Thermal runaway propagation suppression device and method in lithium battery module

Abstract

The invention provides a thermal runaway propagation suppression device and method in a lithium battery module, and belongs to the technical field of safety, the thermal runaway propagation suppression device comprises an integrated self-adaptive liquid cooling system and a two-stage response control strategy, and can be used for quickly cooling a battery when the temperature of the battery is abnormally increased and extinguishing and cooling the battery at the initial stage of thermal runaway; cooling liquid or an insulating fire extinguishing medium is injected into an embedded box body in situ, abnormal heat generated by the battery is blocked in a manner that a heat insulating material and a heat conducting material are arranged at intervals, and programmed dynamic liquid supplementing in-situ injection is adopted, so that the cooling and flame suppression efficiency of the thermal runaway battery is improved, and thermal runaway propagation between the batteries is cut off. By means of the coupling effect of the heat conduction material, the heat insulation material and the fire extinguishing system, abnormal heat of the battery is effectively taken away in the modes of heat exchange enhancement, in-situ injection fire extinguishing, soaking cooling and the like, and thermal runaway propagation in the battery module is effectively blocked.

Description

Technical Field

[0001] The present invention belongs to the field of safety technology, and in particular relates to a device and method for suppressing the propagation of thermal runaway in a lithium battery module. Background Art

[0002] In recent years, with the emergence of environmental issues such as global warming, new energy sources such as wind power, tidal power, and lithium batteries have rapidly developed worldwide. Lithium batteries, with their advantages such as low self-discharge and high specific energy, have become a leader in green energy and are widely used in various aspects of industrial production. However, due to the unique properties of lithium batteries, they are highly susceptible to reactions under abusive conditions such as short circuits, extrusion, and needle puncture, which can accumulate heat. This can trigger an irreversible chain reaction, releasing large amounts of flammable gases and heat in a short period of time. Once ignited, these gases can 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. Consequently, high-specific-energy lithium batteries are often used in the power systems of electric equipment, such as electric vehicle battery packs. These high-specific-energy batteries are more susceptible to thermal runaway than traditional batteries. The high temperatures and high heat levels associated with thermal runaway make it highly likely that thermal runaway will propagate within the battery module or pack. Due to the small internal space of the battery module, traditional spray fire extinguishing is difficult to effectively remove heat, resulting in the inability to effectively suppress the propagation of thermal runaway between batteries. Therefore, rapid fire extinguishing of lithium batteries and efficient suppression of thermal runaway propagation have become technical problems that need to be solved urgently.

[0003] At present, there are still many deficiencies in the existing devices and methods for suppressing thermal runaway and fire of lithium batteries, which are mainly reflected in the following aspects: (1) Most of the existing lithium battery safety protection strategies are passively triggered, and most of them are triggered after thermal runaway, which has a certain lag and cannot effectively intervene to suppress thermal runaway in time. (2) Most of the existing safety protection methods are aimed at extinguishing open flames, and the cooling efficiency is low. It is difficult to effectively suppress the propagation of thermal runaway in the battery module, and the battery fire is easy to reignite. (3) Most of the existing safety protection methods are mainly based on spraying, which has low cooling efficiency in the narrow space of high-energy battery modules and is difficult to effectively suppress the violent jet fire and rapid temperature rise of the battery. (4) The existing research on immersion cooling methods rarely considers the problem of fluid replenishment, and there is a defect that the cooling efficiency is reduced due to high-temperature vaporization. In addition, the internal space utilization rate of most immersion cooling methods is low, resulting in a reduction in the volume energy density of the battery system. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a device and method for suppressing the propagation of thermal runaway in a lithium battery module. During the development and triggering process of thermal runaway of a lithium battery, the device and method can reduce the risk of thermal runaway, weaken or block the propagation of thermal runaway, and provide multi-level safety protection for the battery by enhancing heat exchange during abnormal temperature rise and immersion fire extinguishing during thermal runaway. The device and method can be used to prevent the propagation of thermal runaway in a lithium battery module. The device and method can be used to prevent the propagation of thermal runaway in a lithium battery module. The device and method can be used to prevent the propagation of thermal runaway in a lithium battery module. The device and method can be used to prevent the propagation of thermal runaway in a lithium battery module module. The device and method can be used to prevent the propagation of thermal runaway in a lithium battery module module.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A device for suppressing the propagation of thermal runaway in a lithium battery module, comprising an integrated adaptive liquid cooling system; the integrated adaptive liquid cooling system comprises a liquid cooling plate and an embedded box, thermal insulation material and thermal conductive material spaced between the surfaces of adjacent lithium batteries of the lithium battery module, a guide groove, and a high-voltage variable frequency pump; the liquid cooling plate is arranged on both sides of the lithium battery module; the guide groove extends along the width direction of the embedded box and is arranged in the top area of ​​the inner wall of the embedded box; when abnormal heat generation of the lithium battery module is detected, a first-level response is initiated; when thermal runaway of the lithium battery inside the lithium battery module is detected, a second-level response is initiated; the first-level response is achieved by the liquid cooling plate, the spaced arrangement The second-level response is achieved by releasing the insulating fire extinguishing medium, which enters the interior of the embedded box through the guide groove. The guide groove is sloped according to the layout of the lithium battery to divert the insulating fire extinguishing medium to the surface of the lithium battery. The high-voltage variable frequency pump controls the first-level response check valve or the second-level response check valve by receiving the action signal from the fire control unit to achieve the first-level response or the second-level response. The thermal runaway propagation suppression device is an integrated device that adaptively realizes the rapid cooling of the lithium battery module and the fire extinguishing and continuous cooling during thermal runaway.

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

[0008] A temperature sensor, a characteristic gas sensor, and a smoke sensor are installed in 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, and the coolant circulation in the liquid cooling plate is started. Through the cooperation of the liquid cooling plate, thermal conductive material and thermal insulation material, the lithium battery module is quickly cooled down;

[0010] When the signals detected by any two of the temperature sensor, characteristic gas sensor and smoke sensor meet the preset trigger conditions for the secondary response, the secondary response is triggered. The insulating fire extinguishing medium is pumped out from the storage tank through a high-voltage variable frequency pump and injected into the lithium battery module in situ through the diversion groove, forming a full immersion environment to suppress the spread of thermal runaway.

[0011] Beneficial effects:

[0012] 1. The present invention proposes an integrated adaptive liquid cooling system, including a liquid cooling plate and a guide groove symmetrically embedded in a box, a thermal management method composed of a heat conduction-insulation principle, and coupled with an in-situ injection immersion fire extinguishing suppression method. The thermal runaway module is "thermally partitioned" using insulation materials, and the in-situ injection of an insulating fire extinguishing medium is used to quickly remove the heat of the thermal runaway battery cell, forming a full immersion environment, effectively delaying or blocking the propagation of thermal runaway.

[0013] 2. The present invention takes the characteristics of thermal runaway as its starting point and adopts the symmetrical arrangement of liquid cooling plates for efficient cooling as the main strategy for suppression, which is more in line with objective laws and can effectively suppress the development of battery thermal runaway.

[0014] 3. The present invention considers the suppression of thermal runaway propagation while considering the suppression of thermal runaway, which is beneficial to controlling the thermal runaway hazard within a certain range, avoiding the occurrence of heat propagation, and reducing the risk of re-ignition of the battery system.

[0015] 4. The present invention mainly uses in-situ injection direct cooling, and the cooling efficiency is greatly improved compared with traditional spray cooling.

[0016] 5. The present invention takes into account the loss of cooling medium due to vaporization during immersion cooling and proposes a programmable liquid replenishment strategy to ensure long-term and efficient cooling. It also collects excess insulating fire extinguishing medium through a liquid collection tank to increase the recycling rate of the insulating fire extinguishing medium.

[0017] In summary, the present invention targets the characteristics of thermal runaway and thermal runaway propagation of lithium batteries. Through an integrated adaptive liquid cooling system and a two-stage response control strategy, it can rapidly cool the battery when it is abnormally heated and extinguish the fire and reduce the temperature in the early stages of thermal runaway. It uses a symmetrical embedded box with a liquid cooling plate and a guide groove, and adopts a spaced layout of thermal insulation materials and thermal conductive materials to block the abnormal heat generation of the battery, effectively delaying the spread and propagation of redundant heat in the battery system. At the same time, the programmable dynamic liquid replenishment in-situ injection and guide groove slope drainage fire extinguishing cooling methods are used to improve the cooling and flame suppression efficiency of thermal runaway batteries, and cut off the thermal runaway propagation between batteries. The present invention, with the help of the coupling effect of thermal conductive materials-insulating materials and fire extinguishing systems, effectively removes the abnormal heat generation of the battery by enhancing heat exchange, in-situ injection fire extinguishing, immersion cooling, etc., and effectively blocks the thermal runaway propagation in the battery module. The present invention is designed based on the thermal runaway of batteries and their thermal runaway propagation characteristics. It effectively suppresses battery thermal runaway through thermal isolation and heat conduction, and uses rapid in-situ injection and continuous immersion to cut off the propagation of thermal runaway in the battery module, providing multi-level and all-round protection for battery safety, efficiently cooling thermal runaway battery modules, effectively suppressing the spread of thermal runaway in the battery module, and preventing battery re-ignition and the outbreak of large-scale fires. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0019] Figure 2 It is a structural diagram of the liquid cooling plate and the embedded box;

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

[0021] Figure 4 Schematic diagram of the structure of the diversion trough.

[0022] Among them, the figures are marked as: 1-lithium battery, 2-thermal conductive material, 3-thermal insulation material, 4-liquid cooling plate, 5-detection system, 6-in-situ injection interface, 7-liquid cooling plate filling port, 8-guide groove, 9-liquid collecting tank, 10-high-pressure variable frequency pump, 11-fire control unit, 12-liquid storage tank, 13-insulating fire extinguishing medium, 14-first-level response one-way valve, 15-second-level response one-way valve. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other. The present invention is further described below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 2 , Figure 3 , Figure 4 As shown, a device for suppressing the propagation of thermal runaway within a lithium battery module according to an embodiment of the present invention includes an integrated adaptive liquid cooling system comprising a liquid cooling plate 4 and an embedded enclosure. The device implements both a primary response and a secondary response. The primary response is rapid cooling of the lithium battery 1 in response to abnormal heat generation; the secondary response is efficient fire extinguishing and rapid temperature reduction in response to thermal runaway.

[0025] A plurality of lithium batteries 1 constitute a lithium battery module, and thermal insulation materials 3 and thermal conductive materials 2 are placed between the lithium batteries inside the lithium battery module. 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 box by welding or other means to ensure that they are tightly fitted with the battery side wall and the embedded box side wall. The bilateral symmetrical layout can ensure uniform heat dissipation of the lithium battery module; the liquid cooling plate filling port 7 is an opening on the outside of the embedded box, and is connected to the liquid cooling plate inlet / outlet by a flange, etc., and the internal structure of the embedded box is tight; the detection system 5 is arranged in the upper position of the middle area of ​​the wall on one side of the embedded box; the guide groove 8 extends along the width direction of the embedded box and is arranged in the top area of ​​the inner wall of the box, connected by welding or other means, and the slope of the guide groove 8 is designed according to the inclination angle of the embedded box and the battery layout; at the same time, a liquid collecting tank 9 is arranged at a symmetrical position for collecting insulating fire extinguishing medium.

[0026] The coolant can flow into the guide groove 8 through the in-situ injection interface 6 and then flow out through the collecting 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 groove 8 is arranged on the inner wall surface of the embedded box, 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. , ensuring that the insulating fire extinguishing medium can efficiently reach the upper surface of the battery from all directions along the guide groove 8 for efficient cooling and fire extinguishing; the liquid collecting tank 9 is also symmetrically arranged on the inner wall of the embedded box, and the insulating fire extinguishing medium is collected and recycled after the battery is fully immersed.

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

[0028] During a first-level response, lithium batteries have high energy density and their internal battery materials are active, resulting in higher intensity and speed of heat accumulation than conventional batteries. Therefore, once under abnormal heat generation conditions, they are highly susceptible to thermal runaway. Therefore, when abnormal heat release and temperature rise in the lithium battery are detected, the integrated adaptive liquid cooling system intervenes promptly, relying on symmetrically distributed liquid cooling plates 4 to rapidly cool the abnormal lithium battery through indirect cooling, thus disrupting the conditions for thermal runaway. The hardware required for a first-level response primarily includes temperature sensors, thermal insulation material 3, thermal conductive material 2, liquid cooling plates 4, liquid cooling medium, electromagnetic selector valve, high-voltage variable frequency pump, and liquid storage tank.

[0029] Furthermore, the primary 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 the temperature measurement more accurate, the temperature used in the first-level response is provided by both the temperature sensor and the battery management system (BMS) temperature measurement.

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

[0033] Furthermore, when one of the temperature sensor signal and the BMS temperature signal exceeds 80° C., the first-level response is triggered.

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

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

[0036] Furthermore, if 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, and has an integrated liquid cooling and fire protection function. It can adopt graded response measures to adaptively adjust the system flow rate according to different heat loads. At the same time, it has an intelligent control function and can automatically adjust the flow rate and other working conditions according to the temperature and usage status of the lithium battery module.

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

[0038] (1)

[0039] Among them, q is the flow rate increased by the high-pressure variable frequency pump, the unit is m 3 / s; P is the redundant heat that needs to be removed by the system, in W; c is the specific heat capacity of the coolant, in J / kg·K; ρ is the density of the coolant, in kg / m 3 ; is the temperature rise of the coolant, in K.

[0040] Furthermore, in the present invention, the coolant flowing into the liquid cooling plate 4 can be a modified water-based insulating fire extinguishing medium, perfluorohexanone, or other liquid fire-fighting agent, which exhibits excellent flow and heat transfer properties. For applications requiring higher safety and heat transfer efficiency, a liquid with higher electrochemical stability and non-flammability can be used, offering enhanced safety, higher heat capacity, and higher thermal conductivity.

[0041] Furthermore, in order to effectively dissipate heat and contain thermal runaway to the smallest possible extent when a lithium battery experiences thermal runaway, the present invention provides intervals between thermal insulation material 3 and thermal conductive material 2. Every two lithium batteries 1 form a thermal conductive and insulating unit, arranged in a lithium battery-thermal conductive material-lithium battery-thermal insulating material arrangement. This design effectively removes heat generated during battery charging and discharging during normal operation, and effectively reduces the mutual influence between batteries through the barrier of thermal insulation material 3, which is beneficial to the temperature uniformity of the lithium battery module. Furthermore, during thermal runaway of a lithium battery, the spread of thermal runaway can be hierarchically blocked, with every two lithium batteries serving as the minimum unit, effectively slowing the spread of thermal runaway or isolating thermal runaway within the module.

[0042] Among them, the thermal insulation material 3 is 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 uses a copper heat conductive plate, which can quickly transfer the heat generated by the battery to the liquid cooling plate and take away the redundant heat.

[0044] In the secondary response, the thermal runaway of the lithium battery is severe and there is a risk of re-ignition. Traditional spray cooling and fire extinguishing are difficult to effectively suppress it, and the difficulty of suppressing thermal runaway is higher than that of ordinary batteries. Therefore, the present invention proposes an in-situ injection fire extinguishing cooling. When the fire control unit detects that the lithium battery is in thermal runaway, it promptly sends a fire extinguishing signal to the high-voltage variable frequency pump, releasing the insulating fire extinguishing medium, and entering the interior of the embedded box through the guide groove 8. The guide groove 8 is sloped according to the layout of the lithium battery, and the insulating fire extinguishing medium is quickly and efficiently delivered to the surface of the lithium battery, quickly cooling the thermal runaway lithium battery, blocking the spread of thermal runaway, and controlling the thermal runaway inside the lithium battery module. The hardware required for the secondary response mainly includes: temperature sensors, characteristic gas sensors such as CO and H2, smoke sensors, gravity sensors, fire control units, insulating fire extinguishing media, electromagnetic selection valves, and high-voltage variable frequency pumps.

[0045] Furthermore, the secondary response is triggered by characteristic gas sensors such as CO and H2, smoke sensors, and temperature sensors. The secondary response is triggered primarily by thresholds set by these sensors. The trigger logic is: trigger when any two of these three parameters are met.

[0046] Among them, the thresholds of characteristic gas sensors such as CO and H2 and smoke sensors are determined based on the thermal runaway experiment of the protected lithium battery.

[0047] The temperature sensor threshold mainly includes an absolute value threshold and an incremental threshold. The absolute temperature threshold is 150°C, and the temperature rise rate is the incremental threshold, which is set to 1.5°C / s.

[0048] Furthermore, in order to prevent the liquid from flowing back, a one-way valve is provided at the insulated fire extinguishing medium in-situ injection interface 6, which can effectively ensure that the insulating fire extinguishing medium is injected into the lithium battery module in one direction without flowing back.

[0049] Furthermore, in order to intervene in thermal runaway suppression efficiently and timely, the present invention proposes a fast filling strategy, that is, the time from the triggering of the secondary response to the complete immersion of the batteries in the lithium battery module should be completed within 3-5 seconds.

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

[0051] Furthermore, in order to compensate for the loss of insulating fire extinguishing medium due to high-temperature vaporization, the present invention relies on the cooperation of a fire control unit, a gravity sensor and a high-voltage variable frequency pump to achieve program-controlled fluid replenishment.

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

[0053] The rehydration process is triggered by gravity sensor signal feedback. Ten seconds after rapid filling begins, the gravity sensor powers up. When it detects a 30% drop in gravity, it transmits a signal to the fire control unit, restarting the high-voltage variable-frequency pump and performing intermittent or rapid rehydration according to the logic design.

[0054] Among them, the gravity sensor is a patch type gravity sensor.

[0055] The fluid replenishment dosage is controlled and determined according to the opening time of the high-pressure variable frequency pump.

[0056] Furthermore, the insulating fire extinguishing medium used in the secondary response is preferably a modified water-based insulating fire extinguishing medium, a liquid fire extinguishing agent such as perfluorohexanone, or the like. To reduce the potential for large-scale short circuits caused by aqueous insulating fire extinguishing media, the present invention employs aqueous film-forming foam or hydrogel additions to effectively reduce the insulating fire extinguishing medium's conductivity and enhance its chemical inhibition efficacy.

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

[0058] The first step is to determine the heat generated by the lithium battery. This can be determined through adiabatic accelerating calorimeter testing to determine the heat generated by thermal runaway, or by using a lookup table to calculate the heat generated by each battery group, the mass of each component, and the chemical reaction heat and combustion heat of each component.

[0059] Furthermore, the dosage of the water-based insulating fire extinguishing medium is calculated based on the heat 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 is calculated based on the heat generated by thermal runaway of the four lithium batteries.

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

[0062] (2)

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

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

[0065] During the use of lithium batteries, due to the active nature of their internal materials, when they are in extremely harsh conditions such as high temperature, the heat generated during the charging and discharging process is difficult to discharge in time and is easily accumulated inside the lithium battery. Therefore, the liquid cooling system needs to activate the first-level response to remove the heat in time.

[0066] like Figure 1 As shown, when the temperature sensor or BMS system in the lithium battery module detects the temperature of the lithium battery 1 (i.e. Figure 1 The BMS temperature or temperature sensor data) exceeds 80℃ (i.e. Figure 1 When T>80℃), it is considered that the lithium battery generates abnormal heat (i.e. Figure 1 The fire control unit sends a signal to the high-voltage variable frequency pump (i.e. Figure 1 The variable frequency pump is turned on to enhance heat exchange), and the required flow rate is calculated based on the redundant heat. The flow rate is increased by controlling the frequency to enhance heat exchange, remove the redundant heat in the lithium battery module, and effectively reduce the risk of thermal runaway. If the lithium battery temperature is not monitored to exceed 80°C, the original flow rate is maintained unchanged.

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

[0068] (3)

[0069] Among them, Q ex is the redundant heat, in kJ; is the specific heat capacity of the battery, in kJ / kg·℃; m is the mass of the single battery, in kg; T x The battery temperature detected when the temperature rises abnormally, in °C; T ave is the daily average temperature of the battery 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 to enhance the heat exchange of the liquid cooling system and more efficiently remove the heat accumulated and generated in the system.

[0071] At the same time, the present invention proposes a thermal management layout in which the heat-conducting material 2 and the heat-insulating material 3 are arranged at intervals, which can effectively perform thermal zoning on the lithium battery module, reduce the impact of abnormally heat-generating lithium batteries on adjacent normal lithium batteries, effectively insulate and efficiently exchange heat, and is conducive to controlling abnormal heat generation within a smaller range and reducing the risk of thermal runaway of the system.

[0072] When the lithium battery system encounters an emergency such as a short circuit or collision, the first-level response cannot effectively suppress the abnormal heat generation of the lithium battery in a short period of time. At this time, the temperature of the lithium battery further increases (i.e. Figure 1 The battery temperature continues to rise, triggering other internal reactions) Large-scale decomposition of the solid electrolyte membrane (SEI) occurs inside the lithium battery. The membrane shrinks and ruptures due to heat, and the exothermic process such as the reaction between the electrode and the electrolyte and the decomposition of the electrolyte further releases a large amount of heat and generates C x H y , CO, H2 and other combustible gases, as well as NO x , SO2 and other toxic gases. When two of the following three conditions are met, the secondary response is triggered: (1) the battery surface temperature T>150℃ or the battery surface temperature rise rate dT / dt>1.5℃ / s; (2) the hydrogen concentration ≥200ppm; (3) the carbon monoxide concentration ≥1500ppm.

[0073] After the secondary response is triggered, the thermal runaway lithium battery module is accurately located through the response signals of the temperature sensor and the hydrogen and carbon monoxide sensors and the physical address code. The fire control unit 11 sends the start signal to the high-voltage variable frequency pump and the gravity sensor circuit through the communication line. The high-voltage variable frequency pump starts and quickly injects the insulating fire extinguishing medium into the thermal runaway lithium battery module (i.e. Figure 1 The total high-voltage variable frequency pump is started and the perfusion begins), and the slope drainage is carried out through the guide groove 8 to quickly reach the surface of the battery where thermal runaway occurs for efficient cooling.

[0074] After a delay of about 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 loss percentage is detected to be more than 30%, that is When the high-voltage variable frequency pump is started again (i.e. Figure 1 The high-voltage variable-frequency pump in the system restarts (restarting the pump) to quickly replenish the liquid level, ensuring the cooling and fire-extinguishing efficiency of the water-based insulating fire extinguishing medium. If the loss percentage does not exceed the limit, the high-voltage variable-frequency pump will not operate. Replenishment can be configured as either rapid or timed to meet efficiency or economy requirements. Excess coolant is collected in a sump.

[0075] (4)

[0076] Where G x is the real-time system gravity, and G0 is the initial gravity when the system is working normally.

[0077] The above is only an exemplary description of the present invention and does not limit its scope of protection. Some improvements and modifications made by those skilled in the art without departing from the principle of the present invention should be regarded as within the scope of protection of the present invention.

Claims

1. A device for suppressing the propagation of thermal runaway in a lithium battery module, characterized in that: The integrated adaptive liquid cooling system includes a liquid cooling plate and an embedded box, thermal insulation materials and thermal conductive materials spaced between adjacent lithium battery surfaces of the lithium battery module, a guide groove, and a high-voltage variable frequency pump; the liquid cooling plate is arranged on both sides of the lithium battery module; the guide groove extends along the width direction of the embedded box and is arranged in the top area of ​​the inner wall of the embedded box; when abnormal heat generation of the lithium battery module is detected, the first-level response is initiated; when thermal runaway of the lithium battery inside the lithium battery module is detected, the second-level response is initiated; the first-level response is achieved through the liquid cooling plate, the thermal insulation materials and thermal conductive materials spaced apart The fire protection system is realized by releasing insulating fire extinguishing medium, which enters the interior of the embedded box through the guide groove. The guide groove diverts the fire at a slope according to the layout of the lithium battery, and delivers the insulating fire extinguishing medium to the surface of the lithium battery. The high-voltage variable frequency pump controls the action of the first-level response check valve or the second-level response check valve by receiving the action signal from the fire protection control unit to realize the first-level response or the second-level response. The thermal runaway propagation suppression device is an integrated device that adaptively realizes rapid cooling of the lithium battery module and fire extinguishing and continuous cooling during thermal runaway.

2. The device for suppressing the propagation of thermal runaway in a lithium battery module according to claim 1, wherein: The integrated adaptive liquid cooling system also includes a liquid collecting tank, 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 through a pipeline, and the high-pressure variable frequency pump is connected to an in-situ injection interface and a liquid filling port of a liquid cooling plate through a pipeline with a selection valve; the detection system is arranged at an upper position inside the embedded box, and the fire control unit is connected to the high-pressure variable frequency pump.

3. The device for suppressing the propagation of thermal runaway in a lithium battery module according to claim 2, wherein: The liquid cooling plate is provided with a serpentine or parallel flow channel inside; the liquid cooling plate, guide groove and liquid collecting groove are designed to be embedded and seamlessly connected to the inner wall of the embedded box; the liquid cooling plate is provided with a liquid cooling plate filling port, and the guide groove is provided with an in-situ injection interface; the insulating fire extinguishing medium is stored in the liquid storage tank.

4. The device for suppressing the propagation of thermal runaway in a lithium battery module according to claim 1, wherein: The thermal 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 the spread of heat when the lithium battery is out of control; the thermal insulation material is a high temperature resistant and impact resistant material with a thickness not exceeding 3mm; the thermal conductive material is a material with high rebound toughness, which is insulated and has a thickness not exceeding 2mm.

5. The device for suppressing the propagation of thermal runaway in a lithium battery module according to claim 2, wherein: 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 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 rehydration working mode to quickly replenish the loss of insulating fire extinguishing medium caused by high-temperature vaporization according to the required logic.

6. The device for suppressing the propagation of thermal runaway in a lithium battery module according to claim 5, wherein: When the first-level response occurs, the fire control unit receives an 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 sends coolant into the liquid cooling plate for circulation, thereby achieving rapid cooling when the lithium battery module generates abnormal heat.

7. The device for suppressing the propagation of thermal runaway in a lithium battery module according to claim 5, wherein: When the secondary response occurs, the fire control unit receives signals from the temperature sensor, characteristic gas sensor and smoke sensor and performs logical analysis and judgment. If it is determined that a lithium battery in the lithium battery module has thermal runaway, a secondary signal is sent to the high-voltage variable frequency pump. The high-voltage variable frequency pump draws the insulating fire extinguishing medium from the liquid storage tank, and flows it into the diversion groove through the in-situ injection interface. After slope drainage, a continuous in-situ immersion environment is formed, thereby achieving efficient fire extinguishing and rapid cooling of the lithium battery module. The excess insulating fire extinguishing medium is discharged from the collecting tank and collected for recycling.

8. The device for suppressing the propagation of thermal runaway in a lithium battery module according to claim 1, wherein: The cooling liquid and the insulating fire extinguishing medium of the liquid cooling plate are the same liquid.

9. The method for suppressing thermal runaway propagation of a device for suppressing thermal runaway propagation in a lithium battery module according to any one of claims 1 to 8, characterized in that: include: A temperature sensor, a characteristic gas sensor, and a smoke sensor are installed in 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, and the coolant circulation in the liquid cooling plate is started. Through the cooperation of the liquid cooling plate, thermal conductive material and thermal insulation material, the lithium battery module is quickly cooled down; When the signals detected by any two of the temperature sensor, characteristic gas sensor and smoke sensor meet the preset trigger conditions for the secondary response, the secondary response is triggered. The insulating fire extinguishing medium is pumped out from the storage tank through a high-voltage variable frequency pump and injected into the lithium battery module in situ through the diversion groove, forming a full immersion environment to suppress the spread of thermal runaway.

10. The method for suppressing the propagation of thermal runaway according to claim 9, characterized in that: In the first-level response, the flow path of the coolant in the liquid cooling plate is a serpentine or parallel flow path, the material of the liquid cooling plate is aluminum alloy, and the coolant is a modified water-based insulating fire extinguishing medium or a liquid fire extinguishing agent such as perfluorohexanone; the thermal insulation material is aerogel doped with ceramic fiber or silicon oxide; the thermal conductive material is a copper thermal conductive plate; in the process of 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 is started to control the rehydration strategy, and the insulating fire extinguishing medium is replenished as needed by a high-voltage variable frequency pump. The excess insulating fire extinguishing medium is discharged through a liquid collection tank and collected for recycling.

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