Composite phase change material, battery fire-fighting device comprising same and working method of battery fire-fighting device

Abstract

The invention relates to a composite phase-change material, a battery fire-fighting device comprising the composite phase-change material and a working method of the battery fire-fighting device, and belongs to the technical field of battery protection. The composite phase change material comprises a phase change material, a heat conduction material and nano aluminum hydroxide, the phase change material is paraffin or hydrogenated paraffin; the heat conduction material is expanded graphite or graphene; the mass ratio of the phase change material to the heat conduction material to the nano aluminum hydroxide is (7-7.5): (1.8-2.3): (0.8-1.2). The temperature control performance of the phase change material, the heat conductivity of the heat conduction material and the blocking performance of combustion of the nano aluminum hydroxide are comprehensively utilized, so that the composite phase change material replaces water to serve as a backup cooling medium, and the heat absorption layer in the battery fire protection device is endowed with rapid heat absorption and oxygen blocking effects.

Description

Technical Field

[0001] This application belongs to the field of battery protection technology, and specifically relates to composite phase change materials, battery fire-fighting devices containing the same, and their operating methods. Background Technology

[0002] Thermal runaway in lithium-ion battery energy storage systems has become a core safety concern in the industry. Existing fire suppression solutions for lithium-ion battery energy storage systems include water immersion cooling, which has drawbacks such as reacting with lithium metal to generate hydrogen gas (posing an explosion risk), causing electrical insulation failure (equipment scrap rate up to 90%), and issues like freezing at low temperatures and evaporation at high temperatures. Gas extinguishing agents such as perfluorohexanone have shortcomings, including insufficient sustained cooling capacity and inability to prevent reignition.

[0003] Experimental data shows that during thermal runaway of 18650 lithium batteries, the instantaneous temperature can reach over 800℃, igniting adjacent modules within 2 minutes, and releasing 1.5 times the heat of the same mass of gasoline. In traditional water-based cooling solutions, the reaction rate between water and lithium metal (Li) inside the battery increases exponentially with temperature: the hydrogen production rate is 0.5L / min at 25℃, but surges to 5L / min at 100℃, far exceeding the safety threshold (according to GB 50169-2016, the hydrogen concentration must be <1%). A case study of an energy storage power station accident shows that after water immersion, the battery insulation resistance dropped from 1000MΩ to 50Ω, causing a short circuit in the entire container circuit and tripling the losses. Although gaseous fire extinguishing agents such as perfluorohexanone can extinguish open flames within 10 seconds, laboratory studies show that their cooling effect only lasts for 3-5 minutes and cannot inhibit the continuous dendrite growth and electrolyte decomposition inside the battery (the internal temperature remains above 200℃), resulting in a reignition rate as high as 82%. In low-temperature environments (such as -20℃), the water tank freezes, causing the water immersion system to completely fail; in high-temperature environments (such as 60℃), the water evaporation rate reaches 0.5L / min, and the water tank is depleted within minutes, losing its continuous cooling capacity.

[0004] Therefore, there is an urgent need to provide a battery fire-fighting device that can quickly absorb heat, continuously cool down, and has high resistance to reignition. Summary of the Invention

[0005] To address the aforementioned issues, this application provides composite phase change materials, battery fire suppression devices containing the same, and methods for their operation.

[0006] The first objective of this application is a composite phase change material, comprising a phase change material, a thermally conductive material, and nano-aluminum hydroxide; The phase change material is paraffin or hydrogenated paraffin; The thermally conductive material is expanded graphite or graphene; The mass ratio of the phase change material, the thermally conductive material, and the nano-aluminum hydroxide is 7-7.5:1.8-2.3:0.8-1.2.

[0007] In a specific embodiment of this application, the mass ratio of the phase change material, the thermally conductive material, and the nano-aluminum hydroxide is 7:2:10.

[0008] In a specific embodiment of this application, the composition of the paraffin is adjusted according to the thermal runaway temperature of the battery: For example, the thermal runaway temperature curve of NMC (nickel-manganese-cobalt ternary lithium battery) shows that its thermal runaway temperature is 95°C. Preferably, the paraffin is n-eicosane (C20H42) with a melting point of 90°C. For example, in lithium iron phosphate batteries (which have a higher thermal runaway temperature), paraffin can be replaced with n-docosahexanes (C22H44) with a melting point of 110°C.

[0009] In a specific embodiment of this application, when the thermal runaway temperature of some batteries is higher, the phase change material is a hydrogenated paraffin with a phase change temperature of 120°C, so as to be suitable for higher temperature scenarios.

[0010] In a specific embodiment of this application, the expanded graphite has a particle size of 40-100 mesh and a porosity >95%; In a specific embodiment of this application, the expanded graphite is graphite that has undergone acid treatment. The acid treatment of graphite is an operation well known in the art. Here, this application does not limit the acid treatment operation of graphite. The thermal conductivity of expanded graphite obtained through acid treatment is increased to 220 W / m. K is 5 times that of natural graphite, which can accelerate the internal heat transfer of composite phase change materials. The particle size of the expanded graphite is preferably 50 mesh.

[0011] In a specific embodiment of this application, the particle size of the nano-aluminum hydroxide is 30-100nm, preferably 50nm. The introduction of the nano-aluminum hydroxide utilizes the endothermic decomposition of the alumina at 200℃ (ΔH=1960J / g), and the released alumina forms a dense barrier layer, which blocks oxygen in the battery module. The introduction of this layer increases the oxygen barrier rate to 90%.

[0012] In a specific embodiment of this application, the nano-aluminum hydroxide is nano-aluminum hydroxide that has been surface-modified with a silane coupling agent, which facilitates the dispersion of aluminum hydroxide in the composite phase change material.

[0013] In a specific embodiment of this application, the thermally conductive material is graphene, with a thermal conductivity ≥500W / m. K improves the thermal conductivity of composite materials, but increases the cost by about 30% compared to using expanded graphite.

[0014] In a specific embodiment of this application, the method for preparing the composite phase change material includes: A composite phase change material is obtained by uniformly mixing phase change material, thermally conductive material and nano-aluminum hydroxide.

[0015] In a specific embodiment of this application, the method for preparing the composite phase change material includes: The phase change material is heated to melt it, and then thermally conductive material and nano-aluminum hydroxide are added. The mixture is stirred evenly and then cooled to obtain a composite phase change material.

[0016] The third objective of this application is to provide a battery fire suppression device, including a heat-absorbing layer, a trigger valve, and an encapsulation layer; The heat-absorbing layer is attached to the surface of the battery module, the encapsulation layer completely covers the heat-absorbing layer, the trigger valve is located at the junction of the heat-absorbing layer and the encapsulation layer, and the top of the trigger valve penetrates through the encapsulation layer; The heat-absorbing layer is made of the composite phase change material.

[0017] In a specific embodiment of this application, the heat-absorbing layer is made of the composite phase change material through a molding process (such as hot pressing).

[0018] In a specific embodiment of this application, a thermally conductive silicone grease layer with a thermal conductivity of 3.0 W / m is provided between the heat-absorbing layer and the battery module. K.

[0019] In specific embodiments of this application, the thickness of the thermal grease layer is 0.05-0.12 mm, such as 0.05 nm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, or 0.12 mm.

[0020] In a specific embodiment of this application, the gap between the thermally conductive silicone grease layer and the battery module is controlled to be within 0.5 mm, and the thermal resistance is <0.02 K. m 2 / W.

[0021] In specific embodiments of this application, the thickness of the heat-absorbing layer is 1-3 mm, such as 1 nm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm.

[0022] In specific embodiments of this application, the thickness of the encapsulation layer is 0.05-0.1 mm, such as 0.05 nm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, or 0.1 mm.

[0023] In a specific embodiment of this application, the gap between the heat-absorbing layer and the battery module is less than or equal to 2 mm.

[0024] In a specific embodiment of this application, the encapsulation layer is an aluminum foil layer, such as 3003 aluminum alloy that has undergone anodizing treatment to enhance corrosion resistance.

[0025] In a specific embodiment of this application, the trigger valve is made of an alloy of bismuth and tin.

[0026] In a specific embodiment of this application, the mass ratio of bismuth to tin during mixing is adjusted according to the thermal runaway temperature of the battery: For example, the thermal runaway temperature curve of the NMC lithium battery shows that its runaway temperature is 95℃. Preferably, the mass ratio of bismuth to tin is 1:1, the melting point is 100℃±2℃, and the burst pressure is 0.1MPa, which precisely matches the thermal runaway temperature curve of the lithium battery (triggered at 95℃). For example, in lithium iron phosphate batteries (which have higher thermal runaway temperatures), the melting point of the trigger valve can be adjusted to 115°C by controlling the mass ratio of bismuth to tin.

[0027] In a specific embodiment of this application, the trigger valve is an electrically triggered valve (such as a temperature sensor-linked solenoid valve), which can shorten the response time of the trigger valve to within 1 second.

[0028] In a specific embodiment of this application, a heat insulation layer is further provided on the surface of the encapsulation layer, and the top of the trigger valve penetrates through the heat insulation layer. The material of the heat insulation layer is a material well known in the art, such as aerogel / ceramic fiber or aluminum silicate cotton.

[0029] In specific embodiments of this application, the thickness of the heat insulation layer is 2-5mm, such as 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, and 5mm.

[0030] The third objective of this application is to provide a method for operating a battery fire suppression device, including fire suppression operation, which includes heat triggering operation, cooling operation and barrier operation; The thermal triggering operation includes: when the temperature of the battery module reaches the battery thermal runaway temperature, the trigger valve absorbs heat and is triggered to disconnect. The heat-absorbing material in the absorption layer absorbs heat and undergoes a phase change. The heat-absorbing layer changes from a solid to a fluid state and flows out from the disconnected trigger valve, flowing on the surface of the battery module. The cooling process involves the continuous flow of the heat-absorbing layer. During this flow, the phase change material and nano-alumina in the heat-absorbing layer continuously absorb the latent heat of the battery module, thereby cooling the battery module. The blocking operation includes: a flowing heat-absorbing layer continuously flowing to cover the surface of the battery module; nano-aluminum hydroxide in the flowing heat-absorbing layer decomposing to generate a dense alumina layer; the dense alumina layer covering the surface of the battery module blocking oxygen supply; and phase change material in the heat-absorbing layer maintaining the temperature within the phase change temperature range to inhibit electrolyte decomposition and dendrite growth in the battery module.

[0031] In a specific embodiment of this application, it is further included to maintain normal operation, which includes: the heat-absorbing layer absorbing the heat of the battery module and keeping the battery module operating at the operating temperature, wherein the operating temperature is not higher than the highest value in the phase change temperature range of the phase change material in the heat-absorbing layer.

[0032] Compared with the prior art, this application has the following advantages: The present application discloses a composite phase change material, a battery fire-fighting device containing the same, and a method for operating thereof. The composite phase change material (including phase change material, thermally conductive material, and nano-aluminum hydroxide, referred to as PCM) comprehensively utilizes the temperature control performance of the phase change material, the thermal conductivity of the thermally conductive material, and the combustion blocking properties of nano-aluminum hydroxide. This allows the composite phase change material to replace water as a backup cooling medium, enabling the heat-absorbing layer in the battery fire-fighting device to rapidly absorb heat and play a role in blocking oxygen. Meanwhile, the fire-fighting device in this application includes a heat-absorbing layer, a trigger valve, and an encapsulation layer. Through the combination of these three components, it achieves the effects of "static encapsulation" temperature control and "dynamic" continuous heat absorption and oxygen inhibition, thus preventing reignition. The mechanism analysis is as follows: "Static wrapping" temperature control: The heat-absorbing layer absorbs the heat of the battery module and keeps the battery module operating at the working temperature; "Dynamic" continuous heat absorption and oxygen barrier to prevent reignition: By setting the trigger valve at the junction of the heat absorption layer and the encapsulation layer, and with the top of the trigger valve penetrating the encapsulation layer, and when the temperature of the battery module reaches the battery thermal runaway temperature, the trigger valve absorbs heat and is triggered to disconnect. The heat absorption layer changes from solid to fluid, and the fluid flows from the disconnection point to the outer surface of the battery module, forming continuous heat absorption. In addition, the nano-aluminum hydroxide in the heat absorption layer absorbs heat to form a dense oxygen barrier layer, which plays a role in preventing reignition.

[0033] In summary, the fire-fighting device of this application achieves rapid heat absorption, continuous cooling and prevention of reignition after thermal runaway, while avoiding the risk of chemical reaction and equipment damage, thus improving the fire safety and economy of the energy storage system.

[0034] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description and the accompanying drawings. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A schematic diagram of a battery-powered fire suppression device according to an embodiment of this application is shown; In the diagram: 10, heat absorption layer; 20, trigger valve; 30, encapsulation layer; 40, battery module; 50, heat insulation layer. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] According to certain embodiments of this application, a composite phase change material includes a phase change material, a thermally conductive material, and nano-aluminum hydroxide; The phase change material is paraffin or hydrogenated paraffin; The thermally conductive material is expanded graphite or graphene; The mass ratio of the phase change material, the thermally conductive material, and the nano-aluminum hydroxide is 7-7.5:1.8-2.3:0.8-1.2.

[0039] like Figure 1 As shown, a battery fire suppression device according to certain embodiments of this application includes a heat-absorbing layer 10, a trigger valve 20, and an encapsulation layer 30; The heat-absorbing layer 10 is attached to the surface of the battery module 40, the encapsulation layer 30 completely covers the heat-absorbing layer 10, the trigger valve 20 is disposed at the junction of the heat-absorbing layer 10 and the encapsulation layer 30, and the top of the trigger valve 20 penetrates the encapsulation layer 30. The heat-absorbing layer 10 is made of the composite phase change material described in the above embodiments; Through the cooperation of the heat-absorbing layer 10, the trigger valve 20, and the encapsulation layer 30, a synergistic mechanism of "thermal triggering - phase change cooling - flame retardant and anti-reignition" is formed, realizing the fire-fighting purpose of the battery fire-fighting device and achieving efficient fire extinguishing and continuous protection after battery thermal runaway. The working mechanism is as follows: Phase change heat absorption principle: The absorption layer 10 is on the surface of the battery module 40. Due to the high thermal conductivity of the thermally conductive material in the absorption layer 10, the heat inside the battery module 40 is accelerated to be transferred to the heat absorption layer 10, avoiding local overheating of the battery module 40. The heat absorbed by the absorption layer 10 is used to provide phase change for the phase change material in the absorption layer 10 (if the heat is insufficient for the phase change material to undergo phase change), thereby reducing the temperature of the battery module 40, maintaining the battery module 40 within the operating temperature range, and ensuring the normal operation of the battery module 40.

[0040] Thermal triggering principle: When the surface of the battery module 40 reaches the battery thermal runaway temperature, the thermally conductive material in the absorption layer 10 quickly absorbs a large amount of latent heat from the battery module 40, causing all the phase change material to become liquid. At the same time, the absorption layer 10 becomes fluid due to the large amount of liquid phase change material. At this time, the trigger valve 20 is triggered at the battery thermal runaway temperature and automatically disconnects. The fluidized absorption layer 10 flows out from the disconnection point and quickly covers the surface of the battery module 40, further absorbing heat from the battery module 40, reducing the temperature of the battery module 40, and controlling the absorption of the battery module 40 to be below the battery thermal runaway temperature. The flowing heat-absorbing layer 10 continuously flows and covers the surface of the battery module 40. During the flow, the phase change material and nano-aluminum hydroxide in the heat-absorbing layer 10 continuously absorb the heat of the battery module 40, continuously reducing the temperature of the battery module 40. When the temperature of the nano-aluminum hydroxide in the heat-absorbing layer 10 reaches 200℃, it decomposes (its heat of decomposition ΔH=1960J / g), generating a dense alumina barrier layer, which blocks the transfer of oxygen and heat, and prevents the battery module 40 from burning.

[0041] Anti-reignition principle: After the phase change material in the absorption layer 10 covers the battery surface, it continuously maintains the temperature below the phase change temperature range (below the electrolyte decomposition temperature of 120°C), while the dense alumina separator isolates oxygen and blocks the conditions for reignition. In this application, the trigger valve 20 serves the following functions: Without the trigger valve 20, the heat-absorbing layer 10 can only provide static absorption, effectively resulting in "ineffective cooling." While the heat-absorbing layer 10 appears to be attached to the battery surface, in a thermal runaway scenario, the cooling efficiency and coverage of "static contact" are completely insufficient. This "solid-state bonding" will immediately expose several problems, leading to cooling failure: First, localized high-temperature points in the battery module 40 will "burn through" the surface heat-absorbing layer, preventing internal heat dissipation. During battery thermal runaway, the local temperature at the tabs and cell edges will instantly surge to over 300°C (three times the phase transition temperature of the PCM material in the heat-absorbing layer 10). The surface PCM in contact with these points will rapidly melt and deplete its latent heat within 1-2 seconds (equivalent to "localized PCM being burned away"), while the PCM far from the high-temperature points remains solid. This solid PCM cannot actively move to the high-temperature area to fill the gap, resulting in a situation where "high-temperature points continue to heat up while other PCMs remain idle." Ultimately, the internal temperature of the cell exceeds 800°C, causing electrolyte splashing and open flames. Secondly, static PCM can only absorb the "surface heat" of battery module 40, and it is difficult to absorb the "internal heat" of battery module 40. However, the core of thermal runaway is the "violent reaction of the positive electrode material and electrolyte inside the cell"—even if the surface temperature of battery module 40 is reduced to 85°C by PCM, the internal temperature may still be above 150°C (exceeding the decomposition temperature of the electrolyte), creating the illusion of "cool surface, hot inside", and will eventually reignite. Thirdly, after the phase change, PCM will "shrink into a ball", and the coverage area will actually shrink, resulting in a significant decrease in cooling efficiency. For example, when paraffin wax undergoes a phase change, it changes from solid to liquid, although its volume expands by 8%. However, because it is sealed and fixed by aluminum foil, the liquid PCM will not flow actively, but will instead "shrink into small droplets" due to surface tension, causing the contact area with the battery to decrease from 95% to 60%.

[0042] By setting the trigger valve 20, the configuration of "static wrapping" is broken, so that "passively heat-absorbing solid PCM" becomes "actively flowing liquid cooling medium". The flowing PCM that flows out to the surface of the battery module can "flow in" along the gaps of the cell and the tab interface, directly contacting the high-temperature area inside the cell (penetration depth 5-8mm). This is equivalent to upgrading "cooling from the surface" to "cooling from both inside and outside", and the internal temperature can be reduced from 800℃ to below 320℃.

[0043] As can be seen, the flow-dynamic PCM automatically fills in high-temperature areas: the flow-dynamic PCM, through the channel disconnected by the trigger valve 20, rapidly flows to high-temperature points such as the tabs and corners under the action of gravity and internal pressure—covering 80% of the battery surface area within 3 seconds, achieving precise cooling of high-temperature points or flash points, and preventing local PCM depletion and failure. Furthermore, the flow-dynamic PCM can also solve the problem of "cool surface, hot inside".

[0044] In some embodiments of this application, a thermally conductive silicone grease layer is provided between the heat-absorbing layer 10 and the battery module 40.

[0045] In some embodiments of this application, a heat insulation layer 50 is further provided on the surface of the encapsulation layer 30, and the top of the trigger valve 20 penetrates the heat insulation layer 50. The heat insulation layer 50 is provided to delay external heat transfer to the battery module 40 and at the same time prevent internal heat from overflowing to other battery modules.

[0046] In some embodiments of this application, the thickness of the thermal grease layer is 0.05-0.12 mm.

[0047] In some embodiments of this application, the gap between the thermal grease layer and the battery module is controlled to be within 0.5 mm.

[0048] In some embodiments of this application, the thickness of the heat-absorbing layer 10 is 1-3 mm.

[0049] In some embodiments of this application, the thickness of the encapsulation layer 30 is 0.05-0.1 mm.

[0050] In some embodiments of this application, the gap between the heat-absorbing layer 10 and the battery module is less than or equal to 2 mm.

[0051] In some embodiments of this application, the thickness of the heat insulation layer 50 is 2-5 mm.

[0052] In some embodiments of this application, the trigger valve 20 is cylindrical so that the fluid dynamic heat-absorbing layer 10 flows out from the disconnection of the trigger valve 20, through the encapsulation layer 30 and the heat insulation layer 50, to the surface of the battery module 40. The cylindrical design of the trigger valve 20 takes into account thermal response, flow efficiency and installation compatibility.

[0053] In some embodiments of this application, the trigger valve 20 includes a cylindrical portion and an optimized portion disposed at the top of the cylindrical portion. The cylindrical portion is located between the heat-absorbing layer 10, the encapsulation layer 30, and the heat insulation layer 50 (to maintain the triggering and drainage functions of the trigger valve 20 and avoid performance degradation). The optimized portion is the part of the trigger valve 20 that extends through the heat insulation layer 50 and is designed to be deformable. Its shape may be irregular to adapt to extreme space-constrained scenarios.

[0054] The working method of the battery fire-fighting device according to certain embodiments of this application includes fire-fighting operation, which includes heat-triggered operation, cooling operation and barrier operation; The thermal triggering operation is as follows: when the temperature of the battery module 40 reaches the battery thermal runaway temperature, the trigger valve 20 absorbs heat and is triggered to disconnect. The heat-absorbing material in the absorption layer 10 absorbs heat and undergoes a phase change. The heat-absorbing layer 10 changes from a solid to a fluid state and flows out from the disconnected trigger valve 20, flowing on the surface of the battery module. The cooling process involves the continuous flow of the heat-absorbing layer 10. During the flow, the phase change material and nano-alumina in the heat-absorbing layer 10 continuously absorb the latent heat of the battery module 40, thereby cooling the battery module 40. The barrier operation is as follows: the flowing heat-absorbing layer 10 continues to flow until it covers the surface of the battery module 40. The nano-aluminum hydroxide in the flowing heat-absorbing layer 10 decomposes to generate a dense alumina layer. The dense alumina layer covers the surface of the battery module 40, blocking the oxygen supply. The phase change material in the heat-absorbing layer 10 maintains the temperature within the phase change temperature range, inhibiting the decomposition of the electrolyte and dendrite growth in the battery module 40, and maintaining the battery insulation resistance ≥500MΩ.

[0055] In some embodiments of this application, the working method further includes maintaining normal operation, wherein the heat-absorbing layer 10 absorbs heat from the battery module 40 and keeps the battery module 40 operating at a working temperature, wherein the working temperature is not higher than the highest value in the phase change temperature range of the phase change material in the heat-absorbing layer 10.

[0056] Example 1 For NMC lithium batteries, a composite phase change material is provided, comprising: Paraffin (70wt%): n-eicosane with a melting point of 90℃ and a latent heat of phase change of 247J / g was selected; Expanded graphite (20wt%): particle size 50 mesh, porosity >95%, thermal conductivity 220W / m K; Nano aluminum hydroxide (10wt%): Particle size 50nm, surface modified with silane coupling agent (any silane coupling agent, amount 1wt%), decomposes endothermally at 200℃ (ΔH=1960J / g), and the released aluminum oxide forms a dense barrier layer, increasing the oxygen barrier rate to 90%.

[0057] Example 2 A battery fire suppression device is provided for NMC lithium batteries, comprising: The heat-absorbing layer 10 is made of the composite material provided in Example 1 and has a thickness of 2 mm; The trigger valve 20 is made of a low-melting alloy of 50wt% bismuth (Bi) + 50wt% tin (Sn), with a melting point of 100℃±2℃ and a cylindrical shape with a diameter of 5mm. The encapsulation layer 30 is made of 3003 aluminum alloy with enhanced corrosion resistance through anodizing treatment, and has a thickness of 0.1 mm. The encapsulation layer 30 and the heat-absorbing layer 10 are heat-sealed to ensure stable encapsulation of the heat-absorbing layer 10 during normal operation of the battery module 40. At the same time, the edges of the encapsulation layer 30 are sealed by laser welding to ensure that the heat-absorbing layer 10 does not leak. Thermal grease layer: with a thermal conductivity of 3.0 W / m K-type thermally conductive silicone grease is applied to the surface of the battery module, with a thickness of 0.1 mm. The gap between the grease and the battery module is controlled within 0.5 mm, and the thermal resistance is <0.02 K. m 2 / W; Insulation layer 50: 5mm thick aluminum silicate cotton.

[0058] The fire-fighting operation of the battery fire-fighting device in Example 2 includes: Phase 1: Thermal Runaway Trigger Phase (95-100℃): When the NMC battery module reaches 95℃ due to thermal runaway, heat is transferred through the thermal grease (0.1mm thick, thermal conductivity 3.0W / m). K) is transferred to the heat absorption layer 10 and the trigger valve 20; when the temperature reaches the melting point of the melting alloy of the trigger valve 20 (100℃±2℃), the low melting alloy melts and breaks, forming a channel with a diameter of about 5mm; under the action of gravity and internal pressure (0.05MPa), the material of the heat absorption layer 10 flows out within 3 seconds and covers 80% of the battery surface area.

[0059] Phase 2: Phase Change Cooling Phase (0-3 minutes): The paraffin in the heat-absorbing layer 10 absorbs the heat released by the battery, changing from solid to liquid, causing the battery surface temperature to drop rapidly from 300℃ to 85℃; the expanded graphite efficiently conducts the heat inside the battery to the heat-absorbing layer 10, preventing the internal temperature of the battery module 40 from continuously rising; the encapsulation layer 30 (0.1mm thick 3003 aluminum alloy) assists in heat transfer due to its high thermal conductivity, while the outer 5mm thick aluminum silicate cotton insulation layer 50 reduces the diffusion of heat to the surrounding modules.

[0060] Phase 3: Nano-aluminum hydroxide decomposes to generate a dense alumina separator layer, covering the battery surface, increasing the oxygen barrier rate to 90% and blocking the oxygen supply; the phase change material in the heat absorption layer 10 continuously maintains the temperature below 85℃ through phase change, inhibiting electrolyte decomposition and dendrite growth; throughout the process, the battery insulation resistance remains ≥500MΩ, no hydrogen is generated, and secondary risks are avoided.

[0061] Through the synergistic effect of the above stages, the system achieves rapid cooling after thermal runaway, is expected to achieve zero reignition rate, and can be reused ≥5 times, suitable for environments from -40℃ to 80℃.

[0062] The battery fire-fighting device of Example 2 was compared with the existing technical solution, and the comparison results are shown in Table 1.

[0063] Table 1

[0064] As can be seen from the data in Table 1, the battery fire suppression device of this application has excellent safety, environmental adaptability, low equipment wear and tear, and low reignition rate.

[0065] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A composite phase change material, characterized in that, This includes phase change materials, thermally conductive materials, and nano-aluminum hydroxide; The phase change material is paraffin or hydrogenated paraffin; The thermally conductive material is expanded graphite or graphene; The mass ratio of the phase change material, the thermally conductive material, and the nano-aluminum hydroxide is 7-7.5:1.8-2.3:0.8-1.

2.

2. The composite phase change material according to claim 1, characterized in that, The mass ratio of the phase change material, the thermally conductive material, and the nano-aluminum hydroxide is 7:2:

10.

3. The composite phase change material according to claim 1, characterized in that, The composition of the paraffin is adjusted according to the thermal runaway temperature of the battery.

4. A composite phase change material according to any one of claims 1-3, characterized in that, The expanded graphite has a particle size of 40-100 mesh; And / or, The nano-aluminum hydroxide is nano-aluminum hydroxide with a surface modified by a silane coupling agent; And / or, The particle size of the nano-aluminum hydroxide is 30-100 nm.

5. A battery-powered fire suppression device, characterized in that, Includes a heat absorption layer, a trigger valve, and an encapsulation layer; The heat-absorbing layer is attached to the surface of the battery module, the encapsulation layer completely covers the heat-absorbing layer, the trigger valve is located at the junction of the heat-absorbing layer and the encapsulation layer, and the top of the trigger valve penetrates through the encapsulation layer; The heat-absorbing layer is made of a composite phase change material as described in any one of claims 1-4.

6. A battery-powered fire suppression device according to claim 5, characterized in that, A thermally conductive silicone grease layer is provided between the heat-absorbing layer and the battery module; And / or, the thickness of the thermal grease layer is 0.05-0.12 mm; And / or, the thickness of the heat-absorbing layer is 1-3 mm; And / or, the thickness of the encapsulation layer is 0.05-0.1 mm; And / or, the gap between the heat-absorbing layer and the battery module is less than or equal to 2 mm.

7. A battery fire suppression device according to claim 5, characterized in that, The trigger valve is made of an alloy of bismuth and tin; And / or, the mass ratio of bismuth to tin when mixed is adjusted according to the thermal runaway temperature of the battery.

8. A battery-powered fire suppression device according to any one of claims 5-6, characterized in that, The trigger valve is an electrically triggered valve; And / or, a heat insulation layer is further provided on the surface of the encapsulation layer, and the top of the trigger valve penetrates through the heat insulation layer; And / or, the thickness of the insulation layer is 2-5 mm.

9. The method of operating a battery-powered fire suppression device according to any one of claims 5-8, characterized in that, This includes firefighting operations, which include heat-triggered operations, cooling operations, and containment operations. The thermal triggering operation is as follows: when the temperature of the battery module reaches the battery thermal runaway temperature, the trigger valve absorbs heat and is triggered to disconnect. The heat-absorbing material in the absorption layer absorbs heat and undergoes a phase change. The heat-absorbing layer changes from a solid to a fluid state and flows out from the disconnected trigger valve, flowing on the surface of the battery module. The cooling process includes: the heat-absorbing layer continuously flows, and the phase change material and nano-alumina in the heat-absorbing layer continuously absorb the latent heat of the battery module during the flow process, thereby cooling the battery module; The blocking operation includes: a flowing heat-absorbing layer continuously flowing to cover the surface of the battery module; nano-aluminum hydroxide in the flowing heat-absorbing layer decomposing to generate a dense alumina layer; the dense alumina layer covering the surface of the battery module blocking oxygen supply; and phase change material in the heat-absorbing layer maintaining the temperature within the phase change temperature range to inhibit electrolyte decomposition and dendrite growth in the battery module.

10. The operating method of the battery fire-fighting device according to claim 9, characterized in that, It also includes maintaining normal operation, which includes: the heat-absorbing layer absorbing the heat of the battery module to keep the battery module operating at the operating temperature, wherein the operating temperature is not higher than the highest value in the phase change temperature range of the phase change material in the heat-absorbing layer.

Images