Thermal runaway early warning method and system based on sodium ion battery module

Abstract

The invention discloses a thermal runaway early warning method and system based on a sodium ion battery module, the sodium ion battery module comprises a plurality of sodium ion batteries, the early warning method comprises the following steps: selecting at least two pressure detection positions in the sodium ion battery module, the pressure detection positions being arranged on the surfaces of different sodium ion batteries; synchronously acquiring pressure values of at least two pressure detection positions, and constructing a dynamic pressure curve; acquiring a pressure difference value of any two pressure detection positions at the same time point based on the dynamic pressure curve; if the pressure difference value is larger than a pressure difference threshold value, an early warning signal is sent out. According to the method, the pressure detection positions are arranged on the surfaces of different sodium ion batteries, the thermal runaway condition of the battery module is judged by comparing the pressure difference between any two pressure detection positions with the pressure difference threshold value, the running state of the whole battery module can be reflected on the whole, and the early warning accuracy is improved.

Description

Technical Field

[0001] The present invention belongs to the field of battery technology, and in particular relates to a thermal runaway early warning method and system based on a sodium ion battery module. Background Art

[0002] Sodium-ion batteries, a promising energy storage device, are attracting increasing attention for their safety. Thermal runaway is a serious safety risk faced by sodium-ion batteries. Once it occurs, it can lead to dangerous situations such as battery fire and explosion, resulting in significant losses to personnel and property.

[0003] The current energy storage industry generally uses monitoring methods based on temperature and voltage parameters as the primary basis for battery safety warnings, but this traditional method suffers from significant lag. Temperature monitoring is typically set at 60°C as the warning threshold. This is because when the internal battery temperature reaches this critical point, the positive electrode material begins to decompose and the electrolyte enters a rapid evaporation phase. However, before the temperature reaches 60°C, the battery undergoes complex chemical reactions. Voltage monitoring also suffers from similar shortcomings. When a sudden voltage drop is detected, it indicates a severe short circuit or localized thermal runaway within the battery. At this point, the battery temperature often exceeds 80°C, and thermal runaway enters an irreversible accelerated phase. More critically, in large-scale energy storage systems, due to the thermal inertia of battery modules and temperature transmission delays, surface temperature monitoring often lags behind actual internal temperature changes. Voltage parameters also take even longer to respond to early failures.

[0004] This double lag effect results in a time lag window in the existing early warning system, making it impossible to identify thermal runaway precursor signals at an early stage, and the early warning is poor in comprehensiveness and accuracy. Summary of the Invention

[0005] The purpose of the present invention is to enable a sodium ion battery to send out a warning signal in time before thermal runaway occurs, so as to improve the accuracy of the sodium ion battery module in the warning process.

[0006] To achieve the above objectives, the present invention proposes a thermal runaway early warning method based on a sodium-ion battery module, wherein the sodium-ion battery module includes multiple sodium-ion batteries. The early warning method comprises: selecting at least two pressure detection locations in the sodium-ion battery module, wherein the pressure detection locations are located on the surfaces of different sodium-ion batteries; synchronously obtaining pressure values ​​at the at least two pressure detection locations to construct a dynamic pressure curve; based on the dynamic pressure curve, obtaining a pressure difference between any two pressure detection locations at the same time point; and issuing an early warning signal if the pressure difference is greater than a pressure difference threshold.

[0007] In an optional embodiment, the thermal runaway warning method based on the sodium-ion battery module further includes: based on the same time point, comparing the pressure value of any of the pressure detection positions with the pressure threshold, and if any of the pressure values ​​is greater than the pressure threshold, issuing a first-level warning signal.

[0008] In an optional embodiment, the pressure threshold ranges from 1.8 MPa to 2.2 MPa.

[0009] In an optional embodiment, the thermal runaway warning method based on the sodium-ion battery module further includes: based on the dynamic pressure curve, obtaining the pressure change rate of each of the pressure detection positions in the same time period; before or after issuing the first-level warning signal, comparing the pressure change rate with the rate change threshold, and if the pressure change rate is greater than the rate change threshold, issuing a second-level warning signal.

[0010] In an optional embodiment, the rate change threshold range is 0.05 MPa / min to 0.15 MPa / min.

[0011] In an optional embodiment, the warning signal is a third-level warning signal, which is issued before the first-level warning signal or after the second-level warning signal; or the third-level warning signal, the second-level warning signal and the first-level warning signal are issued simultaneously.

[0012] In an optional embodiment, the pressure difference threshold ranges from 0.9 MPa to 1.1 MPa.

[0013] The present invention also proposes a thermal runaway early warning system based on a sodium ion battery module, comprising: a pressure collector, arranged at at least two pressure detection positions of the sodium ion battery module, wherein the pressure detection positions are arranged on the surface of the sodium ion batteries of the sodium ion battery module, and the pressure collector is suitable for collecting the pressure values ​​of the pressure detection positions; a data collector, communicatively connected to the pressure collector, to synchronously obtain the pressure values ​​of the at least two pressure detection positions; a data processing module, communicatively connected to the data collector, to construct a dynamic pressure curve based on the pressure values ​​of the at least two pressure detection positions, and based on the dynamic pressure curve, obtain the pressure difference between any two pressure detection positions at the same time point, and if the pressure difference is greater than a pressure difference threshold, a warning signal is issued.

[0014] In an optional embodiment, the at least two pressure detection positions are spaced apart from each other and are evenly distributed on the sodium ion battery module.

[0015] In an optional embodiment, the sodium ion battery module includes thirteen sodium ion batteries, wherein the middle of the surface of the fourth sodium ion battery and the middle of the surface of the tenth sodium ion battery are both provided with pressure detection positions.

[0016] The beneficial effects of the present invention are:

[0017] 1. Through a reasonable layout, the present invention sets pressure detection positions on the surface of different sodium-ion batteries. The thermal runaway of the battery module is judged by comparing the pressure difference between any two pressure detection positions with the pressure difference threshold. This can reflect the operating status of the entire battery module as a whole and improve the accuracy of the early warning.

[0018] 2. By constructing a dynamic pressure curve based on multiple pressure detection locations, the pressure changes in the battery module can be monitored from multiple angles. Compared with the method of setting pressure detection points only on the surface of a single battery cell or a local area of ​​the battery module, this method can more comprehensively reflect the operating status of the entire battery module, effectively avoiding the missed reporting of thermal runaway due to the failure to timely monitor local pressure changes, and improving the comprehensiveness and accuracy of early warning.

[0019] 3. The present invention can more accurately and comprehensively reflect the severity of thermal runaway through the hierarchical mechanism of the first-level warning signal, the second-level warning signal and the third-level warning signal, and can provide a basis for taking different countermeasures. Among them, the first-level warning serves as basic monitoring and provides continuous status feedback; after the first-level warning, the second-level warning is issued according to the pressure change rate, which realizes the attention to the dynamic changes of pressure in the second-level warning stage and improves the timeliness of the warning; and the third-level warning, based on the second-level warning, can focus on local anomalies in order to enhance spatial resolution. There is a strict logical relationship between these three warning levels. This hierarchical design not only improves the accuracy of the warning, but also realizes the refinement of the warning information. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Flowchart of a thermal runaway early warning method based on a sodium-ion battery module provided for the implementation of the present invention;

[0021] Figure 2 A flowchart between three warning levels of a thermal runaway warning method for sodium-ion battery modules provided for implementation of the present invention;

[0022] Figure 3 A pressure curve diagram of the thermal runaway early warning method based on a sodium-ion battery module provided by the present invention;

[0023] Figure 4 A block diagram of a thermal runaway warning system based on a sodium-ion battery module provided in an embodiment of the present invention;

[0024] Figure 5 Schematic diagram of the layout of the pressure collector of the thermal runaway warning system based on the sodium ion battery module provided in an embodiment of the present invention.

[0025] Description of reference numerals:

[0026] 110. Pressure collector. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1 and Figure 3 As shown, according to an embodiment of the present invention, on the one hand, a thermal runaway early warning method based on a sodium ion battery module is provided, comprising the following steps:

[0029] Step S101: selecting at least two pressure detection positions in a sodium ion battery module, where the pressure detection positions are located on surfaces of different sodium ion batteries;

[0030] Step S103: synchronously acquiring pressure values ​​of at least two pressure detection positions and constructing a dynamic pressure curve;

[0031] Step S105: Based on the dynamic pressure curve, the pressure difference between any two pressure detection positions at the same time point is obtained.

[0032] Step S107: If the pressure difference is greater than the pressure difference threshold, a warning signal is issued.

[0033] In this embodiment, the sodium-ion battery module is typically composed of multiple closely packed sodium-ion batteries, which may have different internal layouts and operating conditions. Therefore, selecting pressure detection locations on different sodium-ion battery surfaces can more accurately reflect pressure changes within the entire module. Pressure, in turn, represents internal stress, helping to promptly detect potential thermal runaway events. By simultaneously monitoring pressure changes at at least two locations, we can better understand the spread of thermal runaway within the battery module.

[0034] Compared to traditional temperature and voltage monitoring, pressure testing can detect subtle changes in battery materials at the early stages of thermal runaway, changes that often occur before temperature rise or voltage fluctuations. When an abnormality begins to occur inside the battery, the expansion and contraction of the electrode material is immediately reflected in the pressure change. This mechanical response is almost instantaneous and unaffected by thermal conduction delays. Another significant advantage of pressure testing is its ability to fully reflect the internal state of the battery. It not only captures local anomalies but also reveals the health of the entire battery module through changes in pressure distribution. This global perspective cannot be provided by a single temperature or voltage monitoring point. In addition, pressure testing has excellent anti-interference capabilities and is less affected by ambient temperature fluctuations or electrical noise, ensuring the reliability of the monitoring results.

[0035] In this embodiment, based on the simultaneous time attribute, the pressure values ​​of each pressure detection position are synchronously obtained, and the difference between these pressure values ​​is calculated. The pressure difference refers to the difference in pressure values ​​between different pressure detection positions, which is usually expressed by the formula: pressure difference = |P1-P2|, where P1 and P2 are the pressure values ​​of two different pressure detection positions. The difference threshold is set according to the pressure change law of the sodium-ion battery under normal working conditions and the possible thermal runaway pressure change law. The difference threshold can be dynamically adjusted according to the actual use of the battery and environmental conditions to adapt to the pressure changes under different working conditions.

[0036] The calculated pressure difference is compared with a preset difference threshold. If the pressure difference exceeds the preset difference threshold at a certain point in time or within a period of time, an early warning signal is issued, usually indicating that the risk of thermal runaway is high and emergency measures need to be taken immediately.

[0037] The pressure difference threshold ranges from 0.9MPa to 1.1MPa, preferably 1MPa. The determination of this threshold has been rigorously verified by experiments, taking into full account the pressure distribution characteristics of the sodium-ion battery module under different operating conditions. This early warning condition is specifically designed for local thermal runaway situations. By comparing the pressure measurements at at least two sodium-ion batteries in real time, the system can keenly capture abnormal pressure distribution inside the module. When a pressure difference exceeding 1MPa is detected, it indicates that a significant pressure gradient has appeared inside the battery module. This uneven pressure distribution often indicates that an abnormality is occurring in a local area, such as a short circuit inside a single cell, local failure of the electrode material, or uneven distribution of the electrolyte.

[0038] Furthermore, the thermal runaway early warning method based on the sodium ion battery module also includes the following steps:

[0039] Step S109: Based on the same time point, the pressure value of any pressure detection position is compared with the pressure threshold. If any pressure value is greater than the pressure threshold, a first-level warning signal is issued.

[0040] The simultaneous temporal attribute includes a specific time point and time period. At the same time point, pressure values ​​at each pressure detection location are acquired simultaneously, and each pressure value is compared with a preset pressure threshold. The pressure threshold is set based on the pressure range of the sodium-ion battery under normal operating conditions and the pressure variation patterns that may occur during thermal runaway. Typically, the pressure threshold is dynamically adjusted based on the battery's initial state and actual usage. For example, the performance of sodium-ion batteries gradually changes due to factors such as the number of charge and discharge cycles, ambient temperature fluctuations, and usage duration. Therefore, dynamic adjustment of the threshold can improve the accuracy of early warnings. The core of the first-level warning mechanism is real-time monitoring of pressure values. If the pressure value at any pressure detection location exceeds the preset pressure threshold at a specific time point or time period, a first-level warning signal is issued. A first-level warning signal indicates a potential risk of thermal runaway, requiring further monitoring and action. Synchronously acquiring pressure data and making early warning decisions based on pressure values ​​with simultaneous temporal attributes can promptly detect early signs of thermal runaway, buying valuable time for action.

[0041] Furthermore, the pressure threshold ranges from 1.8MPa to 2.2MPa. It can be preferably 2MPa. The establishment of this value is based on the statistical analysis of experimental data, fully considering the combined influence of different factors. When the monitored pressure value exceeds this threshold, it indicates that obvious material expansion and structural deformation have begun to occur inside the battery. This mechanical response usually originates from the lattice change of the electrode material during the sodium ion insertion / extraction process. It may also indicate that a more serious thermal runaway risk is brewing. It is worth noting that the pressure change at this stage has a dual meaning: on the one hand, it may be the periodic pressure fluctuation generated by the battery during the normal charge and discharge cycle, especially in high-rate charge and discharge or low-temperature environments. Such pressure fluctuations may temporarily exceed the 2MPa threshold; on the other hand, it may also be an early sign of thermal runaway, such as the beginning of SEI film decomposition, side reactions in the electrolyte, etc., which will lead to an abnormal increase in pressure values. In order to accurately distinguish between these two situations, it is necessary to combine the historical trend of pressure changes, charge and discharge status, and ambient temperature and other multi-dimensional information for comprehensive judgment. When the pressure value continues to exceed the threshold and shows an upward trend, the system will automatically increase the monitoring frequency and start more detailed data recording to provide a basis for subsequent early warning upgrades.

[0042] Furthermore, the thermal runaway early warning method based on the sodium ion battery module also includes the following steps:

[0043] Step S1011: based on the dynamic pressure curve, obtaining the pressure change rate of each pressure detection position within the same time period;

[0044] Step S1013: Before or after issuing the first-level warning signal, compare the pressure change rate with the rate change threshold. If the pressure change rate is greater than the rate change threshold, issue a second-level warning signal.

[0045] In this embodiment, the pressure change rate of each pressure detection position is calculated by synchronously acquiring the pressure data. The pressure change rate refers to the amount of change in the pressure value per unit time, which is usually expressed as:

[0046] Among them, ΔP is the change in pressure value, and ΔT is the change in time.

[0047] The rate change threshold is set based on the pressure change pattern of sodium-ion batteries under normal operating conditions and the pressure change pattern that may occur during thermal runaway. The calculated pressure change rate is compared with the preset rate change threshold. If the pressure value at any pressure detection location exceeds the preset pressure threshold at a certain time point or time period, a level 1 warning signal is issued. If the pressure change rate at any pressure detection location exceeds the preset rate change threshold at a certain time point or time period, a level 2 warning signal is issued.

[0048] When the pressure change rate exceeds the rate threshold, it indicates rapid mechanical stress accumulation within the battery. This dynamic characteristic often indicates the accelerating risk of thermal runaway. Unlike the first-level warning system, the second-level warning system does not rely solely on the absolute value of pressure, but instead focuses on the instantaneous pressure change characteristics. This design concept can detect abnormal signals even before the absolute pressure value reaches the first-level warning threshold. This rate-of-change-based warning mechanism is particularly suitable for identifying the rapid pressure accumulation process in the early stages of thermal runaway. In actual cases, the system can identify this rapid change characteristic 5 to 7 minutes in advance, gaining a valuable time window for emergency response. This second-level warning mechanism, based on the pressure change rate, effectively complements the first-level warning system, forming a key component of the thermal runaway warning system and significantly improving the system's overall warning performance. Therefore, combining the dual monitoring of pressure value and pressure change rate effectively avoids false alarms or missed alarms caused by misjudging a single parameter.

[0049] Among them, the rate change threshold range is 0.05MPa / minute to 0.15MPa / minute, and can be preferably 0.1MPa / minute. The establishment of this value is based on an in-depth analysis of experimental data, and fully considers the correspondence between different pressure change modes and the internal failure process of the battery.

[0050] By monitoring the pressure value, pressure change rate and pressure difference, the pressure changes of the battery module can be comprehensively monitored from multiple dimensions, effectively improving the accuracy and reliability of the early warning.

[0051] By setting pressure detection points on the surfaces of different sodium-ion batteries, the pressure changes in the battery module can be monitored from multiple angles. Compared with methods that only set pressure detection points on the surface of a single battery cell or a local area of ​​the battery module, this method can more comprehensively reflect the operating status of the entire battery module, effectively avoiding the missed reporting of thermal runaway due to the failure to monitor local pressure changes in a timely manner, and improving the comprehensiveness and accuracy of early warning.

[0052] Furthermore, the early warning signal is a three-level early warning signal, which is issued before the first-level early warning signal or after the second-level early warning signal; or the third-level early warning signal, the second-level early warning signal and the first-level early warning signal are issued simultaneously.

[0053] like Figure 2 As shown, the present invention can more accurately reflect the severity of thermal runaway through the hierarchical mechanism of first-level warning signals, second-level warning signals and third-level warning signals, providing a basis for taking different response measures. There is a strict logical relationship between these three warning levels. The first-level warning serves as basic monitoring and provides continuous status feedback; the second-level warning focuses on dynamic changes to improve the timeliness of the warning; the third-level warning focuses on local anomalies with the aim of enhancing spatial resolution. This hierarchical design not only improves the accuracy of the warning, but also realizes the refinement of the warning information. According to the level and frequency of the triggered warning, the monitoring strategy is automatically adjusted, such as increasing the sampling frequency, extending the data recording time, etc.

[0054] like Figure 4 and Figure 5 As shown, the present invention also proposes a thermal runaway warning system based on a sodium ion battery module, comprising: a pressure collector 110, which is provided at at least two pressure detection positions of the sodium ion battery module, the pressure detection positions being provided on the surface of the sodium ion batteries of the sodium ion battery module, and the pressure collector 110 is suitable for collecting pressure values ​​at the pressure detection positions; a data collector, which is in communication connection with the pressure collector 110, so as to synchronously obtain the pressure values ​​of at least two pressure detection positions; a data processing module, which is in communication connection with the data collector, so as to construct a dynamic pressure curve based on the pressure values ​​of at least two pressure detection positions, and obtain the pressure difference between any two pressure detection positions at the same time point based on the dynamic pressure curve, and if the pressure difference is greater than the pressure difference threshold, a warning signal is issued.

[0055] In this embodiment, the thermal runaway warning system for sodium-ion battery modules includes a pressure collector 110, a data collector, and a data processing module. The pressure collector 110 is attached to the surface of the sodium-ion battery to monitor the surface pressure. When the battery expands, indicating an increase in pressure, this pressure change is captured by the sensor and converted into an electrical signal, reflecting the extent of the expansion. In practical applications, the pressure detection system offers greater flexibility in deployment. Ultra-thin pressure sensors can be cleverly integrated into the battery module, enabling real-time monitoring without disrupting normal battery operation.

[0056] To prevent corrosion of the sensor by battery fluid, the housing of the pressure collector 110 is encapsulated with corrosion-resistant materials to ensure long-term stable operation. The pressure collector 110 uses a piezoresistive thin film sensor with a thickness of less than 0.2mm. It is ultra-thin and flexible, and can perfectly fit the battery surface without affecting the normal operation of the battery. The surface of the piezoresistive thin film sensor has been specially treated and coated with a layer of highly thermally conductive insulating material, which ensures effective heat transfer and avoids the risk of electrical short circuits. The effective measurement area of ​​each pressure collector 110 is 15mm×15mm, with a measurement range of 0-10MPa and a resolution of 1Pa, which can accurately capture tiny deformations on the battery surface.

[0057] In addition, at least two pressure detection positions are set at intervals from each other and are evenly distributed on the sodium-ion battery module. The at least two pressure detection positions selected should be set at intervals from each other, which means that multiple pressure detection positions are set at intervals from each other in sequence, and cannot be too concentrated, but should be distributed in different areas of the battery module. The purpose of setting them at intervals from each other is to ensure that the pressure changes at different positions inside the battery module can be monitored. Because the internal heat distribution and pressure changes of the sodium-ion battery module may not be uniform during operation, especially when thermal runaway occurs, abnormal changes in heat and pressure may first appear in a local area. By setting pressure detection points at different locations, these local changes can be captured more comprehensively, thereby improving the accuracy of the early warning.

[0058] In addition to being spaced apart, pressure monitoring locations should be evenly distributed throughout the sodium-ion battery module. Even distribution means that these monitoring locations should follow a regular pattern and interval to evenly cover all parts of the battery module. This ensures that pressure changes in every area are effectively monitored, further improving the comprehensiveness and reliability of early warnings.

[0059] This layout of the pressure detection positions can be flexibly adjusted according to the specific shape and size of the battery module and is suitable for different types of sodium-ion battery modules.

[0060] It can be understood that the pressure detection position is set on one of the sodium ion batteries in the sodium ion battery module, and the pressure contact point is arranged in the center of the large surface of the battery, such as Figure 5 shown.

[0061] The collaborative work of two high-precision sensors enables real-time monitoring of battery surface deformation and early warning of thermal runaway. The core concept of this technical solution is to utilize the unique volume expansion characteristics of sodium-ion batteries during the charge and discharge process to capture changes in mechanical pressure on the battery surface and identify potential thermal runaway risks in advance.

[0062] Specifically, the sodium-ion battery module includes thirteen sodium-ion batteries, among which pressure detection positions are provided in the middle of the surface of the fourth sodium-ion battery and the middle of the surface of the tenth sodium-ion battery. For a standard module consisting of 13 batteries, a group of thin-film pressure sensors are arranged on the surface of the 4th and 10th battery cells respectively. This arrangement has been rigorously optimized by simulation and verified by experiments, and can capture the pressure distribution characteristics of the module as a whole to the maximum extent. The sensor at the 4th battery cell is mainly responsible for monitoring the pressure changes in the front half of the module, while the sensor at the 10th battery cell focuses on monitoring the status of the back half of the module. The collaborative work of the two sensors can not only achieve comprehensive coverage of the entire module, but also detect local anomalies through comparative analysis.

[0063] To verify the effectiveness of this invention, a systematic experimental validation was conducted. Using a standard 13-cell sodium-ion battery module, a 0.5C overcharge thermal runaway test was conducted at an ambient temperature of 25°C. The results demonstrated that the system accurately captures battery pressure changes during the charge and discharge process, with a pressure measurement error of less than 5%. In thermal runaway simulations, the system successfully identified thermal runaway precursors minutes in advance, achieving a 98% warning accuracy rate.

[0064] Specifically, the sodium-ion battery module uses commercially produced sodium-ion batteries, with a single cell capacity of 185Ah and a total module capacity of 2405Ah. The experimental environment temperature was controlled at 25±1°C and humidity was maintained at 50±5% RH to simulate the typical operating environment of an energy storage power station.

[0065] In terms of experimental design, the focus was on overcharge thermal runaway testing at a 0.5C rate. Before the experiment began, the battery module was preconditioned through a complete charge and discharge cycle to ensure that all cells were in the same initial state. During the experiment, a constant current charging mode was used, with a charging current of 92A (0.5C) and a cutoff voltage of 9V per cell. Conventional parameters such as temperature, voltage, and current were also recorded for comparison and analysis with the pressure monitoring results.

[0066] During the experiment, the first sensor was installed in the fourth section of the module, and the second sensor was installed on the surface of the battery in the tenth section. The first and second sensors were thin-film pressure sensors, tightly adhered to the battery surface via aerogel and wirelessly connected to the data acquisition system. A high-precision temperature sensor and voltage acquisition module were also connected as controls.

[0067] After the overcharge experiment began, the pressure at the first sensor rose to 0.82 MPa at 55 minutes, with a maximum rise rate of 0.014 MPa / minute. It then rose sharply, reaching 6.1 MPa at 93 minutes, with a maximum rise rate of 0.151 MPa / minute, almost 10 times the previous stage. The pressure then entered a slow rise phase, rising by 0.33 MPa in 11 minutes from 93 minutes to 104 minutes. At 104 minutes, the battery experienced thermal runaway and the sensor failed.

[0068] The second sensor's pressure reading at 55 minutes was 1.1 MPa, with a maximum rate of increase of 0.021 MPa / minute. The pressure then began to rise rapidly, reaching 5.9 MPa at 93 minutes, with a maximum rate of increase of 0.126 MPa / minute. Between 93 and 104 minutes, the pressure rose another 1.01 MPa. At 104 minutes, the battery experienced thermal runaway, and the sensor failed.

[0069] The sensor of the fourth sodium ion battery is the first sensor, and the sensor of the tenth sodium ion battery is the second sensor. Figure 2 and Figure 3The experiment observed three typical phases: Initially, the pressure rose steadily, with the maximum increase in pressure detected by the sensor for the fourth sodium-ion battery reaching 0.82 MPa, from 1.05 MPa to 1.87 MPa. During the overcharge phase, the pressure of the fourth sodium-ion battery was detected at 2.1 MPa at the first time point, exceeding the pressure threshold of 2 MPa and triggering a Level 1 warning. At the second time point, eight minutes after the first, the pressure rose from 2.1 MPa to 3.3 MPa, with a pressure difference of 1.2 MPa. The pressure of the fourth sodium-ion battery first showed an abnormal increase of 0.15 MPa / s, exceeding the rate change threshold of 0.1 MPa / minute, triggering a Level 2 warning. At the first time point, the pressure of the tenth sodium-ion battery was detected at 1.8 MPa, with a difference of 0.3 MPa between the two sensors. At the second time point, the pressure of the tenth sodium-ion battery was detected at 2.1 MPa, with a difference of 1.2 MPa between the two sensors, exceeding the pressure difference threshold of 1 MPa and triggering a Level 3 warning. Furthermore, the difference between the two sensors' measurements increased dramatically from 0.3 MPa to 1.2 MPa within eight minutes. During this time, the fourth battery's temperature only rose from 25.2°C to 33.0°C, effectively triggering the system's Level 3 warning 12 minutes in advance.

[0070] Experimental results show that the pressure monitoring system developed by this invention can accurately capture pressure changes during battery charging and discharging. During normal charging and discharging, the system detected pressure changes ranging from 0.5 to 1.2 MPa, which is consistent with theoretical calculations and has a measurement error of less than 5%.

[0071] It showed excellent early warning performance. When the battery entered the overcharge state, the system successfully captured the expansion characteristics of the electrode material caused by the insertion of sodium ions. The pressure change curve showed a typical "Z"-shaped growth trend, such as Figure 3 As shown in Figure 2, the system detected an abnormal pressure surge 12 minutes before thermal runaway occurred. Specifically, a rapid pressure rise was detected at the fourth cell, with a rate of change reaching 0.15 MPa / s. Similar characteristics were then observed in the tenth cell. This pressure propagation pattern is highly consistent with the typical development of thermal runaway. Throughout the experiment, the system triggered three warnings, achieving a 98% accuracy rate.

[0072] To further verify the system's reliability, repeatability and comparative experiments were conducted. Across 10 repeated experiments, the system's pressure measurement error standard deviation was only 0.03 MPa, demonstrating excellent repeatability and stability. Comparative experiments with traditional temperature monitoring methods showed that the proposed system improved warning times by an average of 11 minutes and reduced the false alarm rate by 85%. These data fully demonstrate the significant advantages of the proposed system in thermal runaway early warning.

[0073] In terms of engineering application, this invention fully considers the feasibility of practical deployment. The sensors are fixed with a special thermally conductive adhesive, ensuring mechanical connection reliability while maintaining the battery's heat dissipation performance. The entire monitoring system's power consumption is kept below 5W, with negligible impact on the battery module's energy efficiency. The system supports modular expansion, allowing for easy application to larger-scale energy storage systems.

[0074] Through this experiment, the following technical effects can be obtained:

[0075] (1) By monitoring pressure changes inside the battery module in real time, the present invention can identify thermal runaway precursors 5 to 8 minutes in advance, creating a critical time window for emergency response. Compared to traditional temperature and voltage monitoring methods, pressure changes can reflect internal battery anomalies earlier, such as microscopic failure processes such as SEI film decomposition and electrode material expansion, improving early warning accuracy and significantly reducing false alarm rates, providing reliable protection for the safe operation of energy storage systems.

[0076] (2) Thanks to the high sensitivity and distributed layout of thin-film pressure sensors, the system can accurately locate abnormally swollen single cells with a smaller spatial resolution, fully grasp the pressure distribution characteristics of the module, identify tiny levels of battery deformation, and provide high-precision data support for battery health status assessment.

[0077] (3) The ultra-thin flexible sensor used in this invention is less than 0.2 mm thick, with negligible impact on battery heat dissipation. The flexible packaging structure perfectly adapts to battery expansion and deformation during cycling, ensuring long-term stable operation. The sensor has a wide operating temperature range of -40°C to 150°C, capable of adapting to various extreme operating conditions, significantly improving the reliability and service life of the system.

[0078] (4) A multi-parameter fusion intelligent assessment model can be constructed, which not only supports real-time diagnosis of battery health status and early warning of faults, but also provides data support for preventive maintenance. The system supports remote monitoring and big data analysis, realizes the intelligent management of energy storage systems, and provides important technical and safety support for the large-scale commercial application of sodium-ion batteries.

[0079] To overcome the existing problem of untimely thermal runaway detection leading to explosions and fires, a multi-stage overcharge thermal runaway detection system is employed. This system effectively identifies the severity of the thermal runaway event, enabling appropriate measures to be taken based on the characteristics of each stage, thus improving detection accuracy. This invention designs different detection processes based on the different stages of thermal runaway. Each test step is interdependent and indispensable, making the entire system more scientific and effective.

[0080] The present invention can be widely used in fields such as electric vehicles, grid energy storage, and consumer electronics, providing reliable protection for the safe application of sodium-ion batteries.

[0081] The above embodiments are provided for illustrative purposes only and are not intended to limit the scope of implementation. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to provide an exhaustive list of all implementations. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A thermal runaway early warning method based on a sodium ion battery module, wherein the sodium ion battery module comprises multiple sodium ion batteries, characterized in that: The early warning method includes: Selecting at least two pressure detection positions in the sodium ion battery module, wherein the pressure detection positions are located on surfaces of different sodium ion batteries; synchronously acquiring pressure values ​​of the at least two pressure detection positions and constructing a dynamic pressure curve; Based on the dynamic pressure curve, obtaining a pressure difference between any two pressure detection positions at the same time point; If the pressure difference is greater than the pressure difference threshold, an early warning signal is issued.

2. The thermal runaway early warning method based on the sodium ion battery module according to claim 1 is characterized in that: Also includes: Based on the same time point, the pressure value at any of the pressure detection positions is compared with the pressure threshold. If any of the pressure values ​​is greater than the pressure threshold, a first-level warning signal is issued.

3. The thermal runaway early warning method based on the sodium ion battery module according to claim 2, characterized in that: The pressure threshold ranges from 1.8 MPa to 2.2 MPa.

4. The thermal runaway early warning method based on the sodium ion battery module according to claim 2, characterized in that: Also includes: Based on the dynamic pressure curve, obtaining the pressure change rate of each pressure detection position within the same time period; Before or after the first-level warning signal is issued, the pressure change rate is compared with the rate change threshold, and if the pressure change rate is greater than the rate change threshold, a second-level warning signal is issued.

5. The thermal runaway early warning method based on the sodium ion battery module according to claim 4, characterized in that: The rate change threshold ranges from 0.05 MPa / min to 0.15 MPa / min.

6. The thermal runaway early warning method based on the sodium ion battery module according to claim 4, characterized in that: The warning signal is a third-level warning signal, which is issued before the first-level warning signal or after the second-level warning signal; or the third-level warning signal, the second-level warning signal and the first-level warning signal are issued simultaneously.

7. The thermal runaway early warning method based on a sodium ion battery module according to any one of claims 1 to 6, characterized in that: The pressure difference threshold ranges from 0.9 MPa to 1.1 MPa.

8. A thermal runaway warning system based on sodium ion battery modules, characterized in that: include: A pressure collector is provided at at least two pressure detection positions of the sodium ion battery module, wherein the pressure detection positions are provided on the surface of the sodium ion batteries of the sodium ion battery module, and the pressure collector is suitable for collecting the pressure values ​​at the pressure detection positions; a data collector, communicatively connected to the pressure collector, to synchronously acquire the pressure values ​​of the at least two pressure detection positions; A data processing module is communicatively connected to the data collector to construct a dynamic pressure curve based on the pressure values ​​of the at least two pressure detection positions, and based on the dynamic pressure curve, obtains the pressure difference between any two pressure detection positions at the same time point, and issues a warning signal if the pressure difference is greater than a pressure difference threshold.

9. The thermal runaway warning system based on the sodium ion battery module according to claim 8, characterized in that: The at least two pressure detection positions are spaced apart from each other and are evenly distributed on the sodium ion battery module.

10. The thermal runaway warning system based on sodium ion battery modules according to claim 8, characterized in that: The sodium ion battery module includes thirteen sodium ion batteries, wherein a pressure detection position is provided at the middle of the surface of the fourth sodium ion battery and the middle of the surface of the tenth sodium ion battery.

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