Thermal runaway safety design evaluation method, device, equipment and readable storage medium

Abstract

The present application discloses a thermal runaway safety design evaluation method, device, equipment and readable storage medium, including: performing a cell ARC test and a single cell thermal runaway test on a sample cell, and generating a cell thermal runaway temperature threshold parameter and a cell thermal runaway heat absorption threshold parameter based on the test results; determining a thermal runaway safety design criterion based on the cell thermal runaway temperature threshold parameter and the cell thermal runaway heat absorption threshold parameter; applying the sample cell to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data; and judging and determining a thermal runaway safety evaluation result for the system-level simplified module based on the thermal runaway safety design criterion and the system-level thermal runaway data. The present application does not require actual testing at the whole package level, which significantly shortens the evaluation cycle, reduces evaluation costs, and improves evaluation test flexibility.

Description

Technical Field

[0001] The present application relates to the field of battery testing, and more specifically, to a thermal runaway safety design evaluation method, device, equipment and readable storage medium. Background Art

[0002] With the popularity of electric vehicles and the growth of market demand, the safety performance of battery systems has received increasing attention, among which battery system thermal runaway is one of the focus issues in the current electric vehicle safety field. The design of battery thermal runaway performance is directly related to the safety of the battery system and its vehicles and personnel.

[0003] Since the thermal runaway process involves complex processes such as electrochemical combustion, and safety protection involves many aspects such as basic performance parameters of battery cells and module insulation, a more accurate and efficient evaluation method is needed. However, in the current battery system development and design stage, due to the lack of effective indicators and evaluation methods for measuring system thermal runaway safety, the industry generally relies on whole package experimental testing for evaluation and judgment, but it has several obvious defects.

[0004] First, the design and development of battery systems involves multiple parts such as electrical and structural parts. When preparing thermal runaway sample packs, many structural parts need to be specially molded. This not only increases the cost of sample molds, but also increases the cost of overall testing.

[0005] Second, since the whole package experimental test requires a complete battery system sample package, the entire cycle from design to preparation to testing is relatively long, which is not conducive to rapid iteration and optimization of design solutions, and prolongs the project development time.

[0006] Third, during the R&D and design process, if the thermal runaway test of the entire package fails to meet the requirements, the design team needs to re-optimize the design plan and re-prepare and test the sample package, which will increase additional costs and development and testing time.

[0007] Based on this, the present application provides a more efficient and accurate thermal runaway safety design evaluation scheme, which can avoid the above-mentioned deficiencies of the prior art. Summary of the invention

[0008] In view of this, the present application provides a thermal runaway safety design evaluation method, device, equipment and readable storage medium. By introducing cell-level thermal runaway safety design criteria and system-level simplified thermal runaway module thermal analysis, thermal runaway safety design evaluation is performed. There is no need to conduct actual measurements at the whole package level, which significantly shortens the evaluation cycle, reduces evaluation costs, and improves the flexibility of evaluation testing.

[0009] A thermal runaway safety design evaluation method, comprising:

[0010] Perform cell ARC test and single cell thermal runaway test on sample cells, and generate cell thermal runaway temperature threshold parameters and cell thermal runaway heat absorption threshold parameters based on the test results;

[0011] Determining a thermal runaway safety design criterion based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter;

[0012] Applying the sample battery cell to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data;

[0013] According to the thermal runaway safety design criterion and the system-level thermal runaway data, a thermal runaway safety assessment result of the system-level simplified module is determined.

[0014] Optionally, perform a cell ARC test and a single cell thermal runaway test on the sample cell, and generate a cell thermal runaway temperature threshold parameter and a cell thermal runaway heat absorption threshold parameter based on the test results, including:

[0015] Configuring a thermal runaway temperature collection point of the sample battery cell inside the sample battery cell;

[0016] Performing a thermal runaway test on the sample battery cell using an ARC test device, and determining a thermal runaway temperature threshold parameter of the battery cell according to a thermal runaway trigger temperature collected from the thermal runaway temperature collection point of the sample battery cell during the thermal runaway test;

[0017] Setting the restraint force, explosion-proof valve opening and thermal insulation material for the single-cell thermal runaway test of the sample cell in accordance with the restraint force setting requirements, explosion-proof valve opening setting requirements and thermal insulation material setting requirements;

[0018] A single-cell thermal runaway test is performed on the sample battery cell, and the battery cell thermal runaway heat absorption threshold parameters are calculated based on the heating plate temperature rise, insulation material temperature rise and fixture temperature rise obtained in the test.

[0019] Optionally, configuring a thermal runaway temperature collection point of the sample battery cell inside the sample battery cell includes:

[0020] If the cell structure type of the sample cell is a single-wound core cell, the thermal runaway temperature collection point is located at the center of the single-wound core;

[0021] If the cell structure type of the sample cell is a double-wound core cell, the thermal runaway temperature collection point is located at the center of the two winding cores;

[0022] If the cell structure type of the sample cell is a laminated structure, the thermal runaway temperature collection point is located at the center of the laminate in the half thickness direction.

[0023] Optionally, the constraint force setting requirement is:

[0024]

[0025] Where F is the restraint force of the single cell module, F max It is the maximum restraint that the battery system module can withstand at the end of life EOL stage; F min It is the minimum restraint force required by the battery system module in the BOL stage at the beginning of its life;

[0026] The explosion-proof valve opening setting requirements are:

[0027]

[0028] Among them, S is the opening area of ​​the explosion-proof valve, S ex is the area of ​​the explosion-proof valve of the battery cell, λ is the correction coefficient of the opening area, and λ is 1.2~1.8;

[0029] The insulation material setting requirements:

[0030]

[0031] Where d is the width of the air layer that constitutes the thermal insulation material, W max is the upper limit of the module thickness assembly tolerance, μ is the air layer gap correction coefficient, and μ is set between 1.2 and 1.5.

[0032] Optionally, the threshold parameters of the thermal runaway heat absorption of the battery cell are calculated based on the temperature rise of the heater, the temperature rise of the insulation material, and the temperature rise of the fixture obtained through testing, including:

[0033] The heating plate temperature rise is obtained according to the test data, and the heating plate mass and the specific heat capacity are combined to calculate the heating plate heat absorption threshold;

[0034] The heat absorption threshold of the thermal insulation material is calculated based on the temperature rise of the thermal insulation material obtained through the test data and the mass and specific heat capacity of the thermal insulation material;

[0035] The fixture heat absorption threshold is calculated based on the fixture temperature rise obtained from the test data and the fixture mass and fixture specific heat capacity.

[0036] The heating input heat is calculated based on the rated power, heating time and heating efficiency of the heating plate;

[0037] The thermal runaway heat absorption threshold parameter of the battery cell is determined according to the heating input heat, the heating plate heat absorption threshold, the insulation material heat absorption threshold and the fixture heat absorption threshold.

[0038] Optionally, based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter, determining a thermal runaway safety design criterion includes:

[0039] Generate a first safety design criterion according to the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway temperature safety factor;

[0040] generating a second safety design criterion according to the battery cell thermal runaway heat absorption threshold parameter and the battery cell thermal runaway heat absorption energy safety factor;

[0041] The first safety design criterion and the second safety design criterion are combined to generate a thermal runaway safety design criterion.

[0042] Optionally, the system-level simplified module includes an explosion-proof valve, a heat-conducting material, a liquid cooling plate, and a battery cell module;

[0043] The cell module is fixed by clamps at both ends, and includes a heating plate and a plurality of sample cells, wherein each of the sample cells is separated by a heat insulating material, and the heating plate is arranged between the clamp at one end of the cell module and the sample cells;

[0044] The sample cell is applied to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data, including:

[0045] Heating the heating plate triggers thermal runaway of the first sample battery cell starting from one side of the heating plate, and obtains the side temperature of the first sample battery cell close to the heating plate and the amount of heat absorbed by the first sample battery cell;

[0046] When the first sample battery cell reaches thermal runaway, obtaining a net heat flux of the second sample battery cell starting from one side of the heating plate;

[0047] System-level thermal runaway data is generated based on the net heat flux of the second sample battery cell, the side temperature of the first sample battery cell close to the heating plate, and the amount of heat absorbed by the first sample battery cell.

[0048] A thermal runaway safety design evaluation device, comprising:

[0049] A threshold parameter generating unit is used to perform a cell ARC test and a single cell thermal runaway test on a sample cell, and generate a cell thermal runaway temperature threshold parameter and a cell thermal runaway heat absorption threshold parameter according to the test results;

[0050] A safety criterion determination unit, configured to determine a thermal runaway safety design criterion based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter;

[0051] A system-level analysis unit, used for applying the sample battery cell to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data;

[0052] The safety design evaluation unit is used to determine the thermal runaway safety evaluation result of the system-level simplified module according to the thermal runaway safety design criterion and the system-level thermal runaway data.

[0053] A thermal runaway safety design evaluation device, comprising a memory and a processor;

[0054] The memory is used to store programs;

[0055] The processor is used to execute the program to implement each step of the thermal runaway safety design evaluation method as described in any one of the above items.

[0056] A readable storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, each step of the thermal runaway safety design evaluation method as described in any one of the above items is implemented.

[0057] It can be seen from the above technical solutions that the thermal runaway safety design evaluation method, device, equipment and readable storage medium provided in the embodiments of the present application first perform a cell ARC test and a single cell thermal runaway test on the sample cell, and generate the cell thermal runaway temperature threshold parameters and the cell thermal runaway heat absorption threshold parameters according to the test results. Then, based on the cell thermal runaway temperature threshold parameters and the cell thermal runaway heat absorption threshold parameters, the thermal runaway safety design criteria are determined. The system-level thermal runaway data is obtained by applying the sample cell to a pre-designed system-level simplified module for thermal analysis. Finally, based on the thermal runaway safety design criteria and the system-level thermal runaway data, the thermal runaway safety assessment result of the system-level simplified module is determined.

[0058] On the one hand, the present application proposes a basis for judging thermal runaway at the cell level based on the basic temperature parameters of thermal runaway of the battery cell and its heat transfer characteristics, that is, a thermal runaway safety design criterion generated based on the temperature threshold and heat absorption threshold obtained by using the battery cell ARC test and the single-cell thermal runaway test, which can achieve an accurate evaluation of the thermal runaway safety performance of the battery system. On the other hand, the present application provides a system simplified module design method and a thermal analysis scheme, which maps the thermal runaway criterion at the cell level to the system simplified module evaluation design, and can quickly obtain preliminary pre-evaluation data without the need for actual measurement at the whole package level, and can achieve an early and accurate evaluation and judgment of the thermal runaway safety design scheme of the entire system in the design and development stage, thereby reducing the evaluation cost and shortening the evaluation cycle. In addition, since there is no need to conduct whole package experimental testing, the design team can adjust and optimize the design scheme more flexibly, and the present application has higher evaluation flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0060] Figure 1 A flow chart of a thermal runaway safety design evaluation method disclosed in an embodiment of the present application;

[0061] Figure 2 A schematic diagram of thermal runaway temperature collection points corresponding to different wound core battery structures disclosed in an embodiment of the present application;

[0062] Figure 3 A schematic diagram of the structure of a single-cell thermal runaway test device disclosed in an embodiment of the present application;

[0063] Figure 4 A schematic diagram of the structure of a system-level simplified module disclosed in an embodiment of the present application;

[0064] Figure 5 A schematic diagram of the structure of a cell module in a system-level simplified module disclosed in an embodiment of the present application;

[0065] Figure 6 A schematic diagram of a thermal runaway safety design evaluation device disclosed in an embodiment of the present application;

[0066] Figure 7 A schematic diagram of cell-level ARC test data disclosed in an embodiment of the present application;

[0067] Figure 8 A schematic diagram of a cell-level thermal runaway heat absorption data disclosed in an embodiment of the present application;

[0068] Fig. 9 A schematic diagram of a simplified module disclosed in an embodiment of the present application, showing the temperature and net heat data of a cell adjacent to a target cell;

[0069] Fig.10 A schematic diagram of a system-level simplified module core temperature cloud map data disclosed in an embodiment of the present application;

[0070] Fig.11 A schematic diagram of a whole package thermal runaway test solution disclosed in an embodiment of the present application;

[0071] Fig.12 A schematic diagram of test results of a whole package thermal runaway test disclosed in an embodiment of the present application;

[0072] Fig.13This is a hardware structure block diagram of a thermal runaway safety design evaluation device disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0073] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0074] An embodiment of the present application provides a thermal runaway safety design evaluation method, which can be applied to a system or platform for thermal runaway simulation of a battery, and can also be applied to various computer terminals or smart terminals. The execution subject can be a processor or server of the computer terminal or smart terminal.

[0075] Next, the present application scheme is introduced. The present application proposes the following technical scheme, please see below for details.

[0076] Figure 1 This is a flow chart of a thermal runaway safety design evaluation method disclosed in an embodiment of the present application.

[0077] like Figure 1 As shown, the method may include:

[0078] Step S1, performing a cell ARC test and a single cell thermal runaway test on a sample cell, and generating a cell thermal runaway temperature threshold parameter and a cell thermal runaway heat absorption threshold parameter according to the test results.

[0079] Specifically, the sample cells are subjected to the cell ARC test (adiabatic accelerated calorimeter test) and the single cell thermal runaway test to evaluate the thermal safety performance of the cells, generate the cell thermal runaway temperature threshold parameters and the cell thermal runaway heat absorption threshold parameters, and provide key data support for the safety performance evaluation of the cells. The goal of the cell ARC test is to determine the cell thermal runaway trigger temperature parameter, which is used as the key temperature threshold to measure whether the cell has thermal runaway. Through the precise cell thermal runaway trigger temperature parameter, a clear temperature limit can be set for the thermal runaway behavior of the cell.

[0080] The goal of the single-cell level thermal runaway test is to obtain the threshold value of the amount of heat absorbed by the cell during the thermal runaway process. Since the thermal runaway test at the whole package system level usually adopts an external heating solution, that is, using an external heat source to heat a specific cell to induce thermal runaway, the cell will gradually absorb heat during the heating process. When the absorbed heat reaches a certain threshold, thermal runaway will be triggered inside the cell. Therefore, the threshold value of the amount of heat absorbed by the cell has become an important basis for judging whether the cell is about to experience thermal runaway.

[0081] Based on the above test results, the present invention can finally obtain the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter, and use these two parameters to jointly determine the thermal runaway safety design criterion to improve the overall reliability. However, how to obtain the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter through experimental design is particularly important.

[0082] Step S2: determining a thermal runaway safety design criterion based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter.

[0083] Specifically, based on the cell thermal runaway temperature threshold parameter and the heat absorption threshold parameter, the thermal runaway safety design criterion can be determined. First, based on the cell thermal runaway temperature threshold parameter (i.e., the thermal runaway trigger temperature inside the cell) and the set cell thermal runaway temperature safety factor μ, the first safety design criterion, i.e., the cell thermal runaway large surface center temperature T max Should meet , where T limit is the temperature threshold parameter of thermal runaway of the battery cell. Secondly, according to the heat absorption threshold parameter of thermal runaway of the battery cell (i.e., the net heat absorption Q absorption threshold value of the thermal runaway process of the battery cell) and the energy safety factor of the thermal runaway heat absorption of the battery cell , the second safety design criterion is generated, that is, the net heat absorption Q of the battery cell during thermal runaway should satisfy , where Q limit is the heat absorption threshold parameter of the battery cell for thermal runaway. Finally, these two safety design criteria are combined to form a complete thermal runaway safety design criterion, that is, and conditions to ensure the rationality and reliability of thermal runaway safety design.

[0084] In other words, the process of determining the thermal runaway safety design criteria may specifically include:

[0085] ① Generate a first safety design criterion according to the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway temperature safety factor;

[0086] ② Generate a second safety design criterion according to the battery cell thermal runaway heat absorption threshold parameter and the battery cell thermal runaway heat absorption energy safety factor;

[0087] ③ Combining the first safety design criterion and the second safety design criterion to generate a thermal runaway safety design criterion.

[0088] Step S3: Apply the sample battery cell to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data.

[0089] Specifically, the sample battery cells are applied to a pre-designed system-level simplified module for in-depth thermal analysis. The system-level simplified module includes components such as explosion-proof valves, battery cell modules, thermal conductive materials, and liquid cooling plates, and has been insulated according to actual needs. By placing the sample battery cells in this module, its thermal behavior in a real working environment can be simulated. During the thermal analysis process, advanced thermal simulation technology is used to obtain system-level thermal runaway data at the system level. The system-level thermal runaway data includes but is not limited to the temperature distribution of the battery cells, heat transfer conditions, and potential thermal runaway diffusion trends. By analyzing the system-level thermal runaway data, it is possible to evaluate whether the thermal insulation design of the current system is effective enough to prevent the further spread of thermal runaway events.

[0090] Step S4: judging and determining a thermal runaway safety assessment result of the system-level simplified module according to the thermal runaway safety design criterion and the system-level thermal runaway data.

[0091] Specifically, based on the previously determined thermal runaway safety design criteria and the thermal runaway data obtained through thermal analysis of the system-level simplified module, a comprehensive evaluation of the thermal runaway safety performance of the system-level simplified module was conducted, including a comparative analysis of the actual thermal runaway data with the temperature threshold and heat absorption threshold in the thermal runaway safety design criteria. If the temperature and heat absorption data obtained by the system-level simplified module during the thermal analysis process meet or exceed the standards in the design criteria, that is, they both meet and If the conditions are met, then it can be determined that the thermal runaway safety design of the module is qualified, that is, the thermal runaway safety assessment result of the system-level simplified module is qualified, which can effectively prevent the spread of thermal runaway events. On the contrary, if the actual data exceeds the range of the design criteria, it means that the thermal runaway safety assessment result of the system-level simplified module is unqualified, then the thermal insulation design of the system needs to be re-optimized to ensure that it can meet the thermal runaway safety requirements.

[0092] It can be seen from the above technical solutions that the thermal runaway safety design evaluation method, device, equipment and readable storage medium provided in the embodiments of the present application first perform a cell ARC test and a single cell thermal runaway test on the sample cell, and generate the cell thermal runaway temperature threshold parameters and the cell thermal runaway heat absorption threshold parameters according to the test results. Then, based on the cell thermal runaway temperature threshold parameters and the cell thermal runaway heat absorption threshold parameters, the thermal runaway safety design criteria are determined. The system-level thermal runaway data is obtained by applying the sample cell to a pre-designed system-level simplified module for thermal analysis. Finally, based on the thermal runaway safety design criteria and the system-level thermal runaway data, the thermal runaway safety assessment result of the system-level simplified module is determined.

[0093] On the one hand, the present application proposes a basis for judging thermal runaway at the cell level based on the basic temperature parameters of thermal runaway of the battery cell and its heat transfer characteristics, that is, a thermal runaway safety design criterion generated based on the temperature threshold and heat absorption threshold obtained by using the battery cell ARC test and the single-cell thermal runaway test, which can achieve an accurate evaluation of the thermal runaway safety performance of the battery system. On the other hand, the present application provides a system simplified module design method and a thermal analysis scheme, which maps the thermal runaway criterion at the cell level to the system simplified module evaluation design, and can quickly obtain preliminary pre-evaluation data without the need for actual measurement at the whole package level, and can achieve an early and accurate evaluation and judgment of the thermal runaway safety design scheme of the entire system in the design and development stage, thereby reducing the evaluation cost and shortening the evaluation cycle. In addition, since there is no need to conduct whole package experimental testing, the design team can adjust and optimize the design scheme more flexibly, and the present application has higher evaluation flexibility.

[0094] In some embodiments of the present application, the process of step S1, performing a cell ARC test and a single cell thermal runaway test on a sample cell, and generating a cell thermal runaway temperature threshold parameter and a cell thermal runaway heat absorption threshold parameter according to the test results is introduced, which may specifically include:

[0095] Step S11, determining a thermal runaway temperature collection point of the sample battery cell.

[0096] Specifically, the selection of thermal runaway temperature collection points directly affects the accuracy and reliability of subsequent thermal runaway test data. Compared with the prior art, the temperature collection points are set outside the battery cell, such as the large surface (the side with the largest area), side, or pole of the shell. In this application, the temperature collection points are set inside the battery cell, that is, inside the battery cell shell. Compared with the outside of the battery cell, setting the temperature collection points inside the battery cell can improve the overall evaluation standards and improve the reliability of the thermal runaway installation design evaluation. The specific reasons are explained in detail below.

[0097] Furthermore, the thermal runaway temperature collection point of the sample battery cell can be configured inside the sample battery cell. Different types of battery cells, such as single-wound core battery cells, double-wound core battery cells or laminated structure battery cells, have different internal heat distribution and transfer methods. Therefore, in order to make the collected temperature more accurately reflect the internal temperature changes of the battery cell during the thermal runaway process, different locations of the thermal runaway temperature collection points are set for battery cells of different structural types. The following method for determining the thermal runaway temperature collection point is provided in the present application, but it can be understood that the present application should not be limited to the battery cell structure types and selection methods provided below.

[0098] In specific implementation, the layout of the thermal runaway temperature collection points will vary according to the different structural types of the battery cells. Figure 2As shown, for a single-core battery cell, the thermal runaway temperature collection point is arranged at the center of the core to ensure that the temperature changes inside the battery cell can be accurately captured. For a dual-core battery cell, it is necessary to arrange the thermal runaway temperature collection point at the center of the two cores to comprehensively monitor the thermal runaway conditions of the two cores. For laminated structure batteries, the thermal runaway temperature collection point is arranged at the center of the laminate in the thickness direction to reflect the internal temperature changes of the laminated structure battery cell during the thermal runaway process. Therefore, configuring the thermal runaway temperature collection point of the sample battery cell inside the sample battery cell may include:

[0099] If the cell structure type of the sample cell is a single-wound core cell, the thermal runaway temperature collection point is located at the center of the single-wound core;

[0100] If the cell structure type of the sample cell is a double-wound core cell, the thermal runaway temperature collection point is located at the center of the two winding cores;

[0101] If the cell structure type of the sample cell is a laminated structure, the thermal runaway temperature collection point is located at the center of the laminate in the half thickness direction.

[0102] Step S12: Perform a thermal runaway test on the sample battery cell using an ARC test device, and determine a thermal runaway temperature threshold parameter of the battery cell according to a thermal runaway trigger temperature collected from the thermal runaway temperature collection point of the sample battery cell during the thermal runaway test.

[0103] Specifically, the ARC test (adiabatic accelerating calorimeter) is used to evaluate the key characteristic temperatures and related thermodynamic parameters of lithium-ion batteries during thermal runaway. The test can accurately measure the self-generated heat and heat generation rate of the battery during thermal runaway by precisely controlling the sample temperature and the heating chamber temperature and keeping them consistent before reaching the thermal runaway trigger temperature. This application uses the ARC (adiabatic accelerating calorimeter) test equipment to perform thermal runaway tests on sample cells, and determines the thermal runaway temperature threshold parameters of the cell based on the thermal runaway trigger temperature collected from the thermal runaway temperature collection point.

[0104] In the process of thermal runaway testing of the sample battery cells using the ARC test equipment, three important characteristic temperatures of thermal runaway of lithium-ion batteries can be obtained: T1 (self-heating temperature), T2 (thermal runaway triggering temperature) and T3 (maximum internal temperature of thermal runaway). Among them, T1 marks the beginning of self-heating of the battery, which is usually due to the melting of SEI (solid electrolyte interface) on the surface of the battery's negative electrode material, causing the electrolyte to react with the negative electrode material. For current lithium-ion batteries, the temperature range of T1 is usually between 60 and 120°C. At this stage, the voltage of the battery will decrease.

[0105] As the temperature continues to rise, when the internal temperature of the battery reaches about 200°C, the ceramic-coated diaphragm will shrink in a closed-cell manner, causing local contact between the positive and negative electrodes inside the battery and a micro-short circuit. This micro-short circuit will further aggravate the self-heating of the battery and promote the overall shrinkage and disintegration of the diaphragm. When the temperature exceeds 200°C, the shrinkage rate of the diaphragm increases significantly, and the positive and negative electrodes inside the battery are in contact with a large range, causing a large-scale internal short circuit. At this time, the heat generated by the internal short circuit and side reactions will further accelerate the disintegration of the diaphragm, and the battery voltage will quickly drop to 0V in a very short time (such as within 60 seconds).

[0106] Finally, when the internal temperature of the battery reaches T2, the battery goes into thermal runaway. At this stage, the temperature rise rate inside the battery rises sharply, exceeding 1°C / s, and the internal temperature of the battery soars from T2 to T3 in an instant. The internal materials of the battery undergo a high-temperature oxidation-reduction reaction, generating a large amount of flammable mixed gas (such as CH4, CO, H2, C2H4, etc.). At the same time, the positive and negative electrode materials and aluminum foil of the battery melt at high temperatures. When the internal pressure of the battery reaches the pressure relief safety pressure of the safety valve, an eruption will occur at the battery safety valve position.

[0107] It should be noted that, since the battery cell generates internal heat after the T1 point, the heat of the temperature in the thermal runaway triggering process of the battery cell comes from the internal self-generation of heat and external heating. The internal temperature is higher than the temperature transferred to the inside by the external heating, so it is more reasonable for T2 to be the internal temperature of the battery cell. At the same time, the applicant found that when the temperature collection point is set on the side of the battery cell (non-center position), when an eruption occurs, the temperature collection point position does not have an opening during the thermal runaway process due to the tensile effect of the high-temperature resistant sealing glue, but a large amount of explosive and combustible mixed gas, high-temperature flue gas particles and copper foil fragments will still be ejected from the eruption port, and the T2 value cannot be accurately detected. Therefore, the position setting of the temperature collection point inside the battery cell is equally important. In this application, the temperature collection point is set at the center of the battery cell, which greatly improves the accuracy of T2 temperature collection, thereby improving the accuracy of the overall thermal runaway assessment method.

[0108] During the test, it is necessary to focus on monitoring the temperature change at point T2 and determine the thermal runaway temperature threshold parameter T of the battery cell based on the test results. limit =T2.

[0109] Step S13, setting the restraint force, explosion-proof valve opening and thermal insulation material for the single-cell thermal runaway test applied to the sample cell according to the restraint force setting requirements, explosion-proof valve opening setting requirements and thermal insulation material setting requirements.

[0110] Specifically, the test conditions for the single-cell thermal runaway test mainly include the setting of the restraint force, the setting of the explosion-proof valve opening, and the reasonable arrangement of the thermal insulation materials. In this level of testing, the main goal is to obtain the threshold value of the heat absorption during the thermal runaway process of the battery cell. Since the thermal runaway test at the whole package system level usually relies on an external heating scheme, that is, using an external heat source to heat the target battery cell to trigger thermal runaway, the battery cell will gradually absorb heat during the heating process. When the absorbed heat reaches a certain threshold, thermal runaway will occur inside the battery cell. Therefore, the threshold parameter of the heat absorption of the battery cell during thermal runaway becomes an important basis for judging whether thermal runaway will occur.

[0111] like Figure 3 As shown, in the single-cell thermal runaway test device, one side of the sample cell is attached to the insulation material, and the other side is attached to the heating plate. The area of ​​the heating plate needs to be less than or equal to the side area of ​​the cell to avoid dry burning and heating efficiency. The other side of the heating plate is the same insulation material, which mainly blocks the heat transfer from the heating plate to the direction of the fixture. The insulation material includes an insulation pad. Specifically, the insulation pad can be silicone foam to play a buffering and heat-insulating role. The insulation pad is arranged on the side of the sample cell away from the heating plate, and is also arranged on the side of the heating plate away from the sample cell. The left and right clamps are connected by at least two bolts and screws to provide a restraining force in the thickness direction of the cell. Since the test results of the thermal runaway performance of the cell are related to the external restraining force it is subjected to, the relationship between the bolt torque and the restraining force is:

[0112]

[0113] Among them, F is the restraint force of the single cell module, N is the number of screws, M is the bolt torque, k is the preload coefficient, and the galvanized bolt is 0.18, d s is the nominal diameter of the bolt.

[0114] The binding force setting requirements are:

[0115]

[0116] Where F is the restraint force of the single cell module, F max It is the maximum restraint that the battery system module can withstand at the end of life EOL stage; F min It is the minimum restraint force required for the battery system module in the BOL stage at the beginning of its life.

[0117] F max It is set by comprehensively considering the upper tolerance size of the battery cells when they are grouped and the restraint required at the end-of-life EOL stage (due to the attenuation of the battery cells, their thickness will increase), and the value is usually in the range of 25~30KN. minIt is set by comprehensively considering the lower limit tolerance size of the battery cells when grouped and the restraint requirements in the BOL stage at the beginning of life (also taking into account that the thickness of the battery cells may increase due to attenuation), and the general value range is 1.2~3KN. The setting of the restraint force has an important impact on the thermal runaway performance of the battery cells. If the restraint force is too small, the battery cells will expand freely during the heating process, which may cause the battery cell shell to crack, and then trigger thermal runaway. If the restraint force is too large, the thickness of the battery cell will be squeezed to a greater extent. When heated, it is completely restricted, and the shrinkage space of the diaphragm in the thickness direction becomes limited, resulting in a more intense thermal runaway process and a shortened initiation time. Therefore, the restraint force must be controlled within a reasonable range of battery cell grouping. Exceeding this range will cause a large deviation between the module test results and the system-level design, thereby weakening the guiding significance of the evaluation.

[0118] At the same time, the entire module needs to be covered with thermal insulation cotton to reduce the heat dissipation of the module, and an injection port, i.e., the explosion-proof valve opening, needs to be opened at the corresponding position of the thermal insulation cotton and the battery cell explosion-proof valve. The requirements for the explosion-proof valve opening are:

[0119]

[0120] Among them, S is the opening area of ​​the explosion-proof valve, S ex is the area of ​​the explosion-proof valve of the battery cell, λ is the correction coefficient of the opening area, and λ is taken as 1.2~1.8.

[0121] This design is mainly based on the ejection state of the battery cell when it is in thermal runaway, because the heat generated by thermal runaway is mainly ejected from the battery cell explosion-proof valve area and dissipated in a trumpet shape. If the explosion-proof valve opening is designed to be too small, the heat may be transferred to other large surfaces of the module, interfering with the accuracy of the temperature collection data; and if the explosion-proof valve opening is designed to be too large, the heat exchange area between the module and the external environment will increase, resulting in a lower test value.

[0122] like Figure 3 As shown, in order to achieve better insulation effect, a closed air layer needs to be reserved between the module and the insulation cotton to avoid heat transfer and heat dissipation deviation caused by lamination. The insulation material also includes an air layer, and the air layer setting requirements are:

[0123]

[0124] Where d is the width of the air layer that constitutes the thermal insulation material, that is, the gap distance between the fixture and the thermal insulation cotton, W max is the upper limit of the module thickness assembly tolerance, μ is the air layer gap correction coefficient, and μ is set between 1.2 and 1.5.

[0125] In addition, considering the differences in materials and performance of different cell types (such as LFP and NCM), the thickness of the thermal insulation cotton should also be selected differently when conducting cell testing. For LFP cell modules, due to their low thickness thermal conductivity and low self-generated heat, the thickness of the thermal insulation cotton can be selected to be 0.8~2.5mm; while for NCM cell modules, due to their relatively high thermal conductivity and heat generation, the thickness of the thermal insulation cotton is recommended to be 3~5mm. The main function of the thermal insulation cotton is to isolate the test module from the external environment to ensure the accuracy and reliability of the test results.

[0126] Step S14, performing a single-cell thermal runaway test on the sample battery cell, and calculating the battery cell thermal runaway heat absorption threshold parameter based on the heating plate temperature rise, the insulation material temperature rise, and the fixture temperature rise obtained in the test.

[0127] Specifically, after the setup is completed, a single-cell thermal runaway test can be conducted on the sample battery cell. This requires not only accurate recording of the temperature rise of the heater, insulation material, and fixture during the test, but also calculation of the heat absorption threshold parameter for thermal runaway of the battery cell based on these data. The specific process is as follows:

[0128] ①According to the temperature rise of the heater obtained by the test, combined with the mass of the heater and the specific heat capacity of the heater, the heat absorption threshold of the heater is calculated;

[0129] ②According to the temperature rise of the insulation material obtained from the test, combined with the mass of the insulation material and the specific heat capacity of the insulation material, the heat absorption threshold of the insulation material is calculated;

[0130] ③According to the temperature rise of the fixture obtained by the test, combined with the fixture mass and fixture specific heat capacity, the fixture heat absorption threshold is calculated;

[0131] ④ Calculate the heating input heat according to the rated power, heating time and heating efficiency of the heating plate;

[0132] ⑤ According to the heating input heat, the heating plate heat absorption threshold, the insulation material heat absorption threshold and the fixture heat absorption threshold, determine the cell thermal runaway heat absorption threshold parameter .

[0133] In order to accurately measure the heat absorbed by various components such as insulation materials and fixtures during the heating process, at least three temperature sensors need to be arranged to calculate the heat absorption threshold before the thermal runaway of a single battery cell is triggered, that is, the safety limit of thermal runaway. This calculation process can be expressed as:

[0134]

[0135] Where P is the rated power of the heater, t is the heating time, is the heating efficiency, c i is the specific heat capacity of each component, mi For the quality of each component, The temperature rise of each component.

[0136] It should be noted that since the outside of the test module is wrapped with thermal insulation material (i.e. the aforementioned thermal insulation cotton), the heat exchange between the module and the external environment can be ignored, thereby simplifying the overall method and improving accuracy. At the same time, the applicant found that the thermal insulation pad and the fixture on the non-heating side absorbed less heat during the heating process. Therefore, when calculating the heat absorbed by the battery cell, the above theoretical formula can be used to ensure overall accuracy. In addition, since there is a temperature gradient in the test module along the thickness direction of the thermal pad and the fixture between the battery cells, it is necessary to perform an interpolation function fitting calculation based on the temperature point data on both sides of the thickness direction, such as the least squares method, to more accurately calculate the temperature and heat absorption of other components.

[0137] According to this test plan, the relationship between the temperature and time changes of different components of the module can be obtained. Under the condition that its mass and specific heat capacity parameters are known, the temperature and time curves of each component are integrated to obtain the heat absorption of each component. According to the principle of conservation of energy, the heat absorption energy of the battery cell itself can be obtained by subtracting the heat absorption of each component from the total heating. During the test, the judgment standard for the thermal runaway trigger cutoff condition is that the temperature rise rate of the temperature point on the non-heating surface of the battery cell reaches or exceeds 1°C / s.

[0138] In some embodiments of the present application, a system level simplified module is introduced.

[0139] like Figure 4 and Figure 5 As shown, the system-level simplified modules include explosion-proof valves, thermal conductive materials, liquid cooling plates, and battery cell modules;

[0140] The cell module is fixed by clamps at both ends, and comprises a heating plate and a plurality of sample cells, wherein each of the sample cells is separated by a heat insulating material, and the heating plate is arranged between the clamp at one end of the cell module and the sample cells.

[0141] Specifically, after obtaining the thermal runaway threshold criterion parameters at the cell level, a system-level simplified module solution was designed to evaluate whether the system insulation design meets the current thermal runaway safety requirements. The solution includes explosion-proof valves, cell modules, thermal conductive materials, and liquid cooling plates. At the same time, thermal insulation treatment is implemented, and it is ensured that there are at least two temperature monitoring points. In order to maintain the consistency of the solution evaluation, the heating plate power and the clamp restraint force are consistent with the thermal runaway at the single cell level. The effective spatial volume of the cell module must meet specific conditions, that is, the module volume is equal to the net volume of the system (the volume of the battery pack frame minus the volume of all components), and the net volume of the system is equal to the volume of the entire pack minus the sum of the volumes of all components.

[0142] Based on the established system-level simplified model, thermal simulation is used to monitor the thermal behavior of the sample battery cells. Figure 5 As shown in the figure, during the simulation, the No. 1 sample cell was detonated as a thermal runaway cell, and the maximum temperature and net heat absorption on the side of the No. 2 sample cell were monitored at the same time, and the rationality of the design was judged by the simulation data. In order to ensure the accuracy of the evaluation of the simplified module solution at the system level, the conditions affecting heat transfer, such as thermal conductive materials, thermal insulation materials, restraint force, and net volume, were kept consistent in the simulation.

[0143] On this basis, step S3, applying the sample battery cell to a pre-designed system-level simplified module for thermal analysis, and obtaining system-level thermal runaway data may further include:

[0144] Step S31, heating by the heating plate triggers thermal runaway of the first sample battery cell starting from one side of the heating plate, and obtains the side temperature of the first sample battery cell close to the heating plate and the amount of heat absorbed by the first sample battery cell.

[0145] Step S32, when the first sample battery cell reaches thermal runaway, obtaining a net heat flux of the second sample battery cell starting from one side of the heating plate;

[0146] Step S33: Generate system-level thermal runaway data based on the net heat flux of the second sample cell, the side temperature of the first sample cell close to the heating plate, and the amount of heat absorbed by the first sample cell.

[0147] Specifically, when performing thermal analysis, the first sample cell is first heated using a heating plate to trigger thermal runaway from one side of the heating plate. In this process, the temperature data of the side of the first sample cell and the amount of heat absorbed during the thermal runaway process are obtained. Next, when the first sample cell reaches a thermal runaway state, the net heat flux of the second sample cell immediately behind it is obtained. The net heat flux of the cell refers to the heat transferred by the cell through heat conduction, convection, and radiation during the thermal runaway process. The acquisition of this data helps to understand the speed and intensity of the propagation of thermal runaway between cells, thereby evaluating the thermal insulation effect and thermal runaway suppression capability of the simplified module at the system level. Finally, based on the data of the net heat flux of the second sample cell, the temperature of the side of the first sample cell, and the amount of heat absorbed by the first sample cell, the system-level thermal runaway data is comprehensively generated. These data not only include the temperature changes and heat absorption of the cell during the thermal runaway process, but also reflect the propagation characteristics of thermal runaway between cells. Through in-depth analysis of these data, the thermal runaway safety performance of simplified modules at the system level can be accurately evaluated, providing strong support for subsequent design optimization.

[0148] For example, for Figure 5The system-level simplified module corresponding to the cell module is used for thermal runaway safety assessment. In the simulation analysis, when cell 1 triggers thermal runaway, the process from the start of heating to the moment when cell 1 triggers thermal runaway is monitored based on the principle of heat transfer, and the net heat absorption of cell 2 between the two moments at the system level is calculated, that is, the maximum side temperature T of cell 2 close to the heating plate at this time is obtained. max2 and the net heat absorption Q2, and then compare it with the thermal threshold at the cell level to evaluate the rationality of the thermal runaway safety design. If the temperature and heat criteria of cell 2 meet the preset conditions at the same time, that is, they meet the and If the conditions are met, it is considered that the current system-level simplified module can prevent heat spread, and the thermal runaway safety assessment result is qualified.

[0149] At this time, the net heat absorbed by the battery cell No. 2 is Specifically, the first sample battery cell reaches thermal runaway, with the maximum side temperature of battery cell No. 1 being T max1 Reaching the cell thermal runaway temperature threshold parameter T limit , or the net heat absorption Q1 of cell 1 reaches the heat absorption threshold parameter Q of the cell for thermal runaway limit It should be noted that during the ARC test, the cell generates heat internally, so the temperature inside the cell is higher than the surface temperature of the cell. The thermal runaway test uses a heating trigger method, where heat is transferred from the heating plate to the inside of the cell through the side of the cell. During the heating process, the surface temperature of the side of the cell will be higher than the temperature inside the cell (thermal simulation cannot take into account electrochemical heat generation). The external temperature is used as a judgment during the simulation, that is, when the outer surface temperature reaches T limit It is believed that thermal runaway has been triggered. In fact, the internal temperature of the battery cell will be lower than the surface temperature at this time, which is consistent with the simulation logic, ensuring the design safety margin and being more conservative during simulation.

[0150] Since there are occasional factors in the actual test of thermal runaway, such as differences in cell consistency and differences in module composition preparation, there may be some uncertainties. Therefore, if only one parameter is used as the judgment threshold, reliability cannot be guaranteed. At the same time, the applicant found that the thermal runaway temperature is mainly caused by the internal insulation of the cell reaching its melting point during the external heating and the heat generation of the cell itself, which causes the temperature change inside the cell; the heat absorption is based on the dimensions of the external heat (target battery heat transfer) absorbed by all the components of the cell, including electrolyte, positive and negative electrode materials, and internal electrochemical heat generation. There is no clear correlation between the two. By defining the thermal runaway results of the cell through two non-correlated parameters, the installation design margin can be improved to avoid the problem of using only one parameter or two related parameters as the basis for judgment.

[0151] A thermal runaway safety design evaluation device provided in an embodiment of the present application is described below. The thermal runaway safety design evaluation device described below and the thermal runaway safety design evaluation method described above can refer to each other.

[0152] See also Figure 6 , Figure 6 A schematic diagram of a thermal runaway safety design evaluation device disclosed in an embodiment of the present application.

[0153] like Figure 6 As shown, the thermal runaway safety design evaluation device may include:

[0154] The threshold parameter generating unit 110 is used to perform a cell ARC test and a single cell thermal runaway test on the sample cell, and generate a cell thermal runaway temperature threshold parameter and a cell thermal runaway heat absorption threshold parameter according to the test results;

[0155] A safety criterion determination unit 120, configured to determine a thermal runaway safety design criterion based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter;

[0156] A system-level analysis unit 130, configured to apply the sample battery cell to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data;

[0157] The safety design evaluation unit 140 is used to judge and determine the thermal runaway safety evaluation result of the system-level simplified module according to the thermal runaway safety design criterion and the system-level thermal runaway data. It can be seen from the above technical scheme that a thermal runaway safety design evaluation method, device, equipment and readable storage medium provided in the embodiment of the present application first perform a cell ARC test and a single cell thermal runaway test on the sample battery cell, and generate a battery cell thermal runaway temperature threshold parameter and a battery cell thermal runaway heat absorption threshold parameter according to the test results. Then, based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter, the thermal runaway safety design criterion is determined. The system-level thermal runaway data is obtained by applying the sample battery cell to a pre-designed system-level simplified module for thermal analysis. Finally, based on the thermal runaway safety design criterion and the system-level thermal runaway data, the thermal runaway safety evaluation result of the system-level simplified module is judged and determined.

[0158] On the one hand, the present application proposes a basis for judging thermal runaway at the cell level based on the basic temperature parameters of thermal runaway of the battery cell and its heat transfer characteristics, that is, a thermal runaway safety design criterion generated based on the temperature threshold and heat absorption threshold obtained by using the battery cell ARC test and the single-cell thermal runaway test, which can achieve an accurate evaluation of the thermal runaway safety performance of the battery system. On the other hand, the present application provides a system simplified module design method and a thermal analysis scheme, which maps the thermal runaway criterion at the cell level to the system simplified module evaluation design, and can quickly obtain preliminary pre-evaluation data without the need for actual measurement at the whole package level, and can achieve an early and accurate evaluation and judgment of the thermal runaway safety design scheme of the entire system in the design and development stage, thereby reducing the evaluation cost and shortening the evaluation cycle. In addition, since there is no need to conduct whole package experimental testing, the design team can adjust and optimize the design scheme more flexibly, and the present application has higher evaluation flexibility.

[0159] Optionally, the threshold parameter generating unit performs a cell ARC test and a single cell thermal runaway test on a sample cell, and generates a cell thermal runaway temperature threshold parameter and a cell thermal runaway heat absorption threshold parameter according to the test results, which may include:

[0160] Configuring a thermal runaway temperature collection point of the sample battery cell inside the sample battery cell;

[0161] Performing a thermal runaway test on the sample battery cell using an ARC test device, and determining a thermal runaway temperature threshold parameter of the battery cell according to a thermal runaway trigger temperature collected from the thermal runaway temperature collection point of the sample battery cell during the thermal runaway test;

[0162] Setting the restraint force, explosion-proof valve opening and thermal insulation material for the single-cell thermal runaway test of the sample cell in accordance with the restraint force setting requirements, explosion-proof valve opening setting requirements and thermal insulation material setting requirements;

[0163] A single-cell thermal runaway test is performed on the sample battery cell, and the battery cell thermal runaway heat absorption threshold parameters are calculated based on the heating plate temperature rise, insulation material temperature rise and fixture temperature rise obtained in the test.

[0164] Optionally, the threshold parameter generating unit may configure the thermal runaway temperature collection point of the sample battery cell inside the sample battery cell, which may include:

[0165] If the cell structure type of the sample cell is a single-wound core cell, the thermal runaway temperature collection point is located at the center of the single-wound core;

[0166] If the cell structure type of the sample cell is a double-wound core cell, the thermal runaway temperature collection point is located at the center of the two winding cores;

[0167] If the cell structure type of the sample cell is a laminated structure, the thermal runaway temperature collection point is located at the center of the laminate in the half thickness direction.

[0168] Optionally, the constraint force setting requirement is:

[0169]

[0170] Where F is the restraint force of the single cell module, F max It is the maximum restraint that the battery system module can withstand at the end of life EOL stage; F min It is the minimum restraint force required by the battery system module in the BOL stage at the beginning of its life;

[0171] The explosion-proof valve opening setting requirements are:

[0172]

[0173] Among them, S is the opening area of ​​the explosion-proof valve, S ex is the area of ​​the explosion-proof valve of the battery cell, λ is the correction coefficient of the opening area, and λ is 1.2~1.8;

[0174] The insulation material setting requirements:

[0175]

[0176] Where d is the width of the air layer that constitutes the thermal insulation material, W max is the upper limit of the module thickness assembly tolerance, μ is the air layer gap correction coefficient, and μ is set between 1.2 and 1.5.

[0177] Optionally, the threshold parameter generating unit performs a process of calculating the cell thermal runaway heat absorption threshold parameter based on the heating plate temperature rise, the insulation material temperature rise, and the fixture temperature rise obtained through test collection, which may include:

[0178] The heating plate temperature rise is obtained according to the test data, and the heating plate mass and the specific heat capacity are combined to calculate the heating plate heat absorption threshold;

[0179] The heat absorption threshold of the thermal insulation material is calculated based on the temperature rise of the thermal insulation material obtained through the test data and the mass and specific heat capacity of the thermal insulation material;

[0180] The fixture heat absorption threshold is calculated based on the fixture temperature rise obtained from the test data and the fixture mass and fixture specific heat capacity.

[0181] The heating input heat is calculated based on the rated power, heating time and heating efficiency of the heating plate;

[0182] The thermal runaway heat absorption threshold parameter of the battery cell is determined according to the heating input heat, the heating plate heat absorption threshold, the insulation material heat absorption threshold and the fixture heat absorption threshold.

[0183] Optionally, the safety criterion determination unit determines the thermal runaway safety design criterion based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter, which may include:

[0184] Generate a first safety design criterion according to the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway temperature safety factor;

[0185] generating a second safety design criterion according to the battery cell thermal runaway heat absorption threshold parameter and the battery cell thermal runaway heat absorption energy safety factor;

[0186] The first safety design criterion and the second safety design criterion are combined to generate a thermal runaway safety design criterion.

[0187] Optionally, the system-level simplified module includes an explosion-proof valve, a heat-conducting material, a liquid cooling plate, and a battery cell module;

[0188] The cell module is fixed by clamps at both ends, and includes a heating plate and a plurality of sample cells, wherein each of the sample cells is separated by a heat insulating material, and the heating plate is arranged between the clamp at one end of the cell module and the sample cells;

[0189] The process in which the system-level analysis unit applies the sample battery cell to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data may include:

[0190] Heating the heating plate triggers thermal runaway of the first sample battery cell starting from one side of the heating plate, and collecting the side temperature of the first sample battery cell and the amount of heat absorbed by the first sample battery cell in real time;

[0191] When the first sample battery cell reaches thermal runaway, monitoring the net heat flux of the second sample battery cell starting from one side of the heating plate;

[0192] System-level thermal runaway data is generated based on the net heat flux of the second sample battery cell, the side temperature of the first sample battery cell, and the heat absorbed by the first sample battery cell.

[0193] The present application is further described and demonstrated by an example below.

[0194] Take the thermal runaway safety design assessment of a project as an example. First, perform the cell ARC test and single cell thermal runaway test according to step S1, and you can get the following: Figure 7 The cell-level ARC test data shown in the figure and Figure 8 The cell-level thermal runaway heat absorption data shown is used to determine the cell thermal runaway temperature threshold parameters and the cell thermal runaway heat absorption threshold parameters.

[0195] Secondly, thermal analysis is performed based on the pre-designed system-level simplified module. By monitoring the temperature and its heat data through thermal simulation, the temperature and net heat data of the cells adjacent to the simplified module and the target cell can be obtained, such as Fig. 9 As shown, it can be further generated as Fig.10 The system-level simplified module cell temperature cloud data is shown.

[0196] From the above data curve, it can be seen that under the current system-level thermal runaway design scheme, when the target cell (i.e. cell 1) thermally runs away, the maximum temperature of the adjacent cell (i.e. cell 2) is T max Less than the thermal runaway judgment threshold , and the net heat absorption , indicating that the system-level thermal runaway design will not cause thermal runaway propagation.

[0197] Finally, in order to verify whether the solution involved in the present invention can ensure the thermal runaway safety of the whole package, Fig.11 As shown in the figure, the above structural design was used to carry out a thermal runaway simulation test at the battery pack level. At this time, the No. 7 battery cell was the target battery cell, and the test results were as follows: Fig.12 As shown, no thermal runaway occurred. The specific actual test plan for the whole package is as follows:

[0198] 1) Battery: 168Ah;

[0199] 2) SOC: ≥95%;

[0200] 3) Full container: 1P112S;

[0201] 4) Heating plate: 1000W;

[0202] 5) Trigger point location: middle cell;

[0203] 6) Module restraint force: 6kN;

[0204] 7) Thermal management mode: open cycle without cooling.

[0205] Comprehensive Fig.13 The whole package test results shown can illustrate that by adopting a thermal runaway safety assessment and its structural device involved in the present invention, adopting the test module design scheme provided by this scheme, combined with the thermal runaway safety design criteria, through the system simplified module thermal simulation results, the system-level thermal runaway safety design assessment can be performed in the design and development stage, and the final whole package thermal runaway actual measurement results also prove the rationality of the scheme and module structure provided by this scheme.

[0206] The thermal runaway safety design evaluation device provided in the embodiment of the present application can be applied to thermal runaway safety design evaluation equipment. Fig.13 The hardware structure diagram of the thermal runaway safety design evaluation equipment is shown in FIG. Fig.13 ,The hardware structure of the thermal runaway safety design evaluation device may include: at least one processor 1, at least one communication interface 2, at least one memory 3 and at least one communication bus 4;

[0207] In the embodiment of the present application, the number of the processor 1, the communication interface 2, the memory 3, and the communication bus 4 is at least one, and the processor 1, the communication interface 2, and the memory 3 communicate with each other through the communication bus 4;

[0208] The processor 1 may be a central processing unit CPU, or an application-specific integrated circuit ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present invention, etc.;

[0209] The memory 3 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), etc., such as at least one disk memory;

[0210] The memory stores a program, and the processor can call the program stored in the memory, wherein the program is used to:

[0211] Perform cell ARC test and single cell thermal runaway test on sample cells, and generate cell thermal runaway temperature threshold parameters and cell thermal runaway heat absorption threshold parameters based on the test results;

[0212] Determining a thermal runaway safety design criterion based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter;

[0213] Applying the sample battery cell to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data;

[0214] According to the thermal runaway safety design criterion and the system-level thermal runaway data, a thermal runaway safety assessment result of the system-level simplified module is determined.

[0215] Optionally, the detailed functions and extended functions of the program may refer to the above description.

[0216] The embodiment of the present application further provides a readable storage medium, which may store a program suitable for execution by a processor, wherein the program is used to:

[0217] Perform cell ARC test and single cell thermal runaway test on sample cells, and generate cell thermal runaway temperature threshold parameters and cell thermal runaway heat absorption threshold parameters based on the test results;

[0218] Determining a thermal runaway safety design criterion based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter;

[0219] Applying the sample battery cell to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data;

[0220] According to the thermal runaway safety design criterion and the system-level thermal runaway data, a thermal runaway safety assessment result of the system-level simplified module is determined.

[0221] Optionally, the detailed functions and extended functions of the program may refer to the above description.

[0222] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0223] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0224] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A thermal runaway safety design evaluation method, characterized in that: include: Perform cell ARC test and single cell thermal runaway test on sample cells, and generate cell thermal runaway temperature threshold parameters and cell thermal runaway heat absorption threshold parameters based on the test results; Based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter, determining a thermal runaway safety design criterion, including: generating a first safety design criterion according to the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway temperature safety factor; generating a second safety design criterion according to the battery cell thermal runaway heat absorption threshold parameter and the battery cell thermal runaway heat absorption energy safety factor; combining the first safety design criterion and the second safety design criterion to generate a thermal runaway safety design criterion, wherein the thermal runaway safety design criterion satisfies both T max ≤T limit *μ and Q≤Q limit *ζ, where T max The center temperature of the large surface of the battery cell during thermal runaway, T limit is the thermal runaway temperature threshold parameter of the battery cell, μ is the thermal runaway temperature safety factor of the battery cell, Q is the net heat absorbed during the thermal runaway process of the battery cell, Q limit is the threshold parameter of the heat absorption of the battery cell during thermal runaway, ζ is the energy safety factor of the heat absorption of the battery cell during thermal runaway; The sample battery cell is applied to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data, wherein the system-level simplified module includes an explosion-proof valve, a heat-conducting material, a liquid cooling plate, and a battery cell module; the battery cell module is fixed by clamps at both ends, and includes a heating plate and a battery cell module of a plurality of the sample batteries, wherein each of the sample batteries is separated by a heat-insulating material, and the heating plate is arranged between the clamp and the sample battery cell at one end of the battery cell module; the first sample battery cell starting from one side of the heating plate is triggered to thermal runaway by heating with the heating plate, and the side temperature of the first sample battery cell close to the heating plate and the amount of heat absorbed by the first sample battery cell are obtained; when the first sample battery cell reaches thermal runaway, the net heat flux of the second sample battery cell starting from one side of the heating plate is obtained; based on the net heat flux of the second sample battery cell, the side temperature of the first sample battery cell close to the heating plate, and the amount of heat absorbed by the first sample battery cell, the system-level thermal runaway data is generated; According to the thermal runaway safety design criterion and the system-level thermal runaway data, a thermal runaway safety assessment result of the system-level simplified module is determined.

2. The method according to claim 1, characterized in that Perform cell ARC test and single cell thermal runaway test on sample cells, and generate cell thermal runaway temperature threshold parameters and cell thermal runaway heat absorption threshold parameters based on the test results, including: Configuring a thermal runaway temperature collection point of the sample battery cell inside the sample battery cell; Performing a thermal runaway test on the sample battery cell using an ARC test device, and determining a thermal runaway temperature threshold parameter of the battery cell according to a thermal runaway trigger temperature collected from the thermal runaway temperature collection point of the sample battery cell during the thermal runaway test; Setting the restraint force, explosion-proof valve opening and thermal insulation material for the single-cell thermal runaway test of the sample cell in accordance with the restraint force setting requirements, explosion-proof valve opening setting requirements and thermal insulation material setting requirements; A single-cell thermal runaway test is performed on the sample battery cell, and the battery cell thermal runaway heat absorption threshold parameters are calculated based on the heating plate temperature rise, insulation material temperature rise and fixture temperature rise obtained in the test.

3. The method according to claim 2, characterized in that Configuring a thermal runaway temperature collection point of the sample battery cell inside the sample battery cell includes: If the cell structure type of the sample cell is a single-wound core cell, the thermal runaway temperature collection point is located at the center of the single-wound core; If the cell structure type of the sample cell is a double-wound core cell, the thermal runaway temperature collection point is located at the center of the two winding cores; If the cell structure type of the sample cell is a laminated structure, the thermal runaway temperature collection point is located at the center of the laminate in the half thickness direction.

4. The method according to claim 2, characterized in that: The binding force setting requirements are: F max ≥F≥F min ; Where F is the restraint force of the single cell module, F max It is the maximum restraint that the battery system module can withstand at the end of life EOL stage; F min It is the minimum restraint force required by the battery system module in the BOL stage at the beginning of its life; The explosion-proof valve opening setting requirements are: S=S ex *l; Among them, S is the opening area of ​​the explosion-proof valve, S ex is the area of ​​the explosion-proof valve of the battery cell, λ is the correction coefficient of the opening area, and λ is 1.2~1.8; The insulation material setting requirements: d=W max +μ*0.25; Where d is the width of the air layer that constitutes the thermal insulation material, W max is the upper limit of the module thickness assembly tolerance, μ is the air layer gap correction coefficient, and μ is set between 1.2 and 1.

5.

5. The method according to claim 2, characterized in that: The threshold parameters of the thermal runaway heat absorption of the battery cell are calculated based on the temperature rise of the heater, the temperature rise of the insulation material, and the temperature rise of the fixture, including: The heating plate temperature rise is obtained according to the test data, and the heating plate mass and the specific heat capacity are combined to calculate the heating plate heat absorption threshold; The heat absorption threshold of the thermal insulation material is calculated based on the temperature rise of the thermal insulation material obtained through the test data and the mass and specific heat capacity of the thermal insulation material; The fixture heat absorption threshold is calculated based on the fixture temperature rise obtained from the test data and the fixture mass and fixture specific heat capacity. The heating input heat is calculated based on the rated power, heating time and heating efficiency of the heating plate; The thermal runaway heat absorption threshold parameter of the battery cell is determined according to the heating input heat, the heating plate heat absorption threshold, the insulation material heat absorption threshold and the fixture heat absorption threshold.

6. A thermal runaway safety design evaluation device, characterized in that: include: A threshold parameter generating unit is used to perform a cell ARC test and a single cell thermal runaway test on a sample cell, and generate a cell thermal runaway temperature threshold parameter and a cell thermal runaway heat absorption threshold parameter according to the test results; A safety criterion determination unit, configured to determine a thermal runaway safety design criterion based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter; A system-level analysis unit, used for applying the sample battery cell to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data; A safety design evaluation unit, configured to determine a thermal runaway safety evaluation result of the system-level simplified module according to the thermal runaway safety design criterion and the system-level thermal runaway data; Based on the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway heat absorption threshold parameter, a thermal runaway safety design criterion is determined, including: Generate a first safety design criterion according to the battery cell thermal runaway temperature threshold parameter and the battery cell thermal runaway temperature safety factor; generating a second safety design criterion according to the battery cell thermal runaway heat absorption threshold parameter and the battery cell thermal runaway heat absorption energy safety factor; Combine the first safety design criterion and the second safety design criterion to generate a thermal runaway safety design criterion, wherein the thermal runaway safety design criterion satisfies T max ≤T limit *μ and Q≤Q limit *ζ; The system-level simplified module includes an explosion-proof valve, a heat-conducting material, a liquid cooling plate, and a battery module; The cell module is fixed by clamps at both ends, and includes a heating plate and a plurality of sample cells, wherein each of the sample cells is separated by a heat insulating material, and the heating plate is arranged between the clamp at one end of the cell module and the sample cells; The sample cell is applied to a pre-designed system-level simplified module for thermal analysis to obtain system-level thermal runaway data, including: Heating the heating plate triggers thermal runaway of the first sample battery cell starting from one side of the heating plate, and obtains the side temperature of the first sample battery cell close to the heating plate and the amount of heat absorbed by the first sample battery cell; When the first sample battery cell reaches thermal runaway, obtaining a net heat flux of the second sample battery cell starting from one side of the heating plate; System-level thermal runaway data is generated based on the net heat flux of the second sample battery cell, the side temperature of the first sample battery cell close to the heating plate, and the amount of heat absorbed by the first sample battery cell.

7. A thermal runaway safety design evaluation device, characterized in that: including memory and processor; The memory is used to store programs; The processor is used to execute the program to implement each step of the thermal runaway safety design evaluation method as described in any one of claims 1 to 5.

8. A readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, each step of the thermal runaway safety design evaluation method according to any one of claims 1 to 5 is implemented.

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