Battery pack smoke control device, vehicle and parameter design method

Abstract

The present invention relates to the technical field of new energy vehicles, and in particular to a battery pack smoke control device, a vehicle and a parameter design method, wherein the battery pack smoke control device comprises: a battery pack body; an explosion-proof valve arranged on the battery pack body; and a smoke adsorption device arranged in the airway of the battery pack body. Thus, the problem of how to improve the smoke control effect of the battery pack without increasing the size of the battery pack is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a battery pack smoke control device, a vehicle and a parameter design method. Background Art

[0002] New energy sources are playing an increasingly important role in the automotive market. Lithium-ion batteries have been increasingly widely used in the power and energy storage fields due to their high energy density, long cycle life, and low self-discharge performance. In the context of large-scale application of lithium-ion batteries, the safety of lithium-ion batteries, especially power lithium-ion batteries with high energy density, has also attracted more and more attention.

[0003] After the battery cell has thermal runaway, it will produce high-temperature flue gas. In order to prevent the battery pack from being over-pressurized, an explosion-proof valve device needs to be installed to achieve the purpose of exhaust and pressure relief. For small-capacity lithium iron phosphate batteries, the smoke generated by thermal runaway is very small, and the risk of fire when discharged into the environment is low. However, large-capacity batteries or ternary batteries produce a lot of high-temperature smoke due to thermal runaway. When the gas and particulate matter ejected from the battery come into contact with oxygen in the outside air at the same time, the battery pack will easily catch fire, and the excessive toxic gas in it will also pose a serious threat to human health. If the smoke emission is reduced, too much smoke will be blocked in the battery pack, which will easily cause the battery pack pressure to increase sharply, leading to thermal runaway and explosion accidents of the battery pack. Therefore, it is necessary to design a smoke adsorption device and match it with a suitable explosion-proof valve, which can not only adsorb particles to meet the smoke emission requirements, but also meet the battery pack pressure requirements.

[0004] Related technology - Patent name CN114843645A is battery thermal runaway smoke adsorption device, battery shell, battery and battery box, which provides a smoke treatment device with N adsorption tanks connected in series, and the device is installed outside the battery pack.

[0005] Related technology - The patent name of CN219873669U is a battery thermal runaway flue gas treatment system, which provides a battery thermal runaway flue gas treatment system with N control valves and adsorption tanks connected in parallel. The control valves of the flue gas adsorption device are opened separately according to different opening pressures to control the participation process of the adsorption tank.

[0006] The above-mentioned flue gas treatment systems all consist of multiple adsorption tanks arranged outside the battery pack, which places high demands on the space of the entire vehicle. Summary of the invention

[0007] One of the purposes of the present invention is to provide a battery pack smoke control device, a vehicle and a parameter design method to solve the problem of how to improve the smoke control effect of the battery pack without increasing the size of the battery pack.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A battery pack smoke control device comprises: a battery pack body; an explosion-proof valve arranged on the battery pack body; and a smoke adsorption device arranged in an airway of the battery pack body.

[0010] According to the above-mentioned technical means, the embodiments of the present invention can make full use of the airway space of the battery pack and place the smoke adsorption device inside the battery pack, thereby saving the layout space required for the smoke adsorption device and not occupying the external space of the battery. Thus, while making full use of the internal space of the battery pack, the volume of the battery pack can be effectively reduced compared to the battery with the smoke adsorption device arranged externally, so that the battery pack has the characteristics of flexible layout and strong versatility, and can be operated for different types of battery cells and various battery pack structures, and has high engineering application significance.

[0011] Furthermore, the smoke adsorption device is installed at at least one airway inlet in the battery pack body.

[0012] Furthermore, an adsorbent material is provided in the flue gas adsorption device.

[0013] Further, the adsorbent material is arranged in the air passage at the inlet of the explosion-proof valve.

[0014] Furthermore, the adsorbent material is a sheet-like structure.

[0015] Furthermore, the smoke adsorption device and the airway are cast into an integrated structure.

[0016] Furthermore, the filter size of the smoke adsorption device is less than or equal to the inner cavity size of the airway.

[0017] A vehicle comprises the above-mentioned battery pack smoke control device.

[0018] A parameter design method for a battery pack smoke control device, the method is used for parameter design of the above-mentioned battery pack, wherein the method includes: obtaining the flow area of ​​the erupting gas and the erupting particles of the battery pack in thermal runaway; constructing a three-dimensional simulation model of the battery pack according to the flow area of ​​the erupting gas and the erupting particles, wherein the three-dimensional simulation model includes the internal area of ​​the battery pack, the explosion-proof valve and the smoke adsorption device; simplifying the internal area of ​​the battery pack, the explosion-proof valve and the smoke adsorption device into the internal flow area of ​​the battery pack, the explosion-proof valve resistance source area and the smoke adsorption device resistance source area respectively; performing thermal runaway simulation according to the internal flow area, the explosion-proof valve resistance source area and the smoke adsorption device resistance source area, and determining the relevant parameters of the battery pack smoke control device finally designed according to the simulation results.

[0019] According to the above-mentioned technical means, the embodiments of the present invention can equivalently model the explosion-proof valve and smoke adsorption device with complex structure as a simple resistance source, so as to realize the rapid and repeated iteration of the thermal runaway analysis of the battery pack. It can not only quickly and accurately evaluate the pressure of the battery pack after thermal runaway, but also perform local smoke concentration evaluation, which has high engineering application significance, so that suitable explosion-proof valve and smoke adsorption device parameters can be positively designed, which can not only control the large amount of particulate matter ejected after the thermal runaway of the battery cell from being directly discharged into the atmosphere, but also ensure that the pressure of the battery pack is within the allowable range, thereby improving the fire safety of the battery pack and further reducing the number of thermal safety tests.

[0020] Furthermore, thermal runaway simulation is performed according to the internal flow area, the explosion-proof valve resistance source area and the smoke adsorption device resistance source area, including: obtaining the gas production rate function and gas production mass function of the battery pack as the thermal runaway reaction progresses, and the particle size distribution function of the particles ejected from the battery cell, and obtaining the first flow resistance function of the explosion-proof valve that varies with the flow rate, the second resistance coefficient function of the adsorbent that varies with the porosity, and the minimum particle size allowed to be filtered out by the smoke adsorption device; loading the gas production rate function, gas production mass function and particle size distribution function at the pressure relief port of the battery cell in the internal flow area, applying the first flow resistance function to the explosion-proof valve resistance source area, and applying the second resistance coefficient function and the minimum particle size to the smoke adsorption device resistance source area; after loading the currently designed smoke adsorption device parameters and explosion-proof valve parameters, calculating the gas velocity, pressure distribution and particle concentration distribution in the battery pack, and extracting the average pressure on the battery pack cover and the average concentration of particles at the battery pack discharge port.

[0021] According to the above technical means, the embodiment of the present invention can determine the correlation function of thermal runaway of the battery cell by testing the thermal runaway of the battery pack. Since the thermal runaway test data is the real performance data of the thermal runaway of the battery pack, the correlation function can be accurately generated based on the thermal runaway test data. At the same time, the resistance coefficient of the flow area of ​​the resistance source of the smoke adsorption device can be determined according to the test of the smoke adsorption device. Since the test can accurately determine the relevant data of the smoke adsorption device, the accuracy of the resistance coefficient can be improved, so that the resistance coefficient can accurately express the characteristics of the flow area of ​​the resistance source of the smoke adsorption device. At the same time, the minimum adsorbed particle size is obtained during the test process to improve the accuracy of subsequent simulations.

[0022] Furthermore, the relevant parameters of the battery pack smoke control device of the final design are determined according to the simulation results, including: identifying the average pressure of the battery pack cover and the average concentration of particulate matter at the battery pack outlet of the simulation results; if the average pressure of the battery pack cover and the average concentration of particulate matter at the battery pack outlet meet the target design requirements, the smoke adsorption device parameters and explosion-proof valve parameters of the current design are used as the smoke adsorption device parameters and explosion-proof valve parameters of the final design; if the average pressure of the battery pack cover and the average concentration of particulate matter at the battery pack outlet do not meet the target design requirements, the smoke adsorption device parameters and explosion-proof valve parameters are optimized, and the optimized smoke adsorption device parameters and explosion-proof valve parameters are used as the smoke adsorption device parameters and explosion-proof valve parameters of the current design.

[0023] According to the above-mentioned technical means, the embodiment of the present invention can determine whether the design parameters are qualified according to the simulated gas pressure and particle distribution, and iteratively update them according to the evaluation results, so as to positively design appropriate explosion-proof valve and smoke adsorption device parameters, which can not only control the large amount of particulate matter ejected after thermal runaway of the battery cell from being directly discharged into the atmosphere, but also ensure that the pressure of the battery pack is within the allowable range, thereby improving the fire safety of the battery pack and further reducing the number of thermal safety tests.

[0024] Furthermore, the resistance source region of the explosion-proof valve is a flow region in the shape of a cylinder, and the resistance source region of the smoke adsorption device is a flow region in the shape of a cuboid.

[0025] According to the above technical means, the embodiment of the present invention can simplify the explosion-proof valve resistance source area into a cylindrical flow area with an added resistance source. After that, the impact of the explosion-proof valve resistance on the pressure of the battery pack is completely dependent on the flow resistance characteristic parameters of the explosion-proof valve. Therefore, if the explosion-proof valve needs to be optimized, it is only necessary to adjust the model input parameters, and no modeling and meshing are required again to reduce the analysis time. Similarly, if the resistance source area of ​​the flue gas adsorption device is a rectangular flow area, if the analysis result does not meet the particulate matter emission requirements, it is only necessary to adjust the model input parameters, and no modeling and meshing are required again to reduce the analysis time.

[0026] Beneficial effects of the present invention:

[0027] (1) The embodiments of the present invention can make full use of the airway space of the battery pack and place the smoke adsorption device inside the battery pack, thereby saving the layout space required for the smoke adsorption device and eliminating the need to occupy additional external space of the battery. Thus, while making full use of the internal space of the battery pack, the volume of the battery pack can be effectively reduced compared to a battery with an external smoke adsorption device, so that the battery pack has the characteristics of flexible layout and strong versatility, and can be operated for different types of battery cells and various battery pack structures, and has high engineering application significance.

[0028] (2) The embodiments of the present invention can equivalently model the explosion-proof valve and smoke adsorption device with complex structures as a simple resistance source, thereby realizing rapid and repeated iteration of thermal runaway analysis of the battery pack. It can not only quickly and accurately evaluate the pressure of the battery pack after thermal runaway, but also evaluate the local smoke concentration, which has high engineering application significance. Therefore, it is possible to positively design appropriate explosion-proof valve and smoke adsorption device parameters, which can not only control the large amount of particulate matter ejected after thermal runaway of the battery cell from being directly discharged into the atmosphere, but also ensure that the pressure of the battery pack is within the allowable range, thereby improving the fire safety of the battery pack and further reducing the number of thermal safety tests.

[0029] (3) The embodiment of the present invention can determine the correlation function of thermal runaway of the battery cell by testing the thermal runaway of the battery pack. Since the thermal runaway test data is the real performance data of the thermal runaway of the battery pack, the correlation function can be accurately generated based on the thermal runaway test data. At the same time, the resistance coefficient of the flow area of ​​the resistance source of the smoke adsorption device can be determined according to the test of the smoke adsorption device. Since the test can accurately determine the relevant data of the smoke adsorption device, the accuracy of the resistance coefficient can be improved, so that the resistance coefficient can accurately express the characteristics of the flow area of ​​the resistance source of the smoke adsorption device. At the same time, the minimum adsorbed particle size is obtained during the test process to improve the accuracy of subsequent simulations.

[0030] (4) The embodiments of the present invention can determine whether the design parameters are qualified based on the simulated gas pressure and particle distribution, and iteratively update them based on the evaluation results, so as to positively design appropriate explosion-proof valve and smoke adsorption device parameters, which can not only control the large amount of particulate matter ejected after the thermal runaway of the battery cell from being directly discharged into the atmosphere, but also ensure that the pressure of the battery pack is within the allowable range, thereby improving the fire safety of the battery pack and further reducing the number of thermal safety tests.

[0031] (5) The embodiment of the present invention can simplify the explosion-proof valve resistance source area into a cylindrical flow area with an added resistance source. After that, the impact of the explosion-proof valve resistance on the pressure of the battery pack is completely dependent on the flow resistance characteristic parameters of the explosion-proof valve. Therefore, if the explosion-proof valve needs to be optimized, it is only necessary to adjust the model input parameters, and no modeling and meshing are required to be performed again, so as to reduce the analysis time. Similarly, if the resistance source area of ​​the flue gas adsorption device is a rectangular flow area, if the analysis result does not meet the particulate matter emission requirements, it is only necessary to adjust the model input parameters, and no modeling and meshing are required to be performed again, so as to reduce the analysis time.

[0032] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A block diagram of a battery pack smoke control device provided in an embodiment of the present invention;

[0034] Figure 2 A schematic diagram of the specific structure of a battery pack provided by an embodiment of the present invention;

[0035] Figure 3 A schematic diagram of the structure of a flue gas adsorption device provided in an embodiment of the present invention;

[0036] Figure 4 A flow chart of a parameter design method for a battery pack smoke control device provided in an embodiment of the present invention;

[0037] Figure 5 A schematic diagram of battery pack pressure provided by an embodiment of the present invention;

[0038] Figure 6 A diagram showing the calculation results of battery pack pressure and particulate matter concentration provided by an embodiment of the present invention;

[0039] Figure 7 A flow chart of an analysis method for controlling smoke emissions from a battery pack provided in an embodiment of the present invention;

[0040] Figure 8 A schematic diagram of particle size distribution at the inlet of an explosion-proof valve provided in an embodiment of the present invention.

[0041] Among them, there are adsorbent material-1, explosion-proof valve inlet-2, battery pack airway-3, battery module-4, battery pack base-5, airway inlet-6, battery cell pressure relief port-7, battery pack top cover-8, battery pack smoke control device 20, battery pack body-201, explosion-proof valve-202 and smoke adsorption device-203. DETAILED DESCRIPTION

[0042] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0043] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0044] Specifically, Figure 1A block diagram of a battery pack smoke control device provided in an embodiment of the present invention.

[0045] like Figure 1 As shown, the battery pack smoke control device 20 includes: a battery pack body 201 , an explosion-proof valve 202 and a smoke adsorption device 203 .

[0046] The explosion-proof valve 202 is disposed on the battery pack body 201 ; and the smoke adsorption device 203 is disposed in the air passage of the battery pack body 201 .

[0047] The battery pack body 201 can be understood as the battery pack shell. The battery pack body 201 is not only provided with multiple battery cells, such as a structure of hundreds of battery cells connected in series and parallel. From a safety perspective, in order to ensure that the design scheme meets the safety of thermal runaway of any battery cell, an air duct and an explosion-proof valve 202 are usually provided in the battery pack body 201. The air duct and the explosion-proof valve 202 are used to release pressure in time to reduce the probability of thermal runaway.

[0048] To this end, the embodiment of the present invention can make full use of the airway space of the battery pack body 201 and place the smoke adsorption device 203 inside the battery pack body 201, thereby saving the layout space required for the smoke adsorption device 203 and not occupying the external space of the battery pack body 201. Therefore, while making full use of the internal space of the battery pack, compared with the battery with the smoke adsorption device 203 arranged externally, the volume of the battery pack can be effectively reduced, so that the battery pack has the characteristics of flexible layout and strong versatility, and can be operated for different types of battery cells and various battery pack structures, and has high engineering application significance.

[0049] Specifically, if Figure 2 As shown, the battery pack may include a battery pack airway 3, a battery module 4, a battery pack base 5, an airway inlet 6, an explosion-proof valve 202, a smoke adsorption device 203, a battery cell pressure relief port 7 and a battery pack top cover 8, wherein the battery pack body 201 includes a battery pack base 5 and a battery pack top cover 8, and in order to better release pressure, the battery cell pressure relief port 7 is close to the explosion-proof valve 202.

[0050] Combination Figure 2 It can be seen that the embodiment of the present invention can make full use of the space of the battery pack air duct 3 and arrange the smoke adsorption device 203 in the space of the battery pack air duct 3 without increasing the volume of the battery pack. By making full use of the air duct space, the battery pack has the characteristics of flexible layout and strong versatility, and can be operated for different types of battery cells and various battery pack structures, which has high engineering application significance.

[0051] In the embodiment of the present invention, the smoke adsorption device 203 is installed at at least one airway inlet 6 in the battery pack body 201 .

[0052] It is understandable that the smoke adsorption device 203 and the battery pack airway 3 are not limited to a fixed installation method. Since the airway inlet 6 of the battery pack airway 3 can be set according to actual needs, for example, multiple airway inlets 6 can be set, it is not limited to installing the smoke adsorption device 203 at each airway inlet 6. Whether to install the smoke adsorption device 203 at each airway inlet 6 can be determined based on the airflow organization and adsorption effect in the battery pack, and is not specifically limited.

[0053] In the embodiment of the present invention, an adsorbent material 1 is provided in the flue gas adsorption device 203 , and the adsorbent material 1 is arranged in the air passage of the explosion-proof valve inlet 2 .

[0054] The number of layers of the adsorbent material may be specifically calibrated or set according to actual needs and circumstances, or may be specifically determined according to the methods in the following embodiments, without specific limitation.

[0055] It can be understood that the embodiments of the present invention can reasonably arrange the position and quantity of the adsorbent material according to the position and number of explosion-proof valves, the arrangement of the air ducts, etc. For example, if there is an air duct on only one side of the explosion-proof valve inlet, the adsorbent material is arranged on one side of the explosion-proof valve inlet; for another example, if there are air ducts on both sides of the explosion-proof valve inlet, the adsorbent material is arranged on both sides of the explosion-proof valve inlet; for another example, if there are air ducts on three sides of the explosion-proof valve inlet, the adsorbent material can be arranged on each side of the explosion-proof valve inlet. Therefore, by reasonably arranging the adsorbent material around the explosion-proof valve inlet, the gas near the explosion-proof valve inlet can be effectively adsorbed.

[0056] For example, Figure 3 As shown, the adsorbent material 1 may be arranged on both sides of the explosion-proof valve inlet 2 .

[0057] In the embodiment of the present invention, the adsorbent material of the flue gas adsorption device 203 is selected according to actual conditions without specific limitation. The adsorbent material of the flue gas adsorption device 203 can be basalt or glass fiber felt, with a material thickness of 2mm-3mm and a pore size generally less than 1000 microns.

[0058] In the embodiment of the present invention, the smoke adsorption device 203 and the air duct are cast into an integrated structure.

[0059] It is understandable that the smoke adsorption device 203 can be designed as an integrated structure with the battery pack air duct, and is arranged in the air ducts on both sides of the inlet position of the explosion-proof valve.

[0060] In the embodiment of the present invention, the filter size of the smoke adsorption device 203 is smaller than or equal to the inner cavity size of the airway.

[0061] It is understandable that the size of the flue gas adsorption device is determined according to the size of the battery pack, the characteristics of the battery cells and the adsorption effect, and is not specifically limited. Specifically: the filter size of the flue gas adsorption device can be consistent with the inner cavity of the battery pack airway, so that the gas in the airway can be filtered, so that the gas in the airway contacts the adsorbent material over a larger area, thereby improving the filtration efficiency. The filter size of the flue gas adsorption device can also be smaller than the inner cavity size of the airway. By reasonably setting the filter size, while satisfying most gas filtration requirements, a smaller filter size can save adsorbent materials, thereby saving the cost of the battery pack, and further reducing the manufacturing cost of the entire vehicle.

[0062] In the embodiment of the present invention, the adsorbent material may be a sheet-like structure.

[0063] It can be understood that the adsorbent material is stacked in sheets in the smoke adsorption device, and the number of stacked layers can be determined according to the parameter design method of the battery pack smoke control device in the following embodiments.

[0064] Next, a flow chart of a parameter design method for a battery pack smoke control device according to an embodiment of the present invention is described with reference to the accompanying drawings.

[0065] like Figure 4 As shown, the parameter design method of the battery pack smoke control device includes the following steps:

[0066] In step S101 , the flow area of ​​the erupting gas and the erupting particles due to thermal runaway of the battery pack is obtained.

[0067] It is understandable that by testing the thermal runaway of the battery pack, the flow area of ​​the erupting gas and particles of the battery pack during thermal runaway can be obtained. Therefore, the diffusion law inside the battery during thermal runaway of the battery pack can be analyzed, and the data under extreme conditions can be effectively monitored.

[0068] In step S102, a three-dimensional simulation model of the battery pack is constructed according to the flow area of ​​the erupting gas and the erupting particles, wherein the three-dimensional simulation model includes the internal area of ​​the battery pack, the explosion-proof valve and the smoke adsorption device.

[0069] It can be understood that the three-dimensional simulation model of the battery pack is constructed based on the flow area of ​​the erupting gas and particles, which includes three modules: the internal area of ​​the battery pack, the explosion-proof valve and the smoke adsorption device.

[0070] Specifically, the internal area of ​​the battery is the flow area surrounded by the battery pack cover, battery pack base, battery module and end plate of the battery module. The explosion-proof valve is composed of small parts such as waterproof and breathable film, sealing ring, moisture barrier and pressure spring. The smoke adsorption device is composed of porous media with complex pore structure.

[0071] In step S103, the internal area of ​​the battery pack, the explosion-proof valve and the smoke adsorption device are simplified into the internal flow area of ​​the battery pack, the resistance source area of ​​the explosion-proof valve and the resistance source area of ​​the smoke adsorption device respectively.

[0072] Among them, the resistance source area of ​​the explosion-proof valve is a flow area in the shape of a cylinder, and the resistance source area of ​​the smoke adsorption device is a flow area in the shape of a cuboid.

[0073] The three-dimensional simulation model constructed based on the flow area of ​​the erupting gas and particles is simplified as follows:

[0074] The explosion-proof valve not only has an extremely complex structure, but also has a narrow internal air gap. If the model is built according to the actual CAD (Computer Aided Design) dimensions, it will inevitably reduce work efficiency and increase the amount of calculation. Since we are only concerned with the overall resistance effect of the explosion-proof valve, this area can be simplified into a cylindrical flow area with an increased resistance source. After this area is simplified to a resistance source, the effect of the explosion-proof valve resistance on the pressure of the battery pack is completely dependent on the flow resistance characteristic parameters of the explosion-proof valve. Therefore, if the explosion-proof valve needs to be optimized, it is only necessary to adjust the model input parameters, and there is no need to re-model and mesh, so as to reduce analysis time.

[0075] The flue gas adsorption device is composed of porous media with complex pore structures. The same treatment method as the explosion-proof valve is used to simplify this area into a rectangular flow area with an increased resistance source. The difference is that due to the continuous adsorption of particle mass, the pores become less and more blocked, and the resistance characteristics of the resistance source are constantly changing according to the mass of the adsorbed particles, and there is an internal continuous iteration process. Similarly, if the analysis results do not meet the particulate emission requirements, only the model input parameters need to be adjusted, and there is no need to re-model and mesh, so as to reduce the analysis time.

[0076] In step S104, thermal runaway simulation is performed based on the internal flow area, the explosion-proof valve resistance source area and the smoke adsorption device resistance source area, and the relevant parameters of the battery pack smoke control device of the final design are determined based on the simulation results.

[0077] Among them, the relevant parameters of the battery pack smoke control device include smoke adsorption device parameters and explosion-proof valve parameters.

[0078] It can be understood that the embodiments of the present invention can calculate the gas pressure and particle distribution in the battery pack, then load the explosion-proof valve and the smoke adsorption device resistance source, update the calculation results of the pressure in the pack and the particle concentration; calculate the feedback of the pressure in the pack and the particle concentration at the explosion-proof valve position, and judge whether they are greater than the target value; when the calculated results of the pressure in the pack or the particle concentration at the explosion-proof valve position are unacceptable, adjust or optimize the design of the explosion-proof valve and the smoke adsorption device resistance source, and repeat the analysis again.

[0079] Among them, the entire battery pack is three-dimensionally modeled to examine the particle concentration and particle size distribution in key areas to assist in the optimization design. However, the explosion-proof valve and flue gas adsorption device are simplified as a resistance source. During the optimization iteration, there is no need for re-modeling and meshing. Only the input parameters need to be changed. It has the characteristics of high precision and rapid update.

[0080] In an embodiment of the present invention, a thermal runaway simulation is performed according to an internal flow area, an explosion-proof valve resistance source area, and a smoke adsorption device resistance source area, including: obtaining a gas production rate function and a gas production quality function of the battery pack as the progress of the thermal runaway reaction of the battery cell, and a particle size distribution function of the particles ejected from the battery cell, and obtaining a first flow resistance function of the explosion-proof valve that varies with the flow rate, a second resistance coefficient function of the explosion-proof valve adsorbent that varies with the porosity, and a minimum particle size that the smoke adsorption device allows to be filtered out; loading the gas production rate function, the gas production quality function, and the particle size distribution function at the pressure relief port of the battery cell in the internal flow area, applying the first flow resistance function and the second resistance coefficient function to the explosion-proof valve resistance source area, and applying the minimum particle size to the smoke adsorption device resistance source area; after loading the currently designed smoke adsorption device parameters and explosion-proof valve parameters, calculating the gas velocity and pressure distribution in the battery pack, and determining the average pressure on the battery pack cover and the average concentration of particles at the battery pack outlet according to the gas velocity and pressure distribution.

[0081] Among them, the parameters of the flue gas adsorption device include the pore size and stacking quantity of the adsorbent material.

[0082] It is understandable that thermal runaway simulation can be performed based on the simplified model. Since the simplified model is an equivalent modeling model of the explosion-proof valve and the flue gas adsorption device, the gas pressure and particle distribution after the thermal runaway of the battery pack can be quickly and accurately evaluated. Therefore, through the selection analysis of the resistance parameters of the battery pack explosion-proof valve and the pore size of the adsorbent material and the number of layers used, not only the adsorption of flue gas is considered to ensure that the gas coming out of the outlet is non-combustible, but also the gas pressure in the battery is within the design range, thereby improving the safety assessment of the battery pack.

[0083] Specifically, in the thermal runaway test of the battery cell, the parameters of gas production and particle emission are collected and fitted to generate the corresponding parameter fitting function. The fitting function includes: (1) the gas production rate function along with the progress of the thermal runaway reaction of the battery cell. The independent variable of the function is the progress of the thermal runaway reaction, and the dependent variable of the function is the gas production rate V; (2) the gas production mass function along with the progress of the thermal runaway reaction of the battery cell. The independent variable of the function is the progress of the thermal runaway reaction, and the dependent variable of the function is the gas production mass m; (3) the particle size distribution function of the particle emission of the battery cell. The independent variable of the function is the particle size, and the dependent variable of the function is the mass fraction Yd of particles larger than this diameter.

[0084] The explosion-proof valve resistance and flue gas adsorption device adsorption test and related parameters are obtained and fitted into the required functions, including: (1) the flow resistance function of the explosion-proof valve that changes with the flow rate, the independent variable of the function is the gas flow rate, and the dependent variable of the function is the flow resistance; (2) the resistance coefficient function of the explosion-proof valve adsorbent that changes with the porosity, the independent variable of the function is the porosity, and the dependent variable of the function is the resistance coefficient; (3) the pore size of the collector filter element is tested using a microscope, that is, the minimum particle size that it can filter out. Particles larger than this size will be adsorbed.

[0085] A battery pack is usually composed of hundreds of battery cells connected in series and parallel. In order to ensure that the design meets the safety of thermal runaway of any battery cell, the battery cell pressure relief port close to the front end of the flue gas adsorption device in the battery pack is selected as the gas and particulate matter emission port.

[0086] The gas mass function, gas velocity function and particle size distribution function of the battery cell are loaded at the battery cell pressure relief port, and the resistance characteristic parameters are loaded at the explosion-proof valve. The gas velocity and pressure distribution in the pack are calculated based on the gas continuity equation and Navier-Stokes equation. The particle concentration distribution in the battery pack is simulated and calculated based on the multiphase flow equation. Among them, the pressure in the battery pack is as follows: Figure 5 The particle concentration calculation results are shown in Figure 6 shown.

[0087] Therefore, according to the resistance coefficients of the explosion-proof valve resistance source and the smoke adsorption device, the gas pressure and particle distribution are updated. Since the flow area of ​​the explosion-proof valve resistance source and the flow area of ​​the smoke adsorption device resistance source have their own resistance coefficients, the impact of the explosion-proof valve resistance source and the smoke adsorption device resistance source on the thermal runaway of the battery pack can be accurately represented. Therefore, updating the gas pressure and particle distribution based on the respective resistance coefficients can effectively improve the accuracy of the thermal runaway simulation of the battery pack and the accuracy of the thermal runaway analysis results. Then, the resistance coefficient of the flow area of ​​the smoke adsorption device resistance source is determined according to the test of the smoke adsorption device. Since the test can accurately determine the relevant data of the smoke adsorption device, the accuracy of the resistance coefficient can be improved, so that the resistance coefficient can accurately express the characteristics of the flow area of ​​the smoke adsorption device resistance source. At the same time, the minimum adsorbed particle size is obtained during the test process to improve the accuracy of subsequent simulations.

[0088] In an embodiment of the present invention, the final designed flue gas adsorption device parameters and explosion-proof valve parameters are determined according to the simulation results, including: identifying the average pressure of the battery pack cover and the average concentration of particulate matter at the battery pack outlet of the simulation results; when the average pressure of the battery pack cover and the average concentration of particulate matter at the battery pack outlet meet the target design requirements, the currently designed flue gas adsorption device parameters and explosion-proof valve parameters are used as the final designed flue gas adsorption device parameters and explosion-proof valve parameters; when the average pressure of the battery pack cover and the average concentration of particulate matter at the battery pack outlet do not meet the target design requirements, the flue gas adsorption device parameters and explosion-proof valve parameters are optimized, and the optimized flue gas adsorption device parameters and explosion-proof valve parameters are used as the currently designed flue gas adsorption device parameters and explosion-proof valve parameters.

[0089] It is understandable that the target design requirement is the design pressure of the average pressure on the battery pack cover and the flammable concentration standard requirement for the average concentration of particulate matter at the battery pack outlet, which can be set according to actual conditions and no specific requirements are given here. In the embodiment of the present invention, the target design requirement is explained by taking the design pressure of 15kPa and the flammable concentration standard of the particulate matter concentration at the outlet as 0.5kg / m^3 as an example.

[0090] Specifically, the average pressure on the battery pack cover is as follows: Figure 5 As shown in Figure 2, the average concentration of particulate matter at the battery pack outlet is as follows: Figure 6 As shown in the figure, if all requirements are met, no optimization is required and the simulation ends. If the upper cover pressure exceeds the design pressure, such as 16kPa, or the particle concentration at the discharge port exceeds the combustible concentration standard, such as 0.6kg / m^3, the optimization phase will be entered.

[0091] Furthermore, if only the pressure inside the battery pack does not meet the requirements, you only need to adjust the explosion-proof valve parameter input part and recalculate to meet the requirements. If the particle concentration at the battery pack outlet does not meet the requirements, check the particle size distribution at the inlet of the explosion-proof valve and select the particle size with the largest volume share, such as Figure 8 The particle size of about 7.91um is shown as the pore size of the adsorbent. The adsorbent material is selected, and the amount of adsorbent material is continuously increased until the particle concentration at the battery pack outlet meets the requirements. When the amount of adsorbent material is continuously increased, the flow channel will gradually be blocked due to the continuous increase in the amount of adsorbent material and adsorbed particles, causing the pressure of the battery pack to continue to increase. When the pressure of the battery pack is too high to be acceptable, the explosion-proof valve resistance parameters need to be further adjusted until it is below the risk point.

[0092] According to the parameter design method of the battery pack smoke control device proposed in the embodiment of the present invention, the flow area of ​​the erupting gas and the erupting particles of the battery pack thermal runaway is obtained; the three-dimensional simulation model of the battery pack is constructed according to the flow area of ​​the erupting gas and the erupting particles, wherein the three-dimensional simulation model includes the internal area of ​​the battery pack, the explosion-proof valve and the smoke adsorption device; the internal area of ​​the battery pack, the explosion-proof valve and the smoke adsorption device are simplified into the internal flow area of ​​the battery pack, the explosion-proof valve resistance source area and the smoke adsorption device resistance source area; thermal runaway simulation is performed according to the internal flow area, the explosion-proof valve resistance source area and the smoke adsorption device resistance source area, and the smoke adsorption device parameters and the explosion-proof valve parameters of the final design are determined according to the simulation results. Through the above analysis method, the scheme can be optimized and the risk can be avoided before the thermal safety test of the battery pack, the number of thermal safety tests of the battery pack can be further reduced, the development cost can be reduced, and the forward design capability and risk assessment efficiency of the thermal safety of the battery pack can be improved. At the same time, the smoke adsorption device has a simple structure, flexible layout and strong versatility of the analysis method, and can be operated for different types of batteries and various battery pack structures, which has high engineering application significance.

[0093] The following will explain the parameter design method of the battery pack smoke control device through a specific implementation. Figure 7 As shown, the pore size selection and stacking quantity design method for the adsorbent material of the flue gas adsorption device includes:

[0094] S1. Thermal runaway test of battery cells. Collect and obtain gas production and ejection particle parameters and fit them to generate corresponding parameter fitting functions. The fitting functions include: (1) gas production rate function along with the progress of thermal runaway reaction of battery cells. The independent variable of the function is the progress of thermal runaway reaction, and the dependent variable of the function is gas production rate V; (2) gas production mass function along with the progress of thermal runaway reaction of battery cells. The independent variable of the function is the progress of thermal runaway reaction, and the dependent variable of the function is gas production mass m; (3) particle size distribution function of ejection particles of battery cells. The independent variable of the function is particle size, and the dependent variable of the function is mass fraction Yd of particles larger than this diameter.

[0095] The experiment takes the following steps: (1) Place the battery to be tested in the low-oxygen calorimetric chamber of a closed adiabatic accelerating calorimeter; (2) Heat the battery surface and track the temperature until the thermal runaway ends, and obtain real-time temperature and pressure change data; (3) According to the formula Calculate the gas production after thermal runaway of the battery cell, where P is the cavity pressure, V is the known cavity volume, n is the molar mass of the cavity gas, T is the cavity temperature, and R is the thermodynamic constant, which is equal to 8.314J / (mol K); (4) Collect the mass of particles ejected by thermal runaway of the battery cell, weigh them, and use a sample sieve and a particle size analyzer to obtain the particle size distribution of the particles ejected by the battery cell.

[0096] S2. Test the resistance of explosion-proof valve and adsorption of collector and obtain relevant parameters. Place the explosion-proof valve in a straight pipe, collect the flow data of the fluid entering and the inlet and outlet pressure of the explosion-proof valve, and obtain the flow resistance coefficient. Test the flue gas adsorption device. Load the particle flow into the straight pipe where the flue gas adsorption device is installed. Collect the mass and flow of the adsorbed particles and the inlet and outlet pressure data of the flue gas adsorption device and fit them into the corresponding function. The fitted function includes: (1) the flow resistance function of the explosion-proof valve that changes with the flow rate. The independent variable of the function is the gas flow rate and the dependent variable of the function is the flow resistance; (2) the resistance coefficient function of the explosion-proof valve adsorbent that changes with the porosity. The independent variable of the function is the porosity and the dependent variable of the function is the resistance coefficient; (3) Use a microscope to test the pore size of the collector filter element, that is, the minimum particle size that it can filter out. Particles larger than this size will be adsorbed.

[0097] S3. Construct a three-dimensional simulation model of the battery pack and simplify the model. Construct a three-dimensional simulation model according to the flow area of ​​the erupting gas and particles, such as Figure 2 As shown, it includes three modules: a battery pack internal flow area module, an explosion-proof valve 202 and a smoke adsorption device 203.

[0098] Furthermore, the internal flow area of ​​the battery is an area surrounded by the battery pack cover 8 , the battery pack base 5 , the battery module 4 and the end plate of the battery module 4 .

[0099] The explosion-proof valve 202 is composed of small parts such as a waterproof and breathable film, a sealing ring, a moisture-proof sheet and a pressure spring. Not only is the structure extremely complex, but the internal air gap is also narrow. If modeling is performed according to the actual CAD size, work efficiency will inevitably be reduced and the amount of calculation will be increased. Since we are only concerned about the overall resistance effect of the explosion-proof valve 202, this area can be simplified into a cylindrical flow area with an increased resistance source. After this area is simplified to a resistance source, the effect of the explosion-proof valve resistance on the pressure of the battery pack is completely dependent on the flow resistance characteristic parameters of the explosion-proof valve. Therefore, if the explosion-proof valve needs to be optimized, it is only necessary to adjust the model input parameters, and there is no need to re-model and mesh, which further reduces the analysis time.

[0100] The flue gas adsorption device 203 is composed of a porous medium with a complex pore structure. The same treatment method as the explosion-proof valve is used to simplify this area into a rectangular flow area with an increased resistance source. The difference is that due to the continuous adsorption of particle mass, the pores become less and more blocked, and the resistance characteristics of the resistance source are constantly changing according to the mass of the adsorbed particles, and there is an internal continuous iteration process. Similarly, if the analysis results do not meet the particulate emission requirements, only the input parameters in the model need to be adjusted, and there is no need to re-model and mesh, which further reduces the analysis time.

[0101] S4. Initialize the grid.

[0102] S5. Calculate the initial gas pressure and particle distribution in the battery pack.

[0103] Since a battery pack is usually composed of hundreds of battery cells connected in series and in parallel, in order to ensure that the design meets the safety of thermal runaway of any battery cell, a battery cell pressure relief port 7 close to the airway inlet 6 of the flue gas adsorption device in the battery pack is selected as the emission port for gas and particulate matter.

[0104] The gas production mass function, gas velocity function and particle size distribution function of the cell are loaded at the cell pressure relief port 7, and the resistance characteristic parameters are loaded at the explosion-proof valve 202. Among them, the particle size distribution at the inlet of the explosion-proof valve is as follows: Figure 8 shown.

[0105] The gas velocity and pressure distribution in the pack are calculated based on the gas continuity equation and Navier-Stokes equation. The particle concentration distribution in the battery pack is simulated and calculated based on the multiphase flow equation.

[0106] S6. Pressure and smoke concentration assessment.

[0107] Furthermore, the average pressure on the battery pack cover and the average concentration of particles at the battery pack outlet are extracted as follows: Figure 6 As shown in the figure, if all requirements are met, no optimization is required and the simulation ends. If the upper cover pressure exceeds the design pressure, such as 15kPa, or the particle concentration at the discharge port exceeds the combustible concentration standard, such as 0.5kg / m^3, the next optimization step will be entered.

[0108] S7. Optimization of pressure and smoke concentration inside the battery pack.

[0109] If only the pressure inside the battery pack does not meet the requirement, it is only necessary to adjust the parameter input part of the explosion-proof valve 202 and recalculate to meet the requirement.

[0110] If the particle concentration at the battery pack outlet does not meet the requirements, check the particle size distribution at the inlet of the explosion-proof valve and select the particle size with the largest volume share, such as Figure 8 The particle size of about 7.91um is shown as the pore size of the adsorbent. The adsorbent material is selected, and the amount of adsorbent material is continuously increased until the particle concentration at the battery pack outlet meets the requirements. When the amount of adsorbent material is continuously increased, the flow channel will gradually be blocked due to the continuous increase in the amount of adsorbent material and adsorbed particles, causing the battery pack pressure to continue to increase. When the battery pack pressure is too high to be acceptable, the explosion-proof valve resistance parameter needs to be further adjusted to below the risk point.

[0111] In summary, the embodiments of the present invention can perform three-dimensional modeling of the entire battery pack, examine the particle concentration and particle size distribution at key locations, and assist in optimizing the design. However, the method of simplifying the explosion-proof valve and the flue gas adsorption device into a resistance source does not require re-modeling and meshing during optimization iterations, but only requires changing the input parameters, which has the characteristics of high precision and rapid updating. The selection analysis of the resistance parameters of the battery pack explosion-proof valve and the pore size and number of layers of the adsorbent material not only considers the adsorption of flue gas to ensure that the gas coming out of the outlet is not combustible, but also takes into account that the air pressure in the battery is within the design range, thereby improving the safety assessment of the battery pack. The scheme can be optimized and risks can be avoided before the thermal safety test of the battery pack, thereby further reducing the number of thermal safety tests of the battery pack and reducing development costs.

[0112] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0113] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0114] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

[0115] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array, a field programmable gate array, etc.

[0116] A person skilled in the art may understand that all or part of the steps in the above-mentioned embodiment method may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0117] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A parameter design method for a battery pack smoke control device, characterized in that: The following steps are involved: Obtain the flow area of ​​the erupting gas and particles of the battery pack during thermal runaway; Constructing a three-dimensional simulation model of the battery pack according to the flow area of ​​the erupting gas and the erupting particles, wherein the three-dimensional simulation model includes an internal area of ​​the battery pack, an explosion-proof valve, and a smoke adsorption device; The internal area of ​​the battery pack, the explosion-proof valve and the smoke adsorption device are simplified into the internal flow area of ​​the battery pack, the resistance source area of ​​the explosion-proof valve and the resistance source area of ​​the smoke adsorption device respectively; Thermal runaway simulation is performed based on the internal flow area, the explosion-proof valve resistance source area and the smoke adsorption device resistance source area, and relevant parameters of the battery pack smoke control device in the final design are determined based on the simulation results.

2. The parameter design method of the battery pack smoke control device according to claim 1, characterized in that: The thermal runaway simulation is performed according to the internal flow area, the explosion-proof valve resistance source area and the smoke adsorption device resistance source area, including: Obtain the gas production rate function and gas production quality function of the battery pack as the progress of the thermal runaway reaction of the battery cell, as well as the particle size distribution function of the particles ejected from the battery cell, and obtain the first flow resistance function of the explosion-proof valve that changes with the flow rate, the second resistance coefficient function of the explosion-proof valve adsorbent that changes with the porosity, and the minimum particle size allowed to be filtered out by the smoke adsorption device; The gas production velocity function, the gas production mass function and the particle size distribution function are loaded on the battery cell pressure relief port in the internal flow area, the first flow resistance function and the second resistance coefficient function are applied to the explosion-proof valve resistance source area, and the minimum particle size is applied to the smoke adsorption device resistance source area; After loading the currently designed smoke adsorption device parameters and explosion-proof valve parameters, the gas velocity and pressure distribution in the battery pack are calculated, and the average pressure on the battery pack cover and the average concentration of particulate matter at the battery pack outlet are determined based on the gas velocity and pressure distribution.

3. The parameter design method of the battery pack smoke control device according to claim 2, characterized in that: The relevant parameters of the battery pack smoke control device finally designed are determined according to the simulation results, including: Identify the average pressure on the battery pack cover and the average concentration of particulate matter at the battery pack outlet of the simulation result; If the average pressure of the battery pack upper cover and the average concentration of particulate matter at the battery pack discharge port meet the target design requirements, the currently designed smoke adsorption device parameters and explosion-proof valve parameters are used as the final designed smoke adsorption device parameters and explosion-proof valve parameters; If the average pressure on the battery pack cover and the average concentration of particulate matter at the battery pack outlet do not meet the target design requirements, the smoke adsorption device parameters and the explosion-proof valve parameters are optimized, and the optimized smoke adsorption device parameters and the explosion-proof valve parameters are used as the smoke adsorption device parameters and the explosion-proof valve parameters of the current design.

4. The parameter design method of the battery pack smoke control device according to any one of claims 1 to 3, characterized in that: The resistance source area of ​​the explosion-proof valve is a flow area in the shape of a cylinder, and the resistance source area of ​​the smoke adsorption device is a flow area in the shape of a cuboid.

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