Intrinsic flame-retardant solid-solid phase change material, preparation method thereof, battery module and application thereof

Abstract

The present application relates to the technical field of organic phase change material, and more particularly to an intrinsic flame-retardant solid-solid phase change material, a preparation method thereof, a battery module and application thereof.The preparation raw material of the intrinsic flame-retardant solid-solid phase change material comprises a boron phosphate ester of a phase change substance with a hydroxyl group, expanded graphite, an amino-containing flame retardant and an isocyanate compound; and the preparation raw material of the boron phosphate ester of the phase change substance with a hydroxyl group comprises a phase change substance with a hydroxyl group, boric acid and diphosphorus pentoxide.The intrinsic flame-retardant solid-solid phase change material has the advantages of flame retardation, mechanics and thermal stability.

Description

Technical Field

[0001] This invention relates to the field of organic phase change materials technology, and in particular to an intrinsically flame-retardant solid-solid phase change material, its preparation method, battery module, and its application. Background Technology

[0002] With the increasing power of electronic devices and the large-scale development of energy storage systems, organic phase change materials (PCMs) have attracted much attention in the field of temperature control due to their efficient thermal management capabilities. However, traditional solid-liquid PCMs are prone to liquid phase leakage during the phase change process, and are susceptible to support framework collapse and combustion risks under high temperatures or thermal shock, severely restricting their application in scenarios with stringent safety requirements such as electric vehicle battery packs and energy storage power stations. To address the leakage problem, solid-solid PCMs restrict the phase change volume change through intermolecular forces or crystal structure, but their rigid framework often leads to high material brittleness and insufficient thermal cycling adaptability, making it difficult to meet the dynamic thermal management requirements of flexible devices. In addition, existing flame-retardant modifications mostly rely on physically blended flame retardants, which are prone to migration and aggregation due to poor interfacial compatibility, resulting in uncontrollable degradation of flame-retardant performance; while the inherent flammability of traditional support matrices such as epoxy resin further exacerbates the high-temperature safety risks of the material. Therefore, there is an urgent need to develop a PCM that balances flame retardancy, mechanical properties, and thermal stability. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide an intrinsic flame-retardant solid-solid phase change material and its preparation method, a battery module and its application. The intrinsic flame-retardant solid-solid phase change material of the present invention has the advantages of flame retardancy, mechanical and thermal stability.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides an intrinsically flame-retardant solid-solid phase change material, the raw materials for which include: borate phosphate ester containing hydroxyl groups, expanded graphite, an amino-containing flame retardant, and isocyanate compounds;

[0006] The raw materials for preparing the borate phosphate ester of the phase change material with hydroxyl groups include the phase change material with hydroxyl groups, boric acid, and phosphorus pentoxide.

[0007] The molar ratio of the hydroxyl-containing phase change material, boric acid, and phosphorus pentoxide is 6:(1.8~2.2):(2.8~3.2).

[0008] The mass ratio of borate phosphate ester to expanded graphite in the phase change material with hydroxyl groups is (60~80):(1~3).

[0009] The mass ratio of the borate phosphate ester of the phase change material with hydroxyl groups to the amino-containing flame retardant is (70~86):(5~16).

[0010] The mass ratio of borate phosphate ester and isocyanate compound in the phase change material with hydroxyl groups is (70~86):(8~20).

[0011] Preferably, the phase change material containing hydroxyl groups includes one or more of polyethylene glycol, hexadecyl alcohol, tetradecyl alcohol, and octadecyl alcohol;

[0012] The polyethylene glycol includes one or more of polyethylene glycol 1500, polyethylene glycol 2000, and polyethylene glycol 4000.

[0013] Preferably, the isocyanate compound includes one or more of diphenylmethane diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenyl polyisocyanate.

[0014] This invention also provides a method for preparing the intrinsically flame-retardant solid-solid phase change material described in the above technical solution, comprising the following steps:

[0015] The molten phase change material with hydroxyl groups is first mixed with boric acid and subjected to a first esterification condensation reaction, and then mixed with phosphorus pentoxide and subjected to a second esterification condensation reaction to obtain borate phosphate ester of the phase change material with hydroxyl groups.

[0016] The borate phosphate of the phase change material containing hydroxyl groups is melted and then mixed sequentially with expanded graphite and an amino-containing flame retardant to carry out a grafting reaction, thereby obtaining a second phase change material grafted with an amino-containing flame retardant.

[0017] The second phase change material grafted with an amino-containing flame retardant is mixed with an isocyanate compound and then cured to obtain the intrinsic flame-retardant solid-solid phase change material.

[0018] Preferably, the first esterification condensation reaction is carried out under stirring conditions;

[0019] The temperature of the first esterification condensation reaction is 140~170℃, and the time is 5~8h.

[0020] Preferably, the second esterification condensation reaction is carried out under stirring conditions;

[0021] The second esterification condensation reaction is carried out at a temperature of 90~130℃ for 2~3 hours.

[0022] Preferably, the process of mixing with expanded graphite further includes a first stirring;

[0023] The first stirring speed is 400~800 rpm, and the time is 1~2 hours.

[0024] Preferably, the mixture with the amino-containing flame retardant further includes a second stirring step;

[0025] The second stirring speed is 600~1000 rpm, and the time is 0.5~1h.

[0026] This invention provides a battery module, including a battery module and a phase change material skeleton;

[0027] The material of the phase change material skeleton is the intrinsic flame-retardant solid-solid phase change material described in the above technical solution or the intrinsic flame-retardant solid-solid phase change material prepared by the preparation method described in the above technical solution.

[0028] The present invention also provides the application of the battery module described above in energy storage devices and electric vehicles.

[0029] This invention provides an intrinsically flame-retardant solid-solid phase change material, the raw materials for which include: borate phosphate ester containing hydroxyl-containing phase change material, expanded graphite, amino-containing flame retardant, and isocyanate compound; the raw materials for preparing the borate phosphate ester containing hydroxyl-containing phase change material include hydroxyl-containing phase change material, boric acid, and phosphorus pentoxide; the molar ratio of the hydroxyl-containing phase change material, boric acid, and phosphorus pentoxide is 6:(1.8~2.2):(2.8~3.2); the mass ratio of the borate phosphate ester containing hydroxyl-containing phase change material to expanded graphite is (60~80):(1~3); the mass ratio of the borate phosphate ester containing hydroxyl-containing phase change material to amino-containing flame retardant is (70~86):(5~16); and the mass ratio of the borate phosphate ester containing hydroxyl-containing phase change material to isocyanate compound is (70~86):(8~20). The hydroxyl-containing phase change material in the raw materials of this invention can undergo esterification condensation reaction with phosphorus pentoxide and boric acid to generate a borate phosphate phase change material with phosphorus-based and boron-based flame-retardant groups. The borate phosphate bonds generated by the condensation reaction realize the flame-retardant functionalization of the molecular chain. Simultaneously, due to the porous layered structure of expanded graphite, it has a strong adsorption effect, stabilizing the phase change system through physical confinement and constructing a synergistic flame-retardant mechanism by utilizing the barrier properties of graphite sheets. The amino-containing flame retardant in the expanded graphite... The enrichment process significantly increases the local concentration of hydroxyl functional groups in borate phosphate phase change materials containing phosphorus and boron flame-retardant groups, promoting efficient condensation reactions between hydroxyl and amino groups to form a chemical bond structure with synergistic phosphorus-nitrogen flame-retardant effects. Finally, isocyanate compounds have a cross-linking and curing effect, enabling the construction of a three-dimensional cross-linked polyurethane network structure between molecules. This flexible polymer matrix not only endows the material with excellent deformation adaptability, but its hard-segment-soft-segment microphase separation characteristics can also optimize the phase change energy storage performance. Attached Figure Description

[0030] Figure 1 The leakage resistance test results are those of the intrinsic flame-retardant solid-solid phase change material described in Example 1.

[0031] Figure 2 The leakage resistance test results are those of the intrinsic flame-retardant solid-solid phase change material described in Example 2.

[0032] Figure 3 The leakage resistance test results are for the intrinsic solid-solid phase change material described in Example 3;

[0033] Figure 4 The flexible characterization structure of the intrinsic flame-retardant solid-solid phase change material described in Example 1 and Comparative Example 2;

[0034] Figure 5 The image shows a vertical combustion test image of the intrinsic flame-retardant solid-solid phase change material described in Example 1.

[0035] Figure 6 The image shows a vertical combustion test image of the intrinsic flame-retardant solid-solid phase change material described in Comparative Example 1.

[0036] Figure 7 The image shows a vertical combustion test image of the intrinsic flame-retardant solid-solid phase change material described in Comparative Example 2.

[0037] Figure 8 The thermal management effect of the intrinsic flame-retardant solid-solid phase change materials described in Example 1 and Comparative Examples 1-2 is shown. Detailed Implementation

[0038] This invention provides an intrinsically flame-retardant solid-solid phase change material, the raw materials for which include: borate phosphate ester containing hydroxyl groups, expanded graphite, an amino-containing flame retardant, and isocyanate compounds;

[0039] The raw materials for preparing the borate phosphate ester of the phase change material with hydroxyl groups include the phase change material with hydroxyl groups, boric acid, and phosphorus pentoxide.

[0040] The molar ratio of the hydroxyl-containing phase change material, boric acid, and phosphorus pentoxide is 6:(1.8~2.2):(2.8~3.2).

[0041] The mass ratio of borate phosphate ester to expanded graphite in the phase change material with hydroxyl groups is (60~80):(1~3).

[0042] The mass ratio of the borate phosphate ester of the phase change material with hydroxyl groups to the amino-containing flame retardant is (70~86):(5~16).

[0043] The mass ratio of borate phosphate ester and isocyanate compound in the phase change material with hydroxyl groups is (70~86):(8~20).

[0044] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0045] In this invention, the raw materials for preparing the intrinsic flame-retardant solid-solid phase change material include borate phosphate ester, a phase change substance with hydroxyl groups.

[0046] In this invention, the raw materials for preparing the borate phosphate ester of the phase change material with hydroxyl groups include the phase change material with hydroxyl groups, boric acid, and phosphorus pentoxide.

[0047] In this invention, the molar ratio of the hydroxyl-containing phase change material, boric acid, and phosphorus pentoxide is 6:(1.8~2.2):(2.8~3.2), preferably 6:2:3.

[0048] In this invention, the hydroxyl-containing phase change material preferably includes one or more of polyethylene glycol, hexadecyl alcohol, tetradecyl alcohol, and octadecyl alcohol, wherein the molecular weight of the polyethylene glycol is preferably 1000-4000; the polyethylene glycol preferably includes one or more of polyethylene glycol 1500, polyethylene glycol 2000, and polyethylene glycol 4000; when the hydroxyl-containing phase change material is two or more of the above-mentioned specific selections, this invention does not impose any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In an embodiment of this invention, the hydroxyl-containing phase change material is specifically polyethylene glycol 2000.

[0049] In this invention, the method for preparing the borate phosphate ester of the phase change material with hydroxyl groups preferably includes the following steps:

[0050] The molten phase change material with hydroxyl groups is first mixed with boric acid and subjected to a first esterification condensation reaction, and then mixed with phosphorus pentoxide and subjected to a second esterification condensation reaction to obtain borate phosphate ester of the phase change material with hydroxyl groups.

[0051] The present invention does not impose any special limitations on the preparation of the molten phase change material containing hydroxyl groups; a heating and melting process well known to those skilled in the art can be used.

[0052] In this invention, the first mixing is preferably performed by adding boric acid to the molten phase change material containing hydroxyl groups; in this invention, the process of adding boric acid is preferably carried out under stirring conditions; this invention does not impose any special limitations on the method of adding boric acid, and any method known to those skilled in the art can be used.

[0053] In this invention, the first esterification condensation reaction is preferably carried out under stirring conditions. The temperature of the first esterification condensation reaction is preferably 140~170℃, more preferably 140℃, 145℃, 150℃, 155℃, 160℃, 165℃ or 170℃; the time is preferably 5~8h, more preferably 5h, 5.5h, 6h, 6.5h, 7h, 7.5h or 8h. The stirring speed is preferably 400~800rpm, more preferably 600rpm, 700rpm or 800rpm. In an embodiment of this invention, the temperature of the first esterification condensation reaction can be 160℃, the time can be 6h, and the stirring speed can be 700rpm.

[0054] In this invention, the mixing with phosphorus pentoxide is preferably carried out under stirring conditions, by adding phosphorus pentoxide to the product system obtained after the first esterification condensation reaction is completed. This invention does not impose any special limitations on the method of adding phosphorus pentoxide, and any method known to those skilled in the art can be used.

[0055] In this invention, the second esterification condensation reaction is preferably carried out under stirring conditions, wherein the stirring speed is preferably 600-1000 rpm, more preferably 800 rpm, 900 rpm, or 1000 rpm; the temperature of the second esterification condensation reaction is preferably 90-130°C, more preferably 110°C, 120°C, or 130°C; and the time of the second esterification condensation reaction is preferably 2-3 hours, more preferably 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, or 3 hours. In an embodiment of this invention, the stirring speed of the second esterification condensation reaction can be 800 rpm, the temperature can be 130°C, and the time can be 3 hours.

[0056] In this invention, the mass ratio of the borate phosphate ester and expanded graphite of the hydroxyl-containing phase change material is (60~80):(1~3), preferably (65~75):(1.5~2.5). In embodiments of this invention, the mass ratio of the borate phosphate ester and expanded graphite of the hydroxyl-containing phase change material can be 78:1 or 78:2.

[0057] In this invention, the mass ratio of the borate phosphate ester of the phase change material with hydroxyl groups to the amino-containing flame retardant is (70~86):(5~16); in the embodiments of this invention, the mass ratio of the borate phosphate ester of the phase change material with hydroxyl groups to the amino-containing flame retardant is specifically 78:8, 78:5 or 78:11.

[0058] In this invention, the amino-containing flame retardant is preferably melamine and / or melamine phosphate. When the amino-containing flame retardant is melamine and melamine phosphate, this invention does not impose any special limitation on the ratio of melamine and melamine phosphate; they can be mixed in any ratio. In embodiments of this invention, the amino-containing flame retardant can be melamine.

[0059] In this invention, the isocyanate compound preferably includes one or more of diphenylmethane diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenyl polyisocyanate. When the isocyanate compound is two or more of the above-mentioned specific selections, this invention does not have any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In the embodiments of this invention, the isocyanate compound can be diphenylmethane diisocyanate.

[0060] In this invention, the mass ratio of the borate phosphate ester and isocyanate compound of the phase change material with hydroxyl groups is (70~86):(8~20), preferably (75~80):(10~15). In embodiments of this invention, the mass ratio of the borate phosphate ester and isocyanate compound of the phase change material with hydroxyl groups can be 78:8, 78:11, or 78:5.

[0061] This invention also provides a method for preparing the intrinsically flame-retardant solid-solid phase change material described in the above technical solution, comprising the following steps:

[0062] The molten phase change material with hydroxyl groups is first mixed with boric acid and subjected to a first esterification condensation reaction, and then mixed with phosphorus pentoxide and subjected to a second esterification condensation reaction to obtain borate phosphate ester of the phase change material with hydroxyl groups.

[0063] The borate phosphate of the phase change material containing hydroxyl groups is melted and then mixed sequentially with expanded graphite and an amino-containing flame retardant to carry out a grafting reaction, thereby obtaining a second phase change material grafted with an amino-containing flame retardant.

[0064] The second phase change material grafted with an amino-containing flame retardant is mixed with an isocyanate compound and then cured to obtain the intrinsic flame-retardant solid-solid phase change material.

[0065] In this invention, a molten phase change material with hydroxyl groups is first mixed with boric acid to undergo a first esterification condensation reaction, and then mixed with phosphorus pentoxide to undergo a second esterification condensation reaction to obtain a borate phosphate ester of the phase change material with hydroxyl groups.

[0066] In this invention, the preparation method of the borate phosphate of the phase change material with hydroxyl groups is preferably the same as the preparation method described in the above technical solution, and will not be repeated here.

[0067] After obtaining the borate phosphate ester of the phase change material containing hydroxyl groups, the present invention melts the borate phosphate ester of the phase change material containing hydroxyl groups and mixes it sequentially with expanded graphite and an amino-containing flame retardant to carry out a grafting reaction, thereby obtaining a second phase change material grafted with an amino-containing flame retardant.

[0068] The present invention does not impose any special limitations on the melting process; any process well known to those skilled in the art can be used.

[0069] In this invention, the mixing process with expanded graphite is preferably carried out by adding expanded graphite to the molten borate phosphate ester containing hydroxyl groups. This invention does not impose any special limitations on the method or process of adding the expanded graphite; any method or process well known to those skilled in the art can be used. After mixing with expanded graphite, the process preferably includes a first stirring, wherein the stirring speed is preferably 400-800 rpm, more preferably 600-800 rpm; and the stirring time is preferably 1-2 hours, more preferably 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, or 2 hours. In an embodiment of this invention, the stirring speed can be 700 rpm, and the stirring time can be 2 hours.

[0070] In this invention, the mixing process with the amino-containing flame retardant is preferably performed by adding the amino-containing flame retardant to the system obtained after the first stirring. This invention does not impose any special limitations on the method or process of adding the amino-containing flame retardant; any method or process well-known to those skilled in the art can be used. After mixing with the amino-containing flame retardant, a second stirring is also preferably performed. The stirring speed of the second stirring is preferably 600-1000 rpm, more preferably 800-1000 rpm; the stirring time of the second stirring is preferably 0.5-1 hour, more preferably 1 hour. In an embodiment of this invention, the stirring speed of the second stirring can be 700 rpm, and the stirring time can be 1 hour. In this invention, the second stirring process is the grafting reaction process.

[0071] After obtaining the second phase change material grafted with the amino-containing flame retardant, the present invention mixes the second phase change material grafted with the amino-containing flame retardant with an isocyanate compound and then solidifies it to obtain the intrinsic flame-retardant solid-solid phase change material.

[0072] In this invention, the mixing of the second phase change material grafted with an amino-containing flame retardant and the isocyanate compound is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring process, and any process well known to those skilled in the art can be used.

[0073] In this invention, the curing temperature is preferably 50~100℃, more preferably 60℃, 70℃ or 80℃, and the curing time is preferably 0.5~1h, more preferably 1h. In an embodiment of this invention, the curing temperature can be 70℃ and the curing time can be 1h.

[0074] Taking polyethylene glycol (PEG) as the hydroxyl-containing phase change material and melamine as the amino-containing flame retardant as an example, the preparation method of this invention involves fully reacting molten PEG with boric acid and phosphorus pentoxide, then adding expanded graphite to enrich the molten PEG borate phosphate, and finally adding melamine to react fully with it, thus synthesizing an intrinsic flame-retardant phase change material. In this intrinsic flame-retardant phase change material, the PEG segments provide latent heat properties, and the incorporation of phosphate groups and melamine imparts flame-retardant properties. Simultaneously, melamine grafting forms a melamine-PEG borate phosphate resin, and the addition of diphenylmethane diisocyanate generates a high-molecular-weight polyurethane, providing flexibility to this composite phase change material.

[0075] This invention provides a battery module, including a battery module and a phase change material skeleton;

[0076] The material of the phase change material skeleton is the intrinsic flame-retardant solid-solid phase change material described in the above technical solution or the intrinsic flame-retardant solid-solid phase change material prepared by the preparation method described in the above technical solution.

[0077] The present invention does not impose any special limitations on the battery module; any battery module well known to those skilled in the art can be used.

[0078] This invention also provides the application of the battery module described above in energy storage devices and electric vehicles. This invention does not impose any special limitations on the methods used in these applications; methods well-known to those skilled in the art can be employed.

[0079] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0080] Example 1

[0081] 100g of polyethylene glycol 2000 was poured into a magnetic stirring oil bath at 70℃ and heated until completely melted. Boric acid (the molar ratio of boric acid to polyethylene glycol is 1:3) was added at 160℃ and 700rpm and stirred continuously for 6 hours. Phosphorus pentoxide (the molar ratio of phosphorus pentoxide to polyethylene glycol 2000 is 1:2) was added at 700rpm and 130℃ and stirred continuously for 2 hours to obtain borate phosphate ester, a phase change material with hydroxyl groups.

[0082] 78g of borate phosphate of the phase change material containing hydroxyl groups was added to an oil bath at 80°C and melted. Then, 2g of expanded graphite was added and stirred at 700rpm for 2 hours until homogeneous. Next, 8g of melamine was added and stirred at 700rpm for 1 hour. Then, 8g of diphenylmethane diisocyanate was added and stirred until stirring was no longer possible. The mixture was then kept at the temperature and allowed to stand for 1 hour until the reaction was complete. The mixture was poured into a mold and cross-linked and cured at 70°C to obtain the intrinsic flame-retardant solid-solid phase change material.

[0083] Example 2

[0084] 100g of polyethylene glycol 2000 was poured into a magnetic stirring oil bath at 70℃ and heated until completely melted. Boric acid (the molar ratio of boric acid to polyethylene glycol is 1:3) was added at 160℃ and 700rpm and stirred continuously for 6 hours. Phosphorus pentoxide (the molar ratio of phosphorus pentoxide to polyethylene glycol 2000 is 1:2) was added at 700rpm and 130℃ and stirred continuously for 2 hours to obtain borate phosphate ester, a phase change material with hydroxyl groups.

[0085] 78g of borate phosphate of the hydroxyl-containing phase change material was melted in an oil bath at 80°C, followed by the addition of 2g of expanded graphite. The mixture was stirred at 700rpm for 2 hours until homogeneous. Then, 5g of melamine was added and stirred at 700rpm for 1 hour. Finally, 11g of diphenylmethane diisocyanate was added and stirred until stirring ceased. The mixture was then allowed to stand at the set temperature for 1 hour until the reaction was complete. The mixture was poured into a mold and cross-linked and cured at 70°C to obtain the intrinsic flame-retardant solid-solid phase change material.

[0086] Example 3

[0087] 100g of polyethylene glycol 2000 was poured into a magnetic stirring oil bath at 70℃ and heated until completely melted. Boric acid (the molar ratio of boric acid to polyethylene glycol is 1:3) was added at 160℃ and 700rpm and stirred continuously for 6 hours. Phosphorus pentoxide (the molar ratio of phosphorus pentoxide to polyethylene glycol 2000 is 1:2) was added at 700rpm and 130℃ and stirred continuously for 2 hours to obtain borate phosphate ester, a phase change material with hydroxyl groups.

[0088] 78g of borate phosphate of the phase change material containing hydroxyl groups was added to an oil bath at 80°C and melted. Then, 2g of expanded graphite was added and stirred at 700rpm for 2 hours until homogeneous. Next, 11g of melamine was added and stirred at 700rpm for 1 hour. Then, 5g of diphenylmethane diisocyanate was added and stirred continuously until stirring failed. The mixture was then kept at the temperature and allowed to stand for 1 hour until the reaction was complete. The mixture was poured into a mold and cross-linked and cured at 70°C to obtain the intrinsic flame-retardant solid-solid phase change material.

[0089] Comparative Example 1

[0090] 100g of polyethylene glycol 2000 was poured into a magnetic stirring oil bath at 70℃ and heated until completely melted. Boric acid (the molar ratio of boric acid to polyethylene glycol is 1:3) was added at 160℃ and 700rpm and stirred continuously for 6 hours. Phosphorus pentoxide (the molar ratio of phosphorus pentoxide to polyethylene glycol 2000 is 1:2) was added at 700rpm and 130℃ and stirred continuously for 2 hours to obtain borate phosphate ester, a phase change material with hydroxyl groups.

[0091] 78g of the borate phosphate ester of the phase change material containing hydroxyl groups was added to an oil bath at 80°C and melted. Then, 18g of diphenylmethane diisocyanate was added and stirred continuously until stirring was no longer possible. The mixture was then kept at the temperature and allowed to stand for 1 hour until the reaction was complete. The mixture was then poured into a mold and cross-linked and cured at 70°C to obtain the intrinsic flame-retardant solid-solid phase change material.

[0092] Comparative Example 2

[0093] 100g of polyethylene glycol 2000 was poured into a magnetic stirring oil bath at 70℃ and heated until completely melted. Boric acid (the molar ratio of boric acid to polyethylene glycol is 1:3) was added at 160℃ and 700rpm and stirred continuously for 6 hours. Phosphorus pentoxide (the molar ratio of phosphorus pentoxide to polyethylene glycol 2000 is 1:2) was added at 700rpm and 130℃ and stirred continuously for 2 hours to obtain borate phosphate ester, a phase change material with hydroxyl groups.

[0094] 78g of the borate phosphate ester of the phase change material containing hydroxyl groups was added to an oil bath at 80°C and melted. Then, 18g of melamine was added and stirred continuously until stirring was no longer possible. The mixture was then kept at the temperature and allowed to stand for 1 hour until the reaction was complete. The mixture was then poured into a mold and cross-linked and cured at 70°C to obtain the intrinsic flame-retardant solid-solid phase change material.

[0095] Test case

[0096] Leakage resistance test: The improvement in leakage resistance verifies the successful grafting of melamine and diphenylmethane diisocyanate onto polyethylene glycol borate phosphate. The specific test procedure involves placing the intrinsic flame-retardant solid-solid phase change materials described in Examples 1-3 on a constant-temperature heating platform at 150°C, observing and recording the appearance and mass changes before and after the leakage resistance test at regular intervals. The thermal stability and mass change of the intrinsic flame-retardant solid-solid phase change materials described in Examples 1-3 are characterized by the mass change curves during the leakage resistance test. Figure 1 The leakage resistance test results are those of the intrinsic flame-retardant solid-solid phase change material described in Example 1. Figure 2 The leakage resistance test results are for the intrinsic flame-retardant solid-solid phase change material described in Example 2. Figure 3 The images show the leakage resistance test results of the intrinsic solid-solid phase change material described in Example 3 (from left to right, the images show actual samples tested at 0h, 1h, 2h, 3h, 4h, and 5h). Figures 1-3 It can be seen that the intrinsic solid-solid phase change materials described in Examples 1-3 showed almost no leakage at high temperatures in the anti-leakage test, indicating that the intrinsic solid-solid phase change materials were successfully synthesized.

[0097] Flexibility test: The process of flexibility test is to manually bend and twist the sample strip and compare the performance of different sample strips; Figure 4 The flexible characterization structure of the intrinsic flame-retardant solid-solid phase change material described in Example 1 and Comparative Example 2 is composed of... Figure 4 It is known that the intrinsic flame-retardant solid-solid phase change material of the present invention has flexible properties and can achieve 180-degree bending and 90-degree twisting. The intrinsic flame-retardant solid-solid phase change material of Comparative Example 2 has bending ability, but does not have memory properties (cannot return to the initial state on its own).

[0098] Vertical burning test: The test procedure is in accordance with ISO 5660 standard; Figure 5 The image shows a vertical combustion test image of the intrinsic flame-retardant solid-solid phase change material described in Example 1. Figure 6 The images shown are vertical combustion test images of the intrinsic flame-retardant solid-solid phase change material described in Comparative Example 1. Figure 7 The image shows a vertical combustion test image of the intrinsic flame-retardant solid-solid phase change material described in Comparative Example 2; [Image showing the material's composition]. Figures 5-7 It is known that although diphenylmethane diisocyanate reacts with borate phosphate, a phase change material containing hydroxyl groups, to form a solid-solid phase change material, it exhibits dripping at high temperatures and fails to retard flame combustion. However, the reaction of melamine with borate phosphate, also a phase change material containing hydroxyl groups, also results in dripping at high temperatures, but flame combustion is suppressed. Furthermore, when diphenylmethane diisocyanate and melamine undergo simultaneous graft crosslinking, the sample does not drip at high temperatures after ignition, and flame combustion is prevented.

[0099] Thermal management effect: Figure 8 The thermal management effect of the intrinsic flame-retardant solid-solid phase change materials described in Example 1 and Comparative Examples 1-2 (the upper figure shows the temperature of the battery module under operating conditions, and the lower figure shows the temperature difference of the battery module under operating conditions) is determined by... Figure 8 It can be seen that, compared with Comparative Examples 1 and 2, Example 1 maintains the battery operating temperature below the safe operating temperature of 50°C, and the maximum temperature difference of its battery module is reduced by 2 to 3°C compared with Comparative Examples 1 and 2.

[0100] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An intrinsically flame-retardant solid-solid phase change material, characterized in that, The preparation raw material of the boron phosphate ester of the phase change material with hydroxyl group includes the phase change material with hydroxyl group, boric acid and diphosphorus pentoxide; The preparation raw material of the boron phosphate ester of the phase change material with hydroxyl group includes the phase change material with hydroxyl group, boric acid and diphosphorus pentoxide; The molar ratio of the phase change material with hydroxyl group, boric acid and diphosphorus pentoxide is 6: (1.8~2.2): (2.8~3.2); The mass ratio of the boron phosphate ester of the phase change material with hydroxyl group and the expanded graphite is (60~80):(1~3); The mass ratio of the boron phosphate ester of the phase change material with hydroxyl group and the melamine is (70~86):(5~16); The mass ratio of the boron phosphate ester of the phase change material with hydroxyl group and the isocyanate compound is (70~86):(8~20); The isocyanate compound is diphenylmethane diisocyanate; The preparation method of the intrinsic flame-retardant solid-solid phase change material includes the following steps: The molten phase change material with hydroxyl group and boric acid are first mixed to perform first esterification condensation reaction, and then mixed with diphosphorus pentoxide to perform second esterification condensation reaction, so as to obtain the boron phosphate ester of the phase change material with hydroxyl group; The molten boron phosphate ester of the phase change material with hydroxyl group is sequentially mixed with expanded graphite and melamine to perform grafting reaction, so as to obtain the second phase change material grafted with melamine; The second phase change material grafted with melamine and the isocyanate compound are mixed, and then solidified and formed, so as to obtain the intrinsic flame-retardant solid-solid phase change material.

2. The intrinsically flame retardant solid-solid phase change material of claim 1, wherein, The phase change material with hydroxyl group includes one or more of polyethylene glycol, cetyl alcohol, myristyl alcohol and stearyl alcohol; The polyethylene glycol includes one or more of polyethylene glycol 1500, polyethylene glycol 2000 and polyethylene glycol 4000.

3. The method of making an intrinsically flame-retardant solid-solid phase change material according to claim 1 or 2, characterized in that, The preparation method includes the following steps: The molten phase change material with hydroxyl group and boric acid are first mixed to perform first esterification condensation reaction, and then mixed with diphosphorus pentoxide to perform second esterification condensation reaction, so as to obtain the boron phosphate ester of the phase change material with hydroxyl group; The molten boron phosphate ester of the phase change material with hydroxyl group is sequentially mixed with expanded graphite and melamine to perform grafting reaction, so as to obtain the second phase change material grafted with melamine; The second phase change material grafted with melamine and the isocyanate compound are mixed, and then solidified and formed, so as to obtain the intrinsic flame-retardant solid-solid phase change material.

4. The production method according to claim 3, wherein The first esterification condensation reaction is performed under stirring; The temperature of the first esterification condensation reaction is 140~170℃, and the time is 5~8h.

5. The production method according to claim 3, wherein The second esterification condensation reaction is performed under stirring; The temperature of the second esterification condensation reaction is 90~130℃, and the time is 2~3h.

6. The production method according to claim 3, wherein After being mixed with the expanded graphite, first stirring is further included; The rotating speed of the first stirring is 400~800 rpm, and the time is 1~2h.

7. The production method according to claim 3, wherein After being mixed with the melamine, second stirring is further included; The rotating speed of the second stirring is 600~1000 rpm, and the time is 0.5~1h.

8. A battery module, characterized by The battery module and the phase change material framework are included; The material of the phase change material skeleton is the intrinsic flame-retardant solid-solid phase change material in claim 1 or 2 or the intrinsic flame-retardant solid-solid phase change material prepared by the preparation method in any one of claims 3-7.

9. Use of the battery module of claim 8 in energy storage devices and electric vehicles.

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