Lithium-ion battery failure analysis method and device, electronic device, and program product

Abstract

This invention provides a lithium-ion battery failure analysis method, apparatus, electronic device, and program product, relating to the field of battery safety assessment technology. The lithium-ion battery failure analysis method includes: acquiring voltage signals and acoustic emission signals to obtain voltage signal time series and acoustic emission signal time series; determining the electrical response time from the voltage signal time series and the mechanical response time from the acoustic emission signal time series; calculating the time difference between the mechanical response time and the electrical response time; and determining the failure mode of the lithium-ion battery based on the time difference. This solves the technical problem that related battery failure analysis methods cannot accurately determine battery failure modes.

Description

Technical Field

[0001] This invention relates to the field of battery safety assessment technology, and more specifically, to a lithium-ion battery failure analysis method and apparatus, electronic equipment, and program product. Background Technology

[0002] Lithium-ion batteries, with their advantages of high energy density, long cycle life, and low self-discharge rate, have become the main power source for electric vehicles, energy storage systems, and portable electronic devices. However, with the widespread application of batteries under complex operating conditions, their safety hazards are becoming increasingly prominent, among which serious accidents such as fires and explosions caused by thermal runaway are a major focus of industry attention.

[0003] In related technologies, the technical means for lithium-ion battery failure analysis mainly focus on macroscopic performance monitoring and final result judgment. Existing detection methods typically rely on abrupt changes in macroscopic electrical or thermal signals such as voltage, current, and temperature to determine whether the battery has failed. This analytical approach has significant drawbacks: it emphasizes results over process, lacks mechanistic-level diagnostic capabilities, and cannot accurately determine the battery failure mode. This is because most methods only focus on the "final result" of battery failure (such as whether it catches fire, explodes, or the voltage drops to zero), without reconstructing the dynamic process of failure. This black-box judgment method makes it impossible to distinguish specific failure modes, making it difficult to support targeted design improvements. When faced with failure cases, it is difficult to formulate precise improvement plans; for example, it is impossible to determine whether to focus on improving the mechanical strength of the separator or optimizing the tab structure to suppress early short circuits. Summary of the Invention

[0004] The main objective of this invention is to provide a lithium-ion battery failure analysis method, apparatus, electronic device, and program product to solve the technical problem that battery failure analysis methods in related technologies cannot accurately determine battery failure modes.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for analyzing the failure of a lithium-ion battery is provided, comprising: acquiring voltage signals and acoustic emission signals to obtain voltage signal time series and acoustic emission signal time series; determining the electrical response time from the voltage signal time series and the mechanical response time from the acoustic emission signal time series; calculating the time difference between the mechanical response time and the electrical response time; and determining the failure mode of the lithium-ion battery based on the time difference.

[0006] Optionally, the step of acquiring voltage signals and acoustic emission signals to obtain voltage signal time series and acoustic emission signal time series includes: acquiring battery voltage signals at a sampling frequency greater than or equal to 100 kHz to obtain the voltage signal time series; acquiring acoustic emission signals at a sampling frequency greater than or equal to 2 MHz to obtain the acoustic emission signal time series; and performing time synchronization processing on the voltage signal time series and the acoustic emission signal time series to ensure that the time synchronization accuracy between the voltage signal acquisition and the acoustic emission signal acquisition is less than or equal to one microsecond.

[0007] Optionally, the step of determining the electrical response time from the voltage signal time series includes: splitting the voltage signal time series according to a preset time interval to obtain multiple voltage signal subsequences; for each voltage signal subsequence, obtaining the voltage difference of the voltage signal subsequence, calculating the first derivative based on the voltage difference and the preset time interval; if the value of the first derivative is lower than a preset voltage difference evaluation threshold, marking the last moment of the voltage signal subsequence as the electrical response time.

[0008] Optionally, the step of determining the mechanical response time from the acoustic emission signal time series includes: extracting an envelope from the acoustic emission signal time series, comparing each acoustic peak value in the extracted envelope with a preset acoustic threshold value, and marking the mechanical response time according to the comparison result.

[0009] Optionally, the step of marking the mechanical response time based on the comparison result includes: marking the mechanical response time when any peak value in the envelope exceeds the preset sound value threshold and the center frequency of the envelope is in the range of 100-200kHz.

[0010] Optionally, the step of calculating the time difference between the mechanical response time and the electrical response time includes: subtracting the electrical response time from the mechanical response time to calculate the time difference.

[0011] Optionally, the step of determining the failure mode of a lithium-ion battery based on the time difference includes: comparing the time difference with a preset time window threshold; if the time difference is less than a negative time window threshold, determining it as a separator-preferred rupture failure mode, wherein the separator-preferred rupture failure mode includes: separator rupture of the lithium battery taking precedence over internal short circuit; if the absolute value of the time difference is less than or equal to the time window threshold, determining it as a direct short circuit failure mode; if the time difference is greater than the time window threshold, determining it as an electrothermal coupling-induced failure mode.

[0012] According to another aspect of the present invention, a lithium-ion battery failure analysis apparatus is provided, comprising: a signal acquisition unit for acquiring voltage signals and acoustic emission signals to obtain voltage signal time series and acoustic emission signal time series; a response time determination unit for determining electrical response time from voltage signal time series and mechanical response time from acoustic emission signal time series; a time difference calculation unit for calculating the time difference between mechanical response time and electrical response time; and a failure mode determination unit for determining the failure mode of the lithium-ion battery based on the time difference.

[0013] Optionally, the signal acquisition unit includes: a first sampling module for acquiring the battery voltage signal at a sampling frequency greater than or equal to 100 kHz to obtain the voltage signal time series; a second sampling module for acquiring the acoustic emission signal at a sampling frequency greater than or equal to 2 MHz to obtain the acoustic emission signal time series; and a signal synchronization module for performing time synchronization processing on the voltage signal time series and the acoustic emission signal time series to ensure that the time synchronization accuracy between the voltage signal acquisition and the acoustic emission signal acquisition is less than or equal to one microsecond.

[0014] Optionally, the response time determination unit includes: a signal splitting module, used to split the voltage signal time series according to a preset time interval to obtain multiple voltage signal subsequences; a first derivative calculation module, used to obtain the voltage difference of each voltage signal subsequence and calculate the first derivative based on the voltage difference and the preset time interval; and an electrical response time marking module, used to mark the last moment of the voltage signal subsequence as the electrical response time when the first derivative value is lower than a preset voltage difference evaluation threshold.

[0015] Optionally, the response time determination unit includes: an envelope extraction module, used to extract the envelope of the acoustic emission signal time series and compare each acoustic peak value in the extracted envelope with a preset acoustic threshold value; and a mechanical response time marking module, used to mark the mechanical response time according to the comparison result.

[0016] Optionally, the mechanical response time marking module includes a mechanical response time marking submodule, used to mark the mechanical response time when any peak value of a sound value in the envelope exceeds the preset sound value threshold and the center frequency of the envelope is in the range of 100-200kHz.

[0017] Optionally, the time difference calculation unit includes: a time difference calculation module, used to subtract the electrical response time from the mechanical response time to calculate the time difference value.

[0018] Optionally, the failure mode determination unit includes: a time comparison module for comparing the time difference with a preset time window threshold; a first failure mode determination module for determining a membrane-priority rupture failure mode if the time difference is less than a negative time window threshold, wherein the membrane-priority rupture failure mode includes: membrane rupture of the lithium battery taking precedence over internal short circuit; a second failure mode determination module for determining a direct short circuit failure mode if the absolute value of the time difference is less than or equal to the time window threshold; and a third failure mode determination module for determining an electrothermal coupling-induced failure mode if the time difference is greater than the time window threshold.

[0019] According to another aspect of the present invention, an electronic device is provided, comprising one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the lithium-ion battery failure analysis method described in any of the preceding claims.

[0020] According to another aspect of the present invention, a computer program product is provided, comprising a computer program that, when executed by a processor, implements the steps of the lithium-ion battery failure analysis method described in any of the preceding claims.

[0021] By applying the technical solution of this invention, voltage signals and acoustic emission signals can be acquired simultaneously. Then, by determining the electrical response time and mechanical response time, the time difference is calculated. Based on the time difference, the failure mode of the lithium-ion battery is determined, upgrading the failure analysis from qualitative judgment to quantitative diagnosis. By accurately capturing the start time, timing characteristics, and failure mode of the internal short circuit, the causal relationship between structural damage and electrical response is clarified, and the battery failure mode is accurately determined. This solves the technical problem that battery failure analysis methods in related technologies cannot accurately determine the battery failure mode. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 This is a flowchart of an optional analysis method for a lithium-ion battery according to an embodiment of the present invention;

[0024] Figure 2 This is a flowchart of a lithium-ion battery failure analysis method based on multi-source information time-series fusion according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of a voltage-acoustic emission timing according to an embodiment of the present invention. Figure 1 ;

[0026] Figure 4 This is a schematic diagram of a voltage-acoustic emission timing according to an embodiment of the present invention. Figure 2 ;

[0027] Figure 5 This is a schematic diagram of a voltage-acoustic emission timing according to an embodiment of the present invention. Figure 3 ;

[0028] Figure 6 This is a schematic diagram of a failure mode according to an embodiment of the present invention. Figure 1 ;

[0029] Figure 7 This is a schematic diagram of a failure mode according to an embodiment of the present invention. Figure 2 ;

[0030] Figure 8 This is a schematic diagram of a failure mode according to an embodiment of the present invention. Figure 3 ;

[0031] Figure 9 This is a schematic diagram of the spatial distribution of an optional sensor on a cylindrical battery according to an embodiment of the present invention; and

[0032] Figure 10 This is a schematic diagram of a lithium-ion battery failure analysis device according to the present invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0036] To facilitate understanding of the present invention by those skilled in the art, some terms or nouns involved in the various embodiments of the present invention are explained below:

[0037] An internal short circuit (ISC) is an abnormal conduction phenomenon between the positive and negative electrodes inside a battery caused by insulation failure, and is the main cause of battery thermal runaway.

[0038] A voltage signal, or V for short, is an electrical signal that reflects changes in battery potential and is used to detect the timing of electrical responses.

[0039] Acoustic emission signal (AE) is the elastic wave signal released when a material deforms or fractures, and is used to detect the moment of mechanical response.

[0040] Time difference, or Δt for short, is the time interval between the mechanical response time and the electrical response time, used to determine the failure mode.

[0041] Electrical Response Time (Tv) is the point in time when a significant change occurs in the voltage signal (such as a sudden change in the first derivative), representing the moment when an internal short circuit occurs.

[0042] Mechanical Response Time (Te) is the point in time when the envelope of the acoustic emission signal exceeds a preset threshold, representing the moment when diaphragm rupture or structural damage occurs.

[0043] Envelope (Env) is a curve that describes the trend of signal amplitude variation and is used to extract characteristic energy or amplitude information of acoustic emission signals.

[0044] The following embodiments of the present invention can be applied to scenarios such as safety assessment of power batteries for new energy vehicles and health monitoring of battery systems in energy storage power stations. For example, they can be applied to material screening and structural optimization in the battery R&D stage, quality consistency testing in the production stage, and failure mechanism research under abuse conditions (such as needle penetration, extrusion, and impact) in testing laboratories.

[0045] This invention upgrades failure analysis from qualitative judgment to quantitative diagnosis by accurately capturing the onset time, timing characteristics, and failure mode of internal short circuits, thus clarifying the causal relationship between structural damage and electrical response. This invention achieves microsecond-level time resolution, precisely locating the onset time of internal short circuits, providing accurate feedback for battery design, and effectively supporting the improvement of battery safety and the formulation of design improvement schemes.

[0046] Figure 1 This is a flowchart of an optional analysis method for a lithium-ion battery according to an embodiment of the present invention, such as... Figure 1 As shown, the analysis method for the lithium-ion battery includes the following steps S102 to S104. The present invention will be described in detail below with reference to each implementation step.

[0047] Step S101: Collect voltage signal and acoustic emission signal to obtain voltage signal time series and acoustic emission signal time series.

[0048] This embodiment constructs a multi-source information data foundation by simultaneously acquiring electrical and mechanical response signals of the battery during the stress process. Among them, acquiring voltage signals helps to capture instantaneous changes in the battery's internal potential and reflect the occurrence of electrical faults such as internal short circuits; acquiring acoustic emission signals helps to detect mechanical behaviors of battery materials such as microscopic deformation, crack propagation, or separator rupture under mechanical stress.

[0049] Optionally, the step of acquiring voltage signals and acoustic emission signals to obtain voltage signal time series and acoustic emission signal time series includes: acquiring the battery voltage signal at a sampling frequency greater than or equal to 100 kHz to obtain a voltage signal time series; acquiring the acoustic emission signal at a sampling frequency greater than or equal to 2 MHz to obtain an acoustic emission signal time series; and performing time synchronization processing on the voltage signal time series and the acoustic emission signal time series to make the time synchronization accuracy of voltage signal acquisition and acoustic emission signal acquisition less than or equal to one microsecond.

[0050] It should be noted that setting the sampling frequency of the voltage signal to be greater than or equal to 100 kHz helps to capture the details of rapid electrical events such as voltage abrupt changes and avoids the loss of high-frequency information. Simultaneously, in this embodiment of the invention, the sampling frequency of the acoustic emission signal can be set to be greater than or equal to 2 MHz, which helps to completely record the high-frequency characteristics of the acoustic emission waveform, because acoustic emission signals often contain rich high-frequency components, and a high sampling rate can restore the true form of the signal. Time synchronization processing of the voltage signal time series and the acoustic emission signal time series, with the time synchronization accuracy controlled to less than or equal to one microsecond, helps to eliminate time deviations in multi-channel data acquisition. This high-precision time synchronization processing ensures that the voltage signal acquisition and acoustic emission signal acquisition are strictly aligned on the time axis, thereby accurately calculating the minute time difference between the mechanical response moment and the electrical response moment, providing the necessary timing accuracy guarantee for distinguishing subtle differences in failure modes such as diaphragm rupture, direct short circuit, and electrothermal coupling induction.

[0051] Step S102: Determine the electrical response time from the voltage signal time series and the mechanical response time from the acoustic emission signal time series.

[0052] This embodiment extracts the time points of key physical events characterizing battery failure by processing the acquired raw signal sequence. Determining the electrical response time helps locate the starting point of internal short circuits or potential changes within the battery; determining the mechanical response time helps locate the starting point of structural deformation, separator rupture, or material fracture within the battery.

[0053] Optionally, the step of determining the electrical response time from the voltage signal time series includes: splitting the voltage signal time series according to a preset time interval to obtain multiple voltage signal subsequences; for each voltage signal subsequence, obtaining the voltage difference of the voltage signal subsequence, and calculating the first derivative based on the voltage difference and the preset time interval; if the value of the first derivative is lower than a preset voltage difference evaluation threshold, marking the last moment of the voltage signal subsequence as the electrical response time.

[0054] It should be noted that obtaining the voltage difference of a voltage signal subsequence and calculating the first derivative based on the voltage difference and a preset time interval helps quantify the rate of voltage change over time. The first derivative can sensitively reflect sharp drops or rises in voltage. When the value of the first derivative is lower than a preset voltage difference evaluation threshold, the last moment of the voltage signal subsequence is marked as the electrical response moment, which helps to accurately capture the specific moment when a voltage change occurs.

[0055] Optionally, the step of determining the mechanical response time from the acoustic emission signal time series includes: extracting the envelope of the acoustic emission signal time series, comparing each acoustic peak value in the extracted envelope with a preset acoustic threshold value, and marking the mechanical response time according to the comparison result.

[0056] This embodiment extracts the envelope of the acoustic emission signal, highlighting the trend of signal amplitude change over time, filtering out high-frequency carrier information, and making the overall energy change of the signal more intuitive. Comparing the peak sound value in the envelope with a preset sound value threshold helps identify acoustic events with significant energy and eliminates interference from background noise or weak signals. Marking the mechanical response time based on the comparison results helps determine the starting point of significant changes in the battery structure (such as separator rupture, tab breakage, etc.).

[0057] Optionally, the step of marking the mechanical response time based on the comparison results includes: marking the mechanical response time when any sound value peak in the envelope exceeds a preset sound value threshold and the center frequency of the envelope is in the range of 100-200kHz.

[0058] It should be noted that introducing the center frequency criterion helps to further filter effective mechanical response signals. Acoustic emission signals generated by the rupture of internal battery materials often have specific frequency characteristics. Setting the center frequency within the 100-200kHz range can eliminate non-target signals such as high-frequency electromagnetic interference or low-frequency environmental vibrations. Marking the mechanical response moment when the peak sound value exceeds a threshold and the center frequency falls within this range helps improve the accuracy of identifying real structural damage events, reduces false alarms, and thus more accurately locates the mechanical response moment.

[0059] Step S103: Calculate the time difference between the mechanical response time and the electrical response time.

[0060] Optionally, the step of calculating the time difference between the mechanical response time and the electrical response time includes: subtracting the electrical response time from the mechanical response time to calculate the time difference.

[0061] Step S104: Determine the failure mode of the lithium-ion battery based on the time difference.

[0062] Optionally, the step of determining the failure mode of a lithium-ion battery based on the time difference includes: comparing the time difference with a preset time window threshold; if the time difference is less than a negative time window threshold, determining it as a separator-preferred rupture failure mode, wherein the separator-preferred rupture failure mode includes: the rupture of the lithium battery separator takes precedence over an internal short circuit; if the absolute value of the time difference is less than or equal to the time window threshold, determining it as a direct short circuit failure mode; if the time difference is greater than the time window threshold, determining it as an electrothermal coupling-induced failure mode.

[0063] It should be noted that setting a negative time window threshold is used to define situations where the mechanical response significantly precedes the electrical response. When the time difference is less than this negative time window threshold, it is marked as a membrane-priority rupture failure mode. This helps identify failure scenarios where insufficient mechanical strength of the membrane or localized stress concentration leads to membrane failure, subsequently triggering an internal short circuit. Setting the absolute value of the time difference to be less than or equal to the time window threshold serves as a criterion for direct short-circuit failure modes. This helps identify failure scenarios where mechanical impact directly causes contact between the positive and negative electrodes or instantaneous membrane penetration, resulting in mechanical damage and electrical short circuits occurring almost simultaneously. Setting the time difference to be greater than the time window threshold serves as a criterion for electrothermal coupling-induced failure modes. This helps identify situations where the electrical response precedes the obvious mechanical response. This corresponds to a complex coupling process where localized overheating, dendrite growth, or electrical stress accumulation first leads to material performance degradation or structural damage, ultimately causing failure. Through these three classifications, the main failure mechanisms can be covered, enabling a refined classification of lithium-ion battery failure modes.

[0064] By applying the technical solution of this invention, voltage signals and acoustic emission signals can be acquired simultaneously. Then, by determining the electrical response time and mechanical response time, the time difference is calculated. Based on the time difference, the failure mode of the lithium-ion battery is determined, upgrading the failure analysis from qualitative judgment to quantitative diagnosis. By accurately capturing the start time, timing characteristics, and failure mode of the internal short circuit, the causal relationship between structural damage and electrical response is clarified, and the battery failure mode is accurately determined. This solves the technical problem that battery failure analysis methods in related technologies cannot accurately determine the battery failure mode.

[0065] The present invention will now be described with reference to a specific embodiment.

[0066] The purpose of this invention is to provide a lithium-ion battery failure analysis method and system based on multi-source information time-series fusion. It synchronously acquires voltage signal V and acoustic emission signal AE at the microsecond level, calculates the time difference between the two Δt=Te-Tv, and determines the failure mode based on the sign and magnitude of Δt.

[0067] Figure 2 This is a flowchart of a lithium-ion battery failure analysis method based on multi-source information time-series fusion according to an embodiment of the present invention, such as... Figure 2 As shown, the method includes the following steps:

[0068] Step 201, synchronously acquire data. When mechanical load (impact / needle penetration / extrusion) is applied, acquire voltage V(t) at ≥100kHz and acoustic emission AE(t) at ≥2MHz, with time synchronization accuracy ≤1μs (value determination logic: 100kHz captures microsecond-level voltage changes, 2MHz ensures complete acoustic emission waveform details, and 1μs ensures that the measurement errors of mechanical response time Te and electrical response time Tv do not interfere with failure mode classification).

[0069] in, Figure 2 In this context, Tv represents the electrical response time - the voltage drop start point; Te represents the mechanical response time - the acoustic emission threshold point; Δt represents the time difference; and t0 represents the time window threshold (preferably 0.5ms).

[0070] Step 202, Electrochemical Response Time. Detect the voltage signal V, calculate the first derivative dV / dt, and mark the electrochemical response time Tv when it first falls below -1V / ms (range -0.5 to -2V / ms, preferably -1V / ms).

[0071] Step 203, Mechanical Response Time. Detect the acoustic emission signal AE, extract the envelope of the acoustic emission signal, and mark the mechanical response time Te when the envelope first exceeds the preset threshold of 60dB (the value range can be 50-70dB, preferably 60dB, determined based on background noise statistics) and the center frequency is within the range of 100-200kHz (excluding noise interference).

[0072] Figure 3 This is a schematic diagram of a voltage-acoustic emission timing according to an embodiment of the present invention. Figure 1 ,like Figure 3 As shown, the horizontal axis represents time t, in milliseconds (ms), ranging from 0 to 10 ms; the left vertical axis represents voltage, in volts (V), ranging from 3.6 to 4.2 V; and the right vertical axis represents acoustic emission amplitude, in dB, ranging from 0 to 120 dB. At Te = 4 ms, the acoustic emission envelope first exceeds the threshold of 60 dB, indicating diaphragm rupture. At Tv = 6 ms, the voltage first begins to drop, indicating an internal short circuit. Since Te occurs before TV, therefore, at... Figure 3 The diagram shown is a schematic of the voltage-acoustic emission timing of the diaphragm-preferred rupture type.

[0073] Figure 4 This is a schematic diagram of a voltage-acoustic emission timing according to an embodiment of the present invention. Figure 2Through time series comparison analysis, it can be seen that when Te=4ms, the acoustic emission envelope first exceeds the threshold of 60dB, which represents the diaphragm rupture. When Tv=4.2ms, the voltage first starts to drop, which represents the occurrence of internal short circuit. By comparing the time series, it can be seen that |Δt|=|Te-Tv|=0.2ms≤t0, which is characterized as a direct short circuit.

[0074] Figure 5 This is a schematic diagram of a voltage-acoustic emission timing according to an embodiment of the present invention. Figure 3 Through time series comparison analysis, it can be seen that when Te=6ms, the acoustic emission envelope first exceeds the threshold of 60dB, which represents the diaphragm rupture. When Tv=4ms, the voltage first starts to drop, which represents the occurrence of internal short circuit. By comparing the time series, it can be seen that Δt=Te-Tv=2ms>t0, which is characterized as electrothermal coupling induced type.

[0075] exist Figures 3 to 5 In the diagram, the black line indicates the voltage signal; the blue line indicates the acoustic emission signal; the downward arrow indicates the electrochemical response time, and the upward arrow indicates the mechanical response time. Figure 5 The double-headed arrows indicate the time difference.

[0076] exist Figures 3 to 5 In the example of the diaphragm-preferred rupture type: the black line represents the voltage change over time. The initial voltage is stable at 4.2V and begins to drop at Tv=6ms, which is marked as the electrochemical response time; the blue line represents the acoustic emission signal change over time. It first exceeds the threshold of 60dB at Te=4ms, which is marked as the mechanical response time; the red double arrow represents Δt=Te–Tv=4-6=-2ms.

[0077] Step 204: Calculate the time difference Δt = Te - Tv.

[0078] Step 205, determine the failure mode: Δt < -t0 indicates diaphragm-priority rupture type—force precedes electrical, that is, diaphragm rupture (Te) precedes internal short circuit (Tv), such as... Figure 6 As shown in Mode 1, the physical characteristics are: Te precedes Tv, structural damage (diaphragm rupture) precedes electrical response (internal short circuit), and mechanical events precede electrical events. |Δt|≤t0 indicates a direct short circuit, as shown in... Figure 7 In Mode 2, the physical characteristics are: Te and Tv occur almost simultaneously, structural damage and internal short circuits occur almost simultaneously, and mechanical events and electrical events are synchronized. Δt>t0 indicates an electrothermal coupling induced type, such as... Figure 8 As shown in Mode 3, the physical characteristics are: Tv precedes Te, electrical response (micro-short circuit) precedes structural damage, and electrical events precede mechanical events. Here, t0 is the time window threshold—ranging from 0.1ms to 2ms, preferably 0.5ms.

[0079] Figure 9 This is a schematic diagram of the spatial distribution of an optional sensor on a cylindrical battery according to an embodiment of the present invention, as shown below. Figure 9 The image shown is a three-dimensional isometric view, with the right side showing the unfolded side view. Items ③④⑤⑥ are acoustic emission sensors, distributed along the axial and circumferential directions of the battery casing. Item ③ is located at the top, ④⑤ at the middle (circumferential angle 120°), and ⑥ at the bottom. Item ② is a temperature sensor located next to the positive electrode. Items ①⑦ are voltage probes, connected to the positive electrode cap and the negative electrode casing respectively, using a ring spring probe assembly to achieve a four-wire Kelvin connection.

[0080] Through the above embodiments, failure modes can be classified into three categories, failure mechanisms can be identified, and improvement directions can be clarified; at the same time, the initiation time of internal short circuit can be accurately located, achieving microsecond-level time resolution.

[0081] Figure 10 This is a schematic diagram of a lithium-ion battery failure analysis device according to the present invention, as shown below. Figure 10 As shown, the lithium plating early warning device for the lithium-ion battery includes: a signal acquisition unit 1001, a response time determination unit 1002, a time difference calculation unit 1003, and a failure mode determination unit 1004.

[0082] The signal acquisition unit 1001 is used to acquire voltage signals and acoustic emission signals to obtain voltage signal time series and acoustic emission signal time series.

[0083] The response time determination unit 1002 is used to determine the electrical response time from the voltage signal time series and the mechanical response time from the acoustic emission signal time series.

[0084] The time difference calculation unit 1003 is used to calculate the time difference between the mechanical response time and the electrical response time;

[0085] The failure mode determination unit 1004 is used to determine the failure mode of the lithium-ion battery based on the time difference.

[0086] Optionally, the signal acquisition unit includes: a first sampling module for acquiring the battery voltage signal at a sampling frequency greater than or equal to 100 kHz to obtain a voltage signal time series; a second sampling module for acquiring the acoustic emission signal at a sampling frequency greater than or equal to 2 MHz to obtain an acoustic emission signal time series; and a signal synchronization module for performing time synchronization processing on the voltage signal time series and the acoustic emission signal time series to ensure that the time synchronization accuracy between the voltage signal acquisition and the acoustic emission signal acquisition is less than or equal to one microsecond.

[0087] Optionally, the response time determination unit includes: a signal splitting module, used to split the voltage signal time series according to a preset time interval to obtain multiple voltage signal subsequences; a first derivative calculation module, used to obtain the voltage difference of each voltage signal subsequence and calculate the first derivative based on the voltage difference and the preset time interval; and an electrical response time marking module, used to mark the last moment of the voltage signal subsequence as the electrical response time when the first derivative value is lower than a preset voltage difference evaluation threshold.

[0088] Optionally, the response time determination unit includes: an envelope extraction module, used to extract the envelope of the acoustic emission signal time series and compare the peak values ​​of each sound value in the extracted envelope with a preset sound value threshold; and a mechanical response time marking module, used to mark the mechanical response time according to the comparison result.

[0089] Optionally, the mechanical response time marking module includes a mechanical response time marking submodule, used to mark the mechanical response time when any sound value peak in the envelope exceeds a preset sound value threshold and the center frequency of the envelope is in the range of 100-200kHz.

[0090] Optionally, the time difference calculation unit includes: a time difference calculation module, used to subtract the electrical response time from the mechanical response time to calculate the time difference value.

[0091] Optionally, the failure mode determination unit includes: a time comparison module for comparing the time difference with a preset time window threshold; a first failure mode determination module for determining a membrane-priority rupture failure mode if the time difference is less than a negative time window threshold, wherein the membrane-priority rupture failure mode includes: membrane rupture of the lithium battery taking precedence over internal short circuit; a second failure mode determination module for determining a direct short circuit failure mode if the absolute value of the time difference is less than or equal to the time window threshold; and a third failure mode determination module for determining an electrothermal coupling-induced failure mode if the time difference is greater than the time window threshold.

[0092] According to another aspect of the present invention, an electronic device is provided, comprising one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the lithium-ion battery failure analysis method described above.

[0093] According to another aspect of the present invention, a computer program product is provided, comprising a computer program that, when executed by a processor, implements the steps of the lithium-ion battery failure analysis method described above.

[0094] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: They can clearly distinguish between three main failure modes: membrane-preferred rupture, direct short circuit, and electrothermal coupling-induced failure. By quantifying the sequence of mechanical and electrical responses, the previously vague qualitative judgments are transformed into precise quantitative diagnoses, thereby revealing the specific physical mechanisms behind the failures and solving the problem that existing technologies cannot distinguish failure modes.

[0095] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: they can accurately clarify the core causal issue of whether structural damage or internal short circuit occurs first, enabling technicians to clearly determine whether mechanical stress directly causes the short circuit, whether diaphragm rupture indirectly causes the short circuit, or whether the electrothermal coupling effect dominates the failure.

[0096] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: microsecond-level time resolution of the battery failure process can be achieved, which helps to capture rapidly occurring transient events, accurately locate the start time of internal short circuits, and avoid misjudgment or missed judgment due to low sampling frequency or large synchronization error.

[0097] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0098] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0099] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0100] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for analyzing the failure of lithium-ion batteries, characterized in that, include: Voltage signals and acoustic emission signals are acquired to obtain voltage signal time series and acoustic emission signal time series; The electrical response time is determined from the voltage signal time series, and the mechanical response time is determined from the acoustic emission signal time series; Calculate the time difference between the mechanical response time and the electrical response time; The failure mode of a lithium-ion battery is determined based on the time difference.

2. The lithium-ion battery failure analysis method according to claim 1, characterized in that, The steps for acquiring voltage signals and acoustic emission signals to obtain voltage signal time series and acoustic emission signal time series include: The voltage signal of the battery is acquired at a sampling frequency greater than or equal to 100 kHz to obtain the time series of the voltage signal; Acoustic emission signals are acquired at a sampling frequency greater than or equal to two megahertz to obtain the time series of the acoustic emission signals; The voltage signal time series and the acoustic emission signal time series are time-synchronized to ensure that the time synchronization accuracy between the voltage signal acquisition and the acoustic emission signal acquisition is less than or equal to one microsecond.

3. The lithium-ion battery failure analysis method according to claim 1, characterized in that, The steps for determining the electrical response time from a voltage signal time series include: The voltage signal time series is split according to a preset time interval to obtain multiple voltage signal subsequences; For each voltage signal subsequence, the voltage difference of the voltage signal subsequence is obtained, and the first derivative is calculated based on the voltage difference and the preset time interval; If the first derivative value is lower than a preset voltage difference evaluation threshold, the last moment of the voltage signal subsequence is marked as the electrical response moment.

4. The lithium-ion battery failure analysis method according to claim 1, characterized in that, The steps for determining the mechanical response time from an acoustic emission signal time series include: The envelope of the acoustic emission signal time series is extracted, and the peak values ​​of each sound value in the extracted envelope are compared with a preset sound value threshold. The mechanical response time is marked based on the comparison results.

5. The lithium-ion battery failure analysis method according to claim 4, characterized in that, The step of marking the mechanical response time based on the comparison results includes: The mechanical response time is marked when any peak value in the envelope exceeds the preset sound value threshold and the center frequency of the envelope is in the range of 100-200kHz.

6. The lithium-ion battery failure analysis method according to claim 1, characterized in that, The steps for calculating the time difference between the mechanical response time and the electrical response time include: The time difference is calculated by subtracting the electrical response time from the mechanical response time.

7. The lithium-ion battery failure analysis method according to claim 1, characterized in that, The steps for determining the failure mode of a lithium-ion battery based on the time difference include: Compare the time difference with a preset time window threshold; If the time difference is less than the negative time window threshold, it is determined to be a membrane-priority rupture failure mode, wherein the membrane-priority rupture failure mode includes: the rupture of the lithium battery membrane takes precedence over the internal short circuit of the battery. If the absolute value of the time difference is less than or equal to the time window threshold, it is determined to be a direct short-circuit failure mode; If the time difference is greater than the time window threshold, it is determined to be an electrothermal coupling-induced failure mode.

8. A lithium-ion battery failure analysis device, characterized in that, include: The signal acquisition unit is used to acquire voltage signals and acoustic emission signals to obtain voltage signal time series and acoustic emission signal time series. The response time determination unit is used to determine the electrical response time from the voltage signal time series and the mechanical response time from the acoustic emission signal time series. The time difference calculation unit is used to calculate the time difference between the mechanical response time and the electrical response time; The failure mode determination unit is used to determine the failure mode of the lithium-ion battery based on the time difference.

9. An electronic device, characterized in that, The method includes one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the lithium-ion battery failure analysis method according to any one of claims 1 to 7.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the lithium-ion battery failure analysis method according to any one of claims 1 to 7.

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