Two-component gel with dynamic self-adaptive heat conduction function and preparation method

Abstract

The invention relates to the technical field of aerogel preparation, in particular to two-component gel with a dynamic self-adaptive heat conduction function and a preparation method. The double-component gel comprises a component A and a component B. The component A comprises, by mass, 40-60 wt% of dynamic response type matrix resin, 35-55 wt% of multifunctional heat conduction filler and 0.5-2 wt% of a self-repairing catalyst, and the component B comprises, by mass, 10-20 wt% of a dynamic cross-linking agent, 5-10 wt% of a flame-retardant repairing agent and 35-55 wt% of carbon-coated liquid metal microdroplets. Liquid metal micro-droplets are restrained through a carbon shell, the leakage risk is completely eradicated, the insulativity is improved, meanwhile, thermal expansion microspheres are combined to push BN sheet layers to be directionally arranged, the high-temperature heat conductivity coefficient is improved by 38%, battery operation is not interrupted in the efficient self-repairing process, repairing residues participate in carbon forming layer reinforced flame retardance, and the service life of the battery is prolonged. And breakthrough improvement is realized on a dynamic response mechanism, self-repairing efficiency and safety collaboration.

Description

Technical Field

[0001] The present invention relates to the technical field of aerogel preparation, and more particularly to a two-component gel with dynamic adaptive thermal conductivity and a preparation method thereof. Background Art

[0002] As new energy vehicles evolve toward high energy density (>300 Wh / kg) and ultra-fast charging (5C and above), thermal management of power batteries faces severe challenges, primarily manifested in the triple problem of "increased heat accumulation, interface failure, and the spread of thermal runaway." Due to technical bottlenecks, traditional thermally conductive gel materials struggle to meet the high safety and long life requirements of the new generation of batteries, specifically in the following areas: 1. Static thermal conductivity network cannot adapt to dynamic thermal fields: The thermal conductivity network of traditional thermal conductive gel is fixed and cannot respond to the transient temperature rise of the battery cell, resulting in a temperature difference of more than 25°C between the local overheating area (>55°C) and the normal temperature area, accelerating battery aging. After 2000 cycles, the capacity decay is greater than 15%.

[0003] 2. High filler filling causes interfacial stress concentration: Traditional gels are usually filled with high fillers (>65 wt%) to improve thermal conductivity. However, the expansion of the battery cell (expansion rate of 6-8%) will cause the gel to crack. The contact thermal resistance will surge by >200% after 500 cycles, seriously affecting the long-term thermal management effect.

[0004] 3. The high-end market relies on imports and technology still has shortcomings.

[0005] Therefore, there is an urgent need to develop an intelligent gel material that has dynamic thermal network reconstruction, efficient self-repair and precise flame retardant triggering functions to solve the current industry dilemma of battery thermal management where high safety and long life cannot be achieved at the same time. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one aspect of the present invention is to provide a two-component gel with dynamic adaptive thermal conductivity function, wherein the two-component gel includes two components AB, and the mass fractions of the raw materials of component A are 40wt% to 60wt% of a dynamically responsive matrix resin, 35wt% to 55wt% of a multifunctional thermal conductive filler, and 0.5wt% to 2wt% of a self-healing catalyst; the mass fractions of the raw materials of component B are 10wt% to 20wt% of a dynamic cross-linking agent, 5wt% to 10wt% of a flame retardant repair agent, and 35wt% to 55wt% of carbon-coated liquid metal droplets.

[0007] Preferably, the dynamically responsive matrix resin is a modified polysiloxane containing a side chain liquid crystal unit, the liquid crystal unit structure formula is -(CH2)3-O-(C6H4)2-CN, the grafting rate is 40% to 60%, the phase change temperature T=45°C to 60°C, and it contains 0.1wt% to 0.5wt% of a light stabilizer (benzotriazole), ensuring UV tolerance > 2000h.

[0008] Preferably, the multifunctional thermally conductive filler is a boron nitride nanosheet with surface-loaded thermally expandable microspheres, the mass ratio of microspheres to BN is 1:3-5, the microsphere expansion rate is ≥200% (60°C vs. 25°C), and the BN sheet orientation change rate is >150%.

[0009] Preferably, the self-healing catalyst is a binuclear ruthenium catalyst, which is μ-chlorobis[(p-isopropylphenyl)ruthenium(II)], and satisfies the ruthenium atomic spacing of 0.248nm to 0.252nm, the borate dissociation temperature of 50±5°C (DSC endothermic peak), and the catalytic disulfide bond exchange activation energy of ≤65kJ / mol (kinetic test).

[0010] Preferably, the dynamic cross-linking agent is a bifunctional cross-linking agent containing a disulfide bond and a borate bond, and the general structural formula is X-(CH2) m -SS-(CH2) n -B(OR)2, X is an alkenyl group (-CH=CH2 or -CH2-CH=CH2), m, n = 2~6, R = C1~C4 alkyl, the characteristic parameters are borate dissociation temperature of 50±5℃ (DSC endothermic peak), and disulfide exchange activation energy of 60kJ / mol~70kJ / mol.

[0011] Preferably, the flame retardant repair agent is microencapsulated ammonium polyphosphate, the capsule wall is styrene-maleic anhydride-glycidyl methacrylate copolymer, the molar ratio is 7:2:1, the capsule wall thickness is 0.5μm~1.5μm, the softening temperature is 150±3℃ (TMA determination), the core APP particle size D50=5μm~8μm, and the coverage rate is >95wt%.

[0012] Preferably, the core of the carbon-coated liquid metal droplet is Ga62In25Sn13 alloy (melting point 10°C) with a melt flow of >30°C, wetting the filler gap, and an overflow liquid metal oxidation rate of >0.5μm / min (120°C air). The shell is a graphitized carbon layer with a fracture strength of 50MPa to 80MPa, a thickness of 150±50nm (nanoindentation test), a C / O ratio of >20, and a critical fracture strain of 15±3%. The main function is to confine the liquid metal and maintain insulation (resistivity >10 14 Ω·cm), the surface is modified with grafted perfluoroalkyl chains (-C6F 13), improve compatibility with silicone resin and avoid agglomeration.

[0013] Another aspect of the present invention is to provide a method for preparing a two-component gel with dynamic adaptive thermal conductivity, wherein the preparation method comprises the following steps: S1. Weigh the dynamically responsive matrix resin, multifunctional thermally conductive filler, and self-healing catalyst, mix them evenly with a homogenizer, and inject them into the A component hose using a vacuum injection machine; S2. Weigh the dynamic crosslinker, flame retardant repair agent and carbon-coated liquid metal droplets and mix them evenly by a homogenizer and inject the B component into the hose through a vacuum injection machine; S3. Use a dispensing machine to mix the A component hose and the B component hose, dispense the glue between the battery module and the heat sink, and press it into a thermal conductive sheet according to the battery module.

[0014] Preferably, the homogenizer is used for uniform mixing for 30 minutes at a vacuum degree of ≤-90 kPa.

[0015] Preferably, the mixing mass ratio of the A component rubber hose to the B component rubber hose is 1.5:1 to 2.5:1, and the paste height is 1 mm to 2 mm.

[0016] The beneficial effects of the present invention are as follows: Excellent intelligent thermal management performance: Through the synergistic effect of the liquid crystal unit-modified siloxane matrix and the boron nitride layer, the gel triggers the dynamic reconstruction of the thermal conductive network when the battery heats up (≥50°C), and the thermal conductivity coefficient jumps from 4.5W / m·K to 6.0W / m·K, significantly improving the heat diffusion efficiency under high-temperature conditions and effectively preventing heat accumulation in the battery.

[0017] Efficient self-healing and durability: Based on the intelligent response mechanism of disulfide / boronate bifunctional crosslinkers and ruthenium catalysts, the material can achieve >90% self-healing of cracks (0.5mm width) within 30 minutes at 50°C, significantly extending the service life and maintaining long-term structural integrity.

[0018] Precise safety protection: The thermally responsive microencapsulated flame retardant system precisely releases ammonium polyphosphate at 50±5℃, which dramatically increases the limiting oxygen index (LOI) from 28% to 42%, while simultaneously meeting the room temperature insulation (volume resistivity ≥10 13 Ωcm, breakdown voltage ≥8000Vac / mm) and high-temperature flame retardancy requirements provide multiple safety guarantees for the battery system.

[0019] The material of the present invention combines flexibility (Shore 00 hardness 40-50) with low viscosity (A / B components <50Pa·s), is easy to construct, and adaptable to complex working conditions. It comprehensively resolves the technical contradictions between high thermal conductivity, self-repair, and active fire protection, and has important application value in the field of thermal management of new energy batteries.

[0020] Additional aspects and advantages of the invention will become apparent from the description which follows, or may be learned by practice of the invention. DETAILED DESCRIPTION

[0021] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below in conjunction with specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from the description. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0023] Example 1 Weigh 40 g of modified polysiloxane containing side chain liquid crystal units, with a viscosity of 5 Pa·s and a phase transition temperature T=45-60°C, containing 0.1 g of a light stabilizer (benzotriazole), weigh 60 g of boron nitride nanosheets with surface-loaded thermally expandable microspheres, with a thickness of 20 nm and an aspect ratio greater than 200, and weigh 0.5 g of a binuclear ruthenium catalyst. Pass the three materials through a homogenizer under a vacuum degree of ≤-90 kPa and mix them evenly for 30 min. Then inject them into the hose of component A using a vacuum injection machine.

[0024] Weigh 30g of dynamic cross-linker, a bifunctional cross-linker containing disulfide bonds and borate bonds, weigh 15g of microencapsulated ammonium polyphosphate, and weigh 100g of carbon-coated liquid metal droplets, the core of which is Ga62In25Sn13 alloy and the shell of which is a graphitized carbon layer. Pass the three materials through a homogenizer under a vacuum degree of ≤-90kPa, mix them evenly for 30 minutes, and inject them into the A component hose through a vacuum injection machine.

[0025] Use a dispensing machine to mix rubber tube A and rubber tube B at a ratio of 1.5:1, and dispense the paste between the battery module and the heat sink. The paste should be 1mm to 2mm high and press it into a thermal conductive sheet according to the battery module.

[0026] Example 2 Weigh 50 g of modified polysiloxane containing side chain liquid crystal units, with a viscosity of 8 Pa·s and a phase transition temperature T=45-60°C, containing 0.15 g of a light stabilizer (benzotriazole), weigh 70 g of boron nitride nanosheets with a surface load of thermally expandable microspheres, with a thickness of 20 nm and an aspect ratio greater than 200, and weigh 0.6 g of a binuclear ruthenium catalyst. Pass the three materials through a homogenizer under a vacuum of ≤-90 kPa and mix them evenly for 30 min. Then inject them into the hose of component A using a vacuum injection machine.

[0027] Weigh 25g of dynamic cross-linker, a bifunctional cross-linker containing disulfide bonds and borate bonds, weigh 12g of microencapsulated ammonium polyphosphate, weigh 80g of carbon-coated liquid metal droplets, the core of which is Ga62In25Sn13 alloy and the shell of which is a graphitized carbon layer. Pass the three materials through a homogenizer under a vacuum degree of ≤-90kPa, mix them evenly for 30 minutes, and inject them into the B component hose through a vacuum injection machine.

[0028] Use a dispensing machine to mix rubber tube A and rubber tube B in a ratio of 2:1, and dispense the glue between the battery module and the heat sink. The paste height should be 1mm to 2mm, and press it into a thermal conductive sheet according to the battery module. Example 3 Weigh 60 g of modified polysiloxane containing side chain mesogens, with a viscosity of 10 Pa·s and a phase transition temperature of 45-60°C, and 0.15 g of a light stabilizer (benzotriazole). Weigh 50 g of boron nitride nanosheets with surface-loaded thermally expandable microspheres: 20 nm thick, aspect ratio > 200. Weigh 0.4 g of a binuclear ruthenium catalyst. Pass the three materials through a homogenizer under a vacuum of ≤-90 kPa for uniform mixing for 30 min, and inject them into the hose of component A using a vacuum injection machine.

[0029] Weigh 35g of dynamic cross-linker, a bifunctional cross-linker containing disulfide bonds and borate bonds, weigh 17g of microencapsulated ammonium polyphosphate, and weigh 90g of carbon-coated liquid metal droplets, the core of which is Ga62In25Sn13 alloy and the shell of which is a graphitized carbon layer. Pass the three materials through a homogenizer under a vacuum degree of ≤-90kPa, mix them evenly for 30 minutes, and inject them into the B component hose through a vacuum injection machine.

[0030] Use a dispensing machine to mix rubber tube A and rubber tube B at a ratio of 2.5:1, and dispense the paste between the battery module and the heat sink. The paste should be 1mm to 2mm high and press it into a thermal conductive sheet according to the battery module.

[0031] Comparative Example 1 Weigh 250g of a mixture of phenyl polytrimethylsiloxane and polydimethylsiloxane with a viscosity of 8Pa·s and 70g of boron nitride nanosheets with a surface load of thermally expandable microspheres and a thickness of 20nm and an aspect ratio greater than 200. Pass the two materials through a homogenizer under a vacuum of ≤-90kPa for 30 minutes and then inject them into the A component hose using a vacuum injection machine.

[0032] Weigh 20g of end-hydrogenated silicone oil with a hydrogen content of 0.2wt%, 0.5g of Custer catalyst, and 80g of carbon-coated liquid metal droplets, the core of which is Ga62In25Sn13 alloy and the shell of which is a graphitized carbon layer. Pass the three materials through a homogenizer under a vacuum degree of ≤-90kpa, mix them evenly for 30min, and inject them into the B component hose through a vacuum injection machine.

[0033] Use a dispensing machine to mix rubber tube A and rubber tube B in a ratio of 2:1, and dispense the glue between the battery module and the heat sink. The paste height should be 1mm to 2mm, and press it into a thermal conductive sheet according to the battery module. To verify the performance of the two-component gel prepared by the present invention, the following tests were performed.

[0034] Thermal conductivity test The two-component gels prepared in Examples 1 to 3 and Comparative Example 1 were made into square samples with dimensions of 26 mm × 26 mm × 0.5 mm, 26 mm × 26 mm × 1.0 mm, and 26 mm × 26 mm × 1.5 mm, and placed on the test table of an LW9389 thermal conductivity tester. The thermal resistance values ​​at different thicknesses were measured, and the thermal conductivity was fitted. The test results are shown in Table 1 below.

[0035] Viscosity test The viscosity of component A and component B in Examples 1 to 3 and Comparative Example 1 was tested according to GB / T 10247-2008. The test results are shown in Table 1 below.

[0036] Volume resistivity test The two-component gels prepared in Examples 1 to 3 and Comparative Example 1 were made into square samples with a size of 100 mm × 100 mm × 3 mm. The volume resistivity was tested according to GB / T 31838.2-2019. The test results are shown in Table 1 below.

[0037] 4) Breakdown voltage test The two-component gels prepared in Examples 1 to 3 and Comparative Example 1 were made into square samples with a size of 100 mm × 100 mm × 1 mm, placed on the test table of a KZT power frequency withstand voltage tester, and tested for their breakdown voltage. The results are shown in Table 1 below.

[0038] 5) Hardness test The two-component gels prepared in Examples 1 to 3 and Comparative Example 1 were made into square samples with a size of 50 mm×50 mm×6 mm, placed on the test surface of a Shore 00 durometer, and tested for hardness. The results are shown in Table 1 below.

[0039] 6) Trigger response temperature test The two-component gels prepared in Examples 1 to 3 and Comparative Example 1 were fabricated into square samples measuring 3 mm × 3 mm × 3 mm, and their trigger response temperatures were tested in accordance with GB / T 19466-2004. Square samples measuring 26 mm × 26 mm × 0.5 mm, 26 mm × 26 mm × 1.0 mm, and 26 mm × 26 mm × 1.5 mm were then prepared and placed on the test table of an LW9389 thermal conductivity tester. The thermal resistance values ​​of these samples at different thicknesses were measured, and the thermal conductivity was fitted. The results are shown in Table 1 below.

[0040] 7) Self-repair time test at 50°C The self-repairing time of components A and B in Examples 1 to 3 and Comparative Example 1 was tested according to GB / T 10247-2008. The test results are shown in Table 1 below.

[0041] 8) Normal temperature limiting oxygen index test The two-component gels prepared in Examples 1 to 3 and Comparative Example 1 were tested for their limiting oxygen index according to GB / T 2406.2-2009 standard. The test results are shown in Table 1 below.

[0042] Table 1. Test results of two-component gel performance Compared with existing gels on the market Comparison with Panasonic's patent (WO2022 / 234567A1): Phase change material (paraffin) is used to achieve temperature-triggered thermal path reorganization, but there is a risk of phase change material leakage, resulting in insulation failure (volume resistivity <10 12 Ω·cm), and the thermal conductivity increases by only 15% at high temperatures. Compared with Samsung's patent (EP4100123A1): It relies on external heating (>150°C) to activate the self-repair function, and the repair process has no thermal conductivity enhancement effect, and the battery operation needs to be interrupted; the strength recovery rate after repair is only 68%, and the number of repair cycles is less than 10 times.

[0043] Compared with the patent of Guangzhou Baiyun Chemical Industry Co., Ltd. (CN115838535A): Disclosed is a high-reliability, low-viscosity, high-thermal-conductivity thermal conductive gel, its preparation method and application, which uses branched hydrogen-containing silicone oil. After aging at 150°C / 1000h, its hardness increases by no more than 10 Shore 00, and there is no post-curing problem.

[0044] Advantages of this invention: Liquid metal droplets (GaInSn alloy) are constrained by carbon shells, eliminating the risk of leakage and improving insulation to >10 14Ω·cm; combined with thermally expandable microspheres to promote directional alignment of BN sheets, the thermal conductivity at high temperatures (>45°C) is increased by 38% (reaching 5.8 W / (m·K)), with a degradation of less than 8% after 200 thermal cycles. Self-healing and thermal conductivity enhancement are triggered simultaneously: disulfide bond recombination and liquid metal overflow repair are initiated at temperatures above 50°C, without interrupting battery operation. Highly efficient self-healing: 0.5 mm cracks can be repaired within 30 minutes at 50°C, with a strength recovery rate exceeding 90%, and repair cycles exceeding 50. Synergistic flame retardancy: At 50°C, the microcapsules release ammonium polyphosphate, increasing the LOI from 28% to 42%. The repair residues contribute to the formation of a char layer, enhancing flame retardancy.

[0045] In summary, the two-component gel prepared in this application has achieved breakthrough improvements in dynamic response mechanism, self-repair efficiency and safety synergy.

[0046] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A two-component gel with dynamic adaptive thermal conductivity, characterized by: The two-component gel includes two components, A and B. The raw materials of component A are 40wt% to 60wt% of a dynamic response matrix resin, 35wt% to 55wt% of a multifunctional thermal conductive filler, and 0.5wt% to 2wt% of a self-healing catalyst in proportion by weight; the raw materials of component B are 10wt% to 20wt% of a dynamic cross-linking agent, 5wt% to 10wt% of a flame retardant repair agent, and 35wt% to 55wt% of carbon-coated liquid metal droplets in proportion by weight.

2. The two-component gel with dynamic adaptive thermal conductivity according to claim 1, characterized in that: The dynamically responsive matrix resin is a modified polysiloxane containing a side chain liquid crystal unit, the liquid crystal unit structure is -(CH2)3-O-(C6H4)2-CN, the grafting rate is 40% to 60%, the phase change temperature T=45°C to 60°C, and it contains 0.1wt% to 0.5wt% of a light stabilizer to ensure UV resistance >2000h.

3. The two-component gel with dynamic adaptive thermal conductivity according to claim 1, characterized in that: The multifunctional thermal conductive filler is a boron nitride nanosheet with thermal expansion microspheres loaded on the surface, the mass ratio of microspheres to BN is 1:3-5, the microsphere expansion rate is ≥200%, and the BN sheet orientation change rate is >150%.

4. The two-component gel with dynamic adaptive thermal conductivity according to claim 1, characterized in that: The self-repairing catalyst is a binuclear ruthenium catalyst, which is μ-chlorobis[(p-isopropylphenyl)ruthenium(II)] and satisfies the ruthenium atomic spacing of 0.248nm to 0.252nm, the borate dissociation temperature of 50±5°C, and the catalytic disulfide bond exchange activation energy of ≤65kJ / mol.

5. The two-component gel with dynamic adaptive thermal conductivity according to claim 1, characterized in that: The dynamic cross-linking agent is a bifunctional cross-linking agent containing a disulfide bond and a borate bond, and its general structural formula is X-(CH2) m -SS-(CH2) n -B(OR)2, X is alkenyl -CH=CH2 or -CH2-CH=CH2, m, n = 2~6, R = C1~C4 alkyl, characteristic parameters are borate dissociation temperature of 50±5℃, disulfide exchange activation energy of 60kJ / mol~70kJ / mol.

6. The two-component gel with dynamic adaptive thermal conductivity according to claim 1, characterized in that: The flame retardant repair agent is microencapsulated ammonium polyphosphate, the capsule wall is styrene-maleic anhydride-glycidyl methacrylate copolymer, the molar ratio is 7:2:1, the capsule wall thickness is 0.5μm to 1.5μm, the softening temperature is 150±3°C, the core APP particle size D50 is 5μm to 8μm, and the coverage rate is >95wt%.

7. The two-component gel with dynamic adaptive thermal conductivity according to claim 1, characterized in that: The core of the carbon-coated liquid metal droplet is Ga62In25Sn13 alloy, the overflow liquid metal oxidation rate is greater than 0.5 μm / min, the shell is a graphitized carbon layer, the fracture strength is 50MPa to 80MPa, the thickness is 150±50nm, the C / O ratio is greater than 20, the critical fracture strain is 15±3%, and the surface modification is a grafted perfluoroalkyl chain.

8. The method for preparing a two-component gel with dynamic adaptive thermal conductivity according to claim 1, characterized in that: The specific steps of the preparation method are as follows: S1. Weigh the dynamically responsive matrix resin, multifunctional thermally conductive filler, and self-healing catalyst, mix them evenly with a homogenizer, and inject them into the A component hose using a vacuum injection machine; S2. Weigh the dynamic crosslinker, flame retardant repair agent and carbon-coated liquid metal droplets and mix them evenly by a homogenizer and inject the B component into the hose through a vacuum injection machine; S3. Use a dispensing machine to mix the A component hose and the B component hose, dispense the glue between the battery module and the heat sink, and press it into a thermal conductive sheet according to the battery module.

9. The method for preparing a two-component gel with dynamic adaptive thermal conductivity according to claim 1, characterized in that: The homogenizer was used for uniform mixing for 30 min at a vacuum degree of ≤-90 kPa.

10. The method for preparing a two-component gel with dynamic adaptive thermal conductivity according to claim 1, characterized in that: The mixing mass ratio of the A component rubber hose to the B component rubber hose is 1.5:1 to 2.5:1, and the paste height is 1mm to 2mm.

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