Expansion extrusion force monitoring method and device based on cylindrical cell clamping groove adaptation

Abstract

The invention relates to the technical field of battery pressure monitoring, and particularly discloses an expansion extrusion force monitoring method and device based on cylindrical battery cell clamping groove adaptation, and the method provides an expansion extrusion force monitoring method and device based on cylindrical battery cell clamping groove adaptation through an integrated and intelligent monitoring strategy. The safety and reliability of the cylindrical battery cell in the charging and discharging cycle process are remarkably improved, the thermal runaway early warning sensor arranged at the clamping groove position of the cylindrical battery cell achieves real-time and accurate sensing of microscopic expansion deformation of the cylindrical battery cell, reversible expansion caused by normal charging and discharging is effectively discriminated, and irreversible expansion indicating internal degradation is effectively indicated. Therefore, accurate early warning is given out at the earliest stage of thermal runaway, and the occurrence probability of serious safety accidents is greatly reduced; and meanwhile, through continuous monitoring of the expansion force trend and the distribution rule, a comprehensive and proactive technical guarantee is finally provided for efficient and safe management of the battery in the whole life cycle.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery pressure monitoring, in particular to an expansion extrusion pressure monitoring method and device based on a cylindrical battery cell clamping groove. BACKGROUND

[0002] In the field of battery pressure monitoring, cylindrical battery cells will expand in volume due to irreversible side reactions during charging and discharging cycles and aging processes. At the same time, the cylindrical battery cells themselves will expand reversibly during the charging and discharging cycle. This complex expansion behavior will generate continuous extrusion pressure on the battery module. In the monitoring of the extrusion pressure of the cylindrical battery cell, a dedicated sensor is used to monitor the extrusion pressure, such as integrating an ultra-thin film pressure sensor inside the module. In order to extract effective information from complex signals, a temperature compensation method is used to preliminarily exclude the influence of monitoring errors caused by temperature, thereby providing an important data basis for evaluating the health status and safety risks of the battery cell.

[0003] For example, the Chinese invention patent with publication number CN113295325B discloses a battery pack pressure monitoring device. The pressure monitoring device and the battery management system communicate bidirectionally to realize bidirectional wake-up between the pressure monitoring device and the battery management system. The battery management system sends a wake-up signal or a sleep signal to the pressure monitoring device to make the pressure monitoring device enter a wake-up state or a sleep state. The pressure monitoring device sends a wake-up signal to the battery management system to make the battery management system enter a wake-up state.

[0004] For example, the Chinese invention patent with publication number CN114964601B discloses a pressure change real-time monitoring device for the inside of a battery. The pressure change real-time monitoring device includes a working electrode, a counter electrode, a wire, and a shell. The working electrode and the counter electrode are both materials with double-layer effects, and the surfaces of the working electrode and the counter electrode are both velvet-like protruding structures. The shell is used to support the working electrode and the counter electrode and arrange them apart. The working electrode and the counter electrode are respectively connected to a wire to lead out the electrical signals on the working electrode and the counter electrode.

[0005] The aforementioned technologies suffer from at least the following technical problems: In the field of battery pressure monitoring technology, temperature compensation methods for monitoring devices typically rely on linear correction using pre-set fixed parameters. This static compensation mode is ill-suited to the complex dynamic conditions of cylindrical cells during actual charging and discharging, resulting from the combined effects of internal electrochemical reactions, heat generation fluctuations, and environmental changes. This leads to significant drift in the compensated pressure monitoring data. Furthermore, traditional monitoring methods generally rely on isolated real-time acquisition of pressure values ​​and comparison with simple thresholds. This judgment mechanism ignores the normal, reversible thickness changes in the cell caused by lithium-ion insertion / extraction during cycling, failing to correlate pressure changes with the cell's own operating parameters. These limitations make it difficult for the monitoring system to effectively distinguish between benign expansion caused by normal charging and discharging and abnormal expansion caused by internal decay. This not only reduces the accuracy of cell health assessment but also significantly increases the false alarm rate of safety warnings due to the inability to identify the nature of the expansion, severely restricting the reliability and intelligence level of the battery management system. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method and device for monitoring expansion and compression pressure based on cylindrical battery cell slot adaptation, which can effectively solve the problems mentioned in the background technology.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of the present invention provides an expansion and extrusion pressure monitoring method based on cylindrical cell slot adaptation, comprising: S1. Marking each expansion and extrusion pressure monitoring device deployed at each cylindrical cell slot position as a monitoring device, each monitoring device monitoring the expansion and extrusion pressure and real-time temperature at each cylindrical cell slot position in real time, compensating the expansion and extrusion pressure at each cylindrical cell slot position monitored by each monitoring device in real time with the real-time temperature to obtain temperature compensation pressure, and initializing the temperature compensation parameters of each monitoring device.

[0008] S2. If a monitoring device monitors the expansion pressure at the slot of a cylindrical battery cell in real time and it is greater than or equal to the upper limit of the expansion pressure preset in the monitoring database, the device identifies and analyzes the operating status of each cylindrical battery cell monitored by the monitoring device. Based on the analysis results of the operating status of a cylindrical battery cell, the device determines whether the cylindrical battery cell is undergoing reversible expansion. If the cylindrical battery cell is determined to be undergoing reversible expansion, the monitoring device at the slot of the cylindrical battery cell is marked as an over-limit monitoring device, and the over-limit duration of the over-limit monitoring device is recorded. If the cylindrical battery cell is determined not to be undergoing reversible expansion, a thermal runaway warning is issued for the cylindrical battery cell.

[0009] S3. Obtain and analyze the over-limit duration and distribution of each over-limit monitoring device, and determine whether to issue a thermal risk warning for the cylindrical battery cell based on the analysis results.

[0010] The second aspect of the application provides an expansion extrusion force monitoring device based on a cylindrical cell card slot adaptation, comprising: a thermal runaway early warning sensor and a sensor fixing clamp; the thermal runaway early warning sensor is a super-thin flexible sensor used to monitor the expansion extrusion force between the two cylindrical cells at the cylindrical cell card slot position, and the expansion extrusion force between the two cylindrical cells at the cylindrical cell card slot position is monitored in real time by the internal pressure sensitive function layer resistance; the sensor fixing clamp is a concave arc surface card slot used to fix the thermal runaway early warning sensor, and the concave arc surface is tightly wrapped and fixed on the outer wall of the cylindrical cell by pasting a pair of sensor fixing clamps along the radial direction of the cell, so that the thermal runaway early warning sensor is fixed at the card slot adaptation position of the cylindrical cell.

[0011] Compared with the prior art, the embodiments of the application have at least the following advantages or beneficial effects:

[0012] (1) The application provides an expansion extrusion force monitoring method and device based on a cylindrical cell card slot adaptation, which significantly improves the safety and reliability of the cylindrical cell during the charging and discharging cycle by using integrated and intelligent monitoring strategies. The thermal runaway early warning sensor deployed at the cylindrical cell card slot position realizes real-time and accurate perception of the microscopic expansion deformation of the cylindrical cell. By introducing a temperature compensation mechanism and a multi-parameter fusion analysis model, a dynamic and adaptive safety protection system is constructed. This system can effectively distinguish between reversible expansion caused by normal charging and discharging and irreversible expansion indicating internal degradation, thereby issuing accurate early warnings in the earliest stage of thermal runaway, greatly reducing the probability of serious safety accidents. At the same time, the method helps to optimize the charging and discharging strategy and thermal management control by continuously monitoring the expansion force trend and distribution law, which slows down the aging rate of the cell from the root cause and significantly extends the overall service life of the battery module, ultimately providing comprehensive and forward-looking technical support for efficient and safe management throughout the life cycle of the battery.

[0013] (2) The application introduces a temperature compensation parameter initialization mechanism to effectively overcome the interference of environmental temperature fluctuations on pressure monitoring, ensuring the accuracy and stability of data acquisition. The method first initializes the matching temperature compensation parameters by querying the pre-set temperature compensation drift compensation mapping table when the system starts. During continuous operation, the system uses real-time temperature data to dynamically compensate and correct the original pressure signal. This process effectively eliminates the nonlinear measurement error caused by the sensor itself and the measurement environment thermal drift, making the expansion extrusion force data obtained from different environments and different times have a unified reference and comparability. The original pressure signal is sublimated into a reliable state parameter, which provides a solid and reliable data foundation for subsequent accurate risk level determination, abnormal pattern recognition and thermal runaway early warning.

[0014] (3)The application can accurately distinguish between reversible expansion and irreversible expansion by constructing a set of refined diagnostic logic. The core of this accurate discrimination ability is that it does not rely on a single pressure threshold, but comprehensively analyzes the dynamic evolution trend of multiple key state parameters such as expansion extrusion pressure change rate, pressure fluctuation frequency and charge transfer impedance. By introducing a weight contribution coefficient to couple these parameters, the system generates a quantitative expansion risk index that can sensitively capture the weak signs of early performance degradation of the battery cell. On this basis, further analysis of abnormal conditions enables the system to understand the underlying causes of the abnormality. Based on this in-depth analysis, the system can implement differentiated early warning strategies: for reversible expansion, record and monitor the over-limit duration; for irreversible expansion, immediately trigger the highest level of thermal runaway alarm. This process completely changes the passive response mode in traditional battery safety management, which often lags behind the occurrence of faults, and realizes a fundamental change from post-remediation to pre-intervention, greatly improving the predictability, accuracy and operation efficiency of safety management, while effectively avoiding false alarms caused by normal battery expansion, reducing unnecessary system interruptions and maintenance costs.

[0015] (4)The application realizes early prediction and systematic control of the thermal risk diffusion trend in the cylindrical cell group through comprehensive evaluation of over-limit duration and spatial distribution. The core is to analyze the abnormal state of a single cell in the overall space-time background of the module. This risk analysis mechanism can sensitively capture the synchronous growth trend of the over-limit duration of multiple cylindrical cells in the time dimension, or the adjacent expansion mode of the abnormal area in the space dimension, which is often a critical precursor of thermal runaway chain reaction, thereby issuing a spatially directed thermal risk warning, greatly enhancing the containment capability of overall thermal failure, thereby improving the overall safety redundancy of the battery system while upgrading the operation and management from passive disposal to proactive and intelligent decision-making based on risk situation awareness. BRIEF DESCRIPTION OF DRAWINGS

[0016] The application is further illustrated by the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the application. For ordinary skilled persons in the art, other drawings can be obtained without creative labor on the basis of the following drawings.

[0017] Figure 1 The application is further illustrated by the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the application. For ordinary skilled persons in the art, other drawings can be obtained without creative labor on the basis of the following drawings.

[0018] Figure 2 The application is further illustrated by the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the application. For ordinary skilled persons in the art, other drawings can be obtained without creative labor on the basis of the following drawings.

[0019] Figure 3 The application is further illustrated by the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the application. For ordinary skilled persons in the art, other drawings can be obtained without creative labor on the basis of the following drawings.

[0020] Figure 4 A schematic diagram of a heat risk grading early warning and prevention decision-making process of the present application. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0022] Referring to Figure 1 As shown in the drawings, the first aspect of the present application provides a swelling extrusion force monitoring method based on cylindrical cell slot adaptation, comprising: S1. marking each swelling extrusion force monitoring device deployed at each cylindrical cell slot position as each monitoring device, each monitoring device monitoring the swelling extrusion force and the real-time temperature at each cylindrical cell slot position in real time, compensating the swelling extrusion force at each cylindrical cell slot position monitored by each monitoring device in real time by the real-time temperature to obtain a temperature compensation pressure, and initializing the temperature compensation parameters of each monitoring device.

[0023] S2. If the swelling extrusion force at the cylindrical cell slot position monitored by a certain monitoring device is greater than or equal to the upper limit value of the swelling extrusion force preset in the monitoring database, identify and analyze the operating state of each cylindrical cell monitored by the monitoring device, determine whether the cylindrical cell is reversibly swelling based on the analysis result of the operating state of the cylindrical cell, if it is determined that the cylindrical cell is reversibly swelling, mark the monitoring device at the cylindrical cell slot position as an over-limit monitoring device, and record the over-limit duration of the over-limit monitoring device, if it is determined that the cylindrical cell is not reversibly swelling, perform a thermal runaway early warning on the cylindrical cell.

[0024] S3. Obtain and analyze the over-limit duration and distribution of each over-limit monitoring device, and determine whether to perform a thermal risk early warning on the cylindrical cell based on the analysis result.

[0025] Referring to Figure 2As shown, the temperature compensation parameters of each monitoring device are initialized, and then the operating state parameters of each cylindrical battery cell are acquired in real time, and the expansion risk index RZ of each cylindrical battery cell is calculated accordingly. First, it is determined whether RZ is lower than the preset expansion risk threshold value: if RZ is lower than the preset expansion risk threshold value, it is determined that the cylindrical battery cell operating state is normal; if RZ is not lower than the preset expansion risk threshold value, the deviation value of the expansion risk index is further calculated. When the deviation value exceeds the set upper limit value of the deviation value, the battery cell operating state is directly marked as abnormal; if the deviation value does not exceed the upper limit value of the deviation value, the temperature compensation coefficient of the monitoring device is automatically corrected to improve the accuracy of subsequent monitoring, thereby forming a closed-loop management mechanism of continuous monitoring, risk judgment and parameter self-adaptive adjustment.

[0026] Specifically, the temperature compensation parameters of each monitoring device are initialized, and the specific initialization process is as follows: the real-time temperature is used to compensate the expansion extrusion force at the card slot position of each cylindrical battery cell to obtain the temperature compensation pressure; the real-time temperature of each cylindrical battery cell monitored by each monitoring device is acquired, and the preset temperature compensation drift compensation mapping table in the monitoring database is input to map and output the real-time temperature compensation drift compensation pressure of each monitoring device; each monitoring device is compensated by the real-time temperature compensation drift compensation pressure of each monitoring device, and the temperature compensation parameters of each monitoring device are initialized.

[0027] The above-mentioned real-time temperature refers to the real-time temperature of each monitoring device, that is, the real-time temperature value directly monitored and read by each monitoring device at the card slot position of each cylindrical battery cell. Due to the effect of heat transfer, the real-time temperature value is affected by the adjacent two cylindrical battery cells at the card slot position.

[0028] The above-mentioned temperature compensation pressure refers to the expansion extrusion force compensated by each monitoring device through the real-time temperature.

[0029] The above-mentioned temperature compensation parameters of each monitoring device refer to the compensation data of the corresponding relationship between the expansion extrusion force output value and the temperature change of each monitoring device, which is used to calibrate the expansion extrusion force measurement value of each monitoring device.

[0030] It needs to be explained that the real-time temperature compensation drift compensation pressure of each monitoring device is mapped and output, and the real-time temperature of each cylindrical battery cell monitored by each monitoring device is input to the preset temperature compensation drift compensation mapping table in the monitoring database. The temperature compensation drift mapping table takes the real-time temperature as the index, and stores the preset real-time temperature compensation drift compensation pressure corresponding to the record. The temperature compensation drift compensation mapping table is searched, and the real-time temperature compensation drift compensation pressure of each monitoring device is mapped and output.

[0031] In a specific embodiment, the monitoring devices are compensated by real-time temperature compensation drift compensation pressure of each monitoring device. The system first collects the real-time temperature of each cylindrical battery, for example 25℃ and 40℃, and outputs the corresponding temperature compensation drift compensation pressure (such as 0.5kPa and 1.2kPa) through the mapping table, then applies these compensation pressure values to each monitoring device, adjusts the scaling factor of the monitoring device by differentiating the temperature compensation drift compensation pressure on both sides of the monitoring device, multiplies the expansion and extrusion pressure reading of the monitoring device by the scaling factor to compensate the monitoring device, so that the monitoring device reading can pre-offset the error caused by temperature, after compensation, the temperature compensation parameter is initialized, and the subsequent output of the monitoring device is directly expressed as the temperature compensation pressure, thereby improving the consistency of the data, effectively eliminating the interference caused by temperature effect, separating the pressure reading change of the monitoring device itself and its installation structure caused by thermal expansion and cold contraction from the total signal, so that the pressure data on which the system subsequently judges can accurately reflect the expansion state of the battery itself, significantly improving the accuracy of fault diagnosis, avoiding false alarms or missed alarms caused by environmental temperature fluctuations, initializing and calibrating the compensation parameters of the monitoring device, and establishing the basis for long-term temperature adaptive monitoring.

[0032] Specifically, the running state of each cylindrical battery monitored by the monitoring device is identified and analyzed, and the specific analysis process is as follows: obtaining the running state parameters of each cylindrical battery monitored by the monitoring device.

[0033] The running state parameters of each cylindrical battery include the expansion and extrusion pressure change rate of each cylindrical battery, the pressure fluctuation frequency at the clamping groove position of each cylindrical battery, and the charge transfer impedance of each cylindrical battery.

[0034] The expansion and extrusion pressure change rate of each cylindrical battery refers to the change speed of the extrusion pressure on the external structure of the cylindrical battery due to internal side reactions during charging and discharging, which is used to reflect the severity of the internal side reactions of the cylindrical battery, and can be obtained by real-time acquisition of expansion and extrusion pressure data by the monitoring device and differential calculation algorithm processing; the pressure fluctuation frequency at the clamping groove position of each cylindrical battery refers to the fluctuation frequency of the expansion and extrusion pressure signal at the clamping groove position of the cylindrical battery, which is used to identify and analyze specific failure modes, and can be obtained by real-time monitoring of the pressure signal by the monitoring device and signal processing analysis; the charge transfer impedance of each cylindrical battery refers to the resistance encountered when the surface of the cylindrical battery undergoes an electrochemical reaction, which is used to reflect the reaction activity of the electrochemical interface inside the cylindrical battery, and a small amplitude alternating excitation signal of a specific frequency range is applied, and its response is measured to obtain the electrochemical impedance spectrum.

[0035] The coupling factor of the expansion extrusion pressure change rate of each cylindrical battery and the pressure fluctuation frequency at the slot position of each cylindrical battery and the charge transfer impedance factor of each cylindrical battery are quantified by introducing weight contribution coefficients, and the contribution degrees of each cylindrical battery to the expansion risk index are coupled to obtain the expansion risk index of each cylindrical battery, and the specific expression is:

[0036]

[0037] In the formula, RZ is the expansion risk index of each cylindrical battery, pt is the expansion extrusion pressure change rate of each cylindrical battery, f is the pressure fluctuation frequency at the slot position of each cylindrical battery, RT is the charge transfer impedance of each cylindrical battery, pt0 is the critical upper limit value of the expansion extrusion pressure change rate preset in the monitoring database, f0 is the critical upper limit value of the pressure fluctuation frequency preset in the monitoring database, R0 is the reference impedance of the cylindrical battery preset in the monitoring database, w1 is the weight contribution coefficient corresponding to the coupling factor of the expansion extrusion pressure change rate of each cylindrical battery and the pressure fluctuation frequency at the slot position of each cylindrical battery preset in the monitoring database, w2 is the weight contribution coefficient corresponding to the charge transfer impedance factor of each cylindrical battery preset in the monitoring database, α is the adjustment coefficient corresponding to the charge transfer impedance preset in the monitoring database, β is the adjustment coefficient corresponding to the expansion extrusion pressure change rate preset in the monitoring database, and γ is the adjustment coefficient corresponding to the pressure fluctuation frequency preset in the monitoring database.

[0038] It needs to be explained that the adjustment coefficient corresponding to the charge transfer resistance is the coefficient for defining the correlation strength between the deterioration of the electrochemical interface health degree and the expansion risk in the monitoring database. Since the increase of the charge transfer impedance means the decrease of the electrode surface reaction activity and the intensification of the side reaction, which will be the fundamental inducement of gas production and expansion, the adjustment coefficient α determines the sensitivity of the correlation between the deterioration of the electrochemical interface health degree and the expansion risk. Through statistical analysis of a large amount of battery historical data, combined with electrochemical impedance spectroscopy test and synchronous expansion force monitoring data, the adjustment coefficient corresponding to the charge transfer resistance is set and calibrated. Specifically, under controllable conditions in the laboratory, the sample battery is subjected to aging cycles at different rates, and the evolution trajectory of the charge transfer impedance and the expansion force data at the corresponding time are measured regularly. By using regression analysis and other means, the expected increase of the expansion risk caused by the increase of one unit of impedance is quantified to determine the reference value of the adjustment coefficient corresponding to the charge transfer resistance. This reference value also needs to be continuously fine-tuned and optimized in the real battery pack operation database according to the accuracy and false alarm rate of the actual early warning, and finally a dynamic parameter that can accurately reflect the electrochemical-mechanical coupling relationship of a specific type of battery is formed.

[0039] It needs to be explained that the adjustment coefficient corresponding to the expansion extrusion rate is the coefficient for monitoring the database to define the correlation strength between the preset mechanical pressure mutation speed and the expansion risk. Since the sharp increase in the expansion extrusion rate is the most direct and macro physical manifestation of the intensification of the internal side reaction of the cylindrical battery, it is the critical precursor of thermal runaway, and the adjustment coefficient β determines the sensitivity of the correlation between the mechanical pressure mutation and the expansion risk. By analyzing a large amount of thermal runaway test data, it can be observed that the pressure change rate will cross a critical threshold before runaway. The initial value of the adjustment coefficient corresponding to the expansion extrusion rate is determined based on the statistics of this critical threshold, and the purpose is to capture this landmark instability signal. Subsequently, in the full life cycle monitoring of the battery pack, the system will continuously track the correspondence between abnormal events of pressure rate and whether a failure occurs eventually, and accordingly continuously correct the value of the adjustment coefficient corresponding to the expansion extrusion rate, in order to ensure that the system can both sensitively issue an extreme risk warning and effectively suppress false positives caused by non-critical fluctuations.

[0040] It needs to be explained that the adjustment coefficient corresponding to the pressure fluctuation frequency is the coefficient for monitoring the database to define the correlation characteristics between the defined pressure signal frequency domain features and potential failure modes. Since pressure fluctuations of different frequencies point to completely different failure sources, the adjustment coefficient γ determines the weight of the correlation between specific frequency domain signals and their corresponding risk severity. By setting different γ values, the model can give higher risk amplification weight to the fluctuation signals in a specific frequency band, so that the extreme danger represented by the signal can be effectively captured by the system, thereby achieving fine calibration of the differentiated warning capability for different failure modes. Through targeted experiments or real failure case data collected at high frequency, a strong correlation between specific frequency bands and specific failure modes is established, and the assignment of the adjustment coefficient corresponding to the pressure fluctuation frequency is directly proportional to the confidence of this correlation and the severity of the failure mode. For example, an extremely high frequency micro-fluctuation confirmed as a precursor to internal short circuit will be given a very high adjustment coefficient value corresponding to the pressure fluctuation frequency, ensuring that the system gives enough weight to its extremely high risk. The calibration of this coefficient depends heavily on the continuous improvement of signal processing technology and the failure case library.

[0041] It needs to be explained that the rate of change of the swelling extrusion pressure describes the severity of the pressure change from the time domain dimension, which is a direct manifestation of the rapid release of mechanical energy; while the pressure fluctuation frequency reveals the periodic characteristics contained in the pressure signal from the frequency domain dimension, and the specific frequency component often corresponds to the oscillation mode of the internal side reaction. In the actual thermal runaway development process, the rapid rise of pressure is often accompanied by violent fluctuations of specific frequency, and these two phenomena usually appear together, indicating the aggravation of risk. The purpose of using this special mathematical processing method is to consider the contribution of these two different dimension indicators equally, avoid the excessive dominance of a single indicator, and ensure that even if one parameter is only slightly abnormal and the other parameter shows significant dangerous characteristics, the comprehensive effect can still be sensitively captured and amplified. On the other hand, the increase of charge transfer impedance is a direct manifestation of the deterioration of the health of the electrochemical interface, which means that the main reaction on the electrode surface is blocked, and the side reactions such as lithium deposition and electrolyte decomposition are intensified. These side reactions will directly produce gas and release heat, leading to the rise of internal pressure and uneven temperature distribution of the battery, thus causing rapid changes in swelling extrusion pressure and specific frequency pressure fluctuations on the macro level, thereby making the risk assessment model highly sensitive to both rapid mechanical deformation and specific high-frequency fault signals, and achieving comprehensive and robust assessment of complex swelling risk states.

[0042] The swelling risk index of each cylindrical battery is compared with the swelling risk threshold value. If the swelling risk index of a cylindrical battery is less than the swelling risk threshold value, the running state of the cylindrical battery is normal. If the swelling risk index of a cylindrical battery is greater than or equal to the swelling risk threshold value, the swelling risk deviation value of the cylindrical battery is obtained, and the swelling risk deviation value of the cylindrical battery is compared with the upper limit value of the deviation value.

[0043] Referring to Figure 3 As shown in FIG. 9, first, it is judged whether the corrected RZ is lower than the swelling risk threshold value. If RZ is less than the swelling risk threshold value, continue to monitor; if RZ is greater than or equal to the swelling risk threshold value, determine that the battery running state is abnormal, and further analyze the specific abnormal conditions. If there are abnormal conditions, it is determined as irreversible swelling and triggers thermal runaway warning; if none of the above conditions are met, it is determined as reversible swelling. Finally, the system will mark the related monitoring device as an over-limit state and record the duration, completing the accurate diagnosis and grading warning of the swelling type.

[0044] If the expansion risk index deviation value of the cylindrical battery is greater than or equal to the upper deviation value, the running state of the cylindrical battery is abnormal, and the abnormal condition of the cylindrical battery is analyzed; if the expansion risk index deviation value of the cylindrical battery is less than the upper deviation value, the temperature compensation coefficient of each monitoring device of the cylindrical battery is corrected through the expansion risk index of the cylindrical battery; the expansion risk index of the cylindrical battery after correction is obtained and compared with the expansion risk threshold value, if the expansion risk index of the cylindrical battery after correction is less than the expansion risk threshold value, the running state of the cylindrical battery is normal; if the expansion risk index of the cylindrical battery after correction is greater than the expansion risk threshold value, the running state of the cylindrical battery is abnormal.

[0045] In a specific embodiment, the temperature compensation coefficient of each monitoring device of the cylindrical battery is corrected through the expansion risk index of the cylindrical battery, according to the deviation proportion of the expansion risk index currently calculated by the monitoring device D-07 and the preset threshold value thereof, the preset temperature compensation adjustment coefficient calculation rule in the monitoring database is called, first, the difference between the current expansion risk index of the cylindrical battery and the expansion risk threshold value is calculated, then the difference is divided by the risk threshold value to obtain a ratio representing the relative deviation degree; then the ratio is multiplied by the preset adjustment coefficient in the monitoring database to obtain the actual adjustment amplitude; then the adjustment amplitude is added to the base number 1 to form an adjustment multiplier; finally, the original temperature compensation coefficient is multiplied by the adjustment multiplier to obtain the new temperature compensation coefficient after correction, and then the new temperature compensation coefficient after correction is immediately used to calibrate the original reading from the temperature sensor on the D-07 cylindrical battery, effectively offsetting the interference of environmental temperature fluctuations on the measured value, then using this batch of new data after temperature compensation calibration (including more accurate temperature, expansion and extrusion pressure change rate, etc.), the expansion risk index of the battery D-07 is recalculated, if the index value after this correction falls below the safety threshold value, it is determined that the state of D-07 returns to normal; if the index after correction is still higher than the threshold value, it is finally confirmed that its state is abnormal, this process embodies the intelligent mechanism of the system to improve the state diagnosis accuracy through dynamic feedback and self-calibration.

[0046] In one specific embodiment, if the expansion risk index deviation value of the cylindrical cell is greater than or equal to the upper limit of the deviation value, and the cylindrical cell numbered D-07 is detected to have reached the upper limit of its expansion risk index deviation value, this indicates that its internal failure risk is extremely high. Within milliseconds, the system will automatically execute the charge / discharge operation to cut off the circuit containing this cell to isolate the risk at its source. Simultaneously, it will initiate forced cooling measures (such as maximizing liquid cooling flow or starting a backup fan) for emergency heat dissipation and send the highest-level alarm information to the monitoring center, accurately identifying the location of the faulty cell and key data. After completing these primary safety responses, the system will continuously record and archive all operational data before and after the fault, forming a record that provides crucial evidence for subsequent root cause analysis and system optimization. This automated emergency mechanism aims to minimize the spread of faults in a single cell, thereby ensuring the safety of the entire battery system.

[0047] The expansion risk index of each cylindrical cell is used to quantify the degree of expansion risk of each cylindrical cell during the charging and discharging process.

[0048] The aforementioned expansion risk threshold refers to the maximum allowable boundary value for cylindrical cells preset in the monitoring database;

[0049] The aforementioned deviation value of the expansion risk index of the cylindrical battery cell refers to the difference between the expansion risk index of the cylindrical battery cell and the expansion risk threshold.

[0050] The aforementioned upper limit of deviation value refers to the upper limit of the preset deviation value of the expansion risk index in the monitoring data.

[0051] Furthermore, the abnormal conditions existing in the cylindrical battery cell are analyzed. The specific analysis process is as follows: the above-mentioned abnormal conditions include operational expansion abnormal conditions and elastic expansion abnormal conditions; if the rate of change of the expansion extrusion pressure of the cylindrical battery cell is greater than the critical upper limit of the rate of change of the expansion extrusion pressure, or if the pressure fluctuation frequency at the slot position of the cylindrical battery cell is greater than the critical upper limit of the pressure fluctuation frequency, then the abnormal condition existing in the cylindrical battery cell is analyzed as an operational expansion abnormal condition; if the charge transfer impedance of the cylindrical battery cell minus the reference impedance is greater than the reference impedance and the charge transfer impedance of the cylindrical battery cell continues to increase, then the abnormal condition existing in the cylindrical battery cell is analyzed as an elastic expansion abnormal condition.

[0052] It needs to be explained that the abnormal expansion condition refers to a proactive and acute failure state of the cylindrical battery cell. This is determined by directly monitoring a severely excessive level of expansion-related physical quantities, specifically, the rate of change of expansion force or the frequency of pressure fluctuations exceeding safety thresholds. This typically indicates a violent side reaction or instantaneous malfunction occurring within the cell, causing its volume to expand abnormally and rapidly, posing an extremely high risk of thermal runaway. This condition represents an ongoing safety event requiring immediate attention.

[0053] Need to explain, elastic expansion abnormal condition, refers to the inherent health status of the cylindrical battery has deteriorated fundamentally, resulting in its response to normal volume change or elastic recovery ability significantly reduced. Its core is the charge transfer impedance appears a substantial and sustained growth. This reflects the serious degradation of the electrochemical interface, so that the battery becomes more fragile, more likely to occur irreversible thickness accumulation and side reactions. The condition represents a potential, cumulative failure risk, indicating that the battery has not immediately dangerous, but its "physical" has been severely decreased, anti-interference ability is weak, is an important precursor of abnormal running expansion.

[0054] Specifically, to determine whether the cylindrical battery is reversible expansion, the specific determination process is: if the analysis result of a certain cylindrical battery is normal, it is determined that the cylindrical battery is reversible expansion; if the analysis result of a certain cylindrical battery is abnormal and there is no abnormal condition, it is determined that the cylindrical battery is reversible expansion, and the monitoring device at the slot position of the cylindrical battery is marked as an over-limit monitoring device, and the over-limit duration of the over-limit monitoring device is recorded; if the analysis result of a certain cylindrical battery is abnormal and there is an abnormal condition, it is determined that the cylindrical battery is irreversible expansion, and the cylindrical battery is subjected to thermal runaway warning.

[0055] In a specific embodiment, the system continuously monitors and analyzes the cylindrical battery numbered D-07. When the monitoring data indicates that the expansion force of the battery temporarily exceeds the conventional range but other parameters (no accompanying abnormalities are seen, the analysis result of the system may determine that it is "normal" or although "abnormal" but no explicit "abnormal condition" (such as internal short circuit, material degradation characteristic signal) is identified. At this time, the system will determine that the current state of D-07 battery is reversible expansion, considering that this expansion is likely to be a temporary phenomenon caused by normal lithium ion intercalation / deintercalation or temporary temperature fluctuations during charging and discharging. Immediately, the system will mark the pressure monitoring device installed at the slot position of the D-07 battery as an "over-limit monitoring device", and start continuously recording the over-limit duration of the device to monitor whether this abnormal state will subside. Conversely, in another scenario, if the analysis result of the battery D-07 is not only "abnormal", but further identifies an explicit "abnormal condition", for example, the charge transfer impedance is monitored to increase sharply and the expansion force continues to rise, which indicates irreversible damage to the internal structure. In this case, the system will unhesitatingly determine that D-07 battery is irreversible expansion, and immediately trigger the thermal runaway warning program for the battery, and start the corresponding safety measures.

[0056] Specifically, the cylindrical battery cell is warned of thermal runaway, and the specific warning process is: if it is determined that a certain cylindrical battery cell is irreversible expansion, the abnormal conditions analyzed by the cylindrical battery cell are obtained; if the cylindrical battery cell has an operating expansion abnormal condition, the cylindrical battery cell is warned of operating abnormal thermal runaway, and the charging and discharging current of the cylindrical battery cell is immediately reduced or cut off, and the thermal management measures of the cylindrical battery cell and the adjacent cylindrical battery cell are started; if the cylindrical battery cell has an elastic expansion abnormal condition, the cylindrical battery cell group is warned of performance abnormal thermal runaway, and the charging and discharging current of the cylindrical battery cell is immediately cut off, and the performance self-checking management measure of the cylindrical battery cell group is started.

[0057] It needs to be explained that reversible expansion refers to the overall expansion phenomenon caused by the periodic and slight volume change of the electrode material lattice due to the embedding and extraction of lithium ions in the electrode material during the normal charging and discharging cycle of the cylindrical battery cell. This expansion is temporary and recoverable, and the expansion force will weaken or disappear when the battery cell is at rest or in a small current state. Its essence is a physical accompanying phenomenon of electrochemical reaction, which generally does not directly threaten the structural integrity and safety of the battery cell, so the system usually regards it as a normal fluctuation range and does not trigger high-level alarms.

[0058] It needs to be explained that irreversible expansion refers to irreversible side reactions or damage occurring inside the cylindrical battery cell, resulting in persistent and cumulative increase in the volume of the battery cell. This expansion is permanent and cannot be restored to its original state even after stopping charging and discharging. It marks the appearance of substantial decay or failure inside the battery cell and is an important precursor to thermal runaway risk. If a certain battery cell is determined to be irreversible expansion, the above warning and intervention process will be immediately started, and targeted safety measures will be taken according to the specific abnormal condition type.

[0059] In a specific embodiment, the cylindrical battery cell is warned of operating abnormal thermal runaway. When it is determined that the cylindrical battery cell numbered D-07 is irreversible expansion and it is analyzed to meet the "operating expansion abnormal condition" (such as monitoring the instantaneous surge of its charging and discharging current accompanied by a sharp rise in temperature), the system will immediately execute a set of combined measures: first, a "operating abnormal thermal runaway warning" of the highest priority is sent to the monitoring center and the on-site operator, and the warning information will clearly point to the D-07 cylindrical battery cell and mark the abnormal type as acute operating failure; At the same time, the charging and discharging current to the D-07 cylindrical battery cell is immediately reduced or cut off to reduce heat generation from the source, and strong thermal management measures for the D-07 cylindrical battery cell and its adjacent cylindrical battery cells are started, such as starting the maximum flow of the liquid cooling system directed to the region or starting the standby fan for directional strong wind cooling, aiming to quickly cool the heat accumulation area and prevent the spread of thermal runaway phenomenon, with the goal of quickly controlling the situation and isolating the risk in the smallest range.

[0060] In a specific embodiment, the performance abnormal thermal runaway early warning is performed on the cylindrical cell group, when it is determined that the cylindrical cell numbered D-07 is irreversible expansion, and it is analyzed that the elastic expansion abnormal condition is met (for example, the charge transfer impedance is significantly increased, and the temperature does not see a sharp fluctuation), at this time, the system triggers another set of response logic: it will issue a performance abnormal thermal runaway early warning to the entire cylindrical cell group, this early warning is more focused on prompting the systematic performance degradation and potential overall risk, rather than the immediate explosion danger; as the core physical intervention, the system will immediately and completely cut off the charge-discharge loop of the D-07 cell, and isolate it from the circuit, so as to avoid the influence of the "short board" cell on the performance and safety of the overall group string; then, the system will start the performance self-check management measures of the cell group, for example, a round of comprehensive voltage, internal resistance and capacity consistency scanning is performed on all cells in the group, so as to evaluate whether the degradation of the D-07 cell has affected the neighbors, and identify whether there are other similar potential fault points in the group. The purpose of this process is to perform preventive diagnosis and maintenance, by identifying and isolating the performance degradation units in advance, to ensure the long-term reliable operation and service life of the battery group.

[0061] Referring to Figure 4 As shown, first, it is judged whether the number of over-limit devices reaches the safety limit value. If it exceeds the safety limit value, a thermal risk early warning is directly triggered; if it does not exceed the safety limit value, the distribution of each over-limit monitoring device is further analyzed, and whether early warning is needed is determined according to the preset thermal risk early warning condition. After it is determined that early warning is needed, the system will make a hierarchical decision according to the risk influence range: when the risk is global, a global thermal risk early warning is triggered and the corresponding level of risk reduction measures is started; when the risk is local, a local thermal risk early warning is triggered and a targeted local disposal scheme is executed, so as to realize the accurate identification, hierarchical early warning and hierarchical prevention and control of the thermal risk.

[0062] Further, the over-limit duration and distribution of each over-limit monitoring device are acquired and analyzed, and the specific analysis process is as follows: the over-limit duration of each over-limit monitoring device refers to the cumulative duration that the expansion extrusion force at the clamping groove position of the cylindrical cell is greater than or equal to the upper limit value of the expansion extrusion force in the monitoring database; the distribution, i.e., the distribution of each over-limit monitoring device, refers to the position information of each over-limit monitoring device with time identifier in the cylindrical cell group.

[0063] It needs to be explained that the position identification of each over-limit monitoring device and the appearance characteristics of the time expression on the spatial dimension and the time dimension of the cylindrical battery cell group. In the preset time period, the signals reported by the multiple over-limit monitoring devices are gathered in the same specific battery cell in space, and present a highly co-occurring or closely related distribution characteristic in time. This characteristic is the key criterion for realizing accurate thermal risk early warning. Through cross verification of multi-sensor information in the time-space dimension, random interference is excluded, confirming that the global anomaly is caused by a single battery cell internal serious fault, thereby locking the local risk area that needs to be immediately warned.

[0064] The number of over-limit monitoring devices whose over-limit duration exceeds the preset critical over-limit duration is counted and marked as the over-limit monitoring device statistical quantity.

[0065] Specifically, based on the analysis result, it is determined whether to perform thermal risk early warning on the cylindrical battery cell. The specific determination process is: if the over-limit monitoring device statistical quantity is greater than or equal to the safety quantity limit value, it is determined to perform thermal risk early warning on the cylindrical battery cell, and thermal risk early warning is performed on the cylindrical battery cell group; if the over-limit monitoring device statistical quantity is less than the safety quantity limit value, the distribution of each over-limit monitoring device is analyzed, and if the distribution of each over-limit monitoring device exists a thermal risk early warning condition, it is determined to perform thermal risk early warning on the cylindrical battery cell, and thermal risk early warning is performed on the risk area of the cylindrical battery cell group; if the distribution of each over-limit monitoring device does not exist a thermal risk early warning condition, it is determined not to perform thermal risk early warning on the cylindrical battery cell.

[0066] The above-mentioned thermal risk early warning condition refers to that in the preset time period, any two or more over-limit monitoring devices point to the same cylindrical battery cell, that is, the cylindrical battery cells monitored by any two or more over-limit monitoring devices are the same, and the cylindrical battery cell group risk area is the cylindrical battery cell and the adjacent cylindrical battery cell.

[0067] The above-mentioned safety quantity limit value refers to the upper limit value of the preset number of over-limit monitoring devices in the monitoring database.

[0068] In a specific embodiment, assuming that the safety quantity limit value preset in the monitoring system of a certain cylindrical battery cell group is 3. When it is monitored that there are 4 over-limit monitoring devices in the module at the same time, since the number of over-limit monitoring devices (4) is greater than or equal to the safety quantity limit value (3), it is determined to perform global thermal risk early warning on the cylindrical battery cell group, and to synchronously issue thermal risk early warning on the entire cylindrical battery cell group. At this time, no matter where these over-limit devices are distributed, it means that the risk has widely existed, and immediate comprehensive emergency response needs to be started, such as reducing the output power of the entire module and starting global cooling.

[0069] In a specific embodiment, if the system detects that there are only 2 monitoring devices (less than the safety number limit of 3) that are out of limit, the system further analyzes the distribution of the monitoring devices. For example, two out-of-limit monitoring devices, T-11 and P-11, are both directed to the same cylindrical battery cell (numbered D-07). Since there are two or more out-of-limit devices directed to the same battery cell, this meets the preset thermal risk warning condition, and the system determines to perform a precise thermal risk warning on the battery cell D-07, and defines the warning range as a "risk area" centered on D-07, i.e., including D-07 itself and all adjacent battery cells. The system then starts local intensive thermal management measures for the specific area and monitors the battery cells in the risk area, thereby realizing intelligent switching from global defense to precise intervention. If the two out-of-limit devices are directed to two different battery cells that are not associated and do not form a cluster in distribution, the system determines that there is no imminent thermal risk and does not issue a warning, but records the abnormal data for trend analysis.

[0070] Specifically, for thermal risk warning of cylindrical battery cells, the specific warning process is as follows: the above determination of thermal risk warning of cylindrical battery cells includes thermal risk warning of a cylindrical battery cell group and thermal risk warning of a risk area of a cylindrical battery cell group; if the number of out-of-limit monitoring devices is greater than or equal to the safety number limit, the cylindrical battery cell group is subjected to thermal risk warning, which triggers a global thermal risk warning and automatically executes a global risk reduction measure; if the number of out-of-limit monitoring devices is less than the safety number limit and the distribution of each out-of-limit monitoring device meets the thermal risk warning condition, the risk area of the cylindrical battery cell group is subjected to thermal risk warning, which triggers a local thermal risk warning and automatically executes a local risk reduction measure.

[0071] In a specific embodiment, a cylindrical battery cell group composed of 24 cylindrical battery cells (numbered A01 to A24) is monitored. When it is determined that the entire cylindrical battery cell group needs to be subjected to thermal risk warning, for example, because multiple monitoring devices that exceed the safety number limit are dispersed in the module, which indicates that the risk is universal. At this time, the warning trigger area obtained is the entire module, and a global thermal risk warning is triggered. After the warning is triggered, the system automatically executes a global risk reduction measure, which specifically includes immediately limiting the total output power of the module to below the safety level, starting all cooling fans or liquid cooling pumps in the module to maximum power for global forced heat dissipation, and simultaneously sending a highest-level alarm to the battery management system and the monitoring center, prompting the need for systematic inspection or maintenance of the entire module. The core is to take unified and comprehensive measures to ensure overall safety.

[0072] In a specific embodiment, the judgment only needs to give a thermal risk warning for the risk area of the cylindrical cell group, for example, because the monitored pressure and temperature sensors are concentrated on the cells A08, A09 and their adjacent cells A07 and A10, the system obtains the warning trigger area as the local area with A08 and A09 as the core, and triggers a local thermal risk warning. The system then automatically performs local risk reduction measures, which are highly targeted: it may only limit the current flowing through the cells A07, A08, A09 and A10, only open specific cooling channels near the area for focused cooling, and highlight the risk area on the monitoring interface to remind the operator to pay attention, effectively controlling the local risk while minimizing the impact on the performance of other normal parts of the module.

[0073] A monitoring database is used to store the parameters of the cylindrical cell slot-adapted expansion extrusion force monitoring method and device.

[0074] It needs to be explained that the monitoring database first enters the calibration parameters of each force sensing card slot and the static information of the cell into the database before testing, establishing a mapping relationship. After the test starts, the extrusion force generated by the cell expansion is captured by the sensor in the card slot in real time, the signal is converted after conditioning and conversion, and the accurate force and temperature values are calculated by the data processing service according to the calibration parameters, and are time-stamped, continuously flowing into the core data table of the database. At the same time, the system synchronizes the voltage, current and other working condition data provided by the battery test equipment, associates them with the mechanical data through time stamping, and records the instantaneous state of the cell completely. The entire process integrates hardware signals, electrical parameters and static metadata into a multi-dimensional data set that is aligned on the timeline and logically associated, ultimately forming an intelligent data platform for battery expansion behavior analysis and safety warning.

[0075] The acquisition of parameters is an automated and multi-step process. First, static parameters such as the unique number, model, rated capacity and other basic information of the battery cell, and the procedure information of the test task are manually entered by the operator through the system interface before the test starts or are imported from the external system into the battery cell information table and the test task table in the database. Second, the acquisition of the most core dynamic parameters, i.e. the squeeze force and temperature, is a real-time cycle. The continuous analog signals generated by the force sensor and the temperature sensor are converted into digital signals by the data acquisition unit, and then read by the main controller. The controller calls the calibration coefficients and temperature compensation algorithms stored in the sensor configuration table to process the raw data and convert them into accurate squeeze force values and temperature values with physical units. These processed data, together with accurate time stamps and corresponding slot position numbers, are packaged and sent to the upper computer software through the communication network, and finally inserted into the real-time monitoring data table in the database in batches and in order. At the same time, the battery voltage, current and other working condition data from the battery test equipment are also collected synchronously to the main controller at a preset sampling frequency. These electrical signal data are also subjected to necessary filtering and calibration processing, and are given high-precision time stamps strictly synchronized with the squeeze force and temperature data by the controller, and are associated with the corresponding battery number. Finally, all the multi-dimensional data from different sources but synchronized in time, including mechanical squeeze force, physical temperature, electrical voltage and current, are integrated into a complete data package and uploaded to the real-time monitoring data table in the database, providing a comprehensive, consistent and time-aligned data basis for subsequent risk index calculation and state analysis.

[0076] The second aspect of the present application provides an expansion squeeze force monitoring device adapted to a cylindrical battery cell slot, comprising: a thermal runaway early warning sensor and a sensor fixing clamp; the thermal runaway early warning sensor is a ultra-thin flexible sensor used for monitoring the expansion squeeze force between the cylindrical battery cell slot position, i.e. between two cylindrical battery cells, by configuring an internal pressure-sensitive function layer resistance to monitor the expansion squeeze force between the cylindrical battery cell slot position, i.e. between two cylindrical battery cells in real time; the integrated monitoring device is a device used for receiving multi-source monitoring data of cylindrical battery, including monitoring data of each thermal runaway early warning sensor and operating state parameters of each cylindrical battery.

[0077] In a specific embodiment, the thermal runaway early warning sensor is embedded in a mounting hole opened at the position of the cylindrical cell clamping groove, i.e. between two cylindrical cells, so that its sensing surface is flush with or slightly protrudes from the outer wall of the cell, thereby directly sensing the radial expansion force generated by the volume change of the cylindrical cell during charging and discharging. The real-time pressure data collected by the thermal runaway early warning sensor is transmitted to the integrated monitoring device through a dedicated line, and at the same time, the device also synchronously acquires the charge transfer impedance, temperature and voltage of each cell from the battery management system through the CAN bus. The integrated monitoring device performs multi-source information fusion analysis on the received pressure data and electrochemical parameters. For example, when the rate of change of the expansion force of a certain cell exceeds the threshold value, and at the same time, its charge transfer impedance shows abnormal fluctuations, it is determined that the cell has a risk of thermal runaway, and a graded early warning signal is immediately generated and uploaded to the battery management system, thereby realizing real-time monitoring and active protection of the safety state of all cylindrical cells in the module.

[0078] In a specific embodiment, the installation of the thermal runaway early warning sensor is achieved by inserting a set of sensor fixing blocks at the position of the cylindrical cell clamping groove, i.e. between two cylindrical cells. The sensor fixing blocks are provided with an inner concave circular arc surface matching the curvature of the cell outer wall. By splicing a set of sensor fixing blocks in opposite directions along the radial direction of the cell, the inner concave circular arc surface is tightly wrapped and fixed to the outer wall of the cylindrical cell, thereby stably fixing the thermal runaway early warning sensor at the preset monitoring position. The sensor senses the radial extrusion force generated during the expansion of the cell through its built-in pressure-sensitive functional layer, and the collected pressure data is transmitted to the integrated monitoring device through a dedicated line. At the same time, the device also synchronously acquires the charge transfer impedance, temperature and voltage of each cell from the battery management system through the CAN bus. The integrated monitoring device performs multi-source information fusion analysis on the received pressure data and electrochemical parameters. For example, when the expansion force of a certain cell rises sharply within a short period of time, and at the same time, its charge transfer impedance shows abnormal fluctuations, it is determined that the cell has a risk of thermal runaway, and a graded early warning signal is immediately generated and uploaded to the battery management system, thereby realizing real-time monitoring and active protection of the safety state of the cylindrical cell without damaging the structure of the cell. The sensor fixing block refers to the inner concave circular arc clamping groove used to fix the thermal runaway early warning sensor. By splicing a pair of sensor fixing blocks in opposite directions along the radial direction of the cell, the inner concave circular arc surface is tightly wrapped and fixed to the outer wall of the cylindrical cell, thereby fixing the thermal runaway early warning sensor at the clamping groove adaptation position of the cylindrical cell.

[0079] The above content is only an example and description of the structure of the present application. Those skilled in the art can make various modifications or supplements or use similar ways to replace the described specific embodiments without deviating from the structure of the present application or exceeding the scope defined by the present application.

Claims

1. A method for monitoring expansion and compression pressure based on cylindrical cell slot adaptation, characterized in that, include: S1. Mark each expansion and extrusion pressure monitoring device deployed at each cylindrical cell slot as a monitoring device. Each monitoring device monitors the expansion and extrusion pressure and real-time temperature at each cylindrical cell slot in real time. The real-time temperature is used to compensate for the expansion and extrusion pressure monitored by each monitoring device at each cylindrical cell slot to obtain the temperature compensation pressure, and the temperature compensation parameters of each monitoring device are initialized. S2. If a monitoring device monitors the expansion pressure at the slot of a cylindrical battery cell in real time and it is greater than or equal to the upper limit of the expansion pressure preset in the monitoring database, the device identifies and analyzes the operating status of each cylindrical battery cell monitored by the monitoring device. Based on the analysis results of the operating status of a cylindrical battery cell, the device determines whether the cylindrical battery cell is undergoing reversible expansion. If the cylindrical battery cell is determined to be undergoing reversible expansion, the monitoring device at the slot of the cylindrical battery cell is marked as an over-limit monitoring device, and the over-limit duration of the over-limit monitoring device is recorded. If the cylindrical battery cell is determined to be undergoing reversible expansion, a thermal runaway warning is issued for the cylindrical battery cell. S3. Obtain and analyze the over-limit duration and distribution of each over-limit monitoring device, and determine whether to issue a thermal risk warning for the cylindrical battery cell based on the analysis results.

2. The expansion and compression pressure monitoring method based on cylindrical cell slot adaptation according to claim 1, characterized in that: The initialization process for the temperature compensation parameters of each monitoring device is as follows: The temperature compensation pressure is obtained by real-time monitoring of the expansion and extrusion pressure at the slot of each cylindrical cell by each monitoring device. The real-time temperature of each cylindrical cell is obtained from the monitoring devices, and the temperature is input into the preset temperature-compensated drift compensation mapping table in the monitoring database. The real-time temperature-compensated drift compensation pressure of each monitoring device is mapped and output. The temperature compensation parameters of each monitoring device are initialized by compensating the real-time temperature compensation drift pressure of each monitoring device. The temperature-compensated pressure refers to the expansion and compression pressure after compensation by each monitoring device based on real-time temperature. The temperature compensation parameters of each monitoring device refer to the compensation data on the relationship between the expansion and compression output values ​​of each monitoring device and temperature changes.

3. The expansion and compression pressure monitoring method based on cylindrical cell slot adaptation according to claim 1, characterized in that: The specific analysis process for identifying and analyzing the operating status of each cylindrical battery cell monitored by the monitoring device is as follows: The operating status parameters of each cylindrical battery cell monitored by the monitoring device are obtained. The operating parameters of each cylindrical cell include the rate of change of expansion and extrusion pressure of each cylindrical cell, the frequency of pressure fluctuation at the slot of each cylindrical cell, and the charge transfer impedance of each cylindrical cell. By introducing weighted contribution coefficients, the coupling factors between the rate of change of expansion extrusion pressure of each cylindrical cell and the pressure fluctuation frequency at the slot position of each cylindrical cell, as well as the contribution of the charge transfer impedance factor of each cylindrical cell to the expansion risk index of each cylindrical cell, are quantified respectively. The expansion risk index of each cylindrical cell is obtained by coupling the contribution factors. The expansion risk index of each cylindrical cell is compared with the expansion risk threshold. If the expansion risk index of a cylindrical battery cell is less than the expansion risk threshold, then the cylindrical battery cell is in normal operating condition. If the expansion risk index of a cylindrical cell is greater than or equal to the expansion risk threshold, then the deviation value of the expansion risk index of the cylindrical cell is obtained, and the expansion risk deviation value of the cylindrical cell is compared with the upper limit of the deviation value. If the deviation value of the expansion risk index of the cylindrical battery cell is greater than or equal to the upper limit of the deviation value, then the operating state of the cylindrical battery cell is abnormal. Analyze the abnormal conditions existing in the cylindrical battery cell. If the deviation value of the expansion risk index of the cylindrical cell is less than the upper limit of the deviation value, the temperature compensation coefficient of each monitoring device of the cylindrical cell is corrected by the expansion risk index of the cylindrical cell. The expansion risk index of the cylindrical cell after correction is obtained and compared with the expansion risk threshold. If the expansion risk index of the cylindrical cell after correction is less than the expansion risk threshold, the operating status of the cylindrical cell is normal. If the expansion risk index of the cylindrical cell after correction is greater than the expansion risk threshold, then the operating status of the cylindrical cell is abnormal. The expansion risk index of each cylindrical cell is used to quantify the degree of expansion risk of each cylindrical cell during the charging and discharging process. The expansion risk threshold refers to the maximum allowable boundary value of cylindrical cells preset in the monitoring database; The deviation value of the expansion risk index of the cylindrical battery cell refers to the difference between the expansion risk index of the cylindrical battery cell and the expansion risk threshold. The upper limit of the deviation value refers to the upper limit of the preset deviation value of the expansion risk index in the monitoring data.

4. The expansion and compression pressure monitoring method based on cylindrical cell slot adaptation according to claim 3, characterized in that: The analysis of the abnormal conditions existing in the cylindrical battery cell is as follows: The abnormal conditions include both operational expansion abnormal conditions and elastic expansion abnormal conditions. If the rate of change of the expansion and extrusion pressure of the cylindrical battery cell is greater than the critical upper limit of the rate of change of the expansion and extrusion pressure, or if the pressure fluctuation frequency at the slot of the cylindrical battery cell is greater than the critical upper limit of the pressure fluctuation frequency, then the abnormal condition existing in the cylindrical battery cell is analyzed as an abnormal condition of operational expansion. If the charge transfer impedance of the cylindrical cell minus the reference impedance is greater than the reference impedance and the charge transfer impedance of the cylindrical cell continues to increase, then the abnormal condition existing in the cylindrical cell is analyzed to be an abnormal condition of elastic expansion.

5. The expansion and compression pressure monitoring method based on cylindrical cell slot adaptation according to claim 1, characterized in that: The specific process for determining whether the cylindrical battery cell exhibits reversible expansion is as follows: If the analysis result of a cylindrical battery cell is normal, then the cylindrical battery cell is determined to have reversible expansion. If the analysis result of a cylindrical battery cell is abnormal and there are no abnormal conditions, the cylindrical battery cell is determined to be reversibly expanded. The monitoring device at the slot of the cylindrical battery cell is marked as an over-limit monitoring device, and the over-limit duration of the over-limit monitoring device is recorded. If the analysis results of a cylindrical battery cell are abnormal and abnormal conditions exist, the cylindrical battery cell is determined to be undergoing irreversible expansion, and a thermal runaway warning is issued for the cylindrical battery cell.

6. The expansion and compression pressure monitoring method based on cylindrical cell slot adaptation according to claim 5, characterized in that: The thermal runaway early warning system for the cylindrical battery cell is specifically implemented as follows: If a cylindrical battery cell is determined to be undergoing irreversible expansion, then the abnormal conditions analyzed for that cylindrical battery cell are obtained. If the cylindrical cell has abnormal expansion conditions during operation, an early warning of abnormal thermal runaway will be issued for the cylindrical cell, and the charging and discharging current of the cylindrical cell will be reduced immediately, and thermal management measures for the cylindrical cell and adjacent cylindrical cells will be initiated. If the cylindrical cell exhibits abnormal elastic expansion, an early warning for thermal runaway of the cylindrical cell assembly will be issued, and the charging and discharging of the cylindrical cell will be immediately cut off, initiating performance self-check management measures for the cylindrical cell assembly.

7. The expansion and compression pressure monitoring method based on cylindrical cell slot adaptation according to claim 1, characterized in that: The specific analysis process for acquiring and analyzing the over-limit duration and distribution of each over-limit monitoring device is as follows: The over-limit duration of each over-limit monitoring device refers to the cumulative duration during which the expansion and extrusion pressure at the location of the cylindrical cell slot is greater than or equal to the upper limit value of the preset expansion and extrusion pressure in the monitoring database. The distribution situation, namely the distribution of each over-limit monitoring device, refers to the location information of each over-limit monitoring device with time stamp in the cylindrical cell group; The number of over-limit monitoring devices whose over-limit duration exceeds the preset critical over-limit duration is counted and marked as the number of over-limit monitoring devices.

8. The expansion and compression pressure monitoring method based on cylindrical cell slot adaptation according to claim 7, characterized in that: The specific determination process for whether to issue a thermal risk warning for cylindrical battery cells based on the analysis results is as follows: If the number of cells detected by the over-limit monitoring device is greater than or equal to the safe quantity limit, then a thermal risk warning is issued for the cylindrical cells. If the number of over-limit monitoring devices is less than the safe quantity limit, the distribution of each over-limit monitoring device is analyzed. If the distribution of each over-limit monitoring device presents a thermal risk warning condition, then a thermal risk warning is issued for the cylindrical battery cell. If the distribution of each over-limit monitoring device does not meet the conditions for thermal risk warning, then it is determined that thermal risk warning will not be issued for the cylindrical battery cells. The aforementioned thermal risk warning condition refers to the presence of any two or more over-limit monitoring devices pointing to the same cylindrical cell within a preset time period, i.e., any two or more over-limit monitoring devices monitoring the same cylindrical cell. The risk area of ​​the cylindrical cell group is the cylindrical cell and the adjacent cylindrical cells.

9. The expansion and compression pressure monitoring method based on cylindrical cell slot adaptation according to claim 1, characterized in that: The specific process for thermal risk warning of cylindrical battery cells is as follows: The determination to provide thermal risk warning for cylindrical cells includes providing thermal risk warning for cylindrical cell groups and providing thermal risk warning for risk areas of cylindrical cell groups. If the number of cells detected by the over-limit monitoring device is greater than or equal to the safe quantity limit, a thermal risk warning will be issued for the cylindrical battery pack, triggering a global thermal risk warning and automatically implementing global risk reduction measures. If the number of over-limit monitoring devices is less than the safe quantity limit and the distribution of each over-limit monitoring device presents a thermal risk warning condition, then a thermal risk warning will be issued for the risk area of ​​the cylindrical battery cell group, triggering a local thermal risk warning and automatically implementing local risk reduction measures.

10. An expansion and extrusion pressure monitoring device based on a cylindrical battery cell slot, employing the expansion and extrusion pressure monitoring method based on a cylindrical battery cell slot as described in any one of claims 1-9, characterized in that: include: Thermal runaway early warning sensor and integrated monitoring device; The thermal runaway early warning sensor refers to an ultra-thin flexible sensor used to monitor the expansion and extrusion force between two cylindrical cells at the cylindrical cell slot location. It monitors the expansion and extrusion force between two cylindrical cells in real time through the configured internal pressure-sensitive functional layer resistor. The integrated monitoring device refers to a device used to receive multi-source monitoring data from cylindrical batteries. The multi-source monitoring data includes monitoring data from each thermal runaway early warning sensor and operating status parameters of each cylindrical battery cell.

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