Ceramic polyphosphazene composite material for thermal insulation of power battery and preparation method of ceramic polyphosphazene composite material

Abstract

The invention discloses a ceramic polyphosphazene composite material for power battery heat insulation and a preparation method thereof, and belongs to the field of battery heat insulation. Comprising the following raw materials: polyphosphazene rubber, fibers, a heat insulation agent and a compound fluxing agent, the heat insulation agent is selected from wollastonite powder, mica powder and other ceramizable fillers, and the heat insulation performance of the polyphosphazene composite material is further improved; the preparation method has the further contribution that high-performance fibers and a compound fluxing agent are introduced, so that the ablation resistance of the polyphosphazene composite material is improved, and the flame retardance is further improved. Tests show that the obtained ceramic polyphosphazene composite material is excellent in comprehensive performance, and excellent and reliable in mechanical property, heat insulation performance, thermal deformation resistance, heat insulation performance under actual high-temperature flames and burn-through resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of functional materials, and particularly relates to a ceramicized polyphosphazene for thermal insulation of power batteries and a preparation method thereof. BACKGROUND

[0002] With the increasing scale of electric vehicles and energy storage power stations, the application of thermal insulation materials in this field has also attracted more and more attention. Because of the unpredictability and harmfulness of lithium battery fire and explosion accidents, the thermal insulation materials that can effectively inhibit the spread of fire and reduce the risk of violent explosion are required to have more stringent multi-dimensional performance requirements. At present, ceramicized silicone rubber is widely used as a structural framework material for lithium battery thermal insulation, and is used together with thermal insulation aerogel as a core thermal protection layer. In this material combination, silicone rubber not only plays a role in thermal insulation, but also plays an important role in buffering the mechanical vibration of the battery pack.

[0003] Under this application background, compared with traditional ceramicized silicone rubber, the new generation of ceramicized polyphosphazene rubber shows more significant advantages: it has higher thermal stability and excellent flame retardant performance, and does not need to add other flame retardants, saving cost and being more environmentally friendly. The ceramicized polyphosphazene rubber maintains the same elastic modulus as silicone rubber, so that it has the inherent flexibility and shock absorption characteristics of rubber at room temperature, and through ceramicization, it achieves the high-temperature structural integrity and flame retardant performance that traditional ceramicized silicone rubber cannot achieve, so that it plays a significant function better than ceramicized silicone rubber under different service conditions. Therefore, in the era of increasing attention to lithium battery safety, the use of more safe and reliable ceramicized polymer composite materials to meet the market's heavy demand for safety has become the general expectation.

[0004] Polyphosphazene is an inorganic-organic hybrid polymer material with a main chain composed of phosphorus (P) and nitrogen (N) atoms through alternating single and double bonds. The large number of phosphorus and nitrogen elements in the main chain form a synergistic flame-retardant system, making the material exhibit excellent flame-retardant performance. During ablation, phosphorus atoms can generate phosphoric anhydride substances with strong dehydrating properties, promoting carbonization and forming a very dense carbon layer on the surface of the material, which can release non-combustible inert gas, dilute and isolate combustible gas and oxygen, and achieve the effect of cutting off the material matrix from oxygen, thus playing a gas-phase flame-retardant role. In addition, polyphosphazene rubber can produce highly reactive phosphorus-oxygen radicals (PO·) during combustion or pyrolysis, which can react with highly active radicals (such as H· and OH·) highly dependent on flame chain reactions to form stable intermediates, thereby interrupting the flame chain reaction. In summary, polyphosphazene rubber is a relatively ideal ablation-resistant and heat-insulating material. Currently, various types of polyphosphazene rubber have been widely used in places requiring high flame resistance. However, the carbon layer formed by the surface rubber matrix and organic fillers at high temperatures in the currently prepared polyphosphazene heat-insulating materials is not hard and dense enough, and the ablation-resistant and heat-insulating performance is limited, which cannot resist the scouring effect of high-temperature, high-pressure, and high-speed airflow. Therefore, in order to meet the requirements of ablation resistance and erosion resistance, inorganic fillers and fibers need to be added to increase the ablation resistance. The addition of inorganic fillers such as one or more of carbon black or white carbon black can bond the carbon layer formed at high temperatures after melting, making the carbon layer not prone to peeling and falling off, and to some extent, improving the ablation resistance of polyphosphazene rubber. The addition of polymer fibers and inorganic synthetic fibers can improve the ablation resistance of polyphosphazene rubber, but the addition of fibers may lead to a decrease in elongation at break. In the prior art, lower melting point functional fillers that can be ceramized are introduced into the system, such as low melting point glass powder and silicates. These substances in the material melt at high temperatures, connecting the carbon layer and other ablation materials into a solid network similar to the sintering process of ceramics, ultimately achieving the goal of densification, hence the term "ceramizable filler". However, the addition of such fillers can also lead to a decrease in the toughness of the heat-insulating material.

[0005] CN119978810A, CN120024091A, CN119708855A, CN203466178U, CN120082293A, CN119899455A, and CN119734494A each disclose some composite materials based on ceramizable functional fillers, and are used in the fields of fire-resistant cables, aerospace, etc., but none of them involves polyphosphazene as the main rubber in the ceramizable functional filler composite material, and there is no application research on the use of ceramized polyphosphazene rubber as a structural framework material for lithium battery insulation.

[0006] Based on the above research background, the application provides a kind of comprehensive performance excellent ceramicizable polyphosphazene type flame-retardant insulation composite material and its preparation method, polyphosphazene composite material with the addition of fiber, heat insulating agent and compound fluxing agent is prepared, the material is comprehensively tested and evaluated from the aspects of heat insulation performance, mechanical property etc. SUMMARY

[0007] The application mainly aims at the thermal protection technology of equipment and facilities in extreme environment, and provides a kind of high flame-retardant insulation composite material which can be used in extreme environment. The contribution of the application is firstly to select wollastonite powder and mica powder and other ceramicizable fillers, which further improves the heat insulation performance of polyphosphazene composite material; the further contribution of the application is to introduce high-performance fibers and compound fluxing agents, which improves the ablation resistance of polyphosphazene composite material and further improves the flame-retardant performance. After testing, the flame-retardant insulation polyphosphazene composite material obtained by the application has excellent comprehensive performance, and the mechanical property, heat insulation performance, heat deformation resistance and heat insulation and burn-through resistance in actual high-temperature flame are all excellent and reliable.

[0008] The object of the application is achieved by the following technical solutions:

[0009] A kind of high flame-retardant insulation ceramicized polyphosphazene composite material, including the following mass parts of raw materials: 100 parts of polyphosphazene rubber with different substituent groups, 1-20 parts of high-performance fiber, 3-40 parts of heat insulating agent, 3-30 parts of compound fluxing agent, 3-30 parts of one or two of white carbon black or carbon black; preferably, the ceramicized polyphosphazene composite material includes the following mass parts of raw materials: 100 parts of polyphosphazene rubber, 5-10 parts of various fibers, 20-30 parts of heat insulating agent, 10-20 parts of compound fluxing agent, 15-25 parts of one or two of white carbon black or carbon black.

[0010] Further raw materials also include vulcanizing agent and vulcanizing accelerator, the vulcanizing agent is selected from one or more of D, DM and sulfur, the vulcanizing accelerator is DCP, di-tert-butyl peroxide (DTBP) and the like, wherein the vulcanizing agent is 1-10 parts, and the vulcanizing accelerator is 1-5 parts;

[0011] Further raw materials also include 1-10 parts of stearic acid and 1-10 parts of zinc oxide.

[0012] The polyphosphazene rubber is characterized in that the side groups on the phosphorus site are one or more of aryloxy group, aryl group and methoxy group, ethoxy group, propoxy group, butoxy group, trifluoroethoxy group or octafluoropentyl group.

[0013] The high-performance fiber includes at least one of poly-p-phenylene-benzobisoxazole fiber (PBO), polyimide fiber (PI), aramid fiber (AF), carbon fiber and basalt fiber (BF); preferably, the fiber is PBO, carbon fiber and PI fiber.

[0014] Further, the heat insulating agent is a mixture of wollastonite powder and mica powder; the mass content of the wollastonite powder in the heat insulating agent is 50-99wt%; and the mass content of the mica powder is 1-50wt%.

[0015] The complex fluxing agent is one or both of boron oxide and calcium oxide; preferably both, and the complex ratio of boron oxide to calcium oxide is 1-5:1-5.

[0016] The application also provides a preparation method of the high-flame-retardant heat-insulating ceramized polyphosphazene composite material, comprising the following steps:

[0017] S1 Raw material proportioning: according to the proportioning, the corresponding mass parts of polyphosphazene rubber, high-performance fiber and corresponding other raw materials are weighed;

[0018] S2 Internal mixing: the polyphosphazene rubber, heat insulating agent and complex fluxing agent and other raw materials obtained in step S1 are added to an internal mixer, and pressure stirring is performed to fully mix the materials;

[0019] S3 Open mixing: the vulcanizing agent, vulcanization accelerator, high-performance fiber and the material obtained in step S2 are added to a two-roll open mill to obtain a ceramized polyphosphazene compound;

[0020] S4 Sheet forming: adjusting the distance between the two rolls, the ceramized polyphosphazene compound obtained in step S3 is sheet formed on the two-roll open mill with a desired thickness, and is left to stand for at least 24 hours;

[0021] S5 Vulcanization forming: the ceramized polyphosphazene compound obtained in step S4 is placed in a mold for pressure and temperature vulcanization, and the high-flame-retardant heat-insulating ceramized polyphosphazene composite material is obtained.

[0022] Preferably in step S2, the stirring temperature of the internal mixer is 30-40℃, the stirring speed is 50-300r / min, and the time length is 15-25min.

[0023] In step S5, the temperature of the mold pressing vulcanization forming is 130-165℃, the pressure is 10-20MPa, and the mold pressing time length is between 30-70min, and the specific value is determined by a rotorless vulcanization instrument.

[0024] The application firstly selects the ceramizable heat insulating fillers such as wollastonite powder and mica powder, further improves the heat insulation performance of the polyphosphazene composite material; and further contributes to the introduction of high-performance fiber and complex fluxing agent, which improves the ablation resistance of the polyphosphazene composite material and further improves the flame retardant performance. Through testing, the ceramized polyphosphazene composite material obtained by the application has excellent comprehensive performance, and the mechanical properties, heat insulation performance, heat deformation resistance and heat insulation and ablation resistance in actual high-temperature flame are all excellent and reliable. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a schematic diagram of the flame combustion high temperature test system of the present application.

[0026] Figure 2 is a high flame retardant insulation ceramic polyphosphazene composite material being tested for insulation.

[0027] Figure 3 is the ablation appearance of the front and back of the material after insulation testing of Example 2.

[0028] Figure 4 is the SEM image of the material after insulation testing of Example 4

[0029] Figure 5 is the heat distortion temperature test diagram of Examples 1, 2, 3, 4, and 5 DETAILED DESCRIPTION

[0030] The ceramic polyphosphazene composite material obtained by the present application is subjected to the following performance tests:

[0031] 1. Mechanical property test: A GNT10 electronic universal mechanical tensile testing machine from Suzhou Jianzhuo Co., Ltd. is used to test the tensile strength and elongation at break of the polyphosphazene insulation material prepared in the examples according to the specific requirements of standard GB / T 528-2009. The sample size is 100x100x2mm, the sample is cut into corresponding dumbbell-shaped samples of type 2 using a type 2 cutter, each group of samples is not less than 5, the tensile rate is set to 500mm / min, the test environment humidity is 20%RH, and the temperature is 20℃.

[0032] 2. Thermal conductivity test: A TC3000E hot-wire method thermal conductivity instrument from Xi'an Xiayi Electronics Technology Co., Ltd. is used to test the thermal conductivity of the final prepared flame-retardant insulation composite material according to GB / T 11205-2009. The sample size is 25mmx25mmx3mm, the test humidity is 20%RH, and the temperature is 25℃.

[0033] 3. Insulation performance test: A self-made flame combustion high temperature test system (see Figure 1 ) is used to test the back surface temperature of the polyphosphazene insulation material prepared by the present application at 1000℃ for 10min: a butane spray gun is used as the ignition source, the flame is perpendicular to the front surface of the sample, the back surface temperature is monitored in real time by a surface thermocouple directly contacting the back surface of the sample; the temperature collection time interval is 1s, the total time is set to 10min, and the data is recorded by the test software. The sample size is 100mmx100mmx2mm.

[0034] The existing technology is basically to test the thermal conductivity coefficient and linear ablation rate, and few to test the actual heat insulation performance under specific high-temperature flame. The thermal conductivity coefficient can reflect the heat insulation performance of the material in theory, but the effect is different in specific implementation. According to the influence of the use environment, specific problems, air flow and other conditions, the real heat insulation data of the material may be different from the thermal conductivity. The present application tests the thermal conductivity and also tests the heat insulation under the real situation. Specifically, the stable temperature of the back surface of the sample is tested when the butane flame is vertically burned on the front surface of the sample at about 1000 DEG C.

[0035] The present application will be further described in detail below in combination with the drawings and specific examples.

[0036] Example 1

[0037] 100 parts of aralkyloxy polyphosphazene rubber, 15 parts of wollastonite powder, 15 parts of mica powder, 20 parts of at least one of carbon black or white carbon black, 3 parts of zinc oxide, 3 parts of stearic acid, 15 parts of a complex fluxing agent with a complex ratio of 1:3 are mixed on a mixer for 20 min, then 5 parts of PBO fiber, 4 parts of vulcanization accelerator D, DM, 1 part of vulcanizing agent DCP and 2 parts of sulfur are mixed on a two-roll open mill, and the sheet is extruded for 20 times until the filler is uniformly dispersed; wherein the stirring temperature of the mixer is 30-40 DEG C, the stirring speed is 50-300 rpm, the mixing temperature of the two-roll mixer is 25 DEG C, and the roll speed ratio of the two-roll mixer is 3:1. Adjust the distance between the two rolls, and prepare the uniformly mixed sample into a semi-finished product with a size of 100mm*100mm*2mm and 100mm*100mm*4mm, place it in the same mold for 24h, and then vulcanize it in a flat vulcanizing machine, the vulcanization temperature is controlled at 160 DEG C, the pressure is set at 18MPa, and the vulcanization time is between 62min, which is determined by a rotorless vulcanizing instrument, to obtain a high flame-retardant heat-insulating ceramicized polyphosphazene composite material. The obtained heat-insulating material is tested according to the above test method, and the results are shown in Table 1.

[0038] Example 2

[0039] The difference between this embodiment and example 1 is that the PBO fiber is replaced by PI fiber with the same parts, and the rest is the same as example 1

[0040] Example 3

[0041] The difference between this embodiment and example 1 is that the PBO fiber is replaced by AF fiber with the same parts, and the rest is the same as example 1

[0042] Example 4

[0043] The difference between this embodiment and example 1 is that the PBO fiber is replaced by CF fiber with the same parts, and the rest is the same as example 1

[0044] Example 5

[0045] The difference between this example and Example 1 is that the PBO fibers are replaced by the same amount of GF fibers, and the rest is the same as Example 1

[0046] Example 6

[0047] The difference between this example and Example 1 is that the PBO fibers are replaced by the same amount of BF fibers, and the rest is the same as Example 1

[0048] Comparative Example 1

[0049] The difference between this comparative example and Example 1 is that no fibers are added, and the rest is the same as Example 1

[0050] Comparative Example 2

[0051] The difference between this comparative example and Example 1 is that no fibers are added, and the compounded fluxing agent is replaced by the same amount of low-temperature glass powder 1 with a melting point of 300°C, and the addition of fibers is removed, and the rest is the same as Example 1

[0052] Comparative Example 3

[0053] The difference between this example and Example 1 is that the compounded fluxing agent is replaced by the same amount of low-temperature glass powder 2 with a melting point of 450°C, and the addition of fibers is removed, and the rest is the same as Example 1

[0054] Comparative Example 4

[0055] The difference between this example and Example 1 is that the compounded fluxing agent is replaced by the same amount of low-temperature glass powder 3 with a melting point of 600°C, and the addition of fibers is removed, and the rest is the same as Example 1

[0056] Comparative Example 5

[0057] The difference between this example and Example 1 is that the compounded fluxing agent is replaced by the same amount of boron oxide, and the addition of fibers is removed, and the rest is the same as Example 1.

[0058] Comparative Example 6

[0059] The difference between this comparative example and Example 1 is that no thermal insulating agent, fluxing agent, and fibers are added, and the rest is the same as Example 1.

[0060] Table 1

[0061] It can be found from the data in Table 1 that the high flame-retardant and heat-insulating ceramicized polyphosphazene composite material prepared in the application has excellent comprehensive performance, and exhibits good mechanical properties and heat-insulating properties. The application selects a compound of wollastonite powder and mica powder as the heat-insulating agent, and a compound of boron oxide and calcium oxide as the fluxing agent, which can comprehensively match the characteristics of the fillers, and play a synergistic effect, so that the mechanical properties, heat-insulating properties and burn resistance of the obtained heat-insulating material are simultaneously optimized. If CF fiber is introduced into the formula, it can be found from the comparison between Example 4 and Comparative Example 1 that the heat distortion temperature of the heat-insulating material of Example 4 is increased, the maximum back temperature is reduced, and the heat-insulating material is not burned through in the 10 min ablation process. The introduction of high-performance fiber further improves the comprehensive performance of the polyphosphazene heat-insulating composite material.

[0062] The above-described specific embodiments are preferred embodiments of the present application, and the present application should not be limited to the disclosed content. Any equivalent or modification made without departing from the disclosed spirit of the present application falls within the scope of the present application.

Claims

1. A high flame retardant thermally insulating ceramified polyphosphazene composite material, characterized in that, The raw materials include the following quality parts: 100 parts of polyphosphazene rubber with different substituents, 1-20 parts of high-performance fibers, 3-40 parts of heat insulating agents, 3-30 parts of compound fluxing agents, and one or both of 3-30 parts of white carbon black or carbon black; preferably 100 parts of polyphosphazene rubber, 5-10 parts of various fibers, 20-30 parts of heat insulating agents, 10-20 parts of compound fluxing agents, and one or both of 15-25 parts of white carbon black or carbon black.

2. A high flame resistant, thermally insulating ceramifiable polyphosphazene composite material according to claim 1, characterized in that, The raw materials also include vulcanizing agents and vulcanizing accelerators, the vulcanizing agents are selected from one or more of D, DM, and sulfur, and the vulcanizing accelerator is DCP, wherein the vulcanizing agent is 1-10 parts, and the vulcanizing accelerator is 1-5 parts.

3. A high flame resistant, thermally insulating ceramifiable polyphosphazene composite material according to claim 1, characterized in that, The raw materials also include 1-10 parts of stearic acid and 1-10 parts of zinc oxide.

4. A high flame resistant, thermally insulating ceramifiable polyphosphazene composite material according to claim 1, characterized in that, The polyphosphazene rubber is characterized in that the side groups on the phosphorus sites are one or more of aryloxy groups, aryl groups, and methoxy groups, ethoxy groups, propoxy groups, butoxy groups, trifluoroethoxy groups, or octafluoropentyl groups with fatty chain segments.

5. A high flame resistant, thermally insulating ceramifiable polyphosphazene composite material according to claim 1, characterized in that, The high-performance fibers include at least one of poly-p-phenylene-benzobisoxazole fibers (PBO), polyimide fibers (PI), aramid fibers (AF), carbon fibers, and basalt fibers (BF); preferably, the fibers are PBO, carbon fibers, and PI fibers.

6. A high flame resistant, thermally insulating ceramifiable polyphosphazene composite material according to claim 1, characterized in that, The heat insulating agent is a mixture of wollastonite powder and mica powder; the mass content of wollastonite powder in the heat insulating agent is 50-99 wt%; and the mass content of mica powder is 1-50 wt%.

7. A high flame retardant, thermally insulating ceramifiable polyphosphazene composite material according to claim 1, characterized in that, The compound fluxing agent is a compound of one or both of boron oxide and calcium oxide; preferably, the compound is a compound of both boron oxide and calcium oxide, and the compound ratio of boron oxide to calcium oxide is 1-5:1-5.

8. A process for the preparation of a high flame retardant thermally insulating ceramifiable polyphosphazene composite material according to any one of claims 1 to 7, characterized in that, The method includes the following steps: S1 Raw material proportioning: according to the proportioning, the corresponding quality parts of polyphosphazene rubber, high-performance fibers, and other corresponding raw materials are weighed; S2 Internal mixing: the raw materials obtained in step S1 are added to an internal mixer, and pressure stirring is performed to fully mix the materials; S3 Open mixing: the vulcanizing agent and the vulcanizing accelerator are added to the material obtained in step S2 in a two-roll open mill to obtain a ceramic polyphosphazene compound; S4 Sheet forming: the distance between the two rolls is adjusted, the ceramic polyphosphazene compound obtained in step S3 is formed into a sheet with a desired thickness on the two-roll open mill, and the sheet is left to stand for at least 24 hours; S5 Vulcanization forming: the sheet with a certain thickness obtained in step S4 is placed in a mold for pressure and temperature vulcanization, and a ceramic polyphosphazene composite material is obtained.

9. The method of claim 8, wherein, In step S2, the stirring temperature of the internal mixer is 30-40°C, the stirring speed is 50-300 rpm, and the stirring time is 15-25 min; In step S5, the temperature for mold vulcanization forming is 130-165°C, the pressure is 10-20 MPa, and the mold time is 30-70 min, and the specific value is determined by a rotorless vulcanization instrument.

10. The application of a high-flame-retardant heat-insulating ceramic polyphosphazene composite material according to any one of claims 1-7, as a heat insulation layer of a power battery.

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