A multi-level barrier protection architecture for thermal runaway of lithium battery modules

Abstract

The application discloses a multi-stage blocking protection framework for thermal runaway of a lithium battery module, comprising a composite top cover plate covering above a battery cell group, a through pressure relief flow channel being independently arranged in the composite top cover plate corresponding to the position of an explosion-proof valve of each battery cell; a plurality of pressure relief valve assemblies, each of which is arranged at the inlet of the corresponding pressure relief flow channel; a heat conduction blocking busbar connected to the electrodes of each battery cell; and a particle trapping layer for trapping solid particles and a phase change heat absorption layer for absorbing heat of hot gas flow, which are arranged in the pressure relief flow channel in sequence along the airflow direction. The overall framework forms multi-stage protection from three dimensions of heat spread, internal pressure and tail gas hazards, significantly improving the thermal runaway prevention and control capability and use safety of the lithium battery module.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery technology, specifically relating to a multi-level barrier protection architecture for thermal runaway in lithium battery modules. Background Technology

[0002] With the popularization of new energy vehicles, higher requirements are placed on the energy density and fast charging performance of power batteries. The thermal stability risks of high-energy-density batteries, such as ternary lithium batteries, cannot be ignored. Thermal runaway caused by internal short circuits or overcharging in a single cell can eject flames, high-temperature gases, and molten particles at temperatures as high as 800-1000°C through the explosion-proof valve. These ejected materials rapidly heat adjacent cells through thermal convection, thermal radiation, and thermal conduction, easily triggering a chain reaction that can lead to the entire battery pack catching fire and exploding.

[0003] The battery module and battery pack assembly with announcement number CN111725454B proposes to install a heat insulation plate with a "protective thin plate" between the cell and the top cover, attempting to allow hot airflow to break through the thin plate in one direction and escape. However, the rupture behavior of the thin plate in this method is uncontrollable and easily blocked by molten particles; it has no ability to handle the ejected high-temperature particles, resulting in significant secondary hazards; and it does not effectively block the solid heat conduction path through the electrodes and connectors. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-level barrier protection architecture for thermal runaway in lithium battery modules, so as to solve the technical problems of safety risks caused by thermal runaway and thermal conduction failure in existing battery modules.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A multi-level thermal runaway protection architecture for a lithium battery module includes a composite top cover covering a lithium battery cell assembly composed of multiple cells. The composite top cover has an independently perforated pressure relief channel corresponding to the explosion-proof valve position of each cell. Multiple pressure relief valve assemblies are provided, each located at the inlet of the pressure relief channel and the inlet is blocked. The pressure relief valve assembly is configured to actively open to connect the pressure relief channel when the temperature or pressure at the explosion-proof valve of its corresponding cell reaches a preset trigger threshold. A thermal conduction blocking busbar is used to connect the electrodes of each cell. The thermal conduction blocking busbar includes at least one thermally sensitive disconnect structure, which is configured to increase or cut off the solid thermal conduction capacity of its path when the temperature exceeds its disconnect threshold. The pressure relief channel contains, along the airflow direction, a particle trapping layer for capturing solid particles and a phase change heat absorption layer for absorbing heat from the hot airflow.

[0007] As a preferred embodiment of the present invention, the pressure relief valve assembly includes a valve housing, the bottom air inlet of the valve housing is aligned with the explosion-proof valve port, a valve core is disposed through the inside of the valve housing, the bottom end of the valve core extends to the outside of the valve housing and is fixedly connected to a valve ball, a first boss is fixedly installed on the valve core, a first spring abuts between the first boss and the bottom of the valve housing, a second boss is fixedly installed on the upper inner wall of the valve housing, a second spring abuts between the second boss and the first boss, and the valve core concentrically passes through the inner rings of the first spring and the second spring.

[0008] As a preferred embodiment of the present invention, the heat conduction blocking busbar includes a first conductive segment, a second conductive segment, and a thermal fuse connected between the first conductive segment and the second conductive segment. The thermal fuse is made of a low-melting-point bismuth-tin alloy, which conducts electricity and heat during normal operation and melts when a preset melting temperature is reached, thereby disconnecting the circuit and forming an air insulation gap.

[0009] As a further embodiment of the present invention, the valve body inlet has a chamfered edge.

[0010] As a preferred embodiment of the present invention, the particle collection layer is a porous metal foam block, which is fixed inside the pressure relief channel by clamping bolts.

[0011] As a preferred embodiment of the present invention, the phase change heat absorption layer includes a honeycomb aluminum potting frame and hydrated salt filled inside the honeycomb aluminum, and its phase change temperature is set between 200-400°C. The honeycomb aluminum potting frame is fixed inside the pressure relief channel by clamping bolts.

[0012] As a preferred embodiment of the present invention, the inlet of the pressure relief channel is provided with an internal thread, the upper outer wall of the valve body is provided with an external thread, and the valve body is threadedly mounted on the composite top cover plate.

[0013] As a preferred embodiment of the present invention, a one-way exhaust valve is fixedly installed at the outlet of the pressure relief channel to allow hot gas to be discharged outside the module and to prevent external gas or flame from flowing back.

[0014] As a further preferred embodiment of the present invention, a fixing rod is fixedly installed on the upper inner wall of the valve body, a guide rod is fixedly installed on the fixing rod, and a guide groove is opened on the top of the valve core, with the guide rod movably inserted into the inside of the guide groove.

[0015] As a further preferred embodiment of the present invention, the first spring is made of stainless steel and the second spring is made of nickel-titanium alloy;

[0016] At room temperature, the first spring has a greater contraction force than the second spring. The first spring pushes the valve core upward, causing the valve ball to seal and press against the valve body inlet. At this time, the second spring is in a contracted state.

[0017] When the trigger temperature is reached, the second spring undergoes a phase change and elongates, generating a thrust greater than that of the first spring. This thrust pushes the valve core downward, compressing the first spring and causing the valve ball at the end of the valve core to leave the valve body inlet, thus opening the flow channel.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. This invention employs an active temperature control valve, which allows the pressure relief valve assembly to actively open when the cell temperature and pressure reach a threshold, thereby achieving controllable conduction of the pressure relief channel. This ensures the directional discharge of high-temperature and high-pressure gas from faulty cells and eliminates the randomness and uncontrollability of passive thin plate breakage.

[0020] 2. This invention utilizes a built-in trapping and heat absorption structure in the pressure relief channel. First, the particle trapping layer intercepts high-temperature solid debris and burning particles. Then, the phase change heat absorption layer absorbs a large amount of heat from the hot airflow, purifying and cooling the exhaust gas step by step. This reduces the risk of the high-temperature exhaust gas igniting external combustibles, actively reduces the destructive force of the ejected material, and achieves clean pressure relief.

[0021] 3. This invention blocks thermal convection through a pressure relief channel, blocks thermal conduction through a thermally fused busbar, and blocks thermal radiation through a multi-layered insulation structure. These three paths are blocked simultaneously to form a protective closed loop. The thermally fused busbar prevents heat from being conducted outward through the metal, the active pressure relief valve group discharges high-temperature ejected material out of the module, and the particle capture and phase change heat absorption layer eliminates the radiation source and cools the module. Even if a single cell experiences severe thermal runaway, adjacent cells will not be affected by heat transfer, fundamentally curbing the chain propagation of thermal runaway and significantly improving the intrinsic safety level of the battery module. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only examples of embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a partial exploded structural diagram of an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the composite top cover plate in an embodiment of the present invention;

[0025] Figure 3 This is a cross-sectional view of the composite top cover plate in an embodiment of the present invention;

[0026] Figure 4 This is a cross-sectional view of the valve housing in an embodiment of the present invention;

[0027] Figure 5This is a schematic diagram of the structure of the heat conduction blocking busbar in an embodiment of the present invention;

[0028] Figure 6 This is a cross-sectional view of the valve core in an embodiment of the present invention.

[0029] Figure label:

[0030] 1. Composite top cover plate; 101. Pressure relief channel; 2. Battery cell; 201. Electrode; 3. Explosion-proof valve; 4. Valve shell; 401. Valve core; 4011. Guide groove; 402. Valve ball; 403. First boss; 404. First spring; 405. Second spring; 406. Second boss; 407. Fixing rod; 408. Guide rod; 409. Chamfered edge; 5. Heat conduction blocking busbar; 501. First conductive section; 502. Second conductive section; 503. Thermal fuse; 6. Particle trapping layer; 7. Phase change heat absorption layer; 8. One-way exhaust valve. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0032] In the description of the embodiments of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0033] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an integral connection, or a detachable connection; they can refer to the internal connection of two components; they can refer to a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present invention can be understood according to the specific circumstances.

[0034] See Figures 1 to 6 As shown, an embodiment of the present invention provides a multi-level thermal runaway protection architecture for a lithium battery module, including a composite top cover plate 1 covering a lithium battery cell group composed of multiple cells 2, multiple pressure relief valve assemblies, and a thermal conduction blocking busbar 5 for connecting the electrodes 201 in each cell 2.

[0035] The composite top cover plate 1 has an independently provided through pressure relief channel 101 corresponding to the explosion-proof valve 3 position of each battery cell 2; each of the multiple pressure relief valve assemblies is located at the inlet of the corresponding pressure relief channel 101 and the inlet is blocked. The pressure relief valve assembly is configured to actively open to connect the pressure relief channel 101 when the temperature or pressure at the explosion-proof valve 3 of its corresponding battery cell 2 reaches a preset trigger threshold; the heat conduction blocking busbar 5 includes at least one thermally sensitive disconnect structure. The thermally sensitive disconnect structure is configured to increase or cut off the solid heat conduction capacity of its path when the temperature exceeds its disconnect threshold; the pressure relief channel 101 is provided with a particle trapping layer 6 for capturing solid particles and a phase change heat absorption layer 7 for absorbing the heat of the hot airflow in sequence along the airflow direction.

[0036] In the above technical solution, the composite top cover plate 1 is independently equipped with a through pressure relief channel 101 for the explosion-proof valve 3 of each battery cell 2, so as to realize independent pressure relief for a single battery cell failure, and the pressure relief between each battery cell 2 does not interfere with each other, thus avoiding the overall pressure disorder caused by a single point failure.

[0037] The pressure relief valve assembly can be actively opened when the temperature and pressure of the battery cell 2 reach the threshold, so as to realize the controllable conduction of the pressure relief channel 101 and ensure the directional discharge of high temperature and high pressure gas from the faulty battery cell 2.

[0038] The thermal conduction blocking busbar 5 is equipped with a thermistor disconnect structure, which can weaken or cut off the solid thermal conduction path under high temperature environment, prevent heat from being transferred between adjacent cells 2 from the source, and suppress the lateral spread of thermal runaway.

[0039] The pressure relief channel 101 is arranged with a particle trapping layer 6 and a phase change heat absorption layer 7 in sequence. First, the particle trapping layer 6 intercepts high-temperature solid debris and burning particles. Then, the phase change heat absorption layer 7 absorbs a large amount of heat from the hot airflow, purifying and cooling the exhaust gas step by step, reducing the risk of the high-temperature exhaust gas igniting external combustibles.

[0040] The aforementioned technical approach forms a multi-level protection system from three dimensions: thermal propagation, internal pressure, and exhaust gas hazards, significantly improving the thermal runaway prevention and control capabilities and safety of lithium battery modules.

[0041] See Figures 1 to 4 As shown, the pressure relief valve assembly includes a valve housing 4. The bottom air inlet of the valve housing 4 is aligned with the outlet of the explosion-proof valve 3. A valve core 401 is disposed inside the valve housing 4. The bottom end of the valve core 401 extends to the outside of the valve housing 4 and is fixedly connected to a valve ball 402. A first boss 403 is fixedly installed on the valve core 401. A first spring 404 abuts between the first boss 403 and the bottom of the valve housing 4. A second boss 406 is fixedly installed on the upper inner wall of the valve housing 4. A second spring 405 abuts between the second boss 406 and the first boss 403. The valve core 401 is concentrically inserted through the inner rings of the first spring 404 and the second spring 405.

[0042] The above-mentioned technical solution uses the air inlet at the bottom of the valve housing 4 directly facing the explosion-proof valve 3, with a short and precise air intake path. It can detect the temperature and pressure changes on the pressure relief side of the battery cell 2 in real time. The bottom end of the valve core 401 is connected to the valve ball 402, which is used to achieve the opening and closing sealing of the valve housing 4 inlet. The sealing surface has a high degree of fit. The first spring 404 and the second spring 405 abut against the first boss 403 and the second boss 406 respectively, and the valve core 401 is coaxially inserted into the inner ring of the two springs. The force is evenly distributed, which can avoid the valve core 401 from being stuck due to uneven load. The whole mechanical transmission structure is simple and reliable. The automatic opening and closing of the pressure relief valve assembly can be completed by relying on the spring cooperation. It has a sensitive response and can be adapted to the working environment of lithium battery modules for a long time.

[0043] See Figure 5 As shown, the heat conduction blocking busbar 5 includes a first conductive section 501, a second conductive section 502, and a thermal fuse 503 connected between the first conductive section 501 and the second conductive section 502. The thermal fuse 503 is made of a low melting point bismuth-tin alloy, which conducts electricity and heat during normal operation and melts when the preset melting temperature is reached, thereby breaking the circuit and forming an air insulation gap.

[0044] Under normal operating conditions, the first conductive section 501 and the second conductive section 502 stably conduct the circuit and transfer heat through the thermal fuse 503, which fully meets the normal charging and discharging and heat conduction requirements of the battery cell 2. When the temperature exceeds the melting threshold, the thermal fuse 503, made of low melting point bismuth-tin alloy, melts rapidly. On the one hand, it directly cuts off the electrical connection between adjacent battery cells 2, preventing the faulty battery cell 2 from continuously short-circuiting and discharging and aggravating the problem of thermal runaway. On the other hand, after melting, it forms an air insulation gap, which uses the low thermal conductivity of air to block solid heat conduction and effectively prevents heat from spreading to the surrounding battery cells 2, thus achieving dual-path isolation of electrical and thermal conduction.

[0045] See Figure 4 As shown, the inlet of valve body 4 has a chamfered edge 409 to guide the airflow to smoothly transition into the inner cavity of valve body 4, reduce turbulence and energy loss, and allow more high-temperature and high-pressure gas to be discharged quickly, preventing pressure from accumulating at the valve port.

[0046] The particulate trapping layer 6 is a porous metal foam block, which is fixed inside the pressure relief channel 101 by clamping bolts. As the particulate trapping layer 6, the porous metal foam block has dense pores and a large specific surface area, which can efficiently trap solid particles such as battery cell debris, carbon black, and metal dust ejected from the battery cell 2 during thermal runaway. This not only prevents hard particles from scratching the internal components of the pressure relief channel 101 and causing blockage, but also prevents high-temperature solid particles from causing secondary fires due to exhaust gas leakage. The particulate trapping layer 6 is fixed inside the pressure relief channel 101 by clamping bolts, which is a firm connection that can withstand the continuous scouring of high-speed, high-temperature airflow and will not shift or fall off. At the same time, the bolt connection is a detachable structure, making it easy to inspect and replace the particulate trapping layer 6 later.

[0047] The phase change heat absorption layer 7 includes a honeycomb aluminum potting frame and hydrated salt filled inside the honeycomb aluminum. Its phase change temperature is set between 200-400℃. The honeycomb aluminum potting frame is fixed inside the pressure relief channel 101 by clamping bolts. The honeycomb aluminum potting frame has high structural strength and fast thermal conductivity, which can quickly transfer the heat of the high-temperature airflow in the pressure relief channel 101 to the hydrated salt filled inside. The honeycomb channel can also extend the residence time of the hot airflow and improve the heat exchange efficiency. The phase change temperature of the hydrated salt is set at 200~400℃, which is precisely matched to the typical temperature range of the exhaust gas of lithium battery thermal runaway. During the phase change process, it can absorb a large amount of latent heat, quickly reduce the temperature of the hot airflow, weaken the ignition ability of the exhaust gas, and avoid the risk of external fire. The phase change heat absorption layer 7 is fixed inside the pressure relief channel 101 by clamping bolts, which ensures stable assembly, high temperature resistance, airflow impact resistance, and long service life of the overall heat absorption and cooling component.

[0048] See Figures 3 to 4 As shown, the inlet of the pressure relief channel 101 is provided with an internal thread, and the upper outer wall of the valve body 4 is provided with an external thread. The valve body 4 is threadedly installed on the composite top cover plate 1. The internal thread at the inlet of the pressure relief channel 101 and the external thread on the upper part of the valve body 4 cooperate with each other. The threaded connection is precisely positioned and has excellent sealing performance, which can effectively seal the assembly gaps and prevent the high-temperature and high-pressure gas of the battery cell 2 from leaking from the gaps. Moreover, this connection method is a detachable structure, and the valve body 4 and the internal pressure relief valve assembly can be removed separately for inspection and replacement in the future without disassembling the composite top cover plate 1 and the battery cell assembly as a whole, which effectively reduces the difficulty of equipment operation and maintenance and the cost of use.

[0049] See Figures 1 to 3 As shown, a one-way exhaust valve 8 is fixedly installed at the outlet of the pressure relief channel 101, allowing hot gas to be discharged outside the module and preventing the backflow of external gas or flame. The high-temperature and high-pressure gas generated by the thermal runaway of the battery cell 2 can be smoothly discharged outside the module through the one-way exhaust valve 8, ensuring that the pressure relief channel 101 is unobstructed, quickly releasing the internal pressure of the module, and avoiding pressure accumulation that could lead to an explosion. In addition, the one-way exhaust valve 8 has a one-way shut-off function, which can prevent external air, open flame, and combustion smoke from flowing back into the module, preventing external fire sources from igniting the normal battery cell 2 inside the module, cutting off the path of interconnection between internal and external fire sources, further enhancing the overall fire and explosion protection capabilities, and achieving the dual functions of directional pressure relief and prevention of flame backflow.

[0050] See Figure 6As shown, a fixing rod 407 is fixedly installed on the upper inner wall of the valve body 4, and a guide rod 408 is fixedly installed on the fixing rod 407. A guide groove 4011 is opened on the top of the valve core 401, and the guide rod 408 is movably inserted into the guide groove 4011. The fixing rod 407 inside the valve body 4 provides stable support for the guide rod 408. The guide rod 408 is movably inserted into the guide groove 4011 on the top of the valve core 401, forming an axial guide structure, which can limit the radial offset and swing of the valve core 401, avoid the valve core 401 from getting stuck or wearing unevenly during reciprocating motion, ensure that the valve ball 402 can accurately fit or disengage from the inlet of the valve body 4, and ensure the reliability of the sealing and opening and closing of the pressure relief valve assembly.

[0051] The first spring 404 is made of stainless steel, and the second spring 405 is made of nickel-titanium alloy. At room temperature, the contraction force of the first spring 404 is greater than that of the second spring 405. The first spring 404 pushes the valve core 401 upward, causing the valve ball 402 to seal and press against the inlet of the valve body 4. At this time, the second spring 405 is in a contracted state. When the trigger temperature is reached, the second spring 405 undergoes a phase change and elongates, generating a thrust greater than that of the first spring 404. This pushes the valve core 401 downward, compressing the first spring 404, causing the valve ball 402 at the end of the valve core 401 to leave the inlet of the valve body 4, and the flow channel opens.

[0052] In the above technical solution, the first spring 404 is made of stainless steel, which has stable mechanical properties, is fatigue-resistant, and high-temperature resistant. It has a greater contraction force at room temperature and can continuously push the valve core 401 upward, so that the valve ball 402 tightly presses against the inlet of the valve shell 4, ensuring that the pressure relief channel 101 is completely sealed and there is no gas leakage when the battery cell 2 is working normally. The second spring 405 is made of nickel-titanium alloy shape memory material. After reaching the preset trigger temperature, it can quickly undergo phase change elongation, generating a thrust greater than that of the first spring 404, pushing the valve core 401 downward and compressing the first spring 404, automatically opening the pressure relief channel. It has sensitive temperature response and stable trigger threshold. The two springs have clear division of labor and materials adapted to different functional requirements. They can work stably under high and low temperature and alternating operating conditions of lithium battery modules. The overall action of the pressure relief valve assembly is highly consistent, and the protection reliability is significantly improved.

[0053] Working principle of the embodiments of the present invention:

[0054] Under normal operating conditions, with no thermal runaway, the module undergoes regular charging and discharging:

[0055] The battery cell assembly is composed of multiple battery cells 2. The composite top cover 1 covers the battery cells 2. Above the explosion-proof valve 3 of each battery cell 2, there is an independent and continuous pressure relief channel 101. Each channel is independent and not connected to the others. When the pressure relief valve assembly is in a normally closed and sealed state, the valve body 4 is assembled with the external thread of the outer wall and the internal thread of the inlet of the pressure relief channel 101. The installation is firm and the sealing is good. At room temperature, the first spring 404 made of stainless steel has a greater contraction force than the second spring 405 made of nickel-titanium alloy. The first spring 404 pushes the valve core 401 upward, so that the valve ball 402 at the bottom of the valve core 401 tightly seals the air inlet at the bottom of the valve body 4, and the pressure relief channel 101 is completely closed. At the same time, the fixing rod 407 and the guide rod 408 inside the valve body 4 cooperate with the guide groove 4011 at the top of the valve core 401 to form an axial guide for the valve core 401, ensuring that the valve core 401 is centered and stable, without any risk of displacement or jamming.

[0056] When the heat conduction blocking busbar 5 is normally conducting electricity and heat, the busbar is connected as a whole by the first conductive section 501, the second conductive section 502 and the middle thermal fuse 503. The thermal fuse 503, made of bismuth-tin alloy, has excellent electrical and thermal conductivity at room temperature. The electrodes 201 of each cell 2 form a complete electrical circuit through the heat conduction blocking busbar 5, which meets the charging and discharging requirements of the module.

[0057] The internal and end components of the pressure relief channel 101 are ready for use. The particle trapping layer 6 and the phase change heat absorption layer 7 are both fixed in the channel by clamping bolts to maintain structural stability. The one-way exhaust valve 8 at the outlet of the channel is in a closed and ready state, and there is no gas flow in the entire pressure relief channel.

[0058] When a battery cell experiences thermal runaway, the protection system activates in stages:

[0059] When a single battery cell 2 experiences thermal runaway, its internal temperature and pressure rise sharply. Once the temperature and pressure at the explosion-proof valve 3 reach the preset trigger threshold, the entire protection structure will activate sequentially, achieving full-link protection against heat spread, directional pressure relief, particle interception, airflow cooling, and flame backflow.

[0060] Step 1: The pressure relief valve assembly opens automatically, establishing an independent pressure relief channel.

[0061] When the high-temperature, high-pressure gas inside the faulty cell 2 breaks through the explosion-proof valve 3, the heat and high-pressure gas flow directly act on the inside of the upper valve shell 4. The second spring 405, made of nickel-titanium alloy, undergoes a shape memory phase change and elongates when heated. Its output thrust exceeds the contraction force of the first spring 404, thus pushing the valve core 401 downward. During the downward movement of the valve core 401, the first spring 404 is compressed. At the same time, the guide rod 408 slides smoothly in the guide groove 4011, ensuring that the movement of the valve core 401 is unimpeded. The downward movement of the valve core 401 causes the bottom valve ball 402 to disengage from the bottom air inlet of the valve shell 4, and the internal channel of the valve shell 4 is opened. The high-temperature, high-pressure gas flow discharged from the cell 2 smoothly enters the dedicated pressure relief channel 101. Since each cell 2 corresponds to an independent pressure relief channel 101 and pressure relief valve assembly, a single faulty cell only opens the corresponding channel and will not affect the surrounding normal cells, achieving single-point independent pressure relief.

[0062] Step 2: Heat conduction blocking busbar 5 blocks the chain propagation of thermal runaway from the source.

[0063] Thermal fuse 503 operates as follows: When the temperature in the fault area continues to rise and reaches the melting temperature of the bismuth-tin alloy, the thermal fuse 503 melts rapidly. On the one hand, it directly disconnects the electrical connection between the first conductive segment 501 and the second conductive segment 502, cutting off the circuit between the faulty cell 2 and the surrounding cells, thus preventing the short circuit from continuing to discharge and exacerbating thermal runaway. On the other hand, after the thermal fuse 503 melts, it forms an air insulation gap between the two conductive segments. By utilizing the low thermal conductivity of air, it cuts off the solid heat conduction path, effectively curbing the lateral transmission of heat between the cell groups and preventing large-area chain thermal runaway.

[0064] Step 3: The hot gas flows through the pressure relief channel 101 to complete particle capture and forced cooling.

[0065] The high-temperature and high-pressure hot gas flows forward along the pressure relief channel 101, passing through the particle capture layer 6 and the phase change heat absorption layer 7 in sequence, thereby achieving exhaust gas purification and cooling.

[0066] Particle trapping layer 6 intercepts solid impurities: The hot airflow first comes into contact with the porous metal foam particle trapping layer 6. Its dense porous structure can efficiently capture high-temperature solid particles such as battery cell debris, metal dust, and carbon black carried in the airflow. This not only prevents hard particles from clogging the flow channel and abrading internal components, but also avoids high-temperature particles from leaking out and causing secondary fires.

[0067] The phase change heat absorption layer 7 absorbs a large amount of heat: the purified hot air enters the phase change heat absorption layer 7, and the phase change temperature of this structure is set at 200~400℃, which precisely matches the temperature range of the tail gas of the lithium battery thermal runaway; the honeycomb aluminum potting frame has a fast thermal conductivity and tortuous internal channels, which can prolong the residence time of the hot air and quickly transfer heat to the hydrated salt filled inside. The hydrated salt undergoes a solid-liquid phase change in the phase change range, absorbs a large amount of latent heat of phase change, significantly reduces the temperature of the hot air and weakens the ignition ability of the tail gas.

[0068] Step 4: One-way exhaust valve 8 vents the gas in a directional manner to prevent the external flame from flowing back.

[0069] After being purified and cooled by particles, the low-pressure, low-temperature gas reaches the outlet of the pressure relief channel 101, pushes open the one-way exhaust valve 8 and is discharged to the outside of the module, continuously releasing the internal pressure of the module to prevent pressure accumulation from causing an explosion. At the same time, the one-way exhaust valve 8 has a one-way shut-off characteristic. If there is an open flame, high-temperature smoke or flammable gas outside the module, it will be blocked by the valve and cannot flow back into the module, completely cutting off the path for external fire sources to ignite the normal internal battery cells.

[0070] Pressure relief valve assembly reset: When the internal temperature and pressure of the faulty cell 2 gradually drop below the trigger threshold, the temperature of the second spring 405 made of nickel-titanium alloy decreases, its shape is restored and it contracts, and the thrust decreases accordingly. The first spring 404 pushes the valve core 401 upward again under its own elastic force, and the valve ball 402 presses the air inlet of the valve body 4 again, and the pressure relief passage 101 is closed again.

[0071] Permanent isolation of heat conduction blocking busbar 5: After the thermal fuse 503 melts, it cannot be restored. The busbar circuit and the heat conduction path are permanently disconnected, completely isolating the faulty cell 2 from the normal cell and eliminating the risk of secondary chain reaction.

[0072] Maintainable components can be disassembled and replaced: The particle collection layer 6 and the phase change heat absorption layer 7 are fixed by clamping bolts and can be disassembled for inspection and replacement. The valve body 4 adopts a threaded connection and can be removed from the composite top cover plate 1 for maintenance without the need to disassemble the entire module, making operation and maintenance convenient.

[0073] The above description illustrates the basic principles of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The above embodiments and descriptions in the specification are only for illustrating the principles of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and scope of the present invention without departing from the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-level thermal runaway protection architecture for a lithium battery module, characterized in that... include: A composite top cover (1) covers the lithium battery cell group consisting of multiple cells (2). The composite top cover (1) has an independent through pressure relief channel (101) corresponding to the explosion-proof valve (3) of each cell (2). Multiple pressure relief valve assemblies, each of the pressure relief valve assemblies is disposed at the inlet of the corresponding pressure relief channel (101) and the inlet is blocked. The pressure relief valve assembly is configured to actively open to connect the pressure relief channel (101) when the temperature or pressure at the explosion-proof valve (3) of the corresponding battery cell (2) is sensed to reach a preset trigger threshold. A heat conduction blocking bus (5) is connected to the electrodes (201) of each of the said cells (2). The heat conduction blocking bus (5) includes at least one thermistor disconnection structure, which is configured to increase or cut off the solid heat conduction capability of the path when the temperature exceeds its disconnection threshold. The pressure relief channel (101) is provided with a particle trapping layer (6) for capturing solid particles and a phase change heat absorption layer (7) for absorbing heat from the hot airflow in sequence along the airflow direction.

2. The multi-level thermal runaway protection architecture for a lithium battery module according to claim 1, characterized in that: The pressure relief valve assembly includes a valve housing (4), the bottom air inlet of the valve housing (4) is aligned with the port of the explosion-proof valve (3), a valve core (401) is provided through the inside of the valve housing (4), the bottom end of the valve core (401) extends to the outside of the valve housing (4) and is fixedly connected to a valve ball (402), a first boss (403) is fixedly installed on the valve core (401), a first spring (404) abuts between the first boss (403) and the bottom of the valve housing (4), a second boss (406) is fixedly installed on the upper inner wall of the valve housing (4), a second spring (405) abuts between the second boss (406) and the first boss (403), and the valve core (401) is concentrically inserted through the inner ring of the first spring (404) and the second spring (405).

3. The multi-level thermal runaway protection architecture for a lithium battery module according to claim 1, characterized in that: The heat conduction blocking busbar (5) includes a first conductive segment (501), a second conductive segment (502), and a thermal fuse (503) connected between the first conductive segment (501) and the second conductive segment (502). The thermal fuse (503) is made of a low melting point bismuth-tin alloy, which conducts electricity and heat during normal operation and melts when the preset melting temperature is reached, thereby disconnecting the circuit and forming an air insulation gap.

4. The multi-level thermal runaway protection architecture for a lithium battery module according to claim 3, characterized in that: The valve body (4) has a chamfered edge (409) at the inlet.

5. The multi-level thermal runaway protection architecture for a lithium battery module according to claim 1, characterized in that: The particle trapping layer (6) is a porous metal foam block, which is fixed inside the pressure relief channel (101) by clamping bolts.

6. The multi-level thermal runaway protection architecture for a lithium battery module according to claim 1, characterized in that: The phase change heat absorption layer (7) includes a honeycomb aluminum potting frame and hydrated salt filled inside the honeycomb aluminum. Its phase change temperature is set between 200-400℃. The honeycomb aluminum potting frame is fixed inside the pressure relief channel (101) by clamping bolts.

7. The multi-level thermal runaway protection architecture for a lithium battery module according to claim 1, characterized in that: The pressure relief channel (101) has an internal thread at its inlet, and the upper outer wall of the valve body (4) has an external thread. The valve body (4) is threadedly installed on the composite top cover plate (1).

8. The multi-level thermal runaway protection architecture for a lithium battery module according to claim 1, characterized in that: A one-way exhaust valve (8) is fixedly installed at the outlet of the pressure relief channel (101).

9. A multi-level thermal runaway protection architecture for a lithium battery module according to claim 2, characterized in that: A fixing rod (407) is fixedly installed on the upper inner wall of the valve body (4), and a guide rod (408) is fixedly installed on the fixing rod (407). A guide groove (4011) is opened on the top of the valve core (401), and the guide rod (408) is movably inserted into the guide groove (4011).

10. A multi-level thermal runaway protection architecture for a lithium battery module according to claim 2, characterized in that: The first spring (404) is made of stainless steel, and the second spring (405) is made of nickel-titanium alloy; Under normal temperature conditions, the first spring (404) has a greater contraction force than the second spring (405). The first spring (404) pushes the valve core (401) upward, and the valve ball (402) seals and presses against the inlet of the valve shell (4). At this time, the second spring (405) is in a contracted state. When the trigger temperature is reached, the second spring (405) undergoes a phase change and elongates, generating a thrust greater than that of the first spring (404), which pushes the valve core (401) downward and compresses the first spring (404). The valve ball (402) at the end of the valve core (401) leaves the inlet of the valve housing (4), and the flow channel opens.

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