Explosion-proof lithium battery fire extinguishing system and fire extinguishing method thereof

Abstract

The invention provides an explosion-proof lithium battery fire extinguishing method and system. The method comprises the following steps: arranging a temperature sensor with a unique identifier on each battery module; the temperature is detected in real time through a temperature sensor, and the temperature change rate is calculated; when the temperature is lower than a first preset temperature threshold value and the change rate exceeds a preset change rate threshold value, a temperature sensing spray head around the corresponding module is controlled to spray a fire extinguishing medium; when the temperature reaches a first preset temperature threshold value, a temperature sensing nozzle around a corresponding module is started, the spreading direction of thermal runaway is judged, and preventive injection is conducted in the pre-judged direction; and when the temperature exceeds a second preset temperature threshold value, each temperature sensing spray head is controlled to spray. The system comprises an explosion-proof lithium battery box, a fire-fighting device, a detection device and a control device, wherein the control device comprises a data acquisition module, a data processing module, a control module and an alarm module. According to the invention, through a hierarchical control strategy, local-to-global fire extinguishing measure upgrading is realized, and lithium battery thermal runaway accidents can be effectively prevented and controlled.

Description

Technical Field

[0001] The present invention belongs to the technical field of explosion-proof lithium battery fire extinguishing systems, and specifically relates to an explosion-proof lithium battery fire extinguishing system and a fire extinguishing method thereof. Background Art

[0002] With the trend of new energy replacing traditional energy, lithium-ion batteries have gradually become the main power batteries for mining equipment with their advantages of high energy density, high discharge power and long cycle life, and are widely used in electric mining equipment such as mining electric monorail cranes and mining trackless rubber-wheeled vehicles. Compared with traditional fuel power, lithium batteries not only have significant advantages in energy efficiency and environmental protection, but also promote the development of mining equipment towards electrification, intelligence and low carbonization, providing important support for the construction of green mines.

[0003] However, in recent years, thermal runaway accidents of lithium batteries in the civilian field have aroused widespread concern. Thermal runaway refers to the uncontrollable temperature rise of the battery under conditions such as internal short circuit, high temperature or overcharge, which may eventually lead to dangers such as fire and explosion. Although the application of existing lithium batteries in the civilian field is relatively mature, the occurrence of thermal runaway accidents still poses a threat to personal safety and property safety. This problem is particularly prominent in the application of mining equipment. Due to the closed operating environment, dense equipment and concentrated operating personnel in the mine, once a thermal runaway accident of a lithium battery occurs, it is very easy to cause major safety hazards and property losses.

[0004] Therefore, mining users have put forward higher requirements for the safe use of lithium battery power sources, especially in complex working conditions such as high temperature, humidity, and dust. How to effectively prevent and control the thermal runaway of lithium batteries has become a technical problem that needs to be solved urgently. The existing technology mainly prevents the risk of thermal runaway by means of monitoring the temperature of the battery management system and setting current limiting protection, but these methods have certain limitations in dealing with sudden thermal runaway accidents. Summary of the invention

[0005] The purpose of the present invention is to provide an explosion-proof lithium battery fire extinguishing system and a fire extinguishing method thereof in view of the above problems. Through the layered response of the fire-fighting device, combined with the temperature sensor and the intelligent monitoring system, the early detection, early warning and rapid cooling and fire extinguishing functions of the battery thermal runaway are realized, so as to improve the safety of mining lithium batteries and ensure the safe operation of mining equipment.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a method for extinguishing fire of an explosion-proof lithium battery, comprising the following steps:

[0007] A temperature sensor with a unique identifier is arranged on each battery module, and the temperature of each battery module is detected in real time by the temperature sensor;

[0008] Calculate the rate of change of the battery module temperature over time based on the temperature data of each battery module collected in real time by the temperature sensor;

[0009] When it is detected that the temperature of any battery module is lower than a first preset temperature threshold but the temperature change rate exceeds a preset change rate threshold, the temperature sensing nozzles around the corresponding battery module are controlled to spray a fire extinguishing medium;

[0010] When it is detected that the temperature of any battery module reaches the first preset temperature threshold, the temperature sensing nozzles around the corresponding battery module are automatically turned on and spray the fire extinguishing medium;

[0011] When it is detected that the temperature of any battery module exceeds a second preset temperature threshold, all temperature-sensing sprinklers are controlled to spray a fire extinguishing medium;

[0012] Wherein, the second preset temperature threshold is higher than the first preset temperature threshold.

[0013] In a possible embodiment, when it is detected that the temperature of the battery module reaches the first preset temperature threshold, the method further includes:

[0014] Determine the possible direction of thermal runaway spread;

[0015] Start the temperature-sensing sprinkler in the predicted spreading direction for preventive spraying.

[0016] In a possible embodiment, the step of determining the direction of thermal runaway propagation includes:

[0017] Obtain temperature data of other battery modules around the battery module with thermal runaway;

[0018] determining a heat transfer trend according to distribution characteristics of the temperature data;

[0019] A possible direction of thermal runaway propagation is determined based on the heat transfer trend.

[0020] In a possible embodiment, an alarm step is also included, specifically including:

[0021] When it is detected that the temperature change rate of any battery module exceeds the preset change rate threshold, a first-level alarm signal is issued;

[0022] When it is detected that the temperature of any battery module exceeds the first preset temperature threshold, a secondary alarm signal is issued;

[0023] When it is detected that the temperature of any battery module exceeds the second preset temperature threshold, a third-level alarm signal is issued.

[0024] In a possible embodiment, the first-level alarm signal includes a flashing yellow warning light and an intermittent beeping sound; the second-level alarm signal includes a flashing orange warning light and a continuous beeping sound; and the third-level alarm signal includes a rapid flashing red warning light and a high-decibel continuous beeping sound.

[0025] In a possible embodiment, the first preset temperature threshold is 68° C., the second preset temperature threshold is 79° C., and the preset change rate threshold is 20° C. / min.

[0026] The present invention also provides an explosion-proof lithium battery fire extinguishing system, comprising:

[0027] An explosion-proof lithium battery box, wherein a battery cavity is provided inside, and a plurality of battery modules are accommodated in the battery cavity;

[0028] A fire-fighting device, a pressurized container arranged outside the explosion-proof lithium battery box, a fire-fighting pipeline connected to the pressurized container, and a plurality of temperature-sensing nozzles arranged along the fire-fighting pipeline; wherein the fire-fighting pipeline extends into the battery cavity, and at least one temperature-sensing nozzle is arranged around each battery module and directed toward it;

[0029] A detection device, a temperature sensor configured on each of the battery modules, each of the temperature sensors having a unique identifier;

[0030] The control device is connected to the temperature-sensing nozzle and the detection device, and is configured to execute the above-mentioned explosion-proof lithium battery fire extinguishing method.

[0031] In a possible embodiment, the control device includes a power management system, and the power management system includes:

[0032] Data acquisition module: connected to the temperature sensor to receive temperature data;

[0033] Data processing module: It includes: a temperature change rate calculation unit, which is used to calculate the change rate of the battery module temperature over time; a heat spread analysis unit, which is used to analyze the spread direction of thermal runaway;

[0034] Control module: controls the opening of the corresponding temperature-sensing nozzle according to the analysis results of the data processing module;

[0035] Alarm module: connected to the data processing module and configured as follows:

[0036] When it is detected that the temperature change rate of any battery module exceeds the preset change rate threshold, a first-level alarm signal is issued, wherein the first-level alarm signal includes a flashing yellow warning light and an intermittent beeping sound;

[0037] When it is detected that the temperature of any battery module exceeds the first preset temperature threshold, a secondary alarm signal is issued, wherein the secondary alarm signal includes a flashing orange warning light and a continuous beeping sound;

[0038] When it is detected that the temperature of any battery module exceeds the second preset temperature threshold, a three-level alarm signal is issued, and the three-level alarm signal includes a red warning light flashing quickly and a high-decibel continuous beeping sound.

[0039] In a possible embodiment, the temperature-sensitive nozzle is a fusible alloy nozzle.

[0040] In a possible embodiment, a fire extinguishing medium is provided in the pressurized container, and the fire extinguishing medium is a perfluorohexanone solution.

[0041] Beneficial effects of the present invention:

[0042] A switch from local to global fire extinguishing protection strategy is adopted to avoid the escalation of thermal runaway accidents, and corresponding control measures are taken at different temperature thresholds to form a complete protection system. Through dual monitoring of temperature value and temperature change rate, the precursors of thermal runaway can be discovered in time and early warning can be achieved. Each battery module is equipped with an independent temperature-sensing nozzle, which can realize accurate fire extinguishing of a single abnormal module; through thermal spread analysis, the direction of thermal runaway diffusion is predicted, and the nozzle in the predicted direction is started in advance to effectively block the spread of thermal runaway; a three-level alarm and fire extinguishing mechanism is adopted, and reasonable temperature threshold parameters are set to ensure that the system responds promptly and reliably. The fire extinguishing device using an external pressurized container can accommodate more fire extinguishing solution, preparing for graded rapid cooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a structural diagram of an explosion-proof lithium battery fire extinguishing system provided in one embodiment of the present invention.

[0044] Figure 2 A flow chart of a fire extinguishing method of an explosion-proof lithium battery fire extinguishing system provided in one embodiment of the present invention.

[0045] The text labels in the figure indicate: 1. Fire-fighting device; 2. Fire-fighting pipeline; 3. Temperature sensor; 4. Temperature sensing nozzle; 5. Battery module; 6. Data acquisition module; 7. Power management system cavity; 8. Battery cavity; 9. Lithium battery box. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings. The description in this part is only exemplary and explanatory and should not have any limiting effect on the protection scope of the present invention.

[0047] This embodiment provides an explosion-proof lithium battery fire extinguishing system, which aims to effectively solve the safety hazards caused by thermal runaway of lithium batteries in mining equipment. The system realizes early and continuous fire extinguishing of lithium batteries through a multi-level fire response structure, thereby ensuring that mining equipment can be quickly handled when an abnormality occurs.

[0048] refer to Figure 1 The explosion-proof lithium battery includes a lithium battery box 9. The lithium battery box 9 adopts an explosion-proof shell structure, which includes three chambers, namely a battery chamber 8, a power monitoring system chamber 7 and a wiring chamber. The battery chamber 8 accommodates multiple battery modules 5. The battery modules 5 are arranged at certain intervals. The power management system is arranged in the power management system chamber 7. The power management system is used to protect the safety of the lithium battery to prevent dangerous situations such as overcharging, over-discharging, overcurrent and short circuit.

[0049] Each battery module 5 is composed of a plurality of battery cells, which are arranged in a certain structural form, such as series connection or parallel connection, according to the use requirements and load requirements of the equipment.

[0050] In some embodiments, reference Figure 1 A fire fighting device is provided on the lithium battery box 9, and the function of the fire fighting device is to provide overall fire extinguishing protection for all battery modules 5 in the lithium battery box 9. The device includes a pressurized container, and optionally, a perfluorohexanone solution is stored in the pressurized container, and the container is installed outside the lithium battery box 9. Optionally, a mounting frame is provided outside the box body of the lithium battery box 9, and the pressurized container 1 is fixedly mounted on the mounting frame.

[0051] A fire-fighting pipeline 2 is connected to the pressurized container 1 . The pipeline extends from the outside of the lithium battery box 9 into the battery cavity 8 and is arranged along the arrangement direction of the battery modules 5 to ensure that all battery modules 5 can be sprayed for cooling and fire extinguishing.

[0052] In some possible embodiments, a plurality of temperature-sensing nozzles 4 are arranged along the fire-fighting pipeline 2. Each nozzle can be automatically activated when the temperature is detected to exceed a first preset temperature threshold (e.g., 68°C), and the fire-extinguishing medium in the pressurized container 1 is quickly released from the corresponding temperature-sensing nozzle 4. The fire-fighting pipeline 2 is arranged around the battery module 5, ensuring that at least one temperature-sensing nozzle 4 is arranged around each battery module 5 and facing it. In this embodiment, one battery module 5 is configured with two temperature-sensing nozzles 4.

[0053] In some practicable embodiments, the temperature-sensitive nozzle 4 is a fusible alloy nozzle, and when a fire occurs, the ambient temperature rises. When the temperature reaches the melting point of the fusible alloy, the alloy plug melts, the nozzle is no longer blocked, and the fire extinguishing medium is quickly ejected from the nozzle.

[0054] In some implementations, the temperature-sensing nozzle 4 can also be heated by the electronic control system to melt it to remove the blockage, thereby realizing electronic start-up. The electronic control opening method is mainly used for the early opening of the temperature-sensing nozzle, which is mainly reflected in two situations. One is that the temperature change rate of the battery module is very fast, but it has not yet reached the opening temperature of the temperature-sensing nozzle, and it needs to be opened in advance; the other situation is that the temperature of any battery module has reached the second preset temperature threshold and is facing out of control. At this time, all the unopened temperature-sensing nozzles in the battery cavity need to be opened to achieve rapid cooling.

[0055] Since the external space is relatively ample, the capacity of the pressurized container 1 is not limited by the internal space of the lithium battery box 9, and more fire extinguishing media, such as perfluorohexanone solution, can be stored. This external pressurized container 1 can quickly transport a large amount of fire extinguishing media into the battery cavity when needed, ensuring that when the thermal runaway reaches a serious level, large-scale cooling and fire extinguishing can be carried out, thereby quickly controlling the fire. In addition, as the reserve of the fire extinguishing medium increases, the temperature inside the entire battery cavity 8 can be rapidly reduced, avoiding high temperature from further causing thermal runaway of other battery modules 5. In addition, arranging the pressurized container 1 outside the box can reduce the direct contact between the fire extinguishing medium source and the high-temperature components in the battery cavity, avoiding problems such as premature leakage of the fire extinguishing medium or increased container pressure due to high temperature, thereby improving the safety and reliability of the system. By adopting this external large-capacity fire extinguishing device, the system can provide sufficient fire extinguishing media at different stages of thermal runaway of the lithium battery, achieve longer cooling and protection, and effectively ensure the stability and safety of the mining battery system.

[0056] In some possible implementations, the power management system of the control device includes the following functional modules:

[0057] The data acquisition module is directly connected to the temperature sensor. Its main function is to receive the temperature data of each battery module. By collecting temperature information in real time, it provides basic data support for subsequent data processing and control.

[0058] The data processing module includes: a temperature change rate calculation unit for calculating the change rate of the battery module temperature over time; and a heat propagation analysis unit for analyzing the propagation direction of thermal runaway.

[0059] Among them, a possible implementation of the temperature change rate calculation unit is as follows:

[0060] ① Obtain the temperature data of each temperature sensor through a preset sampling time interval (for example, every 1 second);

[0061] ② Calculate the temperature value of the current sampling period and the temperature value of the previous sampling period:

[0062] Temperature change rate = (current temperature value - temperature value of the previous cycle) / sampling time interval;

[0063] ③ Perform sliding average processing on the calculated temperature change rate to eliminate the influence of instantaneous fluctuations;

[0064] ④Transmit the processed temperature change rate data to the thermal runaway judgment unit.

[0065] A possible implementation of the heat spread analysis unit specifically includes the following steps:

[0066] 1) Data acquisition: Establish a detection area centered on the abnormal battery module; obtain real-time data of all temperature sensors in the area;

[0067] 2) Temperature field analysis: construct a two-dimensional temperature distribution matrix; calculate the temperature gradient vector field; determine the direction in which the temperature rises fastest;

[0068] 3) Predictive processing: Determine the main direction of heat transfer based on the temperature gradient field; identify high-risk areas where thermal runaway may spread; output location information for preventive injection.

[0069] The control module is responsible for controlling the temperature-sensing nozzle. Its specific functions include: receiving signals from the data processing module; and controlling the start-up of the temperature-sensing nozzle according to preset conditions.

[0070] The alarm module is connected to the data processing module and has a multi-level alarm mechanism, as follows:

[0071] Level 1 alarm: When the temperature change rate exceeds the preset threshold, the yellow warning light flashes and an intermittent beep sounds.

[0072] Second level alarm: When the temperature exceeds the first preset temperature threshold, the orange warning light will flash and a continuous beep will sound.

[0073] Level 3 alarm: When the temperature exceeds the second preset temperature threshold, the red warning light will flash quickly and a high-decibel continuous beep will be emitted.

[0074] By adopting the above technical solution, through the coordinated work of various functional modules, all-round monitoring and timely warning of lithium battery temperature are achieved, while ensuring the reliable operation of the fire extinguishing system. The system has a reasonable structure, clear division of functional modules, and strong practicality.

[0075] In some embodiments, a method for extinguishing a fire of an explosion-proof lithium battery is provided, comprising the following steps:

[0076] S100: a temperature sensor with a unique identifier is provided on each battery module, and the temperature of each battery module is detected in real time by the temperature sensor.

[0077] Step S100 aims to obtain the temperature data of each battery module and distinguish the data of different modules, specifically, a temperature sensor is installed on each battery module, and each temperature sensor has a unique identifier, so that the system can identify which sensor data comes from which battery module.

[0078] S200: Calculate the temperature data of each battery module collected in real time by the temperature sensor and the rate of change of the battery module temperature over time.

[0079] The system periodically collects temperature data from each battery module and calculates the rate of change of temperature over time based on the collected data. This usually involves comparing the temperature difference between adjacent time points and dividing it by the time interval.

[0080] S300: When it is detected that the temperature of any battery module is lower than a first preset temperature threshold but the temperature change rate exceeds a preset change rate threshold, control the temperature-sensing sprinklers around the corresponding battery module to spray a fire extinguishing medium.

[0081] Early intervention is carried out before the battery module temperature reaches a dangerous level to prevent thermal runaway from developing further. When it is detected that the temperature of a battery module is lower than the first preset temperature threshold (for example, 68°C), but the temperature change rate exceeds the preset change rate threshold (for example, 20°C / min), the system will control the temperature-sensing sprinklers around the battery module to spray the fire extinguishing medium.

[0082] S400: When it is detected that the temperature of any battery module reaches the first preset temperature threshold, the temperature sensing nozzles around the corresponding battery module are controlled to automatically open and spray the fire extinguishing medium.

[0083] The first preset temperature threshold here is the response temperature of the temperature sensing nozzle, that is, when the temperature sensing nozzle responds, the fire extinguishing medium is automatically sprayed from the nozzle. Once the first preset temperature is reached, it means that the battery module may be out of control. At this time, it is necessary to prevent its large-scale out of control. When it is detected that the battery module temperature reaches the first preset temperature threshold, it also includes:

[0084] ① Determine the possible direction of thermal runaway spread. The steps to determine the direction of thermal runaway spread include:

[0085] 1) Obtain the temperature data of other battery modules around the battery module with thermal runaway;

[0086] 2) determining a heat transfer trend based on the distribution characteristics of the temperature data;

[0087] 3) Determine the direction in which the thermal runaway may spread based on the heat transfer trend.

[0088] ② Start the temperature-sensing nozzle in the predicted spreading direction to carry out preventive spraying.

[0089] When it is detected that the temperature of any battery module reaches a first preset temperature threshold, the temperature sensing nozzles around the corresponding battery module are automatically opened and directed to spray the abnormal battery module.

[0090] The system also performs thermal runaway propagation analysis:

[0091] 1) Determine the possible direction of thermal runaway propagation: analyze the temperature gradient of adjacent battery modules; consider the arrangement of battery packs; and determine the most likely propagation path based on the heat conduction characteristics.

[0092] 2) Preventive spraying execution: Start the temperature-sensing nozzles in the predicted direction of spread; carry out preventive spraying on potentially affected areas; and form a barrier zone to prevent the spread of thermal runaway.

[0093] The above technical solution combines precise spraying of target areas with preventive spraying, which can not only effectively control abnormal battery modules, but also prevent the spread of thermal runaway, thereby improving the effectiveness and reliability of explosion-proof lithium battery fire extinguishing methods.

[0094] S500: When it is detected that the temperature of any battery module exceeds a second preset temperature threshold, all temperature-sensing sprinklers are controlled to spray a fire extinguishing medium.

[0095] When the temperature of a single battery module reaches a very high level (e.g. 79°C), comprehensive fire extinguishing is initiated and all temperature-sensing sprinklers are opened by electronic control to prevent the fire from spreading to other battery modules.

[0096] By adopting the above technical solution, timely launching comprehensive injection control can effectively prevent the thermal runaway of a single battery module from turning into a large-scale fire, and maximize the safety of the entire battery pack. This solution has the characteristics of rapid response and comprehensive coverage, and can effectively prevent the expansion of disasters.

[0097] In some embodiments, the explosion-proof lithium battery fire extinguishing method further includes an alarm step, specifically including:

[0098] Step 1: Real-time monitoring of the temperature changes of the battery module. The temperature of the battery module is continuously monitored by setting a temperature sensor in the battery module.

[0099] Step 2: Issue graded alarm signals based on monitoring data:

[0100] 1) Level 1 alarm: When the temperature change rate of any battery module exceeds the preset change rate threshold, the system automatically triggers a level 1 alarm signal, which is manifested by flashing yellow warning lights and intermittent beeps to remind staff to pay attention to the battery pack status.

[0101] 2) Level 2 alarm: When the temperature of any battery module exceeds the first preset temperature threshold, the system automatically triggers the level 2 alarm signal, which is manifested by flashing orange warning lights and continuous beeps, prompting staff to take preventive measures.

[0102] 3) Level 3 alarm: When the temperature of any battery module exceeds the second preset temperature threshold, the system automatically triggers the level 3 alarm signal, which is manifested by a rapid flashing red warning light and a high-decibel continuous beep, prompting the staff to immediately start the emergency response procedure.

[0103] The hierarchical alarm mechanism in this embodiment is a dual monitoring of temperature and temperature change rate, combined with visual and auditory dual warning methods, which can prompt the staff to take corresponding protective measures in a timely and effective manner, and has strong practicality. The above technical solution can achieve early warning of abnormal lithium battery temperature, provide sufficient preparation time for the implementation of subsequent fire extinguishing measures, and effectively improve the reliability and safety of the explosion-proof lithium battery fire extinguishing method.

[0104] In some embodiments, the data transmission step of the explosion-proof lithium battery fire extinguishing method specifically includes:

[0105] When the system issues an alarm signal of any level, the following information will be sent to the preset monitoring terminal in real time:

[0106] 1) Alarm level: including the status information of level 1 alarm, level 2 alarm or level 3 alarm;

[0107] 2) Alarm time: record the specific time when the alarm is triggered;

[0108] 3) Unique identification of temperature sensor: used to accurately locate the abnormal battery module;

[0109] 4) Temperature data: Contains the real-time temperature value when the alarm is triggered.

[0110] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0111] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. The above is only a preferred implementation of the present invention. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the protection scope of the present invention.

Claims

1. A method for extinguishing an explosion-proof lithium battery fire, characterized in that: The following steps are involved: A temperature sensor with a unique identifier is arranged on each battery module, and the temperature of each battery module is detected in real time by the temperature sensor; Calculate the rate of change of the battery module temperature over time based on the temperature data of each battery module collected in real time by the temperature sensor; When it is detected that the temperature of any battery module is lower than a first preset temperature threshold but the temperature change rate exceeds a preset change rate threshold, the temperature sensing nozzles around the corresponding battery module are controlled to spray a fire extinguishing medium; When it is detected that the temperature of any battery module reaches the first preset temperature threshold, the temperature sensing nozzles around the corresponding battery module are automatically turned on and spray the fire extinguishing medium; When it is detected that the temperature of any battery module exceeds a second preset temperature threshold, all temperature-sensing sprinklers are controlled to spray a fire extinguishing medium; Wherein, the second preset temperature threshold is higher than the first preset temperature threshold.

2. The method for extinguishing an explosion-proof lithium battery according to claim 1, characterized in that: When it is detected that the temperature of the battery module reaches the first preset temperature threshold, the method further includes: Determine the possible direction of thermal runaway spread; Start the temperature-sensing sprinkler in the predicted spreading direction for preventive spraying.

3. The method for extinguishing an explosion-proof lithium battery according to claim 2, characterized in that: The step of determining the direction of thermal runaway propagation includes: Obtain temperature data of other battery modules around the battery module with thermal runaway; determining a heat transfer trend according to distribution characteristics of the temperature data; A possible direction of thermal runaway propagation is determined based on the heat transfer trend.

4. The method for extinguishing an explosion-proof lithium battery according to claim 1, characterized in that: It also includes alarm steps, including: When it is detected that the temperature change rate of any battery module exceeds the preset change rate threshold, a first-level alarm signal is issued; When it is detected that the temperature of any battery module exceeds the first preset temperature threshold, a secondary alarm signal is issued; When it is detected that the temperature of any battery module exceeds the second preset temperature threshold, a third-level alarm signal is issued.

5. The method for extinguishing an explosion-proof lithium battery according to claim 4, characterized in that: The first-level alarm signal includes a flashing yellow warning light and an intermittent beeping sound; the second-level alarm signal includes a flashing orange warning light and a continuous beeping sound; the third-level alarm signal includes a rapid flashing red warning light and a high-decibel continuous beeping sound.

6. The method for extinguishing an explosion-proof lithium battery according to claim 1, characterized in that: The first preset temperature threshold is 68° C., the second preset temperature threshold is 79° C., and the preset change rate threshold is 20° C. / min.

7. An explosion-proof lithium battery fire extinguishing system, characterized in that: include: An explosion-proof lithium battery box, wherein a battery cavity is provided inside the box, and a plurality of battery modules are contained in the battery cavity; A fire-fighting device, a pressurized container arranged outside the explosion-proof lithium battery box, a fire-fighting pipeline connected to the pressurized container, and a plurality of temperature-sensing nozzles arranged along the fire-fighting pipeline; wherein the fire-fighting pipeline extends into the battery cavity, and each battery module is arranged around at least one temperature-sensing nozzle facing it; A detection device, a temperature sensor configured on each of the battery modules, each of the temperature sensors having a unique identifier; A control device is connected to the temperature sensing nozzle and the detection device, and is configured to execute the explosion-proof lithium battery fire extinguishing method according to any one of claims 1 to 6.

8. The explosion-proof lithium battery fire extinguishing system according to claim 7, characterized in that: The control device includes a power management system, and the power management system includes: Data acquisition module: connected to the temperature sensor to receive temperature data; Data processing module: It includes: a temperature change rate calculation unit, which is used to calculate the change rate of the battery module temperature over time; a heat spread analysis unit, which is used to analyze the spread direction of thermal runaway; Control module: controls the opening of the corresponding temperature-sensing nozzle according to the analysis results of the data processing module; Alarm module: connected to the data processing module and configured as follows: When it is detected that the temperature change rate of any battery module exceeds the preset change rate threshold, a first-level alarm signal is issued, wherein the first-level alarm signal includes a flashing yellow warning light and an intermittent beeping sound; When it is detected that the temperature of any battery module exceeds the first preset temperature threshold, a secondary alarm signal is issued, wherein the secondary alarm signal includes a flashing orange warning light and a continuous beeping sound; When it is detected that the temperature of any battery module exceeds the second preset temperature threshold, a three-level alarm signal is issued, and the three-level alarm signal includes a red warning light flashing quickly and a high-decibel continuous beeping sound.

9. The explosion-proof lithium battery fire extinguishing system according to claim 7, characterized in that: The temperature-sensitive nozzle adopts a fusible alloy nozzle.

10. The explosion-proof lithium battery fire extinguishing system according to claim 7, characterized in that: A fire extinguishing medium is arranged in the pressurized container, and the fire extinguishing medium is a perfluorohexanone solution.

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