Battery thermal diffusion test method and system and storage medium

Abstract

The invention relates to a battery thermal diffusion test method and system, and a storage medium. The method comprises the following steps: obtaining pre-test characteristic information of a battery pack to be tested; the battery pack to be tested comprises a target battery cell and a plurality of adjacent battery cells; after the target cell is controlled to trigger thermal runaway, obtaining first test characteristic information of each corresponding adjacent cell; and when the characteristic information before the test and the first test characteristic information corresponding to any adjacent cell meet the first preset thermal runaway condition, determining that thermal diffusion occurs in the battery pack to be tested, so that the thermal diffusion test of the battery pack to be tested is realized, the whole battery panel does not need to be used as a test sample for testing, the high test cost and the high test difficulty are reduced, and the test efficiency is improved. And the accuracy and the reliability of a thermal diffusion test result are improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and in particular, to a battery thermal diffusion test method, system, and storage medium. Background Art

[0002] After any single cell in a battery pack undergoes thermal runaway, the released heat and high-temperature substances spread to adjacent cells, easily triggering a chain thermal runaway, that is, the phenomenon of battery thermal diffusion occurs. Battery thermal diffusion not only causes damage to the battery pack but also seriously threatens the personal safety of users. Battery thermal diffusion testing is an important means to evaluate the safety performance of batteries. The relevant parameters such as battery temperature and gas production pressure obtained from the test results can visually characterize the battery thermal diffusion characteristics.

[0003] Currently, in existing battery thermal diffusion tests, battery packs are usually used as test samples, with high test costs and great test difficulties. In order to reduce test costs and time, the number of tests on the battery pack is usually reduced, resulting in a decrease in the accuracy and reliability of the thermal diffusion test results. Summary of the Invention

[0004] Based on this, a battery thermal diffusion test method, system, and storage medium are provided.

[0005] In a first aspect, the present application provides a battery thermal diffusion test method, including the following steps:

[0006] Obtain the pre-test characteristic information of the battery pack to be tested; the battery pack to be tested includes a target cell and a plurality of adjacent cells;

[0007] After controlling the target cell to trigger thermal runaway, obtain the first test characteristic information of each corresponding adjacent cell;

[0008] When the pre-test characteristic information and the first test characteristic information of any one of the corresponding adjacent cells satisfy the first preset thermal runaway condition, it is determined that the battery pack to be tested has undergone thermal diffusion.

[0009] In one embodiment, the pre-test characteristic information includes the first pre-test sample state information; the first test characteristic information includes the first test temperature and the first post-test sample state information;

[0010] The step of determining that the battery pack to be tested has undergone thermal diffusion when the pre-test characteristic information and the first test characteristic information of any one of the corresponding adjacent cells satisfy the first preset thermal runaway condition includes:

[0011] When the rising rate of the first test temperature continuously exceeds the first threshold for the first preset time and the comparison result between the first post-test sample state information and the first pre-test sample state information satisfies the first comparison condition, it is determined that the battery pack to be tested has undergone thermal diffusion.

[0012] In one embodiment, the first pre - test sample status information includes the first initial voltage, the initial mass, and the first initial explosion - proof valve image; the first post - test sample status information includes the first test voltage, the test mass, and the first test explosion - proof valve image;

[0013] The judgment step for the comparison result of the first post - test sample status information and the first pre - test sample status information to meet the first comparison condition includes:

[0014] The difference between the first test voltage and the first initial voltage exceeds the first voltage difference, the difference between the test mass and the initial mass exceeds the mass difference, or the characteristic matching difference between the first test explosion - proof valve image and the first initial explosion - proof valve image exceeds the first matching threshold.

[0015] In one embodiment, before the step of obtaining the first test characteristic information of each corresponding adjacent battery cell after the target battery cell is triggered to thermal runaway, it includes:

[0016] Obtain the second test characteristic information of the target battery cell during the charging process or the heating process;

[0017] When the pre - test characteristic information and the second test characteristic information meet the second preset thermal runaway condition, it is determined that the target battery cell has thermal runaway.

[0018] In one embodiment, the target pre - test characteristic information further includes the second pre - test sample status information; the second test characteristic information includes the second test temperature and the second post - test sample status information;

[0019] The step of determining that the target battery cell has thermal runaway when the pre - test characteristic information and the second test characteristic information meet the second preset thermal runaway condition includes:

[0020] When the rising rate of the second test temperature continues to exceed the second threshold for the second preset time and the comparison result of the second post - test sample status information and the second pre - test sample status information meets the second comparison condition, it is determined that the target battery cell has thermal runaway.

[0021] In one embodiment, the battery pack to be tested is arranged in a test device, and the test device has a pressure - relief cavity; the second pre - test sample status information includes the second initial voltage and the initial pressure in the pressure - relief cavity; the second post - test sample status information includes the second test voltage, the test pressure in the pressure - relief cavity, and the test device pressure - relief valve image;

[0022] The judgment step for the comparison result of the second post - test sample status information and the second pre - test sample status information to meet the second comparison condition includes:

[0023] The difference between the second test voltage and the second initial voltage exceeds the second voltage difference, the difference between the test pressure in the pressure relief chamber and the initial pressure in the pressure relief chamber exceeds the pressure threshold, or the feature matching value of the image of the pressure relief valve of the test device exceeds the second matching threshold.

[0024] In one embodiment, the battery thermal diffusion test method further includes the steps of:

[0025] Based on a preset height of the pressure relief chamber, perform thermal diffusion tests on at least two groups of battery packs to be tested;

[0026] When thermal diffusion does not occur in each battery pack to be tested, increase the preset height of the pressure relief chamber based on a first step value, and perform thermal diffusion tests on each battery pack to be tested again according to the increased preset height of the pressure relief chamber until thermal diffusion occurs in any one of the battery packs to be tested;

[0027] When thermal diffusion occurs in any one of the battery packs to be tested, determine the last increased preset height of the pressure relief chamber as the target pressure relief chamber height.

[0028] In one embodiment, after the step of performing thermal diffusion tests on at least two groups of battery packs to be tested based on a preset height of the pressure relief chamber, it includes:

[0029] When thermal diffusion occurs in at least one of the battery packs to be tested, decrease the preset height of the pressure relief chamber based on a second step value, and perform thermal diffusion tests on each battery pack to be tested again according to the decreased preset height of the pressure relief chamber until thermal diffusion does not occur in each battery pack to be tested;

[0030] When thermal diffusion does not occur in each battery pack to be tested, determine the last decreased preset height of the pressure relief chamber as the target pressure relief chamber height.

[0031] In one embodiment, the battery thermal diffusion test method further includes the steps of:

[0032] Based on a first preset trigger quantity, perform thermal diffusion tests on at least two groups of battery packs to be tested;

[0033] When thermal diffusion does not occur in each battery pack to be tested, increase the first preset trigger quantity based on a third step value, and perform thermal diffusion tests on each battery pack to be tested again according to the increased first preset trigger quantity until thermal diffusion occurs in any one of the battery packs to be tested;

[0034] When thermal diffusion occurs in any one of the battery packs to be tested, determine the last increased first preset trigger quantity as the thermal diffusion trigger boundary quantity.

[0035] In one embodiment, after the step of performing thermal diffusion tests on at least two groups of battery packs to be tested based on a first preset trigger quantity, it includes:

[0036] When thermal diffusion occurs in at least one of the battery packs to be tested, reduce a first preset trigger amount based on a fourth step value, and perform a thermal diffusion test on each battery pack to be tested again according to the reduced first preset trigger amount until thermal diffusion does not occur in any of the battery packs to be tested;

[0037] When thermal diffusion does not occur in any of the battery packs to be tested, determine the last reduced first preset trigger amount as the thermal diffusion trigger boundary amount.

[0038] In one embodiment, the battery thermal diffusion test method further includes the steps of:

[0039] Perform a thermal runaway test on at least two target battery cells based on a second preset trigger amount;

[0040] When thermal runaway does not occur in any of the target battery cells, increase the second preset trigger amount based on a fifth step value, and perform a thermal runaway test on each target battery cell again according to the increased second preset trigger amount until thermal runaway occurs in any one of the target battery cells;

[0041] When thermal runaway occurs in any one of the target battery cells, determine the last increased second preset trigger amount as the thermal runaway trigger boundary amount.

[0042] In one embodiment, after the step of performing a thermal runaway test on at least two target battery cells based on a second preset trigger amount, it includes:

[0043] When thermal runaway occurs in at least one of the target battery cells, reduce the second preset trigger amount based on a sixth step value, and perform a thermal runaway test on each target battery cell again according to the reduced second preset trigger amount until thermal runaway does not occur in any of the target battery cells;

[0044] When thermal runaway does not occur in any of the target battery cells, determine the last reduced second preset trigger amount as the thermal runaway trigger boundary amount.

[0045] In one embodiment, after the step of determining that thermal diffusion has occurred in the battery pack to be tested when the pre-test characteristic information and the first test characteristic information of any one adjacent battery cell satisfy the first preset thermal runaway condition, it includes:

[0046] Obtain a thermal diffusion characteristic parameter table according to the pre-test characteristic information and the first test characteristic information.

[0047] In a second aspect, the present application further provides a battery thermal diffusion test system, including a processing device and a test device;

[0048] The test device is used to fix the battery pack to be tested, and the processing device is connected to the test device and the battery pack to be tested;

[0049] The processing device is used to execute the steps of the battery thermal diffusion test method of any one of the above.

[0050] In a third aspect, the present application also provides a computer storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the battery thermal diffusion test method of any one of the above are implemented.

[0051] One of the above technical solutions has the following advantages and beneficial effects:

[0052] In the above battery thermal diffusion test method, by obtaining the pre-test characteristic information of the battery pack to be tested; the battery pack to be tested includes a target battery cell and several adjacent battery cells; after controlling the target battery cell to trigger thermal runaway, obtaining the first test characteristic information of each corresponding adjacent battery cell; when the pre-test characteristic information and the first test characteristic information of any one of the corresponding adjacent battery cells meet the first preset thermal runaway condition, it is determined that the battery pack to be tested has thermal diffusion, and the thermal diffusion test of the battery pack to be tested is realized. The present application does not need to use the entire battery panel as a test sample for testing. Only a target battery cell and several adjacent battery cells are used, and the pre-test characteristic information of the target battery cell and several adjacent battery cells is obtained. By triggering thermal runaway of the target battery cell, the first test characteristic information of the adjacent battery cells is obtained, and then according to the pre-test characteristic information and the first test characteristic information, it is judged whether the battery pack to be tested has thermal diffusion, improving the accuracy and reliability of the thermal diffusion test result, and reducing the high test cost and large test difficulty. Description of the Drawings

[0053] Figure 1 It is a schematic diagram of the application environment of the battery thermal diffusion test method in the embodiment of the present application;

[0054] Figure 2 It is a first flow chart of the battery thermal diffusion test method in the embodiment of the present application;

[0055] Figure 3 It is a flow chart of the determination step of the thermal runaway of the target battery cell in the embodiment of the present application;

[0056] Figure 4 It is a flow chart of the determination step of the height boundary of the pressure relief cavity in the embodiment of the present application;

[0057] Figure 5 It is a flow chart of the determination step of the thermal diffusion trigger boundary quantity in the embodiment of the present application;

[0058] Figure 6 It is a flow chart of the determination step of the thermal runaway trigger boundary quantity in the embodiment of the present application;

[0059] Figure 7 It is a schematic diagram of the structure of the battery thermal diffusion test system in the embodiment of the present application. Detailed Implementation Manner

[0060] To enable those skilled in the art to better understand the solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0061] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned accompanying drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that such data used in appropriate cases can be interchanged so as to implement the embodiments of this application described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0062] In addition, the meaning of the term "plurality" should be two or more.

[0063] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will detail this application with reference to the accompanying drawings and in conjunction with the embodiments.

[0064] The battery thermal diffusion test method provided by this application can be applied to an application environment as shown in Figure 1 wherein, the processing device may include a processor 102 and a memory 104. The memory 104 can be used to store data such as pre-test characteristic information and first test characteristic information. The processor 102 can be used to obtain the pre-test characteristic information of the battery pack to be tested; the battery pack to be tested includes a target battery cell and several adjacent battery cells; after controlling the target battery cell to trigger thermal runaway, obtain the first test characteristic information of each corresponding adjacent battery cell; when the pre-test characteristic information and the first test characteristic information of any one of the corresponding adjacent battery cells meet the first preset thermal runaway condition, determine that the battery pack to be tested has thermal diffusion. The processing device may further include a display 106, and the display 106 can display data such as pre-test characteristic information and first test characteristic information through a graphical interface. Exemplarily, the processing device is connected to the battery pack to be tested through a battery thermal diffusion test device, and the battery thermal diffusion test device is used to fix the battery pack to be tested.

[0065] In one embodiment, as shown in Figure 2As shown, a battery thermal diffusion test method is also provided, which is applied to the battery thermal diffusion test device as described in any of the above items. The battery thermal diffusion test method includes the following steps:

[0066] Step S210: Obtain the pre-test characteristic information of the battery pack to be tested; the battery pack to be tested includes a target battery cell and several adjacent battery cells.

[0067] Among them, the battery pack to be tested may include at least 2 single battery cells, and each single battery cell can be divided into a target battery cell and at least 1 adjacent battery cell. The single battery cell can be a cylindrical battery cell. For example, the single battery cell can be a 4695-type cylindrical battery. In another example, the single battery cell can also be other types of cylindrical batteries. For example, the single battery cell can be cylindrical battery cells of different heights and different material systems in the 46XX series. Exemplarily, the battery pack to be tested includes 1 target battery cell and 6 adjacent battery cells. It should be noted that the target battery cell and each adjacent battery cell in the same battery pack to be tested are good products produced in the same batch, the target battery cell and each adjacent battery cell have the same model, and the target battery cell and each adjacent battery cell have good consistency (the relative range of capacity < 1%, and the relative range of ACR (alternating current internal resistance) value < 1%); each adjacent battery cell is arranged around the target battery cell so that each adjacent battery cell is adjacent to the target battery cell respectively.

[0068] For example, before testing the battery pack to be tested, charge the target battery cell and each adjacent battery cell to full charge (100% SOC), and record the pre-test sample state of the target battery cell and each adjacent battery cell in the battery pack to be tested, so as to obtain the pre-test characteristic information of the battery pack to be tested. It should be noted that the pre-test characteristic information includes the characteristic information of the target battery cell and the corresponding adjacent battery cell. The pre-test characteristic information may include quality information, voltage information, and battery cell explosion-proof valve image information detected before the test, etc.

[0069] Step S220: After controlling the target battery cell to trigger thermal runaway, obtain the first test characteristic information of each corresponding adjacent battery cell.

[0070] Among them, the first test characteristic information refers to the characteristic information obtained by detecting the corresponding adjacent battery cell after the target battery cell undergoes thermal runaway. For example, the first test characteristic information may include temperature information, voltage information, and battery cell explosion-proof valve image information obtained during the test, etc.

[0071] Fix the battery pack to be tested in the battery thermal diffusion test device, trigger thermal runaway of the target battery cell, and obtain the first test characteristic information of each corresponding adjacent battery cell when the target battery cell triggers thermal runaway.

[0072] Step S230: When the pre-test characteristic information and the first test characteristic information of any one corresponding adjacent battery cell meet the first preset thermal runaway condition, determine that the battery pack to be tested has undergone thermal diffusion.

[0073] Among them, the first preset thermal runaway condition can be obtained through system presetting, and the first preset thermal runaway condition is used to determine whether the adjacent battery cell has a thermal runaway.

[0074] For example, based on the first preset thermal runaway condition, the characteristics information before testing and each first test characteristics information are processed. And according to the processing results, when the characteristics information before testing and the first test characteristics information of any corresponding adjacent battery cell satisfy the first preset thermal runaway condition, it is determined that the corresponding adjacent battery cell has a thermal runaway, and then it is determined that the battery pack to be tested has a thermal diffusion, so as to realize the thermal diffusion test of the battery pack to be tested.

[0075] In the above embodiment, the characteristics information before testing of the battery pack to be tested is obtained; the battery pack to be tested includes a target battery cell and several adjacent battery cells; after controlling the target battery cell to trigger a thermal runaway, the first test characteristics information of each corresponding adjacent battery cell is obtained; when the characteristics information before testing and the first test characteristics information of any corresponding adjacent battery cell satisfy the first preset thermal runaway condition, it is determined that the battery pack to be tested has a thermal diffusion, so as to realize the thermal diffusion test of the battery pack to be tested. This application does not need to use the entire battery panel as a test sample for testing. Only the target battery cell and several adjacent battery cells are used, and the characteristics information before testing of the target battery cell and several adjacent battery cells is obtained. By triggering a thermal runaway of the target battery cell, the first test characteristics information of the adjacent battery cells is obtained, and then according to the characteristics information before testing and the first test characteristics information, it is judged whether the battery pack to be tested has a thermal diffusion, which improves the accuracy and reliability of the thermal diffusion test results and reduces the high test cost and large test difficulty.

[0076] In one embodiment, the characteristics information before testing includes the first sample state information before testing; the first test characteristics information includes the first test temperature and the first sample state information after testing. The steps of determining that the battery pack to be tested has a thermal diffusion when the characteristics information before testing and the first test characteristics information of any corresponding adjacent battery cell satisfy the first preset thermal runaway condition include:

[0077] When the rising rate of the first test temperature exceeds the first threshold for a first preset time and the comparison result between the first sample state information after testing and the first sample state information before testing satisfies the first comparison condition, it is determined that the battery pack to be tested has a thermal diffusion.

[0078] Among them, the first pre-test sample status information refers to the pre-test sample status information of the corresponding adjacent battery cell. For example, the first pre-test sample status information may include the quality information, voltage information, and battery cell explosion-proof valve image information of the adjacent battery cell obtained by pre-test detection, etc. The first post-test sample status information refers to the sample status information obtained by detecting the corresponding adjacent battery cell after thermal runaway occurs in the target battery cell. For example, the first post-test sample status information may include the voltage information, quality information, and battery cell explosion-proof valve image information obtained by testing, etc. The first test temperature may be the temperature data at different detection time points obtained by detecting the temperature of the corresponding adjacent battery cell based on a preset detection period after thermal runaway occurs in the target battery cell.

[0079] Exemplarily, when performing a thermal diffusion test on a battery pack to be tested, the battery pack to be tested is fixed in a battery thermal diffusion test device, and the target battery cell is triggered to undergo thermal runaway based on a preset trigger condition. After detecting that the target battery cell has undergone thermal runaway, the temperature of each adjacent battery cell and the sample status are detected, and then the first test temperature and the first post-test sample status information of the corresponding adjacent battery cell are obtained. According to the first test temperature of the adjacent battery cell, the rising rate of the first test temperature is obtained, and the rising rate of the first test temperature is compared with a first threshold (such as 1 °C / s). When the rising rate of the first test temperature continuously exceeds the first threshold for a first preset time (such as more than 3 s), the first post-test sample status information of the corresponding adjacent battery cell is compared with the first pre-test sample status information, and when the comparison result meets the first comparison condition, it is determined that the corresponding adjacent battery cell has undergone thermal runaway, and then it is determined that the battery pack to be tested has undergone thermal diffusion, realizing an accurate judgment of the thermal diffusion test result of the battery pack to be tested and improving the reliability of the thermal diffusion test result.

[0080] In one embodiment, the first pre-test sample status information includes a first initial voltage, an initial mass, and a first initial explosion-proof valve image; the first post-test sample status information includes a first test voltage, a test mass, and a first test explosion-proof valve image. The judgment steps for the comparison result of the first post-test sample status information and the first pre-test sample status information to meet the first comparison condition include:

[0081] The difference between the first test voltage and the first initial voltage exceeds a first voltage difference, the difference between the test mass and the initial mass exceeds a mass difference, or the characteristic matching difference between the first test explosion-proof valve image and the first initial explosion-proof valve image exceeds a first matching threshold.

[0082] Among them, by detecting the voltage of the adjacent battery cells before each test, the first initial voltage of the corresponding adjacent battery cells is obtained; by weighing the adjacent battery cells before each test, the initial mass of the corresponding adjacent battery cells is obtained; by acquiring the explosion-proof valve images of the adjacent battery cells before each test, the first initial explosion-proof valve images of the corresponding adjacent battery cells are obtained. It should be noted that the explosion-proof valve in the first initial explosion-proof valve image is in the unopened state. The first test voltage refers to the voltage value obtained by detecting the voltage of the corresponding adjacent battery cells based on a preset period after the target battery cell undergoes thermal runaway. The test mass refers to the mass value obtained by weighing the corresponding adjacent battery cells after the target battery cell undergoes thermal runaway. The first test explosion-proof valve image is obtained by acquiring the image of the explosion-proof valve of the corresponding adjacent battery cell after the target battery cell undergoes thermal runaway.

[0083] For example, during the thermal diffusion test of the battery pack to be tested, when the rising rate of the first test temperature lasts for the first preset time and exceeds the first threshold, the difference between the first test voltage and the first initial voltage is compared with the first voltage difference. When the difference between the first test voltage and the first initial voltage exceeds the first voltage difference (such as 75% of the initial voltage value), it is determined that the corresponding adjacent battery cell has undergone thermal runaway, and then it is determined that the battery pack to be tested has undergone thermal diffusion. Another example is that during the thermal diffusion test of the battery pack to be tested, when the rising rate of the first test temperature lasts for the first preset time and exceeds the first threshold, the difference between the test mass and the initial mass is compared with the mass difference. When the difference between the test mass and the initial mass exceeds the mass difference, it is determined that the corresponding adjacent battery cell has undergone thermal runaway, and then it is determined that the battery pack to be tested has undergone thermal diffusion. Another example is that during the thermal diffusion test of the battery pack to be tested, when the rising rate of the first test temperature lasts for the first preset time and exceeds the first threshold, the feature matching difference between the first test explosion-proof valve image and the first initial explosion-proof valve image is compared with the first matching threshold. When the feature matching difference between the first test explosion-proof valve image and the first initial explosion-proof valve image exceeds the first matching threshold, it is determined that the explosion-proof valve of the corresponding adjacent battery cell is opened, that is, the adjacent battery cell has undergone thermal runaway, and then it is determined that the battery pack to be tested has undergone thermal diffusion, realizing an accurate judgment of the thermal diffusion test result of the battery pack to be tested and improving the reliability of the thermal diffusion test result.

[0084] In another example, during the thermal diffusion test of the battery pack to be tested, when the rising rate of the first test temperature lasts for the first preset time and exceeds the first threshold, among the conditions that the difference between the first test voltage and the first initial voltage exceeds the first voltage difference, the difference between the test mass and the initial mass exceeds the mass difference, and the feature matching difference between the first test explosion-proof valve image and the first initial explosion-proof valve image exceeds the first matching threshold, when at least 2 comparison conditions are met, it is determined that the corresponding adjacent battery cell has undergone thermal runaway, and then it is determined that the battery pack to be tested has undergone thermal diffusion, thereby further improving the accuracy and reliability of the thermal diffusion test result.

[0085] In one embodiment, such asFigure 3 As shown, before the step of obtaining the first test characteristic information of each corresponding adjacent battery cell after triggering thermal runaway of the target battery cell, the following steps are included:

[0086] Step S310: Obtain the second test characteristic information of the target battery cell during the charging process or the heating process.

[0087] Among them, the second test characteristic information may include temperature information, voltage information, pressure information in the pressure relief chamber, etc. during the test process of the target battery cell.

[0088] For example, when the triggering method of thermal diffusion is overcharge triggering, temperature monitoring wires and voltage monitoring wires can be arranged for the target battery cell. For example, 1 temperature monitoring wire is set at the positive electrode surface and the side surface of the target battery cell respectively, and they are connected and fixed by high-temperature tape. The probes of the temperature monitoring wires are wrapped with high-temperature tape to achieve insulation; 1 voltage monitoring wire is set at the positive electrode surface and the negative electrode surface of the target battery cell respectively, and they are connected and fixed by welding. The target battery cell is connected to an external power supply device (such as a charge and discharge cabinet). After the test is started, the external power supply device is started, and the external power supply device charges the target battery cell with a constant current (for example, the current selection range is 1C to 5C). After the target battery cell triggers thermal runaway, the external power supply device is turned off, so that the target battery cell stops charging, and it is left standing and observed for 24 hours. The test data is recorded throughout the process, and thus the second test characteristic information is obtained.

[0089] Another example, when the triggering method of thermal diffusion is heating triggering, a heating sheet, temperature monitoring wires and voltage monitoring wires can be arranged for the target battery cell. Among them, the arrangement methods of the temperature monitoring wires and voltage monitoring wires are as described in the above overcharge triggering, and will not be elaborated here. The heating sheet is an electric heating plate that generates heat on the plate surface after being energized without being charged and without open fire. Its shape is arc-shaped. The heating sheet is attached to the side surface of the target battery cell, connected and fixed by high-temperature tape, and then covered with a heat insulation sheet (such as mica sticker) to ensure that the heat released by the heating sheet is mainly transferred to the target battery cell. The heating sheet is connected to an external power supply device (such as a DC power supply) through a wire. After the test is started, the external power supply device is started, and the heating power of the heating sheet is controlled to be constant (for example, the power selection range is 100W to 300W) to heat the target battery cell. After the target battery cell triggers thermal runaway, the external power supply device is turned off, and the heating of the target battery cell is stopped. It is left standing and observed for 24 hours. The test data is recorded throughout the process, and thus the second test characteristic information is obtained.

[0090] It should be noted that after the test is completed, the battery thermal diffusion test device can also be disassembled, the battery pack to be tested can be taken out, and the state of the sample after the test can be recorded, and thus the image of the explosion-proof valve after the test can be obtained.

[0091] Step S320: When the pre-test characteristic information and the second test characteristic information meet the second preset thermal runaway condition, determine that the target battery cell has thermal runaway.

[0092] Based on the second preset thermal runaway condition, process the pre-test characteristic information and the second test characteristic information. According to the processing results, when the pre-test characteristic information and the second test characteristic information meet the second preset thermal runaway condition, determine that the target battery cell has a thermal runaway, and then determine that thermal diffusion occurs in the battery pack under test, so as to realize the thermal diffusion test of the battery pack under test. Furthermore, after the target battery cell triggers a thermal runaway, obtain the first test characteristic information of the adjacent battery cell, and judge whether thermal diffusion occurs in the battery pack under test based on the pre-test characteristic information and the first test characteristic information, which is convenient for conducting a large number of thermal diffusion tests on the battery pack under test, improves the accuracy and reliability of the thermal diffusion test results, and reduces the high test cost and large test difficulty.

[0093] In one embodiment, the pre-test characteristic information of the target also includes the second pre-test sample state information; the second test characteristic information includes the second test temperature and the second post-test sample state information. The steps for determining that the target battery cell has a thermal runaway when the pre-test characteristic information and the second test characteristic information meet the second preset thermal runaway condition include:

[0094] When the rising rate of the second test temperature continues to exceed the second threshold for the second preset time and the comparison result between the second post-test sample state information and the second pre-test sample state information meets the second comparison condition, determine that the target battery cell has a thermal runaway.

[0095] Among them, the second pre-test sample state information refers to the pre-test sample state information of the target battery cell. For example, the second pre-test sample state information may include voltage information and cell explosion-proof valve image information of the target battery cell detected before the test. The second post-test sample state information refers to the sample state information obtained by detecting the target battery cell during the thermal runaway triggering process of the target battery cell. For example, the second post-test sample state information may include pressure information in the pressure relief chamber, voltage information, and cell explosion-proof valve image information obtained by testing. The second test temperature can be temperature data at different detection time points obtained by detecting the temperature of the target battery cell based on a preset detection period during the thermal runaway triggering process of the target battery cell.

[0096] Exemplarily, when performing a thermal diffusion test on a battery pack under test, the battery pack under test is fixed inside a battery thermal diffusion test device, and a thermal runaway of a target battery cell is triggered based on a preset triggering condition (such as overcharge triggering or heating triggering). During the triggering process of the thermal runaway of the target battery cell, temperature detection and sample state detection are performed on the target battery cell, and then a second test temperature and second post-test sample state information of the target battery cell are obtained. According to the second test temperature of the target battery cell, the rising rate of the second test temperature is obtained, and the rising rate of the second test temperature is compared with a second threshold value (such as 1 °C / s). When the rising rate of the second test temperature continuously exceeds the second threshold value for a second preset time (such as more than 3 s), the second post-test sample state information of the target battery cell is compared with the second pre-test sample state information, and when the comparison result meets the second comparison condition, it is determined that the target battery cell has experienced thermal runaway, achieving an accurate and reliable determination of the thermal runaway of the target battery cell.

[0097] In one embodiment, the battery pack under test is arranged in the test device, and the test device has a pressure relief chamber; the second pre-test sample state information includes a second initial voltage and an initial pressure in the pressure relief chamber; the second post-test sample state information includes a second test voltage, a measured pressure in the pressure relief chamber, and an image of the pressure relief valve of the test device. The determination steps for the comparison result between the second post-test sample state information and the second pre-test sample state information to meet the second comparison condition include:

[0098] The difference between the second test voltage and the second initial voltage exceeds a second voltage difference, the difference between the measured pressure in the pressure relief chamber and the initial pressure in the pressure relief chamber exceeds a pressure threshold value, or the feature matching value of the image of the pressure relief valve of the test device exceeds a second matching threshold value.

[0099] Among them, the test device refers to a battery thermal diffusion test device, and the test device is provided with a pressure relief chamber. When the battery pack under test is installed in the test device, the explosion-proof valve of the battery cell of the battery pack under test is arranged corresponding to the pressure relief chamber. By performing voltage detection on the target battery cell before each test, the second initial voltage of the target battery cell is obtained; by performing pressure detection on the pressure relief chamber of the test device before each test, the initial pressure in the pressure relief chamber of the target battery cell is obtained. The second test voltage refers to the voltage value obtained by detecting the voltage of the corresponding target battery cell based on a preset period during the triggering process of the thermal runaway of the target battery cell. The measured pressure in the pressure relief chamber refers to the pressure value obtained by detecting the pressure in the pressure relief chamber of the test device during the triggering process of the thermal runaway of the target battery cell. The image of the pressure relief valve of the test device is obtained by acquiring an image of the pressure relief valve of the test device during the triggering process of the thermal runaway of the target battery cell. It should be noted that when the pressure relief valve of the test device is opened, the high-temperature and high-pressure gas in the pressure relief chamber sprays out from the pressure relief valve.

[0100] For example, during the process of triggering thermal runaway of the target battery cell, when the rising rate of the second test temperature lasts for a second preset time and exceeds a second threshold, the difference between the second test voltage and the second initial voltage is compared with a second voltage difference. When the difference between the second test voltage and the second initial voltage exceeds the second voltage difference (such as 75% of the initial voltage value), it is determined that the target battery cell has experienced thermal runaway. Another example is that during the process of triggering thermal runaway of the target battery cell, when the rising rate of the second test temperature lasts for a second preset time and exceeds a second threshold, the difference between the pressure in the test pressure relief chamber and the initial pressure in the pressure relief chamber is compared with a pressure threshold. When the difference between the pressure in the test pressure relief chamber and the initial pressure in the pressure relief chamber exceeds the pressure threshold (such as 106 kPa), it is determined that the target battery cell has experienced thermal runaway. Still another example is that during the process of triggering thermal runaway of the target battery cell, when the rising rate of the second test temperature lasts for a second preset time and exceeds a second threshold, the feature matching value of the image of the pressure relief valve of the test device is compared with a second matching threshold. When the feature matching value of the image of the pressure relief valve of the test device exceeds the second matching threshold, it is determined that there is smoke at the pressure relief valve of the test device, that is, the target battery cell has experienced thermal runaway, achieving an accurate judgment of the thermal runaway test result of the target battery cell and improving the reliability of the thermal runaway test of the target battery cell.

[0101] In another example, during the process of triggering thermal runaway of the target battery cell, when the rising rate of the second test temperature lasts for a second preset time and exceeds a second threshold, among the conditions that the difference between the second test voltage and the second initial voltage exceeds the second voltage difference, the difference between the pressure in the test pressure relief chamber and the initial pressure in the pressure relief chamber exceeds the pressure threshold, and the feature matching value of the image of the pressure relief valve of the test device exceeds the second matching threshold, when at least two comparison conditions are met, it is determined that the target battery cell has experienced thermal runaway, thereby further improving the accuracy and reliability of the thermal runaway test of the target battery cell.

[0102] In one embodiment, as Figure 4 shown, the battery thermal diffusion test method further includes the steps of:

[0103] Step S410: Based on a preset pressure relief chamber height, perform thermal diffusion tests on at least two groups of battery packs to be tested.

[0104] Among them, the preset pressure relief chamber height refers to the initially set height of the pressure relief chamber. For example, the preset pressure relief chamber height is 5 mm.

[0105] Exemplarily, three groups of battery packs to be tested can be set for parallel testing, and the three groups of battery packs to be tested are good products produced in the same batch. The height of the pressure relief chamber of the battery thermal diffusion test device is set to 5 mm, and thermal diffusion tests are performed on the three groups of battery packs to be tested based on the battery thermal diffusion test method of the above embodiment, and then according to the test results, it is determined whether thermal diffusion occurs in the three groups of battery packs to be tested.

[0106] Step S420: When thermal diffusion does not occur in each battery pack under test, increase the preset pressure relief chamber height based on the first step value, and perform thermal diffusion tests on each battery pack under test again according to the increased preset pressure relief chamber height until thermal diffusion occurs in any one of the battery packs under test.

[0107] For example, the first step value can be set to 1 mm or 1.5 mm, etc. When performing the thermal diffusion test on each battery pack under test for the first time, if thermal diffusion does not occur in each battery pack under test, increase the height of the pressure relief chamber of the battery thermal diffusion test device by the first step value, and return to step S410 to perform the thermal diffusion test on each battery pack under test again according to the increased preset pressure relief chamber height until thermal diffusion occurs in any one of the battery packs under test for the Nth time, and then end the cyclic thermal diffusion test. It should be noted that N is a positive integer greater than or equal to 2.

[0108] Step S430: When thermal diffusion occurs in any one of the battery packs under test, determine the last increased preset pressure relief chamber height as the target pressure relief chamber height.

[0109] When thermal diffusion occurs in any one of the battery packs under test, further determine that the optimal height (i.e., the target pressure relief chamber height) of the pressure relief chamber in the test device is the last increased preset pressure relief chamber height, that is, the optimal height of the pressure relief chamber in the test device = preset pressure relief chamber height + (N - 1) * 1 mm, so as to realize the verification test of the pressure relief chamber height design of the battery pack box body corresponding to the battery pack under test, facilitate the selection test of the explosion-proof valve of the battery pack box body, and can more comprehensively, objectively and conveniently carry out the research on the battery thermal diffusion characteristics, which is beneficial to the design and improvement of the battery safety performance and also provides a parameter basis for the design of the protection device in the battery pack.

[0110] In one embodiment, as Figure 4 shown, after the step of performing thermal diffusion tests on at least two battery packs under test based on the preset pressure relief chamber height, it includes:

[0111] Step S440: When thermal diffusion occurs in at least one of the battery packs under test, decrease the preset pressure relief chamber height based on the second step value, and perform thermal diffusion tests on each battery pack under test again according to the decreased preset pressure relief chamber height until thermal diffusion does not occur in each battery pack under test.

[0112] For example, the second step value can be set to 1 mm, 1.5 mm, etc. When performing the thermal diffusion test on each battery pack to be tested for the first time, if thermal diffusion occurs in at least one of the battery packs to be tested, the height of the pressure relief chamber of the battery thermal diffusion test device is reduced by the second step value, and according to the reduced preset pressure relief chamber height, return to step S410 to perform the thermal diffusion test on each battery pack to be tested again until thermal diffusion does not occur in each battery pack to be tested for the Nth time, and then end the cyclic thermal diffusion test. It should be noted that N is a positive integer greater than or equal to 2.

[0113] Step S450: When thermal diffusion does not occur in each battery pack to be tested, determine the last reduced preset pressure relief chamber height as the target pressure relief chamber height.

[0114] When thermal diffusion does not occur in each battery pack to be tested, further determine the optimal height (i.e., the target pressure relief chamber height) of the pressure relief chamber in the test device as the last reduced preset pressure relief chamber height, that is, the optimal height of the pressure relief chamber in the test device = preset pressure relief chamber height - N * 1 mm, to implement the verification test for the design of the pressure relief chamber height of the battery pack box corresponding to the battery pack to be tested, and be able to accurately obtain the optimal height design of the pressure relief chamber of the battery pack box corresponding to the battery pack to be tested, which is beneficial for the design and improvement of the battery safety performance, and also provides a parameter basis for the design of the protection device in the battery pack.

[0115] In one embodiment, as Figure 5 shown, the battery thermal diffusion test method further includes the steps:

[0116] Step S510: Based on the first preset trigger amount, perform the thermal diffusion test on at least two battery packs to be tested.

[0117] Among them, the first preset trigger amount refers to the initially set target cell thermal runaway trigger amount. For example, when the target cell thermal runaway trigger is overcharge trigger, the first preset trigger amount is the preset charging current, such as the preset charging current is set to 1C. Another example is that when the target cell thermal runaway trigger is heating trigger, the first preset trigger amount is the preset heating power, such as the preset heating power is set to 100W.

[0118] Exemplarily, 3 battery packs to be tested can be set for parallel testing, and the 3 battery packs to be tested are good products produced in the same batch. Using the overcharge trigger for the target cell thermal runaway trigger, setting the first preset trigger amount to 1C, perform the thermal diffusion test on the 3 battery packs to be tested according to the battery thermal diffusion test method of the above embodiment, and then judge whether thermal diffusion occurs in the 3 battery packs to be tested according to the test results.

[0119] In another example, a heating-triggered thermal runaway of the target battery cell is adopted, and the first preset trigger amount is set to 100 W. The thermal diffusion tests are performed on three groups of batteries to be tested based on the battery thermal diffusion test method of the above embodiment, and then, according to the test results, it is determined whether thermal diffusion occurs in the three groups of batteries to be tested.

[0120] Step S520: When thermal diffusion does not occur in each battery group to be tested, increase the first preset trigger amount based on the third step value, and perform the thermal diffusion test on each battery group to be tested again according to the increased first preset trigger amount until thermal diffusion occurs in any one of the battery groups to be tested.

[0121] For example, for the overcharge-triggered thermal runaway of the target battery cell, the third step value can be set to 10%. When the thermal diffusion test is first performed on each battery group to be tested, if thermal diffusion does not occur in each battery group to be tested, increase the first preset trigger amount by 10%, and return to step S510 to perform the thermal diffusion test on each battery group to be tested again according to the increased first preset trigger amount until thermal diffusion occurs in any one of the battery groups to be tested for the Nth time, and then end the cyclic thermal diffusion test. It should be noted that N is a positive integer greater than or equal to 2.

[0122] Another example is that for the heating-triggered thermal runaway of the target battery cell, the third step value can be set to 20 W. When the thermal diffusion test is first performed on each battery group to be tested, if thermal diffusion does not occur in each battery group to be tested, increase the first preset trigger amount by 20 W, and return to step S510 to perform the thermal diffusion test on each battery group to be tested again according to the increased first preset trigger amount until thermal diffusion occurs in any one of the battery groups to be tested for the Nth time, and then end the cyclic thermal diffusion test. It should be noted that N is a positive integer greater than or equal to 2.

[0123] Step S530: When thermal diffusion occurs in any one of the battery groups to be tested, determine the last increased first preset trigger amount as the thermal diffusion trigger boundary amount.

[0124] For example, for the thermal runaway triggering of the target battery cell triggered by overcharging, when thermal diffusion occurs in any one of the battery packs to be tested, the thermal diffusion triggering boundary quantity (i.e., the optimal thermal diffusion overcharging triggering quantity) is the first preset triggering quantity after the last increase, that is, the optimal thermal diffusion overcharging triggering quantity = preset charging current * (1 + (N - 1) * 10%). Another example is that for the thermal runaway triggering of the target battery cell triggered by heating, when thermal diffusion occurs in any one of the battery packs to be tested, the thermal diffusion triggering boundary quantity (i.e., the optimal thermal diffusion heating triggering quantity) is the first preset triggering quantity after the last increase, that is, the optimal thermal diffusion heating triggering quantity = preset heating power + (N - 1) * 20W. This enables accurate testing of the triggering boundary of battery thermal diffusion, and can more comprehensively, objectively, and conveniently carry out research on battery thermal diffusion characteristics.

[0125] In one embodiment, as Figure 5 shown, after the step of performing thermal diffusion tests on at least two battery packs to be tested based on the first preset triggering quantity, it includes:

[0126] Step S540: When thermal diffusion occurs in at least one of the battery packs to be tested, reduce the first preset triggering quantity based on the fourth step value, and based on the reduced first preset triggering quantity, perform thermal diffusion tests on each battery pack to be tested again until thermal diffusion does not occur in any of the battery packs to be tested.

[0127] For example, for the thermal runaway triggering of the target battery cell triggered by overcharging, the fourth step value can be set to 10%. When first performing thermal diffusion tests on each battery pack to be tested, if thermal diffusion occurs in at least one of the battery packs to be tested, reduce the first preset triggering quantity by 10%, and based on the reduced first preset triggering quantity, return to step S510 to perform thermal diffusion tests on each battery pack to be tested again until thermal diffusion does not occur in any of the battery packs to be tested for the Nth time, and then end the cyclic thermal diffusion test. It should be noted that N is a positive integer greater than or equal to 2.

[0128] Another example is that for the thermal runaway triggering of the target battery cell triggered by heating, the fourth step value can be set to 20W. When first performing thermal diffusion tests on each battery pack to be tested, if thermal diffusion occurs in at least one of the battery packs to be tested, reduce the first preset triggering quantity by 20W, and based on the reduced first preset triggering quantity, return to step S510 to perform thermal diffusion tests on each battery pack to be tested again until thermal diffusion does not occur in any of the battery packs to be tested for the Nth time, and then end the cyclic thermal diffusion test. It should be noted that N is a positive integer greater than or equal to 2.

[0129] Step S550: When thermal diffusion does not occur in any of the battery packs to be tested, determine the last reduced first preset triggering quantity as the thermal diffusion triggering boundary quantity.

[0130] For example, for the thermal runaway trigger of the target battery cell triggered by overcharging, when thermal diffusion has not occurred in each battery pack under test, the thermal diffusion trigger boundary quantity (i.e., the optimal thermal diffusion overcharging trigger quantity) is the first preset trigger quantity after the last reduction, that is, the optimal thermal diffusion overcharging trigger quantity = preset charging current * (1 - N * 10%). Another example is that for the thermal runaway trigger of the target battery cell triggered by heating, when thermal diffusion has not occurred in each battery pack under test, the thermal diffusion trigger boundary quantity (i.e., the optimal thermal diffusion heating trigger quantity) is the first preset trigger quantity after the last reduction, that is, the optimal thermal diffusion heating trigger quantity = preset heating power - N * 20W. This can achieve accurate testing of the trigger boundary of battery thermal diffusion, and can more comprehensively, objectively and conveniently carry out research on battery thermal diffusion characteristics, further improving the accuracy and reliability of battery thermal diffusion testing.

[0131] In one embodiment, as Figure 6 shown, the battery thermal diffusion testing method further includes the steps:

[0132] Step S610: Based on a second preset trigger quantity, perform thermal runaway testing on at least two target battery cells.

[0133] Among them, the second preset trigger quantity refers to the initially set thermal runaway trigger quantity of the target battery cell. For example, when the thermal runaway trigger of the target battery cell is triggered by overcharging, the second preset trigger quantity is the preset charging current. For example, the preset charging current is set to 1C. Another example is that when the thermal runaway trigger of the target battery cell is triggered by heating, the second preset trigger quantity is the preset heating power. For example, the preset heating power is set to 100W.

[0134] Exemplarily, 3 groups of target battery cells can be set for parallel testing, and the 3 groups of target battery cells are good products produced in the same batch. Using the thermal runaway trigger of the target battery cell triggered by overcharging, set the second preset trigger quantity to 1C, and perform thermal runaway testing on the 3 groups of target battery cells based on the battery thermal runaway testing method of the above embodiment, and then judge whether the 3 groups of target battery cells have thermal runaway according to the test results. Another example is that using the thermal runaway trigger of the target battery cell triggered by heating, set the second preset trigger quantity to 100W, and perform thermal runaway testing on the 3 groups of target battery cells based on the battery thermal runaway testing method of the above embodiment, and then judge whether the 3 groups of target battery cells have thermal runaway according to the test results.

[0135] Step S620: When thermal runaway has not occurred in each target battery cell, increase the second preset trigger quantity based on a fifth step value, and perform thermal runaway testing on each target battery cell again according to the increased second preset trigger quantity until thermal runaway occurs in any one of the target battery cells.

[0136] For example, for the thermal runaway triggering of the target battery cells triggered by overcharging, the fifth step increment can be set to 10%. When no thermal runaway occurs in any of the target battery cells for the first time, if no thermal runaway occurs in any of the target battery cells, the second preset trigger amount is increased by 10%, and based on the increased second preset trigger amount, return to step S610 to perform the thermal runaway test on each of the target battery cells again until thermal runaway occurs in any one group of the target battery cells for the Nth time, and then end the cyclic thermal runaway test. It should be noted that N is a positive integer greater than or equal to 2.

[0137] For another example, for the thermal runaway triggering of the target battery cells triggered by heating, the fifth step increment can be set to 20 W. When no thermal runaway occurs in any of the target battery cells for the first time, if no thermal runaway occurs in any of the target battery cells, the second preset trigger amount is increased by 20 W, and based on the increased second preset trigger amount, return to step S610 to perform the thermal runaway test on each of the target battery cells again until thermal runaway occurs in any one group of the target battery cells for the Nth time, and then end the cyclic thermal runaway test. It should be noted that N is a positive integer greater than or equal to 2.

[0138] Step S630: When thermal runaway occurs in any one of the target battery cells, determine the last increased second preset trigger amount as the thermal runaway trigger boundary amount.

[0139] For example, for the thermal runaway triggering of the target battery cells triggered by overcharging, when thermal runaway occurs in any one of the target battery cells, the thermal runaway trigger boundary amount (i.e., the optimal thermal runaway overcharge trigger amount) is the last increased second preset trigger amount, that is, the optimal thermal runaway overcharge trigger amount = preset charging current * (1 + (N - 1) * 10%). For another example, for the thermal runaway triggering of the target battery cells triggered by heating, when thermal runaway occurs in any one of the target battery cells, the thermal runaway trigger boundary amount (i.e., the optimal thermal runaway heating trigger amount) is the last increased second preset trigger amount, that is, the optimal thermal runaway heating trigger amount = preset heating power + (N - 1) * 20 W, which realizes accurate testing of the trigger boundary of battery thermal runaway and can more comprehensively, objectively and conveniently carry out research on battery thermal runaway characteristics.

[0140] In one embodiment, after the step of performing the thermal runaway test on at least two target battery cells based on the second preset trigger amount, it includes:

[0141] Step S640: When thermal runaway occurs in at least one of the target battery cells, reduce the second preset trigger amount based on the sixth step increment, and based on the reduced second preset trigger amount, perform the thermal runaway test on each of the target battery cells again until no thermal runaway occurs in any of the target battery cells.

[0142] For example, for the thermal runaway triggering of the target battery cells triggered by overcharging, the sixth step increment can be set to 10%. When performing the thermal runaway test on each target battery cell for the first time, if at least one of the target battery cells experiences thermal runaway, the second preset trigger amount is reduced by 10%, and based on the reduced second preset trigger amount, return to step S610 to perform the thermal runaway test on each target battery cell again until thermal runaway does not occur in each target battery cell for the Nth time, and then end the cyclic thermal runaway test. It should be noted that N is a positive integer greater than or equal to 2.

[0143] For another example, for the thermal runaway triggering of the target battery cells triggered by heating, the sixth step increment can be set to 20 W. When performing the thermal runaway test on each target battery cell for the first time, if at least one group of the target battery cells experiences thermal runaway, the second preset trigger amount is reduced by 20 W, and based on the reduced second preset trigger amount, return to step S610 to perform the thermal runaway test on each target battery cell again until thermal runaway does not occur in each target battery cell for the Nth time, and then end the cyclic thermal runaway test. It should be noted that N is a positive integer greater than or equal to 2.

[0144] Step S650: When thermal runaway does not occur in each target battery cell, determine the last reduced second preset trigger amount as the thermal runaway trigger boundary amount.

[0145] For example, for the thermal runaway triggering of the target battery cells triggered by overcharging, when thermal runaway does not occur in each target battery cell, the thermal runaway trigger boundary amount (i.e., the optimal thermal runaway overcharging trigger amount) is the last reduced second preset trigger amount, that is, the optimal thermal runaway overcharging trigger amount = preset charging current * (1 - N * 10%). For another example, for the thermal runaway triggering of the target battery cells triggered by heating, when thermal runaway does not occur in each target battery cell, the thermal runaway trigger boundary amount (i.e., the optimal thermal runaway heating trigger amount) is the last reduced second preset trigger amount, that is, the optimal thermal runaway heating trigger amount = preset heating power - N * 20 W, achieving accurate testing of the trigger boundary of battery thermal runaway, and enabling more comprehensive, objective, and convenient research on battery thermal runaway characteristics, further improving the accuracy and reliability of the thermal runaway test of target battery cells.

[0146] In one embodiment, after the step of determining that thermal diffusion occurs in the battery pack to be tested when the pre-test characteristic information and the first test characteristic information of any one adjacent battery cell meet the first preset thermal runaway condition, it includes:

[0147] Based on the pre-test characteristic information and the first test characteristic information, obtain a thermal diffusion characteristic parameter table.

[0148] For example, repeated tests can be carried out under the same test conditions, and then multiple groups of pre-test characteristic information and first test characteristic information can be obtained to improve the accuracy and reliability of the obtained thermal diffusion characteristic data.

[0149] The thermal diffusion characteristic parameter table can be divided into different thermal diffusion characteristic parameter tables according to different thermal diffusion triggering methods. For example, the thermal diffusion characteristic parameter table includes the thermal diffusion characteristic parameter table triggered by overcharge and the thermal diffusion characteristic parameter table triggered by heating. Exemplarily, the thermal diffusion characteristic parameter table can include trigger time, whether thermal diffusion occurs, thermal diffusion trigger information, target cell information, air pressure information, etc. It should be noted that the trigger time refers to the time between the thermal runaway of the target cell and the thermal runaway of any adjacent cell; the determination condition for the occurrence of thermal diffusion is that after the thermal runaway of the target cell, the thermal runaway of any adjacent cell occurs.

[0150] Exemplarily, temperature-time (T-t) curves, voltage-time (V-t) curves, air pressure-time (V-t) curves, etc. are also generated according to the pre-test characteristic information, first test characteristic information, and second test characteristic information.

[0151] It should be understood that although Figures 2 to 6 the steps in the flowchart of Figures 2 to 6 are shown in sequence according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover,

[0152] In one embodiment, as Figure 7 shown, a battery thermal diffusion test system is also provided, including a processing device 710 and a test device 720; the test device 720 is used to fix the battery pack 730 to be tested, and the processing device 710 is connected to the test device 720 and the battery pack 730 to be tested; the processing device 710 is used to execute the steps of the battery thermal diffusion test method described in any one of the above.

[0153] Among them, for the specific descriptions of the test device 720, the battery pack 730 to be tested, and the processing device 710, please refer to the descriptions of the above embodiments and will not be repeated here.

[0154] By installing the battery pack 730 to be tested in the test device 720, the processing device 710 is respectively connected to the test device 720 and the battery pack 730 to be tested. The test device 720 can be used to collect test data such as the temperature and voltage of the battery pack 730 to be tested. The processing device 710 obtains the pre-test characteristic information of the battery pack 730 to be tested; the battery pack 730 to be tested includes a target battery cell and a plurality of adjacent battery cells; after controlling the target battery cell to trigger thermal runaway, the first test characteristic information of each corresponding adjacent battery cell is obtained; when the pre-test characteristic information and the first test characteristic information of any one of the corresponding adjacent battery cells meet the first preset thermal runaway condition, it is determined that the battery pack 730 to be tested has thermal diffusion, thereby realizing the thermal diffusion test of the battery pack 730 to be tested. In this application, it is not necessary to use the entire battery panel as a test sample for testing. Only a target battery cell and a plurality of adjacent battery cells are used, and the pre-test characteristic information of the target battery cell and the plurality of adjacent battery cells is obtained. By triggering thermal runaway of the target battery cell, the first test characteristic information of the adjacent battery cells is obtained, and then according to the pre-test characteristic information and the first test characteristic information, it is judged whether the battery pack 730 to be tested has thermal diffusion, which improves the accuracy and reliability of the thermal diffusion test result, and reduces the high test cost and the great test difficulty.

[0155] In one embodiment, the present application also provides a computer storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the battery thermal diffusion test method in any one of the above are realized.

[0156] For example, when the computer program is executed by a processor, the following steps are realized:

[0157] Obtain the pre-test characteristic information of the battery pack to be tested; the battery pack to be tested includes a target battery cell and a plurality of adjacent battery cells; after controlling the target battery cell to trigger thermal runaway, obtain the first test characteristic information of each corresponding adjacent battery cell; when the pre-test characteristic information and the first test characteristic information of any one of the corresponding adjacent battery cells meet the first preset thermal runaway condition, it is determined that the battery pack to be tested has thermal diffusion, thereby realizing the thermal diffusion test of the battery pack to be tested.

[0158] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above division operation methods. Among them, any reference to a memory, storage, database, or other medium used in the various embodiments provided in the present application can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0159] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0160] The above-described embodiments merely represent several implementation manners of the present application. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for testing battery thermal diffusion, characterized in that, The method includes the following steps: Obtain the pre - test characteristic information of the battery pack to be tested; the battery pack to be tested includes a target battery cell and several adjacent battery cells; After controlling the target battery cell to trigger thermal runaway, obtain the first test characteristic information of each corresponding adjacent battery cell; When the pre - test characteristic information and the first test characteristic information of any one of the corresponding adjacent battery cells satisfy the first preset thermal runaway condition, determine that thermal diffusion occurs in the battery pack to be tested.

2. The battery thermal diffusion test method according to claim 1, wherein The pre - test characteristic information includes the first pre - test sample state information; the first test characteristic information includes the first test temperature and the first post - test sample state information; The step of determining that thermal diffusion occurs in the battery pack to be tested when the pre - test characteristic information and the first test characteristic information of any one of the corresponding adjacent battery cells satisfy the first preset thermal runaway condition includes: When the rising rate of the first test temperature continuously exceeds the first threshold for the first preset time, and the comparison result between the first post - test sample state information and the first pre - test sample state information satisfies the first comparison condition, determine that thermal diffusion occurs in the battery pack to be tested.

3. The battery thermal diffusion test method according to claim 2, wherein, The first pre - test sample state information includes the first initial voltage, the initial mass, and the first initial explosion - proof valve image; the first post - test sample state information includes the first test voltage, the test mass, and the first test explosion - proof valve image; The judgment step for the comparison result between the first post - test sample state information and the first pre - test sample state information to satisfy the first comparison condition includes: The difference between the first test voltage and the first initial voltage exceeds the first voltage difference, the difference between the test mass and the initial mass exceeds the mass difference, or the feature matching difference between the first test explosion - proof valve image and the first initial explosion - proof valve image exceeds the first matching threshold.

4. The battery thermal diffusion test method according to claim 1, wherein Before the step of obtaining the first test characteristic information of each corresponding adjacent battery cell after controlling the target battery cell to trigger thermal runaway, it includes: Obtain the second test characteristic information of the target battery cell during the charging process or the heating process; When the pre - test characteristic information and the second test characteristic information satisfy the second preset thermal runaway condition, determine that the target battery cell has triggered thermal runaway.

5. The battery thermal diffusion test method according to claim 4, characterized in that The pre - test characteristic information of the target also includes the second pre - test sample state information; the second test characteristic information includes the second test temperature and the second post - test sample state information; The step of determining that the target battery cell has triggered thermal runaway when the pre - test characteristic information and the second test characteristic information satisfy the second preset thermal runaway condition includes: When the rising rate of the second test temperature continuously exceeds the second threshold for the second preset time, and the comparison result between the second post - test sample state information and the second pre - test sample state information satisfies the second comparison condition, determine that the target battery cell has triggered thermal runaway.

6. The battery thermal diffusion test method according to claim 5, wherein The battery pack to be tested is arranged in a test device, and the test device has a pressure - relief cavity; the second pre - test sample state information includes the second initial voltage and the initial pressure in the pressure - relief cavity; the second post - test sample state information includes the second test voltage, the test pressure in the pressure - relief cavity, and the test device pressure - relief valve image; The judgment step for the comparison result of the state information of the sample after the second test and the state information of the sample before the second test to meet the second comparison condition includes: The difference between the second test voltage and the second initial voltage exceeds the second voltage difference, the difference between the air pressure in the test pressure relief chamber and the initial air pressure in the pressure relief chamber exceeds the air pressure threshold, or the feature matching value of the image of the pressure relief valve of the test device exceeds the second matching threshold.

7. The battery thermal diffusion test method according to claim 6, characterized in that, It further includes the steps: Based on the preset height of the pressure relief chamber, perform thermal diffusion tests on at least two groups of battery packs to be tested; When thermal diffusion does not occur in each of the battery packs to be tested, increase the preset height of the pressure relief chamber based on the first step value, and perform thermal diffusion tests on each of the battery packs to be tested again according to the increased preset height of the pressure relief chamber until thermal diffusion occurs in any one of the battery packs to be tested; When thermal diffusion occurs in any one of the battery packs to be tested, determine the finally increased preset height of the pressure relief chamber as the target height of the pressure relief chamber.

8. The battery thermal diffusion test method according to claim 7, wherein After the step of performing thermal diffusion tests on at least two groups of battery packs to be tested based on the preset height of the pressure relief chamber, it includes: When thermal diffusion occurs in at least one of the battery packs to be tested, decrease the preset height of the pressure relief chamber based on the second step value, and perform thermal diffusion tests on each of the battery packs to be tested again according to the decreased preset height of the pressure relief chamber until thermal diffusion does not occur in each of the battery packs to be tested; When thermal diffusion does not occur in each of the battery packs to be tested, determine the finally decreased preset height of the pressure relief chamber as the target height of the pressure relief chamber.

9. The battery thermal diffusion test method according to any one of claims 1 to 8, characterized in that, It further includes the steps: Based on the first preset trigger amount, perform thermal diffusion tests on at least two groups of battery packs to be tested; When thermal diffusion does not occur in each of the battery packs to be tested, increase the first preset trigger amount based on the third step value, and perform thermal diffusion tests on each of the battery packs to be tested again according to the increased first preset trigger amount until thermal diffusion occurs in any one of the battery packs to be tested; When thermal diffusion occurs in any one of the battery packs to be tested, determine the finally increased first preset trigger amount as the thermal diffusion trigger boundary amount.

10. The battery thermal diffusion test method according to claim 9, wherein, After the step of performing thermal diffusion tests on at least two groups of battery packs to be tested based on the first preset trigger amount, it includes: When thermal diffusion occurs in at least one of the battery packs to be tested, decrease the first preset trigger amount based on the fourth step value, and perform thermal diffusion tests on each of the battery packs to be tested again according to the decreased first preset trigger amount until thermal diffusion does not occur in each of the battery packs to be tested; When thermal diffusion does not occur in each of the battery packs to be tested, determine the finally decreased first preset trigger amount as the thermal diffusion trigger boundary amount.

11. The battery thermal diffusion test method according to any one of claims 1 to 8, characterized in that It further includes the steps: Based on the second preset trigger amount, perform thermal runaway tests on at least two target battery cells; When thermal runaway does not occur in each of the target battery cells, increase the second preset trigger amount based on the fifth step value, and perform thermal runaway tests on each of the target battery cells again according to the increased second preset trigger amount until thermal runaway occurs in any one of the target battery cells; When thermal runaway occurs in any one of the target battery cells, the second preset trigger amount after the last increase is determined as the thermal runaway trigger boundary amount.

12. The battery thermal diffusion test method according to claim 11, wherein After the step of performing a thermal runaway test on at least two target battery cells based on the second preset trigger amount, it includes: When thermal runaway occurs in at least one of the target battery cells, the second preset trigger amount is decreased based on the sixth step value, and a thermal runaway test is performed on each of the target battery cells again according to the decreased second preset trigger amount until thermal runaway does not occur in any of the target battery cells; When thermal runaway does not occur in any of the target battery cells, the second preset trigger amount after the last decrease is determined as the thermal runaway trigger boundary amount.

13. The battery thermal diffusion test method according to claim 1, characterized in that After the step of determining that thermal diffusion occurs in the battery pack to be tested when the pre-test characteristic information and the first test characteristic information of any adjacent battery cell meet the first preset thermal runaway condition, it includes: According to the pre-test characteristic information and the first test characteristic information, a thermal diffusion characteristic parameter table is obtained.

14. A battery thermal diffusion test system, characterized in that It includes a processing device and a testing device; The testing device is used to fix the battery pack to be tested, and the processing device is connected to the testing device and the battery pack to be tested; The processing device is used to execute the steps of the battery thermal diffusion test method according to any one of claims 1 to 13.

15. A computer storage medium, on which a computer program is stored, characterized in that, When the computer program is executed by a processor, it implements the steps of the battery thermal diffusion test method according to any one of claims 1 to 13.

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