Flame-retardant composite phase change material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of phase change materials, and particularly relates to a flame-retardant composite phase change material as well as a preparation method and application thereof. The invention provides a flame-retardant composite phase-change material. The flame-retardant composite phase-change material comprises a phase-change material, a high-molecular polymer, a heat-conducting agent and a flame retardant, the flame retardant comprises hydrated inorganic salt. The flame-retardant composite phase change material provided by the invention can perform reversible cycle heat absorption at 40-55 DEG C (that is, thermal management temperature control is performed on a battery under a conventional working condition), and can absorb a large amount of heat generated by the battery before thermal runaway of the battery, that is, the flame-retardant composite phase change material can absorb a large amount of heat at a temperature interval of 70-200 DEG C, so that the thermal runaway of the battery is avoided. The time of the battery in the second stage of thermal runaway is prolonged; moreover, after the battery is subjected to thermal runaway, the product has high flame retardance, so that flame spreading can be prevented, and the safety risk after the battery is subjected to thermal runaway is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of phase change materials, and particularly relates to a flame-retardant composite phase change material, a preparation method thereof and an application thereof. Background Art

[0002] With the rapid development of the economy and the continuous progress of science and technology, concepts such as low-carbon economy and sustainable development have increasingly attracted people's attention. Among them, using green and environmentally friendly new energy electric vehicles to replace traditional fuel vehicles is one of the important strategies to address energy depletion and environmental pollution. Although new energy electric vehicles are developing rapidly, there is still a large market space. One of the key factors affecting the further development of new energy electric vehicles is consumers' concern about the insecurity of new energy electric vehicles. Lithium-ion batteries are the main energy carriers of current new energy electric vehicles due to their advantages such as high energy density, long cycle life, and fast charge and discharge capabilities. The insecurity of new energy electric vehicles mainly stems from the thermal safety problem of lithium-ion battery modules. During the conventional charge and discharge process, due to the continuous progress of the electrochemical reaction, lithium-ion batteries will generate a large amount of heat. When the accumulated heat cannot be effectively released, it will act on the lithium-ion battery itself, thus seriously affecting the performance of the lithium-ion battery. In extreme cases, the lithium-ion battery will explode, causing personal safety and property losses.

[0003] Traditional battery thermal management methods mainly include forced air cooling and liquid cooling. Forced air cooling is not suitable for large-scale lithium-ion battery modules in new energy electric vehicles due to its low cooling efficiency and large temperature difference between the inlet and outlet. While using the liquid cooling method to dissipate heat from the lithium-ion battery module, the liquid cooling method has high heat dissipation efficiency, but its assembly system is complex, the coolant has a leakage risk and it is not easy to repair as a whole; in addition, since the layout of the liquid cooling pipes is generally at the bottom of the battery module, the over-concentrated heat dissipation area will further increase the temperature difference inside the middle battery.

[0004] As a new type of battery thermal management method in recent years, organic phase change materials have the advantages of low preparation cost, good temperature uniformity performance, and simple assembly method. At present, a large number of studies have been carried out on the problems of poor leakage resistance, low thermal conductivity, and poor mechanical properties of organic phase change materials, but the flammability problem of organic phase change materials is easily overlooked. Phosphorus-based, nitrogen-based, or silicon-based flame retardants such as melamine, ammonium polyphosphate, and silica are currently the types of flame retardants most commonly used to improve the flame retardancy of phase change materials. Although the problem of toxicity of traditional halogen flame retardants has been eliminated, no matter which series of flame retardants are used, there is a common problem, that is, they can only act on the flame barrier after battery thermal runaway, and cannot achieve the inhibition before battery thermal runaway or extend the time to enter battery thermal runaway. Therefore, how to design and prepare a new type of flame retardant phase change material that can manage the heat of the battery under normal working conditions, effectively inhibit the temperature rise before the battery is about to undergo thermal runaway, and effectively block the spread of the flame after the battery undergoes thermal runaway is one of the keys to the further development of the battery thermal management technology of phase change materials. Summary of the Invention

[0005] The purpose of the present invention is to provide a flame retardant composite phase change material, its preparation method and application.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions: The present invention provides a flame retardant composite phase change material, which includes a phase change material, a polymer, a thermal conductive agent, and a flame retardant; The flame retardant includes hydrated inorganic salts.

[0007] Preferably, by mass percentage, the flame retardant composite phase change material includes: 40-44% of the phase change material, 11-15% of the polymer, 1-2% of the thermal conductive agent, and 44-47% of the flame retardant.

[0008] Preferably, the hydrated inorganic salts include at least one of magnesium chloride hexahydrate, sodium tetraborate decahydrate, potassium alum octadecahydrate, zinc sulfate heptahydrate, and copper sulfate pentahydrate.

[0009] Preferably, the phase change material includes at least one of paraffin, polyethylene glycol, fatty alcohol, fatty acid, and fatty amine.

[0010] Preferably, the polymer includes at least one of a single-component polymer and a two-component polymer; The single-component polymer includes at least one of a single-component epoxy resin and a single-component polyurethane; The two-component polymer includes at least one of a two-component epoxy resin and a two-component polyurethane.

[0011] Preferably, the heat conductive agent includes carbon-based heat conductive agents, and the carbon-based heat conductive agents include at least one of expanded graphite, biochar, carbon black, carbon fiber, carbon nanotubes, and graphene.

[0012] The present invention also provides a preparation method of the flame-retardant composite phase change material described in the above technical solution, including the following steps: Mix the components included in the flame-retardant composite phase change material to obtain the flame-retardant composite phase change material.

[0013] Preferably, when the polymer is a single-component polymer, the mixing includes: Step 1: Mix the molten phase change material and the single-component polymer to obtain a first mixture; Step 2: Mix the first mixture and the heat conductive agent to obtain a second mixture; Step 3: Mix the second mixture and the flame retardant and then cure; When the polymer is a two-component polymer, the mixing includes: Step a: Mix the molten phase change material and polymer A to obtain mixture a; Step b: Mix mixture a and the heat conductive agent to obtain mixture b; Step c: Mix mixture b and the flame retardant to obtain mixture c; Step d: Mix mixture c and polymer B and cure.

[0014] Preferably, in Step 1 and Step a, the melting temperature is 60-80°C; The mixing in Step 1 and the mixing in Step a are independently carried out under stirring conditions, and the stirring speed is 300-500 rpm; The mixing in Step 2 and the mixing in Step b are independently carried out under stirring conditions, the stirring speed is 600-900 rpm, and the stirring time is 60-120 min; The mixing in Step 3 and the mixing in Step c are independently carried out under stirring conditions, the stirring speed is 900-1200 rpm, and the stirring time is 30-60 min; The mixing in Step d is carried out under stirring conditions, the stirring speed is 900-1200 rpm, and the time is 2-3 min; The curing in Step 3 and the curing in Step d are independently at a temperature of 25-40°C and a time of 12-24 h.

[0015] The present invention also provides an application of the flame-retardant composite phase change material described in the above technical solution or the flame-retardant composite phase change material prepared by the preparation method described in the above technical solution in battery thermal management.

[0016] The present invention provides a flame-retardant composite phase change material, which includes a phase change material, a polymer, a heat conductor, and a flame retardant; the flame retardant includes hydrated inorganic salts.

[0017] Compared with the existing composite phase change materials that can be applied to battery thermal management and battery thermal runaway, the advantages of the flame-retardant composite phase change material provided by the present invention are as follows: (1) The flame-retardant composite phase change material provided by the present invention can reversibly absorb heat at 40-55°C (i.e., perform thermal management temperature control on the battery under normal working conditions). Secondly, it can also absorb a large amount of heat generated by the battery before the battery undergoes thermal runaway, that is, it can absorb a large amount of heat in the temperature range of 70-200°C, extending the time of the battery in the second stage of thermal runaway (other flame retardants such as melamine, ammonium polyphosphate, red phosphorus, and other phosphorus-based and nitrogen-based flame retardants do not have the above effects). Moreover, after the battery undergoes thermal runaway, due to its high flame retardancy, this product can also prevent the spread of flames, thereby reducing the safety risk after the battery undergoes thermal runaway.

[0018] (2) The present invention uses hydrated inorganic salts as the flame retardant. In the temperature range of 70-200°C, the flame retardant will gradually lose water molecules when heated, and a large amount of heat will be absorbed during this process, thereby achieving the delay of battery thermal runaway. At the same time, as the temperature rises, the flame retardant will decompose into corresponding oxides when heated, and the generated oxides will cooperate with the heat conductor to form a dense barrier, blocking heat radiation and oxygen diffusion, thereby achieving the purpose of synergistic flame retardancy. The flame retardant provided by the present invention is green and environmentally friendly, and the raw materials have a wide source, low cost, and a simple preparation method, and can be prepared on an industrial scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of the battery module assembled in the test example; Figure 2 It is a DSC curve of the composite material obtained in Example 1; Figure 3 It is a DSC curve of the composite material obtained in Comparative Example 1; Figure 4 It is a temperature curve of the battery module assembled with the composite material obtained in Example 1 during 1C rate charging and 1.5C rate discharging; Figure 5 It is a temperature curve of the battery module assembled with the composite material obtained in Comparative Example 1 during 1C rate charging and 1.5C rate discharging; Figure 6The temperature curves of heating rods No. 1 - 9 of the battery module assembled with the composite material obtained in Example 1 during thermal runaway simulation; Figure 7 The temperature curves of heating rods No. 1 - 9 of the battery module assembled with the composite material obtained in Comparative Example 1 during thermal runaway simulation; Figure 8 The temperature comparison of batteries No. 1 - 9 in the battery modules assembled with the composite materials obtained in Example 1 and Comparative Example 1. Detailed implementation manners

[0020] The present invention provides a flame - retardant composite phase - change material, which comprises a phase - change material, a polymer, a heat - conducting agent and a flame retardant; The flame retardant comprises hydrated inorganic salts.

[0021] In the present invention, by mass percentage, the flame - retardant composite phase - change material preferably comprises: 40 - 44% of the phase - change material, 11 - 15% of the polymer, 1 - 2% of the heat - conducting agent and 44 - 47% of the flame retardant.

[0022] By mass percentage, the flame - retardant composite phase - change material provided by the present invention preferably comprises 40 - 44% of the phase - change material, specifically it can be 40%, 41%, 42%, 43%, 44%. In the present invention, the phase - change material preferably comprises at least one of paraffin wax, polyethylene glycol, fatty alcohol, fatty acid and fatty amine; the fatty alcohol preferably comprises at least one of tetradecanol and hexadecanol; the fatty acid preferably comprises at least one of tetradecanoic acid and hexadecanoic acid; the fatty amine preferably comprises at least one of tetradecylamine and hexadecylamine; the polyethylene glycol preferably comprises at least one of polyethylene glycol 1500 and polyethylene glycol 2000, and the paraffin wax preferably comprises at least one of paraffin wax No. 48 and paraffin wax No. 50. In the present invention, the phase - change temperature of the phase - change material is preferably 48 - 52 °C.

[0023] By mass percentage, the flame - retardant composite phase - change material provided by the present invention preferably comprises 11 - 15% of the polymer, specifically it can be 11%, 12%, 13%, 14%, 15%. In the present invention, the polymer preferably comprises at least one of a single - component polymer and a two - component polymer; the single - component polymer preferably comprises at least one of a single - component epoxy resin and a single - component polyurethane; the two - component polymer preferably comprises at least one of a two - component epoxy resin and a two - component polyurethane. In a specific embodiment of the present invention, the polymer is a two - component epoxy resin, namely epoxy resin AB glue, and the specific model is epoxy resin E - 44. In the present invention, the polymer can provide an adsorption effect for the phase - change material during solid - liquid phase change, improve the overall thermal stability of the composite material and prevent the leakage of the liquid phase - change material.

[0024] In terms of mass percentage, the flame-retardant composite phase change material provided by the present invention preferably includes 1-2% of a heat-conducting agent, specifically 1%, 1.5%, or 2%. In the present invention, the heat-conducting agent preferably includes a carbon-based heat-conducting agent, and the carbon-based heat-conducting agent preferably includes at least one of expanded graphite, biochar, carbon black, carbon fiber, carbon nanotubes, and graphene; the biochar preferably includes at least one of wood-derived biochar, straw-derived biochar, and fruit shell-derived biochar. In the present invention, the heat-conducting agent not only acts as a heat-conducting enhancer but also plays a synergistic flame-retardant role with the flame retardant, and can act as a carbon source during the combustion of the product and form a dense carbon layer on its surface, thereby achieving a flame-retardant effect.

[0025] In terms of mass percentage, the flame-retardant composite phase change material provided by the present invention preferably includes 44-47% of a flame retardant, specifically 44%, 45%, 46%, or 47%. In the present invention, the flame retardant includes hydrated inorganic salts, and the hydrated inorganic salts preferably include at least one of magnesium chloride hexahydrate, sodium tetraborate decahydrate, potassium aluminum sulfate octadecahydrate, zinc sulfate heptahydrate, and copper sulfate pentahydrate.

[0026] The present invention also provides a preparation method of the flame-retardant composite phase change material described in the above technical solution, including the following steps: Mix the components included in the flame-retardant composite phase change material to obtain the flame-retardant composite phase change material.

[0027] In the present invention, when the polymer is a single-component polymer, the mixing preferably includes: Step 1: Mix the melted phase change material and the single-component polymer to obtain a first mixture; Step 2: Mix the first mixture and the heat-conducting agent to obtain a second mixture; Step 3: Mix the second mixture and the flame retardant and then cure.

[0028] In the present invention, in Step 1, the melting temperature is preferably 60-80°C. In the present invention, the mixing is preferably carried out under stirring, and the stirring speed is preferably 300-500 rpm.

[0029] In the present invention, in Step 2, the mixing order is preferably to slowly add the heat-conducting agent to the first mixture; the mixing is preferably carried out under stirring, the stirring speed is preferably 600-900 rpm, and the stirring time after adding the heat-conducting agent is preferably 60-120 min.

[0030] In the present invention, in the step 3, the order of mixing is preferably to slowly add the flame retardant to the second mixture; the mixing is preferably carried out under stirring conditions, the rotation speed of the stirring is preferably 900 - 1200 rpm, and the stirring time after adding the flame retardant is preferably 30 - 60 min.

[0031] In the present invention, before curing, it is also preferably to place the obtained mixed system in a corresponding mold. In the present invention, the curing temperature is preferably 25 - 40 °C, and the time is preferably 12 - 24 h.

[0032] In the present invention, when the polymer is a two-component polymer, the mixing preferably includes: Step a: Mix the melted phase change material and polymer A to obtain mixture a; Step b: Mix the mixture a and the heat conductive agent to obtain mixture b; Step c: Mix the mixture b and the flame retardant to obtain mixture c; Step d: Mix the mixture c and polymer B for curing.

[0033] In the present invention, in the step a, the condition parameters of melting and mixing are preferably the same as those in the step 1, which will not be elaborated here.

[0034] In the present invention, in the step b, the condition parameters of mixing are preferably the same as those in the step 2, which will not be elaborated here.

[0035] In the present invention, in the step c, the condition parameters of mixing are preferably the same as those in the step 3, which will not be elaborated here.

[0036] In the present invention, in the step d, the mixing is preferably carried out under stirring conditions, the rotation speed of the stirring is preferably 900 - 1200 rpm, and the time is preferably 2 - 3 min. In the present invention, in the step d, the condition parameters of curing are preferably the same as those in the step 3, which will not be elaborated here.

[0037] The present invention also provides the application of the flame retardant composite phase change material described in the above technical solution or the flame retardant composite phase change material prepared by the preparation method described in the above technical solution in battery thermal management.

[0038] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0039] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Example 1 Weigh 44 parts of paraffin wax and place it in an oil bath at 65 °C for melting; After the paraffin wax is completely melted, add 5.5 parts of epoxy resin A glue (specific model: epoxy resin E-44) and mechanically stir at a speed of 300 rpm until the solution is uniform to obtain mixture a; Then, add 1 part of expanded graphite to mixture a in batches slowly. At the same time, as the expanded graphite is added, gradually increase the speed of the mechanical stirrer to 600 rpm. After the expanded graphite is completely added, mechanically stir at a speed of 600 rpm for 60 min to obtain mixture b; Add 44 parts of magnesium chloride hexahydrate to mixture b in batches slowly and gradually increase the speed to 900 rpm. After the magnesium chloride hexahydrate is completely added, mechanically stir at a speed of 900 rpm for 30 min to obtain mixture c; Add 5.5 parts of epoxy resin B glue to the obtained mixture c, stir for 2 min, then load it into the corresponding mold and cure it in an oven at 40 °C for 24 h to obtain the flame-retardant composite phase change material.

[0041] Example 2 Prepare the flame-retardant composite phase change material in the same way as in Example 1, except that the paraffin wax is replaced by myristyl alcohol.

[0042] Example 3 Prepare the flame-retardant composite phase change material in the same way as in Example 1, except that the magnesium chloride hexahydrate is replaced by sodium tetraborate decahydrate.

[0043] Example 4 Prepare the flame-retardant composite phase change material in the same way as in Example 1, except that the expanded graphite is 2 parts and the magnesium chloride hexahydrate is 43 parts.

[0044] Example 5 Prepare the flame-retardant composite phase change material in the same way as in Example 1, except that the expanded graphite is replaced by platycodon-derived biochar.

[0045] Comparative Example 1 Prepare the flame-retardant composite phase change material in the same way as in Example 1, except that the magnesium chloride hexahydrate is replaced by ammonium polyphosphate.

[0046] Performance Test Test Example 1 The composite materials obtained in Example 1 and Comparative Example 1 were tested by a differential scanning calorimeter, and the test results are as follows Figure 2 and Figure 3 shown below, where Figure 2 is the DSC curve of the composite material obtained in Example 1, Figure 3 is the DSC curve of the composite material obtained in Comparative Example 1; the specific test results are shown in Table 1; Table 1 DSC curve results of the composite materials obtained in Example 1 and Comparative Example 1

[0047] It can be seen from the above test results that when the battery module is charged and discharged under normal working conditions, the reversible phase change latent heat provided by paraffin (78.6 J / g) can effectively control the temperature of the battery module, keeping the maximum temperature and maximum temperature difference of the battery module within the safe working temperature range; when the battery module malfunctions and the temperature exceeds the safe working temperature range, the decomposition heat provided by the inorganic hydrated salt in Example 1 can absorb a large amount of heat, delaying or even suppressing the occurrence of thermal runaway.

[0048] Test Example 2 The composite materials obtained in the examples and comparative examples were used as test samples for battery thermal management simulation tests; The composite materials obtained in the examples and comparative examples were modules with a length, width, and height of 90×90×65 mm. Nine cylindrical holes with a diameter of 26 mm were drilled at equal distances by a hole drilling machine, and nine 26650 cylindrical batteries were embedded in the corresponding holes to assemble a 3S3P battery module for charge and discharge tests. The temperature changes during the charge and discharge process were monitored with thermocouples. The schematic diagram of the test device is as follows Figure 1 shown below.

[0049] Figure 4 is the temperature curve of the battery module assembled with the composite material obtained in Example 1 during 1C rate charging and 1.5C rate discharging; Figure 5 is the temperature curve of the battery module assembled with the composite material obtained in Comparative Example 1 during 1C rate charging and 1.5C rate discharging; the specific test results are shown in Table 2: Table 2 Temperature changes during the charge and discharge of the batteries assembled with the composite materials of Example 1 and Comparative Example 1

[0050] As can be seen from the above tests, the battery module was subjected to 5 charge-discharge cycles at a charge-discharge rate of 1C to 1.5C. During this process, the highest temperature and the maximum temperature difference of the battery module were 50.49°C and 2.45°C, respectively, both within the safe operating temperature range of the battery, demonstrating that the composite phase change material of Example 1 has excellent temperature control effect on the battery module under normal working conditions.

[0051] Test Example 3 Referring to Test Example 2, a 90×90×65 mm module containing 9 holes with a diameter of 26 mm was prepared in the same way. Nine heating rods with a diameter of 26 mm were embedded in the corresponding holes for the battery thermal runaway simulation test. The specific test process is as follows: The central heating rod was heated with a power of 30 W through a DC power supply, and at the same time, the temperature changes of the heating rod and the surrounding heating rods were monitored with thermocouples.

[0052] Figure 6 Temperature curves of heating rods No. 1-9 during thermal runaway simulation of the battery module assembled with the composite material obtained in Example 1; Figure 7 Temperature curves of heating rods No. 1-9 during thermal runaway simulation of the battery module assembled with the composite material obtained in Comparative Example 1; Figure 8 Temperature comparison of batteries No. 1-9 in the battery modules assembled with the composite materials obtained in Example 1 and Comparative Example 1; The specific test results are shown in Table 3; Table 3 Temperature changes of the composite materials obtained in Example 1 and Comparative Example 1 in the battery module

[0053] As can be seen from the above test results, the temperature of each heating rod in Example 1 is lower than that of the corresponding heating rod in Comparative Example 1. This is mainly due to the fact that inorganic hydrated salts can absorb a large amount of heat through the decomposition of crystal water at medium and high temperatures, inhibiting the rapid rise of battery temperature. This endothermic ability at medium and high temperatures is not possessed by traditional flame retardants such as ammonium polyphosphate.

[0054] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all embodiments. Other embodiments can be obtained according to this embodiment without creative work, and these embodiments all belong to the protection scope of the present invention.

Claims

1. A flame-retardant composite phase change material, characterized in that, It includes a phase change material, a polymer, a thermal conductive agent, and a flame retardant; The flame retardant includes hydrated inorganic salts.

2. The flame-retardant composite phase change material according to claim 1, wherein In terms of mass percentage, the flame retardant composite phase change material includes: 40 - 44% of the phase change material, 11 - 15% of the polymer, 1 - 2% of the thermal conductive agent, and 44 - 47% of the flame retardant.

3. The flame-retardant composite phase change material according to claim 1 or 2, characterized in that, The hydrated inorganic salts include at least one of magnesium chloride hexahydrate, sodium tetraborate decahydrate, potassium alum octadecahydrate, zinc sulfate heptahydrate, and copper sulfate pentahydrate.

4. The flame-retardant composite phase change material according to claim 1 or 2, wherein The phase change material includes at least one of paraffin, polyethylene glycol, fatty alcohol, fatty acid, and fatty amine.

5. The flame-retardant composite phase change material according to claim 1 or 2, characterized in that, The polymer includes at least one of a single - component polymer and a two - component polymer; The single - component polymer includes at least one of a single - component epoxy resin and a single - component polyurethane; The two - component polymer includes at least one of a two - component epoxy resin and a two - component polyurethane.

6. The flame-retardant composite phase change material according to claim 1, wherein The thermal conductive agent includes a carbon - based thermal conductive agent, and the carbon - based thermal conductive agent includes at least one of expanded graphite, biochar, carbon black, carbon fiber, carbon nanotube, and graphene.

7. The preparation method of the flame-retardant composite phase change material according to any one of claims 1 to 6, characterized in that, It includes the following steps: Mix the components included in the flame retardant composite phase change material to obtain the flame retardant composite phase change material.

8. The preparation method according to claim 7, characterized in that, When the polymer is a single - component polymer, the mixing includes: Step 1: Mix the melted phase change material and the single - component polymer to obtain a first mixture; Step 2: Mix the first mixture and the thermal conductive agent to obtain a second mixture; Step 3: Mix the second mixture and the flame retardant and then cure. When the polymer is a two - component polymer, the mixing includes: Step a: Mix the melted phase change material and polymer A to obtain mixture a; Step b: Mix mixture a and the thermal conductive agent to obtain mixture b; Step c: Mix mixture b and the flame retardant to obtain mixture c; Step d: Mix mixture c and polymer B and cure.

9. The preparation method according to claim 8, characterized in that, In Step 1 and Step a, the melting temperature is 60 - 80°C; The mixing in Step 1 and the mixing in Step a are independently carried out under stirring conditions, and the stirring speed is 300 - 500 rpm; The mixing in Step 2 and the mixing in Step b are independently carried out under stirring conditions, the stirring speed is 600 - 900 rpm, and the stirring time is 60 - 120 min; The mixing in Step 3 and the mixing in Step c are independently carried out under stirring conditions, the stirring speed is 900 - 1200 rpm, and the stirring time is 30 - 60 min; The mixing in Step d is carried out under stirring conditions, the stirring speed is 900 - 1200 rpm, and the time is 2 - 3 min; The curing temperature in Step 3 and the curing temperature in Step d are independently 25 - 40°C, and the curing time is independently 12 - 24 h.

10. Use of the flame-retardant composite phase change material according to any one of claims 1 to 6 or the flame-retardant composite phase change material prepared by the preparation method according to any one of claims 7 to 9 in battery thermal management.

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