A device and method for suppressing thermal runaway propagation in a lithium battery module

Abstract

This invention provides a device and method for suppressing thermal runaway propagation within a lithium battery module, belonging to the field of safety technology. It includes an integrated adaptive liquid cooling system and a two-stage response control strategy. This system can rapidly cool the battery when it abnormally heats up and extinguish fires in the early stages of thermal runaway. It employs an embedded enclosure for in-situ injection of coolant or insulating fire-extinguishing medium, and uses a layout of alternating thermal insulation and thermally conductive materials to block abnormal heat generation from the battery. Programmable dynamic in-situ liquid replenishment improves the cooling and flame suppression efficiency for thermally runaway batteries, effectively cutting off the propagation of thermal runaway between batteries. This invention leverages the coupling effect of thermally conductive and insulating materials with the fire-extinguishing system to effectively remove abnormal heat generated by the battery through enhanced heat exchange, in-situ fire-extinguishing injection, and immersion cooling, effectively blocking the propagation of thermal runaway within the battery module.

Description

Technical Field

[0001] This invention belongs to the field of safety technology, specifically relating to a device and method for suppressing thermal runaway propagation in a lithium battery module. Background Technology

[0002] In recent years, with the emergence of environmental problems such as global warming, new energy sources such as wind power, tidal power, and lithium batteries have developed rapidly in various countries. Lithium batteries, with their advantages of low self-discharge rate and high specific energy, have become a leader in green energy and are widely used in various stages of industrial production. However, due to the special properties of lithium batteries, they are highly susceptible to reactions under abusive conditions such as short circuits, compression, and punctures, which can accumulate heat and trigger irreversible internal chain reactions, releasing large amounts of flammable gases and heat in a short time. Once these flammable gases are ignited, they can potentially cause large-scale fires or even explosions. In particular, with the increasing demand and frequency of lithium battery use, the specific energy of lithium batteries is constantly increasing, and high-energy-density lithium batteries are often selected for the power energy systems of electric equipment (such as battery packs for electric vehicles). These high-energy-density batteries are more prone to thermal runaway than traditional batteries, and the thermal runaway temperature is high with a large amount of heat, making it extremely easy for thermal runaway to propagate within the battery module or battery pack. Due to the limited internal space of battery modules, traditional spray-type fire extinguishing methods are unable to effectively remove heat, resulting in an inability to effectively suppress the spread of thermal runaway between batteries. Therefore, rapid fire extinguishing and efficient suppression of thermal runaway propagation in lithium batteries have become urgent technical challenges to be addressed.

[0003] Currently, existing devices and methods for suppressing thermal runaway and fire in lithium batteries still have many shortcomings, mainly reflected in the following aspects: (1) Existing lithium battery safety protection strategies are mostly passively triggered, and most of them are triggered after thermal runaway, which has a certain lag and cannot intervene in a timely and effective manner to suppress thermal runaway. (2) Existing safety protection methods are mostly aimed at extinguishing open flames, with low cooling efficiency, making it difficult to effectively suppress the propagation of thermal runaway in the battery module, and the battery fire is prone to reignition. (3) Existing safety protection methods are mostly based on spraying, which has low cooling efficiency in the narrow space of high-energy-density battery modules, making it difficult to effectively suppress the violent jet fire and rapid temperature rise of the battery. (4) Existing research on immersion cooling methods rarely considers the issue of liquid replenishment, which has the defect of reduced cooling efficiency due to high-temperature vaporization. Moreover, most immersion cooling methods have low utilization of the internal space of the box, resulting in a reduction in the volumetric energy density of the battery system. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a thermal runaway propagation suppression device and method within a lithium battery module. During the development and triggering of thermal runaway in a lithium battery, it reduces the risk of thermal runaway and weakens or blocks its propagation by enhancing heat exchange during abnormal temperature rises and immersion extinguishing during thermal runaway, thus providing multi-layered safety protection for the battery. This invention intervenes early when abnormal heat generation occurs in the early stages of battery thermal runaway. It enhances heat exchange through a symmetrically distributed liquid cooling system, efficiently cooling the abnormally hot battery and cutting off thermal runaway from its incubation and development. In the early stages of battery thermal runaway, multiple signal coupling judgments activate the fire suppression system, rapidly injecting insulating fire extinguishing media into the battery module in situ, creating a fully immersed environment for efficient fire extinguishing and continuous cooling, thus cutting off the propagation of thermal runaway.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A thermal runaway propagation suppression device within a lithium battery module includes an integrated adaptive liquid cooling system. The integrated adaptive liquid cooling system comprises a liquid cooling plate, an embedded housing, thermal insulation and thermally conductive materials spaced apart between adjacent lithium battery surfaces of the lithium battery module, flow channels, and a high-voltage variable frequency pump. The liquid cooling plate is disposed on both sides of the lithium battery module. The flow channels extend along the width of the embedded housing and are disposed in the top region of the inner wall of the embedded housing. When abnormal heat generation is detected in the lithium battery module, a primary response is initiated. When thermal runaway is detected in the lithium batteries inside the lithium battery module, a secondary response is initiated. The primary response is achieved through the liquid cooling plate and the spaced-apart materials. The system utilizes both thermal insulation and thermally conductive materials, with each pair of adjacent lithium batteries forming a thermally conductive and insulating unit. The secondary response is achieved by releasing an insulating fire extinguishing medium, which enters the interior of the embedded housing through a guide channel. The guide channel is sloped according to the layout of the lithium batteries to deliver the insulating fire extinguishing medium to the surface of the lithium batteries. The high-voltage variable frequency pump receives the action signal from the fire control unit and controls the action of the primary or secondary response check valve to achieve primary or secondary response. The thermal runaway propagation suppression device is an integrated device that adaptively achieves rapid cooling of the lithium battery module and fire extinguishing and continuous cooling during thermal runaway.

[0007] The present invention also provides a method for suppressing thermal runaway propagation in a lithium battery module, comprising:

[0008] Temperature sensors, characteristic gas sensors, and smoke sensors are installed inside the lithium battery module to monitor the temperature, characteristic gas concentration, and smoke concentration of the lithium battery module in real time.

[0009] When the temperature sensor detects that the temperature of the lithium battery module exceeds the first temperature threshold, a first-level response is triggered, which starts the circulation of coolant in the liquid cooling plate. Through the cooperation of the liquid cooling plate, thermal conductive materials and thermal insulation materials, the lithium battery module is rapidly cooled down.

[0010] When any two of the temperature sensor, characteristic gas sensor, and smoke sensor detect signals that meet the preset trigger conditions for the secondary response, the secondary response is triggered. The insulating fire extinguishing medium is then extracted from the storage tank by a high-voltage variable frequency pump and injected into the lithium battery module in situ through a guide channel, forming a fully immersed environment to suppress the propagation of thermal runaway.

[0011] Beneficial effects:

[0012] 1. This invention proposes an integrated adaptive liquid cooling system, which includes a thermal management method based on the principle of thermal conduction and insulation, symmetrically embedded liquid cooling plates and flow channels into the housing, coupled with an in-situ injection immersion fire suppression method. The thermal runaway module is divided into "thermal zones" using insulation materials, and the in-situ injection of insulating fire extinguishing medium quickly removes the heat from the thermal runaway battery cell, forming a fully immersed environment, which effectively delays or blocks the propagation of thermal runaway.

[0013] 2. Based on the characteristics of thermal runaway, this invention uses symmetrically arranged liquid cooling plates for efficient cooling as the main strategy to suppress it, which is more in line with objective laws and can effectively suppress the development of battery thermal runaway.

[0014] 3. This invention considers both the suppression of thermal runaway and the suppression of its propagation, which helps to control the hazards of thermal runaway within a certain range, avoid thermal spread, and reduce the risk of battery system reignition.

[0015] 4. This invention mainly uses in-situ injection direct cooling, which greatly improves the cooling efficiency compared with traditional spray cooling.

[0016] 5. This invention takes into account the loss of cooling medium due to vaporization during immersion cooling and proposes a programmable liquid replenishment strategy, which can ensure long-term high-efficiency cooling and collect excess insulating fire extinguishing medium through a liquid collection tank, thereby increasing the recycling rate of insulating fire extinguishing medium.

[0017] In summary, this invention addresses the characteristics of thermal runaway and its propagation in lithium batteries. Through an integrated adaptive liquid cooling system and a two-stage response control strategy, it enables rapid cooling during abnormal battery temperature rise and fire suppression in the initial stages of thermal runaway. A symmetrical embedded enclosure with liquid cooling plates and guide channels, along with an alternating arrangement of thermal insulation and thermally conductive materials, effectively blocks abnormal heat generation from the battery, delaying the spread of redundant heat within the battery system. Simultaneously, programmable dynamic in-situ liquid replenishment and sloped flow guidance in the guide channels enhance cooling and flame suppression efficiency for thermally runaway batteries, cutting off the propagation of thermal runaway between batteries. This invention leverages the coupling effect of thermally conductive and insulating materials with the fire suppression system, effectively removing abnormal heat generated by the battery through enhanced heat exchange, in-situ fire suppression, and immersion cooling, thus effectively blocking the propagation of thermal runaway within the battery module. This invention is designed to address the thermal runaway of batteries and its propagation characteristics. It effectively suppresses thermal runaway through thermal barrier and thermal conduction, and uses rapid in-situ injection and continuous immersion to cut off the propagation of thermal runaway within the battery module. It provides multi-level and all-round protection for battery safety, efficiently cools the thermal runaway battery module, effectively suppresses the spread of thermal runaway within the battery module, and prevents battery reignition and large-scale fire outbreaks. Attached Figure Description

[0018] Figure 1 This is a logic control diagram of the thermal runaway propagation suppression method in a lithium battery module according to an embodiment of the present invention;

[0019] Figure 2 This is a structural schematic diagram of the liquid cooling plate and the embedded enclosure.

[0020] Figure 3 A 3D assembly diagram of the integrated adaptive liquid cooling system and lithium battery module;

[0021] Figure 4 This is a schematic diagram of the flow guide channel.

[0022] The attached figures are labeled as follows: 1-Lithium battery, 2-Heat-conducting material, 3-Heat-insulating material, 4-Liquid-cooled plate, 5-Detection system, 6-In-situ injection interface, 7-Liquid-cooled plate injection port, 8-Guide channel, 9-Collection tank, 10-High-pressure variable frequency pump, 11-Fire control unit, 12-Storage tank, 13-Insulating extinguishing medium, 14-First-level response check valve, 15-Second-level response check valve. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. The invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 2 , Figure 3 , Figure 4 As shown, an embodiment of the present invention provides a thermal runaway propagation suppression device within a lithium battery module, comprising an integrated adaptive liquid cooling system. The integrated adaptive liquid cooling system includes a liquid cooling plate 4 and an embedded housing. The thermal runaway propagation suppression device within the lithium battery module implements a primary response and a secondary response. The primary response is rapid cooling when the lithium battery 1 generates abnormal heat; the secondary response is efficient fire suppression and rapid cooling when the lithium battery 1 experiences thermal runaway.

[0025] Multiple lithium batteries 1 constitute a lithium battery module. Inside the lithium battery module, heat-insulating material 3 and heat-conducting material 2 are placed between the lithium batteries. Liquid cooling plates 4 are symmetrically distributed on both sides of the lithium battery module. The liquid cooling plates 4 are fixed to the inner wall of the housing by welding or other methods, ensuring a tight fit with the battery side wall and the embedded housing side wall. This symmetrical layout ensures uniform heat dissipation of the lithium battery module. The liquid cooling plate injection port 7 is an opening outside the embedded housing and is connected to the liquid cooling plate inlet / outlet via flanges, ensuring a tight internal structure. The detection system 5 is located at the upper part of the middle area of ​​one side wall of the embedded housing. A flow guide trough 8 extends along the width of the embedded housing and is located at the top of the inner wall of the housing, connected by welding or other methods. The slope of the flow guide trough 8 is designed according to the inclination angle of the embedded housing and the battery layout. Simultaneously, symmetrically positioned collection tanks 9 are used for collecting insulating fire extinguishing media.

[0026] The coolant can flow into the guide channel 8 through the in-situ injection port 6 and then out through the collection tank 9; it can also flow directly into the liquid cooling plate 4 through the liquid cooling plate injection port 7 to participate in cooling. The detection system 5 is installed above the liquid cooling plate 4. The guide channel 8 is arranged on the inner wall of the embedded housing, and a reasonable slope is designed according to the relative position of the upper surface of the lithium battery and the in-situ injection port. This ensures that the insulating fire extinguishing medium can efficiently reach the upper surface of the battery from all directions along the guide channel 8 for efficient cooling and fire extinguishing; the collection tank 9 is also symmetrically arranged on the inner wall of the embedded box, and is collected and recycled after the insulating fire extinguishing medium has fully immersed the battery.

[0027] The liquid storage tank 12 and the high-pressure variable frequency pump 10 are located outside the enclosure and are connected by a liquid delivery pipeline. The insulating fire extinguishing medium 13 is stored in the liquid storage tank 12. The high-pressure variable frequency pump 10 is connected to the liquid-cooled plate injection port 7 and the in-situ injection interface 6 through pipelines with a first-level response check valve 14 and a second-level response check valve 15, respectively. The high-pressure variable frequency pump 10 and the fire control unit 11 are connected by a control line to receive first-level response and second-level response signals.

[0028] In the first-level response, lithium batteries have high energy density and active internal battery materials, resulting in a higher intensity and rate of heat accumulation compared to conventional batteries. Therefore, under abnormal heat generation conditions, they are highly susceptible to thermal runaway. Thus, when abnormal heat release and temperature rise of the lithium battery are detected, an integrated adaptive liquid cooling system intervenes promptly, using symmetrically distributed liquid cooling plates 4 to rapidly cool the abnormal lithium battery indirectly, disrupting the conditions for thermal runaway. The hardware required for the first-level response mainly includes a temperature sensor, thermal insulation material 3, thermally conductive material 2, liquid cooling plate 4, liquid cooling medium, electromagnetic selector valve, high-pressure variable frequency pump, and storage tank.

[0029] Furthermore, the Level 1 response is primarily triggered by temperature.

[0030] Furthermore, the insulating fire extinguishing medium 13 is a high latent heat liquid insulating fire extinguishing medium.

[0031] Furthermore, to make temperature measurement more accurate, the temperature used in the first-level response is provided jointly by the temperature sensor and the battery management system (BMS).

[0032] Furthermore, the temperature sensor uses a thermocouple, with a measuring point set every other lithium battery 1. The measuring points can be arranged on the busbar or the surface of the lithium battery 1 according to the actual installation situation.

[0033] Furthermore, when either the temperature sensor signal or the BMS temperature signal exceeds 80°C, a first-level response is triggered.

[0034] Furthermore, the internal flow channels of the liquid cooling plate 4 are selected to be serpentine or parallel, providing a larger heat exchange area and effectively improving heat exchange efficiency. The liquid cooling plate 4 is equipped with insulation material 3 to prevent heat from spreading to the edges and below the insulation material 3.

[0035] Furthermore, the liquid cooling plate 4 is made of aluminum alloy, which has good thermal conductivity and plasticity.

[0036] Furthermore, such as Figure 3 As shown, the integrated adaptive liquid cooling system is equipped with a high-pressure variable frequency pump 10 and a fire control unit 11. It has integrated liquid cooling and fire protection functions, and can adaptively adjust the system flow rate according to different heat loads using graded response measures. It also has intelligent control functions, and can automatically adjust the flow rate and other operating conditions according to the temperature and usage status of the lithium battery module.

[0037] Furthermore, during the process of adjusting the flow rate of the integrated adaptive liquid cooling system, the increase in flow rate of the high-pressure variable frequency pump is determined according to the following formula (1):

[0038] (1)

[0039] Where q represents the increased flow rate of the high-pressure variable frequency pump, in meters per second (m³). 3 / s; P is the redundant heat that the system needs to remove, in W; c is the specific heat capacity of the coolant, in J / kg·K; ρ is the density of the coolant, in kg / m³ 3 ; This represents the temperature rise of the coolant, measured in Kelvin (K).

[0040] Furthermore, in this invention, the coolant introduced into the liquid cooling plate 4 can be a preferably modified water-based insulating fire extinguishing medium, perfluorohexanone, or other liquid fire extinguishing agents, which have both good flow characteristics and heat exchange characteristics. For application scenarios with higher requirements for safety and heat exchange efficiency, liquids with higher electrochemical stability and non-flammability can be used, which have higher safety, higher heat capacity, and higher thermal conductivity.

[0041] Furthermore, to effectively dissipate heat and control thermal runaway within a small area in the event of a lithium battery thermal runaway, this invention employs a spaced-out thermal insulation material 3 and a thermally conductive material 2. Each pair of lithium batteries 1 forms a thermally conductive and thermally insulating unit, arranged in a lithium battery-thermal conductive material-lithium battery-thermal insulation material configuration. This design effectively removes heat generated during battery charging and discharging during normal operation and effectively reduces mutual interference between batteries through the barrier effect of the thermal insulation material 3, thus contributing to the temperature uniformity of the lithium battery module. Simultaneously, during lithium battery thermal runaway, the propagation of thermal runaway can be graded and blocked in pairs of lithium batteries as the smallest unit, effectively slowing down the spread of thermal runaway or preventing it from spreading within the module.

[0042] Among them, the thermal insulation material 3 is made of aerogel, which is doped with ceramic fibers or silicon oxides to effectively improve the high temperature resistance of the thermal insulation material.

[0043] Among them, the thermal conductive material 2 is a copper thermal conductive plate, which can quickly conduct the heat generated by the battery to the liquid cooling plate and remove excess heat.

[0044] In a Level 2 response, the thermal runaway of lithium batteries is severe and carries a risk of reignition. Traditional spray cooling and fire suppression methods are insufficient to effectively suppress it, making thermal runaway suppression more challenging than with ordinary batteries. Therefore, this invention proposes an in-situ injection-type fire suppression cooling system. When the fire control unit detects thermal runaway in the lithium battery, it promptly sends a fire suppression signal to the high-voltage variable frequency pump, releasing an insulating fire suppression medium. This medium enters the embedded housing through a guide channel 8, which slopes according to the lithium battery layout, rapidly and efficiently delivering the insulating fire suppression medium to the lithium battery surface. This quickly cools the thermally runaway lithium battery, preventing the spread of thermal runaway and confining it within the lithium battery module. The hardware required for a Level 2 response mainly includes: temperature sensors, characteristic gas sensors such as CO and H2, smoke sensors, gravity sensors, a fire control unit, insulating fire suppression medium, an electromagnetic selector valve, and a high-voltage variable frequency pump.

[0045] Furthermore, the secondary response is triggered by characteristic gas sensors (such as CO and H2), a smoke sensor, and a temperature sensor. The triggering of the secondary response primarily relies on the threshold values ​​of these sensors. The triggering logic is as follows: triggering occurs when any two of the three parameters are satisfied.

[0046] The threshold values ​​for characteristic gas sensors such as CO and H2, as well as smoke sensors, are determined based on thermal runaway experiments of the protected lithium battery.

[0047] The temperature sensor's thresholds mainly include absolute thresholds and incremental thresholds. The absolute temperature threshold is 150℃, and the temperature rise rate is the incremental threshold, set to 1.5℃ / s.

[0048] Furthermore, to prevent liquid backflow, a one-way valve is installed at the in-situ injection port 6 for the insulating fire extinguishing medium, which can effectively ensure that the insulating fire extinguishing medium is injected into the lithium battery module in one direction without backflow.

[0049] Furthermore, in order to intervene in thermal runaway suppression efficiently and in a timely manner, this invention proposes a rapid filling strategy, namely, the process from the triggering of the secondary response to the complete immersion of the battery in the lithium battery module should be completed within 3-5 seconds.

[0050] Furthermore, to meet the requirements of rapid in-situ injection, the high-pressure variable frequency pump in the secondary response is selected with a high-pressure frequency.

[0051] Furthermore, to compensate for the loss of insulating extinguishing medium caused by high-temperature vaporization, this invention relies on the cooperation of a fire control unit, a gravity sensor, and a high-voltage variable frequency pump to achieve programmable liquid replenishment.

[0052] Among them, rapid or intermittent fluid replenishment can be achieved by programming the fire control unit 11, that is, fluid replenishment can be achieved through program control.

[0053] The replenishment process is triggered by feedback signals from the gravity sensor. Ten seconds after the rapid filling starts, the gravity sensor powers on and operates. When the gravity sensor detects a gravity loss of 30%, it transmits a feedback signal to the fire control unit, which then restarts the high-pressure variable frequency pump and performs intermittent multiple replenishments or rapid replenishment according to the logic design.

[0054] The gravity sensor is a patch-type gravity sensor.

[0055] The dosage of fluid replacement is controlled and determined based on the start-up time of the high-pressure variable frequency pump.

[0056] Furthermore, the preferred insulating extinguishing medium for a Level II response is a modified water-based insulating extinguishing medium, perfluorohexanone, or other liquid fire extinguishing agents. To reduce the potential for large-scale short circuits caused by water-containing insulating extinguishing media, this invention uses aqueous film-forming foam or hydrogel additives to effectively reduce the conductivity of the insulating extinguishing medium and enhance its chemical inhibition performance.

[0057] Furthermore, the dosage of the water-based insulating fire extinguishing medium is determined according to the following method:

[0058] The first step is to determine the heat generation of the lithium battery. This can be achieved through experimental testing with an adiabatic accelerated calorimeter, or by calculating and estimating the heat generation of the lithium battery by referring to tables based on the distribution ratio of each component, the mass of each component, and the values ​​of the heat of chemical reaction and the heat of combustion of each component.

[0059] Furthermore, the dosage of the water-based insulating fire extinguishing medium is calculated based on the thermal balance between the heat released by the thermal runaway of the lithium battery and the heat absorbed by the water-based insulating fire extinguishing medium.

[0060] Furthermore, the dosage of the water-based insulating fire extinguishing medium was calculated based on the heat generated by the thermal runaway of the four lithium batteries.

[0061] Furthermore, the dosage of the water-based insulating fire extinguishing medium can be calculated according to the following formula (2):

[0062] (2)

[0063] Where W represents the mass of the water-based insulating fire extinguishing medium, in kg; T represents the heat released by a single lithium battery during thermal runaway, measured or estimated experimentally, in kJ; c represents the specific heat capacity of the water-based insulating fire extinguishing medium, in kJ / kg·K; T vapor It is the vaporization temperature of the water-based insulating fire extinguishing medium, measured in Kelvin (K); T en It is the storage temperature of the water-based insulating fire extinguishing medium, measured in K.

[0064] The present invention also provides a method for suppressing thermal runaway propagation within a lithium battery module, comprising:

[0065] During use, due to the active nature of its internal materials, lithium batteries are prone to heat buildup when subjected to extreme conditions such as high temperatures. As a result, the heat generated during charging and discharging is difficult to dissipate in time and tends to accumulate inside the battery. Therefore, a liquid cooling system is needed to activate a first-level response to remove the heat in a timely manner.

[0066] like Figure 1 As shown, when the temperature sensor or BMS system inside the lithium battery module detects the temperature of lithium battery 1 (i.e., Figure 1 (The temperature data obtained from the BMS or temperature sensor) exceeds 80°C (i.e. Figure 1 When T>80℃, it is considered that the lithium battery generates abnormal heat (i.e., Figure 1 The battery temperature abnormally increased, and there was a risk of the temperature continuing to rise, triggering a Level 1 response. The fire control unit sent a signal to the high-voltage variable frequency pump (i.e.,...) via the communication line. Figure 1 The variable frequency pump is turned on to enhance heat exchange. The required increase in flow rate is calculated based on the redundant heat. The flow rate is increased by controlling the frequency to enhance heat exchange and remove the redundant heat in the lithium battery module, effectively reducing the risk of thermal runaway. If the lithium battery temperature does not exceed 80°C, the original flow rate is maintained.

[0067] To ensure cooling efficiency, a margin of 1 times is reserved in the calculation of redundant heat. The redundant heat can be calculated according to the following formula (3):

[0068] (3)

[0069] Among them, Q ex Redundant heat, expressed in kJ; ρ is the specific heat capacity of the battery, in kJ / kg·℃; m is the mass of a single battery cell, in kg; T x T represents the battery temperature detected during abnormal temperature rise, in °C. ave This is the battery's average daily temperature, expressed in °C.

[0070] After calculating the redundant heat, the flow rate is calculated according to formula (2). The flow rate is further increased by controlling the frequency of the high-pressure variable frequency pump, which enhances the heat exchange of the liquid cooling system and removes the heat accumulated and generated in the system more efficiently.

[0071] Meanwhile, the present invention proposes a thermal management layout in which thermally conductive material 2 and thermal insulation material 3 are arranged alternately, which can effectively divide the lithium battery module into thermal zones, reduce the impact of abnormally heated lithium batteries on nearby normal lithium batteries, effectively insulate heat, and efficiently exchange heat, which helps to control abnormal heat generation within a small range and reduce the risk of system thermal runaway.

[0072] When a lithium battery system encounters an emergency such as a short circuit or collision, the Level 1 response cannot effectively suppress the abnormal heat generation of the lithium battery in a short period of time, and the lithium battery temperature rises further (i.e., Figure 1 As the battery temperature continues to rise, triggering other internal reactions, a large-scale decomposition of the solid electrolyte membrane (SEI) occurs inside the lithium battery. This membrane shrinks and ruptures under heat, and exothermic processes such as electrode-electrolyte reaction and electrolyte decomposition further release a large amount of heat and generate C. x H y Combustible gases such as CO and H2, as well as NO x The following three conditions are met when two of the following conditions are met: (1) Battery surface temperature T>150℃ or battery surface temperature rise rate dT / dt>1.5℃ / s; (2) Hydrogen concentration ≥200ppm; (3) Carbon monoxide concentration ≥1500ppm.

[0073] After the secondary response is triggered, the thermally runaway lithium battery module is accurately located using the response signals and physical address codes of the temperature sensor, hydrogen and carbon monoxide sensors. The fire control unit 11 sends a start signal to the high-voltage variable frequency pump and gravity sensor circuit via the communication line. The high-voltage variable frequency pump starts and rapidly injects insulating extinguishing medium into the thermally runaway lithium battery module (i.e., the lithium battery module) through the in-situ injection interface within 3-5 seconds. Figure 1 The main high-voltage variable frequency pump starts and the injection begins, and the flow is diverted at an angle through the guide channel 8 to quickly reach the surface of the battery that has experienced thermal runaway for efficient cooling.

[0074] After a delay of approximately 10 seconds, the gravity sensor circuit is powered on (i.e. Figure 1 The gravity sensor starts working), and the percentage of water-based insulating fire extinguishing medium loss is calculated in real time according to the following formula (4). When the detected loss percentage exceeds 30%, that is When this happens, feedback is sent to the control circuit and the high-voltage variable frequency pump is restarted (i.e., Figure 1 The high-pressure variable frequency pump in the system will restart to quickly replenish the liquid level, ensuring the cooling and extinguishing efficiency of the water-based insulating fire extinguishing medium; if no loss percentage exceeding the limit is detected, the high-pressure variable frequency pump will not operate. In particular, when replenishing the liquid, rapid replenishment or timed replenishment can be set as needed to meet the requirements of high efficiency or economy. Excess coolant is collected through the collection tank.

[0075] (4)

[0076] In the formula G x G0 represents the real-time system gravity, while G0 represents the initial gravity when the system is operating normally.

[0077] The above description is merely an exemplary illustration of the present invention and does not limit its scope of protection. Any improvements and modifications made by those skilled in the art without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A thermal runaway propagation suppression device within a lithium battery module, characterized in that, It provides multi-level, all-round protection for battery safety, including an integrated adaptive liquid cooling system; the integrated adaptive liquid cooling system includes a liquid cooling plate and an embedded housing, heat insulation and heat conduction materials spaced between adjacent lithium battery surfaces of the lithium battery module, a flow channel, a high-voltage variable frequency pump, and a liquid collection tank; the lithium battery, heat insulation material, and heat conduction material are arranged in a lithium battery-heat conduction material-lithium battery-heat insulation material manner. Liquid cooling plates are set on both sides of the lithium battery module; the liquid cooling plates, flow guides and liquid collection tanks adopt an embedded design and are seamlessly connected to the inner wall of the embedded housing; the flow guides extend along the width of the embedded housing and are set in the top area of ​​the inner wall of the embedded housing. When abnormal heat generation is detected in the lithium battery module, a primary response is initiated; when thermal runaway is detected in the lithium battery inside the module, a secondary response is initiated. The primary response is achieved through a liquid cooling plate and spaced-apart thermal insulation and thermally conductive materials, with each pair of adjacent lithium batteries forming a thermally conductive and insulating unit. The secondary response is achieved by releasing an insulating fire extinguishing medium, which enters the interior of the embedded housing through a guide channel. The guide channel is sloped according to the layout of the lithium batteries to deliver the insulating fire extinguishing medium to the surface of the lithium batteries. The high-voltage variable frequency pump receives an action signal from the fire control unit and controls the primary or secondary response check valve to activate either the primary or secondary response. During the secondary response, the high-voltage variable frequency pump extracts the insulating fire extinguishing medium from the storage tank and flows it into the guide channel through the in-situ injection interface, forming a continuous in-situ immersion environment through sloped flow. The thermal runaway propagation suppression device is an integrated device that adaptively achieves rapid cooling of the lithium battery module and fire extinguishing and continuous cooling during thermal runaway.

2. The thermal runaway propagation suppression device in a lithium battery module as described in claim 1, characterized in that, The integrated adaptive liquid cooling system also includes a detection system, a fire control unit, and a liquid storage tank. The liquid storage tank is connected to a high-pressure variable frequency pump via a pipeline, and the high-pressure variable frequency pump is connected to the in-situ injection interface and the liquid cooling plate injection port via a pipeline with a selection valve. The detection system is located at the top of the embedded housing, and the fire control unit is connected to the high-pressure variable frequency pump.

3. The thermal runaway propagation suppression device in a lithium battery module as described in claim 2, characterized in that, The liquid cooling plate has a serpentine or parallel flow channel inside; the liquid cooling plate has a liquid cooling plate injection port, and the flow guide groove has an in-situ injection interface; the insulating fire extinguishing medium is stored in a liquid storage tank.

4. The thermal runaway propagation suppression device in a lithium battery module as described in claim 1, characterized in that, The thermally conductive material is used to quickly transfer the heat generated by the lithium batteries on both sides to the liquid cooling plate, and the thermal insulation material is used to prevent heat spread when the lithium battery runs away. The thermal insulation material is a high-temperature resistant and impact-resistant material with a thickness of no more than 3mm. The thermally conductive material is a material with high resilience and toughness, and is insulated with a thickness of no more than 2mm.

5. The thermal runaway propagation suppression device in a lithium battery module as described in claim 2, characterized in that, The detection system includes a temperature sensor, a characteristic gas sensor, and a smoke sensor. The characteristic gases include CO and H2. The fire control unit receives the signals collected by the temperature sensor, the characteristic gas sensor, and the smoke sensor and sends a control signal to the high-voltage variable frequency pump through logical judgment. The high-voltage variable frequency pump adopts a program-controlled liquid replenishment mode to quickly replenish the insulation fire extinguishing medium loss caused by high-temperature vaporization according to the required logic.

6. The thermal runaway propagation suppression device in a lithium battery module as described in claim 5, characterized in that, When the first-level response occurs, the fire control unit receives the over-temperature signal from the temperature sensor and sends a control signal to the high-voltage variable frequency pump. The high-voltage variable frequency pump then sends the coolant into the liquid cooling plate for circulation, thereby achieving rapid cooling when the lithium battery module generates abnormal heat.

7. The thermal runaway propagation suppression device in a lithium battery module as described in claim 5, characterized in that, When the secondary response occurs, the fire control unit receives signals from the temperature sensor, the characteristic gas sensor, and the smoke sensor and performs logical analysis and judgment. If it is determined that a lithium battery in the lithium battery module has experienced thermal runaway, a secondary signal is sent to the high-voltage variable frequency pump.

8. The thermal runaway propagation suppression device in a lithium battery module as described in claim 1, characterized in that, The coolant and the insulating fire extinguishing medium of the liquid cooling plate are the same liquid.

9. A method for suppressing thermal runaway propagation in a lithium battery module according to any one of claims 1-8, characterized in that, include: Temperature sensors, characteristic gas sensors, and smoke sensors are installed inside the lithium battery module to monitor the temperature, characteristic gas concentration, and smoke concentration of the lithium battery module in real time. When the temperature sensor detects that the temperature of the lithium battery module exceeds the first temperature threshold, a first-level response is triggered, which starts the circulation of coolant in the liquid cooling plate. Through the cooperation of the liquid cooling plate, thermal conductive materials and thermal insulation materials, the lithium battery module is rapidly cooled down. When any two of the temperature sensor, characteristic gas sensor, and smoke sensor detect signals that meet the preset trigger conditions for the secondary response, the secondary response is triggered. The insulating fire extinguishing medium is then extracted from the storage tank by a high-voltage variable frequency pump and injected into the lithium battery module in situ through a guide channel, forming a fully immersed environment to suppress the propagation of thermal runaway.

10. The method for suppressing thermal runaway propagation according to claim 9, characterized in that: In the first-level response, the coolant flows through a serpentine or parallel channel within the liquid-cooled plate. The liquid-cooled plate is made of aluminum alloy, and the coolant is a modified water-based insulating fire extinguishing medium or a liquid fire extinguishing agent such as perfluorohexanone. The heat insulation material is aerogel, internally doped with ceramic fibers or silicon oxides. The heat-conducting material is a copper heat-conducting plate. During the second-level response, the loss of the insulating fire extinguishing medium is monitored in real time by a gravity sensor. When the loss percentage exceeds a preset value, the program-controlled replenishment strategy is activated, and a high-pressure variable frequency pump replenishes the insulating fire extinguishing medium as needed. Excess insulating fire extinguishing medium is discharged through a collection tank for collection and recycling.

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