Battery thermal runaway triggering device, triggering method and triggering system

Abstract

The invention provides a battery thermal runaway triggering device, a triggering method and a triggering system, and relates to the technical field of battery safety testing. The battery thermal runaway triggering device comprises a magnetic field generation module and a triggering monitoring module, the magnetic field generation module is used for continuously applying a high-frequency alternating magnetic field to a target battery in a close range according to the working frequency of the target battery, and the triggering monitoring module is used for monitoring whether the target battery enters a thermal runaway state or not. And under the condition that the target battery enters the thermal runaway state, the magnetic field generation module is controlled to stop working. The battery thermal runaway triggering device can trigger the thermal runaway of the target battery in the shortest time under the condition that excessive energy is not introduced, and the authenticity of the battery thermal spread test process is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of battery safety testing, and in particular to a battery thermal runaway triggering device, a triggering method, and a triggering system. Background Art

[0002] Lithium battery safety testing has become a hot topic in recent years, with thermal runaway testing of lithium-ion batteries being the most critical. During thermal runaway testing, how to trigger thermal runaway in a battery cell is a topic of extensive discussion among researchers and engineers. Currently, the most commonly used methods for triggering thermal runaway in a single cell include: 1. Overcharge, 2. Internal short circuit, 3. Heating, and 4. Needle penetration. Of these, heating offers the most repeatable results, making it the most widely used method for triggering thermal runaway in a single cell.

[0003] However, the existing heating-triggered thermal runaway method introduces more energy into the battery, affecting the authenticity of the battery heat spread test process. Summary of the Invention

[0004] The present invention provides a battery thermal runaway triggering device, triggering method, and triggering system to address the defect in the prior art that the heating-triggered thermal runaway method affects the authenticity of the battery thermal propagation test process. The device can induce thermal runaway of the target battery in the shortest possible time without introducing excessive energy, thereby ensuring the authenticity of the battery thermal propagation test process.

[0005] The present invention provides a battery thermal runaway triggering device, comprising the following modules: A magnetic field generating module, configured to continuously apply a high-frequency alternating magnetic field to the target battery at a close distance according to the operating frequency of the target battery, wherein the operating frequency of the high-frequency alternating magnetic field is greater than or equal to the operating frequency of the target battery, and the high-frequency alternating magnetic field is configured to cause the power density on the surface of the metal layer of the target battery to be greater than or equal to a preset power density threshold, and / or the heating rate to be greater than or equal to a preset heating rate threshold; The trigger monitoring module is used to monitor whether the target battery enters a thermal runaway state, and control the magnetic field generating module to stop working when the target battery enters a thermal runaway state.

[0006] According to a battery thermal runaway triggering device provided by the present invention, the magnetic field generating module includes a high-frequency induction heater and an induction heating coil, wherein: The high-frequency induction heater is configured to continuously output a high-frequency alternating current to the induction heating coil according to the operating frequency of the target battery, wherein the operating frequency corresponding to the high-frequency alternating current is greater than or equal to the operating frequency of the target battery; The induction heating coil is arranged at a target position corresponding to the position to be heated of the target battery, and is used to continuously generate the high-frequency alternating magnetic field to the position to be heated according to the input high-frequency alternating current. The target position is located in a non-contact but close position to the position to be heated.

[0007] According to a battery thermal runaway triggering device provided by the present invention, the high-frequency induction heater includes a frequency determination unit, a power setting unit and a current output unit, wherein: The frequency determination unit is used to determine the operating frequency of the target battery according to the resistivity and relative permeability of the metal layer of the target battery; The power setting unit is used to set the output power of the high-frequency induction heater according to the operating frequency of the target battery; The current output unit is used to continuously output the high-frequency alternating current to the induction heating coil according to the output power.

[0008] According to a battery thermal runaway triggering device provided by the present invention, the frequency determination unit is specifically configured to: Determine the skin depth, which is used to characterize the penetration depth of the high-frequency alternating magnetic field in the target battery, and the value range of the skin depth is 0.1-0.5 mm; The target value is obtained by multiplying the circumference, the vacuum magnetic permeability, the square of the skin depth, and the relative magnetic permeability; The target operating frequency of the battery is obtained by dividing 5 times the resistivity by the target value.

[0009] According to a battery thermal runaway triggering device provided by the present invention, the magnetic field distribution type corresponding to the induction heating coil is a circular magnetic field distribution or a planar spiral magnetic field distribution. If the shape of the target battery is cylindrical, the magnetic field distribution type corresponding to the induction heating coil is the circular magnetic field distribution, and the radial power gradient of the circular magnetic field distribution is ≥2kW / cm³; if the shape of the target battery is square, the magnetic field distribution type corresponding to the induction heating coil is the planar spiral magnetic field distribution, and the magnetic field edge attenuation rate of the planar spiral magnetic field distribution is ≤20% / mm.

[0010] According to a battery thermal runaway triggering device provided by the present invention, the induction heating coil is a water-cooled induction coil, the hollow portion of the water-cooled induction coil is a cooling water circulation passage, and the magnetic field generating module further includes a cooling unit, which is used to provide cooling water circulation for the cooling water circulation passage.

[0011] According to a battery thermal runaway triggering device provided by the present invention, the trigger monitoring module includes a data acquisition unit, a data judgment unit and a trigger control unit, wherein: The data acquisition unit is used to obtain the battery voltage and / or battery surface temperature of the target battery; The data judgment unit is configured to judge whether the battery voltage and / or battery surface temperature of the target battery meet a preset thermal runaway condition, where the preset thermal runaway condition includes a battery voltage sudden drop reaching a preset percentage, and / or a battery surface temperature being greater than or equal to a preset temperature threshold; The trigger control unit is configured to control the magnetic field generating module to stop working when it is determined that the battery voltage and / or the battery surface temperature of the target battery meets the preset thermal runaway condition.

[0012] The present invention also provides a battery thermal runaway triggering method, comprising the following steps: Continuously applying a high-frequency alternating magnetic field to the target battery at a close distance according to the operating frequency of the target battery, wherein the operating frequency of the high-frequency alternating magnetic field is greater than or equal to the operating frequency of the target battery, and the high-frequency alternating magnetic field is used to cause the power density on the surface of the metal layer of the target battery to be greater than or equal to a preset power density threshold, and / or the heating rate to be greater than or equal to a preset heating rate threshold; Monitor whether the target battery enters a thermal runaway state, and stop applying the high-frequency alternating magnetic field to the target battery if the target battery enters a thermal runaway state.

[0013] According to a battery thermal runaway triggering method provided by the present invention, a high-frequency alternating magnetic field is continuously applied to a target battery at a close distance according to the operating frequency of the target battery, comprising: The high-frequency induction heater continuously outputs a high-frequency alternating current to the induction heating coil according to the operating frequency of the target battery, and the operating frequency corresponding to the high-frequency alternating current is greater than or equal to the operating frequency of the target battery; The induction heating coil is set at a target position corresponding to the position to be heated of the target battery, and continuously generates the high-frequency alternating magnetic field to the position to be heated according to the input high-frequency alternating current. The target position is located in a non-contact but close position to the position to be heated.

[0014] The present invention also provides a battery thermal runaway triggering system, comprising a target battery and a battery thermal runaway triggering device as described above.

[0015] The battery thermal runaway trigger device, trigger method, and trigger system provided by the present invention continuously apply a high-frequency alternating magnetic field to the target battery at a close distance according to the operating frequency of the target battery, and utilize the skin effect principle of high-frequency induction heating to produce a rapid heating effect on the surface of the target battery. This can induce thermal runaway of the target battery in the shortest possible time without introducing excessive energy, thereby ensuring the authenticity of the battery heat spread test process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 It is a structural schematic diagram of the battery thermal runaway trigger device provided by the present invention.

[0018] Figure 2 It is a schematic diagram of the installation position of the induction heating coil provided by the present invention.

[0019] Figure 3 This is a principle diagram of the skin effect of high-frequency induction heating provided by the present invention.

[0020] Figure 4 This is the repeatability test result of thermal runaway of cylindrical batteries triggered by high-frequency induction heating provided by the present invention.

[0021] Figure 5 This is the repeatability test result of the thermal runaway of square-shell batteries triggered by high-frequency induction heating provided by the present invention.

[0022] Figure 6 This is the repeatability test result of the thermal runaway of the soft-pack battery triggered by high-frequency induction heating provided by the present invention.

[0023] Figure 7 It is a flow chart of the battery thermal runaway triggering method provided by the present invention. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0025] To alleviate energy shortages and environmental pollution, my country has included the development of new energy vehicles in its strategic emerging technology industries. Currently, the key factor restricting the development of electric vehicles remains lithium-ion batteries. With their high specific energy, long cycle life, and moderate manufacturing costs, lithium-ion batteries are the primary energy source for clean vehicles. However, with the widespread adoption of lithium-ion batteries in cleaner vehicles, safety concerns have inevitably arisen. Due to manufacturing defects or improper use, lithium-ion batteries can experience thermal runaway in extreme situations. Specifically, mechanical abuse (extrusion, puncture, collision, etc.), electrical abuse (overcharge, over-discharge, internal short circuit, etc.), and thermal abuse can cause Joule heat and chemical reaction heat to accumulate within individual cells. This leads to elevated battery temperatures, ultimately triggering a thermal runaway chain reaction that can lead to fires and explosions. Thermal runaway also releases even more heat. Under poor heat dissipation conditions, adjacent cells can be heated from room temperature by the runaway cell, triggering thermal runaway. This process of thermal runaway propagation is known as thermal runaway propagation, also known as thermal runaway diffusion, thermal runaway expansion, or thermal runaway propagation. Once thermal runaway occurs, energy from two or more cells is released into the battery module, significantly increasing the probability of secondary fires in the battery system and potentially posing a threat to the entire module and, ultimately, the vehicle. Therefore, thermal runaway and its spread can easily cause casualties and property damage. Relevant research shows that there is currently no absolutely reliable method to prevent the recurrence of thermal runaway, but its spread can be suppressed at the system level through effective design methods. To prevent such accidents, automakers and battery manufacturers conduct tests on modules to preemptively assess the behavior and hazards of battery thermal runaway spread. This method primarily involves triggering thermal runaway in a single cell, observing its spread throughout the module, and then comprehensively analyzing module safety issues in conjunction with the module's thermal management components.

[0026] Against this backdrop, lithium battery safety testing has become a highly sought-after issue in recent years, with thermal runaway testing of lithium-ion batteries being a particularly critical issue. During thermal runaway testing, the question of how to trigger thermal runaway in a battery is a subject of extensive discussion among researchers and engineers. Ideally, thermal runaway should be induced in the target battery in the shortest possible time without introducing excessive energy, while also minimizing modifications to the target. Currently, commonly used methods for triggering thermal runaway in a cell include: 1. overcharge triggering; 2. internal short circuit triggering; 3. heating triggering; and 4. needle puncture triggering. Current lithium-ion battery thermal runaway triggering technologies have the following major drawbacks: Traditional contact heating methods (such as thin-film heaters) require direct contact with the battery surface, introducing additional heat capacity and an average energy input of 2.4 kJ / Ah, compromising the fidelity of the thermal runaway process. The needle puncture method, due to the randomness of mechanical penetration, has a triggering success rate of less than 80% and cannot precisely control the location of the internal short circuit. The overcharge method is susceptible to interference from the battery management system, resulting in triggering times that fluctuate by more than ±30 seconds. Among the above-mentioned triggering methods, the results of heating triggering are more repeatable, so the heating triggering monomer thermal runaway method is currently the most widely used.

[0027] However, the existing heating-triggered thermal runaway method introduces more energy into the battery, which is also the most criticized shortcoming of heating triggering. The introduction of more energy affects the authenticity of the battery heat spread test process.

[0028] In view of this, an embodiment of the present invention provides a battery thermal runaway triggering device, comprising a magnetic field generating module and a trigger monitoring module. The magnetic field generating module is used to continuously apply a high-frequency alternating magnetic field to a target battery at a close distance according to the operating frequency of the target battery. The operating frequency of the high-frequency alternating magnetic field is greater than or equal to the operating frequency of the target battery. The high-frequency alternating magnetic field is used to make the power density on the surface of the metal layer of the target battery greater than or equal to a preset power density threshold, and / or the heating rate greater than or equal to a preset heating rate threshold. The trigger monitoring module is used to monitor whether the target battery enters a thermal runaway state and, if the target battery enters a thermal runaway state, control the magnetic field generating module to stop working. This device can induce thermal runaway of the target battery in the shortest possible time without introducing excessive energy, thereby ensuring the authenticity of the battery heat spread test process.

[0029] The technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings in the embodiments of the present invention.

[0030] Figure 1 Schematic diagram of the structure of the battery thermal runaway trigger device provided by the present invention. Figure 1 As shown, the battery thermal runaway triggering device 100 includes a magnetic field generating module 101 and a trigger monitoring module 102, wherein: The magnetic field generating module 101 is used to continuously apply a high-frequency alternating magnetic field to the target battery at a close distance according to the operating frequency of the target battery. The operating frequency of the high-frequency alternating magnetic field is greater than or equal to the operating frequency of the target battery. The high-frequency alternating magnetic field is used to make the power density on the surface of the metal layer of the target battery greater than or equal to a preset power density threshold, and / or the heating rate greater than or equal to a preset heating rate threshold.

[0031] It should be noted that the present invention uses a power density control method to implement a layered heating mechanism for the target battery. The preset power density threshold can be 5kW / cm², and the preset heating rate can be 500℃ / s. That is, the surface power density of the target battery metal layer can be focused to ≥5kW / cm² and / or the heating rate can be >500℃ / s. The heat first triggers a chain reaction of exothermic reactions in the second or third electrode layer, and then triggers the overall thermal runaway.

[0032] Among them, there are many ways to continuously apply a high-frequency alternating magnetic field to the target battery at a close distance according to the operating frequency of the target battery. For example, a high-frequency alternating magnetic field can be generated by using the equipment included in the magnetic field generating module, or by using the induction coil included in the magnetic field generating module. The present invention does not limit the structure of the magnetic field generating module.

[0033] The trigger monitoring module 102 is configured to monitor whether the target battery enters a thermal runaway state, and control the magnetic field generating module to stop working if the target battery enters a thermal runaway state.

[0034] It should be noted that there are many ways to use the trigger monitoring module in the present invention to monitor the target battery for thermal runaway, such as using a temperature sensor and an infrared thermal imaging unit to monitor temperature, or using a voltage measuring device to measure voltage, etc. The present invention does not limit the structure of the trigger monitoring module.

[0035] It can be understood that in order to address the problem of excessive energy input in existing thermal runaway triggering methods, the present invention utilizes the skin effect to generate a transient power density of ≥5kW / cm² and / or a heating rate of ≥500℃ / s on the surface of the battery metal layer, thereby achieving directional rapid heating of the shallow layer (2-3 layers) of the electrode.

[0036] The present invention uses the principle of high-frequency electromagnetic induction heating. By generating a high-frequency alternating magnetic field, the high-frequency alternating magnetic field will generate eddy currents on the surface of adjacent metal materials. Eddy currents are also a type of electric current. When flowing through metal materials, they generate heat. Therefore, when the high-frequency alternating magnetic field is close to the lithium-ion battery, a rapid heating effect will be generated on the surface of the lithium battery. Since the heating power can be very large, the thermal runaway of the battery can be triggered in a very short time. Since induction heating is contactless heating, the present invention can induce thermal runaway of the target battery in the shortest possible time without introducing too much energy, thus ensuring the authenticity of the battery heat spread test process.

[0037] The battery thermal runaway trigger device proposed in the present invention can be applied to heat propagation testing in scenarios such as power battery modules and energy storage systems. For example, it can be applied to lithium-ion power battery systems.

[0038] In some embodiments, the magnetic field generating module 101 may include a high-frequency induction heater and an induction heating coil, wherein the high-frequency induction heater is configured to continuously output a high-frequency alternating current to the induction heating coil according to the operating frequency of the target battery.

[0039] It should be noted that the high-frequency induction heater can also be called a frequency adaptive module, which can output 10-500kHz adjustable power with an accuracy of ±0.1%.

[0040] Exemplarily, the high-frequency induction heater can be an alternating current converter that can convert 220V household electricity into high-frequency alternating current. It has a cooling water circulation pipeline inside that can be connected to a water pump and a connecting hose connected to the coil.

[0041] In which, the induction heating coil can be set at a target position corresponding to the position to be heated of the target battery, and is used to continuously generate the high-frequency alternating magnetic field to the position to be heated according to the input high-frequency alternating current, and the target position is located in a non-contact but close position to the position to be heated.

[0042] It should be noted that the induction heating coil can apply a high-frequency alternating magnetic field in a non-contact manner to make the battery surface power density ≥5kW / cm².

[0043] Exemplarily, the induction heating coil may be a water-cooled induction coil, wherein the water-cooled induction coil may be made of pure copper, and the cooling water flow rate is 2-5 L / min.

[0044] The target battery cell's heating location can be determined based on demand. When determining the heating location of a battery cell, the battery module or battery system can first determine which cell to trigger, and then determine the triggering location of the triggered cell. The diameter and size of the induction heating coil can be determined based on the target battery cell's heating location to achieve rapid heating of a specific area. The induction heating coil is then installed at the selected location of the triggered battery cell, i.e., the target location. The target location is located in close proximity to the target location, but not in contact with it.

[0045] Figure 2 Schematic diagram of the installation position of the induction heating coil provided by the present invention. Figure 2 As shown, conventional heating devices can only heat the battery's large surface. The induction heating coil provided by the present invention has extremely high heating power and can achieve rapid heating of the battery at different locations. The present invention can determine heating coils of different diameters based on the size and dimensions of the battery to meet the heating needs of batteries of different sizes. In principle, the smaller the heating area, the higher the heating efficiency.

[0046] It is understandable that the present invention uses a high-frequency induction heating machine to provide a high-frequency alternating current to the induction heating coil, thereby generating a high-frequency alternating magnetic field near the induction heating coil. The high-frequency alternating magnetic field will generate eddy currents on the surface of the adjacent metal material. Eddy currents are also a type of electric current. When flowing through metal materials, they generate heat. Therefore, when the high-frequency induction heating coil is close to the target battery, a rapid heating effect will be generated on the surface of the lithium battery. Since the heating power can be very large, the thermal runaway of the battery will be triggered in a very short time. The present invention uses the skin effect of eddy currents caused by high-frequency induction heating to greatly increase the heating power, thereby achieving the heating of high-thermal-conductivity metals such as copper and aluminum in the battery material, and can achieve efficient triggering of battery thermal runaway.

[0047] In some embodiments, the high-frequency induction heater includes a frequency determination unit, a power setting unit, and a current output unit, wherein the frequency determination unit is used to determine the operating frequency of the target battery based on the resistivity and relative magnetic permeability of the metal layer of the target battery.

[0048] It should be noted that the frequency determination unit can obtain the resistivity ρ and relative permeability μ of the target battery metal layer. r , and then determine the operating frequency of the target battery based on the resistivity and relative magnetic permeability.

[0049] Wherein, the power setting unit is used to set the output power of the high-frequency induction heater according to the operating frequency of the target battery.

[0050] It should be noted that the high-frequency induction heater has an adjustable output power of 10-500kHz, and the corresponding output power can be set according to the operating frequency of the battery to be triggered.

[0051] Wherein, the current output unit is used to continuously output the high-frequency alternating current to the induction heating coil according to the output power.

[0052] It should be noted that after setting the corresponding output power, the high-frequency alternating current can be continuously output to the induction heating coil according to the output power, and the high-frequency alternating current can enable the induction heating coil to generate a high-frequency alternating magnetic field.

[0053] Figure 3 This is a schematic diagram of the skin effect principle of high-frequency induction heating provided by the present invention. Figure 3 As shown, when a large current flows through a conductor, it tends to accumulate on the surface of the conductor, thereby increasing the current density on the conductor surface and, to a certain extent, increasing the heat generated on the conductor surface by 4 times (Q=I 2 Rt). Therefore, for particularly large eddy currents, they will also gather on the surface of the monomer to produce a skin effect, thereby generating a huge heating power, which can achieve rapid heating of the conductor.

[0054] When an alternating current is passed through the induction heating coil of the present invention, an alternating magnetic field with the same frequency variation is excited inside the induction heating coil, and the direction of the magnetic field strength is determined by the right-hand rule. When the magnetic field passes through a nearby conductor, the free electrons inside the conductor are acted upon by the magnetic field force and move, flowing in a plane perpendicular to the magnetic field. Because of their vortex-like shape, they are called eddy currents. The resisting magnetic field generated by eddy currents is always opposite to the change in the external magnetic field, so the eddy currents react to the source of the magnetic field to resist the change. The current flowing through the conductor will dissipate in the form of heat, so induction heating essentially produces a kind of Joule heat. The faster the magnetic field changes, the greater the induced electromotive force, the stronger the eddy current, and the smaller the resistance of the conductor, the greater the heat generated. The essence of eddy current is still electric current. When the current (eddy current) becomes very large, a phenomenon called skin effect will occur.

[0055] Place the induction heating coil close to the target location of the battery cell to be triggered. Since induction heating is a contactless heating method, the heating coil does not need to come into contact with the battery under test. However, since the alternating magnetic field generated by the heating coil decays rapidly with increasing distance, placing the heating coil as close as possible to the battery under test can achieve more efficient heating and thermal runaway triggering. Therefore, the induction heating coil can apply a high-frequency magnetic field with the same operating frequency as f or greater in a non-contact manner, achieving a power density of ≥5kW / cm² on the battery surface, thereby triggering thermal runaway.

[0056] In some embodiments, the frequency determination unit is specifically used to: determine the skin depth, which is used to characterize the penetration depth of the high-frequency alternating magnetic field in the target battery, and the value range of the skin depth is 0.1-0.5 mm; multiply pi, vacuum magnetic permeability, the square of the skin depth, and the relative magnetic permeability to obtain a target value; divide 5 times the resistivity by the target value to obtain the operating frequency of the target battery.

[0057] It should be noted that the present invention adopts a frequency optimization algorithm: according to the resistivity ρ and magnetic permeability μ of the target battery metal layer (positive electrode aluminum foil / negative electrode copper foil) r , calculate the optimal operating frequency f=5ρ / (πμ o μ r δ²), where ρ is the resistivity, μ o is the vacuum permeability, μ r is the relative magnetic permeability, δ is the skin depth, where δ = 0.1-0.5mm, ensuring that effective eddy current is generated within a depth of 0.1-0.5mm.

[0058] It is understandable that the conventional operating frequency (1-10kHz) and heating depth (5-10mm) of existing induction heating technology cannot meet the demand for rapid heating of the shallow surface layer of lithium batteries, that is, the existing technology has not solved the problem of precise matching of power density and heating depth.

[0059] By establishing a mapping relationship between the electromagnetic properties of battery materials and high-frequency parameters, the present invention utilizes the skin effect to generate a transient power density of ≥5kW / cm² within a depth of 0.1-0.5mm in the battery metal layer, achieving directional and rapid heating of the shallow surface layer (2-3 layers) of the electrode, thereby ensuring the authenticity of the battery heat spread test process.

[0060] In some embodiments, the magnetic field distribution type corresponding to the induction heating coil is a circular magnetic field distribution or a planar spiral magnetic field distribution. If the shape of the target battery is cylindrical, the magnetic field distribution type corresponding to the induction heating coil is the circular magnetic field distribution, and the radial power gradient of the circular magnetic field distribution is ≥2kW / cm³. If the shape of the target battery is square, the magnetic field distribution type corresponding to the induction heating coil is the planar spiral magnetic field distribution, and the magnetic field edge attenuation rate of the planar spiral magnetic field distribution is ≤20% / mm.

[0061] As can be understood, the present invention employs a toroidal magnetic field distribution with a radial power gradient of ≥2kW / cm³ for cylindrical batteries, and a planar spiral magnetic field with an edge attenuation of ≤20% / mm for square-shell batteries. This means that the present invention determines the magnetic field distribution type corresponding to the induction heating coil based on the target battery shape, ensuring the effectiveness of the high-frequency alternating magnetic field and improving the accuracy of thermal runaway triggering.

[0062] In some embodiments, the induction heating coil is a water-cooled induction coil, the hollow portion of the water-cooled induction coil is a cooling water circulation passage, and the magnetic field generating module further includes a cooling unit, which is used to provide cooling water circulation for the cooling water circulation passage.

[0063] It should be noted that the induction heating coil can be a water-cooled induction coil. The water-cooled induction coil, that is, a hollow coil, is made of pure copper, has 2 to 4 turns, and the middle hollow part provides a passage for cooling water circulation. The present invention provides cooling water circulation for the cooling water circulation passage through a cooling unit, which can ensure the effect of the high-frequency alternating magnetic field and improve the accuracy of thermal runaway triggering.

[0064] In some embodiments, the trigger monitoring module 102 may include a data acquisition unit, a data judgment unit and a trigger control unit, wherein the data acquisition unit is used to obtain the battery voltage and / or battery surface temperature of the target battery; the data judgment unit is used to judge whether the battery voltage and / or battery surface temperature of the target battery meet the preset thermal runaway conditions, and the preset thermal runaway conditions include the battery voltage suddenly dropping to a preset percentage, and / or the battery surface temperature is greater than or equal to a preset temperature threshold; the trigger control unit is used to control the magnetic field generation module to stop working when it is determined that the battery voltage and / or battery surface temperature of the target battery meet the preset thermal runaway conditions.

[0065] It should be noted that the magnetic field generation module of the present invention can continue heating the battery until the trigger monitoring module detects a voltage sag of 30% or greater or a temperature of 180°C or greater, at which point it controls the magnetic field generation module to cease operation. The trigger monitoring module can include a data acquisition unit, a data judgment unit, and a trigger control unit. These three units work together to monitor whether a preset thermal runaway condition has been met.

[0066] Exemplarily, the data acquisition unit may include an infrared thermal imaging unit having a resolution of 0.5 mm or less and a sampling rate of 100 Hz or more. The infrared thermal imaging unit may acquire the temperature of the target battery, and then determine whether the temperature is greater than or equal to 180°C via the data determination unit. If the temperature is greater than or equal to 180°C, the magnetic field generation module may be deactivated by the trigger control unit, for example, by disconnecting the power supply to the magnetic field generation module.

[0067] It is understandable that the triggering monitoring module can ensure that the high-frequency alternating magnetic field is stopped in time when the target battery enters a thermal runaway state, that is, heating is stopped without adding additional energy, thereby ensuring the authenticity of the battery heat spread test process.

[0068] The following describes an exemplary application of an embodiment of the present invention in a practical application scenario.

[0069] The present invention proposes a battery thermal runaway triggering device, which triggers thermal runaway of a battery system through high-frequency induction heating in the following application scenarios.

[0070] The battery thermal runaway trigger device may include a high-frequency induction heater, a hollow coil, a water pump, and a connecting hose. The high-frequency induction heater can be an alternating current converter, converting 220V household electricity into high-frequency alternating current. It has an internal cooling water circulation pipeline that can connect to the water pump and the connecting hose connected to the coil. The hollow coil is made of pure copper, with 2 to 4 turns, and the hollow portion in the middle provides a path for the cooling water circulation. The connecting pipe is made of a soft material that can provide a path for both cooling water and current while maintaining insulation. The water pump is a conventional submersible pump that provides cooling water for the battery thermal runaway trigger device.

[0071] Applications include using high-frequency induction heating to trigger thermal runaway in different battery types, batteries with different capacities (states of charge), and battery locations. Other applications include triggering thermal runaway in power battery modules, power battery systems, energy storage power station modules, and energy storage battery systems, and verifying whether the tested object can pass thermal diffusion testing.

[0072] The following is an experimental scheme for a high-frequency induction heating triggering method based on a battery thermal runaway triggering device provided by the present invention. The high-frequency induction heating triggering method may include the following steps: S201: Determine the diameter and size of the induction heating coil to achieve rapid heating of a specific area.

[0073] In step S201, heating coils of varying diameters can be used to heat batteries of varying sizes. In principle, the smaller the heating area, the higher the heating efficiency. This method utilizes the skin effect of eddy currents induced by high-frequency induction heating, significantly increasing the heating power. This allows heating of highly conductive metals such as copper and aluminum in battery materials, potentially triggering thermal runaway.

[0074] S202: Determine the heating position of the battery cell. For the battery module or system, first determine which cell to trigger and then determine the triggering position of the triggered cell.

[0075] In step S202 , the traditional heating method can only heat the battery on the large surface of the battery. The present method has extremely high heating power and can achieve rapid heating of the battery at different positions of the battery.

[0076] Figure 4 This is the repeatability test result of the thermal runaway of cylindrical batteries triggered by high-frequency induction heating provided by the present invention. Figure 4As shown, placing the induction heating coil close to the side of a cylindrical battery can quickly trigger thermal runaway. The two images on the right show the test results of two repetitive induction heating triggering attempts. Both heating attempts triggered thermal runaway in the cylindrical battery within 1 second, and both experiments showed good repeatability.

[0077] Figure 5 This is the repeatability test result of the high-frequency induction heating-triggered thermal runaway of square-shell batteries provided by the present invention. Figure 5 As shown, the induction heating coil can trigger thermal runaway on various locations of the prismatic battery, including the large surface (as shown in Figure 5, with a triggering time of less than 10 seconds), the side, and the top. The two images on the right show the test results of two repetitive induction heating triggering attempts. Both heating attempts triggered thermal runaway on the prismatic battery within 10 seconds, and both experiments showed good repeatability.

[0078] Figure 6 This is the repeatability test result of the thermal runaway of soft-pack batteries triggered by high-frequency induction heating provided by the present invention. Figure 6 As shown, the induction heating coil can trigger thermal runaway in different locations of the soft-pack battery, including the large surface, side seals, and bottom seals. The two images on the right show the test results of two repetitive induction heating triggering operations. Both heating operations can trigger thermal runaway of the soft-pack battery within 2 seconds, and both experiments have good repeatability.

[0079] S203: Installing the induction heating coil at the selected position of the battery cell to be triggered.

[0080] In step S203, the induction heating coil is placed close to the selected location of the battery cell to be triggered. Because induction heating is a contactless heating method, the heating coil does not need to come into contact with the battery cell being tested. However, since the alternating magnetic field generated by the heating coil decays rapidly with increasing distance, placing the heating coil as close as possible to the battery cell under test can achieve more efficient heating and thermal runaway triggering. S204: Turn on the cooling system, start the cooling water circulation, supply power to the high-frequency induction heating machine, select the output power, and control the output current; provide cooling water to the induction heating meter and the heating coil, supply power to the high-frequency induction heating machine, and select the output power.

[0081] In step S204, the cooling system is turned on, the cooling water circulation is started, cooling water is provided to the induction heating meter and the heating coil, power is supplied to the high-frequency induction heating machine, and the output power is selected.

[0082] S205: After starting the triggering experiment, confirm that the target cell has thermal runaway and then choose to shut down the power supply of the induction heating machine.

[0083] S206: Collect temperatures at different locations of the battery module and analyze heat spread test data.

[0084] In step S206 , the temperatures at different locations of the battery are collected and the thermal runaway test data is analyzed.

[0085] It is understood that the battery thermal runaway trigger device provided by the present invention calculates the optimal frequency f based on the target battery resistivity ρ and magnetic permeability μ, utilizes a non-contact magnetic field focusing method, and uses a power density closed-loop control method. This method can trigger thermal runaway in <10 seconds with an energy input of less than 1 kJ / Ah, and the trigger time repeatability standard deviation is <0.5 seconds. Experiments have shown that the battery thermal runaway trigger device provided by the present invention has 100% applicability for cylindrical, prismatic, and soft-pack batteries, and a thermal runaway trigger success rate of 98.7%, significantly outperforming traditional heating and acupuncture methods.

[0086] The battery thermal runaway trigger device provided by the present invention has been applied in multiple embodiments, showing excellent repeatability of experimental results, and has the prospect of further application in thermal safety testing of lithium batteries.

[0087] Based on the aforementioned embodiments, an embodiment of the present invention further provides a battery thermal runaway triggering method, which can be applied to a battery thermal runaway triggering system. The battery thermal runaway triggering system can include a battery thermal runaway triggering device and a target battery.

[0088] The battery thermal runaway triggering method provided by the present invention is described below. The battery thermal runaway triggering method described below and the battery thermal runaway triggering device described above can be referenced to each other.

[0089] Figure 7 FIG. 1 is a flow chart of the battery thermal runaway triggering method provided by the present invention. Figure 7 As shown, the battery thermal runaway triggering method may include: Step 301: continuously applying a high-frequency alternating magnetic field to a target battery at a close distance according to the operating frequency of the target battery, wherein the operating frequency of the high-frequency alternating magnetic field is greater than or equal to the operating frequency of the target battery, and the high-frequency alternating magnetic field is used to cause the power density on the surface of the metal layer of the target battery to be greater than or equal to a preset power density threshold, and / or the heating rate to be greater than or equal to a preset heating rate threshold; Step 302: monitoring whether the target battery enters a thermal runaway state, and if the target battery enters a thermal runaway state, stopping applying the high-frequency alternating magnetic field to the target battery.

[0090] In some embodiments, continuously applying a high-frequency alternating magnetic field to the target battery at a close distance according to the operating frequency of the target battery includes: The high-frequency induction heater continuously outputs a high-frequency alternating current to the induction heating coil according to the operating frequency of the target battery, and the operating frequency corresponding to the high-frequency alternating current is greater than or equal to the operating frequency of the target battery; The induction heating coil is set at a target position corresponding to the position to be heated of the target battery, and continuously generates the high-frequency alternating magnetic field to the position to be heated according to the input high-frequency alternating current. The target position is located in a non-contact but close position to the position to be heated.

[0091] In some embodiments, the high-frequency induction heater continuously outputs a high-frequency alternating current to the induction heating coil according to the operating frequency of the target battery, including: determining an operating frequency of the target battery according to the resistivity and relative magnetic permeability of the metal layer of the target battery; Setting the output power of the high-frequency induction heater according to the operating frequency of the target battery; The high-frequency alternating current is continuously output to the induction heating coil according to the output power.

[0092] In some embodiments, determining the operating frequency of the target battery according to the resistivity and relative magnetic permeability of the metal layer of the target battery includes: Determine the skin depth, where the skin depth is used to characterize the penetration depth of the high-frequency alternating magnetic field in the target battery, and the skin depth may be in the range of 0.1-0.5 mm; The target value is obtained by multiplying the circumference, the vacuum magnetic permeability, the square of the skin depth, and the relative magnetic permeability; The target operating frequency of the battery is obtained by dividing 5 times the resistivity by the target value.

[0093] In some embodiments, the magnetic field distribution type corresponding to the induction heating coil is a circular magnetic field distribution or a planar spiral magnetic field distribution. If the shape of the target battery is cylindrical, the magnetic field distribution type corresponding to the induction heating coil is the circular magnetic field distribution, and the radial power gradient of the circular magnetic field distribution is ≥2kW / cm³. If the shape of the target battery is square, the magnetic field distribution type corresponding to the induction heating coil is the planar spiral magnetic field distribution, and the magnetic field edge attenuation rate of the planar spiral magnetic field distribution is ≤20% / mm.

[0094] In some embodiments, the induction heating coil is a water-cooled induction coil, the hollow portion of the water-cooled induction coil is a cooling water circulation passage, and the magnetic field generating module further includes a cooling unit, which is used to provide cooling water circulation for the cooling water circulation passage.

[0095] In some embodiments, monitoring whether the target battery enters a thermal runaway state, and stopping applying the high-frequency alternating magnetic field to the target battery when the target battery enters a thermal runaway state, includes: Acquiring a battery voltage and / or a battery surface temperature of the target battery; Determining whether the battery voltage and / or battery surface temperature of the target battery meet a preset thermal runaway condition, where the preset thermal runaway condition includes a battery voltage sudden drop reaching a preset percentage and / or a battery surface temperature being greater than or equal to a preset temperature threshold; When it is determined that the battery voltage and / or the battery surface temperature of the target battery meets the preset thermal runaway condition, the application of the high-frequency alternating magnetic field to the target battery is stopped.

[0096] In the embodiment of the present invention, thermal runaway of the target battery can be induced in the shortest possible time without introducing excessive energy, thereby ensuring the authenticity of the battery heat spread test process.

[0097] On the other hand, the present invention also provides a battery thermal runaway triggering system, including a target battery and a battery thermal runaway triggering device provided by the above-mentioned devices.

[0098] The device / system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network elements. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present embodiment without inventive effort.

[0099] Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a necessary general-purpose hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (such as a personal computer, server, or network device) to execute the methods described in each embodiment or certain portions of the embodiments.

[0100] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A battery thermal runaway triggering device, characterized in that: include: A magnetic field generating module, configured to continuously apply a high-frequency alternating magnetic field to the target battery at a close distance according to the operating frequency of the target battery, wherein the operating frequency of the high-frequency alternating magnetic field is greater than or equal to the operating frequency of the target battery, and the high-frequency alternating magnetic field is configured to cause the power density on the surface of the metal layer of the target battery to be greater than or equal to a preset power density threshold, and / or the heating rate to be greater than or equal to a preset heating rate threshold; The trigger monitoring module is used to monitor whether the target battery enters a thermal runaway state, and control the magnetic field generating module to stop working when the target battery enters a thermal runaway state.

2. The battery thermal runaway triggering device according to claim 1, characterized in that: The magnetic field generating module includes a high-frequency induction heater and an induction heating coil, wherein: The high-frequency induction heater is configured to continuously output a high-frequency alternating current to the induction heating coil according to the operating frequency of the target battery, wherein the operating frequency corresponding to the high-frequency alternating current is greater than or equal to the operating frequency of the target battery; The induction heating coil is arranged at a target position corresponding to the position to be heated of the target battery, and is used to continuously generate the high-frequency alternating magnetic field to the position to be heated according to the input high-frequency alternating current. The target position is located in a non-contact but close position to the position to be heated.

3. The battery thermal runaway triggering device according to claim 2, characterized in that: The high-frequency induction heater includes a frequency determination unit, a power setting unit and a current output unit, wherein: The frequency determination unit is used to determine the operating frequency of the target battery according to the resistivity and relative permeability of the metal layer of the target battery; The power setting unit is used to set the output power of the high-frequency induction heater according to the operating frequency of the target battery; The current output unit is used to continuously output the high-frequency alternating current to the induction heating coil according to the output power.

4. The battery thermal runaway triggering device according to claim 3, characterized in that: The frequency determination unit is specifically configured to: Determine the skin depth, which is used to characterize the penetration depth of the high-frequency alternating magnetic field in the target battery, and the value range of the skin depth is 0.1-0.5 mm; The target value is obtained by multiplying the circumference, the vacuum magnetic permeability, the square of the skin depth, and the relative magnetic permeability; The target operating frequency of the battery is obtained by dividing 5 times the resistivity by the target value.

5. The battery thermal runaway triggering device according to claim 2, characterized in that: The magnetic field distribution type corresponding to the induction heating coil is an annular magnetic field distribution or a planar spiral magnetic field distribution. If the shape of the target battery is cylindrical, the magnetic field distribution type corresponding to the induction heating coil is the annular magnetic field distribution, and the radial power gradient of the annular magnetic field distribution is ≥2kW / cm³. If the shape of the target battery is square, the magnetic field distribution type corresponding to the induction heating coil is the planar spiral magnetic field distribution, and the magnetic field edge attenuation rate of the planar spiral magnetic field distribution is ≤20% / mm.

6. The battery thermal runaway triggering device according to claim 2, characterized in that: The induction heating coil is a water-cooled induction coil, the hollow portion of the water-cooled induction coil is a cooling water circulation passage, and the magnetic field generating module further comprises a cooling unit, which is used to provide cooling water circulation for the cooling water circulation passage.

7. The battery thermal runaway triggering device according to claim 1, characterized in that: The trigger monitoring module includes a data acquisition unit, a data judgment unit and a trigger control unit, wherein: The data acquisition unit is used to obtain the battery voltage and / or battery surface temperature of the target battery; The data judgment unit is configured to judge whether the battery voltage and / or battery surface temperature of the target battery meet a preset thermal runaway condition, where the preset thermal runaway condition includes a battery voltage sudden drop reaching a preset percentage, and / or a battery surface temperature being greater than or equal to a preset temperature threshold; The trigger control unit is configured to control the magnetic field generating module to stop working when it is determined that the battery voltage and / or the battery surface temperature of the target battery meets the preset thermal runaway condition.

8. A battery thermal runaway triggering method, characterized in that: include: Continuously applying a high-frequency alternating magnetic field to the target battery at a close distance according to the operating frequency of the target battery, wherein the operating frequency of the high-frequency alternating magnetic field is greater than or equal to the operating frequency of the target battery, and the high-frequency alternating magnetic field is used to cause the power density on the surface of the metal layer of the target battery to be greater than or equal to a preset power density threshold, and / or the heating rate to be greater than or equal to a preset heating rate threshold; Monitor whether the target battery enters a thermal runaway state, and stop applying the high-frequency alternating magnetic field to the target battery if the target battery enters a thermal runaway state.

9. The battery thermal runaway triggering method according to claim 8, characterized in that: The step of continuously applying a high-frequency alternating magnetic field to the target battery at a close distance according to the operating frequency of the target battery includes: The high-frequency induction heater continuously outputs a high-frequency alternating current to the induction heating coil according to the operating frequency of the target battery, and the operating frequency corresponding to the high-frequency alternating current is greater than or equal to the operating frequency of the target battery; The induction heating coil is set at a target position corresponding to the position to be heated of the target battery, and continuously generates the high-frequency alternating magnetic field to the position to be heated according to the input high-frequency alternating current. The target position is located in a non-contact but close position to the position to be heated.

10. A battery thermal runaway triggering system, comprising a target battery, characterized in that: It also includes the battery thermal runaway triggering device according to any one of claims 1 to 7.

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