodiments, determining the detection result using the resonance peak difference information includes: determining resonance peak reference information corresponding to each of the at least two order resonance peaks, wherein the resonance peak reference information includes: the resonance peak frequency and / or resonance peak amplitude in the second impedance spectrum; and determining the detection result based on the resonance peak difference information of each of the at least two order resonance peaks and the corresponding resonance peak reference information.

[0011] In this embodiment, by combining the reference information and difference information of the resonance peaks of at least two orders to determine the detection result, the deformation of the battery cell casing can be quantified and accurately detected, which can improve the accuracy and reliability of battery cell detection.

[0012] In some embodiments, determining the detection result for the cell under test based on the first impedance spectrum and the second impedance spectrum of a qualified cell corresponding to the cell under test includes: determining a first real part and a first imaginary part of impedance based on the first impedance spectrum; constructing a first complex plane trajectory curve based on the first real part and the first imaginary part of impedance; determining a second real part and a second imaginary part of impedance based on the second impedance spectrum; constructing a second complex plane trajectory curve based on the second real part and the second imaginary part of impedance; and determining the detection result based on the first complex plane trajectory curve and the second complex plane trajectory curve.

[0013] In this embodiment, by constructing a first complex plane trajectory curve and a second complex plane trajectory curve, the real and imaginary parts of the impedance spectrum are combined and transformed into a geometric trajectory, which allows for visualization and multidimensional analysis of impedance information. The complex plane trajectory curve can reflect the coordinated changes of the real and imaginary parts of the cell impedance, and can detect subtle impedance distortions caused by shell damage, thereby improving the sensitivity and accuracy of detecting small deformations of the cell shell.

[0014] In some embodiments, determining the detection result based on the first complex plane trajectory curve and the second complex plane trajectory curve includes: determining multiple geometric feature difference information based on the first complex plane trajectory curve and the second complex plane trajectory curve; determining a deformation sensitivity factor based on the multiple geometric feature difference information; and determining the detection result based on the deformation sensitivity factor.

[0015] In this embodiment, the deformation sensitivity factor is determined by the difference in geometric features, and the difference in the complex plane trajectory curve is transformed into a quantifiable deformation sensitivity factor. This enables the quantification and standardization of the detection results, accurately characterizes the degree of influence of damage on the trajectory, and improves the accuracy and reliability of the detection results.

[0016] In some embodiments, determining the deformation sensitivity factor based on the plurality of geometric feature difference information includes: obtaining the weight coefficient of each geometric feature difference information in the plurality of geometric feature difference information; and calculating a weighted sum based on the plurality of geometric feature difference information and the corresponding weight coefficients, as the deformation sensitivity factor.

[0017] In this embodiment, by using a weighted summation of weighting coefficients to calculate the deformation sensitivity factor, the sensitivity of different geometric features to deformation can be reflected, thereby improving the accuracy and reliability of the detection results.

[0018] In some embodiments, the plurality of geometric feature difference information includes: the difference in trajectory area change rate, centroid coordinate offset distance, and curvature information entropy between the first complex plane trajectory curve and the second complex plane trajectory curve.

[0019] In this embodiment, by determining the differences in features such as the rate of change of the trajectory area, the offset of the center of gravity coordinates, and the difference in curvature information entropy, damage to different dimensions of the battery cell casing can be detected in a coordinated manner, thereby improving the comprehensiveness and accuracy of the detection.

[0020] In some embodiments, the control impedance measuring device outputs the first excitation signal to the piezoelectric transducer, wherein the piezoelectric transducer converts the first excitation signal into mechanical vibration and transmits it to the qualified battery cell; the impedance measuring device receives the third excitation signal collected by the piezoelectric transducer; wherein the piezoelectric transducer converts the mechanical vibration of the qualified battery cell into an electrical signal to generate the third excitation signal; and the second impedance spectrum is generated based on the third excitation signal.

[0021] In this embodiment, a first excitation signal is output to the piezoelectric transducer by controlling the impedance measuring device to cause the qualified battery cell to vibrate. The impedance measuring device receives a third excitation signal generated by the piezoelectric transducer based on the mechanical vibration of the qualified battery cell, and a second impedance spectrum is generated based on the third excitation signal. This allows the acquisition conditions of the reference impedance spectrum to be consistent with those of the battery cell under test, reducing detection errors caused by deviations in the reference impedance spectrum, improving the effectiveness of the reference impedance spectrum, and thus improving the accuracy of battery cell testing.

[0022] In some embodiments, the piezoelectric transducer is positioned on a busbar on top of the cell under test or the qualified cell.

[0023] In this embodiment, by placing the piezoelectric transducer on the top busbar of the battery cell, it is convenient to install the piezoelectric transducer without disassembling the battery pack, and it can effectively transmit the mechanical vibration of the battery cell, with high vibration transmission efficiency and reduced detection error.

[0024] In some embodiments, the piezoelectric transducer includes a first piezoelectric element and a second piezoelectric element; the first piezoelectric element is used to output the first excitation signal; and the second piezoelectric element is used to acquire the second excitation signal.

[0025] In this embodiment, by having the piezoelectric transducer have a dual-piece separation structure of a first piezoelectric piece and a second piezoelectric piece, signal interference caused by a single piezoelectric piece both exciting and acquiring signals can be avoided, thereby improving the signal-to-noise ratio and accuracy of the acquired signal. Separating the excitation and acquisition functions allows for the optimization of the parameters of the first and second piezoelectric pieces, thereby improving the stability of the excitation signal and the accuracy of the acquired signal.

[0026] In some embodiments, the detection result includes whether the casing of the battery cell under test is damaged and damage information.

[0027] In some embodiments, according to a second aspect of this disclosure, a battery cell casing testing device is provided, applied to a testing and analysis equipment, comprising: an excitation control module for controlling an impedance measuring device to output a first excitation signal to a piezoelectric transducer, wherein the piezoelectric transducer converts the first excitation signal into mechanical vibration and transmits it to the battery cell under test; a signal receiving module for receiving a second excitation signal collected by the piezoelectric transducer through the impedance measuring device; wherein the piezoelectric transducer converts the mechanical vibration of the battery cell under test into an electrical signal to generate the second excitation signal; an impedance spectrum generation module for generating a first impedance spectrum of the battery cell under test based on the second excitation signal; and a detection processing module for determining the detection result for the battery cell under test based on the first impedance spectrum and a second impedance spectrum of a qualified battery cell corresponding to the battery cell under test.

[0028] In this embodiment, a first excitation signal is output to the piezoelectric transducer by a control impedance measuring device, causing the cell under test to vibrate. The impedance measuring device receives a second excitation signal generated by the piezoelectric transducer based on the mechanical vibration of the cell under test. Based on the first impedance spectrum generated by the second excitation signal and the second impedance spectrum of a qualified cell corresponding to the cell under test, the test result for the cell under test is determined. By utilizing the piezoelectric impedance principle and employing an excitation output-signal acquisition-impedance spectrum generation-reference comparison test method to test the cell casing, the cell casing can be tested without disassembling the battery pack, avoiding battery damage caused by disassembling the battery pack. This improves the accuracy and efficiency of cell testing, enables the development of appropriate repair plans, and reduces repair costs.

[0029] In some embodiments, according to a third aspect of this disclosure, a battery cell casing testing apparatus is provided for use in a testing and analysis device, comprising: a memory; and a processor coupled to the memory, the processor being configured to perform the method described above based on instructions stored in the memory.

[0030] In some embodiments, according to a fourth aspect of this disclosure, a testing and analysis apparatus is provided, including the battery cell casing testing device as described above.

[0031] In some embodiments, according to a fifth aspect of this disclosure, a detection system is provided, comprising: an impedance measuring device, a piezoelectric transducer, and a detection and analysis device as described above.

[0032] In some embodiments, according to a sixth aspect of this disclosure, a computer-readable storage medium is provided that stores computer instructions which are executed by a processor using the method described above.

[0033] In some embodiments, according to a seventh aspect of this disclosure, a computer program product is provided, the computer program product storing computer instructions which are executed by a processor using the method described above.

[0034] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0036] Figure 1 This is a schematic flowchart of some embodiments of the battery cell testing method disclosed herein;

[0037] Figure 2A This is a schematic diagram showing the installation of battery cells within a battery pack.

[0038] Figure 2B This is a schematic diagram illustrating the testing of battery cells within a battery pack.

[0039] Figure 3 This is a schematic diagram illustrating the process of determining the test result for the battery cell to be tested in some embodiments of the battery cell testing method disclosed herein;

[0040] Figure 4 This is a schematic diagram showing the relationship between impedance amplitude and frequency;

[0041] Figure 5 This is a schematic diagram illustrating the relationship between phase value and frequency;

[0042] Figure 6 A schematic diagram showing the offset of the resonant frequency of each order resonance peak;

[0043] Figure 7 A schematic diagram showing the variation of peak height for each order of resonance peak;

[0044] Figure 8 This is a flowchart illustrating the determination of the test result for the battery cell to be tested in some other embodiments of the battery cell testing method disclosed herein;

[0045] Figure 9 This is a flowchart illustrating the determination of detection results based on a complex plane trajectory curve in some other embodiments of the cell testing method disclosed herein;

[0046] Figure 10 This is a flowchart illustrating the determination of deformation sensitivity factors in some other embodiments of the battery cell testing method disclosed herein;

[0047] Figure 11 This is a schematic diagram of the impedance spectrum as a function of frequency in the complex plane.

[0048] Figure 12 A schematic diagram of the comprehensive deformation indication obtained based on the deformation sensitivity factor;

[0049] Figure 13 The diagram shows some embodiments of the battery cell testing device disclosed herein.

[0050] Figure 14 This is a schematic diagram of the detection and processing module in some embodiments of the battery aging prediction device of this disclosure;

[0051] Figure 15 The following are schematic diagrams of modules for some other embodiments of the battery cell testing device disclosed herein;

[0052] Figure 16 This is a schematic diagram of some embodiments of the detection system disclosed herein. Detailed Implementation

[0053] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0055] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0056] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least some of the embodiments of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0057] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0058] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0059] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0060] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0061] Figure 1 This is a flowchart illustrating some embodiments of the battery cell testing method disclosed herein, such as... Figure 1 As shown, the cell testing method is applied to the testing and analysis equipment, including steps S101 to S104:

[0062] Step S101: The control impedance measuring device outputs a first excitation signal to the piezoelectric transducer, wherein the piezoelectric transducer converts the first excitation signal into mechanical vibration and transmits it to the cell under test.

[0063] The battery cells to be tested can include individual cells or cell groups, and the cells can be various types, such as rigid-cased cells. The cells can be installed in battery packs, which can be various types, such as automotive CTP (Cell-to-Pack) battery packs. The testing and analysis equipment can be various devices, such as PCs or other host computers; impedance measurement equipment includes impedance analyzers; and piezoelectric transducers can be various devices that utilize the electromechanical coupling characteristics of piezoelectric materials to achieve the mutual conversion of mechanical energy and electrical energy.

[0064] The testing and analysis equipment controls the impedance analyzer to output a first excitation signal. This first excitation signal can be of various types, such as an AC sweep frequency signal with a preset frequency range (e.g., 10-1000kHz), a signal amplitude ≤5mV, and a sweep step size set in 5kHz intervals. This signal drives the piezoelectric transducer to vibrate. The piezoelectric transducer, through the inverse piezoelectric effect, converts the first excitation signal output by the impedance measurement equipment into mechanical vibration and transmits this vibration to the battery cell under test, causing the cell to vibrate.

[0065] Step S102: Receive the second excitation signal collected by the piezoelectric transducer through the impedance measurement device; wherein, the piezoelectric transducer converts the mechanical vibration of the cell under test into an electrical signal to generate the second excitation signal.

[0066] The piezoelectric transducer can convert the mechanical vibration of the battery cell under test into an electrical signal through the positive piezoelectric effect, generate a second excitation signal and transmit it to the impedance measurement device; the impedance measurement device then transmits the second excitation signal to the detection and analysis device.

[0067] Step S103: Generate the first impedance spectrum of the cell to be tested based on the second excitation signal.

[0068] The first impedance spectrum of the detection cell generated based on the second excitation signal is a spectrum that can reflect the correlation between frequency and impedance characteristics. The first impedance spectrum contains information such as the real part, imaginary part, amplitude, and phase of the impedance.

[0069] Step S104: Determine the test result for the cell under test based on the first impedance spectrum and the second impedance spectrum of the qualified cell corresponding to the cell under test.

[0070] The qualified battery cell corresponding to the cell under test can be a cell of the same model as the cell under test that is undamaged. The cell under test and the qualified cell can be installed in a battery pack of the same model. The second impedance spectrum is a spectrum that reflects the correlation between frequency and impedance characteristics. The second impedance spectrum includes information such as the real part, imaginary part, amplitude, and phase of the impedance. The qualified cell can be tested beforehand to obtain and store the second impedance spectrum; alternatively, the qualified cell can be tested during the testing of the cell under test to obtain the second impedance spectrum.

[0071] If bulges, dents, or other deformations occur on the sides or bottom of the battery cell under test, it will cause changes in the local stiffness and damping of the battery cell's casing, thus altering its vibration characteristics. The second impedance spectrum of a qualified battery cell can be used as a reference impedance spectrum. Based on the second impedance spectrum of a qualified battery cell and the first impedance spectrum of the battery cell under test, the test results can be determined. The test results include: whether the battery cell's casing is damaged and damage information; damage includes bulges, dents, and other deformations; damage information includes the type and degree of deformation; deformation types include bulges and dents, and the degree of deformation includes the size and extent of bulges and dents. Based on the test results, corresponding repair plans can be formulated, including repairing the damaged battery cell or replacing the battery cell, which can be determined according to the specific repair strategy.

[0072] The disclosed cell testing method involves controlling an impedance measuring device to output a first excitation signal to a piezoelectric transducer, causing the cell under test to vibrate. The impedance measuring device then receives a second excitation signal generated by the piezoelectric transducer based on the mechanical vibration of the cell under test. The test result for the cell under test is determined based on a first impedance spectrum generated by the second excitation signal and a second impedance spectrum of a qualified cell corresponding to the cell under test. By utilizing the piezoelectric impedance principle and employing an excitation output-signal acquisition-impedance spectrum generation-reference comparison testing method, the cell casing can be tested without disassembling the battery pack. This avoids battery damage caused by disassembling the battery pack, improves the accuracy and efficiency of cell testing, and allows for the development of appropriate repair plans for cells with casing deformation or other damage, thereby reducing repair costs.

[0073] The second impedance spectrum can be obtained using various methods. For example, the detection and analysis equipment controls the impedance measuring device to output a first excitation signal to the piezoelectric transducer, which converts the first excitation signal into mechanical vibration and transmits it to the qualified battery cell; the impedance measuring device receives the third excitation signal collected by the piezoelectric transducer; the piezoelectric transducer converts the mechanical vibration generated by the qualified battery cell under the action of the third excitation signal into an electrical signal, generating the third excitation signal; the detection and analysis equipment generates the second impedance spectrum based on the third excitation signal.

[0074] By controlling the impedance measurement device to output a first excitation signal to the piezoelectric transducer, the qualified battery cell vibrates. The impedance measurement device receives the third excitation signal generated by the piezoelectric transducer based on the mechanical vibration of the qualified battery cell, and generates a second impedance spectrum based on the third excitation signal. This allows the acquisition conditions of the reference impedance spectrum to be consistent with those of the battery cell under test, reducing the detection error caused by the deviation of the reference impedance spectrum, improving the effectiveness of the reference impedance spectrum, and thus improving the accuracy of battery cell testing.

[0075] During testing, the piezoelectric transducer can be installed in multiple locations. For example, it can be placed on the busbar at the top of the cell under test or a qualified cell, or on the casing of the cell under test. Installing the piezoelectric transducer on the busbar at the top of the cell facilitates installation without disassembling the battery pack and effectively transmits mechanical vibrations from the cell, resulting in high vibration transmission efficiency and reduced testing errors.

[0076] Piezoelectric transducers can be of various types. For example, a piezoelectric transducer includes a first piezoelectric element and a second piezoelectric element. The first piezoelectric element is used to output a first excitation signal, and the second piezoelectric element is used to acquire a second or third excitation signal. The first and second piezoelectric elements can be of various types, such as lead zirconate titanate (PZT) piezoelectric ceramic wafers.

[0077] By equipping the piezoelectric transducer with a dual-piece structure consisting of a first piezoelectric element (excitation) and a second piezoelectric element (acquisition), signal interference caused by a single piezoelectric element performing both excitation and acquisition can be avoided. This improves the signal-to-noise ratio and accuracy of the acquired signal. Separating the excitation and acquisition functions allows for the optimization of the parameters of the first and second piezoelectric elements, thereby enhancing the stability of the excitation signal and the accuracy of the acquired signal.

[0078] In some embodiments, the battery pack is an automotive CTP battery pack, which is composed of a large number of battery cells arranged and combined. For example... Figure 2A As shown, the positive and negative terminals at the top of the battery cells are connected in series via busbars, and the bottom of the battery cells is bonded with a water-cooling plate using structural adhesive, forming a double-layer structure of adhesive layer and water-cooling plate.

[0079] When the bottom of a CTP battery pack in a vehicle is bumped or knocked, and inspection is required, open the top cover of the CTP battery pack and remove the relevant insulating components to expose the busbars at the top of the cells; for example... Figure 2B As shown, within the automotive CTP battery pack, the normal area and the impact area at the bottom of the battery pack are identified; on the busbar of the positive or negative terminal of the cell to be tested in the impact area, as shown... Figure 2B At point A or B, apply sensor coupling agent and install a piezoelectric transducer. The function of the sensor coupling agent is to eliminate the air gap between the piezoelectric transducer and the busbar, so that the vibration signal of the cell under test can be efficiently transmitted between the piezoelectric transducer and the busbar.

[0080] The detection and analysis equipment is connected to the impedance measurement equipment, which in turn is connected to the piezoelectric transducer. The impedance measurement equipment receives commands from the detection and analysis equipment and sends an excitation signal with a corresponding modulated waveform at its output slot. The output interface is connected to the piezoelectric transducer. The impedance measurement equipment serves as the excitation source for driving the vibration of the piezoelectric transducer and receives the excitation signal from the piezoelectric transducer. The piezoelectric transducer and the device under test are coupled together to form a new resonant frequency.

[0081] The detection and analysis equipment controls the impedance measurement equipment to output a first excitation signal to the piezoelectric transducer installed at point A or B, and receives the second excitation signal collected by the piezoelectric transducer installed at point A or B through the impedance measurement equipment, and generates a first impedance spectrum based on the second excitation signal.

[0082] On the busbar of the positive or negative terminal of the battery cell under test in the normal area, such as Figure 2B At point C or D, apply sensor coupling agent and install a piezoelectric transducer. The detection and analysis equipment controls the impedance measurement equipment to output a first excitation signal to the piezoelectric transducer installed at point C or D. The impedance measurement equipment receives a third excitation signal collected by the piezoelectric transducer installed at point C or D, and generates a second impedance spectrum based on the third excitation signal.

[0083] Based on the impact range at the bottom of the battery pack, each cell within that range is tested individually. Within the impact range at the bottom of the battery pack, one or more qualified cells can be selected to obtain the second impedance spectrum of these one or more qualified cells, which serves as the reference impedance spectrum. After obtaining multiple second impedance spectra corresponding to multiple qualified cells, the average of the multiple second impedance spectra can be calculated to obtain the average impedance spectrum, which is then used as the reference impedance spectrum.

[0084] By utilizing the positive / inverse piezoelectric effect of the piezoelectric transducer, the change in the mechanical impedance of the battery cell under test is reflected as a change in the measured electrical impedance. When the battery cell under test is damaged, the local stiffness / damping of the casing will change, and the mechanical impedance will change. This is manifested as a frequency shift and amplitude change of the resonance peak of the impedance spectrum, which can realize the detection of the battery cell casing.

[0085] Figure 3 The following is a schematic flowchart illustrating the process of determining the test result for the battery cell under test in some embodiments of the battery cell testing method disclosed herein, such as... Figure 3 As shown:

[0086] Step S301: Determine the resonance peak difference information of the first impedance spectrum and the second impedance spectrum, wherein the resonance peak difference information includes the frequency shift information and / or amplitude change information of the same order resonance peak;

[0087] The resonance peaks of the first and second impedance spectra refer to the extreme impedance characteristic peaks exhibited by the battery cell at specific frequencies. The first and second impedance spectra can have multiple resonance peaks, which refer to multiple resonance peaks appearing in the battery cell at different frequency ranges. Each resonance peak corresponds to a specific vibration mode of the battery cell casing. Multiple resonance peaks appear sequentially from low to high frequencies of the excitation signal. Determining the difference in resonance peaks between the first and second impedance spectra can provide information on the frequency shift and / or amplitude variation of one or more resonance peaks of the same order in both the first and second impedance spectra.

[0088] Step S302: Determine the detection result using the resonance peak difference information.

[0089] By using the frequency shift information and / or amplitude variation information of the same-order resonant peaks of the first and second impedance spectra, the damage status of the battery cell casing under test can be accurately reflected, thus improving the accuracy and reliability of the battery cell casing test results.

[0090] Several methods can be used to determine the detection result by utilizing the resonance peak difference information. For example, if the resonance peak difference information is less than the corresponding threshold, it is determined that the casing of the battery cell under test has not undergone deformation or other damage. If the resonance peak difference information is greater than the corresponding threshold, it is determined that the casing of the battery cell under test has undergone deformation or other damage.

[0091] Through experiments, a quantitative relationship between resonance peak difference information and damage information can be established. Damage information includes deformation type and degree of deformation. Deformation type includes bulges and pits, and degree of deformation includes the size and location of bulges and pits. Based on the resonance peak difference information and using the quantitative relationship of damage, the deformation type and degree of deformation can be determined.

[0092] In some embodiments, the resonance peak difference information of each resonance peak in at least two order resonance peaks can be determined based on the first impedance spectrum and the second impedance spectrum. Utilizing the resonance peak difference information of each resonance peak in at least two order resonance peaks avoids the limitations of using a single order resonance peak for detection, thus improving the accuracy and reliability of cell detection results.

[0093] There are several methods to determine the detection result using resonance peak difference information. For example, the resonance peak reference information corresponding to each of the at least two order resonance peaks can be determined, including the resonance peak frequency and / or resonance peak amplitude in the second impedance spectrum; the detection result can be determined based on the resonance peak difference information of each of the at least two order resonance peaks and the corresponding resonance peak reference information.

[0094] By combining the reference information and difference information of the resonance peaks of at least two orders to determine the detection results, the deformation of the battery cell casing can be quantified and accurately detected, which can improve the accuracy and reliability of battery cell detection.

[0095] The detection and analysis equipment can set a scanning frequency range, which can be 10-1000kHz. Based on the scanning frequency range, the detection and analysis equipment controls the impedance measurement equipment to output the first excitation signal to the piezoelectric transducer. When the detection and analysis equipment completes the acquisition of one frequency, it starts the excitation of the next frequency. After the frequency sweep is completed, the first impedance spectrum of the cell under test is generated according to the second excitation signal.

[0096] In some embodiments, the busbar located on top of the cell under test or the qualified cell is used as the carrier of the piezoelectric transducer. Without occupying additional space or damaging the battery pack structure, the mechanical vibration of the cell is induced by frequency sweep excitation (30-400kHz). The deformation of the pits at the bottom of the cell and other locations causes local stiffness changes, which are converted into quantifiable resonant peak shifts.

[0097] Information about the Nth-order (N≥1) resonance peaks can be extracted from the impedance spectrum. The following explanation uses three-order resonance peaks as an example. For instance, based on the first impedance spectrum, the frequency values ​​(f1, f2, f3) and amplitudes (A1, A2, A3) of the first Nth-order (N=3) resonance peaks can be extracted. Based on the second impedance spectrum, the frequency values ​​(f1_ref, f2_ref, f3_ref) and amplitudes (A1_ref, A2_ref, A3_ref) of the Nth-order (N=3) resonance peaks can be extracted.

[0098] Calculate the resonance peak difference information between the first and second impedance spectra. This resonance peak difference information includes frequency shift information and / or amplitude variation information for resonance peaks of the same order. For example, the frequency shift information for resonance peaks of the same order is (f1-f1_ref, f2-f2_ref, f3-f3_ref), and the amplitude variation information is (A1-A1_ref, A2-f2_ref, A3-A3_ref). The reference information for each resonance peak among the three orders is (f1_ref, f2_ref, f3_ref) and / or (A1_ref, A2_ref, A3_ref).

[0099] Various methods can be used to determine the detection results of the battery cell casing based on the frequency shift information and / or amplitude change information of the same-order resonant peak. For example, based on experimental results, a first quantitative relationship of damage between the frequency shift information of the same-order resonant peak and the deformation type and degree of the battery cell casing can be established; a second quantitative relationship of damage between the amplitude change information of the same-order resonant peak and the deformation type and degree of the battery cell casing can be established; and a third quantitative relationship of damage between the frequency shift information and amplitude change information of the same-order resonant peak and the deformation type and degree of the battery cell casing can be established.

[0100] The detection results can be determined based on one or more of the first, second, and third quantitative damage relationships, as well as the corresponding frequency offset information and / or amplitude change information. The detection results include whether the cell casing is damaged or deformed, and the type and degree of deformation of the cell casing.

[0101] Multiple methods can be used to determine the detection results based on the resonance peak reference information and / or resonance peak reference information corresponding to each order resonance peak in the first three resonance peaks. For example, the resonant peak reference information includes (f1_ref, f2_ref, f3_ref) and / or the resonant peak amplitude (A1_ref, A2_ref, A3_ref). The resonant characteristic vector is constructed by using the information of the first three resonant peaks. The resonant characteristic vector is V1 = [∆f1 / f1_ref, ∆f2 / f2_ref, ∆f3 / f3_ref], V2 = [∆A1 / A1_ref, ∆A2 / A2_ref, ∆A3 / A3_ref], and V3 = V1 + V2. Wherein, ∆f1 = f1 - f1_ref, ∆f2 = f2 - f2_ref, ∆f3 = f3 - f3_ref; ∆A1 = A1 - A1_ref, ∆A2 = A2 - A2_ref, ∆A3 = A3 - A3_ref.

[0102] Based on the experimental results, a first quantitative relationship of damage, such as the deformation type and degree of deformation of V1 and the battery cell casing, a second quantitative relationship of damage, such as the deformation type and degree of deformation of V2 and the battery cell casing, and a third quantitative relationship of damage, such as the deformation type and degree of deformation of V3 and the battery cell casing, can be established. The detection results can be determined based on one or more of the first, second, and third quantitative relationships of damage and one or more of the corresponding V1, V2, and V3.

[0103] Deformation of the battery cell casing leads to changes in the stiffness and mass distribution of the casing, and these changes have different effects on different order resonant modes. For example, the impact of local bulging on higher-order modes (corresponding to local vibration) is usually much greater than its impact on lower-order modes (corresponding to overall vibration). By analyzing the change patterns of the resonant eigenvectors (e.g., which resonant peak has the most frequency shift information, the most significant amplitude change, etc.), the type of deformation (such as uniform expansion or local bulging, etc.) can be distinguished.

[0104] By extracting information from at least two different order resonance peaks in the piezoresistive impedance spectrum and using the multi-resonance peak analysis method, the influence of temperature changes and other factors causing uniformity drift in the resonance frequency can be avoided. This effectively decouples deformation from temperature interference, improving the accuracy and consistency of cell testing.

[0105] In some embodiments, the battery cells within the battery pack of a new energy vehicle are tested. Figure 4 The impedance amplitude versus frequency graph generated based on the impedance spectrum is shown in Figure 41, which is the impedance amplitude versus frequency graph of a qualified battery cell, Figure 42, which is the impedance amplitude versus frequency graph of the first battery cell to be tested, and Figure 43, which is the impedance amplitude versus frequency graph of the second battery cell to be tested.

[0106] Curves 41, 42, and 43 have three resonance peaks, each corresponding to a different resonant frequency. Based on curves 41, 42, and 43, the frequency shift and / or amplitude variation information of the third-order resonance peaks between the first cell under test and the qualified cell, and the frequency shift and / or amplitude variation information of the third-order resonance peaks between the second cell under test and the qualified cell can be determined. Based on the frequency shift and / or amplitude variation information, and the pre-set quantitative damage relationship, it can be determined that the outer shells of the first and second cells under test have undergone deformation, namely uniform expansion and local bulging, respectively.

[0107] Figure 5 The graphs show the relationship between phase value and frequency. Curve 51 represents the relationship between phase value and frequency for a qualified battery cell, curve 52 represents the relationship between phase value and frequency for the first battery cell under test, and curve 53 represents the relationship between phase value and frequency for the second battery cell under test. Figure 5As shown, the reliability of the detection results can be verified by the relationship curve between phase value and frequency. At each resonance peak and at each resonance frequency, the phase jumps by 180 degrees, which verifies the accuracy of the detection results.

[0108] Figure 6 This diagram shows the relationship between the resonant peak order and frequency shift, where frequency shift represents the deviation between the resonant peak frequency of the cell under test and that of a qualified cell. During uniform expansion, all three resonant peak frequencies shift to lower frequencies, but the magnitude of the shift is similar. When localized bulging occurs, the shift in the resonant peak frequency of the higher-order peak (3rd order) is the largest, while the shift in the resonant peak frequency of the lower-order peak (1st order) is the smallest. Based on the shift characteristics of the multi-order resonant peak frequencies, a quantitative damage relationship can be constructed, and the deformation type can be distinguished according to this relationship.

[0109] Figure 7 This graph shows the relationship between the resonant peak order and amplitude variation, where amplitude variation represents the deviation between the resonant peak amplitude of the cell under test and that of a qualified cell. In this graph, the vertical axis values ​​are all in the negative plane, indicating that deformation increases mechanical energy dissipation, thus reducing the resonant peak amplitude. Different deformation types have different effects on the amplitude of different resonant peak orders. A quantitative damage relationship can be constructed based on the variation characteristics of multi-order resonant peak amplitudes, and this relationship can be used to distinguish deformation types. Since amplitude variation is more sensitive to certain types of damage, resonant peak amplitude variation can be used as a supplement to frequency shift for deformation type determination.

[0110] Figure 8 The following are schematic flowcharts illustrating the determination of the test result for the battery cell under test in some other embodiments of the battery cell testing method of this disclosure, such as... Figure 8 As shown:

[0111] Step S801: Determine the real part and imaginary part of the first impedance based on the first impedance spectrum.

[0112] The first impedance spectrum contains information such as the real part of the impedance, the imaginary part of the impedance, the impedance amplitude, and the phase. The real part of the first impedance is the energy loss portion of the impedance in the first impedance spectrum. When the cell casing deforms, the mechanical damping increases, and the value of the real part of the first impedance changes accordingly. The change pattern reflects the difference in energy dissipation caused by the deformation. The imaginary part of the first impedance is the energy storage portion of the impedance in the first impedance spectrum. Deformation of the cell casing changes the stiffness and mass distribution of the casing, thereby affecting the energy storage capacity of the system and causing the value of the imaginary part of the first impedance to shift.

[0113] Step S802: Construct the first complex plane trajectory curve based on the real part and the imaginary part of the first impedance.

[0114] The first complex plane trajectory curve is a curve with the real part of the first impedance as the abscissa and the imaginary part of the first impedance as the ordinate. The first complex plane trajectory curve can be a Nyquist plot, etc. By analyzing the geometric characteristics of this trajectory, the impedance difference between the cell under test and the qualified cell can be accurately quantified, thereby determining the type and degree of casing deformation, etc.

[0115] Step S803: Determine the real part of the second impedance and the imaginary part of the second impedance based on the second impedance spectrum.

[0116] The second impedance spectrum contains information such as the real part of the impedance, the imaginary part of the impedance, the impedance amplitude, and the phase. The real part of the second impedance is the reference part for energy loss of the impedance in the second impedance spectrum, and the imaginary part of the second impedance is the reference part for energy storage of the impedance in the second impedance spectrum.

[0117] Step S804: Construct the second complex plane trajectory curve based on the real part of the second impedance and the imaginary part of the second impedance.

[0118] The second complex plane trajectory curve is a curve with the real part of the second impedance as the abscissa and the imaginary part of the second impedance as the ordinate. The second complex plane trajectory curve can be a Nyquist plot, etc.

[0119] Step S805: Determine the detection result based on the first complex plane trajectory curve and the second complex plane trajectory curve.

[0120] By constructing the first complex plane trajectory curve and the second complex plane trajectory curve, the real and imaginary parts of the impedance spectrum are combined and transformed into a geometric trajectory. This allows for visualization and multidimensional analysis of impedance information. The complex plane trajectory curve can reflect the coordinated changes of the real part (resistance characteristics) and the imaginary part (reactance characteristics) of the cell impedance. It can detect subtle impedance distortions caused by shell damage (e.g., local damage may cause "burrs" or arc deformation in the trajectory), improving the sensitivity and accuracy of detecting small deformations of the cell shell.

[0121] Multiple methods can be used to determine the detection results based on the first complex plane trajectory curve and the second complex plane trajectory curve. Figure 9 This is a flowchart illustrating the determination of detection results based on the complex plane trajectory curve in some other embodiments of the cell testing method disclosed herein, such as... Figure 9 As shown:

[0122] Step S901: Determine multiple geometric feature difference information based on the first complex plane trajectory curve and the second complex plane trajectory curve.

[0123] Step S902: Determine the deformation sensitivity factor based on the differences in multiple geometric features.

[0124] Step S903: Determine the detection result based on the deformation sensitivity factor.

[0125] By identifying deformation-sensitive factors through differences in geometric features, the differences in complex plane trajectory curves can be transformed into quantifiable deformation-sensitive factors. This enables the quantification and standardization of detection results, accurately characterizes the degree of damage's impact on the trajectory, and improves the accuracy and reliability of the detection results.

[0126] Various methods can be used to determine the detection results using deformation sensitivity factors. For example, if the deformation sensitivity factor is less than the corresponding threshold, it is determined that the battery cell's casing has not suffered deformation or other damage. If the deformation sensitivity factor is greater than the corresponding threshold, it is determined that the battery cell's casing has suffered deformation or other damage. Experiments can be used to establish a quantitative relationship between the value of the deformation sensitivity factor and damage information, including deformation type and degree. Deformation type includes bulges and dents, while degree includes the size and location of bulges and dents. Based on the deformation sensitivity factor and using the quantitative relationship, the deformation type and degree can be determined.

[0127] Figure 10 This is a flowchart illustrating the determination of deformation sensitivity factors in some other embodiments of the cell testing method disclosed herein, such as... Figure 10 As shown:

[0128] Step S1001: Obtain the weight coefficients of each geometric feature difference information in multiple geometric feature difference information.

[0129] The sum of the weighting coefficients for all geometric feature differences is 1. For example, the weighting coefficient for the trajectory area change rate is 0.3, the weighting coefficient for the centroid coordinate offset distance is 0.2, and the weighting coefficient for the difference in curvature entropy is 0.5.

[0130] Step S1002: Calculate a weighted sum based on the differences in multiple geometric features and the corresponding weight coefficients, which serves as the deformation sensitivity factor.

[0131] By calculating the deformation sensitivity factor using a weighted summation of weighted coefficients, the sensitivity of different geometric features to deformation can be reflected, thus improving the accuracy and reliability of the detection results.

[0132] Geometric feature difference information can be of various types. For example, multiple geometric feature difference information includes the rate of change of trajectory area between the first complex plane trajectory curve and the second complex plane trajectory curve, the centroid coordinate offset distance, and the difference in curvature information entropy, etc.

[0133] The rate of change of the trajectory area can reflect the overall size change of the trajectory (for example, damage to the casing may cause an overall change in impedance, thus changing the trajectory area), the centroid coordinate offset can reflect the overall positional offset of the trajectory (for example, overall deformation may cause the centroid to move), and the difference in curvature entropy can reflect the disorder of the local shape of the trajectory (for example, local damage makes the trajectory "rough," increasing the entropy value). By determining the differences in features such as the rate of change of the trajectory area, the centroid coordinate offset, and the difference in curvature entropy, damage in different dimensions of the battery cell casing can be detected collaboratively, improving the comprehensiveness and accuracy of the detection.

[0134] In some embodiments, the impedance spectrum may include information such as the real part (R) and imaginary part (X) of the impedance. By calculating the geometric characteristic parameters of the trajectory formed by the real part (R) and imaginary part (X) of the impedance on the complex plane as the frequency changes, and comparing the difference between the geometric characteristic parameters and their reference values, it can be determined whether the cell casing has been damaged.

[0135] For example, for a qualified battery cell, the second complex plane trajectory curve will form a smooth "arc" in the resonance region. When the battery cell casing deforms, the geometry of this arc will be distorted. Multiple geometric feature differences include the rate of change of trajectory area between the first and second complex plane trajectory curves, the centroid coordinate offset distance, and the difference in curvature information entropy.

[0136] The formula for calculating the area of ​​a complex plane trajectory curve is:

[0137] (1-1);

[0138] Where A is the area of ​​the complex plane trajectory curve, N is the number of sampling points on the complex plane trajectory curve, Ri is the real part of the impedance at the i-th sampling point, representing the energy loss characteristic; Xi is the imaginary part of the impedance at the i-th sampling point, representing the energy storage characteristic. Ri+1 is the real part of the impedance at the (i+1)-th sampling point; Xi+1 is the imaginary part of the impedance at the (i+1)-th sampling point.

[0139] According to formula (1-1), the area of ​​the trajectory curve in the first complex plane can be calculated as A. current The area A of the second complex plane trajectory curve reference The trajectory area reflects the energy dissipation characteristics, and the deformation of the cell casing leads to changes in mechanical damping.

[0140] Calculate the rate of change of the trajectory area between the first complex plane trajectory curve and the second complex plane trajectory curve:

[0141] (1-2);

[0142] The formula for calculating the abscissa of the centroid of the complex plane trajectory curve is:

[0143] (1-3);

[0144] Where Gx is the centroid abscissa of the complex plane trajectory curve, reflecting the center position of the impedance trajectory in the real axis direction; N is the number of sampling points on the complex plane trajectory curve; Ri is the real part of the impedance at the i-th sampling point (in ohms Ω), reflecting the energy loss characteristics of the cell under test at the corresponding frequency.

[0145] The formula for calculating the ordinate of the centroid of the complex plane trajectory curve is:

[0146] (1-4);

[0147] Where Gx is the centroid ordinate of the complex plane trajectory curve, reflecting the center position of the impedance trajectory in the imaginary axis direction; N is the number of sampling points on the complex plane trajectory curve; Ni is the imaginary part of the impedance at the i-th sampling point (in ohms Ω), reflecting the energy storage characteristics of the cell under test at the corresponding frequency.

[0148] Formula (1-3) calculates the centroid position of the complex plane trajectory curve along the real axis by taking the arithmetic mean of the real parts of the impedance at all sampling points on the complex plane. When the cell casing deforms, the geometric characteristics of the complex plane trajectory curve change, and the abscissa Gx of the centroid shifts accordingly. Formula (1-4) calculates the centroid position of the impedance trajectory along the imaginary axis by taking the arithmetic mean of the imaginary parts of the impedance at all sampling points on the complex plane. The centroid position of the complex plane trajectory curve reflects the overall change in impedance distribution and is sensitive to changes in overall stiffness.

[0149] Based on formula (1-3), the centroid abscissa Gx of the first complex plane trajectory curve and the centroid abscissa Gx0 of the second complex plane trajectory curve can be calculated. Based on formula (1-4), the centroid ordinate Gy of the first complex plane trajectory curve and the centroid ordinate Gy0 of the second complex plane trajectory curve can be calculated.

[0150] The centroid coordinate offset distance between the first complex plane trajectory curve and the second complex plane trajectory curve is calculated as follows:

[0151] (1-5);

[0152] For a point on the complex plane trajectory curve The formula for calculating curvature is:

[0153] (1-6);

[0154] Where Ki is the curvature at the i-th sampling point in the complex plane trajectory curve; Ri′ is the first derivative of the real part of the impedance at the i-th sampling point; Xi′ is the first derivative of the imaginary part of the impedance at the i-th sampling point; Ri′′ is the second derivative of the real part of the impedance at the i-th sampling point; and Xi′′ is the second derivative of the imaginary part of the impedance at the i-th sampling point.

[0155] The derivative in formula (1-6) can be calculated using the central difference method:

[0156] (1-7);

[0157] Where Ri+1 is the real part of the impedance at the (i+1)th sampling point, in Ω; Ri−1 is the real part of the impedance at the (i−1)th sampling point; and Δf is the frequency interval between adjacent sampling points.

[0158] (1-8);

[0159] Where Xi+1 is the imaginary part of the impedance at the (i+1)th sampling point, in Ω; and Xi−1 is the imaginary part of the impedance at the (i−1)th sampling point.

[0160] (1-9);

[0161] Where Ri is the real part of the impedance at the i-th sampling point.

[0162] (1-10);

[0163] Where Xi is the imaginary part of the impedance at the i-th sampling point.

[0164] The curvature Ki of each sampling point on the complex plane trajectory curve can be calculated using formulas (1-6) to (1-10). All curvature Ki are then divided into M intervals of equal width, and the probability of each interval is calculated. For example, 10 (M) intervals of equal width can be divided, and the number of times curvature Ki falls within each interval can be counted as the number of curvature points falling within each interval. Dividing this number of curvature points by the total number of curvature points (the total number of curvature Ki, which equals the total number of sampling points) yields the interval probability.

[0165] The formula for calculating interval probability is:

[0166] (1-11);

[0167] Where pj is the interval probability of the j-th interval; nj is the number of curvature points falling in the j-th interval; and N is the total number of curvature points.

[0168] The curvature information entropy is calculated as follows:

[0169] (1-12);

[0170] Curvature information entropy is extremely sensitive to minute changes in the local shape of a trajectory, and can effectively detect changes in the geometric features of the Nyquist plot caused by local deformation of the battery casing, thus enabling early deformation warning.

[0171] Based on formulas (1-6) to (1-12), the curvature information entropy of the first complex plane trajectory curve and the second complex plane trajectory curve can be calculated as H1 and H2, respectively. The difference in curvature information entropy between the first complex plane trajectory curve and the second complex plane trajectory curve is calculated as ΔHk=∣H1-H2∣.

[0172] The formula for calculating the deformation sensitivity factor is as follows:

[0173] (1-13);

[0174] The weighting coefficients w1, w2, and w3 were determined through optimization using experimental data, satisfying w1 + w2 + w3 = 1.

[0175] Deformation-sensitive factors are used for detection. Geometric features are extremely sensitive to minute distortions in the trajectory, making it very suitable for detecting early and minute deformations, and it has high sensitivity. By calculating the deformation-sensitive factor through geometric factor fusion, the accuracy of detection is improved.

[0176] In some embodiments, such as Figure 11 As shown, the second complex plane trajectory curve of the qualified battery cell is curve 111, the first complex plane trajectory curve of the third battery cell to be tested is curve 112, and the first complex plane trajectory curve of the fourth battery cell to be tested is curve 113. Curves 111, 112, and 113 can display impedance characteristics in the complex plane, with obvious geometric features; the deformation of the battery cell casing will cause changes in the position, size, and shape of the arc of the curve.

[0177] Based on curves 111, 112, and 113, multiple geometric feature differences between the first and second complex plane trajectory curves can be determined, including the rate of change of trajectory area, the centroid coordinate offset distance, and the difference in curvature entropy. A weighted sum is calculated based on these geometric feature differences and their corresponding weighting coefficients to obtain a deformation sensitivity factor. This deformation sensitivity factor can be used as a comprehensive deformation indicator. Figure 12 As shown, the value of the deformation sensitivity factor is a comprehensive deformation indication. Based on the value of the deformation sensitivity factor and the preset damage quantification relationship, it can be determined that the casing of the battery cell with a comprehensive deformation indication of 11.1 has uniform expansion damage, and the casing of the battery cell with a comprehensive deformation indication of 20.9 has local bulging damage.

[0178] In some embodiments, such as Figure 13As shown, this disclosure provides a battery cell casing testing device, which is applied to testing and analysis equipment, including an excitation control module 131, a signal receiving module 132, an impedance spectrum generation module 133, and a detection processing module 134.

[0179] The excitation control module 131 controls the impedance measuring device to output a first excitation signal to the piezoelectric transducer. The piezoelectric transducer converts the first excitation signal into mechanical vibration and transmits it to the battery cell under test. The signal receiving module 132 receives the second excitation signal collected by the piezoelectric transducer through the impedance measuring device. The piezoelectric transducer converts the mechanical vibration of the battery cell under test into an electrical signal and generates the second excitation signal.

[0180] The impedance spectrum generation module 133 generates the first impedance spectrum of the cell to be tested based on the second excitation signal; the detection processing module 134 determines the detection result for the cell to be tested based on the first impedance spectrum and the second impedance spectrum of the qualified cell corresponding to the cell to be tested.

[0181] In some embodiments, the excitation control module 131 controls the impedance measuring device to output a first excitation signal to the piezoelectric transducer, which converts the first excitation signal into mechanical vibration and transmits it to the qualified battery cell; the signal receiving module 132 receives the third excitation signal collected by the piezoelectric transducer through the impedance measuring device, which converts the mechanical vibration of the qualified battery cell into an electrical signal to generate the third excitation signal; the impedance spectrum generation module 133 generates a second impedance spectrum based on the third excitation signal.

[0182] like Figure 14 As shown, the detection processing module 134 includes a first processing unit 1341 and a second processing unit 1342. The first processing unit 1341 determines the resonance peak difference information of the first impedance spectrum and the second impedance spectrum. The resonance peak difference information includes frequency shift information and / or amplitude change information of the same order resonance peaks. The first processing unit 1341 uses the resonance peak difference information to determine the detection result.

[0183] The first processing unit 1341 determines the resonance peak difference information of each resonance peak in at least two order resonance peaks based on the first impedance spectrum and the second impedance spectrum. The first processing unit 1341 determines the resonance peak reference information corresponding to each resonance peak in at least two order resonance peaks, the resonance peak reference information including the resonance peak frequency and / or resonance peak amplitude in the second impedance spectrum; the first processing unit 1341 determines the detection result based on the resonance peak difference information of each resonance peak in at least two order resonance peaks and the corresponding resonance peak reference information.

[0184] The second processing unit 1342 determines the real part and the imaginary part of the first impedance based on the first impedance spectrum; the second processing unit 1342 constructs a first complex plane trajectory curve based on the real part and the imaginary part of the first impedance; the second processing unit 1342 determines the real part and the imaginary part of the second impedance based on the second impedance spectrum; the second processing unit 1342 constructs a second complex plane trajectory curve based on the real part and the imaginary part of the second impedance; the second processing unit 1342 determines the detection result based on the first complex plane trajectory curve and the second complex plane trajectory curve.

[0185] The second processing unit 1342 determines multiple geometric feature difference information based on the first complex plane trajectory curve and the second complex plane trajectory curve; the second processing unit 1342 determines a deformation sensitivity factor based on the multiple geometric feature difference information; for example, the second processing unit 1342 obtains the weight coefficient of each geometric feature difference information in the multiple geometric feature difference information, calculates a weighted sum based on the multiple geometric feature difference information and the corresponding weight coefficients, and uses it as the deformation sensitivity factor. The second processing unit 1342 determines the detection result based on the deformation sensitivity factor.

[0186] Figure 15 The diagram shows some embodiments of the battery cell casing testing apparatus according to this disclosure, which is applied to testing and analysis equipment. Figure 15 As shown, the electronic device may include a memory 1501, a processor 1502, a communication interface 1503, and a bus 1504. The memory 1501 is used to store instructions, and the processor 1502 is coupled to the memory 1501. The processor 1502 is configured to execute the above-described cell detection method based on the instructions stored in the memory 1501.

[0187] The memory 1501 can be a high-speed RAM, non-volatile memory, or a memory array. The memory 151 may also be divided into blocks, and these blocks can be combined into virtual volumes according to certain rules. The processor 1502 can be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the cell detection method of this disclosure.

[0188] In some embodiments, this disclosure provides a testing and analysis device, including the cell casing testing device as described in any of the above embodiments.

[0189] In some embodiments, such as Figure 16As shown, this disclosure provides a detection system, including a detection and analysis device 161, an impedance measurement device 162, and a piezoelectric transducer 163, for detecting a battery cell 164; the detection and analysis device 161 is the detection and analysis device in any of the above embodiments.

[0190] In some embodiments, this disclosure provides a computer-readable storage medium storing computer instructions that are executed by a processor as described in any of the above embodiments for cell detection.

[0191] Computer-readable storage media may take the form of any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may, for example, include, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples (not an exhaustive list) of readable storage media may include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0192] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0193] Embodiments of this disclosure may also be computer program products, including computer program instructions that, when executed by a processor, cause the processor to perform the steps in the cell detection methods according to various embodiments of this disclosure as described in the "Exemplary Methods" section above.

[0194] The steps of the methods disclosed herein are not limited to the specific order described above, unless otherwise specifically stated. Furthermore, in some embodiments, this disclosure may also be implemented as a program recorded on a recording medium, the program including machine-readable instructions for implementing the methods according to this disclosure. Therefore, this disclosure also covers recording media storing programs for performing the methods according to this disclosure.

[0195] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for detecting an electric cell, applied to a detection and analysis device, characterized in that, The method comprises the following steps: controlling an impedance measurement device to output a first excitation signal to a piezoelectric transducer, wherein the piezoelectric transducer converts the first excitation signal into mechanical vibration and transmits it to the battery to be detected; receiving a second excitation signal collected by the piezoelectric transducer through the impedance measurement device, wherein the piezoelectric transducer converts the mechanical vibration of the battery to be detected into an electrical signal to generate the second excitation signal; generating a first impedance spectrum of the battery to be detected according to the second excitation signal; determining a detection result of the battery to be detected according to the first impedance spectrum and a second impedance spectrum of a qualified battery corresponding to the battery to be detected; wherein the determination of the detection result of the battery to be detected according to the first impedance spectrum and the second impedance spectrum of the qualified battery corresponding to the battery to be detected comprises: determining a first impedance real part and a first impedance imaginary part according to the first impedance spectrum; constructing a first complex plane trajectory curve according to the first impedance real part and the first impedance imaginary part; determining a second impedance real part and a second impedance imaginary part according to the second impedance spectrum; constructing a second complex plane trajectory curve according to the second impedance real part and the second impedance imaginary part; determining a plurality of geometric feature difference information according to the first complex plane trajectory curve and the second complex plane trajectory curve; obtaining a weight coefficient of each geometric feature difference information in the plurality of geometric feature difference information; calculating a weighted sum of the plurality of geometric feature difference information and the corresponding weight coefficient as a deformation sensitivity factor; determining the detection result according to the deformation sensitivity factor.

2. The battery detection method of claim 1, wherein the plurality of geometric feature difference information comprises a trajectory area change rate, a barycenter coordinate offset distance, and a difference value of curvature information entropy between the first complex plane trajectory curve and the second complex plane trajectory curve.

3. The cell detection method of claim 1, wherein, The determination of the detection result of the battery to be detected according to the first impedance spectrum and the second impedance spectrum of the qualified battery corresponding to the battery to be detected comprises: determining resonance peak difference information of the first impedance spectrum and the second impedance spectrum, wherein the resonance peak difference information comprises frequency offset information and / or amplitude change information of the same order resonance peak; determining the detection result by using the resonance peak difference information.

4. The method of claim 3, wherein, The determination of the resonance peak difference information of the first impedance spectrum and the second impedance spectrum comprises: determining the resonance peak difference information of each order resonance peak in at least two order resonance peaks according to the first impedance spectrum and the second impedance spectrum.

5. The method of claim 4, wherein, The determination of the detection result by using the resonance peak difference information comprises: determining resonance peak reference information corresponding to each order resonance peak in the at least two order resonance peaks, wherein the resonance peak reference information comprises a resonance peak frequency and / or a resonance peak amplitude in the second impedance spectrum; determining the detection result according to the resonance peak difference information of each order resonance peak in the at least two order resonance peaks and the corresponding resonance peak reference information.

6. The cell detection method of claim 1, wherein, Further comprising: controlling the impedance measurement device to output the first excitation signal to the piezoelectric transducer device, wherein the piezoelectric transducer device converts the first excitation signal into mechanical vibration and transmits the mechanical vibration to the qualified battery cell; receiving, by the impedance measurement device, a third excitation signal collected by the piezoelectric transducer device, wherein the piezoelectric transducer device converts the mechanical vibration of the qualified battery cell into an electrical signal to generate the third excitation signal; generating the second impedance spectrum according to the third excitation signal.

7. The battery cell detection method of claim 6, wherein the piezoelectric transducer device is arranged at a position including a top of the battery cell to be detected or a top of the qualified battery cell.

8. The battery cell detection method of claim 1, wherein the piezoelectric transducer device includes a first piezoelectric sheet and a second piezoelectric sheet, the first piezoelectric sheet is configured to output the first excitation signal, and the second piezoelectric sheet is configured to collect the second excitation signal.

9. The battery cell detection method of any one of claims 1 to 8, wherein the detection result includes whether the housing of the battery cell to be detected is damaged and damage information. including: an excitation control module configured to control the impedance measurement device to output the first excitation signal to the piezoelectric transducer device, wherein the piezoelectric transducer device converts the first excitation signal into mechanical vibration and transmits the mechanical vibration to the battery cell to be detected; a signal receiving module configured to receive, by the impedance measurement device, a second excitation signal collected by the piezoelectric transducer device, wherein the piezoelectric transducer device converts the mechanical vibration of the battery cell to be detected into an electrical signal to generate the second excitation signal; 10. A battery cell casing detection apparatus applied to a detection analysis device, characterized in that, an impedance spectrum generation module configured to generate a first impedance spectrum of the battery cell to be detected according to the second excitation signal; a detection processing module configured to determine a detection result of the battery cell to be detected according to the first impedance spectrum and a second impedance spectrum of a qualified battery cell corresponding to the battery cell to be detected; wherein the detection processing module includes: a second processing unit configured to determine a first impedance real part and a first impedance imaginary part according to the first impedance spectrum, construct a first complex plane trajectory curve according to the first impedance real part and the first impedance imaginary part, determine a second impedance real part and a second impedance imaginary part according to the second impedance spectrum, construct a second complex plane trajectory curve according to the second impedance real part and the second impedance imaginary part, determine a plurality of geometric feature difference information according to the first complex plane trajectory curve and the second complex plane trajectory curve, obtain a weight coefficient of each geometric feature difference information in the plurality of geometric feature difference information, calculate a weighted sum of the plurality of geometric feature difference information and the corresponding weight coefficient as a deformation sensitivity factor, and determine the detection result according to the deformation sensitivity factor. including: a memory; and a processor coupled to the memory, the processor configured to execute the method of any one of claims 1 to 9 based on instructions stored in the memory.

11. A battery cell casing detection apparatus applied to a detection analysis device, characterized in that, including: the battery cell housing detection device of claim 10 or 11. including:

12. A detection analysis apparatus characterized by comprising: ​ ​ 13. A detection system characterized by, ​ Impedance measuring device, piezoelectric transducer device and detection assay device as claimed in claim 12.

14. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer instructions, and the computer instructions are executed by the processor to perform the method of any one of claims 1 to 9.

15. A computer program product, characterised in that, The computer program product stores computer instructions, and the computer instructions are executed by the processor to perform the method of any one of claims 1 to 9.

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