A battery pack heat insulation material and its preparation method

Abstract

The invention discloses a battery pack thermal insulation material, the raw materials of the battery pack thermal insulation material include vermiculite, perlite, aerogel precursor, composite anticorrosive agent, composite flexibilizer, and the ratio of the vermiculite, perlite, aerogel precursor, composite anticorrosive agent, and composite flexibilizer by mass is (3 parts-7 parts): (2 parts-8 parts): (2 parts-6 parts): (0.5 parts-1 parts): (1.5 parts-2 parts); the composite anticorrosive agent includes silane coupling agent modified aluminum silicate ceramic fiber and halogenated polyethylene; the composite flexibilizer includes dialkyl dimethyl quaternary ammonium salt, polyethyleneimine, and polysiloxane-polyether copolymer. The battery pack thermal insulation material obtained by the inventive method has the characteristics of low thermal conductivity and high temperature resistance, a wide range of product applications, a simple production process, and excellent thermal insulation performance.

Description

Technical Field

[0001] The present invention relates to the field of material technology, and in particular to a battery pack thermal insulation material and a preparation method thereof. Background Art

[0002] As the electric vehicle market continues to expand, power battery technology is also advancing. As the heart of an electric vehicle, the performance of the power battery is directly related to its range, safety, and stability. While ensuring battery performance, thermal insulation of the power battery pack has also become a critical issue.

[0003] The primary advantage of thermal insulation for power battery packs is that it improves the efficiency, safety, and stability of power batteries. First, the operating efficiency of power batteries is significantly affected by temperature; both high and low temperatures can affect battery performance. Thermal insulation materials can effectively maintain the appropriate operating temperature range for power batteries, thereby improving battery efficiency. Secondly, power battery safety is also a significant concern. Excessively high temperatures can easily cause battery explosions and fires, while thermal insulation materials can effectively reduce battery temperatures and provide insulation when the battery overheats. Finally, as electric vehicle speeds and driving time increase, battery heat is easily generated. Thermal insulation materials can help batteries maintain stable operation, thereby extending their service life.

[0004] The most common high-performance battery insulation sheet on the market is aerogel insulation sheet. It mainly uses the compression resilience of aerogel to compress the aerogel between two battery cells. When the battery is loose, it can generate squeezing force on the battery cells on both sides to prevent loosening, thereby ensuring that the working state of the battery is in a relatively stable state and protecting the normal operation of the battery. However, the surface material of the insulation sheet can withstand temperatures not exceeding 300°C (such as PET film will be damaged if it exceeds 150°C), and the temperature of the battery after spontaneous combustion can instantly reach over 800°C or even higher. When the surface layer of the insulation sheet is easily damaged, it will not only affect the normal operation of the battery, but also lead to a decrease in the safety performance of the battery. Therefore, a new material is needed that can not only ensure squeezing when the battery cell is loose, but also ensure good thermal insulation under high temperature conditions.

[0005] In existing thermal insulation materials, vermiculite and perlite help improve the material's high-temperature resistance, maintaining optimal performance at temperatures above 800°C. When expanded at high temperatures, vermiculite and perlite significantly increase their specific surface area and porosity, improving thermal stability and thermal insulation. However, in existing technologies, vermiculite and perlite are often used in thermal insulation coatings and other applications, rather than in battery pack insulation.

[0006] First, battery pack insulation materials need to be thin and lightweight to increase the volume ratio of the battery cells within the pack, thereby improving the pack's capacity. The key challenge is balancing thinness with thermal insulation performance. Second, during battery production, moisture is inevitably present in the electrolyte. During battery cycling, as the temperature rises, this moisture evaporates, and the perlite corrodes the metal due to the released water vapor. Third, the reaction between moisture and lithium salts produces corrosive gases, which can also corrode the insulation material. Summary of the Invention

[0007] In response to the problems in the prior art, the present invention discloses a battery pack insulation material and a preparation method thereof. The battery pack insulation material of the present invention not only has an anti-corrosion effect when used in batteries, but also has good heat preservation and insulation properties, which is beneficial to improving the electrical performance and safety of the battery.

[0008] The present invention is achieved through the following technical solutions:

[0009] The present invention provides a battery pack insulation material, the raw materials of which include vermiculite, perlite, an aerogel precursor, a composite anti-corrosion agent, and a composite flexibilizer. By mass, the ratio of the vermiculite, perlite, aerogel precursor, composite anti-corrosion agent, and composite flexibilizer is (3 parts-7 parts): (2 parts-8 parts): (2 parts-6 parts): (0.5 parts-1 part): (1.5 parts-2 parts); the composite anti-corrosion agent includes silane coupling agent-modified aluminum silicate ceramic fiber and halogenated polyethylene; the composite flexibilizer includes dialkyl dimethyl quaternary ammonium salt, polyethyleneimine, and polysiloxane-polyether copolymer.

[0010] According to the above design of the present invention, the silica aerogel formed by the aerogel precursor can not only promote the normal working state of the battery pack in the low temperature stage, but also the compression resilience of the aerogel can make the extrusion force of the battery cells in the battery pack more stable, thereby avoiding loosening between the battery cells. On this basis, vermiculite and perlite can exert their thermal insulation properties in the high temperature stage, which is beneficial to improving the safety performance of the battery pack; and with the combination of vermiculite and perlite, the battery pack insulation material can also form an adjustable expansion volume in the battery pack, which is beneficial to reduce the loosening between the battery cells when the battery pack works in a long cycle or at a high temperature. In addition, we have further designed a composite anti-corrosion agent. The halogenated polyethylene in the composite anti-corrosion agent is combined with the silane coupling agent modified aluminum silicate ceramic fiber to improve the corrosion resistance and waterproof performance of the battery pack insulation material, which can reduce the damage of the corrosive materials in the battery environment to the battery pack insulation material. In addition, the silane coupling agent-modified aluminum silicate ceramic fiber in the composite anti-corrosion agent is combined with vermiculite and perlite to improve the thermal insulation performance of the battery pack insulation material. On the other hand, the amount of vermiculite and perlite added to the battery pack insulation material can be further controlled, thereby balancing the relationship between the lightness and thermal insulation performance of the battery pack insulation material. In the present invention, we have further designed a composite flexibilizer that not only cooperates with each other to improve the flexibility of the insulation material, but also reduces the volume proportion of the insulation material in the battery pack, thereby facilitating an increase in the volume proportion of the battery cells in the battery pack, thereby increasing the energy density of the battery pack. Silane coupling agent-modified aluminum silicate ceramic fibers not only enhance the insulation's corrosion resistance to corrosive gases in battery packs, but also improve its strength, thereby balancing the flexibility imparted by the composite flexibilizer. Halogenated polyethylene not only reduces the brittleness of the silane coupling agent-modified aluminum silicate ceramic fibers, facilitating their structural stability within the insulation, but also enhances their flame retardancy and chemical resistance. To promote uniform mixing between the composite anticorrosive and flexibilizer compounds, we further formulated the silane coupling agent-modified aluminum silicate ceramic fibers with polysiloxane-polyether copolymers and the halogenated polyethylene with polyethyleneimine, resulting in a better synergistic effect between the composite anticorrosive and flexibilizer compounds. On this basis, the dialkyl dimethyl quaternary ammonium salt not only interacts with polyethyleneimine to reduce the flow of static charge during battery pack cycling, thereby improving the safety performance of the battery pack, but also reduces the viscosity of polyethyleneimine and polysiloxane-polyether copolymer in the composite flexibilizer, facilitating the coordination and dispersion of the substances. Furthermore, at the added mass ratio of this invention, the resulting thermal insulation material not only has improved flexibility, but also has better water resistance and corrosion resistance. Furthermore, the thermal insulation material of the present invention has a thinner volume and better thermal insulation performance.

[0011] As a further solution, the ratio of the silane coupling agent-modified aluminum silicate ceramic fiber to the halogenated polyethylene is (1.5 parts to 2 parts): (0.5 parts to 1 part) by mass. Adding more silane coupling agent-modified aluminum silicate ceramic fiber than halogenated polyethylene is necessary to not only balance the flexibility of the thermal insulation material but also improve the corrosion resistance of the thermal insulation material. Adding a small amount of halogenated polyethylene not only improves the corrosion resistance of the silane coupling agent-modified aluminum silicate ceramic fiber but also reduces its brittleness.

[0012] As a further embodiment, the ratio of the dialkyl dimethyl ammonium salt, polyethyleneimine, and polysiloxane-polyether copolymer is (0.5-1 part): (0.5-1 part): (2-3 parts) by mass. In the composite flexibilizer, the polysiloxane-polyether copolymer is primarily used to enhance the flexibility of the thermal insulation material, while the addition of a small amount of the dialkyl dimethyl ammonium salt and polyethyleneimine not only assists the polysiloxane-polyether copolymer in enhancing the flexibility of the thermal insulation material but also reduces the flow of static charge during battery pack cycling.

[0013] As a further embodiment, the silane coupling agent used to modify the aluminum silicate ceramic fiber includes one or more of KH550, KH560, KH570, KH792, and DL602. The aluminum silicate ceramic fiber modified with the silane coupling agent not only exhibits enhanced corrosion resistance but also improves the stability of the combination between the aluminum silicate ceramic fiber and the halogenated polyethylene.

[0014] As a further embodiment, the polyethyleneimine comprises SP-018.

[0015] As a further embodiment, the halogenated polyethylene includes one or more of polyvinyl fluoride and polyvinyl chloride. The halogenated substituents can also improve the flame retardancy and chemical resistance of the thermal insulation material.

[0016] As a further embodiment, the dialkyl dimethyl quaternary ammonium salt has the structural formula (1):

[0017]

[0018] Wherein, R1 and R2 are each methyl, A - One selected from bicarbonate and halogen ions.

[0019] As a further embodiment, each of R1 and R2 is a methyl group having a fluorine-substituted group.

[0020] As a further embodiment, each of R1 and R2 is a methyl group of a perfluorosubstituted group.

[0021] As a further embodiment, the polysiloxane in the polysiloxane-polyether copolymer includes polydimethylsiloxane.

[0022] As a further embodiment, the polyether copolymer in the polysiloxane-polyether copolymer includes acetylene glycol polyether. The polyether copolymer can improve the flexibility of polysiloxane.

[0023] As a further embodiment, the aerogel precursor includes silicate.

[0024] As a further embodiment, the silicate includes one or more of methyl orthosilicate and ethyl orthosilicate.

[0025] As a further solution, the raw materials of the battery pack thermal insulation material also include an inorganic adhesive, and the mass proportion of the inorganic adhesive in the raw materials is 7%-10%.

[0026] As a further solution, the inorganic adhesive includes alumina powder, aluminum silicate powder, and sodium silicate. By mass, the ratio of the alumina powder, aluminum silicate powder, and sodium silicate is (10 parts-50 parts): (10 parts-50 parts): (30 parts-90 parts).

[0027] As a further solution, the D50 of the alumina powder and the aluminum silicate powder is 30 μm-70 μm.

[0028] As a further solution, the raw materials of the battery pack thermal insulation material also include a modifier.

[0029] As a further solution, the modifier includes a hexamethyldisilazane solution, and the concentration of the hexamethyldisilazane solution is 2%-8%.

[0030] As a further embodiment, the solvent of the hexamethyldisilazane solution is ethanol.

[0031] As a further solution, the thickness of the battery pack insulation material is 2mm-4mm.

[0032] As a further solution, the thermal conductivity of the battery pack insulation material is 0.015 W·m -1 ·K -1 -0.03W·m -1 ·K -1 .

[0033] As a further solution, the raw materials of the battery pack insulation material include vermiculite, perlite, aerogel precursor, composite anticorrosive agent, and composite flexibilizer. The ratio of the vermiculite, perlite, aerogel precursor, composite anticorrosive agent, and composite flexibilizer by mass is (4 parts-6 parts): (4 parts-6 parts): (2 parts-6 parts): (0.7 parts-0.9 parts): (1.6 parts-1.8 parts); the composite anticorrosive agent includes silane coupling agent modified aluminum silicate ceramic fiber and polyvinyl fluoride; the composite flexibilizer includes R1 and R2 as perfluorosubstituted methyl, A - Dialkyldimethylquaternary ammonium salt of halogen ion, polyethyleneimine, polydimethylsiloxane-acetylene glycol polyether.

[0034] The present invention also provides a method for preparing the battery pack thermal insulation material, the method comprising:

[0035] S1: adding silane coupling agent modified aluminum silicate ceramic fiber, vermiculite, perlite, inorganic binder, vermiculite, perlite, halogenated polyethylene, dialkyl dimethyl quaternary ammonium salt, polyethyleneimine, and polysiloxane-polyether copolymer to deionized water respectively according to mass ratio, and mixing them uniformly to obtain a mixed slurry;

[0036] S2: The mixed slurry obtained in S1 is squeezed into a mesh, and then filtered and dehydrated by a mesh curtain; and dried to obtain a thermal insulation material base material;

[0037] S3: Immerse the thermal insulation material substrate in silica sol. The configuration of silica sol is: by mass, the ratio of aerogel precursor: alcohol organic solvent: sodium bicarbonate is (40 parts-120 parts): (100 parts-220 parts): (1 part-5 parts), gel, modify, and supercritically dry to obtain a thermal insulation material. Silica aerogel is formed on the surface of the thermal insulation material substrate, which can isolate the influence of moisture in the battery pack on the perlite, thereby reducing the corrosion of the thermal insulation material to the metal in the battery pack. In addition, through the method of suction filtration and dehydration, the inorganic adhesive can be more evenly and quickly dispersed in the thermal insulation material, and the various substances in the thermal insulation material can be quickly bonded together. The performance modification in S3 can improve the hydrophobicity of the thermal insulation material.

[0038] As a further embodiment, the specific operation of the web extrusion in S2 is to distribute the mixed slurry in S1 on the web curtain by water flow, and then extrude the slurry into a web by a φ=105 pressure roller. Those skilled in the art can select different sizes of pressure rollers for operation based on actual conditions.

[0039] As a further solution, in order to promote uniform dispersion of the various substances in the mixed slurry in S1, the addition and mixing can be carried out in steps. As an example: first, silane coupling agent-modified aluminum silicate ceramic fiber is added to deionized water, mixed evenly, and then the inorganic binder, vermiculite, perlite, halogenated polyethylene, dialkyl dimethyl quaternary ammonium salt, polyethyleneimine, and polysiloxane-polyether copolymer are added separately. To further improve the uniformity of the various substances in the slurry, the vermiculite and perlite can be crushed.

[0040] As a further solution, stirring can be selected as a method of uniform mixing, wherein the stirring speed is 400 r / min-600 r / min and the stirring time is 10 min-30 min. Those skilled in the art can adjust the stirring speed and time according to actual conditions to achieve the purpose of fully mixing the slurry.

[0041] As a further solution, the slurry viscosity of the mixed slurry in S1 is in the range of 300 mPa·s to 600 mPa·s.

[0042] As a further solution, the drying temperature in S2 is set to 80-100° C. and the drying time is 1.5 h to 3.5 h.

[0043] As a further embodiment, the immersion time in S3 is 8-12 seconds. Those skilled in the art will need to ensure that the thermal insulation material substrate is completely immersed in the silica sol. In the present invention, in S3, the mass fraction of the aerogel precursor supported on the thermal insulation material substrate is 2-6 parts by mass by immersion.

[0044] As a further solution, the gelling condition in S3 is that the temperature of the gelling is between 30°C and 35°C.

[0045] As a further solution, the modification conditions in S3 are as follows: adding a modifier with a concentration of 2%-8% at a temperature of 50°C-80°C, the added mass of the modifier being 5%-15% of the mass of the silica sol loaded on the insulation material substrate, and the modification is carried out for 15h-40h.

[0046] As a further solution, the supercritical drying condition in S3 is carbon dioxide supercritical drying for 5h-20h, wherein the carbon dioxide pressure is 13MPa-18MPa.

[0047] The characteristics and beneficial effects of the present invention are:

[0048] (1) The battery pack insulation material obtained by the method of the present invention has the characteristics of low thermal conductivity and high temperature resistance, a wide range of product applications, a simple production process, and excellent thermal insulation performance.

[0049] (2) The battery pack insulation material of the present invention is particularly suitable for use in battery packs. It can not only stabilize the extrusion force on the battery cells in the battery pack to avoid loosening, but also has expansion properties.

[0050] (3) In the method of the present invention, by adjusting the combination of vermiculite and perlite, the expansion volume of the battery pack insulation material can be regulated. When the battery pack is under a long cycle operating voltage, the insulation material has a smaller volume expansion rate, thereby improving the insulation performance and thus improving the stability of the battery pack. When the battery pack is in thermal runaway, the insulation material has a larger volume expansion rate, thereby preventing the occurrence of fire caused by thermal runaway, thereby improving the safety of the battery pack.

[0051] (4) The thermal conductivity of the battery pack insulation material obtained by the present invention is 0.015W·m -1 ·K -1 -0.03W·m -1 ·K -1 between. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the battery pack insulation material in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention.

[0053] Figure 1 The prepared battery pack thermal insulation material.

[0054] Figure 2 It is a thermal insulation material for battery packs that have been burned by high temperatures. DETAILED DESCRIPTION

[0055] To facilitate understanding of the battery pack insulation material of the present invention, the battery pack insulation material of the present invention will be described in more detail below, with examples of the present invention provided, but the scope of the present invention is not limited thereby.

[0056] Examples 1 to 14 and Comparative Examples 1 to 5 of the present invention were all prepared according to the method of the present invention. In each example and comparative example, the variable parameters are as shown in Tables 1 and 2, and the other parameters are the same.

[0057] S1: First, add the silane coupling agent modified aluminum silicate ceramic fiber to deionized water according to the mass ratio, mix evenly, and then add the inorganic binder, vermiculite, perlite, halogenated polyethylene, dialkyl dimethyl quaternary ammonium salt, polyethylene imine, and polysiloxane-polyether copolymer respectively, and mix evenly to obtain a mixed slurry; the mass ratio of the silane coupling agent modified aluminum silicate ceramic fiber and the halogenated polyethylene in the composite corrosion inhibitor is 2:1; the mass ratio of the dialkyl dimethyl quaternary ammonium salt, polyethylene imine, and polysiloxane-polyether copolymer in the composite flexibility agent is 1:1:2.5. Among them, the inorganic binder includes aluminum oxide powder, aluminum silicate powder, and sodium silicate, and the mass ratio of aluminum oxide powder, aluminum silicate powder, and sodium silicate is 30:30:60.

[0058] S2: The mixed slurry obtained in S1 is squeezed into a mesh, a vacuum negative pressure is added under the mesh to increase the filtration rate, and then the mesh is impregnated; dried to obtain a thermal insulation material base material;

[0059] S3: Immerse the thermal insulation material substrate in a silica sol with a mass ratio of aerogel precursor, alcoholic organic solvent, and sodium bicarbonate of 80:160:3. The sol is then gelled, modified, and supercritically dried to obtain the thermal insulation material. The silica aerogel formed on the surface of the thermal insulation material substrate isolates the perlite from moisture in the battery pack, thereby reducing corrosion of the thermal insulation material on the metal in the battery pack.

[0060] The specific operation of extrusion into a mesh in S2 is to distribute the mixed slurry in S1 on the mesh curtain through water flow, and then extrude the slurry into a mesh through a φ=105 pressure roller.

[0061] The uniform mixing method in S1 can be stirring, the stirring speed is 500 r / min, the stirring time is 20 min, and the viscosity of the mixed slurry is 400 mPa·s.

[0062] The drying conditions in S2 were drying in a microwave with a length of 30 m for 2 h.

[0063] The immersion time in S3 is 10 seconds. The gelation temperature in S3 is 35°C. The modification condition in S3 is to completely immerse the thermal insulation material substrate in a 5% hexamethyldisilazane solution at 60°C for 30 hours. The added mass of hexamethyldisilazane solution is 10% of the mass of the silica sol loaded on the thermal insulation material substrate. The supercritical drying condition in S3 is to supercritically dry the thermal insulation material with carbon dioxide for 10 hours at a carbon dioxide pressure of 15 MPa.

[0064] The present invention discloses a method for preparing a polysiloxane-polyether copolymer. The method comprises reacting an acetylene glycol polyether with dimethylsiloxane in a sealed environment under the action of a chloroplatinic acid catalyst. The reaction temperature is 100° C. and the reaction time is 2 hours. The molar ratio of the acetylene glycol polyether to the dimethylsiloxane is 1:1, and the yield of the polysiloxane-polyether copolymer obtained is 95%. The polysiloxane-polyether copolymer obtained has an average weight-average molecular weight of 20,000-30,000.

[0065] The present invention provides a method for preparing silane coupling agent-modified aluminum silicate ceramic fibers. The method comprises: mixing a silane coupling agent and water in a weight ratio of 1:95 to prepare a treatment solution; placing aluminum silicate ceramic fibers in the treatment solution for a primary soaking, grinding, and stirring; filtering and drying the fibers; then placing the fibers in the treatment solution for a secondary soaking, filtering, and drying the fibers to obtain pretreated aluminum silicate ceramic fibers; and subjecting the pretreated aluminum silicate ceramic fibers to a densification physical modification treatment, pre-oxidation, low-temperature carbonization, and high-temperature carbonization, respectively, to obtain the modified aluminum silicate ceramic fibers. The densification physical modification treatment is performed in air at 160°C with a 5% secondary elongation for 10 minutes. The pre-oxidation treatment is performed in air at 300°C with a 10% elongation for 150 minutes. The low-temperature carbonization treatment satisfies at least the following conditions: stretching at 10% elongation and carbonization at 600°C for 10 minutes under a nitrogen atmosphere. High-temperature carbonization: Carbonization was performed at 1300°C for 3 minutes under a nitrogen atmosphere and a 5% elongation. The primary immersion temperature was 40°C for 40 minutes, and the secondary immersion temperature was 50°C for 60 minutes. The drying temperature was 60°C.

[0066] The present invention also uses the obtained battery pack insulation material in the battery pack, and tests the cycle performance of the battery pack:

[0067] Cycling performance test: At 25°C, the battery pack was subjected to a 1C / 1C cycle test with a charge and discharge voltage range of 2.8-4.2V. The test was stopped when the capacity decayed to 80% of the initial discharge capacity.

[0068] Thermal conductivity test: The test is carried out in accordance with the national standard GB10295-88 Determination of steady-state thermal resistance and related properties of thermal insulation materials (heat flow meter method). The test equipment is Xiangtan Xiangke brand DRS-3A thermal conductivity tester, which tests the thermal conductivity of each insulation material at 1000℃.

[0069] Bending stiffness test: A bending stiffness tester (KATO, Japan, KES-FB2S) was used to perform bending stiffness tests on the thermal insulation materials provided in Examples 1-14 and Comparative Examples 1-5 to characterize their flexibility. The test results are shown in Table 3.

[0070] Results and Analysis

[0071] Table 1 Raw material formula of the embodiments of the present invention and comparative examples

[0072]

[0073]

[0074] Table 2 Formulas of composite preservatives and composite flexibilizers in the examples of the present invention and comparative examples

[0075]

[0076] Table 3 Test results of the embodiments of the present invention and comparative examples

[0077]

[0078] The battery pack insulation material was successfully prepared by the method of the present invention, as shown in Table 1-Table 3. Figure 1-Figure 2 As shown. We can find that the battery pack insulation materials of Examples 1 to 14 of the present invention have good thermal insulation performance and flexibility on the basis of a thin thickness, and the thermal insulation material obtained by the present invention is used in the battery to isolate the heat conduction between the battery cells in different working environments of the battery pack, thereby helping to improve the safety of the battery pack, and the thermal insulation material of the present invention can also have a certain squeezing force on the battery cells in the battery pack, thereby helping to reduce the loosening between the battery cells in the battery pack, thereby improving the working stability of the battery pack. We can verify through Table 3 that Examples 1 to 14 are significantly better than Comparative Example 1. It can be seen that using the thermal insulation material obtained by the present invention in the battery pack can significantly improve the cycle performance of the battery pack.

[0079] We believe that the present invention obtains thermal insulation materials for use in battery packs and improves the electrical performance and safety performance of battery packs, mainly because of the design of the thermal insulation materials of the present invention. In the present invention, we designed the raw materials for forming the thermal insulation materials, and the raw materials of the thermal insulation materials include vermiculite, perlite, aerogel precursor, composite anti-corrosion agent, and composite flexibilizer. In the design of the present invention, the added aerogel precursor forms silica aerogel. On the one hand, the silica aerogel has specific resilience and exerts a certain extrusion force on the battery cells in the battery pack, which is beneficial to improve the stability between the battery cells; on the other hand, in the low temperature stage, the silica aerogel can maintain the stability of the cycle performance of the battery pack, thereby ensuring the normal working state of the battery pack. In order to improve the safety of the battery pack under long cycles, we have further added vermiculite and perlite. First, the combination of perlite and vermiculite can exert thermal insulation properties in the high temperature stage, which is beneficial to improving the safety performance of the battery pack and preventing thermal runaway of the battery pack; second, the amount of vermiculite and perlite added can be adjusted to regulate the expansion volume of the thermal insulation material, and the loosening between the battery cells can be reduced under long cycles of the battery pack, and it can also be used in battery packs of different sizes. In order to improve the corrosion resistance and flexibility of the thermal insulation material, thereby ensuring that the thermal insulation material can stably exert its thermal insulation performance, and reduce the volume proportion of the thermal insulation material in the battery pack, which is beneficial to the improvement of the energy density of the battery pack, we have further designed a composite anti-corrosion agent and a composite flexibility agent. We can verify by comparing Examples 1 to Example 14 with Comparative Example 1 that the addition of composite anti-corrosion agents and composite flexibility agents can ensure the performance of the thermal insulation material, which is beneficial to the stability of the cycle performance of the battery pack.

[0080] Based on this, I further designed a composite corrosion inhibitor consisting of silane coupling agent-modified aluminum silicate ceramic fiber and halogenated polyethylene, and a composite flexibilizer consisting of dialkyl dimethyl quaternary ammonium salt, polyethyleneimine, and polysiloxane-polyether copolymer. The dialkyl dimethyl quaternary ammonium salt, in combination with polyethyleneimine, can reduce the flow of static charge during battery pack cycling, thereby improving battery pack safety. Halogenated polyethylene, combined with silane coupling agent-modified aluminum silicate ceramic fiber, not only enhances the insulation's corrosion resistance but also improves its flame retardancy and chemical resistance. Furthermore, combining silane coupling agent-modified aluminum silicate ceramic fiber with vermiculite and perlite not only improves the thermal insulation performance of the battery pack, but also allows for further control of the amount of vermiculite and perlite added to balance the material's lightness and thermal performance. Silane coupling agent-modified aluminum silicate ceramic fibers not only improve the corrosion resistance of aluminum silicate ceramic fibers, but also promote the uniformity of dispersion of aluminum silicate ceramic fibers and polysiloxane-polyether copolymers, thereby imparting improved flexibility and corrosion resistance to the entire thermal insulation material. Thus, the design of the thermal insulation raw materials in the present invention provides a thermal insulation material particularly suitable for battery packs, and the use of the thermal insulation material of the present invention in battery packs can improve the cycle performance and safety performance of the battery pack.

[0081] On this basis, we further studied how to further improve the performance of the thermal insulation material, such as comparing Examples 1 to 14 with Comparative Examples 2 to 5, in order to obtain a thermal insulation material with better performance.

[0082] First, we studied the amount of vermiculite added. As shown in Examples 1-3, we can find that when the amount of vermiculite added is greater, although the thermal insulation performance of the thermal insulation material will increase, the volume expansion rate of the thermal insulation material will increase significantly, and the flexibility will decrease significantly. On the one hand, it will affect the serious expansion of the battery pack. On the other hand, the flexibility of the thermal insulation material will decrease. The thermal insulation material will occupy more volume in the battery pack during the bending or folding process of the battery pack, thereby affecting the reduction in the volume ratio of the battery cells in the battery pack, and the energy density of the battery pack will decrease. When the amount of vermiculite added is less, it will directly affect the thermal insulation performance, and ultimately affect the decline in the cycle performance of the battery pack. We can also verify this through Comparative Examples 2-3. Similarly, perlite is used in conjunction with vermiculite to improve the thermal insulation performance of the thermal insulation material. We can compare Example 1 and Example 4-5. The amount of perlite added and the amount of vermiculite added have similar effects, which is verified by Comparative Examples 4-5. Therefore, we further prefer that the addition amount of vermiculite and perlite is (4 parts-6 parts): (4 parts-6 parts).

[0083] On this basis, we further studied the addition amount of aerogel precursor, such as the comparison of Example 1, Example 6-Example 7. We can find that the aerogel precursor is used to generate silica aerogel, which can maintain the stability of the battery pack at low temperatures. However, if the amount of aerogel precursor added is too little, it will not form enough silica aerogel, which will affect the operation of the battery at low temperatures. When the amount added is too much, it may affect the proportion of other raw materials added to the slurry, thereby affecting the performance of the thermal insulation material. From the comparison of Example 1, Example 6-Example 7, it was found that the aerogel precursor has little effect on the performance of the thermal insulation material and the cycle performance of the battery pack within the addition range of the present invention.

[0084] We also studied the addition quality of the composite anticorrosive agent and the composite flexibilizer, as shown in Example 1, Example 8-Example 9, and Example 1, Example 10-Example 11. The composite anticorrosive agent improves the corrosion resistance of the thermal insulation material. When the addition amount is too low, the thermal insulation material may be corroded, thereby affecting the thermal insulation performance of the thermal insulation material. When the composite anticorrosive agent is added in a larger amount, the amount of silane coupling agent-modified aluminum silicate ceramic fiber in the composite anticorrosive agent is increased, which will reduce the flexibility of the thermal insulation material. The addition amount of the composite flexibilizer directly affects the flexibility of the thermal insulation material. When the addition amount is higher, the flexibility increases, but due to the lack of mechanical strength, it cannot provide a certain squeezing force between the battery cells, and the stability of the battery cells will decrease. When the addition amount of the composite flexibilizer is even smaller, the flexibility of the thermal insulation material will decrease. Therefore, we further prefer that the addition amount of the composite anticorrosive agent and the composite flexibilizer is (0.7 parts-0.9 parts): (1.6 parts-1.8 parts).

[0085] Finally, we also studied the interaction between different composite anticorrosive agents and composite flexibilizers in order to find a better combination. For example, a comparison of Example 1, Example 12-Example 14 showed that the thermal insulation material of Example 1 has a more balanced performance. In addition, the thermal insulation material of Example 1 has a smaller volume expansion rate during the long cycle of the battery and also has better cycle performance. Therefore, we further prefer that the composite anticorrosive agent includes silane coupling agent modified aluminum silicate ceramic fiber and polyvinyl fluoride; the composite flexibilizer includes R1 and R2 as perfluorosubstituted methyl, A - Dialkyldimethylquaternary ammonium salt of halogen ion, polyethyleneimine, polydimethylsiloxane-acetylene glycol polyether.

[0086] In summary, the thermal insulation material of the present invention has good thermal insulation performance, and the thermal insulation material of the present invention is used in a battery pack to improve the safety performance and cycle performance of the battery pack.

[0087] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A battery pack insulation material, characterized in that: The raw materials of the battery pack insulation material include vermiculite, perlite, aerogel precursor, composite anticorrosive agent, and composite flexibilizer. The ratio of the vermiculite, perlite, aerogel precursor, composite anticorrosive agent, and composite flexibilizer by mass is (3 parts-7 parts): (2 parts-8 parts): (2 parts-6 parts): (0.5 parts-1 part): (1.5 parts-2 parts); the composite anticorrosive agent includes silane coupling agent modified aluminum silicate ceramic fiber and halogenated polyethylene; the composite flexibilizer includes dialkyl dimethyl quaternary ammonium salt, polyethylene imine, and polysiloxane-polyether copolymer; The ratio of the silane coupling agent modified aluminum silicate ceramic fiber to the halogenated polyethylene is (1.5 parts to 2 parts): (0.5 parts to 1 part) by mass; The ratio of the dialkyldimethyl quaternary ammonium salt, polyethyleneimine, and polysiloxane-polyether copolymer is (0.5 part-1 part): (0.5 part-1 part): (2 parts-3 parts) by mass.

2. A battery pack insulation material according to claim 1, characterized in that: The halogenated polyethylene includes one or more of polyvinyl fluoride and polyvinyl chloride.

3. The battery pack insulation material according to claim 1, characterized in that: The dialkyl dimethyl quaternary ammonium salt has the structural formula (1): Structural formula (1) Wherein, R1 and R2 are each methyl, A - One selected from bicarbonate and halogen ions.

4. A battery pack insulation material according to claim 3, characterized in that: In the structural formula (1) of the dialkyldimethyl quaternary ammonium salt, R1 and R2 are each one of methyl groups having a fluorine-substituted group.

5. The battery pack insulation material according to claim 1, characterized in that: The polysiloxane in the polysiloxane-polyether copolymer includes polydimethylsiloxane.

6. The battery pack insulation material according to claim 5, characterized in that: The polyether copolymer in the polysiloxane-polyether copolymer includes acetylene glycol polyether.

7. The battery pack insulation material according to claim 1, characterized in that: The aerogel precursor includes a silicate.

8. The battery pack insulation material according to claim 7, characterized in that: The silicate includes one or more of methyl orthosilicate and ethyl orthosilicate.

9. The battery pack insulation material according to claim 1, characterized in that: The raw materials of the battery pack insulation material also include an inorganic binder, and the mass proportion of the inorganic binder in the raw materials is 7%-10%.

10. The battery pack insulation material according to claim 9, characterized in that: The inorganic binder includes aluminum oxide powder, aluminum silicate powder, and sodium silicate. The ratio of the aluminum oxide powder, aluminum silicate powder, and sodium silicate is (10 parts-50 parts): (10 parts-50 parts): (30 parts-90 parts) by mass.

11. The battery pack insulation material according to claim 3, characterized in that: The raw materials of the battery pack insulation material include vermiculite, perlite, aerogel precursor, composite anticorrosive agent, and composite flexibilizer. The ratio of the vermiculite, perlite, aerogel precursor, composite anticorrosive agent, and composite flexibilizer by mass is (4 parts-6 parts): (4 parts-6 parts): (2 parts-6 parts): (0.7 parts-0.9 parts): (1.6 parts-1.8 parts); the composite anticorrosive agent includes silane coupling agent modified aluminum silicate ceramic fiber and polyvinyl fluoride; the composite flexibilizer includes R1 and R2 being perfluorosubstituted methyl, A - Dialkyldimethylquaternary ammonium salt of halogen ion, polyethyleneimine, polydimethylsiloxane-acetylene glycol polyether.

12. The method for preparing the battery pack thermal insulation material according to any one of claims 1 to 11, characterized in that: The preparation method comprises: S1: adding silane coupling agent modified aluminum silicate ceramic fiber, vermiculite, perlite, inorganic binder, halogenated polyethylene, dialkyl dimethyl quaternary ammonium salt, polyethyleneimine, and polysiloxane-polyether copolymer to deionized water respectively according to mass ratio, and mixing them uniformly to obtain a mixed slurry; S2: The mixed slurry obtained in S1 is squeezed into a mesh, and then filtered and dehydrated by a mesh curtain; and dried to obtain a thermal insulation material base material; S3: Immerse the thermal insulation material substrate in silica sol. The configuration of silica sol is: by mass, the ratio of aerogel precursor: alcohol organic solvent: sodium bicarbonate is (40 parts-120 parts): (100 parts-220 parts): (1 part-5 parts), gel, modify, and supercritically dry to obtain the thermal insulation material.

13. The preparation method according to claim 12, characterized in that The drying temperature in S2 is 80° C.-100° C.; the drying time is 1.5 h-3.5 h.

14. The preparation method according to claim 12, characterized in that The temperature of the gel in S3 is 30°C-35°C.

15. The preparation method according to claim 12, characterized in that The modification temperature in S3 is 50-80° C., a modifier is added, the added mass of the modifier is 5%-15% of the mass of the silica sol loaded on the thermal insulation material substrate, and the modification time is 15h-40h.

16. The preparation method according to claim 12, characterized in that The supercritical drying condition in S3 is carbon dioxide supercritical drying for 5 h to 20 h, wherein the carbon dioxide pressure is 13 MPa to 18 MPa.

Images