Battery Module Thermal Runaway Test Apparatus and Method

Abstract

This invention belongs to the field of power battery safety testing technology, and relates to a battery module thermal runaway testing device and method. The device includes multiple battery cells arranged sequentially along a predetermined direction, a heating unit located on one side of a target battery cell, a heat insulation structure located between the heating unit and adjacent battery cells, a limiting structure for maintaining a preset gap between battery cells, a temperature monitoring unit located at the center of the large surface of the battery cell, and a temperature control base located below the battery cell. The heating unit is in direct contact with the target battery cell, and the heat insulation structure is used to limit heat transfer to adjacent battery cells, thereby forming a directional heat diffusion path. The method includes pre-processing the battery cells, assembling the test module, triggering thermal runaway of the target battery cell and collecting voltage and temperature data, and determining the thermal runaway state through a linkage judgment condition of voltage drop, temperature, and temperature rise rate. It can verify the rationality of the battery cell gaps and thermal diffusion behavior while maintaining the authenticity of the module structure, reducing testing costs and shortening the test cycle.

Description

Technical Field

[0001] This invention belongs to the field of power battery safety testing technology, specifically relating to a battery module thermal runaway testing device and method. Background Technology

[0002] With the increasingly widespread application of power batteries in new energy vehicles and energy storage systems, battery thermal runaway and its thermal diffusion behavior within the module have become key factors affecting system safety. Therefore, it is usually necessary to build a thermal runaway simulation / triggering device during the product development stage to verify and test the cell triggering process and the heat propagation behavior between adjacent cells.

[0003] In existing technologies, one approach involves setting up a module cell to simulate the battery under test, and configuring a heating trigger device to heat the module cell. Simultaneously, a heating control device and a signal acquisition device collect signals such as cell temperature and voltage to determine the cell's state and obtain thermal runaway-related time parameters. For example, Chinese invention patent application publication number CN109888412A, filed on December 6, 2017, entitled "Battery System Thermal Runaway Simulation Device and Simulation Method," discloses a device including a module cell, a heating trigger device in close contact with the module cell, a heating control device, and a signal acquisition device electrically connected to the module cell. Temperature sensors and voltage sampling points are set on the module cell to collect temperature and voltage signals. The heating trigger device can be a heating rod and a housing structure arranged within the module's outer frame, and continuous heating simulates thermal runaway of the cell, thereby obtaining thermal runaway-related time information under specific scenarios.

[0004] Another approach focuses on the structural convenience and maintainability of the thermal runaway triggering component. For example, Chinese Utility Model Announcement No. CN222126707U, filed on March 19, 2024, entitled "A Thermal Runaway Triggering Component," discloses a component including a heating sleeve disposed between two adjacent battery cells. The heating sleeve extends along its height to form a receiving cavity, within which a heating device is disposed. A notch is provided on the side of the heating sleeve, communicating with the receiving cavity, so that the heating device can be pulled out or replaced through the notch. This allows for maintenance without disassembling the battery module in case of heating device failure, improving testing efficiency and reducing the cost of re-sample preparation. In addition, this approach also mentions that a heat insulation layer can be provided on the side of the heating sleeve near the non-target battery cell to reduce the impact on the non-target battery cell.

[0005] However, the aforementioned existing technologies focus more on the "heat-triggered thermal runaway" itself or the ease of structural maintenance of the triggering components, and still have shortcomings in module-level thermal diffusion simulation and verification. For example, when constructing the test device, insufficient consideration is given to key factors affecting thermal diffusion behavior, such as the coordinated arrangement of cell gaps, insulation and heating structures, and the directional control of heat propagation paths. This results in deviations between the test structure and the actual module state, making it difficult to evaluate the impact of cell gap design on the thermal diffusion process. At the same time, thermal runaway determination often relies on a single temperature threshold or phenomenon observation, making it difficult to achieve rapid and accurate determination and location of thermal runaway. Therefore, it is still necessary to provide a device and method that can achieve directional heat transfer and thermal diffusion process data acquisition while maintaining the authenticity of the module structure. Summary of the Invention

[0006] 1. The technical problem the invention aims to solve.

[0007] To address the technical problems in existing battery module thermal runaway testing, such as insufficient consistency between the test structure and the actual module state, difficulty in accurately reproducing cell gaps and insulation arrangement conditions, and deviations in heat transfer and diffusion paths that affect the accuracy of thermal diffusion assessment, this application provides a battery module thermal runaway testing device.

[0008] Furthermore, this application also provides a thermal runaway triggering and determination method based on the battery module thermal runaway test device, in order to solve the problems in the prior art where thermal runaway determination relies on a single threshold or phenomenon observation, and there is a lag in determination and inaccurate positioning.

[0009] 2. Technical Solution Based on the objectives of this invention, a first aspect of this invention provides a battery module thermal runaway testing device, comprising: At least three battery cells arranged sequentially along a predetermined direction; A heating unit is disposed on one side of one of the battery cells and is in direct contact with the battery cell; A heat insulation structure is disposed on the side of the heating unit away from the battery cell, and the heat insulation structure is located between the battery cell and another adjacent battery cell; The elastic limiting structure set around the large surface of each battery cell is used to maintain the preset gap between adjacent battery cells. A temperature sensor is located at the center of the large surface of the battery cell; Temperature control base in contact with the bottom of the battery cell; And a voltage monitoring unit for collecting the voltage of the battery cell.

[0010] According to any embodiment of the first aspect of the present invention, the battery module thermal runaway test device has 3 to 10 battery cells forming a small test module with a single parallel and multiple series structure.

[0011] By limiting the number of battery cells to 3 to 10, the test structure can have a more typical module arrangement, which is beneficial for observing the heat propagation behavior between multiple battery cells under limited volume and improving the representativeness of the heat diffusion test results.

[0012] Preferably, the number of battery cells is 5.

[0013] According to any embodiment of the first aspect of the present invention, the thermal runaway test device for a battery module is wherein the thermal insulation structure is an aerogel plate or an epoxy plate with a thickness of not less than 3 mm and an area not less than the area of ​​the heating unit, so as to ensure that the thermal insulation area completely covers the heat transfer path.

[0014] By setting up a heat insulation structure with a thickness of not less than 3mm and an area not less than that of the heating unit, the transfer of heat to non-target cells in adjacent cells can be effectively reduced, test interference can be reduced, and the stability of heat diffusion path control can be improved.

[0015] According to any embodiment of the first aspect of the present invention, the battery module thermal runaway testing device, wherein the elastic limiting structure is a loop-shaped frame structure disposed around the periphery of the large surface of the battery cell, the loop-shaped frame being composed of at least one of foam or silicone pad, for maintaining the stability of the battery cell gap after the clamp is fixed.

[0016] By setting an elastic loop frame structure around the large surface of the battery cell, the gap between the battery cells can be kept stable under clamping conditions, reducing the risk of gap changes caused by external vibration or stress rebound, thereby improving the consistency of test conditions.

[0017] According to any embodiment of the first aspect of the present invention, the battery module thermal runaway testing device is a temperature control base, which is a liquid cooling plate, and the liquid cooling plate is attached to the bottom of the battery cell by thermally conductive adhesive.

[0018] By setting a liquid cooling plate as a temperature control base, the temperature at the bottom of the battery cell can be adjusted in a timely manner after thermal runaway is triggered, which is beneficial to controlling the stability of the test environment and improving the repeatability of the test.

[0019] According to any embodiment of the first aspect of the present invention, in the battery module thermal runaway testing apparatus, the power of the heating unit is set according to the energy levels of the heated battery cell, wherein: When the cell energy E < 100Wh, the heating power is 30W to 300W; When 100Wh≤E<400Wh, the heating power is 300W~1000W; When 400Wh≤E<800Wh, the heating power is 300W~2000W; When E≥800Wh, the heating power is greater than 600W.

[0020] By setting the heating power according to the battery cell's energy level, batteries of different specifications can be stably triggered within a reasonable power range, thus improving the test's applicability and triggering efficiency.

[0021] Preferably, the temperature sensor is positioned at the center of the large surface of the battery cell to accurately represent the temperature of the battery cell body.

[0022] Preferably, the testing device is housed in a steel box with ventilation holes, and the gaps in the box are filled with refractory bricks.

[0023] Based on the objectives of this invention, a second aspect of this invention provides a method for testing thermal runaway of a battery module, using the aforementioned testing apparatus, comprising: Pre-treatment of the battery cells followed by charge-discharge cycles; The battery cells are assembled with preset gaps to form a testing device; The battery cells were charged and left to stand at the test ambient temperature; The heating unit is activated to heat the target battery cell; Temperature and voltage data are collected in real time using temperature sensors and voltage monitoring units; Determine whether thermal runaway has occurred based on preset linkage judgment conditions.

[0024] Preferably, the test environment temperature is (25±2)℃ or (45±2)℃.

[0025] Preferably, the preprocessing includes: Discharge at a constant current of 1 / 3C until the discharge termination voltage is reached; Let stand for 1 hour; Charge at a constant current of 1 / 3C until the charging termination voltage is reached, then switch to constant voltage charging until the current drops to 0.05C; Repeat the above steps three times and record the average discharge capacity C0 for the third discharge.

[0026] Preferably, the testing device uses liquid cooling to regulate the temperature of the large surface area of ​​the battery cell before heating, and then turns off the liquid cooling.

[0027] Preferably, the liquid cooling system is turned on immediately after the target cell triggers thermal runaway, with the liquid cooling water temperature at 25°C and the flow rate at 3.2L / min, and then turned off after 30 minutes.

[0028] According to any embodiment of the battery module thermal runaway test method of the second aspect of the present invention, the linkage determination condition satisfies any of the following conditions: The voltage drop exceeds 25% of the initial voltage, and the temperature rise rate is not less than 1℃ / s and lasts for more than 3s; or The temperature at the monitoring point reaches 60℃, and the temperature rise rate is not less than 1℃ / s and lasts for more than 3s.

[0029] By linking voltage drop, temperature threshold, and temperature rise rate for judgment, the risk of misjudgment caused by judging a single parameter can be avoided, thereby improving the accuracy and sensitivity of thermal runaway judgment.

[0030] Preferably, the test data sampling time interval is 1 second.

[0031] Preferably, after the test is completed, the voltage curve, temperature curve, thermal runaway time and thermal diffusion time of each cell are recorded.

[0032] According to any embodiment of the second aspect of the present invention, the battery module thermal runaway test method activates the liquid cooling system after the target cell triggers thermal runaway and shuts it off after a preset time.

[0033] By activating the liquid cooling system after thermal runaway is triggered in the target cell, it is helpful to control the changes in the overall temperature field during the test and reduce the additional impact of extreme temperature rise on other cells.

[0034] According to any embodiment of the second aspect of the present invention, in the battery module thermal runaway test method, if no thermal runaway occurs in any of the other cells besides the target cell, it is determined that no thermal diffusion has occurred; if at least one other cell experiences thermal runaway, it is determined that thermal diffusion has occurred.

[0035] By distinguishing whether thermal runaway has occurred in adjacent cells, it is possible to clearly identify whether thermal diffusion has occurred, thus providing an intuitive basis for assessing the safety of the module structure.

[0036] Any embodiment of any aspect of the present invention can be combined with other embodiments without contradiction. Furthermore, in any embodiment of any aspect of the present invention, any technical feature can be applied to the same technical feature in other embodiments without contradiction.

[0037] Without causing contradictions, any technical feature of any aspect or embodiment of the present invention is equally applicable to any other embodiment or embodiment of any other aspect. Of course, when applicable to each other, appropriate modifications may be made to the corresponding features as necessary. The various aspects and features of the present invention are further described below.

[0038] 3. Beneficial effects Compared with existing known technologies, the technical solution provided by this invention has the following beneficial effects: (1) The battery module thermal runaway testing device of this application achieves controllable construction of module-level heat transfer paths by constructing a controllable single-sided heating and adjacent-side heat insulation structure between multiple cells, combined with a preset gap maintenance structure between cells and a bottom temperature control base. This device can realistically reproduce the stress state and gap state of cells in the module structure without preparing a complete thermal runaway sample package, thereby more accurately simulating the heat propagation behavior between cells when thermal runaway occurs. Compared with existing devices that only focus on heating triggering or single-cell runaway simulation, the device of this application achieves directional control of the heat diffusion path at the structural level, which is conducive to obtaining temperature distribution and diffusion data that are closer to the actual module operating conditions, and improving the authenticity and reliability of the heat diffusion test. At the same time, the structure of this device is relatively simple, without the need for complex mold opening and complete system-level sample package production, which can significantly reduce test costs, shorten the test preparation cycle, and improve the efficiency of scheme verification.

[0039] (2) The battery module thermal runaway test method of this application collects cell voltage and temperature data in real time during the thermal runaway triggering process, and makes a comprehensive judgment based on the linkage judgment mechanism of voltage change, temperature threshold and temperature rise rate, thereby realizing rapid identification and accurate location of thermal runaway state. This method avoids the judgment lag problem caused by relying solely on a single temperature threshold or flame phenomenon observation, improves the sensitivity and accuracy of thermal runaway detection, and helps to achieve effective identification of the early stage of thermal runaway. At the same time, the method collects data and records time under unified test conditions, which can form a complete thermal diffusion process curve, providing reliable data support for the rationality verification of cell gap and thermal diffusion behavior analysis, which is conducive to accelerating the iterative optimization of module safety design and improving the comparability and production consistency between different schemes. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the arrangement of the large-area structure and limiting structure of the battery cell in the battery module thermal runaway test device in this application embodiment; Figure 2 This is a schematic diagram of the overall structure of the battery module thermal runaway test device in the embodiments of this application.

[0041] in: 1. Housing; 2. Battery cell; 2-1. First battery cell; 2-2. Second battery cell; 2-3. Third battery cell; 2-4. Fourth battery cell; 2-5. Fifth battery cell; 3. Silicone pad; 4. Foam; 5. Liquid cooling plate; 6. Clamp; 7. Refractory brick; 8. Thermally conductive adhesive; 9. Heat insulation pad; 10. Heating plate; 11. Temperature sensor. Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments.

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1 The battery module thermal runaway testing device and method of this embodiment are as follows: I. Device Structure like Figure 1 and Figure 2 As shown, this embodiment uses five square battery cells of the same specifications, arranged sequentially in the same direction to form a small module structure. The five battery cells are the first battery cell 2-1, the second battery cell 2-2, the third battery cell 2-3, the fourth battery cell 2-4, and the fifth battery cell 2-5, wherein the third battery cell 2-3 is used as the thermal runaway trigger.

[0045] A heating plate 10 is installed on one side of the third battery cell 2-3, and the heating plate is in direct contact with the large surface of the third battery cell. A heat insulation pad 9 is installed on the side of the heating plate away from the third battery cell, so that the heat insulation pad is located between the third battery cell and the second battery cell.

[0046] The preferred material for the heat insulation pad is aerogel board or epoxy board. In this embodiment, foam or silicone pads with heat insulation properties can also be used, with a thickness of 4 mm to 5 mm and an area not less than that of the heating plate.

[0047] An elastic U-shaped frame structure is set around the periphery of the large surface of each battery cell. In this embodiment, the U-shaped frame is composed of foam 4 and silicone pad 3, arranged close to the edge of the battery cell. Foam 4 provides overall elastic support, while silicone pad 3 improves contact stability and heat resistance. By combining the two elastic materials, the cell gap can be stably maintained and the vibration damping effect can be achieved simultaneously during the fixture fixing process, thereby improving the consistency and reliability of the test structure. After the module is fixed by the fixture 6, the gap between adjacent battery cells is re-measured, and the value is 2.5 mm.

[0048] A liquid cooling plate 5 is installed at the bottom of the battery cell, and thermally conductive adhesive 8 is used to ensure that the bottom surface of the battery cell is fully bonded to the liquid cooling plate. The entire device is placed inside a steel box 1, and the gaps inside the box are filled with refractory bricks 7.

[0049] Temperature sensor 11 is arranged at the center of the large surface of each cell, and voltage sampling line is arranged to collect voltage changes of each cell.

[0050] II. Cell Parameters The preferred dimensions of the battery cell are: thickness 40 mm to 70 mm, width 120 mm to 200 mm, and height 80 mm to 150 mm.

[0051] The rated capacity of the battery cell is preferably 50 Ah to 200 Ah. The energy of a single battery cell is preferably 150 Wh to 800 Wh.

[0052] III. Cell Pretreatment The following pretreatment was performed at an ambient temperature of 25±2 ℃: Discharge at a constant current of 1 / 3C until the discharge termination voltage is reached; let stand for 1 hour; charge at a constant current of 1 / 3C until the charging termination voltage is reached; switch to constant voltage charging until the current drops to 0.05C; repeat the above cycle 3 times; record the average discharge capacity C0 of the third discharge cycle as 95% to 105% of the rated capacity of the cell.

[0053] IV. Thermal runaway triggering process The module stabilized under static conditions at an ambient temperature of 25 ℃. The heating power was selected as 800 W based on the battery cell's energy capacity. After heating began, voltage and temperature data were collected in real-time at 1-second intervals.

[0054] The third battery cell is determined to have experienced thermal runaway when any of the following linkage determination conditions are met: (1) The voltage drop exceeds 25% of the initial voltage, and the temperature rise rate is ≥1℃ / s and lasts for more than 3s; or (2) The monitored temperature reaches 60℃, and the temperature rise rate is ≥1℃ / s and lasts for more than 3s.

[0055] The trigger time is 200 s to 500 s. Immediately after triggering, the liquid cooling system is turned on, with the liquid cooling water temperature at 25 ℃ and the flow rate at 3 L / min to 5 L / min, and then turned off after 30 min.

[0056] V. Test Results The thermal runaway time of the third cell was 600 s to 900 s. Did the second, fourth, and fifth cells experience thermal runaway? No. Did thermal propagation occur? No. Did deflagration or open flame occur? No.

[0057] This embodiment verifies the thermal runaway behavior of battery cells under conditions of unilateral heating and adjacent side insulation using the aforementioned test method. By acquiring voltage and temperature data in real time and determining the occurrence time and spread of thermal runaway based on a linkage judgment mechanism, it is used to determine whether thermal diffusion occurs under the current structural and gap conditions, and to obtain the temperature rise curve and time parameters of the thermal diffusion process.

[0058] Example 2 Based on the structure of Example 1, only the test environment temperature was changed.

[0059] The ambient temperature was set to 45±2 ℃. The remaining structure and operating procedures were the same as in Example 1. Thermal diffusion occurred: Yes.

[0060] This embodiment is used to analyze the effect of ambient temperature on thermal diffusion behavior.

[0061] This embodiment repeats the above test procedure under different ambient temperature conditions to verify the impact of ambient temperature changes on thermal runaway trigger time and thermal diffusion behavior. By comparing the voltage change curves and temperature rise rates under different temperature conditions, the degree of influence of ambient temperature on the thermal diffusion path and diffusion risk can be determined. The test results show that thermal diffusion is more likely to occur under higher ambient temperatures.

[0062] Example 3 Based on the structure of Example 1, only the cell gap was changed. Three gap conditions were set: gap A: 2.2 mm; gap B: 2 mm; gap C: 1.8 mm. All other test conditions remained the same.

[0063] Record the following separately: trigger time; temperature rise rate of adjacent cells; and whether thermal diffusion occurred.

[0064] The test results were as follows: Gap A: No thermal diffusion occurred; Gap B: No thermal diffusion occurred; Gap C: Thermal diffusion occurred.

[0065] This embodiment verifies the impact of cell gaps on the heat diffusion path. By varying the preset gaps between cells, the embodiment verifies the heat diffusion behavior under different gap conditions. By recording the thermal runaway trigger time, the temperature rise of adjacent cells, and whether heat diffusion occurs, the influence of cell gaps on the heat propagation path and diffusion risk is analyzed, providing a basis for the rational design of cell gaps. The test results show that the smaller the gap, the easier it is for heat diffusion to occur.

[0066] Comparative Example 1 Compared to Example 1, the heat insulation pad 9 is omitted. The rest of the structure and test conditions remain the same.

[0067] Does heat diffusion occur? Yes. Used to analyze the influence of insulation structure on the direction of heat propagation.

[0068] This comparative example, tested without the insulation structure, verifies the impact of the insulation structure on the direction and range of heat propagation. By comparing the test results of the comparative example, the role of the insulation structure in suppressing the heating of non-target battery cells can be analyzed. The test results show that heat diffusion is more likely to occur after the insulation structure is removed.

[0069] As can be seen from the above embodiments and comparative tests, the testing device provided in this application sets a heating unit on one side of the target cell and a heat insulation structure on the side of the adjacent cell, so that heat spreads along a preset direction. This allows it to simulate the thermal runaway triggering process under conditions that are closer to the actual module structure state, and to obtain data on the temperature rise and diffusion behavior of the adjacent cells.

[0070] Based on this, by changing test parameters such as ambient temperature or cell gap, the thermal diffusion behavior under different structural conditions can be compared and analyzed. This can be used to verify the rationality of the cell gap design and assess the thermal diffusion risk of the module, providing experimental basis for the structural safety optimization of battery modules.

Claims

1. A battery module thermal runaway testing device, characterized in that, include: At least three battery cells arranged sequentially along a predetermined direction; A heating unit is disposed on one side of one of the battery cells and is in direct contact with the battery cell; A heat insulation structure is disposed on the side of the heating unit away from the battery cell, and the heat insulation structure is located between the battery cell and another adjacent battery cell; The elastic limiting structure set around the large surface of each battery cell is used to maintain the preset gap between adjacent battery cells. A temperature sensor is located at the center of the large surface of the battery cell; Temperature control base in contact with the bottom of the battery cell; And a voltage monitoring unit for collecting the voltage of the battery cell.

2. The battery module thermal runaway testing device according to claim 1, characterized in that, The number of battery cells is 3 to 10.

3. The battery module thermal runaway testing device according to claim 1, characterized in that, The heat insulation structure is an aerogel board or epoxy board with a thickness of not less than 3mm and an area not less than the area of ​​the heating unit.

4. The battery module thermal runaway testing device according to claim 1, characterized in that, The elastic limiting structure is a loop-shaped frame structure disposed around the periphery of the large surface of the battery cell, and the loop-shaped frame is composed of at least one of foam or silicone pad.

5. The battery module thermal runaway testing device according to claim 1, characterized in that, The temperature control base is a liquid cooling plate.

6. The battery module thermal runaway testing device according to claim 1, characterized in that, The power of the heating unit is set according to the electrical energy of the heated battery cell.

7. A method for testing thermal runaway of a battery module, characterized in that, Using the battery module thermal runaway testing apparatus according to any one of claims 1-6, comprising: Pre-treatment of the battery cells followed by charge-discharge cycles; The battery cells are assembled with preset gaps to form a testing device; The heating unit is activated to heat the target battery cell; Temperature and voltage data are collected in real time using the temperature sensor and voltage monitoring unit. Determine whether thermal runaway has occurred based on preset linkage judgment conditions.

8. The method according to claim 7, characterized in that, The linkage determination condition satisfies any of the following conditions: The voltage drop exceeds 25% of the initial voltage, and the temperature rise rate is not less than 1℃ / s and lasts for more than 3s; or The temperature at the monitoring point reaches 60℃, and the temperature rise rate is not less than 1℃ / s and lasts for more than 3s.

9. The method according to claim 7, characterized in that, The liquid cooling system is activated after thermal runaway is triggered in the target cell and then shut down after a preset time.

10. The method according to claim 7, characterized in that, If no thermal runaway occurs in any of the cells other than the target cell, then thermal propagation is determined not to have occurred. If at least one other cell experiences thermal runaway, thermal propagation is determined to have occurred.

Images