An aerogel-based ceramicized foamed silica gel cell heat insulation pad and a preparation method thereof

Abstract

The application belongs to the technical field of battery thermal runaway protection, and specifically discloses a ceramicized foamed silica gel battery heat insulation pad based on aerogel and a preparation method. The liquid silicone rubber is in-situ vulcanized and foamed, and the magnesium hydroxide whisker is supported, the micropore of the aerogel is reinforced in advance, then the aerogel is combined with the ceramicized silica gel to be foamed, and thus the battery heat insulation pad with excellent heat insulation and mechanical buffering is obtained. The battery heat insulation pad is designed in a layered gradient cell, the middle layer has large cells, and the two sides have small cells. When the battery is rapidly expanded in thermal runaway, the middle layer of the heat insulation pad provides compression buffering, avoids the micropores near the battery from being excessively compressed, and quickly sintered and formed into a hard and self-supporting microporous ceramic layer, so that a stable cell structure at high temperature is provided, and a persistent heat transfer blocking effect is achieved. The heat insulation pad reduces the use amount of aerogel, has a simple preparation process, is suitable for batch production, is directly cut during use, does not need complex assembly, and is suitable for thermal runaway protection of square shell batteries and blade batteries.

Description

Technical Field

[0001] This invention relates to the field of thermal runaway protection technology for new energy power battery cells, specifically to a ceramicized foamed silicone cell heat insulation pad based on aerogel and its preparation method. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the safety protection technology of power batteries is becoming increasingly important. The risk of thermal runaway in lithium batteries has become the biggest threat to battery safety. Power lithium batteries are composed of countless cells. Currently, after a single cell experiences thermal runaway, its temperature can rapidly soar to over 600℃, resulting in irreversible and violent heat release. The most important thing at this point is to prevent the spread of thermal runaway. Once thermal runaway spreads, it will trigger a chain reaction, causing the entire battery to catch fire or explode, resulting in even greater damage. To effectively prevent the spread of thermal runaway, the current main method is to place thermal insulation pads between the cells to block heat propagation. Therefore, the cell thermal insulation pads must have high temperature resistance and low thermal conductivity, effectively blocking heat transfer to adjacent cells when the cell experiences a rapid increase in temperature during thermal runaway, avoiding the "domino effect" of thermal runaway, and prolonging the heat propagation time. At the same time, the cell spacer thermal pads must provide mechanical cushioning to accommodate the expansion and contraction of the cells.

[0003] Existing battery safety requirements stipulate a 5-minute escape time for occupants after a battery thermal runaway. The soon-to-be-implemented mandatory standard GB38031-2025 (Safety Requirements for Power Batteries for Electric Vehicles) requires that the battery pack or system should not catch fire or explode after a thermal runaway caused by an internal short circuit in a single battery, and that smoke should not pose a danger to the passenger compartment within 5 minutes before and after a thermal event alarm signal is issued; it also requires that the battery completely block heat diffusion after being punctured, impacted, or even subjected to an internal short circuit.

[0004] Therefore, the development of cell thermal insulation pads is extremely urgent to ensure that the cells do not catch fire or explode during thermal runaway. Based on the characteristics of lithium battery cell thermal runaway, the thermal insulation pad material must be able to withstand temperatures above 600°C and maintain structural stability during thermal runaway, and its thermal conductivity must be below 0.03 W / (m·K).

[0005] Currently, aerogel felt and ceramicized foamed silicone are the main materials used for thermal insulation pads in battery cells. Aerogel felt can withstand temperatures above 1000℃ and has a low thermal conductivity of ≤0.020 W / (m·K). However, aerogel has poor structural strength and cushioning performance, is easily broken and sheds powder. Its microporous structure is prone to collapse during battery cell expansion and compression, resulting in its inability to maintain long-term thermal insulation performance. Ceramicized foamed silicone has excellent cushioning elasticity (compression rebound rate ≥90%) and can form a ceramic protective layer at high temperatures. However, the micropores of foamed silicone are easily compressed, and the cell structure has poor stability. During thermal runaway expansion, compression, and ablation, the number of ceramic micropores formed at high temperatures decreases, leading to reduced thermal insulation efficiency and difficulty in preventing the transfer of extreme high temperatures. Existing technologies have addressed these shortcomings. For example, Chinese Invention Patent Publication No. CN117984623B discloses a flexible inorganic aerogel composite thermal insulation felt, composed of adhesive, inorganic fibers, ceramizable fillers, and aerogel powder slurry, which is then calendered onto mica paper, thus solving the problem of fragility. Chinese Invention Patent Publication No. CN117866442B discloses a refractory ceramizable foamed silicone rubber and its preparation method and application, incorporating carbon nanotubes and other pore structure stabilizers into the foamed silicone rubber. This results in good elasticity under normal working conditions, providing excellent protection for the protective components. To achieve the purpose of buffering and shock absorption, it can quickly form a self-supporting foam ceramic body after high temperature or open flame ablation, and can maintain a high degree of cell structure retention rate, thus playing an excellent role in heat insulation and flame retardancy; Chinese invention patent publication number CN119430747A discloses a ceramicizable silicone foam aerogel sheet and its preparation method. The silicone foam aerogel sheet prepared by aerogel powder, glass powder, wollastonite, aluminum hydroxide, hydroxyl silicone oil, organosiloxane, catalyst, and hydrogen-containing silicone oil has good resilience properties, and the thermal conductivity at room temperature drops to 0.025W / (m·K).

[0006] While the above technologies have improved the cell stability and insulation effect of the cell insulation pad, under normal conditions, the insulation pad has buffering and elasticity to adapt to the volume changes of the cell during charging and discharging, reducing physical stress damage. However, when encountering high-temperature thermal runaway of the cell, the rapid expansion and compression can cause the cell of the insulation pad to be compressed, reducing the thermal insulation effect of the formed ceramic protective layer and making it difficult to prevent the spread of thermal runaway for a long time. Summary of the Invention

[0007] To buffer the volume changes of the battery cell during charging and discharging and effectively prevent thermal runaway, this invention provides a ceramicized foamed silicone battery cell thermal insulation pad based on aerogel and its preparation method. By reinforcing the micropores of the aerogel and filling them into the closed-cell pores of the ceramicized foamed silicone, a three-dimensional interpenetrating network is formed. This retains the low thermal conductivity of the aerogel while utilizing the elastic support of the silicone pores to solve the problem of aerogel fragility. More importantly, the reinforced closed-cell pores are not easily compressed during rapid expansion in thermal runaway, maintaining the closed-cell effect and effectively preventing heat propagation and extending the heat diffusion time.

[0008] To achieve the above-mentioned technical objectives, the present invention provides the following technical solution: A method for preparing an aerogel-based ceramicized foamed silicone battery core heat insulation pad includes the following steps: S1. Reinforced aerogel powder: Carbon dioxide aerogel, liquid silicone rubber, and magnesium hydroxide whiskers are dispersed at a mass ratio of 100:(10~15):(5~10) at a high speed of 1200~2000 rpm and gradually heated to 120℃. During dispersion, the liquid silicone rubber is adsorbed by the carbon dioxide aerogel and vulcanized and foamed in situ. The mixture is then cooled by a cyclone sieve. A 10~15wt% modified solution is prepared by dissolving a silane coupling agent in ethanol. The modified solution is added according to a mass ratio of 10:100 between the modified solution and the carbon dioxide aerogel. The mixture is stirred at 60~80℃ for 15~30 min and dried to obtain reinforced aerogel powder. S2. Preparation of compound A: Add 100 parts by weight of methyl vinyl silicone rubber, 40-50 parts by weight of aluminum hydroxide, 20-30 parts by weight of low melting point glass powder, and 5-10 parts by weight of mica powder to a kneader and knead for 15-25 minutes; then add 20-25 parts by weight of reinforcing aerogel powder, 5-6 parts by weight of foaming agent, and 1-3 parts by weight of crosslinking agent and knead for 5-10 minutes to obtain compound A. S3. Preparation of compound B: According to the weight parts, add 100 parts of methyl vinyl silicone rubber, 10-15 parts of hydroxyl silicone oil, 40-50 parts of aluminum hydroxide, 20-30 parts of low melting point glass powder, and 5-10 parts of mica powder to a kneader and knead for 15-25 minutes; then add 5-10 parts of reinforcing aerogel powder, 8-10 parts of foaming agent, and 1-3 parts of crosslinking agent and knead for 5-10 minutes to obtain compound B. S4. Calendering and laminating: Compound A and compound B are calendered into sheets by calendering machines. The sheets are laminated in three layers of ABA with a thickness ratio of 1:3:1 and stored in a louvered cart. S5. Foaming and vulcanization: The composite from step S4 is placed into a molding die and vulcanized and foamed at 160~180℃ for 10~20 minutes. After shaping and cooling, it is die-cut to obtain a ceramicized foamed silicone battery core heat insulation pad based on aerogel.

[0009] Preferably, the silica aerogel powder has a particle size of 50-100 μm and a pore size of 20-50 nm. Silica aerogel has a nanoscale porous structure, which can effectively prevent gaseous and solid-state heat conduction. Because its pore size is lower than the mean free path of air molecules at normal pressure, the air molecules in the aerogel pores are approximately stationary, thereby limiting convective heat transfer from the air.

[0010] Silica aerogels typically have a porosity exceeding 90%, low skeletal density, and are brittle, failing to effectively support their microporous structures. During processing and use, these microporous structures are prone to cracking and breakage. By adsorbing liquid silicone rubber and utilizing in-situ vulcanization and foaming with the liquid silicone rubber, the stability and elasticity of the aerogel pore walls are significantly enhanced while maintaining the micropore structure. This imparts elasticity and strength to the silica aerogel, facilitating subsequent mixing and processing to stabilize the microporous structure.

[0011] Preferably, the liquid silicone rubber has the following weight composition: 100 parts vinyl silicone oil, 8 parts hydroxyl silicone oil, 10 parts hydrogen-containing silicone oil, 0.2 parts platinum catalyst, and 5-10 parts diluent. More preferably, the platinum catalyst is a Castrol platinum catalyst with a concentration of 1000-10000 ppm; more preferably, the diluent is ethanol or methanol. The diluent reduces the viscosity of the liquid silicone rubber, allowing it to be adsorbed by silica aerogel at a lower viscosity. The silanol groups (Si-OH) in the hydroxyl silicone oil and the silicon-hydrogen bonds (Si-H) in the hydrogen-containing silicone oil undergo an addition reaction under the action of the platinum catalyst, directly generating hydrogen gas which rapidly escapes and forms bubbles. This in-situ foaming constructs a porous structure, transforming it into a soft elastomer with a three-dimensional network structure, enhancing the stability and elasticity of the aerogel pore walls.

[0012] Preferably, the magnesium hydroxide whiskers have a whisker diameter of 0.1-4.0 μm and a length of 5-50 μm. Magnesium hydroxide whiskers are microscopic fibrous inorganic materials. By introducing aerogel as a supporting and reinforcing material, the pressure resistance of the aerogel is increased. Its decomposition temperature is approximately 380℃, and the decomposition produces magnesium oxide and water, absorbing a large amount of heat, which can lower the temperature of combustible materials below their ignition point.

[0013] Preferably, the silane coupling agent is selected from at least one of KH-550, KH-560, and KH-570. The modified liquid is prepared using the silane coupling agent to improve the compatibility between the aerogel and silicone rubber, forming a "molecular bridge" at the silicone rubber interface.

[0014] Preferably, the methyl vinyl silicone rubber is a vinyl-terminated methyl vinyl silicone rubber raw rubber with a relative viscosity-average molecular weight of 400,000 to 600,000 and an ethylene molar content of 0.13% to 0.18%. After vulcanization, the methyl vinyl silicone rubber raw rubber exhibits high insulation, high temperature resistance, high tear strength, and excellent elasticity. It can be used for extended periods within a temperature range of -50°C to 250°C.

[0015] Preferably, the low-melting-point glass powder has a particle size of 5~10µm and an initial melting point of 500~600℃.

[0016] Preferably, the aluminum hydroxide particle size is 2~10µm. As a flame retardant, aluminum hydroxide begins to decompose and rapidly dehydrate when heated to 200℃, exhibiting an endothermic reaction to achieve flame retardancy. Simultaneously, it generates alumina, which sintersects with low-melting-point glass powder, mica layered silicates, and silica produced by the pyrolysis of silicone rubber to form a hard, self-supporting microporous ceramic layer, providing a stable pore structure at high temperatures and achieving the purpose of blocking heat transfer.

[0017] In compound A, a high content of aerogel and a low amount of foaming agent are used to form smaller pores during foaming, with an optimal pore size of 50-80 μm. In compound B, a lower content of aerogel and a higher amount of foaming agent are used, along with a low-viscosity hydroxyl silicone oil as a structure control agent, resulting in larger pores during foaming, with an optimal pore size of 200-300 μm. The thermal insulation pad obtained by vulcanizing and foaming compound A and compound B sheets using ABA three-layer lamination has a large-pore middle layer and small-pore layers on both sides. This gradient pore design, when used for cell insulation, features small pores with a high aerogel content closer to the cell to enhance insulation, while larger pores further away from the cell provide cushioning.

[0018] Preferably, the foaming agent is at least one of azodicarbonamide and 4,4'-oxobisbenzenesulfonylhydrazine.

[0019] Preferably, the crosslinking agent is at least one of DCP, DHBP, and BPO.

[0020] This invention also provides an aerogel-based ceramicized foamed silicone battery cell thermal insulation pad prepared by the above method. By pre-strengthening the micropores of the aerogel and combining it with ceramicized silicone, the battery cell thermal insulation pad acquires excellent thermal insulation and mechanical cushioning properties. The thermal insulation pad is a layered foam with a gradient pore design, featuring large pores in the middle and small pores on both sides. When used for battery cell thermal insulation, the side closer to the battery cell has small pores and a high aerogel content, significantly preventing the spread of thermal runaway. During the volume change of the battery cell during charging and discharging, the large pores in the middle layer of the thermal insulation pad provide elastic cushioning, preventing excessive compression and breakage on both sides. During the rapid expansion and compression of the battery cell due to thermal runaway, the micropores near the battery cell are not easily compressed and damaged, ensuring that the sintered ceramic layer has a continuous thermal insulation effect, effectively preventing heat diffusion and prolonging the heat diffusion time.

[0021] The advantages and beneficial effects of this invention are as follows: (1) The present invention strengthens the silica aerogel powder, which has a stable microporous structure and is not easily compressed and collapsed, thus maintaining a long-lasting heat insulation effect. Furthermore, by strengthening the aerogel, the micropores are not damaged when it is used for kneading, mixing and calendering of methyl vinyl silicone rubber, which facilitates mass production and simplifies the molding process.

[0022] (2) The present invention can be easily processed and shaped by combining the micropores of the aerogel with ceramicized silicone. The aerogel fills the closed pores of the ceramicized foamed silicone to form a three-dimensional interpenetrating network, which retains the low thermal conductivity of the aerogel and utilizes the elastic support of the silicone pores, thus having both flame retardant and heat insulation properties as well as elastic cushioning.

[0023] (3) The heat insulation pad of the present invention has a layered gradient foam design, with large foam pores in the middle layer and small foam pores on both sides. When used for heat insulation of battery cells, the side with small foam pores and high aerogel content is in close contact with the battery cell; when the battery cell expands rapidly due to thermal runaway, the middle layer of the heat insulation pad provides compression buffer, avoids excessive compression of the micropores on the side close to the battery cell, and quickly sintersects and porcelains to form a hard, self-supporting microporous ceramic layer, providing a stable foam structure at high temperature and achieving a long-lasting heat transfer barrier effect.

[0024] (4) The thermal insulation pad of the present invention reduces the amount of aerogel used, has a simple preparation process, is suitable for mass production, can be directly cut when used, does not require complex assembly, and is suitable for thermal runaway protection of square-shell cells and blade cells. Attached Figure Description

[0025] To help technicians understand, the attached diagram provides a visual illustration of the cell insulation pad.

[0026] Figure 1 This invention presents a schematic diagram of a ceramicized foamed silicone battery cell thermal insulation pad based on aerogel. Wherein: A represents the small-pore layer; B represents the large-pore layer. Detailed Implementation

[0027] The preferred embodiments of the present invention are described in detail below to make the advantages of the present invention more readily understood by those skilled in the art. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the described embodiments without inventive effort are within the scope of protection of the present invention.

[0028] Unless otherwise specified, all raw materials used are those commonly used in this field and are commercially available. The following are some of the raw material parameters: Silica aerogel powder: particle size 100μm, pore size 20~50nm, produced in Zhejiang.

[0029] Methyl vinyl silicone rubber: Type 110-2 raw rubber, with a relative viscosity-average molecular weight of 400,000 to 600,000 and an ethylene molar content of 0.13-0.18%.

[0030] Vinyl silicone oil: Vinyl-terminated polydimethylsiloxane, brand name ADL-V2A, viscosity approximately 2000 mPa·s, vinyl content 0.26%, Jiangxi Andeli High-tech Technology Co., Ltd.

[0031] Hydroxyl silicone oil: Hydroxyl-terminated polydimethylsiloxane, hydroxyl content 6%, Zhejiang Runhe Organosilicon Co., Ltd.

[0032] Hydrogen-containing silicone oil: 1-200-20, hydrogen content 0.2%, Zhejiang Chuangji Organosilicon Materials Co., Ltd.

[0033] Platinum catalyst: Castells platinum catalyst, platinum concentration of 1000 ppm.

[0034] Low melting point glass powder: Grade GT50, initial melting point 500℃, Anmi Micro-Nano New Materials (Guangzhou) Co., Ltd.

[0035] Aluminum hydroxide flame retardant: particle size 10µm, Shandong Zhonglv.

[0036] Magnesium hydroxide whiskers: diameter 0.1-3.0μm, length 5-50μm, origin Liaoning.

[0037] Example 1 S1. Reinforced Aerogel Powder: Carbon dioxide aerogel, liquid silicone rubber, and magnesium hydroxide whiskers are dispersed at a mass ratio of 100:10:10 at a high speed of 1200 rpm and gradually heated to 120℃. During dispersion, the liquid silicone rubber is adsorbed by the carbon dioxide aerogel and vulcanized and foamed in situ for 20 min. The mixture is then cooled through a cyclone sieve. A 15 wt% modified solution is prepared by dissolving silane coupling agent KH-550 in ethanol. The modified solution is added according to a mass ratio of 10:100 (modified solution to carbon dioxide aerogel). The mixture is stirred at 80℃ for 15 min and dried to obtain reinforced aerogel powder. (The liquid silicone rubber is formulated as follows: 100 parts vinyl silicone oil, 8 parts hydroxyl silicone oil, 10 parts hydrogen-containing silicone oil, 0.2 parts platinum catalyst, and 8 parts ethanol. It should be prepared fresh for use.) S2. Preparation of compound A: 100 parts by weight of methyl vinyl silicone rubber, 40 parts by weight of aluminum hydroxide flame retardant, 25 parts by weight of low melting point glass powder and 5 parts by weight of mica powder are added to a kneader and kneaded for 15 min; then 22 parts by weight of reinforcing aerogel powder, 5 parts by weight of foaming agent azodicarbonamide and 2 parts by weight of crosslinking agent DCP are added and kneaded for 5 min to obtain compound A. S3. Preparation of compound B: 100 parts by weight of methyl vinyl silicone rubber, 10 parts by weight of hydroxyl silicone oil, 50 parts by weight of aluminum hydroxide, 25 parts by weight of low melting point glass powder, and 5 parts by weight of mica powder are added to a kneader and kneaded for 15 min; then 5 parts by weight of reinforcing aerogel powder, 8 parts by weight of foaming agent azodicarbonamide, and 2 parts by weight of crosslinking agent DCP are added and kneaded for 10 min to obtain compound B; S4. Calendering and laminating: Compound A and compound B are calendered into sheets by calendering machines. The sheets are laminated in three layers of ABA with a thickness ratio of 1:3:1 and stored in a louvered cart. S5. Foaming and vulcanization: The composite from step S4 is placed into a molding die and vulcanized and foamed at 160°C for 20 minutes, so that the mainstream pore size of the outer layer is in the range of 50~80μm; the mainstream pore size of the middle layer is in the range of 200~300μm; after shaping and cooling, it is die-cut to obtain a ceramicized foamed silicone battery core heat insulation pad based on aerogel.

[0038] Example 2 S1. Reinforced Aerogel Powder: Carbon dioxide aerogel, liquid silicone rubber, and magnesium hydroxide whiskers are dispersed at a mass ratio of 100:12:8 at a high speed of 2000 rpm and gradually heated to 120℃. During dispersion, the liquid silicone rubber is adsorbed by the carbon dioxide aerogel and vulcanized and foamed in situ for 20 min. The mixture is then cooled through a cyclone sieve. A 10 wt% modified solution is prepared by dissolving silane coupling agent KH-550 in ethanol. The modified solution is added according to a mass ratio of 10:100 of modified solution to carbon dioxide aerogel. The mixture is stirred at 60℃ for 30 min and dried to obtain reinforced aerogel powder. (The liquid silicone rubber is formulated as follows: 100 parts vinyl silicone oil, 8 parts hydroxyl silicone oil, 10 parts hydrogen-containing silicone oil, 0.2 parts platinum catalyst, and 8 parts ethanol. It should be prepared fresh for use.) S2. Preparation of compound A: 100 parts by weight of methyl vinyl silicone rubber, 45 parts by weight of aluminum hydroxide flame retardant, 20 parts by weight of low melting point glass powder, and 5 parts by weight of mica powder are added to a kneader and kneaded for 25 min; then 25 parts by weight of reinforcing aerogel powder, 5 parts by weight of foaming agent 4,4'-oxobisbenzenesulfonyl hydrazine, and 2.5 parts by weight of crosslinking agent BPO are added and kneaded for 5 min to obtain compound A; S3. Preparation of compound B: 100 parts by weight of methyl vinyl silicone rubber, 10 parts by weight of hydroxyl silicone oil, 40 parts by weight of aluminum hydroxide, 20 parts by weight of low melting point glass powder, and 8 parts by weight of mica powder are added to a kneader and kneaded for 20 min; then 10 parts by weight of reinforcing aerogel powder, 8 parts by weight of foaming agent 4,4'-oxobisbenzenesulfonyl hydrazine, and 2.5 parts by weight of crosslinking agent BPO are added and kneaded for 5 min to obtain compound B; S4. Calendering and laminating: Compound A and compound B are calendered into sheets by calendering machines. The sheets are laminated in three layers of ABA with a thickness ratio of 1:3:1 and stored in a louvered cart. S5. Foaming and vulcanization: The composite from step S4 is placed into a molding die and vulcanized and foamed at 170°C for 15 minutes. The temperature and time are controlled so that the mainstream pore size of the outer layer is in the range of 50~80μm and the mainstream pore size of the middle layer is in the range of 200~300μm. After shaping and cooling, it is die-cut to obtain a ceramicized foamed silicone battery core heat insulation pad based on aerogel.

[0039] Example 3 S1. Reinforced Aerogel Powder: Carbon dioxide aerogel, liquid silicone rubber, and magnesium hydroxide whiskers are dispersed at a mass ratio of 100:15:5 at a high speed of 1200 rpm and gradually heated to 120℃. During dispersion, the liquid silicone rubber is adsorbed by the carbon dioxide aerogel and vulcanized and foamed in situ for 20 min. The mixture is then cooled through a cyclone sieve. A 10 wt% modified solution is prepared by dissolving silane coupling agent KH-560 in ethanol. The modified solution is added according to a mass ratio of 10:100 of modified solution to carbon dioxide aerogel. The mixture is stirred at 60℃ for 30 min and dried to obtain reinforced aerogel powder. (The liquid silicone rubber is formulated as follows: 100 parts vinyl silicone oil, 8 parts hydroxyl silicone oil, 10 parts hydrogen-containing silicone oil, 0.2 parts platinum catalyst, and 8 parts ethanol. It should be prepared fresh for use.) S2. Preparation of compound A: 100 parts by weight of methyl vinyl silicone rubber, 45 parts by weight of aluminum hydroxide flame retardant, 20 parts by weight of low melting point glass powder, and 5 parts by weight of mica powder are added to a kneader and kneaded for 25 min; then 20 parts by weight of reinforcing aerogel powder, 5 parts by weight of foaming agent 4,4'-oxobisbenzenesulfonyl hydrazine, and 2.5 parts by weight of crosslinking agent BPO are added and kneaded for 5 min to obtain compound A; S3. Preparation of compound B: 100 parts by weight of methyl vinyl silicone rubber, 10 parts by weight of hydroxyl silicone oil, 40 parts by weight of aluminum hydroxide, 20 parts by weight of low melting point glass powder, and 8 parts by weight of mica powder are added to a kneader and kneaded for 20 min; then 8 parts by weight of reinforcing aerogel powder, 8 parts by weight of foaming agent 4,4'-oxobisbenzenesulfonyl hydrazine, and 2.5 parts by weight of crosslinking agent BPO are added and kneaded for 5 min to obtain compound B; S4. Calendering and laminating: Compound A and compound B are calendered into sheets by calendering machines. The sheets are laminated in three layers of ABA with a thickness ratio of 1:3:1 and stored in a louvered cart. S5. Foaming and vulcanization: The composite from step S4 is placed into a molding die and vulcanized and foamed at 180°C for 10 minutes. The temperature and time are controlled so that the mainstream pore size of the outer layer is in the range of 50~80μm and the mainstream pore size of the middle layer is in the range of 200~300μm. After shaping and cooling, it is die-cut to obtain a ceramicized foamed silicone battery core heat insulation pad based on aerogel.

[0040] Comparative Example 1 The thermal insulation pad gel of Comparative Example 1 was calendered into sheets using compound A from Example 1 and then vulcanized and foamed in a molding die. Gradient cell design using an ABA three-layer lamination method was not employed.

[0041] Comparative Example 2 Comparative Example 2 followed the process of Example 1 when preparing the heat insulation pad, but without adding reinforced aerogel, directly adding an equal amount of unreinforced silica aerogel.

[0042] Comparative Example 3 Comparative Example 3 is the commercially available aerogel insulation pad (FRA-C650) from Gongyi Fanrui Yihui Composite Materials Co., Ltd. This serves as a comparison of pure aerogel insulation pads.

[0043] The thermal insulation pads from Examples 1-3 and Comparative Examples 1-3 were used to test thermal conductivity, resilience, and heat diffusion time. The test results are shown in Table 1. The specific test methods are as follows: (1) Thermal conductivity of the insulation pad: The thermal conductivity at 25℃ was determined by measuring the steady-state thermal resistance of the insulation material, referring to GB / T 10295-2008.

[0044] (2) Resilience rate of the heat insulation pad: simulate the normal expansion and compression of the battery cell during charging, compress the sample thickness to 35% at 85℃, maintain the compressed state for 22 hours, and then unload and recover. Measure the original thickness (h0) of the sample and the thickness (h1) of the sample after compression and unloading. The resilience rate is calculated as (h1 / h0) × 100%.

[0045] (3) Performance of heat insulation pad in preventing rapid temperature diffusion: simulate the temperature and expansion pressure during battery thermal runaway, compress the heat insulation pad under a compressive force of 500 kPa, and simulate the electrolyte combustion temperature during cell thermal runaway. Ceramicize the heat insulation pad at a high temperature of 675℃. When the back temperature rises to 200℃, record it as the thermal diffusion time; detect the thermal conductivity of the ceramized heat insulation pad at 25℃.

[0046] Table 1: As can be seen from the above implementation scheme and test data, the heat insulation pad of the present invention possesses excellent low thermal conductivity, high elasticity, and heat resistance performance during high-temperature ceramicization. (See attached...) Figure 1This is a schematic diagram of the aerogel-based ceramicized foamed silicone battery cell thermal insulation pad structure of the present invention (where A is the small-pore layer and B is the large-pore layer). The gradient design of the thermal insulation pad with large pores in the middle layer and small pores on both sides provides elastic buffering during high-temperature extrusion, preventing excessive compression and breakage on both sides. Ultimately, the thermal conductivity of the sintered ceramicized thermal insulation pad remains at a low level. The buffering and thermal insulation effect is superior to that of the aerogel thermal insulation pad (Comparative Example 3). In contrast, the thermal insulation pads in Comparative Example 1 all feature a low-pore, high-aerogel design, resulting in lower thermal conductivity but poorer pressure resistance. During high-temperature ceramicization under extrusion, the pores are severely compressed, damaging the aerogel pores and causing an increase in thermal conductivity after high-temperature ceramicization, thus reducing the heat transfer barrier performance. Comparative Example 2 does not incorporate reinforced aerogel; it directly uses unreinforced silica aerogel. During the mixing process, the microporous structure of the aerogel is damaged by compression, leading to an increase in thermal conductivity and a decrease in high-temperature thermal insulation effect.

[0047] It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and all such improvements and modifications fall within the scope of protection of this invention.

Claims

1. A method for preparing a ceramicized foamed silicone battery core heat insulation pad based on aerogel, characterized in that, Includes the following steps: S1. Reinforced aerogel powder: Carbon dioxide aerogel, liquid silicone rubber, and magnesium hydroxide whiskers are dispersed at a mass ratio of 100:(10~15):(5~10) at a high speed of 1200~2000 rpm and gradually heated to 120℃. During dispersion, the liquid silicone rubber is adsorbed by the carbon dioxide aerogel and vulcanized and foamed in situ. The mixture is then cooled by a cyclone sieve. A 10~15wt% modified solution is prepared by dissolving a silane coupling agent in ethanol. The modified solution is added according to a mass ratio of 10:100 between the modified solution and the carbon dioxide aerogel. The mixture is stirred at 60~80℃ for 15~30 min and dried to obtain reinforced aerogel powder. S2. Preparation of compound A: Add 100 parts by weight of methyl vinyl silicone rubber, 40-50 parts by weight of aluminum hydroxide, 20-30 parts by weight of low melting point glass powder, and 5-10 parts by weight of mica powder to a kneader and knead for 15-25 minutes; then add 20-25 parts by weight of reinforcing aerogel powder, 5-6 parts by weight of foaming agent, and 1-3 parts by weight of crosslinking agent and knead for 5-10 minutes to obtain compound A. S3. Preparation of compound B: According to the weight parts, add 100 parts of methyl vinyl silicone rubber, 10-15 parts of hydroxyl silicone oil, 40-50 parts of aluminum hydroxide, 20-30 parts of low melting point glass powder, and 5-10 parts of mica powder to a kneader and knead for 15-25 minutes; then add 5-10 parts of reinforcing aerogel powder, 8-10 parts of foaming agent, and 1-3 parts of crosslinking agent and knead for 5-10 minutes to obtain compound B. S4. Calendering and laminating: Compound A and compound B are calendered into sheets by calendering machines. The sheets are laminated in three layers of ABA with a thickness ratio of 1:3:1 and stored in a louvered cart. S5. Foaming and vulcanization: The composite from step S4 is placed into a molding die and vulcanized and foamed at 160~180℃ for 10~20 minutes. After shaping and cooling, it is die-cut to obtain a ceramicized foamed silicone battery core heat insulation pad based on aerogel.

2. The method for preparing an aerogel-based ceramicized foamed silicone battery core heat insulation pad according to claim 1, characterized in that, The silica aerogel powder has a particle size of 50~100μm and a pore size of 20~50nm.

3. The method for preparing an aerogel-based ceramicized foamed silicone battery core heat insulation pad according to claim 1, characterized in that, The liquid silicone rubber has the following weight formula: 100 parts vinyl silicone oil, 8 parts hydroxyl silicone oil, 10 parts hydrogen-containing silicone oil, 0.2 parts platinum catalyst, and 5-10 parts diluent.

4. The method for preparing an aerogel-based ceramicized foamed silicone battery core heat insulation pad according to claim 3, characterized in that, The platinum catalyst is a castor platinum catalyst with a concentration of 1000-10000 ppm; the diluent is ethanol or methanol.

5. The method for preparing an aerogel-based ceramicized foamed silicone battery cell heat insulation pad according to claim 1, characterized in that, The magnesium hydroxide whiskers have a diameter of 0.1-4.0 μm and a length of 5-50 μm.

6. The method for preparing an aerogel-based ceramicized foamed silicone battery cell heat insulation pad according to claim 1, characterized in that, The silane coupling agent is selected from at least one of KH-550, KH-560, and KH-570.

7. The method for preparing an aerogel-based ceramicized foamed silicone battery cell heat insulation pad according to claim 1, characterized in that, The methyl vinyl silicone rubber is a vinyl-terminated methyl vinyl silicone rubber raw rubber with a relative viscosity-average molecular weight of 400,000 to 600,000 and an ethylene molar content of 0.13 to 0.18%.

8. The method for preparing a ceramicized foamed silicone battery core heat insulation pad based on aerogel according to claim 1, characterized in that, The low-melting-point glass powder has a particle size of 5~10µm and an initial melting point of 500~600℃.

9. The method for preparing an aerogel-based ceramicized foamed silicone battery core heat insulation pad according to claim 1, characterized in that, The foaming agent is at least one of azodicarbonamide and 4,4'-oxobisbenzenesulfonylhydrazine; the crosslinking agent is at least one of DCP, DHBP, and BPO.

10. The aerogel-based ceramicized foamed silicone battery core heat insulation pad prepared by any one of the preparation methods of claims 1 to 9.

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