Battery thermal runaway chain reaction test method and safety boundary judgment method

Abstract

The invention discloses a battery thermal runaway chain reaction test method and a safety boundary judgment method, and belongs to the technical field of battery safety. The method comprises the following steps: connecting a thermal runaway trigger circuit of a battery, and connecting the thermal runaway trigger circuit with a data acquisition circuit; triggering a battery thermal runaway chain reaction test; in the battery thermal runaway chain reaction test, selecting to start a heat compensation test according to the characteristic parameters of a battery diffusion object; collecting acquired data in the battery thermal runaway chain reaction test, and processing the data to obtain a spread battery absorption heat value and a heat value required by battery thermal runaway; and according to the collected data, the spread battery absorption heat value and the heat value required by the battery thermal runaway, analyzing to obtain the safety boundary of the battery thermal runaway chain reaction. According to the method, the thermal runaway chain reaction of the battery module in the actual use process is simulated and reproduced, and the safety boundary condition of the thermal runaway chain reaction of the battery can be quickly and accurately evaluated by accurately calculating the heat transfer process among the battery monomers.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery safety, and in particular relates to a battery thermal runaway chain reaction test method and a safety boundary determination method. Background Art

[0002] In recent years, the construction and planning of modern smart grid systems with lithium-ion battery energy storage technology and systems as the core have attracted increasing attention, and energy storage has been widely used in all aspects of power generation, transmission, distribution, and power consumption in power systems. Correspondingly, safety accidents in power energy storage systems have triggered widespread concern about lithium battery energy storage systems. In power energy storage systems, in order to meet the requirements for energy and working voltage, in actual applications, a large number of lithium-ion battery cells are often connected by circuits to form battery modules and battery clusters and then work in a unified manner. In these scenarios, if one of the battery cells has thermal runaway, the heat and open flames generated will violently heat the adjacent batteries and cause them to have thermal runaway, which will cause the entire battery module to have thermal runaway propagation behavior similar to the domino effect, and ultimately cause fires and explosions in the entire battery system. The combustion, explosion, and fire spread of batteries are due to the transfer of a large amount of heat between batteries.

[0003] Clarifying the safety boundary and propagation mechanism of battery thermal runaway plays a decisive role in battery protection design. However, current experimental research focuses on the research on thermal runaway at the battery monomer level triggered by different types and intensities of excitation sources. The research on thermal runaway diffusion tends to be a judgmental test on the module as a whole. There is still a lack of test evaluation methods and systems for the safety boundary of thermal runaway chain reactions of lithium-ion batteries for power storage in China. The research on thermal runaway chain reactions between battery modules is only at the simulation stage, but simulation experiments are difficult to simulate the randomness and heat changes of thermal runaway. There is a lack of quantitative simulation methods for flames and eruptions, and the established model is far from the actual situation.

[0004] The Chinese patent publication number CN112098865A, "An Experimental Method for Thermal Runaway Diffusion of Battery Cell Modules", discloses an experimental method for thermal runaway diffusion of battery cell modules. The experimental method for thermal runaway diffusion of the battery cell module includes preparing a battery cell module to be tested, the battery cell module to be tested includes at least a first module and a second module, adjacent battery cells in the first module are insulated, and the tabs of multiple battery cells are connected in series, and heat is transferred between adjacent battery cells in the second module, and the tabs of multiple battery cells are disconnected. Thermal runaway experiments are performed on the battery cell modules to be tested respectively, and curves of temperature changes over time of each battery cell in the first module and the second module are obtained. By comparing the obtained curves of temperature changes over time of the first module and the second module, the thermal runaway diffusion path of the battery cell module to be tested is determined. This solution can analyze the coupling effect of electricity and heat on thermal runaway during the diffusion process by comparing the thermal runaway diffusion phenomenon of two types of battery modules. However, this method can only compare the temperature change phenomenon, lacks analysis of the electrical characteristics of the runaway module, lacks quantitative research methods, and cannot cover all-factor analysis. At the same time, this method does not provide a stable experimental method to trigger the thermal runaway diffusion, and lacks reproducibility.

[0005] The Chinese patent publication number CN110083871A is "A thermal runaway simulation method and device based on a thermal runaway prediction model for lithium-ion batteries". This method uses the SOC (remaining power) and SOH (health level) of lithium-ion batteries and establishes a thermal runaway prediction model for lithium-ion batteries based on the heat generation mechanism of lithium-ion batteries. The thermal runaway prediction model of lithium-ion batteries is then used to calculate the instantaneous heat generation power of the corresponding lithium-ion batteries. The temperature, resistance value of the heat generation element and output current value of the control unit are collected by simulating heat generation through the electronically controlled heat generation element of the control unit to calculate the instantaneous heat generation power of the simulated heat generation. The instantaneous heat generation power of the simulated heat generation is compared with the instantaneous heat generation power of the lithium-ion battery calculated by the thermal runaway prediction model of the lithium-ion battery to complete the accurate simulation of the thermal runaway process of the lithium-ion battery. This scheme takes into account the influence of the battery SOC and SOH on the thermal runaway process and accurately simulates the heat generation process, but only considers the integral accumulation of the instantaneous heat generation power, and does not consider the influence of flames and eruptions. This simulation method also realizes the forward analysis of the safety boundary of the battery thermal runaway diffusion. Summary of the invention

[0006] The purpose of the present invention is to provide a battery thermal runaway chain reaction test method and a safety boundary determination method to address the above-mentioned problems in the prior art. The present invention simulates and reproduces the battery module thermal runaway chain reaction in actual use, and by accurately calculating the heat transfer process between battery cells, the safety boundary of the battery thermal runaway chain reaction can be quickly and accurately evaluated.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: In a first aspect, the present invention provides a battery thermal runaway chain reaction test method, comprising: Connect the thermal runaway trigger circuit of the battery, and connect the thermal runaway trigger circuit to the data acquisition circuit; Trigger battery thermal runaway chain reaction test; In the battery thermal runaway chain reaction test, the supplementary heating test is selected according to the characteristic parameters of the battery diffusion object; Collect the data collected in the battery thermal runaway chain reaction test, process the data, and obtain the heat value absorbed by the spreading battery and the heat value required for the battery thermal runaway; Based on the collected data, the heat value absorbed by the spreading battery, the heat value required for the battery to thermal runaway, and the threshold value of the number of battery cells that trigger thermal runaway due to heating, the safety boundary of the battery thermal runaway chain reaction is analyzed and obtained.

[0008] As a further improvement of the present invention, the battery meets the following requirements: completing rated power initialization charging until the battery energy state reaches 100%, and being left alone for more than 12 hours.

[0009] As a further improvement of the present invention, the battery and the heating plate are pre-tightened and clamped by clamping plates, specifically: a plurality of batteries are abutted and arranged between the clamping plates, the inner walls of the clamping plates are provided with heat insulation cotton, and a heating plate is provided on one side of each battery.

[0010] As a further improvement of the present invention, the thermal runaway trigger circuit connected to the battery includes: Install the upper cover plate and fix it directly above the battery, with the spacing distance consistent with the actual battery module / battery cluster structure; The heating plate is connected to the power cable, and the connecting cable is wrapped with fireproof wrap; The heating plate is connected to the power cable, and the connecting cable is wrapped with fireproof wrap; The electric ignition device is fixed above the center of each heating battery, and the cable of the electric ignition device is treated with fireproof coating.

[0011] As a further improvement of the present invention, in the connecting of the thermal runaway trigger circuit with the data acquisition circuit, the data acquisition circuit is connected to a thermal runaway acquisition device circuit, and the data acquisition device is a voltage, temperature acquisition system and a video acquisition system.

[0012] As a further improvement of the present invention, the battery thermal runaway chain reaction test is to trigger the battery thermal runaway by heating assisted by electric ignition to carry out a battery module thermal runaway chain reaction test.

[0013] As a further improvement of the present invention, the battery thermal runaway chain reaction test is specifically comprised of: Start the heating plate and continuously observe the temperature and voltage of the heating battery; After the battery safety valve breaks, use a pulse igniter until the smoke is ignited; After the voltage of a certain heating battery drops, turn off the heating plate on the side of the battery away from the spread until the voltage of the last heating battery drops.

[0014] As a further improvement of the present invention, the method of selecting to start the supplementary heating test according to the characteristic parameters of the battery diffusion object includes: Continue to observe the temperature between the supplementary heating plate and the diffusion battery. When the temperature shows a downward trend but the battery has not yet thermally runaway, start the supplementary heating plate to provide heat to the diffusion battery until the voltage drops.

[0015] As a further improvement of the present invention, the method of collecting the collected data in the battery thermal runaway chain reaction test, performing data processing, and obtaining the heat value required for the battery thermal runaway; comprises: Record the reheating time, and calculate the heat value ΔH absorbed by the spreading battery and the heat value W required for battery thermal runaway according to the reheating calculation model.

[0016] As a further improvement of the present invention, the heat supplement calculation model includes: ΔH=Mbatteries×Cp×(T-T0) / 1000; W = P·t / 1000*α; In the formula, ΔH is the battery enthalpy change, that is, the absorbed heat; Mbattery is the mass of the battery cell; Cp is the battery specific heat capacity; W is the amount of supplementary heat; P is the power of the supplementary heating plate; t is the supplementary heating time; α is the heat transfer efficiency of the heating plate.

[0017] As a further improvement of the present invention, the safety boundary of the battery thermal runaway chain reaction is analyzed based on the heat value absorbed by the propagating battery and the heat value required for the battery thermal runaway, as well as the threshold value determined by the number of battery cells that trigger thermal runaway by heating, and then analyzed, including: Obtain the number of heated batteries, the temperature during heating, the heating time, the amount of heat absorbed before heating, the amount of heating, the amount of heat absorbed when thermal runaway is triggered, and whether thermal runaway propagation occurs; Draw the correlation curve between the temperature during heating and the number of heated batteries, the correlation curve between the heat absorbed by the battery before heating and the number of heated batteries, the correlation curve between the heating time and the number of heated batteries, and the correlation curve between the heating amount and the number of heated batteries; The threshold for determining the number of battery cells that need to be heated simultaneously to trigger thermal runaway is obtained by extrapolating the curve, and then the safety boundary of the battery thermal runaway chain reaction is analyzed.

[0018] In a second aspect, the present invention provides a method for determining a battery thermal runaway chain reaction safety boundary, comprising: Obtain the number of heated batteries, the temperature during heating, the heating time, the amount of heat absorbed before heating, the amount of heating, the amount of heat absorbed when thermal runaway is triggered, and whether thermal runaway propagation occurs; Draw the correlation curve between the temperature during heating and the number of heated batteries, the correlation curve between the heat absorbed by the battery before heating and the number of heated batteries, the correlation curve between the heating time and the number of heated batteries, and the correlation curve between the heating amount and the number of heated batteries; The threshold for determining the number of battery cells that need to be heated simultaneously to trigger thermal runaway is obtained by extrapolating the curve, and then the safety boundary of the battery thermal runaway chain reaction is analyzed.

[0019] The heat supplement is calculated based on the heat supplement calculation model to calculate the heat value ΔH absorbed by the propagating battery and the heat value W required for the battery thermal runaway; the heat supplement calculation model includes: ΔH=Mbatteries×Cp×(T-T0) / 1000; W = P·t / 1000*α; In the formula, ΔH is the battery enthalpy change, that is, the absorbed heat; Mbattery is the mass of the battery cell; Cp is the battery specific heat capacity; W is the amount of supplementary heat; P is the power of the supplementary heating plate; t is the supplementary heating time; α is the heat transfer efficiency of the heating plate.

[0020] In a third aspect, the present invention provides a battery thermal runaway chain reaction safety boundary determination system, characterized in that it includes: An acquisition module is used to obtain the number of heated batteries, the temperature during heating, the heating time, the amount of heat absorbed before heating, the amount of heat, the amount of heat absorbed when thermal runaway is triggered, and whether thermal runaway propagation occurs; A drawing module is used to draw a correlation curve between the temperature during heating and the number of heated batteries, a correlation curve between the heat absorbed by the battery before heating and the number of heated batteries, a correlation curve between the heating time and the number of heated batteries, and a correlation curve between the amount of heating heat and the number of heated batteries; The analysis module is used to obtain the threshold value for the number of battery cells that need to be heated simultaneously to trigger thermal runaway through the curve extrapolation method, and then analyze and obtain the safety boundary of the battery thermal runaway chain reaction.

[0021] In a fourth aspect, the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method for determining the safety boundary of a battery thermal runaway chain reaction when executing the computer program.

[0022] In a fifth aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for determining the safety boundary of a battery thermal runaway chain reaction is implemented.

[0023] In a sixth aspect, the present invention provides a computer program product, which includes computer instructions, and is characterized in that the computer instructions instruct a computer to execute the battery thermal runaway chain reaction safety boundary determination method.

[0024] The beneficial effects of the present invention compared with the prior art are as follows: The present invention can simulate and reproduce the thermal runaway chain reaction in the actual energy storage system, quantitatively evaluate the risk level of thermal runaway diffusion of the battery, and clarify the safety boundary of triggering the thermal runaway diffusion of the battery. Compared with the existing research on triggering thermal runaway of battery cells and analyzing the thermal runaway diffusion in the battery pack, the present invention uses different numbers of battery cells to trigger, and takes a single diffusion battery cell as the observation object to simulate the thermal runaway diffusion and propagation in actual operation. For the test in which the propagation object is not out of control, the heat value required for the thermal runaway of the battery is obtained by the method of supplementary heat. Then, the threshold is determined based on the amount of supplementary heat obtained in the test and the number of battery cells that trigger thermal runaway by heating, and then the safety boundary of the thermal runaway chain reaction of the battery is analyzed. It can simulate and reproduce the thermal runaway chain reaction of the battery in the actual energy storage system, quantitatively evaluate the risk level of thermal runaway diffusion of the battery, and clarify the safety boundary of triggering the thermal runaway diffusion of the battery. This is of great significance for improving the overall safety of the energy storage system and promoting the continuous advancement of battery technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the embodiments of the present invention or the drawings of related technical solutions in the prior art are introduced below. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 This is a flow chart of the battery thermal runaway chain reaction test of the present invention; Figure 2 It is a schematic diagram of the arrangement of the test bench and the battery arrangement of the present invention; Figure 3 This is the thermal runaway image of the battery of the present invention; Figure 4 Battery surface temperature curve; Figure 5 Diagram showing the internal components and temperature sensor locations of the test battery module; Figure 6 Battery thermal runaway images; Figure 7 Battery surface temperature curve; Figure 8 Diagram showing the internal components and temperature sensor locations of the test battery module; Fig. 9 Battery thermal runaway images; Fig.10 Battery surface temperature curve. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limitations of the present invention. For the step numbers in the following embodiments, they are only provided for the convenience of explanation, and the order between the steps is not limited in any way, and the execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0028] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0029] Currently, there is a lack of testing and evaluation methods for the boundaries of thermal runaway chain reactions in lithium-ion batteries used for electric energy storage. The thermal runaway propagation model established based on simulation software is significantly different from the actual situation because it cannot take into account the randomness of flame roasting and high-temperature smoke injection.

[0030] The present invention provides a battery thermal runaway chain reaction test method, comprising: S1, connect the thermal runaway trigger circuit of the battery, and connect the thermal runaway trigger circuit with the data acquisition circuit; Test connection and triggering: Connect the battery's thermal runaway trigger circuit and data acquisition circuit. This step ensures that the battery status can be monitored in real time during the test and the battery's thermal runaway can be accurately triggered.

[0031] S2, triggering battery thermal runaway chain reaction test; The thermal runaway of batteries in actual energy storage systems is simulated through specific triggering methods (such as heating to induce thermal runaway assisted by electric ignition).

[0032] S3, in the battery thermal runaway chain reaction test, select to start the supplementary heating test according to the characteristic parameters of the battery diffusion object; Selection of supplementary heat test: In the thermal runaway chain reaction test, the supplementary heat test is selectively started according to the characteristic parameters of the battery diffusion object (such as voltage, temperature, etc.). This step is to further simulate the thermal runaway diffusion of the battery under different conditions, so as to more accurately evaluate its safety.

[0033] S4, collecting data collected in the battery thermal runaway chain reaction test, performing data processing, and obtaining the heat value absorbed by the propagating battery and the heat value required for the battery thermal runaway; Data collection and processing: During the test, the data collection circuit collects the battery's thermal runaway chain reaction data, including key parameters such as temperature and voltage. These data are processed to calculate the heat value absorbed by the spreading battery and the heat value required for the battery to thermally runaway. These data are crucial for assessing the risk of thermal runaway spreading of the battery.

[0034] S5, based on the collected data, the heat value absorbed by the spreading battery, the heat value required for the battery to thermally runaway, and the number of battery cells that trigger thermal runaway due to heating, the threshold is determined, and then the safety boundary of the battery thermal runaway chain reaction is analyzed.

[0035] Determination of safety margin: Based on the collected data, the heat value absorbed by the spreading battery and the heat value required for the battery thermal runaway, combined with the voltage and temperature characteristics of the battery to be spread, the safety margin of the battery thermal runaway diffusion is determined. This step provides an important basis for the safety design of the battery.

[0036] The present invention can more accurately evaluate the safety of batteries in real environments by simulating and reproducing the thermal runaway chain reaction of batteries in actual energy storage systems. This is of great significance for improving the overall safety of energy storage systems. By establishing a test and evaluation method for the boundary of thermal runaway chain reactions, the present invention can quantitatively evaluate the risk level of thermal runaway diffusion of batteries. This helps to promptly discover potential safety hazards and take corresponding preventive measures. The present invention clarifies the safety boundary that triggers the diffusion of thermal runaway of batteries through test data and heat supplementation calculation models. This provides clear guidance for the safety design of batteries and helps to design safer and more reliable battery products.

[0037] The present invention also provides a battery thermal runaway chain reaction boundary test evaluation method and a heat supplement calculation model, which simulates and reproduces the thermal runaway chain reaction in the actual energy storage system based on the triggering mode of heating different numbers of batteries to cause thermal runaway and igniting with electric ignition, and determines the thermal runaway trigger boundary according to the voltage and temperature characteristics of the diffusion object battery. In addition, the present invention establishes a heat supplement calculation model based on the test collection data to provide a basis for subsequent battery safety design.

[0038] This method can simulate and reproduce the thermal runaway chain reaction in the actual energy storage system by establishing a test and evaluation method for the thermal runaway chain reaction boundary and a heat compensation calculation model, quantitatively evaluate the risk level of battery thermal runaway diffusion, and clarify the safety boundary that triggers the battery thermal runaway diffusion.

[0039] This technology has broad application prospects. In the field of energy storage safety testing and evaluation, this invention provides a highly feasible, reproducible, and practical testing solution to address the lack of a test and evaluation method for the triggering boundary of thermal runaway chain reactions in lithium-ion batteries for electric energy storage.

[0040] In the field of energy storage safety design, based on the test scheme and heat compensation calculation model of the present invention, the safety boundary of battery thermal runaway diffusion can be clarified, and the energy required for battery thermal runaway diffusion can be comprehensively analyzed from the perspective of electrothermal coupling, so as to propose targeted thermal runaway protection measures, improve battery safety, and enhance the reliability of energy storage systems.

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] The present invention provides a battery thermal runaway chain reaction boundary test evaluation method and a heat supplement calculation model. The battery module thermal runaway chain reaction in actual use is simulated and reproduced, the heat transfer process between battery cells is accurately calculated, and the battery thermal runaway chain reaction safety boundary situation is quickly and accurately evaluated.

[0043] Figure 1 Battery thermal runaway chain reaction test flow chart, the present invention adopts the following technical solutions to achieve: Step 1: Prepare the battery and test bench, and connect the thermal runaway trigger circuit and the data acquisition circuit.

[0044] The battery module thermal runaway chain reaction test preparation in step 1 above includes sample preparation: 1) All test batteries are charged at rated power according to GB / T 36276 until the battery energy state reaches 100%, and are left for more than 12 hours; According to the test requirements Figure 2 The test bench and battery are arranged as shown; Figure 3 This is a schematic diagram of the test bench and battery layout; 2) In order to simulate the actual state of the energy storage system and ensure that the battery and the heating plate are in full contact, the sample and the heating plate need to be pre-tightened and clamped by a clamp.

[0045] Specifically, Figure 2 As shown, a plurality of batteries are arranged close together between the clamping plates, the inner walls of the clamping plates are provided with heat insulation cotton, and a heating plate is provided on one side of each battery.

[0046] Further, the battery module thermal runaway chain reaction test preparation in step 1 includes the thermal runaway trigger device circuit connection: The upper cover is set in advance to simulate the structural design of the battery in the actual application scenario, and the influence of flame jet on the diffusion of thermal runaway is further considered and normalized in the test method; the upper cover is fixed directly above the battery, and the spacing distance is consistent with the actual battery module / battery cluster structure.

[0047] 1) The heating plate is connected to the power cable, and the connecting cable is wrapped with fireproof wrap; 2) The heating plate is connected to the power cable, and the connecting cable is wrapped with fireproof wrap; 3) The electric ignition device is fixed above the center of each heating battery, and the cable of the electric ignition device is treated with fireproof coating.

[0048] Furthermore, the battery module thermal runaway chain reaction test preparation in step 1 includes the line connection of the thermal runaway acquisition device. The data acquisition device in the present invention is a voltage, temperature acquisition system and a video acquisition system.

[0049] Step 2: Conduct a battery module thermal runaway chain reaction test by using heating assisted by electric ignition to trigger battery thermal runaway.

[0050] The battery module thermal runaway chain reaction test operation process in step 2 above specifically includes: 1) Start the heating thermal runaway heating plate (referred to as: heating plate) and continuously observe the temperature and voltage of the heating battery; 2) After the battery safety valve breaks, use a pulse igniter until the smoke is ignited; 3) After the voltage of a certain heating battery drops, turn off the heating plate on the side away from the spreading battery until the voltage of the last heating battery drops; Note: Voltage drop refers to the phenomenon of a sudden and sharp drop in voltage in the circuit. If the voltage exceeds a certain threshold through real-time data observation, it is considered to be a sudden and sharp drop.

[0051] Step 3: Determine whether to start the supplementary heat test based on the characteristic parameters of the diffusion object.

[0052] The test data recording and processing in step 3 above includes: Continuously observe the temperature T between the heating plate and the diffusion battery p When the temperature shows a downward trend and the battery is still not in thermal runaway, the heating plate is started to heat the battery until the voltage drops.

[0053] Step 4: Process the test data based on the temperature data and video collected during the test, including the thermal runaway diffusion time, supplementary heating time, and supplementary heating amount.

[0054] The test data recording and processing in step 4 above includes: Record the heating time, calculate the enthalpy change of the battery's heat absorption process, that is, the absorbed heat value, and obtain the heat value required for battery thermal runaway through the heating method.

[0055] Table 1 Heat supplement calculation model

[0056] Step 5: Determine the safe margin of thermal runaway diffusion of the battery based on the test results, or add a single battery and repeat steps 1 to 4.

[0057] The test treatment in step 5 above includes, The number of heated batteries, Tp during heating (℃), heating time (min), heat absorbed before heating (KJ), amount of heating (KJ), heat absorbed when thermal runaway is triggered (KJ), and whether thermal runaway propagation occurs.

[0058] And plot the temperature T when adding heat p Correlation curve with the number of heated batteries, correlation curve between the heat absorbed by the battery before heating and the number of heated batteries, correlation curve between the heating time and the number of heated batteries, correlation curve between the amount of heating heat and the number of heated batteries; The extrapolation method of the curve can be used to obtain the threshold value for the number of battery cells that need to be heated simultaneously to trigger thermal runaway under this structure for thermal runaway diffusion to occur, and then the safety boundary of the battery thermal runaway chain reaction can be analyzed.

[0059] If the test results require retesting, add another single cell and repeat steps 1 to 4.

[0060] The embodiment of the present invention also provides a battery thermal runaway chain reaction heat supplement calculation model, specifically: calculate the enthalpy change of the battery endothermic process, that is, the absorbed heat value, and obtain the heat value required for the battery thermal runaway through the heat supplement method. The influence of the number of heated batteries in the battery thermal propagation process on the time and thermodynamics of the subsequent thermal runaway propagation is obtained through a simplified model calculation. The heat supplement calculation model is as follows:

[0061] The embodiment of the present invention also provides a method for determining the safety boundary of a battery thermal runaway chain reaction, the principle of which includes: Record the number of heated batteries, Tp (℃) during heating, heating time (min), heat absorption before heating (KJ), amount of heat absorption (KJ), heat absorption triggered by thermal runaway (KJ), and whether thermal runaway propagation occurs. Draw the correlation curve between temperature Tp during heating and the number of heated batteries, the correlation curve between the amount of heat absorbed by the battery before heating and the number of heated batteries, the correlation curve between the heating time and the number of heated batteries, and the correlation curve between the amount of heat absorption and the number of heated batteries. The threshold for determining the number of battery cells that need to be heated simultaneously to trigger thermal runaway under this structure can be obtained by extrapolating the curve, and then the safety boundary of the battery thermal runaway chain reaction can be analyzed.

[0062] The present invention carries out the following test process for the above scheme: 1-1 Test: Test the internal components of the battery module and the location of the temperature sensor. Figure 1 and Figure 2 As shown, the battery module consists of two batteries, plywood insulation cotton, and two heating plates, wherein the two batteries are a thermal runaway battery and a supplementary heating battery, respectively, the two heating plates are a battery heating plate and a battery supplementary heating plate, and the thermocouples are distributed on each side of the battery.

[0063] Figure 3 is the battery surface temperature curve. Figure 4 As shown, the battery status is: at 0s, the heating plate is turned on to heat the heating battery, and the battery surface temperature continues to rise; at 969s, the heating battery safety valve breaks, T2 slightly decreases, and the temperature on the other side of the heating battery is 80°C. At 3340s, T2 reaches the highest temperature of 240°C, and then continues to decrease. At 3752s, the heating battery is heated, and T3 continues to rise. At 3950s, the heating battery safety valve is opened, and the gas released by the heating battery is ignited by the heating battery flame, and the heating battery continues to burn.

[0064] Battery heat conduction heat Q The heat conduction calculation formula is as follows

[0065] Where: k is the thermal conductivity coefficient of the sample in a single direction. In this work, the thermal conductivity system of the normal direction of the large surface of the battery is taken as 0.61W / (m×K); A is the heat conduction area. For a 280Ah battery, A is 0.02782m2. D is the heat transfer distance. Assuming that the heat transfer distance is from the battery surface to the other side, D is the battery thickness, that is, 0.071m. T1 is the upstream thermal runaway battery temperature, and T is the battery body temperature.

[0066] The calculation shows that the heat transfer of the spreading battery through the heating battery is 52.73 kJ. The time from heating to safety valve opening is 198 s. According to the calculation that the heat transfer efficiency of the heating plate to the lithium iron phosphate battery is 75%, the battery is heated by 59.4 kJ, and the heat transfer and heating energy of the battery valve opening is 58.14 kJ.

[0067] 2-1 Test: Test the internal components of the battery module and the location of the temperature sensor. Figure 5 As shown, the battery module consists of 3 batteries, plywood insulation cotton, and 3 heating plates, two of which are heating-induced thermal runaway batteries and one is a supplementary heating battery, two heating plates are battery heating plates and one is a battery supplementary heating plate, and thermocouples are distributed on each side of the battery.

[0068] Figure 6 is the battery surface temperature curve. Figure 6 and Figure 7 As shown, the battery status is: at 0s, the heating plate is turned on to heat the heating battery, and the battery surface temperature continues to rise; at 1501s, the safety valve of heating battery 1 breaks, and the temperature of T2 is 138°C at this time; at 1876s, the safety valve of heating battery 2 breaks, and the temperature of T2 is 159°C at this time. T2 drops slightly, and the temperature on the other side of the heating battery is 80°C. At this time, the temperature of the spreading battery is lower than the self-heating temperature. At 3505s, the safety valve of the supplementary heating battery opens, and no supplementary heating is performed at this time. At this time, the temperature of T6 is 149°C. The highest temperature reached by T6 is 254°C. It is calculated that the heat transfer energy of the supplementary heating battery before opening the valve is 59.45kJ.

[0069] 3-1 Test: Test the internal components of the battery module and the location of the temperature sensor. Figure 8 As shown, the battery module consists of 5 batteries, plywood insulation cotton, and 5 heating plates, of which 4 batteries are thermal runaway batteries and 1 is a supplementary heating battery, 4 heating plates are battery heating plates and 1 is a battery supplementary heating plate, and thermocouples are distributed on each side of the battery.

[0070] according to Fig. 9 and Fig.10 As shown in the figure, the battery status is: at 0s, the heating plate is turned on to heat the heating battery, and the battery surface temperature continues to rise; at 2727s, the heating battery safety valve breaks, and the temperature of T2 is 150℃ at this time. At 2744s, the flame is ignited and the battery begins to burn. At 2788s, another heating battery safety valve is observed to open, and a jet fire phenomenon is generated. At 5240s, the supplementary heating battery safety valve opens, and no supplementary heating is performed at this time. The heat transfer energy received by the supplementary heating battery before the valve opens is calculated as The safety valve of heating battery 2 is broken. At this time, the temperature of T2 is 159℃. T2 decreases slightly. At this time, the temperature of the other side of the heating battery is 80℃. At this time, the temperature of the spreading battery is lower than the self-heating temperature. At 3505s, the safety valve of the supplementary heating battery opens. At this time, no supplementary heating is performed. At this time, the temperature of T6 is 149℃. The highest temperature of T6 is 254℃. The heat transfer energy of the supplementary heating battery before the valve is opened is calculated to be 12.697kJ.

[0071] Comparative analysis shows that it takes 2981s from the opening of the heating battery safety valve to the opening of the supplementary heating battery valve at 1-1, 2000s from the opening of the heating battery safety valve to the opening of the supplementary heating battery valve at 2-1, and 2513s from the opening of the heating battery safety valve to the opening of the supplementary heating battery valve at 4-1. From the heat transfer, it is found that the heating battery safety valve receives 58.14kJ of heat transfer energy before opening at 1-1, 59.45kJ of heat transfer energy before opening at 2-1, and 12.697kJ of heat transfer energy before opening at 2-1.

[0072] The present invention provides a battery thermal runaway chain reaction safety boundary determination system, comprising: An acquisition module is used to obtain the number of heated batteries, the temperature during heating, the heating time, the amount of heat absorbed before heating, the amount of heat, the amount of heat absorbed when thermal runaway is triggered, and whether thermal runaway propagation occurs; A drawing module is used to draw a correlation curve between the temperature during heating and the number of heated batteries, a correlation curve between the heat absorbed by the battery before heating and the number of heated batteries, a correlation curve between the heating time and the number of heated batteries, and a correlation curve between the amount of heating heat and the number of heated batteries; The analysis module is used to obtain the threshold value for the number of battery cells that need to be heated simultaneously to trigger thermal runaway through the curve extrapolation method, and then analyze and obtain the safety boundary of the battery thermal runaway chain reaction.

[0073] The system is based on the above-mentioned battery thermal runaway chain reaction safety boundary determination method.

[0074] The third object of the embodiment of the present invention is to provide an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the battery thermal runaway chain reaction safety boundary determination method when executing the computer program. It also includes a communication interface and a bus.

[0075] A fourth objective of an embodiment of the present invention is to provide a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for determining the safety boundary of a battery thermal runaway chain reaction is implemented.

[0076] A fifth objective of an embodiment of the present invention is to provide a computer program product, which includes computer instructions, and is characterized in that the computer instructions instruct a computer to execute the battery thermal runaway chain reaction safety boundary determination method.

[0077] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0078] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0079] The present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, readable storage media, optical storage, etc.) containing computer-usable program codes.

[0080] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0081] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A battery thermal runaway chain reaction test method, characterized in that: include: Connect the thermal runaway trigger circuit of the battery, and connect the thermal runaway trigger circuit to the data acquisition circuit; Trigger battery thermal runaway chain reaction test; In the battery thermal runaway chain reaction test, the supplementary heating test is selected according to the characteristic parameters of the battery diffusion object; Collect the data collected in the battery thermal runaway chain reaction test, process the data, and obtain the heat value absorbed by the spreading battery and the heat value required for the battery thermal runaway; Based on the collected data, the heat value absorbed by the spreading battery, the heat value required for the battery to thermal runaway, and the threshold value of the number of battery cells that trigger thermal runaway due to heating, the safety boundary of the battery thermal runaway chain reaction is analyzed and obtained.

2. A battery thermal runaway chain reaction test method according to claim 1, characterized in that: The battery meets the following requirements: complete rated power initialization charging until the battery energy state reaches 100%, and be left alone for more than 12 hours.

3. A battery thermal runaway chain reaction test method according to claim 1, characterized in that: The battery and the heating plate are pre-tightened and clamped by clamping plates, specifically: a plurality of batteries are abutted and arranged between the clamping plates, the inner walls of the clamping plates are provided with heat insulation cotton, and a heating plate is provided on one side of each battery.

4. A battery thermal runaway chain reaction test method according to claim 3, characterized in that: The thermal runaway trigger circuit connected to the battery includes: Install the upper cover plate and fix it directly above the battery, with the spacing distance consistent with the actual battery module / battery cluster structure; The heating plate is connected to the power cable, and the connecting cable is wrapped with fireproof wrap; The heating plate is connected to the power cable, and the connecting cable is wrapped with fireproof wrap; The electric ignition device is fixed above the center of each heating battery, and the cable of the electric ignition device is treated with fireproof coating.

5. A battery thermal runaway chain reaction test method according to claim 1, characterized in that: In the process of connecting the thermal runaway trigger circuit with the data acquisition circuit, the data acquisition circuit is connected with the thermal runaway acquisition device circuit, and the data acquisition device is a voltage, temperature acquisition system and a video acquisition system.

6. A battery thermal runaway chain reaction test method according to claim 1, characterized in that: The battery thermal runaway chain reaction test is to trigger the battery thermal runaway by heating with the aid of electric ignition to carry out a battery module thermal runaway chain reaction test.

7. A battery thermal runaway chain reaction test method according to claim 1, characterized in that: The battery thermal runaway chain reaction test specifically includes: Start the heating plate and continuously observe the temperature and voltage of the heating battery; After the battery safety valve breaks, use a pulse igniter until the smoke is ignited; After the voltage of a certain heating battery drops, turn off the heating plate on the side of the battery away from the spread until the voltage of the last heating battery drops.

8. A battery thermal runaway chain reaction test method according to claim 1, characterized in that: The method of starting the supplementary heating test according to the characteristic parameters of the battery diffusion object includes: Continue to observe the temperature between the supplementary heating plate and the diffusion battery. When the temperature shows a downward trend but the battery has not yet thermally runaway, start the supplementary heating plate to provide heat to the diffusion battery until the voltage drops.

9. A battery thermal runaway chain reaction test method according to claim 1, characterized in that: The method collects data collected in the battery thermal runaway chain reaction test, processes the data, and obtains the heat value required for the battery thermal runaway; including: Record the reheating time, and calculate the heat value ΔH absorbed by the spreading battery and the heat value W required for battery thermal runaway according to the reheating calculation model.

10. A battery thermal runaway chain reaction test method according to claim 9, characterized in that: The heat supplement calculation model includes: ΔH=Mbatteries×Cp×(T-T0) / 1000; W = P·t / 1000*α; In the formula, ΔH is the battery enthalpy change, that is, the absorbed heat; Mbattery is the mass of the battery cell; Cp is the battery specific heat capacity; W is the amount of supplementary heat; P is the power of the supplementary heating plate; t is the supplementary heating time; α is the heat transfer efficiency of the heating plate.

11. A battery thermal runaway chain reaction test method according to claim 1, characterized in that: The safety boundary of the battery thermal runaway chain reaction is obtained by analyzing the heat value absorbed by the propagating battery, the heat value required for the battery thermal runaway, and the threshold value of the number of battery cells that trigger thermal runaway by heating, and then analyzing the safety boundary of the battery thermal runaway chain reaction, including: Obtain the number of heated batteries, the temperature during heating, the heating time, the amount of heat absorbed before heating, the amount of heating, the amount of heat absorbed when thermal runaway is triggered, and whether thermal runaway propagation occurs; Draw the correlation curve between the temperature during heating and the number of heated batteries, the correlation curve between the heat absorbed by the battery before heating and the number of heated batteries, the correlation curve between the heating time and the number of heated batteries, and the correlation curve between the heating amount and the number of heated batteries; The threshold for determining the number of battery cells that need to be heated simultaneously to trigger thermal runaway is obtained by extrapolating the curve, and then the safety boundary of the battery thermal runaway chain reaction is analyzed.

12. A method for determining the safety boundary of a battery thermal runaway chain reaction, characterized in that: include: Obtain the number of heated batteries, the temperature during heating, the heating time, the amount of heat absorbed before heating, the amount of heating, the amount of heat absorbed when thermal runaway is triggered, and whether thermal runaway propagation occurs; Draw the correlation curve between the temperature during heating and the number of heated batteries, the correlation curve between the heat absorbed by the battery before heating and the number of heated batteries, the correlation curve between the heating time and the number of heated batteries, and the correlation curve between the heating amount and the number of heated batteries; The threshold for determining the number of battery cells that need to be heated simultaneously to trigger thermal runaway is obtained by extrapolating the curve, and then the safety boundary of the battery thermal runaway chain reaction is analyzed.

13. The method for determining the safety boundary of battery thermal runaway chain reaction according to claim 12, characterized in that: The heat supplement is calculated based on the heat supplement calculation model to calculate the heat value ΔH absorbed by the propagating battery and the heat value W required for the battery thermal runaway; the heat supplement calculation model includes: ΔH=Mbatteries×Cp×(T-T0) / 1000; W = P·t / 1000*α; In the formula, ΔH is the battery enthalpy change, that is, the absorbed heat; Mbattery is the mass of the battery cell; Cp is the battery specific heat capacity; W is the amount of supplementary heat; P is the power of the supplementary heating plate; t is the supplementary heating time; α is the heat transfer efficiency of the heating plate.

14. A battery thermal runaway chain reaction safety boundary determination system, based on the battery thermal runaway chain reaction safety boundary determination method according to claim 12; characterized in that: include: An acquisition module is used to obtain the number of heated batteries, the temperature during heating, the heating time, the amount of heat absorbed before heating, the amount of heat, the amount of heat absorbed when thermal runaway is triggered, and whether thermal runaway propagation occurs; A drawing module is used to draw a correlation curve between the temperature during heating and the number of heated batteries, a correlation curve between the heat absorbed by the battery before heating and the number of heated batteries, a correlation curve between the heating time and the number of heated batteries, and a correlation curve between the amount of heating heat and the number of heated batteries; The analysis module is used to obtain the threshold value for the number of battery cells that need to be heated simultaneously to trigger thermal runaway through the curve extrapolation method, and then analyze and obtain the safety boundary of the battery thermal runaway chain reaction.

15. An electronic device, characterized in that: It comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method for determining the safety boundary of a battery thermal runaway chain reaction as claimed in claim 12 or 13 when executing the computer program.

16. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for determining the safety boundary of a battery thermal runaway chain reaction according to claim 12 or 13 is implemented.

17. A computer program product, comprising computer instructions, characterized in that: The computer instructions instruct the computer to execute the battery thermal runaway chain reaction safety boundary determination method as described in claim 12 or 13.

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