Battery module, power battery pack and cooling control method

Abstract

The application discloses a battery module, a power battery pack and a cooling control method for realizing thermal runaway exhaust gas guiding. The battery module comprises a battery module, a detection module and an execution module. The battery module comprises, from top to bottom, a current collecting device, a liquid cooling cover plate and a cell array. The three elements are closely attached and have a through flow guiding hole, so that the thermal runaway gas and smoke are discharged to the outside of the battery pack through a channel and an exhaust pipe. The cooling control method controls the cooling of the battery module according to the battery monomer temperature detected by the detection module of the battery module and the smoke indication of the execution module according to the pre-set multi-stage temperature threshold. The application has the advantages that the thermal runaway gas is guided into the current collecting box and discharged through the exhaust pipe, and cannot spread in the power battery pack, thereby affecting the work of other battery modules, and the secondary damage of the thermal runaway gas to other battery monomers or battery modules is avoided, and the thermal safety performance of the battery pack is greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power battery packs, and particularly relates to a battery module and a cooling control method for realizing heat runaway exhaust flow guide. BACKGROUND

[0002] With wide popularization of new energy vehicles, the number of new energy vehicle fire accidents also increases year by year, attracting attention of the industry and the whole society. The heat runaway of power batteries is an important cause of new energy vehicle fire accidents. However, the heat runaway triggering mechanism of the power battery is not clear, the causes are various, and the unanticipated heat runaway is difficult to reproduce, which restricts the design of the power battery emergency management system and causes new energy vehicle fire fighting problems.

[0003] The existing power battery pack is mostly connected with battery cells in a module and placed in the battery pack, or the battery cells are directly connected to form a battery pack, and there is no other material to separate the battery cells and the battery pack. This structure can improve the space utilization rate of the battery pack, but this device does not consider the heat runaway gas flow guide, which is fatal to the normal working battery cells or modules. The existing heat runaway gas flow guide method of the power battery pack mainly includes a heat pipe flow guide method, a liquid cooling flow guide method and an air cooling flow guide method. The heat pipe flow guide method guides the battery heat runaway gas to the outside through the heat pipe to reduce the temperature of the battery; the liquid cooling flow guide method guides the battery heat runaway gas to the outside through the liquid cooling flow channel to reduce the temperature of the battery; and the air cooling flow guide method guides the battery heat runaway gas to the outside through the air cooling flow channel to reduce the temperature of the battery. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a battery module, a power battery pack and a cooling control method for realizing heat runaway exhaust flow guide. When the battery heat runaway occurs, the flow guide device of the device guides the heat runaway gas to a specific area of the gas collector box, and the gas is discharged through the exhaust pipe, so as to effectively control the flow of the battery heat runaway gas, avoid the accumulation of the gas to cause accidents, and also dissipate heat, thereby effectively reducing the temperature of the battery and improving the service life and reliability of the battery.

[0005] The first aspect of the present application is to provide a battery module for realizing heat runaway exhaust flow guide, which comprises a battery module, a detection module and an execution module; the battery module comprises a current collecting device, a liquid cooling cover plate and a battery cell array from top to bottom in sequence;

[0006] The current collecting device comprises a current collecting box body, the current collecting box body is a hollow structure, a plurality of first flow guide holes are arranged on the bottom wall facing the liquid cooling cover plate; one side wall of the current collecting box body is provided with an exhaust pipe, the exhaust pipe can extend out of the outer box body of the power battery pack, and the thermal runaway gas is discharged to the outside through the exhaust pipe;

[0007] The liquid cooling cover plate comprises a liquid cooling pipeline and a plurality of second flow guide holes; the liquid cooling pipeline is arranged in an S shape in the liquid cooling cover plate; a plurality of second flow guide holes are arranged on the top and bottom of the liquid cooling cover plate; the number, contour and position of the second flow guide holes on the top of the liquid cooling cover plate are matched with the number and position of the first flow guide holes, and the positions of the second flow guide holes on the top and bottom are correspondingly arranged to ensure smooth exhaust;

[0008] The battery monomer is provided with an exhaust valve on the top; the number, contour and position of the exhaust valve are matched with the second flow guide holes on the bottom of the liquid cooling cover plate;

[0009] The bottom wall of the current collecting device is attached to the top wall of the liquid cooling cover plate, the bottom wall of the liquid cooling cover plate is attached to the top of the battery monomer, the exhaust valve is in communication with the second flow guide holes on the bottom of the liquid cooling cover plate, the second flow guide holes on the top of the liquid cooling cover plate are in communication with the first flow guide holes, and an air flow channel is formed; when the battery monomer is in thermal runaway, the thermal runaway gas and smoke of the battery monomer flow into the liquid cooling cover plate through the second flow guide holes on the bottom of the liquid cooling cover plate, the liquid cooling pipeline 3 preliminarily cools the gas, the gas flows into the current collecting box body through the second flow guide holes on the top of the liquid cooling cover plate and the first flow guide holes, and is discharged to the outside of the battery pack through the exhaust pipe;

[0010] The detection module comprises a first temperature sensor, a second temperature sensor and a smoke sensor; the smoke sensor and the first temperature sensor are located in the current collecting box body, the smoke sensor is used for detecting the smoke generation in the current collecting box body, and the first temperature sensor is used for detecting the temperature in the current collecting box body, so as to be ready to extinguish the fire at any time; the second temperature sensor is located at the center of the outer wall of each battery monomer, and is used for detecting the temperature of the battery monomer; and the elements in the temperature detection module are in CAN bus communication with the control module of the power battery pack.

[0011] The execution module comprises a liquid inlet control valve of the liquid cooling pipeline, a first nozzle and a second nozzle, which are electrically connected with the control module; the liquid inlet control valve is arranged at the liquid inlet of the liquid cooling pipeline, and is used for adjusting the water flow speed in the liquid cooling pipeline; the first nozzle and the second nozzle S1 are located in the current collecting box body, and the first nozzle and the second nozzle are both directed to the inside of the current collecting box body; the first nozzle is used for spraying inert gas into the current collecting box body, and the second nozzle is used for fire fighting in the current collecting box body.

[0012] The second aspect of the present application provides a power battery pack, comprising a plurality of battery modules and a control module located inside an outer box, two battery modules are connected in series through exhaust pipes, the exhaust pipe of the battery module not in contact with the outer box extends into the battery module in contact with the outer box, and the exhaust pipe in contact with the outer box extends out of the outer box of the power battery pack, so that the thermal runaway gas in the two battery modules is discharged to the outside through the exhaust pipe; the control module is used for executing the cooling control of the battery module according to the pre-set threshold and the temperature and smoke indicated by the detection module of the battery module.

[0013] Further, the working medium in the liquid cooling pipe is water.

[0014] Further, the top of the battery monomer is provided with a topological tab, and part of the top of the tab is provided with an electrical connector; the bottom of the liquid cooling cover plate is provided with a groove matched with the top profile of the battery monomer, so that the liquid cooling cover plate is tightly attached to the battery monomer.

[0015] Further, a fireproof bag and a heat insulation plate arranged side by side are arranged between the two adjacent battery monomers for heat insulation and fire prevention.

[0016] The third aspect of the present application provides a cooling control method of the power battery pack, comprising:

[0017] The second temperature sensor of the battery monomer monitors the temperature of each battery monomer, when the highest monitored temperature of the battery monomer in one battery module is 25-40 DEG C, the liquid inlet control valve of the battery module is adjusted to make the flow rate of the working medium entering the liquid cooling pipe be 0.3 m / s; when it is reduced to 25 DEG C or below, the liquid inlet control valve is closed, and the working medium in the pipe is stopped flowing;

[0018] When the highest monitored temperature in the battery module is 40-60 DEG C, the liquid inlet control valve of the battery module is adjusted to make the flow rate of the working medium entering the liquid cooling pipe be 0.8 m / s; when it is reduced to 25-40 DEG C, the flow rate of the working medium entering the liquid cooling pipe is reduced to 0.3 m / s in the previous step;

[0019] If the highest monitored temperature in the battery module continues to rise, reaches 60-90 DEG C, the liquid inlet control valve of the battery module is controlled by the control module, and the flow rate of the working medium entering the liquid cooling pipe is adjusted to be 1.2 m / s; when it is reduced to 40-60 DEG C, the flow rate of the working medium entering the liquid cooling pipe is reduced to 0.8 m / s in the previous step;

[0020] If the highest monitored temperature in the battery module continues to rise, exceeds 90 DEG C, the flow rate of the working medium in the liquid cooling pipe is kept unchanged at 1.2 m / s, and the BMS inside the power battery pack is started;

[0021] When the smoke sensor detects smoke, the control module controls the first nozzle to spray nitrogen into the current collection box, reduces the equivalence ratio of the thermal runaway gas smoke, and suppresses the occurrence of combustion.

[0022] When the monitoring temperature of the first temperature sensor reaches 1000K, the control module controls the second nozzle to start fire fighting and fire extinguishing on the current collection box.

[0023] Compared with the prior art, the technical scheme of the present application has the beneficial effects that:

[0024] The current collection device, the liquid cooling cover plate and the cell array are closely attached, the first flow guide hole, the second flow guide hole and the exhaust valve are throughly arranged, a strict air passage is formed, the thermal runaway gas and the smoke gas are discharged from the cell array through the exhaust passage, the heat dissipation performance of the battery can be effectively improved; moreover, when the exhaust occurs during the thermal runaway of the battery monomer, the high-temperature gas is guided upward from the cell array located below, is preliminarily cooled in the liquid cooling cover plate, is purposefully guided into the current collection box and is discharged through the exhaust pipe, and will not spread in the power battery pack, thereby affecting the work of other battery modules, the secondary damage of the thermal runaway gas to other battery monomers or battery modules is avoided, and the thermal safety performance of the battery pack is greatly improved.

[0025] The liquid cooling cover plate is in close contact with the cell array above, the requirement of the fast heat dissipation cooling is guaranteed at the same time as the fastening requirement between the cover plate and the battery is considered, and the overall stability of the battery pack is strengthened.

[0026] The control method sets multiple temperature thresholds, can continuously increase the working fluid flow rate according to the battery monomer temperature, and timely fights fire when the thermal runaway occurs. DETAILED DESCRIPTION

[0027] Figure 1 The overall structure diagram of the power battery pack described in the embodiment;

[0028] Figure 2 The exploded view of the battery module in the embodiment;

[0029] Figure 3 The thermal runaway gas flow guide schematic diagram;

[0030] Figure 4 The top view of the liquid cooling cover plate and the cell array, for the purpose of clearly showing the liquid cooling pipeline, the second flow guide hole, the tab and the electrical connecting piece, the box body of the liquid cooling cover plate is not shown.

[0031] In the figure:

[0032] 1: current collection box 2: exhaust pipe 3: liquid cooling pipeline

[0033] 4: liquid cooling cover plate 5: second flow guide hole 6: tab

[0034] 7: Battery cell; 8: Electrical connector; 9: Vent valve

[0035] 10: Heat insulation board; 11: Fireproof bag; S0: First nozzle

[0036] S1: Second nozzle; T0: Smoke sensor; T1: First temperature sensor

[0037] T2: Second temperature sensor 12: Outer casing Detailed Implementation

[0038] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The specific embodiments described are only for explanation and illustration of the present invention and are not intended to limit the present invention.

[0039] like Figure 1 As shown, a power battery pack suitable for new energy electric vehicles includes an outer casing 12, multiple battery modules located inside the outer casing, and a control module. Each battery module includes an exhaust pipe 2. Two battery modules are connected in series via exhaust pipes. The exhaust pipe 2 of the battery module that does not contact the outer casing 12 extends into the battery module that does contact the outer casing 12, while the exhaust pipe 2 of the battery module that does contact the outer casing 12 extends out of the outer casing of the power battery pack. This allows thermal runaway gases from the two battery modules to be discharged to the outside through the exhaust pipe 2, without contacting the internal cell array of the battery pack. The control module is used to perform cooling control on the battery modules based on preset thresholds and temperature and smoke indications detected by the detection module of the battery modules.

[0040] like Figure 2 As shown, the battery module includes a battery module, a detection module, and an execution module. The battery module, from top to bottom, includes a current collector, a liquid-cooled cover plate, and a cell array. The current collector includes a current collector housing 1 and an exhaust pipe 2. The current collector housing 1 has a hollow structure, with a first guide hole at its bottom (facing the liquid-cooled cover plate). An exhaust pipe 2 extends out of the current collector housing 1 from one side wall of the current collector housing 12, venting thermal runaway gas to the outside without contacting the cell array inside the battery pack. A hole is provided on the side wall opposite to the exhaust pipe 2 for connecting to the exhaust pipe 2 of the connected battery module. The current collector housing 1, not in contact with the outer housing 12, only needs one side wall with the exhaust pipe 2; the side wall opposite to the exhaust pipe 2 does not require a hole.

[0041] like Figure 4As shown, the liquid cooling cover plate 4 is a hollow structure, which includes a liquid cooling pipe 3 and a second flow guide hole 5. The top and bottom of the liquid cooling cover plate 4 are provided with five second flow guide holes 5, and the positions of the second flow guide holes on the top and bottom are correspondingly arranged to ensure smooth exhaust. The liquid cooling pipe 3 is laid in an S shape inside the liquid cooling cover plate 4, and the internal working medium is water. The bottom of the liquid cooling cover plate 4 has a groove matched with the outer contour of the tab and the electrical connector. When the liquid cooling cover plate 4 is buckled on the tab and the electrical connector as the cover plate of the tab 6 and the electrical connector 8, the liquid cooling cover plate 4 can be in full contact with the tab and the electrical connector located on the top of the battery monomer 7, facilitating the cooling and heat dissipation of the tab. The second flow guide hole 5 penetrates the liquid cooling cover plate 4 longitudinally. The bottom of the current collector box 1 is tightly attached to the top of the liquid cooling cover plate 4 to ensure that the thermal runaway gas does not leak out. The number, contour and position of the second flow guide hole 5 on the top correspond to those of the first flow guide hole on the bottom of the current collector box 1, so that the first flow guide hole and the second flow guide hole are connected in series for the circulation of thermal runaway gas.

[0042] The battery monomer 7 includes five battery monomers 7 arranged side by side. The top of the battery monomer 7 has two tabs 6 protruding from the top. The battery monomers 7 at the head and tail ends each have a tab 6 on the top without an electrical connector 8, forming the positive and negative electrodes of the battery monomer array. The tabs 6 on the top of the remaining battery monomers 7 are connected to the tabs 6 on the top of the battery monomers 7 on the right side through an electrical connector 8. The top of the battery monomer 7 is also provided with an exhaust valve 9. The number, contour and position of the exhaust valve 9 are matched with those of the second flow guide hole 5 on the bottom of the liquid cooling cover plate 4, so that the exhaust valve and the second flow guide hole are connected in series to ensure that the thermal runaway gas does not leak out when the battery monomer array is tightly buckled with the liquid cooling cover plate. Adjacent two battery monomers 7 are provided with fireproof bags 11 and heat insulation plates 10 arranged side by side for heat insulation and fire prevention. The arrangement sequence of two adjacent battery monomers, fireproof bags and heat insulation plates is: battery-fireproof bag-heat insulation plate-battery. The size of the heat insulation plate 10 and the fireproof bag 11 is matched with the size of the side wall of the battery monomer. The heat insulation plate 10 is a SiO2-Al2O3 aerogel with a thickness of 3 mm. The exhaust valve described herein is a structure provided with the battery monomer. When the internal pressure of the battery monomer exceeds the threshold value of the exhaust valve, the exhaust valve can be opened.

[0043] As Figure 3As shown, the bottom wall of the current collecting device is attached to the top wall of the liquid cooling cover plate, the bottom wall of the liquid cooling cover plate is attached to the top of the battery cell array, the second flow guide hole 5 at the top of the liquid cooling cover plate 4 is in communication with the first flow guide hole at the bottom of the current collecting box 1, the second flow guide hole 5 at the bottom of the liquid cooling cover plate 4 is in communication with the exhaust valve 9 on the battery monomer 7, the thermal runaway gas generated by the thermal runaway of the battery monomer flows into the liquid cooling cover plate 4 and the current collecting box 1 in turn through the exhaust valve 9 (the arrow in the figure indicates the flow direction of the thermal runaway gas), and is discharged to the outside of the battery pack through the exhaust pipe 2, and the liquid cooling pipe 3 in the liquid cooling cover plate 4 can realize the cooling of the thermal runaway gas. This design ensures that the thermal runaway gas and smoke cannot be discharged to the outside of the battery module, but can only flow to the exhaust pipe along the gas channel.

[0044] The detection module includes a first temperature sensor T1, a second temperature sensor T2, and a smoke sensor T0; the smoke sensor T0 and the first temperature sensor T1 are both located inside the current collecting box 1, the smoke sensor T0 is used to detect the smoke generation in the current collecting box 1, and the first temperature sensor T1 is used to detect the temperature in the current collecting box 1, so as to be ready to extinguish the fire at any time. The second temperature sensor T2 is located at the center of one of the side walls outside each battery monomer 7, and is used to detect the temperature of the battery monomer. Each element in the temperature detection module communicates with the control module using CAN bus.

[0045] The execution module includes a liquid inlet control valve of the liquid cooling pipe, a first nozzle S0, and a second nozzle S1, all of which are electrically connected with the control module; the liquid inlet of the liquid cooling pipe 3 is provided with a liquid inlet control valve for adjusting the water flow rate therein; the first nozzle S0 and the second nozzle S1 are both located inside the current collecting box 1, and both of them are directed towards the inside of the current collecting box 1; the first nozzle S0 is used to spray nitrogen into the current collecting box 1, and the second nozzle S1 is used for fire extinguishing in the current collecting box 1.

[0046] The cooling control method of the battery module by the control module of the power battery pack is as follows:

[0047] The second temperature sensor T2 monitors the temperature of each battery monomer 7 and transmits it to the control module; when the highest monitoring temperature in the battery module is 25-40℃ (i.e. the highest monitoring temperature in all battery monomers in the current battery module), the control module controls the liquid inlet control valve in the execution module of the battery module to adjust the flow rate of the working medium entering the liquid cooling pipe 3 to 0.3m / s; when it drops to 25℃ or below, the liquid inlet control valve is closed to continue monitoring the temperature of each battery monomer 7 in the battery module.

[0048] When the highest monitored temperature in the battery module continues to rise, reaches 40-60℃, the control module controls the liquid inlet control valve of the battery module, adjusts the flow rate of the working medium entering the liquid cooling pipeline 3 to 0.8 m / s; when it drops to 25-40℃, it returns to the previous step to reduce the flow rate of the working medium entering the liquid cooling pipeline 3 to 0.3 m / s;

[0049] When the highest monitored temperature in the battery module continues to rise, reaches 60-90℃, the control module controls the liquid inlet control valve of the battery module, adjusts the flow rate of the working medium entering the liquid cooling pipeline 3 to 1.2 m / s; when it drops to 40-60℃, it returns to the previous step to reduce the flow rate of the working medium entering the liquid cooling pipeline 3 to 0.8 m / s;

[0050] When the highest monitored temperature in the battery module continues to rise, exceeds 90℃, the flow rate of the working medium in the liquid cooling pipeline 3 remains unchanged at 1.2 m / s, and the internal BMS of the power battery pack is started;

[0051] When the smoke sensor T0 detects smoke, the control module controls the first nozzle S0 to spray nitrogen into the current collector box 1, reduces the equivalence ratio of the thermal runaway gas smoke, and suppresses the occurrence of combustion;

[0052] When the monitored temperature of the first temperature sensor T1 reaches 1000K, the control module controls the second nozzle S1 to start fire fighting and fire extinguishing on the current collector box 1.

[0053] Although the preferred embodiments of the present application are described above in combination with the drawings, the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are only illustrative and not restrictive. Those skilled in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and these all belong to the protection scope of the present application.

Claims

1. A power battery pack, characterized in that, The application relates to a power battery pack, which comprises a plurality of battery modules and a control module arranged in an outer box body, two of the battery modules are connected in series through exhaust pipes, the exhaust pipe (2) of the battery module not in contact with the outer box body (12) extends into the battery module in contact with the outer box body (12), the exhaust pipe (2) in contact with the outer box body (12) extends out of the outer box body of the power battery pack, so that the thermal runaway gas in the two battery modules is discharged to the outside through the exhaust pipe (2); the control module is used for executing module cooling control on the battery module according to a preset threshold and the temperature and smoke indicated by the detection module of the battery module; The battery module comprises a battery module, a detection module and an execution module; the battery module comprises, from top to bottom, a current collecting device, a liquid cooling cover plate and a battery cell array; The current collecting device comprises a current collecting box body (1), the current collecting box body (1) is a hollow structure, a plurality of first flow guide holes are arranged on the bottom wall of the current collecting box body (1) facing the liquid cooling cover plate; one side wall of the current collecting box body (1) is provided with an exhaust pipe (2), the exhaust pipe can extend out of the outer box body of the power battery pack, and the thermal runaway gas is discharged to the outside through the exhaust pipe; The liquid cooling cover plate (4) comprises a liquid cooling pipeline (3) and a plurality of second flow guide holes (5) arranged inside; the liquid cooling pipeline (3) is arranged in an S shape inside the liquid cooling cover plate (4); a plurality of second flow guide holes (5) are arranged on the top and bottom of the liquid cooling cover plate (4); the number, contour and position of the second flow guide holes (5) on the top of the liquid cooling cover plate (4) are matched with those of the first flow guide holes, and the second flow guide holes (5) on the top and bottom are correspondingly arranged to ensure smooth exhaust; The battery cell array comprises a plurality of battery monomers (7) arranged side by side, an exhaust valve is arranged on the top of the battery monomer (7), the number, contour and position of the exhaust valve (9) are matched with those of the second flow guide holes (5) arranged on the bottom of the liquid cooling cover plate (4); The bottom wall of the current collecting device is attached to the top wall of the liquid cooling cover plate, the bottom wall of the liquid cooling cover plate is attached to the top of the battery cell array, the exhaust valve is communicated with the second flow guide holes (5) arranged on the bottom of the liquid cooling cover plate (4), the second flow guide holes (5) on the top of the liquid cooling cover plate (4) are communicated with the first flow guide holes, and an air flow channel is formed; when the battery cell array appears thermal runaway, the thermal runaway gas and smoke of the battery monomer flow into the liquid cooling cover plate through the second flow guide holes (5) arranged on the bottom of the liquid cooling cover plate (4), the gas is preliminarily cooled by the liquid cooling pipeline (3), then flows into the current collecting box body through the second flow guide holes (5) on the top of the liquid cooling cover plate (4) and the first flow guide holes, and is discharged to the outside of the battery pack through the exhaust pipe (2). The detection module comprises a first temperature sensor (T1), a second temperature sensor (T2), and a smoke sensor (T0); the smoke sensor (T0) and the first temperature sensor (T1) are both located inside the current collection box body (1), the smoke sensor (T0) is used for detecting the smoke generation inside the current collection box body (1), and the first temperature sensor (T1) is used for detecting the temperature inside the current collection box body (1); the second temperature sensor (T2) is located at the center of the outer wall of each battery monomer (7) and is used for detecting the temperature of the battery monomer, and each element in the detection module is in CAN bus communication with the control module of the power battery pack. The execution module comprises a liquid inlet control valve of the liquid cooling pipe, a first nozzle (S0) and a second nozzle (S1), which are all electrically connected with the control module of the power battery pack; the liquid inlet control valve is arranged at the liquid inlet of the liquid cooling pipe (3) and is used for adjusting the water flow speed in the liquid cooling pipe (3); the first nozzle (S0) and the second nozzle (S1) are both located inside the current collection box body (1), and the first nozzle (S0) and the second nozzle (S1) both face the inside of the current collection box body (1); the first nozzle (S0) is used for spraying inert gas into the current collection box body (1), and the second nozzle (S1) is used for fire fighting in the current collection box body (1). When in use, the second temperature sensor (T2) monitors the temperature of each battery monomer (7), when the highest monitored temperature of the battery monomers in one battery module is 25-40℃, the liquid inlet control valve of the battery module is adjusted so that the flow speed of the working medium entering the liquid cooling pipe (3) is 0.3m / s; when it falls below 25℃, the liquid inlet control valve is closed, and the working medium in the pipe stops flowing; When the highest monitored temperature of the battery module is 40-60℃, the liquid inlet control valve of the battery module is adjusted so that the flow speed of the working medium entering the liquid cooling pipe (3) is 0.8m / s; when it falls to 25-40℃, the flow speed of the working medium entering the liquid cooling pipe (3) is reduced to 0.3m / s according to the previous step; When the highest monitored temperature of the battery module continues to rise and reaches 60-90℃, the control module controls the liquid inlet control valve of the battery module, and the flow speed of the working medium entering the liquid cooling pipe (3) is adjusted to 1.2m / s; when it falls to 40-60℃, the flow speed of the working medium entering the liquid cooling pipe (3) is reduced to 0.8m / s according to the previous step; When the highest monitored temperature of the battery module continues to rise and exceeds 90℃, the flow speed of the working medium in the liquid cooling pipe (3) is kept unchanged at 1.2m / s, and the BMS inside the power battery pack is started; When the smoke sensor (T0) detects smoke, the control module controls the first nozzle (S0) to spray nitrogen into the current collection box body (1), so as to reduce the equivalence ratio of the thermal runaway gas smoke and inhibit the occurrence of combustion; When the monitored temperature of the first temperature sensor (T1) reaches 1000K, the control module controls the second nozzle (S1) to start fire fighting and extinguishing in the current collection box body (1).

2. The power battery pack of claim 1, wherein, The working medium in the liquid cooling pipe is water.

3. The power battery pack of claim 1, wherein, The battery monomer (7) top topology tab (6), part of the tab (6) top has electrical connector; The bottom of the liquid cooling cover plate (4) has a groove matched with the top profile of the battery monomer (7), which is used for closely fitting the liquid cooling cover plate (4) with the tab (6).

4. The power battery pack of claim 1, wherein, Fireproof bags (11) and heat insulation plates (10) arranged side by side are arranged between two adjacent battery monomers (7) for heat insulation and fire prevention.

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