High-thermal-conductivity flame-retardant organic silicon pouring sealant for power battery module as well as preparation method and application of high-thermal-conductivity flame-retardant organic silicon pouring sealant
By designing composite thermally conductive fillers and synergistic flame retardants, a high thermal conductivity and flame retardant silicone potting compound was prepared, which solved the problems of insufficient thermal conductivity, flame retardancy and flexibility of existing potting compound materials, and improved the thermal management and safety of power battery packs.
Patent Information
- Application Number
- CN202511803147.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-03
- Publication Date
- 2026-02-24
AI Technical Summary
Existing potting compound materials have shortcomings in terms of thermal conductivity, flame retardancy, flexibility, and processability, making it difficult to meet the requirements of high energy density, safety, and cycle life of power battery packs.
A high thermal conductivity and flame retardant silicone potting compound was prepared by using a composite thermally conductive filler and synergistic flame retardant design. This was achieved by surface-modifying a mixture of spherical alumina and flake boron nitride, combined with the synergistic flame retardant mechanism of red phosphorus and platinum compounds.
It achieves high thermal conductivity (2.0-2.5 W/m·K), high flame retardancy (UL-94 V-0 rating), low stress, and good processability, thus improving the thermal management and safety performance of the battery module.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of power battery technology, specifically to a potting compound material for use inside power battery packs in electric vehicles, energy storage systems, etc., and in particular to an organosilicon composite material with high thermal conductivity, excellent flame retardancy, low density and the ability to adapt to changes in battery volume during charging and discharging, as well as the preparation method of the same, and the battery module structure using the potting compound.
[0002] With the rapid development of new energy vehicles, higher requirements have been placed on the energy density, safety, and cycle life of power batteries. During charging and discharging, battery cells generate a large amount of heat. If this heat cannot be dissipated in time, it can lead to uneven battery pack temperature, performance degradation, and even thermal runaway. At the same time, vibrations and impacts during vehicle operation also threaten the structural integrity of the battery.
[0003] Encapsulating compound is a key material used to fill the spaces between battery cells and inside modules. Its main function is: 1. Thermal management: Conducting the heat generated by the battery cell to the cooling system (such as cold plate, side plate).
[0004] 2. Structural support: Fixes the battery cells, prevents relative displacement, and resists vibration and impact.
[0005] 3. Electrical insulation: to prevent short circuits caused by leakage, condensation, etc.
[0006] 4. Flame retardant: Delays or inhibits the spread of fire during thermal runaway.
[0007] Currently, the most common potting compounds on the market are mainly divided into three categories: epoxy resin, polyurethane, and silicone. However, each of them has its own disadvantages: Epoxy resin: has a moderate thermal conductivity (~0.5 W / m·K), high hardness, and high brittleness. Under the volume changes of battery charging and discharging (such as the expansion of silicon-carbon anodes up to 10%), internal stress will be generated, leading to interface peeling or cell deformation.
[0008] Polyurethane: It has good toughness, but poor heat resistance (usually <120℃), poor flame retardancy, and may degrade and produce gas when exposed to water or high temperature, affecting the sealing performance.
[0009] Organosilicon: It is resistant to high and low temperatures (-50℃~200℃), has excellent electrical properties and good flexibility, but its thermal conductivity is low (~0.2 W / m·K). Flame retardancy requires the addition of a large amount of filler, which often leads to a sharp increase in viscosity, poor processability, and low mechanical strength.
[0010] Therefore, developing an organosilicon potting compound that can balance high thermal conductivity, high flame retardancy, low stress, and good processability is of great significance for improving the energy density, safety, and cycle life of power battery packs. Summary of the Invention
[0011] The purpose of this invention is to overcome the shortcomings of existing polyurethane and ordinary silicone potting compounds and provide a high thermal conductivity and flame retardant silicone potting compound for power battery modules with excellent overall performance. This potting compound achieves a breakthrough in performance through a unique composite thermally conductive filler and synergistic flame retardant design.
[0012] This invention is achieved through the following technical solution: A high thermal conductivity and flame retardant silicone potting compound for power battery modules, characterized in that it comprises: Component A and Component B are used in a mass ratio of 1:1. Component A is composed of the following raw materials in parts by weight: 100 parts of vinyl-terminated polydimethylsiloxane, 140-180 parts of composite thermally conductive filler, 8-12 parts of synergistic flame retardant, 5-10 parts of crosslinking agent, and 0.05-0.1 parts of inhibitor. Component B is composed of the following raw materials in parts by weight: 100 parts of vinyl-terminated polydimethylsiloxane, 140-180 parts of composite thermally conductive filler, 8-12 parts of synergistic flame retardant, and 0.8-1.5 parts of platinum catalyst. The composite thermally conductive filler is composed of spherical alumina with a surface modified by a silane coupling agent and plate-shaped boron nitride in a mass ratio of (4~5):1. In the composite thermally conductive filler, the particle size D50 of the spherical alumina is 1-3 μm; the particle size of the plate-shaped boron nitride is 10-15 μm, and the thickness is 0.5-2 μm. The synergistic flame retardant is a compound of surface-coated red phosphorus and platinum compound in a mass ratio of (7~8):1.
[0013] Preferably, the coating layer of the surface-coated red phosphorus is a composite coating layer of magnesium hydroxide and melamine resin, with a coating rate of ≥88%; the platinum compound is an isopropanol solution of chloroplatinic acid, with a platinum content of 3000-5000 ppm.
[0014] Preferably, the vinyl-terminated polydimethylsiloxane has a viscosity of 3000-5000 mPa·s at 25°C and a vinyl content of 0.8-1.2%. The crosslinking agent is a hydrogen-containing silicone oil with a hydrogen content of 0.8%-1.2%; The inhibitor is ethynylcyclohexanol; This invention also provides a method for preparing a high thermal conductivity and flame retardant silicone potting compound for power battery modules, comprising the following steps: (1) Pretreatment of composite thermally conductive filler: The mixture of spherical alumina and plate boron nitride was coupled with silane coupling agent; (2) Preparation of component A: In a planetary mixer, add vinyl-terminated polydimethylsiloxane for component A. Under a vacuum of <-0.095MPa, add the composite thermally conductive filler and synergistic flame retardant prepared in step (1) in sequence, and stir and mix for 60-90 minutes until uniform. Cool down to below 40℃, add crosslinking agent and inhibitor, stir and mix evenly, grind with a three-roll mill, degas under vacuum, and discharge for later use. (3) Preparation of component B: In a planetary mixer, add vinyl-terminated polydimethylsiloxane for component B. Under a vacuum of <-0.095MPa, add the composite thermally conductive filler and synergistic flame retardant prepared in step (1) in sequence, and stir and mix for 60-90 minutes until uniform. Cool down to below 40℃, add platinum catalyst, stir and mix evenly, grind with a three-roll mill, degas under vacuum, and discharge for later use. (4) When using, mix component A and component B evenly at a mass ratio of 1:1, and then perform the filling operation.
[0015] The specific steps for the pretreatment of the composite thermally conductive filler are as follows: spherical alumina and flake boron nitride are added to a high-speed mixer in a certain proportion, stirred and heated to 80-90°C, a silane coupling agent accounting for 1.0-1.5% of the total mass of the filler is sprayed, and after continuous reaction for 1-2 hours, the mixture is cooled and discharged for later use.
[0016] The present invention also provides a power battery module using the aforementioned high thermal conductivity and flame retardant silicone potting compound, comprising multiple parallel-arranged battery cells, end plates, side plates, and a liquid cooling system. The gaps between the battery cells and between the battery cells and the end plates and side plates are filled with an elastic thermally conductive material formed after the potting compound has cured. The side plates have built-in liquid cooling pipes, and the elastic thermally conductive material thermally couples the battery cells with the liquid cooling pipes.
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Ultra-high thermal conductivity: By compounding thermally conductive fillers of different shapes (spherical and sheet-like) and sizes, and performing surface modification treatment, a highly efficient three-dimensional thermally conductive network is constructed in the matrix. This composite filler system maintains good flowability even at a filling content of up to 65%, enabling the thermal conductivity of the potting compound to reach 2.0-2.5 W / m·K.
[0018] 2. Highly efficient synergistic flame retardancy: The innovative flame retardant system combines the gas-phase flame retardant mechanism of red phosphorus (generating PO· free radicals to quench the flame) and the condensed-phase char formation catalytic effect of platinum compounds (promoting the cross-linking of organosilicon to form SiO2 and SiC protective layers), achieving gas-phase-condensed-phase synergistic flame retardancy. It can achieve the UL-94 V-0 rating with a relatively low addition amount and a limiting oxygen index (LOI) > 45%.
[0019] 3. Excellent comprehensive performance: The cured colloid has low hardness (Shore A 30-40) and high elongation at break (>150%), effectively absorbing the volume change stress during the charging and discharging process of the battery cell and avoiding interfacial delamination. At the same time, it maintains the excellent electrical insulation properties of silicone materials (volume resistivity >1×10¹). 5 (Ω·cm) and aging resistance.
[0020] 4. Good processability: The viscosity of components A and B is matched, and the viscosity after mixing is moderate (8000-12000 mPa·s). The working time is long (>60min at 25℃), which is suitable for vacuum potting and there is no sedimentation or stratification. Detailed Implementation
[0021] The present invention will now be described in detail with reference to the embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention. Example
[0022] Preparation of Component A: In a planetary mixer, add 100 parts of vinyl-terminated polydimethylsiloxane AK 10000 (WACKER). Under a vacuum of -0.098 MPa, add 150 parts of composite thermally conductive filler (including 120 parts of spherical alumina FB-3SD (Denka) with surface treated with KH-570 silane coupling agent and 30 parts of plate-shaped boron nitride PolarTherm® 100 (Saint-Gobain)) and 10 parts of synergistic flame retardant (including 8.75 parts of red phosphorus RINKA® F-5 (Nippon Phosphate Chemical Industry) and 1.25 parts of platinum catalyst). Mix for 80 minutes until homogeneous. Cool to 35°C, add 7 parts of hydrogen-containing silicone oil HMS-301 (Momentive) and 0.08 parts of ethynylcyclohexanol. Mix thoroughly, grind twice with a three-roll mill, degas under vacuum, and discharge to obtain Component A.
[0023] Preparation of Component B: In a planetary mixer, add 100 parts of vinyl-terminated polydimethylsiloxane AK 10000 (WACKER). Under a vacuum of -0.098 MPa, add 150 parts of composite thermally conductive filler (same ratio as Component A) and 10 parts of synergistic flame retardant (same ratio as Component A), and mix for 80 minutes until homogeneous. Cool to 35°C, add 1.2 parts of platinum catalyst with a platinum content of 5000 ppm, mix thoroughly, and then grind twice using a three-roll mill. After vacuum degassing, discharge to obtain Component B. Example
[0024] Preparation of Component A: In a planetary mixer, add 100 parts of vinyl-terminated polydimethylsiloxane BLUESIL™ FLD46V (Elkem). Under a vacuum of -0.097 MPa, add 160 parts of composite thermally conductive filler (including 128 parts of spherical alumina FB-3SD (Denka) with surface treated with KH-570 silane coupling agent and 32 parts of plate-shaped boron nitride PolarTherm® 100 (Saint-Gobain)) and 9 parts of synergistic flame retardant (including 7.88 parts of red phosphorus RINKA® F-5 (Nippon Phosphate Chemical Industry) and 1.12 parts of platinum catalyst). Mix for 75 minutes until homogeneous. Cool to 38°C, add 8 parts of hydrogen-containing silicone oil HMS-301 (Momentive) and 0.06 parts of ethynylcyclohexanol. Mix thoroughly, then perform three-roll milling, vacuum degassing, and discharge to obtain Component A.
[0025] Preparation of Component B: In a planetary mixer, add 100 parts of vinyl-terminated polydimethylsiloxane BLUESIL™ FLD46V (Elkem), and under a vacuum of -0.097 MPa, add 160 parts of composite thermally conductive filler (same ratio as Component A) and 9 parts of synergistic flame retardant (same ratio as Component A). Mix for 75 minutes until homogeneous. Cool to 38°C, add 1.0 part of platinum catalyst, mix thoroughly, and then perform a three-roll milling process followed by vacuum degassing to obtain Component B. Example
[0026] Preparation of Component A: In a planetary mixer, add 100 parts of vinyl-terminated polydimethylsiloxane AK 10000 (WACKER). Under a vacuum of -0.099 MPa, add 170 parts of composite thermally conductive filler (including 136 parts of spherical alumina BHT-001 (Anhui Yishitong) with surface treated with KH-570 silane coupling agent and 34 parts of plate-shaped boron nitride SHP-10 (Denka)) and 11 parts of synergistic flame retardant (including 9.63 parts of red phosphorus RINKA® F-5 (Nippon Phosphate Chemical Industry) and 1.37 parts of platinum catalyst). Mix for 90 minutes until homogeneous. Cool to 33°C, add 6.5 parts of hydrogen-containing silicone oil HMS-301 (Momentive) and 0.09 parts of ethynylcyclohexanol. Mix thoroughly, then perform three-roll milling, vacuum degassing, and discharge to obtain Component A.
[0027] Preparation of Component B: In a planetary mixer, add 100 parts of vinyl-terminated polydimethylsiloxane AK 10000 (WACKER). Under a vacuum of -0.099 MPa, add 170 parts of composite thermally conductive filler (same ratio as Component A) and 11 parts of synergistic flame retardant (same ratio as Component A), and mix for 90 minutes until homogeneous. Cool to 33°C, add 1.4 parts of platinum catalyst, mix thoroughly, and then perform vacuum degassing after three-roll milling to obtain Component B. Example
[0028] Preparation of Component A: In a planetary mixer, add 100 parts of vinyl-terminated polydimethylsiloxane BLUESIL™ FLD46V (Elkem). Under a vacuum of -0.096 MPa, add 180 parts of composite thermally conductive filler (including 144 parts of spherical alumina BHT-001 (Anhui Yishitong) with surface treated with KH-570 silane coupling agent and 36 parts of sheet-like boron nitride SHP-10 (Denka)) and 8.5 parts of synergistic flame retardant (including 7.44 parts of red phosphorus RINKA® F-5 (Japan Phosphate Chemical Industry) and 1.06 parts of platinum catalyst). Mix for 85 minutes until homogeneous. Cool to 40°C, add 9 parts of hydrogen-containing silicone oil HMS-301 (Momentive) and 0.07 parts of ethynylcyclohexanol. Mix thoroughly, then perform three-roll milling, vacuum degassing, and discharge to obtain Component A.
[0029] Preparation of Component B: In a planetary mixer, add 100 parts of vinyl-terminated polydimethylsiloxane BLUESIL™ FLD46V (Elkem), and under a vacuum of -0.096 MPa, add 180 parts of composite thermally conductive filler (same ratio as Component A) and 8.5 parts of synergistic flame retardant (same ratio as Component A), and mix for 85 minutes until homogeneous. Cool to 40°C, add 0.9 parts of platinum catalyst, mix thoroughly, and after three-roll milling, degas under vacuum to obtain Component B.
[0030] Comparative Example 1 The preparation method is exactly the same as in Example 4, except that 180 parts of the composite thermally conductive filler are replaced with an equal amount of spherical alumina BHT-001 (Anhui Yishitong) treated with KH-570 silane coupling agent. That is, 180 parts of spherical alumina are used in each of components A and B, without any plate-like boron nitride.
[0031] Comparative Example 2 The preparation method is exactly the same as in Example 4, except that all 180 parts of the composite thermally conductive filler are replaced with an equal amount of surface-treated plate boron nitride SHP-10 (Denka) with KH-570 silane coupling agent. That is, 180 parts of plate boron nitride are used in each of components A and B, without spherical alumina.
[0032] Comparative Example 3 The preparation method is exactly the same as in Example 4, except that 8.5 parts of the synergistic flame retardant are replaced with an equal amount of coated red phosphorus RINKA® F-5 (Nippon Phosphorus Chemical Industry). That is, no platinum catalyst is added.
[0033] Comparative Example 4 The preparation method is similar to that of Example 4, except that the ratio of the composite thermally conductive filler is adjusted. The mass ratio of spherical alumina to plate-shaped boron nitride is adjusted to 2:1 (i.e., 120 parts alumina and 60 parts boron nitride), while the total number of parts remains 180. This ratio exceeds the range of (4~5):1 recommended by this invention.
[0034] Comparative Example 5 The preparation method is similar to that of Example 4, except that the ratio of the synergistic flame retardant is adjusted. The mass ratio of coated red phosphorus to platinum catalyst is adjusted to 10:1 (i.e., approximately 7.73 parts of coated red phosphorus and approximately 0.77 parts of platinum catalyst), while the total number of parts remains 8.5 parts. This ratio exceeds the recommended range of (7~8):1 of this invention.
[0035] Performance testing The components A and B prepared in the above embodiments were mixed evenly at a mass ratio of 1:1, and their performance was tested as follows: ,
[0036] The test data above shows that... 1. The composite thermally conductive filler has a significant synergistic enhancement effect: neither alumina (Comparative Example 1, 1.65 W / m·K) nor boron nitride (Comparative Example 2, 1.80 W / m·K) alone can achieve the thermal conductivity of the composite filler of the present invention (Example 4, 2.45 W / m·K).
[0037] 2. The filler compounding ratio is crucial and directly affects processability: excessive use of flake boron nitride (comparative examples 2 and 4) will lead to a sharp increase in viscosity, a shortened operating time, and deterioration of processability. The (4~5):1 ratio determined in this invention is the key to ensuring both high thermal conductivity and good processability.
[0038] 3. Synergistic flame retardants are key to achieving the highest flame retardant rating (V-0): using only coated red phosphorus (Comparative Example 3) or insufficient platinum catalyst (Comparative Example 5) can only achieve a secondary V-1 flame retardant rating.
[0039] 4. There is an irreplaceable synergistic effect between red phosphorus (gas phase flame retardant) and platinum catalyst (condensed phase char formation), and neither can be omitted, thus achieving ultimate safety with a low addition amount.
[0040] The high thermal conductivity and flame retardant silicone potting compound for power battery modules of this invention has extremely high thermal conductivity (≥2.15 W / m·K), excellent flame retardant properties (both reaching UL94 V-0 rating), moderate mixing viscosity, and good workability. After curing, the compound has low hardness and good flexibility, effectively absorbing stress, while also exhibiting good adhesion to metal substrates. Its comprehensive performance fully meets the stringent requirements of power battery modules for potting materials with high thermal conductivity, high safety, and low stress.
[0041] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.
Claims
1. A high thermal conductivity and flame retardant silicone potting compound for power battery modules, characterized in that, include: Component A and Component B are used in a mass ratio of 1:
1. Component A is composed of the following raw materials in parts by weight: 100 parts of vinyl-terminated polydimethylsiloxane, 140-180 parts of composite thermally conductive filler, 8-12 parts of synergistic flame retardant, 5-10 parts of crosslinking agent, and 0.05-0.1 parts of inhibitor. Component B is composed of the following raw materials in parts by weight: 100 parts of vinyl-terminated polydimethylsiloxane, 140-180 parts of composite thermally conductive filler, 8-12 parts of synergistic flame retardant, and 0.8-1.5 parts of platinum catalyst. The composite thermally conductive filler is composed of spherical alumina with a surface modified by a silane coupling agent and plate-shaped boron nitride in a mass ratio of (4~5):
1. The synergistic flame retardant is a compound of surface-coated red phosphorus and platinum compound in a mass ratio of (7~8):
1.
2. The high thermal conductivity and flame retardant silicone potting compound for power battery modules according to claim 1, characterized in that, In components A and B, the vinyl-terminated polydimethylsiloxane has a viscosity of 3000-5000 mPa·s at 25°C and a vinyl content of 0.8-1.2%.
3. The high thermal conductivity and flame retardant silicone potting compound for power battery modules according to claim 1, characterized in that, In the composite thermally conductive filler, the particle size D50 of the spherical alumina is 1-3 μm; the particle size of the plate-shaped boron nitride is 10-15 μm, and the thickness is 0.5-2 μm.
4. The high thermal conductivity and flame retardant silicone potting compound for power battery modules according to claim 1, characterized in that, In the synergistic flame retardant, the coating layer of the surface-coated red phosphorus is a composite coating layer of magnesium hydroxide and melamine resin, with a coating rate of ≥88%; the platinum compound is an isopropanol solution of chloroplatinic acid, with a platinum content of 3000-5000 ppm.
5. The high thermal conductivity and flame retardant silicone potting compound for power battery modules according to claim 1, characterized in that, In component A, the crosslinking agent is hydrogen-containing silicone oil with a hydrogen content of 0.8%-1.2%; the inhibitor is ethynylcyclohexanol.
6. A method for preparing a high thermal conductivity and flame retardant silicone potting compound for a power battery module according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Pretreatment of composite thermally conductive filler: The mixture of spherical alumina and plate boron nitride was coupled with silane coupling agent; (2) Preparation of component A: In a planetary mixer, add vinyl-terminated polydimethylsiloxane for component A. Under a vacuum of <-0.095MPa, add the composite thermally conductive filler and synergistic flame retardant prepared in step (1) in sequence, and stir and mix for 60-90 minutes until uniform. Cool down to below 40℃, add crosslinking agent and inhibitor, stir and mix evenly, grind with a three-roll mill, degas under vacuum, and discharge for later use. (3) Preparation of component B: In a planetary mixer, add vinyl-terminated polydimethylsiloxane for component B. Under a vacuum of <-0.095MPa, add the composite thermally conductive filler and synergistic flame retardant prepared in step (1) in sequence, and stir and mix for 60-90 minutes until uniform. Cool down to below 40℃, add platinum catalyst, stir and mix evenly, grind with a three-roll mill, degas under vacuum, and discharge for later use. (4) When using, mix component A and component B evenly at a mass ratio of 1:1, and then perform the filling operation.
7. The preparation method of the high thermal conductivity and flame retardant organosilicon potting compound for power battery modules according to claim 6, characterized in that, Pretreatment of the composite thermally conductive filler: Spherical alumina and flake boron nitride are added to a high-speed mixer in proportion, stirred and heated to 80-90℃, and 1.0-1.5% of silane coupling agent by weight of the filler is sprayed. After reacting for 1-2 hours, the mixture is cooled and discharged for later use.
8. A power battery module using the high thermal conductivity and flame retardant silicone potting compound according to any one of claims 1-5, characterized in that, It includes multiple parallel-arranged battery cells, end plates, side plates, and a liquid cooling system. The gaps between the battery cells and between the battery cells and the end plates and side plates are filled with an elastic thermally conductive body formed by the curing of the potting compound. The side plates have built-in liquid cooling pipes, and the elastic thermally conductive body thermally couples the battery cells with the liquid cooling pipes.