Battery thermal runaway internal termination method and system based on acoustic cavitation effect

Abstract

The invention discloses a battery thermal runaway internal termination method and system based on an acoustic cavitation effect, and the method comprises the steps: obtaining a thermal runaway early warning signal of a new energy battery containing a liquid electrolyte, and enabling a battery management system to recognize the early warning signal through a multi-parameter sensor of the battery; high-intensity ultrasonic waves are applied to the battery, so that the high-intensity ultrasonic waves penetrate through the battery shell and spread in the internal liquid electrolyte; the method comprises the following steps: exciting an acoustic cavitation effect in a liquid electrolyte by using high-strength ultrasonic waves, generating micron-sized microbubbles by the acoustic cavitation effect, violently collapsing the microbubbles under a positive pressure phase of the acoustic waves, and generating high temperature not lower than 5000K and high pressure not lower than 1000atm; liquid electrolyte molecules are subjected to pyrolysis, supercritical oxidation or mechanical cracking through high temperature and high pressure, so that the chemical structure is irreversibly damaged, and the ionic conductivity is lost; and judging that the liquid electrolyte is invalid and terminating the thermal runaway of the battery. According to the invention, the reaction medium is destroyed from the interior of the battery, fundamental termination is realized, the response is extremely rapid, and secondary pollution is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy battery safety technology, in particular to a battery thermal runaway internal termination method and system based on acoustic cavitation effect. BACKGROUND

[0002] Current battery thermal runaway prevention and control technologies all have inherent limitations. Chemical extinguishing agents are difficult to penetrate the interior and may reignite. Phase change materials have limited heat absorption capacity. Built-in chemicals pose compatibility and safety risks. The above solutions all belong to the category of "external intervention" or "passive response".

[0003] For example, Chinese invention patent application No. CN109655748 A discloses a method for determining the thermal runaway temperature performance of a lithium ion battery, a method for evaluating the thermal runaway performance of a lithium ion battery, and a method for evaluating a thermal management system. The method for determining the thermal runaway temperature performance of a lithium ion battery involves heating a test battery to a predetermined heating temperature and detecting the temperature change of the test battery after stopping heating. Further, by determining whether the temperature of the test battery continues to rise, the numerical range of the thermal runaway temperature of the lithium ion battery is determined. The evaluation method for the thermal runaway performance of the lithium ion battery provided by the application can accurately determine the numerical value of the thermal runaway temperature of the lithium ion battery under the actual working state of the lithium ion battery.

[0004] For another example, Chinese invention patent application No. CN118313468 A discloses a battery thermal runaway risk analysis method and device, electronic equipment and storage medium, relating to the field of battery technology. The specific implementation scheme is as follows: analyze the multiple background factor information of each expert among at least one expert, determine the comprehensive weight of each expert according to the analysis results of the multiple background factor information; obtain at least one first language variable of each expert; determine the first fuzzy number of each battery thermal runaway problem according to the at least one first language variable and the comprehensive weight of each expert; determine the prior probability of each battery thermal runaway problem according to the first fuzzy number of each battery thermal runaway problem; determine the prior probability of each root node in the battery thermal runaway dynamic Bayesian network model according to the mapping relationship between each battery thermal runaway problem and the root nodes in the pre-established battery thermal runaway dynamic Bayesian network model.

[0005] The existing technology involves external intervention, cannot touch the internal core, passive response, lags behind the thermal runaway process, chemical addition / interior modification, poor compatibility, and based on the above technical problems existing in the prior art, the present application provides a battery thermal runaway internal termination method and system based on acoustic cavitation effect. SUMMARY

[0006] To address the aforementioned technical problems in the existing technology, this invention provides a method and system for internal termination of battery thermal runaway based on acoustic cavitation effect.

[0007] The present invention adopts the following technical solution:

[0008] This invention provides a method for internal termination of battery thermal runaway based on acoustic cavitation effect, comprising:

[0009] Step 1: Obtain the thermal runaway early warning signal of the new energy battery containing liquid electrolyte. The early warning signal is identified by the battery management system through the battery's multi-parameter sensors.

[0010] Step 2: Apply high-intensity ultrasound to the battery so that the high-intensity ultrasound can penetrate the battery casing and propagate in the internal liquid electrolyte.

[0011] Step 3: High-intensity ultrasound is used to excite acoustic cavitation effect in liquid electrolyte. Acoustic cavitation effect generates micron-sized microbubbles. The microbubbles collapse violently under the positive pressure phase of the acoustic wave and generate a high temperature of not less than 5000K and a high pressure of not less than 1000atm.

[0012] Step 4: The liquid electrolyte molecules are subjected to pyrolysis, supercritical oxidation, or mechanical pyrolysis under high temperature and high pressure, causing irreversible destruction of their chemical structure and loss of ionic conductivity.

[0013] Step 5: Determine if the liquid electrolyte has failed and terminate the battery thermal runaway.

[0014] Furthermore, in step 2, the frequency range of the high-intensity ultrasound is from 500 kHz to 1.5 MHz.

[0015] Furthermore, in step 2, the high-intensity ultrasound operates in a high-frequency pulse mode, with a pulse width of 1 μs to 100 μs, a pulse repetition frequency of 10 Hz to 1 kHz, and an ultrasonic intensity of not less than 10 W / cm². 2 Peak sound intensity is 10 W / cm 2 Up to 1000W / cm 2 .

[0016] Furthermore, in step 2, high-intensity ultrasonic waves are applied through a high-power ultrasonic transducer array. The high-power ultrasonic transducer array is tightly attached to the battery casing, and an acoustic coupling layer is provided between the two. The acoustic coupling layer is a silicone pad, a polyurethane-based flexible coupling pad, or a high-viscosity liquid ultrasonic coupling agent. If it is a liquid coupling agent, it is injected through a microchannel pre-set at the edge of the transducer array.

[0017] Furthermore, step 2 also includes a beam localization and focusing step:

[0018] A low-power sweep frequency signal of 20kHz to 100kHz is emitted by a high-power ultrasonic transducer array. Combined with the echo signal or battery surface temperature data, the thermal runaway initiation area is located with a positioning accuracy of not less than millimeters. Then, the phase difference of the emitted signal of each unit of the transducer array is adjusted so that the sound beam is focused on the initiation area. After focusing, the focal size of the sound beam is not greater than 1 / 2 of the wavelength of the ultrasonic wave in the acoustic coupling layer.

[0019] Furthermore, the criteria for determining the failure of the liquid electrolyte in step 5 include:

[0020] The ionic conductivity of the liquid electrolyte drops to 10. -4 S / cm or less; the battery temperature rise rate decreases from >1℃ / s to <0.1℃ / s or shows a negative slope; the battery voltage fluctuation amplitude is <10mV / s; the pressure rise rate monitored by the pressure sensor is <0.1kPa / s; the battery impedance modulus increases by more than 50% from the initial value in the frequency range of 1kHz to 100Hz; the CO2 or C2H4 concentration rise rate decreases to zero; all battery types can use multi-parameter fusion decision, that is, at least two of the three parameters of temperature, voltage and impedance reach the threshold, which is considered as successful termination.

[0021] The present invention also provides an internal termination system for battery thermal runaway based on acoustic cavitation effect, comprising:

[0022] A high-power ultrasonic transducer array, composed of multiple piezoelectric ceramic transducer units, is used to emit high-intensity ultrasonic waves into new energy batteries containing liquid electrolyte. The high-intensity ultrasonic waves can penetrate the battery shell and excite acoustic cavitation effect in the liquid electrolyte.

[0023] A high-frequency power amplifier, electrically connected to a high-power ultrasonic transducer array, provides kW-level peak output power to drive the transducer array to generate ultrasonic intensity of not less than 10 W / cm². 2 High-intensity ultrasound;

[0024] The intelligent control unit is electrically connected to the high-frequency power amplifier and the battery management system, respectively, and is used to receive the thermal runaway early warning signal of the battery management system and control the timing, frequency, power and duration of ultrasonic wave transmission.

[0025] A matching layer and coupling agent are placed between the high-power ultrasonic transducer array and the battery casing to reduce the reflection loss of sound waves at the medium interface; the system terminates the battery thermal runaway by causing the liquid electrolyte to fail through acoustic cavitation effect.

[0026] Furthermore, the bonding structure between the high-power ultrasonic transducer array and the battery casing includes:

[0027] The spring-loaded flat-plate bonding structure includes a flat transducer module and a pressure plate frame with a compression spring. The pressure plate frame is fixed to the battery module by bolts or quick-lock buckles, and the compression spring provides a contact pressure of 0.1MPa to 0.3MPa.

[0028] The adaptive clamping structure includes a flat transducer module and a C-shaped / O-shaped rigid clamp. The clamp applies uniform pressure to the battery module through straps, screws or hydraulic locking devices.

[0029] Embedded flexible bonding structures include PVDF piezoelectric film arrays, PZT ceramic composite flexible arrays, or transducer arrays bonded to the inside of the battery module cooling plate / side plate via epoxy resin.

[0030] Furthermore, it also includes a heat dissipation module:

[0031] The heat dissipation module includes a microchannel liquid cooling plate integrated into the mounting substrate of the high-power ultrasonic transducer array, and the liquid cooling plate is connected in series or in parallel with the battery module liquid cooling system.

[0032] A thermally conductive silicone grease or a phase change thermal pad is provided between the high-power ultrasonic transducer array and the mounting substrate.

[0033] The intelligent control unit can monitor the temperature of the transducer array and usually reduces the transmission power or suspends operation for protection when the temperature exceeds 80°C; however, in thermal runaway intervention mode, the control unit will prioritize the execution of the termination task.

[0034] Furthermore, the center-to-center spacing d of each transducer unit in the high-power ultrasonic transducer array satisfies d≤λ / 2, where λ is the wavelength of the ultrasonic wave in the acoustic coupling layer;

[0035] When the ultrasonic frequency is 1MHz, the spacing d is 0.5mm to 2.0mm.

[0036] Compared with the prior art, the superior effects of the present invention are as follows:

[0037] 1. The battery thermal runaway internal termination method based on acoustic cavitation effect described in this invention uses ultrasound to excite cavitation within the electrolyte, generating a high temperature of 5000K and a high voltage of 1000 atm, causing the electrolyte molecules to undergo pyrolysis, supercritical oxidation, or mechanical pyrolysis, reducing the ionic conductivity to 10. -4 Below S / cm, it completely loses its ion transport capability;

[0038] 2. The battery thermal runaway internal termination method based on acoustic cavitation effect described in this invention allows the battery management system (BMS) to immediately initiate ultrasonic wave emission upon detecting thermal runaway. In contrast, traditional phase change materials require several seconds to tens of seconds to reach their heat absorption peak and rely on temperature conduction, which cannot match the explosive heat generation in the initial stage of thermal runaway. The ultrasonic wave propagation speed is the speed of sound in the medium, and the cavitation bubble collapse process is completed in nanoseconds to microseconds. Experimental data shows that this invention can cause the electrolyte to fail within 500ms after thermal runaway is triggered, while traditional chemical fire extinguishing agents require 3-5 seconds to penetrate into the battery.

[0039] 3. The battery thermal runaway internal termination method based on acoustic cavitation effect described in this invention uses an external transducer array bonded to the module shell, eliminating the need to add sensors, reagent storage, or other structures inside the battery. This avoids the energy density reduction and compatibility risks caused by existing invasive technologies.

[0040] 4. The battery thermal runaway internal termination method based on acoustic cavitation effect described in this invention achieves millimeter-level positioning accuracy by combining low-power frequency sweep signals with echo or infrared data; phased array technology achieves real-time scanning and dynamic focusing of the acoustic beam by adjusting the phase difference of the transducer units.

[0041] 5. The battery thermal runaway internal termination method based on acoustic cavitation effect described in this invention uses cavitation effect decomposition products such as CO2, C2H4, and LiF, which are inherent components of the electrolyte, without adding any new contaminants;

[0042] 6. The battery thermal runaway internal termination method based on acoustic cavitation effect described in this invention supports frequency extension above 2MHz, can further improve focusing accuracy, and has a focal point size of <0.5mm, which meets the micro-nano-level thermal runaway control requirements of future solid-state batteries. Attached Figure Description

[0043] Figure 1 This is a schematic diagram illustrating the principle of acoustic cavitation effect in an embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram illustrating the working principle of the battery thermal runaway internal termination method based on acoustic cavitation effect as described in this embodiment of the invention.

[0045] Figure 3 This is a schematic diagram of the experimental apparatus of Embodiment 1 of the present invention;

[0046] Figure 4 This is a conceptual diagram of a hoop-type ultrasonic transducer array applied to a cylindrical battery module in an embodiment of the present invention;

[0047] Figure label:

[0048] 1. Water tank; 2. Beaker; 3. Ultrasonic amplitude transformer probe; 4. Ultrasonic generator; 5. Electrolyte; 6. Bubble; 7. Battery module shell; 8. Cylindrical battery cell; 9. Hoop; 10. Hoop inner wall; 11. Transducer unit; 12. Coolant flow channel. Detailed Implementation

[0049] To better understand the above-mentioned objectives, features and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0050] Example

[0051] like Figure 1 As shown, the battery thermal runaway internal termination method based on acoustic cavitation effect includes:

[0052] Step 1: Obtain the thermal runaway early warning signal of the new energy battery containing liquid electrolyte. The early warning signal is identified by the battery management system through the battery's multi-parameter sensors.

[0053] Step 2: Apply high-intensity ultrasound to the battery so that the high-intensity ultrasound can penetrate the battery casing and propagate in the internal liquid electrolyte.

[0054] Step 3: High-intensity ultrasound is used to excite acoustic cavitation effect in liquid electrolyte. Acoustic cavitation effect generates micron-sized microbubbles. The microbubbles collapse violently under the positive pressure phase of the acoustic wave and generate a high temperature of not less than 5000K and a high pressure of not less than 1000atm.

[0055] Step 4: The liquid electrolyte molecules are subjected to pyrolysis, supercritical oxidation, or mechanical pyrolysis under high temperature and high pressure, causing irreversible destruction of their chemical structure and loss of ionic conductivity.

[0056] Step 5: Determine if the liquid electrolyte has failed and terminate the battery thermal runaway.

[0057] Specifically, this invention applies high-intensity ultrasonic waves of a specific frequency and power to the battery body from the outside of the battery. These sound waves penetrate the battery casing and propagate in the electrolyte inside, generating and destroying microbubbles through acoustic cavitation. The instantaneous collapse of the microbubbles generates extreme high temperatures, high pressures, and shock waves locally. These extreme conditions are sufficient to cause the surrounding electrolyte molecules to undergo pyrolysis, supercritical oxidation, or mechanical pyrolysis, resulting in irreversible destruction of their chemical structure, instantaneous loss of ionic conductivity, and ultimately eradication of the electrochemical basis of thermal runaway.

[0058] Furthermore, in step 2, the frequency range of the high-intensity ultrasound is from 500 kHz to 1.5 MHz.

[0059] Specifically, the ultrasonic frequency range is preferably 200kHz to 2MHz, and particularly preferably 500kHz to 1.5MHz, in order to balance the sound wave penetration capability and cavitation generation efficiency.

[0060] Frequency selection criteria:

[0061] Limitations of the low-frequency band (20kHz-100kHz):

[0062] Advantages: Low cavitation threshold, easy to generate cavitation, high cavitation bubble energy, and strong destructive force;

[0063] Fatal flaws: poor penetration ability, long wavelength, and difficulty in focusing. In a multi-layered medium such as a battery module, including the casing, electrodes, and separator, low-frequency sound waves attenuate extremely quickly, and most of the energy is reflected or absorbed by the casing, making it impossible to effectively transfer to the internal electrolyte. At the same time, the long wavelength makes it impossible to achieve precise "targeted" focusing, which may affect normal battery cells.

[0064] 20-100kHz may not be suitable for battery thermal runaway termination scenarios that require penetration of the casing and precise intervention inside; it is more suitable for liquid handling in open containers.

[0065] Applicability in the high-frequency band of 500kHz-2MHz:

[0066] Advantages: Shorter wavelength, stronger penetration, easier electron focusing and scanning, phased array technology, which ensures that energy enters the battery more effectively and acts precisely on the thermal runaway initiation point, avoiding accidental damage;

[0067] Challenge: The cavitation threshold increases with frequency, requiring higher acoustic intensity to trigger cavitation;

[0068] Conclusion: For packaged batteries, especially those with metal casings (steel or aluminum), 500kHz to 2MHz is a more realistic and effective frequency selection range. Among them, around 1MHz is an ideal compromise, balancing sufficient penetration and an achievable cavitation threshold.

[0069] Furthermore, in step 2, the high-intensity ultrasound operates in a high-frequency pulse mode, with a pulse width of 1 μs to 100 μs, a pulse repetition frequency of 10 Hz to 1 kHz, and an ultrasonic intensity of not less than 10 W / cm². 2 Peak sound intensity is 10 W / cm 2 Up to 1000W / cm 2 .

[0070] Specifically, the ultrasonic working mode is high-frequency pulsed, and its peak sound intensity needs to be sufficient to excite cavitation in the electrolyte inside the battery, typically ranging from 10 to 1000 W / cm². 2The pulse width is adjustable within a certain range, and the specific parameters are dynamically optimized by the intelligent control unit according to the battery type, casing thickness and thermal runaway stage. The pulse width is 1-100μs and the pulse repetition frequency is 10Hz-1kHz.

[0071] Furthermore, in step 2, high-intensity ultrasonic waves are applied through a high-power ultrasonic transducer array. The high-power ultrasonic transducer array is tightly attached to the battery casing, and an acoustic coupling layer is provided between the two. The acoustic coupling layer is a silicone pad, a polyurethane-based flexible coupling pad, or a high-viscosity liquid ultrasonic coupling agent. If it is a liquid coupling agent, it is injected through a microchannel pre-set at the edge of the transducer array.

[0072] Furthermore, step 2 also includes a beam localization and focusing step:

[0073] A low-power sweep frequency signal of 20kHz to 100kHz is emitted by a high-power ultrasonic transducer array. Combined with the echo signal or battery surface temperature data, the thermal runaway initiation area is located with a positioning accuracy of not less than millimeters. Then, the phase difference of the emitted signal of each unit of the transducer array is adjusted so that the sound beam is focused on the initiation area. After focusing, the focal size of the sound beam is not greater than 1 / 2 of the wavelength of the ultrasonic wave in the acoustic coupling layer.

[0074] Furthermore, the criteria for determining the failure of the liquid electrolyte in step 5 include:

[0075] The ionic conductivity of the liquid electrolyte drops to 10. -4 S / cm or less; the battery temperature rise rate decreases from >1℃ / s to <0.1℃ / s or shows a negative slope; the battery voltage fluctuation amplitude is <10mV / s; in the frequency range of 1kHz to 100Hz, the battery impedance modulus increases by more than 50% compared to the initial value.

[0076] Specifically, the ionic conductivity decreased to 10. -4 When the S / cm ratio is below a certain level, the electrolyte essentially loses its ion conduction capacity and can be considered to have failed.

[0077] Criteria for determining the termination of thermal runaway under different battery types:

[0078] The criteria for judging 18650 cylindrical batteries include:

[0079] The temperature slope changes as follows: during thermal runaway, the rate of temperature rise is >1℃ / s, and after termination, it should drop to <0.1℃ / s or show a negative slope.

[0080] The voltage is stable, and stops changing after a sudden drop, with fluctuations of <10mV / s;

[0081] The internal pressure, monitored by a pressure sensor, shows a slowing rate of increase of <0.1 kPa / s.

[0082] Square lithium iron phosphate batteries have similar evaluation criteria, but it should be noted that they have a larger heat capacity and may experience slower temperature changes. Therefore, the following can be added:

[0083] In the impedance spectrum (EIS), an increase of more than 50% in the impedance modulus within the range of 1 kHz–100 Hz indicates impeded ion transport.

[0084] Gas sensor, the rate of increase of CO2 or C2H4 concentration drops to zero;

[0085] For general indicators, all battery types can use multi-parameter fusion judgment, that is, at least two of the three parameters of temperature, voltage and impedance reach the threshold. For example, if the temperature is <60℃ and the impedance is >200% of the initial value, it is considered to be a successful termination.

[0086] like Figure 2 As shown, the present invention also provides an internal termination system for battery thermal runaway based on acoustic cavitation effect, comprising:

[0087] A high-power ultrasonic transducer array, composed of multiple piezoelectric ceramic transducer units, is used to emit high-intensity ultrasonic waves into new energy batteries containing liquid electrolyte. The high-intensity ultrasonic waves can penetrate the battery shell and excite acoustic cavitation effect in the liquid electrolyte.

[0088] A high-frequency power amplifier, electrically connected to a high-power ultrasonic transducer array, provides kW-level peak output power to drive the transducer array to generate ultrasonic intensity of not less than 10 W / cm². 2 High-intensity ultrasound;

[0089] The intelligent control unit is electrically connected to the high-frequency power amplifier and the battery management system, respectively, and is used to receive the thermal runaway early warning signal of the battery management system and control the timing, frequency, power and duration of ultrasonic wave transmission.

[0090] A matching layer and coupling agent are placed between the high-power ultrasonic transducer array and the battery casing to reduce the reflection loss of sound waves at the medium interface; the system terminates the battery thermal runaway by causing the liquid electrolyte to fail through acoustic cavitation effect.

[0091] Specifically, the total power of the system in kW should be calculated by back-calculation based on the total area of ​​the transducer array and the required acoustic intensity. To effectively excite cavitation, the ultrasonic power density needs to reach 10 W / cm². 2 above.

[0092] Positioning and focusing techniques:

[0093] Phased array technology allows ultrasonic transducer arrays to be designed as phased arrays. The intelligent control unit adjusts the phase difference of the emitted signals of each unit and realizes electronic focusing and scanning of the sound beam based on beamforming algorithms.

[0094] During the positioning phase, a low-power frequency sweep signal is transmitted, such as a 20–100kHz scan. Hot spots are located by receiving echoes (time reversal method) or battery surface temperature distribution (infrared assistance). The positioning accuracy can reach the millimeter level.

[0095] During the focusing phase, after calculating the focal coordinates, the phase is adjusted to focus the sound beam onto the target area. The focal size can be controlled within λ / 2 (λ is the wavelength, approximately 0.75 mm at 1 MHz).

[0096] Feedback mechanism:

[0097] To determine if the ultrasound is effective, adjust the parameters based on the following real-time feedback after the ultrasound has been applied:

[0098] Impedance spectrum monitoring involves injecting a small-amplitude AC signal (1–100 kHz) during the interval between ultrasonic pulses to measure the battery impedance. If the impedance modulus increases by more than 50% within 1 minute, it indicates that the electrolyte has been successfully decomposed.

[0099] Temperature feedback is achieved by monitoring the battery surface temperature through a built-in thermocouple or infrared thermal imager. If the rate of temperature rise decreases by more than 90%, it is considered effective.

[0100] Acoustic feedback uses a transducer array that also acts as a receiver to monitor changes in the sound wave transmission / reflection coefficient. An increase in acoustic impedance indicates a change in the internal medium.

[0101] The control logic inputs feedback signals to the intelligent control unit. If the input is deemed invalid (e.g., the temperature continues to rise), the ultrasonic parameters are adjusted (e.g., the power is increased to 120% or the frequency is switched). If the input is valid, the transmission is stopped and the system enters monitoring mode.

[0102] Furthermore, the bonding structure between the high-power ultrasonic transducer array and the battery casing includes:

[0103] The spring-loaded flat-plate bonding structure includes a flat transducer module and a pressure plate frame with a compression spring. The pressure plate frame is fixed to the battery module by bolts or quick-lock buckles, and the compression spring provides a contact pressure of 0.1MPa to 0.3MPa.

[0104] The adaptive clamping structure includes a flat transducer module and a C-shaped / O-shaped rigid clamp. The clamp applies uniform pressure to the battery module through straps, screws or hydraulic locking devices.

[0105] Embedded flexible bonding structures include PVDF piezoelectric film arrays, PZT ceramic composite flexible arrays, or transducer arrays bonded to the inside of the battery module cooling plate / side plate via epoxy resin.

[0106] Specifically, the design is to fit closely to the outer surface of the battery module. It is the battery module, not the battery itself. Most modules on the market are square, including square, cylindrical (18650, 21700), and pouch batteries of different specifications.

[0107] For square battery modules, a spring-loaded plate-type planar bonding structure is used.

[0108] Detailed structure and working mechanism:

[0109] The transducer array is manufactured as a standard-sized flat panel module, the area of ​​which can cover most of one side of the module;

[0110] In terms of installation, the module is not directly fixed to the assembly; instead, it is pressed against the side wall of the assembly by a pressure plate frame with multiple compression springs.

[0111] Fitting mechanism:

[0112] Align the transducer module with the pre-coated solid coupling pad or the pre-reserved coupling agent injection port with the planar sidewall of the module.

[0113] Secure the entire pressure plate frame to the module mounting points using bolts or quick-lock clips, such as the screw holes or slots on the module frame.

[0114] When the bolts are tightened, the pressure plate compresses the spring, generating a uniform and quantifiable contact pressure to ensure that there are no air bubbles or gaps between the coupling layer and the module housing. The spring structure can automatically compensate for the dimensional tolerances between different modules and mounting base plates.

[0115] Coupling agent management:

[0116] The preferred solution is a solid coupling pad, in which a layer of flexible acoustic coupling pad based on silicone or polyurethane is pre-attached to the radiating surface of the transducer. This pad undergoes slight deformation under pressure, perfectly filling microscopic unevenness, and has a long lifespan and requires no maintenance.

[0117] Alternative solution: liquid coupling agent injection. Microchannels and injection ports are designed at the edge of the transducer module. After installation, a small amount of high-viscosity ultrasonic coupling agent is injected through a micro pump to fill the interface.

[0118] In terms of heat dissipation design, the backing of the transducer module is in close contact with the mounting base (usually aluminum alloy). The mounting base has embedded cooling channels that are connected in series or parallel with the liquid cooling system of the battery module to achieve active heat dissipation.

[0119] Cylindrical cell battery module, square appearance, adaptive clamp-type curved surface bonding structure:

[0120] Detailed structure and working mechanism:

[0121] The core challenge is that the module shell is flat, but the inside is a cylindrical battery cell. Sound waves need to penetrate the gap between the module shell and the inside. The bonding surface is still the module plane, but a larger module size needs to be considered.

[0122] The installation method uses a double-sided or multi-sided pressure plate structure, which is similar to putting a "vest" on the module;

[0123] Fitting mechanism:

[0124] The transducer array is also fabricated as a flat panel module;

[0125] A C-shaped or O-shaped rigid clamp hugs the module from both sides or around, and the above-mentioned spring pressure plate mechanism is installed on the inner side of the two arms of the clamp.

[0126] By tightening the straps, screws, or hydraulic locking devices on the clamps, the pressure plates on both sides apply pressure to the module simultaneously. This design can handle a wide range of module sizes.

[0127] The coupling agent and heat dissipation are similar to those of the square module solution, employing solid coupling pads and integrated cooling channels.

[0128] Soft-pack battery module, embedded flexible array bonding structure:

[0129] Detailed structure and working mechanism:

[0130] The design concept integrates the transducer array directly into the module's own structural components to achieve the ultimate fit.

[0131] Integration method:

[0132] Option A, external type, uses a flexible transducer array, such as PVDF piezoelectric film or PZT ceramic composite material. This array can be attached to the inner or outer wall of the module like "wallpaper", and then a rigid constraint plate is used to apply uniform pressure on the outside.

[0133] Option B, built-in - has the highest integration. The transducer array is directly fabricated on the cooling plate or side plate of the module. For example, the piezoelectric ceramic sheet is bonded to the inside of the cooling plate with epoxy resin, on the side opposite to the battery cell. In this way, the cooling plate simultaneously serves as structural support, heat dissipation and sound wave conduction, resulting in the highest acoustic coupling efficiency.

[0134] In Scheme A, a flexible coupling pad is used as the coupling agent; in Scheme B, since it is a solid bonding process, the coupling agent is replaced by a solid adhesive layer such as epoxy resin, which is a permanent design.

[0135] For heat dissipation, option B has the best heat dissipation effect because the heat source (transducer) is in direct contact with the cooling plate.

[0136] Furthermore, it also includes a heat dissipation module:

[0137] The heat dissipation module includes a microchannel liquid cooling plate integrated into the mounting substrate of the high-power ultrasonic transducer array, and the liquid cooling plate is connected in series or in parallel with the battery module liquid cooling system.

[0138] A thermally conductive silicone grease or a phase change thermal pad is provided between the high-power ultrasonic transducer array and the mounting substrate.

[0139] The intelligent control unit can monitor the temperature of the transducer array and usually reduces the transmission power or suspends operation for protection when the temperature exceeds 80°C; however, in thermal runaway intervention mode, the control unit will prioritize the execution of the termination task.

[0140] Furthermore, the center-to-center spacing d of each transducer unit in the high-power ultrasonic transducer array satisfies d≤λ / 2, where λ is the wavelength of the ultrasonic wave in the acoustic coupling layer;

[0141] When the ultrasonic frequency is 1MHz, the spacing d is 0.5mm to 2.0mm.

[0142] This invention also provides specific verification embodiments:

[0143] Example 1: Laboratory principle verification experiment, such as Figure 3 As shown:

[0144] Objective: To verify whether high-intensity ultrasound can cause significant decomposition of typical battery electrolytes;

[0145] Setup: Place a 50mL open glass beaker in water tank 1. The glass beaker 2 contains 20mL of commercial electrolyte 5 and 1MLiPF6in EC / DMC. Immerse the ultrasonic amplitude rod probe 3 with a working frequency of 40kHz and a rated power of 100W 1cm below the surface of electrolyte 5.

[0146] Procedure: Start ultrasonic generator 4 and operate at maximum power for 5 minutes;

[0147] Observation and detection: Electrolyte 5 was observed to gradually turn yellow and become turbid, accompanied by the generation of a small number of bubbles 6; after the reaction was completed, GC-MS analysis showed that electrolyte decomposition products such as ethylene C2H4 and carbon dioxide CO2 could be detected; ion chromatography showed that the concentration of fluoride ions F- increased, proving that LiPF6 had decomposed. This experiment verified that ultrasound can effectively decompose electrolyte.

[0148] Example 2: Conceptual System Design Applied to 18650 Battery Modules

[0149] Objective: To describe a complete system concept;

[0150] System: The design includes a sleeve 9 that can be fitted over the 18650 battery module. Multiple 1MHz ultrasonic transducer units 11 are tightly arranged on the inner wall 10 of the sleeve. The space between the ultrasonic transducer units 11 and the battery module shell 7 is filled with ultrasonic coupling silicone.

[0151] Process: When the BMS detects an internal short circuit in a cell of the module, it triggers the ultrasonic system to work; the ultrasonic system first emits a set of low-power sweep frequency signals, and uses the feedback signal to initially locate the abnormal heating point area, and then emits high-power, focused pulse ultrasound waves in the direction of the area for 500ms.

[0152] Expected effect: Ultrasonic waves penetrate the steel casing of the battery and stimulate a strong cavitation effect in the electrolyte inside the target cell, causing it to decompose and fail rapidly, thus nipping thermal runaway in the bud.

[0153] like Figure 4 As shown, the transducer unit spacing of this invention is regular, and the layout logic is as follows:

[0154] The primary goal of designing the transducer unit spacing d is to avoid the acoustic grating lobe effect and ensure effective electronic focusing. The core rule is that the spacing must be less than half the wavelength λ of the ultrasonic wave in the coupling layer / battery casing medium, i.e., d≤λ / 2.

[0155] Specific layout logic for different modules:

[0156] General Computing Fundamentals:

[0157] Taking a preferred frequency of 1MHz as an example, the wavelengths λ of ultrasound in typical acoustic coupling agents, such as silicone with a sound velocity of ~1000m / s, or aluminum with a sound velocity of ~6300m / s, are approximately 1.0mm and 6.3mm, respectively.

[0158] For safety reasons, the spacing should be calculated based on the coupling layer medium with a slower sound velocity. Therefore, d≤0.5mm is an ideal and stringent target.

[0159] Square modules, containing square, cylindrical, or pouch cells:

[0160] Layout logic: Since the module shell is planar, the transducer array is arranged in a two-dimensional planar grid pattern;

[0161] Spacing rules: The recommended center-to-center spacing d between cells is between 0.5mm and 1.5mm. When space and cost allow, it should be as close to 0.5mm as possible to obtain better focusing performance. If limited by the process, it can be relaxed to 1.5mm, but simulation verification is required to ensure that no grid lobes are generated.

[0162] Square modules composed of cylindrical battery cells, "hoop-type" application scenarios:

[0163] Layout logic: Here, "hoop type" refers to the mechanism that fits around the entire square module. The transducer array is laid out on each planar side plate of the hoop 9 according to the planar grid rules of the square module.

[0164] Spacing rules: exactly the same as the square module, d≤λ / 2, no need to design a special curved array for the internal cylindrical cell 8 shape.

[0165] Soft-pack battery module, square shape:

[0166] Layout logic: Consistent with the square module, if a flexible array is used, its units are also distributed according to a two-dimensional grid;

[0167] Spacing rules: The spacing of flexible arrays may be slightly larger, such as 1.0-2.0mm, but the design principle remains the same. The basic requirement of d≤λ / 2 must still be met to ensure beam control capability.

[0168] Heat dissipation design of transducer array:

[0169] Heat dissipation basis: A combination of active liquid cooling and passive heat conduction is used;

[0170] Heat conduction path: transducer unit → high thermal conductivity substrate, such as aluminum alloy or aluminum nitride ceramic → coolant flow channel 12;

[0171] Specific heat dissipation solution:

[0172] Integrated liquid cooling plate design:

[0173] Description: The mounting substrate of the transducer array is directly designed as a microchannel liquid cooling plate, with flow channels etched or milled inside the cooling plate, serving as a parallel branch of the battery module liquid cooling system;

[0174] Work process: Coolant (such as ethylene glycol aqueous solution) is diverted from the main cooling circuit of the module into the transducer cooling plate, where it carries away heat and then flows back to the main circuit;

[0175] Advantages: Extremely high heat dissipation efficiency, low thermal resistance, integrated with the battery thermal management system, eliminating the need for a separate heat dissipation system.

[0176] Applications of Thermal Interface Material (TIM):

[0177] Description: Fill the space between the transducer unit (especially its backing) and the cooling substrate with a thermally conductive grease or phase change thermal pad with high thermal conductivity to eliminate air gaps and optimize the heat conduction path.

[0178] Operating modes and thermal management strategies:

[0179] Description: The system adopts a pulse working mode, which is inherently beneficial for reducing the average heat load. The intelligent control unit monitors the transducer temperature in real time through embedded thermocouples.

[0180] Control strategy: Normally, when the temperature exceeds a set threshold (such as 80°C), the system can automatically reduce the transmission power or suspend operation, and resume operation after the temperature drops, thus achieving dynamic thermal management; however, in thermal runaway intervention mode, the control unit will prioritize the execution of the terminated task.

[0181] This invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims.

Claims

1. A method for internal termination of battery thermal runaway based on acoustic cavitation effect, characterized in that, include: Step 1: Obtain the thermal runaway early warning signal of the new energy battery containing liquid electrolyte. The early warning signal is identified by the battery management system through the battery's multi-parameter sensors. Step 2: Apply high-intensity ultrasound to the battery so that the high-intensity ultrasound can penetrate the battery casing and propagate in the internal liquid electrolyte. Step 3: High-intensity ultrasound is used to excite acoustic cavitation effect in liquid electrolyte. Acoustic cavitation effect generates micron-sized microbubbles. The microbubbles collapse violently under the positive pressure phase of the acoustic wave and generate a high temperature of not less than 5000K and a high pressure of not less than 1000atm. Step 4: The liquid electrolyte molecules are subjected to pyrolysis, supercritical oxidation, or mechanical pyrolysis under high temperature and high pressure, causing irreversible destruction of their chemical structure and loss of ionic conductivity. Step 5: Determine if the liquid electrolyte has failed and terminate the battery thermal runaway.

2. The method for internal termination of battery thermal runaway based on acoustic cavitation effect according to claim 1, characterized in that, In step 2, the frequency range of the high-intensity ultrasound is 500 kHz to 1.5 MHz.

3. The method for internal termination of battery thermal runaway based on acoustic cavitation effect according to claim 1, characterized in that, In step 2, the high-intensity ultrasound operates in a high-frequency pulse mode. The pulse width of the high-frequency pulse mode is 1 μs to 100 μs, the pulse repetition frequency is 10 Hz to 1 kHz, and the ultrasonic intensity is not less than 10 W / cm². 2 Peak sound intensity is 10 W / cm 2 Up to 1000W / cm 2 .

4. The method for internal termination of battery thermal runaway based on acoustic cavitation effect according to claim 1, characterized in that, In step 2, high-intensity ultrasonic waves are applied by a high-power ultrasonic transducer array. The high-power ultrasonic transducer array is tightly attached to the battery shell, and an acoustic coupling layer is provided between the two. The acoustic coupling layer is a silicone pad, a polyurethane-based flexible coupling pad, or a high-viscosity liquid ultrasonic coupling agent. If it is a liquid coupling agent, it is injected through a microchannel pre-set at the edge of the transducer array.

5. The method for internal termination of battery thermal runaway based on acoustic cavitation effect according to claim 1, characterized in that, Step 2 also includes a beam localization and focusing step: A low-power sweep frequency signal of 20kHz to 100kHz is emitted by a high-power ultrasonic transducer array. Combined with the echo signal or battery surface temperature data, the thermal runaway initiation area is located with a positioning accuracy of not less than millimeters. Then, the phase difference of the emitted signal of each unit of the transducer array is adjusted so that the sound beam is focused on the initiation area. After focusing, the focal size of the sound beam is not greater than 1 / 2 of the wavelength of the ultrasonic wave in the acoustic coupling layer.

6. The method for internal termination of battery thermal runaway based on acoustic cavitation effect according to claim 1, characterized in that, The criteria for determining the failure of the liquid electrolyte in step 5 include: The ionic conductivity of the liquid electrolyte drops to 10. -4 S / cm or less; the battery temperature rise rate decreases from >1℃ / s to <0.1℃ / s or shows a negative slope; the battery voltage fluctuation amplitude is <10mV / s, and the pressure rise rate is <0.1kPa / s as monitored by a pressure sensor; the battery impedance modulus increases by more than 50% from its initial value in the frequency range of 1kHz to 100Hz; the CO2 or C2H4 concentration rise rate decreases to zero; all battery types can use multi-parameter fusion decision, that is, at least two of the three parameters of temperature, voltage and impedance reach the threshold, which is considered as successful termination.

7. A battery thermal runaway internal termination system based on acoustic cavitation effect, applied to the battery thermal runaway internal termination method based on acoustic cavitation effect as described in any one of claims 1 to 6, characterized in that, include: A high-power ultrasonic transducer array, composed of multiple piezoelectric ceramic transducer units, is used to emit high-intensity ultrasonic waves into new energy batteries containing liquid electrolyte. The high-intensity ultrasonic waves can penetrate the battery shell and excite acoustic cavitation effect in the liquid electrolyte. A high-frequency power amplifier, electrically connected to a high-power ultrasonic transducer array, provides kW-level peak output power to drive the transducer array to generate ultrasonic intensity of not less than 10 W / cm². 2 High-intensity ultrasound; The intelligent control unit is electrically connected to the high-frequency power amplifier and the battery management system, respectively, and is used to receive the thermal runaway early warning signal of the battery management system and control the timing, frequency, power and duration of ultrasonic wave transmission. A matching layer and coupling agent are placed between the high-power ultrasonic transducer array and the battery casing to reduce the reflection loss of sound waves at the medium interface; the system terminates the battery thermal runaway by causing the liquid electrolyte to fail through acoustic cavitation effect.

8. The battery thermal runaway internal termination system based on acoustic cavitation effect according to claim 7, characterized in that, The bonding structure between the high-power ultrasonic transducer array and the battery housing includes: The spring-loaded flat-plate bonding structure includes a flat transducer module and a pressure plate frame with a compression spring. The pressure plate frame is fixed to the battery module by bolts or quick-lock buckles, and the compression spring provides a contact pressure of 0.1MPa to 0.3MPa. The adaptive clamping structure includes a flat transducer module and a C-shaped / O-shaped rigid clamp. The clamp applies uniform pressure to the battery module through straps, screws or hydraulic locking devices. Embedded flexible bonding structures include PVDF piezoelectric film arrays, PZT ceramic composite flexible arrays, or transducer arrays bonded to the inside of the battery module cooling plate / side plate via epoxy resin.

9. The battery thermal runaway internal termination system based on acoustic cavitation effect according to claim 7, characterized in that, It also includes a heat dissipation module: The heat dissipation module includes a microchannel liquid cooling plate integrated into the mounting substrate of the high-power ultrasonic transducer array, and the liquid cooling plate is connected in series or in parallel with the battery module liquid cooling system. A thermally conductive silicone grease or a phase change thermal pad is provided between the high-power ultrasonic transducer array and the mounting substrate. The intelligent control unit can monitor the temperature of the transducer array and usually reduces the transmission power or suspends operation for protection when the temperature exceeds 80°C; however, in thermal runaway intervention mode, the control unit will prioritize the execution of the termination task.

10. The battery thermal runaway internal termination system based on acoustic cavitation effect according to claim 7, characterized in that, In a high-power ultrasonic transducer array, the center-to-center spacing d of each transducer unit satisfies d≤λ / 2, where λ is the wavelength of the ultrasonic wave in the acoustic coupling layer; When the ultrasonic frequency is 1MHz, the spacing d is 0.5mm to 2.0mm.

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