A front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries

Abstract

The present invention provides a front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries, belonging to the technical field of lithium-ion batteries. The front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries comprises a fixed bracket, a silicone ring, a heat insulation layer, a shock absorbing layer, a flue and a piezoelectric film sensor. The fixed bracket is clamped between the positive and negative poles of the lithium battery to provide a stable support for the installation of the device; the flue is arranged on the top of the fixed bracket, including a plurality of branch pipes, each of which is directly connected to the corresponding safety valve; the silicone ring is filled between the branch pipes of the flue and the fixed bracket; the device can solve the diffusion problem of thermal runaway gas in the battery pack, prevent the heat transfer of unburned gas to normal batteries during the thermal runaway exhaust process and the combustion heat transfer that may be generated after ignition, thereby delaying the spread of thermal runaway in the module.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and in particular relates to a front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries. Background Art

[0002] Lithium-ion batteries have been widely used in electric vehicles, grid energy storage and other fields. However, during operation, batteries may cause thermal runaway events due to mechanical, electrical, thermal abuse and other faults. Thermal runaway will cause the battery temperature to rise rapidly, and the internal chain reaction will produce a large amount of flammable gas and electrolyte vapor cloud. These gases will increase the internal pressure of the battery until the internal pressure reaches the threshold of the battery safety valve and sprays out. The released high-temperature flammable mixed gas will diffuse and flow in the battery module, where high-temperature solid particles are deposited on the surface of adjacent batteries, and part of the electrolyte vapor liquefies on the surface to release latent heat. Finally, the reaction gas transfers heat in the form of convection heat. This exhaust process will further heat the adjacent batteries and increase the risk of them entering thermal runaway. Due to the high risk of deflagration, once ignited, the high heat released by the flame combustion will also accelerate the spread of thermal runaway and even cause catastrophic consequences such as explosion. In order to prevent the discovery of such events, the existing technology usually arranges the exhaust system at the system level, such as the battery compartment level, but the back-end protection measures often have lags and cannot effectively isolate and guide these gases when the high-temperature flammable gases are first discharged. Due to the extremely fast release rate of thermal runaway gases, the current system-level exhaust solution is difficult to handle gas diffusion in a timely manner at the early stage, causing the gas to quickly diffuse into the module, bringing additional heat load to adjacent batteries, thereby accelerating the chain reaction of thermal runaway propagation. In addition, current battery packaging designs generally lack effective isolation and insulation for thermal runaway gases, resulting in high-temperature gases being able to directly contact adjacent batteries, exacerbating their surface temperature rise and further increasing the risk of them entering a thermal runaway state. This design flaw makes it impossible to effectively control the spread of high-temperature gases and flames when thermal runaway occurs, thereby increasing the possibility of catastrophic consequences such as combustion and explosion. Summary of the invention

[0003] In view of this, the present invention provides a front-end flue gas isolation and emission device for thermal runaway exhaust of lithium-ion batteries, which can solve the diffusion problem of thermal runaway gases in the battery pack, prevent the heat transfer of unburned gases to normal batteries during thermal runaway exhaust and the combustion heat transfer that may be generated after ignition, thereby delaying the spread of thermal runaway in the module.

[0004] The present invention is achieved in that:

[0005] The present invention provides a front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries, wherein a front-end smoke isolation and emission device is arranged between the safety valve of the lithium battery and the top plate of the battery pack, and the front-end smoke isolation and emission device comprises a fixed bracket, a silicone ring, a heat insulation layer, a shock absorbing layer, a flue and a piezoelectric film sensor, wherein the fixed bracket is engaged between the positive and negative poles of the lithium battery to provide a stable support for the installation of the device; the flue is arranged on the top of the fixed bracket, and comprises a plurality of branch pipes, each of which is directly connected to the corresponding safety valve; the silicone ring is filled between the branch pipes of the flue and the fixed bracket to seal the device and absorb the vibration generated after the safety valve is opened; the shock absorbing layer comprises an upper shock absorbing layer; The thermal insulation layer and the upper shock absorbing layer are arranged in sequence from bottom to top between the fixed bracket and the flue, the thermal insulation layer is used to block the heat transfer from the high-temperature gas and combustion phenomenon in the flue to the battery surface to delay the thermal runaway propagation rate of the thermal runaway battery to the adjacent battery, the upper shock absorbing layer is used to absorb the mechanical impact caused by the eruption of the thermal runaway jet to avoid the deformation and damage of the device caused by the collision between hard materials; the lower shock absorbing layer is arranged between the flue and the top plate of the battery pack, and is used to allow the mechanical impact caused by the airflow hitting the top of the flue after the battery valve is opened to be absorbed and dispersed to the surrounding area; the piezoelectric film sensor is arranged on the top of the lower shock absorbing layer, and is used to detect the pressure change at the top of the flue caused by the thermal runaway valve opening.

[0006] The technical effects of the front-end flue gas isolation and emission device for thermal runaway exhaust of lithium-ion batteries provided by the present invention are as follows: the fixed bracket provides a stable support for the device, ensuring that the entire system can remain stable in the case of thermal runaway of the lithium battery. By snapping between the positive and negative poles of the lithium battery, the bracket effectively prevents the movement or displacement of the structure caused by gas emission. The design of the flue includes multiple branch pipes, each of which is directly connected to the corresponding safety valve. This structure effectively concentrates and guides the gas discharged from the battery, reduces the risk of gas diffusion in the battery module, and ensures that the high-temperature combustible gas can be quickly introduced into the safe area for discharge. The silicone ring is used to seal between the branch pipes of the flue and the fixed bracket to prevent gas leakage. In addition, the flexible properties of the silicone material can absorb the vibration generated after the safety valve is opened, reduce the mechanical impact of the equipment, and protect the overall structure of the device. The heat insulation layer is used to block the heat transfer between the high-temperature gas and the battery surface, thereby slowing down the impact of the thermal runaway battery on the adjacent battery. The presence of this layer helps to prevent the spread of the thermal runaway phenomenon and improve the safety of the entire battery pack. The upper shock-absorbing layer absorbs the mechanical impact caused by the eruption of the thermal runaway jet and prevents collisions between hard materials. The shock-absorbing effect of this layer can effectively protect other components from damage and extend the service life of the equipment. The setting of the lower shock-absorbing layer allows the mechanical shock caused by the airflow hitting the top of the flue to be absorbed and dispersed. By dispersing the impact force, this layer protects the connection between the flue and the top plate of the battery pack and reduces possible damage. The piezoelectric film sensor is used to monitor the pressure changes at the top of the flue in real time to detect the occurrence of thermal runaway in time. This sensor setting can provide important early warning information to help quickly respond to and handle thermal runaway situations.

[0007] On the basis of the above technical solution, the front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries of the present invention can also be improved as follows:

[0008] Among them, the main flue of the flue is arranged at the top of the branch pipe; the main flue is used to guide the gas discharged from the battery to a safe area for discharge; the main flue is connected with the branch pipe to ensure that the high-temperature combustible gas erupted when the battery has thermal runaway can be directly introduced into the flue to reduce the risk of gas diffusion in the battery module.

[0009] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the setting of the main flue enables the gas discharged from the battery to be concentrated and guided to a safe area for discharge, further reducing the risk of gas diffusion inside the battery module. This structure optimizes the gas discharge path and improves the discharge efficiency.

[0010] Furthermore, a splitting plate is provided between each of the branch pipes and the main flue, and the splitting plate is used to isolate the influence of the exhaust gas of the thermal runaway battery on the adjacent batteries.

[0011] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the split disk is used to isolate the impact of the gas discharged by the thermal runaway battery on the adjacent batteries, reducing the chain reaction that may be caused by the interaction of the gases, thereby improving the safety of the overall system.

[0012] Furthermore, the fixing bracket is made of anodized aluminum, and has slots at both ends thereof corresponding to the shapes of the positive and negative poles on the top of the battery.

[0013] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the fixing bracket made of anodized aluminum material is not only high in strength and light in weight, but also has good insulation and corrosion resistance. The card slot design ensures a close fit with the battery pole, thereby improving the stability of the installation.

[0014] Furthermore, a protruding air pipe is provided in the middle position of the fixed bracket, and the protruding air pipe is connected to the safety valve port of the battery to ensure that the gas ejected by the safety valve after thermal runaway of the battery smoothly enters the flue to prevent the thermal runaway gas from diffusing to the adjacent battery position; the inner diameter of the protruding air pipe is slightly larger than the size of the safety valve and matches the outer diameter of the safety valve.

[0015] The beneficial effect of adopting the above-mentioned improvement scheme is that the protruding gas pipe directly connects to the safety valve port, ensuring that the gas ejected by the safety valve after thermal runaway can smoothly enter the flue and prevent the gas from diffusing to adjacent batteries. This design significantly improves the response speed and safety of the system.

[0016] Furthermore, the silicone ring is made of flexible silicone material to allow the fixing bracket to be slightly displaced in the horizontal direction to follow the horizontal displacement of the safety valve caused by the volume expansion of the battery due to the large amount of internal gas production before the valve opens during thermal runaway, thereby avoiding smoke leakage.

[0017] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the design of the flexible silicone ring allows slight displacement of the fixed bracket in the horizontal direction, allowing the fixed bracket to be slightly displaced in the horizontal direction to follow the volume expansion of the battery due to the large amount of internal gas production before the valve opens during thermal runaway, causing horizontal displacement of the safety valve, thereby avoiding smoke leakage.

[0018] Furthermore, the heat insulation layer is made of aluminum silicate fiber material.

[0019] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the aluminum silicate fiber material has excellent thermal insulation properties, effectively blocks the conduction of high-temperature gas, and further improves safety.

[0020] Furthermore, the upper shock-absorbing layer and the lower shock-absorbing layer are both made of high-temperature resistant foam silicone material.

[0021] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: both the upper and lower shock-absorbing layers are made of high-temperature resistant foam silicone material, which has excellent shock-absorbing effect, can effectively absorb and disperse impact, and protect other components.

[0022] Furthermore, the lower shock-absorbing layer is arranged between the flue and the piezoelectric film sensor to ensure that the piezoelectric film sensor does not fail in a high temperature environment, while dispersing the airflow impact so that the piezoelectric film sensor can detect the impact even if it is not at the exact center of the impact.

[0023] Furthermore, the piezoelectric film sensor includes a plurality of piezoelectric film sensors, which are arranged at intervals just above each battery safety valve.

[0024] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: multiple piezoelectric film sensors are arranged at intervals, which can comprehensively monitor the pressure changes at the top of the flue, improve the sensitivity and accuracy of detection, and provide a more reliable early warning for the system.

[0025] Compared with the prior art, the beneficial effects of the front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries provided by the present invention are:

[0026] The present invention effectively avoids the free diffusion of thermal runaway exhaust gas in the battery module by isolating, isolating and discharging high-temperature combustible gas at the front end of the battery safety valve. The safety valve of each battery is directly connected to the branch pipe of the flue. When the safety valve is opened, the erupted high-temperature gas can be immediately introduced into the flue and discharged centrally through the main flue to prevent the gas from diffusing to adjacent batteries. The high-temperature resistant silicone ring provides sealing for the airflow and allows slight displacement, further enhancing the flexibility and safety during the exhaust process. Through the integrated piezoelectric film sensor system, the device can detect the flow and pressure changes of thermal runaway gas in real time, quickly locate the specific battery where exhaust occurs, and start ventilation measures in the first time to prevent gas accumulation from causing explosion or fire. In addition, the device adopts a multi-layer high-temperature resistant shock-absorbing structure to absorb the vibration and impact caused by high-temperature airflow, prevent deformation or damage of hard materials, and ensure the long-term stable operation of the equipment. Compared with the prior art, the present invention innovatively controls the thermal runaway gas from the exhaust source, effectively delays the propagation of thermal runaway, and improves the overall safety of the battery module. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0028] Figure 1 It is a schematic diagram of the overall structure of a front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries;

[0029] Figure 2 This is a structural explosion diagram of a front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries;

[0030] Figure 3 It is a schematic diagram of the structure of the fixed bracket and the silicone ring;

[0031] Figure 4 The schematic diagram of the structure of the flue is shown in FIG.

[0032] Figure 5 Schematic diagram of the battery pack structure in the conventional packaging test (a) and the isolated exhaust packaging test (b);

[0033] Figure 6 Thermocouple arrangement for the experimental platform (a), conventional package test under edge heating (b), and isolated exhaust package test under intermediate heating (c);

[0034] Figure 7 The temperature variation trends of the back (a), top (c) and other locations (e) of the SOC 100% battery in the conventional packaging test under edge heating, and the temperature variation trends of the back (b), top (d) and airflow channel outlet (f) of the SOC 100% battery in the isolated exhaust packaging test;

[0035] Figure 8 The temperature variation trends of the back (a), top (c) and other positions (e) of the SOC 100% battery in the conventional packaging test under intermediate heating, and the temperature variation trends of the back (b), top (d) and airflow channel outlet (f) of the SOC 100% battery in the isolated exhaust packaging test;

[0036] Fig. 9 Comparison of the deposits on the top of the battery after testing two different battery packs;

[0037] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0038] 10. Fixed bracket; 20. Silicone ring; 30. Heat insulation layer; 40. Shock-absorbing layer; 41. Upper shock-absorbing layer; 42. Lower shock-absorbing layer; 50. Flue; 60. Piezoelectric film sensor. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0040] like Figure 1-4 As shown, it is a structural schematic diagram of a front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries provided by the present invention. In the figure, a front-end smoke isolation and emission device is arranged between the safety valve of the lithium battery and the top plate of the battery pack. The front-end smoke isolation and emission device includes a fixed bracket 10, a silicone ring 20, an insulation layer 30, a shock absorbing layer 40, a flue 50 and a piezoelectric film sensor 60. The fixed bracket 10 is engaged between the positive and negative poles of the lithium battery to provide a stable support for the installation of the device; the flue 50 is arranged on the top of the fixed bracket 10, including a plurality of branch pipes, each of which is directly connected to the corresponding safety valve; the silicone ring 20 is filled between the branch pipes of the flue 50 and the fixed bracket 10, to seal the device and absorb the vibration generated after the safety valve is opened; the shock absorbing layer 40 includes a plurality of branch pipes, each of which is directly connected to the corresponding safety valve; the silicone ring 20 is filled between the branch pipes of the flue 50 and the fixed bracket 10, to seal the device and absorb the vibration generated after the safety valve is opened; the shock absorbing layer 40 includes a plurality of branch pipes, each of which is directly connected to the corresponding safety valve; the smoke ... It includes an upper shock absorbing layer 41 and a lower shock absorbing layer 42, and the heat insulation layer 30 and the upper shock absorbing layer 41 are sequentially arranged between the fixed bracket 10 and the flue 50 from bottom to top. The heat insulation layer 30 is used to isolate the heat transfer from the high-temperature gas and combustion phenomenon in the flue 50 to the battery surface to delay the thermal runaway propagation rate of the thermal runaway battery to the adjacent battery. The upper shock absorbing layer 41 is used to absorb the mechanical impact caused by the eruption of the thermal runaway jet to avoid the deformation and damage of the device caused by the collision between hard materials; the lower shock absorbing layer 42 is arranged between the flue 50 and the top plate of the battery pack, and is used to allow the mechanical impact caused by the airflow hitting the top of the flue 50 after the battery valve is opened to be absorbed and dispersed to the surrounding area; the piezoelectric film sensor 60 is arranged on the top of the lower shock absorbing layer 42, and is used to detect the pressure change at the top of the flue 50 caused by the thermal runaway valve opening.

[0041] Among them, in the above technical solution, the main flue 50 is set at the top of the branch pipe; the main flue is used to guide the gas discharged from the battery to a safe area for discharge; the main flue is connected with the branch pipe to ensure that the high-temperature combustible gas erupted when the battery has thermal runaway can be directly introduced into the flue 50 to reduce the risk of gas diffusion in the battery module.

[0042] Furthermore, in the above technical solution, a splitting plate is provided between each branch pipe and the main flue, and the splitting plate is used to isolate the influence of the exhaust gas of the thermal runaway battery on the adjacent batteries.

[0043] Furthermore, in the above technical solution, the fixing bracket 10 is made of anodized aluminum, and slots are provided at both ends thereof, corresponding to the shapes of the positive and negative poles at the top of the battery.

[0044] Anodized aluminum is an aluminum material that has been anodized to form a dense aluminum oxide film on its surface. The oxide film can effectively protect the aluminum material from oxidation and corrosion. The surface hardness of anodized aluminum is high, which can improve its wear resistance. The oxide film is a good electrical insulator and is suitable for use in electronic components. The surface color and decorative effect can be increased by dyeing and other methods. The lightness of aluminum itself makes anodized aluminum very popular in applications that need to reduce weight.

[0045] Furthermore, in the above technical solution, a protruding air pipe is provided in the middle position of the fixed bracket 10, and the protruding air pipe is connected to the safety valve port of the battery to ensure that the gas ejected from the safety valve after thermal runaway of the battery smoothly enters the flue 50 to prevent the thermal runaway gas from diffusing to the adjacent battery position; the inner diameter of the protruding air pipe is slightly larger than the size of the safety valve and matches the outer diameter of the safety valve.

[0046] Furthermore, in the above technical solution, the silicone ring 20 is made of flexible silicone material to allow the fixing bracket 10 to be slightly displaced in the horizontal direction to follow the volume expansion of the battery due to the large amount of internal gas production before the valve opens during thermal runaway, causing horizontal displacement of the safety valve to avoid smoke leakage.

[0047] Flexible silicone is a siloxane-based polymer material with excellent elasticity, high and low temperature resistance and chemical stability. Its flexibility and durability make it widely used in many fields. It has good elasticity and softness and can adapt to a variety of shapes and sizes. It can maintain stable performance under extreme temperature conditions (usually between -60°C and 230°C). It has good resistance to most chemicals, oils and water. Good electrical insulation properties, suitable for use in electronic components and electrical equipment.

[0048] Furthermore, in the above technical solution, the heat insulation layer 30 is made of aluminum silicate fiber material.

[0049] Aluminum silicate fiber material is a high-temperature insulation material with aluminum silicate as the main component, which is widely used in various fields. It has excellent high temperature resistance and thermal insulation performance, and is usually used for thermal insulation in high temperature environments. It can withstand temperatures up to 1000°C or higher and is suitable for high temperature working environments. It has excellent thermal insulation properties, can effectively reduce heat loss and improve energy efficiency. Aluminum silicate fiber material has low density and is easy to transport and install. It has good tolerance to many chemicals. It can still maintain high strength and stability under high temperature conditions.

[0050] Furthermore, in the above technical solution, the upper shock-absorbing layer 41 and the lower shock-absorbing layer 42 are both made of high-temperature resistant foam silicone material.

[0051] Foam silicone material is a lightweight, porous silicone material that is widely used in many fields due to its unique physical and chemical properties. It combines the elasticity of silicone with the lightness of foam, and has excellent sound absorption, heat insulation and shock absorption properties. The foam structure makes it low in density, which is convenient for transportation and use. It has good compression recovery and can quickly return to its original shape. It can withstand high temperature environments and can usually withstand temperatures ranging from -60°C to 230°C. It has good waterproof properties and is suitable for humid environments. It has good resistance to many chemicals and is resistant to aging.

[0052] Furthermore, in the above technical solution, the lower shock-absorbing layer 42 is arranged between the flue 50 and the piezoelectric film sensor 60 to ensure that the piezoelectric film sensor 60 does not fail in a high temperature environment, while dispersing the airflow impact so that even the piezoelectric film sensor 60 that is not at the exact center of the impact can detect the impact.

[0053] Furthermore, in the above technical solution, the piezoelectric film sensor 60 includes a plurality of piezoelectric film sensors 60, which are arranged at intervals just above each battery safety valve. Example

[0054] The existing battery pack and the battery pack equipped with a front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries were tested, wherein:

[0055] Conventional packaging (NP) testing (eg Figure 5 (a) shows): It includes four SOC100% batteries and a heating plate placed in an aluminum battery pack. The battery module is insulated with mica plates and aerogel layers to prevent fire and reduce heat loss to the environment. A mica barrier is set 25mm above the surface of the battery module to guide the thermal runaway jet discharged through the safety valve to flow in the battery module and finally discharged through the openings on both sides of the battery pack. The battery pack can simulate the internal structure of the current commercial battery pack.

[0056] Isolation Vented Packaging (IVP) testing (eg Figure 5 (b) shows that: an aerogel layer with holes, a mica board and a battery pack outer packaging are installed at the opening of the safety valve to form an air flow channel for the safety valve, and the thermal runaway exhaust jet is directly directed to the outside of the battery pack, thereby avoiding the diffusion of the thermal runaway jet in the battery module.

[0057] Figure 6 (a) shows the overall layout of the test platform, including the test battery pack, fixtures, cameras, and related measuring instruments. Two different thermal runaway scenarios are considered:

[0058] Edge heating (eg Figure 6(b)): When the first battery cell close to the heating plate experiences thermal runaway, heating is stopped immediately to explore the thermal runaway propagation mode after the thermal runaway of the edge battery.

[0059] Intermediate heating (such as Figure 6 (c) shows that: When the adjacent batteries on both sides of the heating plate experience thermal runaway at the same time, heating is stopped to explore the thermal runaway propagation mode after the thermal runaway of the battery in the middle.

[0060] The experimental results are as follows Figure 7 , Figure 8 and Fig. 9 shown.

[0061] like Figure 7 As shown in the figure, in the case of edge heating, the temperature curve of the conventional packaging test shows that all batteries have thermal runaway. As the thermal runaway spreads within the module, the intensity and propagation rate of the thermal runaway increase, and the battery surface temperature and mass loss rate also increase. The average propagation time of thermal runaway is 492 seconds. In the isolated exhaust packaging test, the last two batteries did not experience thermal runaway. The isolation effect of the airflow channel made the severity of the thermal runaway of the first two batteries relatively close, and the propagation time of thermal runaway was extended to 722 seconds.

[0062] like Figure 8 As shown in the figure, for the case of middle heating, the heating plate triggers thermal runaway of two adjacent batteries at the same time. Due to the introduction of more external heat, the thermal runaway propagation behavior is faster and more severe than that of edge heating. In this scenario, thermal runaway occurred in all test batteries. Compared with the isolated venting packaging test, the batteries in the conventional packaging test started to vent earlier, and the interval time of thermal runaway propagation was shorter, with an average propagation time of 381.5 seconds, while the average propagation time of the isolated venting packaging test was 481 seconds.

[0063] Fig. 9 The comparison of the deposits on the top of the battery after the two battery packaging tests shows that there are obviously more deposits on the top of the battery in the conventional packaging test. These deposits are mainly composed of material particles and solidified electrolyte. In contrast, the deposits on the top of the battery are significantly reduced in the isolated exhaust packaging test. Since the airflow channel is introduced in the design to guide the jet directly to the outside of the battery pack, it effectively isolates the high-temperature gas from direct contact with the battery and reduces the formation of deposits.

[0064] These results all indicate that the isolated exhaust design structure can effectively delay the propagation of thermal runaway within the module or even directly block the propagation by isolating the high-temperature jet ejected by the battery thermal runaway, confirming the effectiveness of the isolated exhaust structure in controlling the propagation of thermal runaway.

[0065] Furthermore, the structure of the flue 50 may also include an anti-backflow component arranged at the connection between the main flue and the branch pipe, and the anti-backflow component is used to prevent the gas discharged by the lithium battery from flowing into the flue and then flowing back into the battery; the flue is arranged as a three-layer structure, namely a ventilation layer, a buffer layer and a hot air discharge layer, and the buffer layer and the ventilation layer and the hot air discharge layer are separated by elastic silicone, and the buffer layer is used to buffer the pressure of the ventilation layer and the hot air reflux layer.

[0066] The ventilation layer is connected to the hot gas discharge layer through a through pipe, and one side of the ventilation layer is connected to the ventilation system, which is used to fill gas into the air duct to dilute the gas discharged by the lithium battery; at the same time, a passage is formed between the ventilation layer, the through pipe and the hot gas discharge layer, so that the gas flowing into the ventilation layer pushes the gas discharged by the lithium battery to flow away from the battery, so that the battery can quickly discharge the hot gas and prevent further damage to the inside of the lithium battery.

[0067] The hot gas discharge layer of the flue adopts a progressively curved structure to reduce dead angles and eddies in gas flow; its bending radius is greater than twice the diameter of the safety valve to reduce the turbulence effect during gas flow.

[0068] The anti-backflow component adopts a Tesla-like one-way valve structure, has multiple curved flow channels, forms a complex flow path, can allow fluid to flow in one direction, and has low flow resistance; the structure of the anti-backflow component specifically includes a valve body, a valve core and a spring. The valve body is installed inside the branch pipeline and fixedly connected to the side wall of the branch pipeline. The valve core is placed inside the valve body for conveying the fluid; the spring is located between the valve body and the valve core and is responsible for keeping the valve core in a closed state. The valve core consists of a direct flow part and a curved flow part. The direct flow part is located at the center of the valve core, and the curved flow parts are distributed on both sides of the direct flow part. The curved flow part has a bending angle of 160° and is connected to the side wall of the direct flow part. There are 11 curved flow parts in total, which are arranged crosswise on both sides of the direct flow part. The direct flow end inlet of the valve body is connected to the branch pipeline. One end of the spring is fixed to the outer wall of the valve core, and the other end is fixed to the inner wall of the valve body. The valve core is made of flexible rubber material, and the number of springs is 4 to 8, which are fixed in sequence between the valve body and the valve core.

[0069] Furthermore, the heat insulation layer 30 may also be of the following structure:

[0070] It includes a heat-insulating base layer, a phase-change material layer and a flame-retardant layer. The heat-insulating base layer has a honeycomb structure and is made of aramid paper. It is connected to the phase-change material layer by an adhesive and provides support and preliminary heat insulation. The phase-change material layer is filled in the honeycomb pores of the heat-insulating base layer. The material is a paraffin / expanded graphite composite phase-change material with an irregular shape. It fits tightly with the heat-insulating base layer and absorbs and releases heat to maintain the temperature of the battery pack stable. The flame-retardant layer covers the outer surface of the phase-change material layer. The material is an intumescent flame-retardant coating. The shape is consistent with that of the phase-change material layer. It is connected to the phase-change material layer by a spraying process and improves the fire safety of the heat-insulating layer.

[0071] The honeycomb pore size of the aramid paper insulation matrix is ​​2-5mm and the wall thickness is 0.1-0.3mm, which can reduce the weight of the insulation layer to the greatest extent while ensuring the thermal insulation performance and provide sufficient supporting strength.

[0072] In the paraffin wax / expanded graphite composite phase change material, the mass fraction of paraffin wax is 70-80%, and the mass fraction of expanded graphite is 20-30%. This ratio effectively improves the thermal conductivity and heat storage capacity of the phase change material, while ensuring its good fluidity and filling properties, so that it can be fully filled in the honeycomb pores of the thermal insulation matrix.

[0073] The intumescent flame retardant coating has a thickness of 0.5-1.0 mm, which can effectively block flame and heat transfer without significantly increasing the thickness and weight of the thermal insulation layer.

[0074] A layer of thermally conductive silicone pad is arranged between the phase change material layer and the upper shock absorbing layer 41, and the thermally conductive silicone pad fills the gap between the phase change material layer and the upper shock absorbing layer 41 to improve the overall thermal conductivity of the thermal insulation layer and enhance the connection strength between the thermal insulation layer and the shell.

[0075] A plurality of ventilation holes are arranged at the bottom of the heat-insulating base layer, and the ventilation holes can promote air circulation.

[0076] The honeycomb structure of the aramid paper thermal insulation substrate layer adopts a regular hexagonal arrangement to maximize the use of space, improve the overall strength and stability of the thermal insulation substrate, and provide uniform support.

[0077] Furthermore, the upper shock absorbing layer 41 and the lower shock absorbing layer 42 may also be of the following structure:

[0078] It consists of an upper damping plate, an intermediate elastic support structure and a lower support plate. The upper damping plate is connected to the flue 50 and is planar in shape. The material is a high-damping alloy or polyurethane composite material. Its function is to absorb high-frequency vibration and impact energy. The intermediate elastic support structure connects the upper damping plate and the lower support plate. The shape is an array or honeycomb. The material is silicone rubber, EPDM rubber or other materials with high elasticity and low dynamic stiffness. Its function is to provide the main buffering and shock absorption functions, and allow a certain degree of deformation to adapt to impact loads in different directions. The lower support plate is connected to the insulation layer 30 and is planar in shape. The material is a high-strength steel plate or aluminum alloy plate. Its function is to provide support and fixation, and evenly distribute the load.

[0079] The middle elastic support structure adopts a honeycomb structure, which has the advantages of light weight, high strength, and high energy absorption, and can effectively absorb and disperse impact energy.

[0080] A plurality of connecting columns are arranged between the upper damping plate and the lower support plate, and the connecting columns penetrate the middle elastic support structure and connect the upper damping plate and the lower support plate together. The connecting columns are fixed by two bow-shaped metal rods, the thickness of which is set to 5-10mm, and the bow bending angle is between 30-45°, which effectively disperses the impact force, while ensuring the overall strength and stability of the shock-absorbing layer, and further reduces the impact on the adjacent batteries and the top piezoelectric film sensor caused by the vibration generated by the thermal runaway jet of the lithium battery.

[0081] The honeycomb unit of the middle elastic support structure is filled with damping material, such as silicone oil or magnetorheological fluid. The damping material can further improve the damping performance of the shock absorbing layer and reduce the resonance frequency.

[0082] Sealing strips are arranged around the shock-absorbing layer to prevent dust and moisture from entering the shock-absorbing layer and to improve the durability of the shock-absorbing layer.

[0083] The surface of the upper damping plate is coated with an anti-corrosion coating to improve its corrosion resistance.

[0084] Specifically, the principle of the present invention is: by isolating, isolating and discharging the exhaust at the front end of the battery exhaust, that is, the safety valve of each battery in the battery pack, the free diffusion of thermal runaway gas in the battery pack is avoided. During the thermal runaway process, the gas discharged by the lithium battery is not only high temperature, but also flammable and explosive. The unignited gas will heat the normal batteries in the battery pack, accelerate the temperature rise of the battery, and speed up the rate of thermal runaway propagation in the module; once the gas is ignited, the high heat generated by its combustion will further aggravate the propagation of thermal runaway and may cause catastrophic consequences.

Claims

1. A front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries, characterized in that: A front-end smoke isolation and emission device is arranged between the safety valve of the lithium battery and the top plate of the battery pack, and the front-end smoke isolation and emission device comprises a fixed bracket (10), a silicone ring (20), an insulation layer (30), a shock absorbing layer (40), a flue (50) and a piezoelectric film sensor (60). The fixed bracket (10) is engaged between the positive and negative poles of the lithium battery to provide a stable support for the installation of the device; the flue (50) is arranged on the top of the fixed bracket (10), and comprises a plurality of branch pipes, each of which is directly connected to the safety valve; the silicone ring (20) is filled between the branch pipes of the flue (50) and the fixed bracket (10), and is used to seal the device and absorb the vibration generated after the safety valve is opened; the shock absorbing layer (40) comprises an upper shock absorbing layer (41) and a lower shock absorbing layer (42); the heat insulation layer ( The heat-insulating layer (30) and the upper shock-absorbing layer (41) are sequentially arranged from bottom to top between the fixing bracket (10) and the flue (50); the heat-insulating layer (30) is used to block the heat transfer from the high-temperature gas and combustion phenomenon in the flue (50) to the battery surface to delay the thermal runaway propagation rate of the thermal runaway battery to the adjacent battery; the upper shock-absorbing layer (41) is used to absorb the mechanical impact caused by the eruption of the thermal runaway jet to avoid the deformation and damage of the device caused by the collision between hard materials; the lower shock-absorbing layer (42) is arranged between the flue (50) and the top plate of the battery pack to allow the mechanical impact caused by the airflow hitting the top of the flue (50) after the battery valve is opened to be absorbed and dispersed to the surrounding area; the piezoelectric film sensor (60) is arranged on the top of the lower shock-absorbing layer (42) to detect the pressure change at the top of the flue (50) caused by the instantaneous opening of the thermal runaway valve.

2. The front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries according to claim 1 is characterized in that: The main flue of the flue (50) is arranged at the top of the branch pipe; the main flue is used to guide the gas discharged from the battery to a safe area for discharge; the main flue is connected with the branch pipe to ensure that the high-temperature combustible gas erupted when the battery has thermal runaway can be directly introduced into the flue (50) to reduce the risk of gas diffusion in the battery module.

3. The front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries according to claim 2 is characterized in that: A splitting disk is arranged between each of the branch pipes and the main flue, and the splitting disk is used to isolate the influence of the exhaust gas of the thermal runaway battery on the adjacent batteries.

4. The front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries according to claim 3 is characterized in that: The fixing bracket (10) is made of anodized aluminum, and has slots at both ends thereof corresponding to the shapes of the positive and negative poles on the top of the battery.

5. The front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries according to claim 4 is characterized in that: A protruding air pipe is provided in the middle of the fixed bracket (10), and the protruding air pipe is docked at the safety valve port of the battery to ensure that the gas ejected by the safety valve after thermal runaway of the battery smoothly enters the flue (50) to prevent the thermal runaway gas from diffusing to adjacent battery positions; the inner diameter of the protruding air pipe matches the outer diameter of the safety valve.

6. The front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries according to claim 5, characterized in that: The silicone ring (20) is made of a flexible silicone material and is used to allow the fixing bracket (10) to be slightly displaced in the horizontal direction, so as to follow the volume expansion of the battery due to a large amount of gas production inside the battery before the valve is opened during thermal runaway, causing displacement of the safety valve in the horizontal direction, thereby avoiding smoke leakage.

7. The front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries according to claim 6 is characterized in that: The heat insulation layer (30) is made of aluminum silicate fiber material.

8. The front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries according to claim 7, characterized in that: The upper shock-absorbing layer (41) and the lower shock-absorbing layer (42) are both made of high-temperature resistant foam silicone material.

9. The front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries according to claim 8, characterized in that: The lower shock-absorbing layer (42) is arranged between the flue (50) and the piezoelectric film sensor (60) to ensure that the piezoelectric film sensor (60) does not fail in a high-temperature environment, and at the same time disperse the airflow impact so that the piezoelectric film sensor (60) can detect the impact even if it is not at the exact center of the impact.

10. The front-end smoke isolation and emission device for thermal runaway exhaust of lithium-ion batteries according to claim 9, characterized in that: The piezoelectric film sensor (60) comprises a plurality of piezoelectric film sensors (60) which are arranged at intervals just above each battery safety valve.

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