Multi-phase composite phase change material and preparation method and application thereof

Abstract

The invention belongs to the technical field of battery safety protection, and relates to a multiphase composite phase change material and a preparation method and application thereof, and the multiphase composite phase change material is composed of a composite matrix and a functional additive; wherein the composite matrix is composed of at least one inorganic hydrated salt and at least one organic matter; the multiphase composite phase change material has a phase change temperature point in at least one temperature interval of a low-temperature area, a medium-temperature area and a high-temperature area, and / or has at least one phase change temperature point in any one temperature interval of the low-temperature area, the medium-temperature area and the high-temperature area. The multi-phase composite phase change material provided by the invention breaks through the technical limitation of a single phase change interval, can realize a phase change function in multiple intervals of low temperature, medium temperature and high temperature, and has multiple effects of heat preservation, temperature equalization, heat insulation and heat dissipation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery safety protection, and relates to a phase change material, in particular to a multi-phase state composite phase change material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of new energy vehicles, energy storage systems and other fields, the working temperature stability and safety of lithium batteries as the core energy carrier have become the key bottleneck for technical breakthrough. The performance of lithium batteries is closely related to temperature: in a low temperature environment (-20℃ to 10℃), the increase of electrolyte viscosity and the decrease of ion migration rate will cause a sharp decrease of battery capacity, a significant reduction of charging and discharging efficiency, and even cause safety hazards such as lithium dendrite precipitation; in a medium temperature working condition (30℃ to 70℃), the battery can maintain basic performance, but a large local temperature difference will cause inconsistent aging speed of the cells in the module, and long-term use will exacerbate capacity attenuation and shorten the service life; when the battery is in thermal runaway (temperature ≥ 90℃), the internal chemical reaction heat release rate exceeds the heat dissipation capacity, and a chain reaction is easily triggered, causing the temperature to soar to above 150℃ in a short time, and even causing combustion and explosion.

[0003] To address the above problems, phase change materials have become one of the core solutions for lithium battery thermal management due to their characteristics of absorbing or releasing a large amount of latent heat during phase change. Currently, the mainstream phase change material thermal insulation products can be divided into three categories: (1) low-temperature phase change materials, mainly for battery insulation needs in cold regions, maintaining the battery temperature in a reasonable range (-10℃ to 10℃) through phase change latent heat, but unable to cope with medium and high temperature working conditions; (2) medium-temperature phase change materials, focusing on the temperature control of battery normal operation (such as fast charging, high-speed driving), avoiding the generation of hot spots by absorbing excess heat, but failing in low temperature or thermal runaway scenarios; (3) high-temperature phase change materials, mainly used for thermal runaway protection, delaying temperature rise by phase change heat absorption, and some materials form a thermal insulation layer to block heat diffusion after phase change, but only work in the ≥90℃ range, unable to consider low temperature insulation or medium temperature uniformity.

[0004] For example, aerogel thermal insulation sheets can play a certain role in thermal insulation during high-temperature thermal runaway, but they cannot insulate the battery at low temperatures, and cannot adjust the temperature difference between the cells at medium temperatures, making it difficult for the battery system to work stably in complex environments (such as cross-regional transportation, high-temperature areas with large day-night temperature differences). Even worse, when the heat generated by the battery thermal runaway continues to accumulate, exceeding the bearing threshold of the thermal insulation material, it will trigger a "heat eruption" phenomenon, causing high-temperature gas and flames to be released instantaneously, causing more serious safety accidents.

[0005] It is evident that current traditional phase change materials in the industry generally suffer from limited functionality and insufficient adaptability to various scenarios, failing to meet the thermal management requirements of batteries throughout their entire lifecycle and across all scenarios. Therefore, how to overcome the technical limitations of a single phase change range and develop a composite phase change material capable of achieving phase change functionality across multiple ranges (low, medium, and high temperatures) while simultaneously providing multiple benefits such as heat preservation, temperature equalization, thermal insulation, and heat dissipation has become a pressing issue for those skilled in the art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a multiphase composite phase change material, its preparation method, and its application, breaking through the technical limitations of a single phase change range. It can achieve phase change functions in multiple ranges, including low temperature, medium temperature, and high temperature, while also providing multiple benefits such as heat preservation, temperature uniformity, heat insulation, and heat dissipation.

[0007] To achieve this objective, the present invention employs the following technical solution:

[0008] In a first aspect, the present invention provides a multiphase composite phase change material, which is composed of a composite matrix and functional additives.

[0009] The composite matrix is ​​composed of at least one inorganic hydrated salt and at least one organic compound.

[0010] The multiphase composite phase change material has a phase change temperature point in at least one temperature range of low temperature, medium temperature and high temperature, and / or has at least one phase change temperature point in any temperature range of low temperature, medium temperature and high temperature.

[0011] The multiphase composite phase change material provided by this invention uses inorganic hydrated salts and organic matter as a composite matrix, supplemented by functional additives. By leveraging the synergistic effect between different raw materials, it overcomes the technical limitations of a single phase change range and the limitation of existing technologies that can only provide thermal insulation. It can achieve phase change function in multiple ranges, including low temperature, medium temperature, and high temperature. That is, it can keep the battery warm at low temperature, maintain the uniform temperature of the battery module at medium temperature, and expand to form a heat insulation layer after phase change at high temperature and conduct heat away, avoiding secondary risks caused by heat accumulation. It has multiple functions such as heat preservation, temperature uniformity, heat insulation, and heat dissipation, meeting the needs of batteries in complex operating conditions such as low temperature storage, medium temperature use, and high temperature thermal runaway protection.

[0012] Preferably, the temperature of the low-temperature zone is ≤10℃.

[0013] Preferably, the temperature in the medium temperature zone is 30-70°C.

[0014] Preferably, the temperature of the high-temperature zone is ≥90℃.

[0015] Preferably, the total mass of the composite matrix is ​​used as the calculation basis, and the content of the inorganic hydrated salt is 55%-85%.

[0016] Preferably, the total mass of the composite matrix is ​​used as the calculation basis, and the content of the organic matter is 15%-45%.

[0017] Preferably, the functional additive includes at least one or a combination of at least two of nucleating agents, wetting agents, or crosslinking agents.

[0018] Preferably, the total mass of the multiphase composite phase change material is used as the calculation basis, and the content of the functional additive is ≤3%.

[0019] Preferably, the phase transition temperature of the multiphase composite phase change material in the low-temperature region is between -10°C and 0°C, or between 0°C and 10°C.

[0020] Preferably, the phase transition temperature of the low-temperature zone is adjusted by the type and / or content of the inorganic hydrated salt, or by the chain length of the organic matter and / or the concentration of the functional additive.

[0021] Preferably, the phase transition temperature of the multiphase composite phase change material is between 30°C and 40°C in the medium temperature range, or between 40°C and 70°C.

[0022] Preferably, the phase transition temperature of the intermediate temperature zone is adjusted by the content and / or compounding of organic matter.

[0023] Preferably, the phase transition temperature of the multiphase composite phase change material in the high-temperature region is between 90°C and 150°C.

[0024] Preferably, the phase transition temperature of the high-temperature zone is adjusted by the content of inorganic hydrated salts and / or organic matter, or by the type of functional additives.

[0025] Preferably, the functional additive further includes carbon-based materials and / or metal-based materials.

[0026] Preferably, the functional additive further includes any one or a combination of at least two of the following: eutectic regulator, anti-overcooling regulator, phase separation regulator, or flexible self-healing material.

[0027] Preferably, the functional additive further includes an interface strengthener.

[0028] In a second aspect, the present invention provides a method for preparing a multiphase composite phase change material as described in the first aspect, comprising: mixing an inorganic hydrated salt and some functional additives, stirring evenly and then adding an organic substance, continuing to stir and then adding the remaining functional additives to obtain a multiphase composite phase change material.

[0029] Thirdly, the present invention provides an application of the multiphase composite phase change material as described in the first aspect, wherein the multiphase composite phase change material is used for at least one of thermal management in the low-temperature region, thermal management in the medium-temperature region, and thermal protection in the high-temperature region.

[0030] The thermal protection of the high-temperature zone includes the use of the same multiphase composite phase change material to achieve low-temperature thermal conductivity, medium-temperature thermal absorption, and high-temperature thermal insulation.

[0031] In this invention, the temperature of the low-temperature zone is ≤10℃, the temperature of the medium-temperature zone is 30-70℃, and the temperature of the high-temperature zone is ≥90℃.

[0032] In contrast, in the thermal protection of the high-temperature zone, the temperature of the low-temperature heat conduction is <90℃, the temperature of the medium-temperature heat absorption is 90-150℃, and the temperature of the high-temperature insulation is >150℃.

[0033] Fourthly, the present invention provides a phase change insulation component, including a phase change insulation sheet and an encapsulation layer disposed on both sides of the phase change insulation sheet.

[0034] The phase change insulation sheet is composed of a thermal insulation support material and a multiphase composite phase change material, and the multiphase composite phase change material is the multiphase composite phase change material described in the first aspect.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The multiphase composite phase change material provided by this invention uses inorganic hydrated salts and organic matter as a composite matrix, supplemented by functional additives. By leveraging the synergistic effect between different raw materials, it overcomes the technical limitations of a single phase change range and the limitation of existing technologies that can only provide thermal insulation. It can achieve phase change function in multiple ranges, including low temperature, medium temperature, and high temperature. That is, it can keep the battery warm at low temperature, maintain the uniform temperature of the battery module at medium temperature, and expand to form a heat insulation layer after phase change at high temperature and conduct heat away, avoiding secondary risks caused by heat accumulation. It has multiple functions such as heat preservation, temperature uniformity, heat insulation, and heat dissipation, meeting the needs of batteries in complex operating conditions such as low temperature storage, medium temperature use, and high temperature thermal runaway protection. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating the method for preparing phase change thermal insulation components using the multiphase composite phase change materials obtained in Examples 1-5, respectively.

[0038] Among them: 1-phase change material; 2-functional filler; 3-multiphase composite phase change material; 4-thermal insulation support material; 5-phase change thermal insulation sheet; 6-encapsulation layer.

[0039] Figure 2This is a structural diagram showing the arrangement of the phase change insulation components obtained in Examples 1-5 for thermal propagation suppression experiments.

[0040] Figure 3 The thermal spread suppression test curve of the phase change thermal insulation component obtained from Example 1 is shown.

[0041] Figure 4 The thermal spread suppression test curve of the phase change thermal insulation component obtained from Example 2 is shown.

[0042] Figure 5 The thermal spread suppression test curve of the phase change thermal insulation component obtained from Example 3 is shown.

[0043] Figure 6 The thermal spread suppression test curve of the phase change thermal insulation component obtained from Example 4 is shown.

[0044] Figure 7 The thermal spread suppression test curve of the phase change thermal insulation component obtained from Example 5 is shown. Detailed Implementation

[0045] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0046] One embodiment of the present invention provides a multiphase composite phase change material, which is composed of a composite matrix and functional additives.

[0047] The composite matrix is ​​composed of at least one inorganic hydrated salt and at least one organic compound.

[0048] The multiphase composite phase change material has a phase change temperature point in at least one temperature range of low temperature, medium temperature and high temperature, and / or has at least one phase change temperature point in any temperature range of low temperature, medium temperature and high temperature.

[0049] The multiphase composite phase change material provided by this invention uses inorganic hydrated salts and organic matter as a composite matrix, supplemented by functional additives. By leveraging the synergistic effect between different raw materials, it overcomes the technical limitations of a single phase change range and the limitation of existing technologies that can only provide thermal insulation. It can achieve phase change function in multiple ranges, including low temperature, medium temperature, and high temperature. That is, it can keep the battery warm at low temperature, maintain the uniform temperature of the battery module at medium temperature, and expand to form a heat insulation layer after phase change at high temperature and conduct heat away, avoiding secondary risks caused by heat accumulation. It has multiple functions such as heat preservation, temperature uniformity, heat insulation, and heat dissipation, meeting the needs of batteries in complex operating conditions such as low temperature storage, medium temperature use, and high temperature thermal runaway protection.

[0050] The inorganic hydrated salt, as one of the core functional components of the composite phase change material, plays a dominant role in phase change in the low-temperature region and is key to the thermal insulation function of the phase change material in low-temperature environments. Meanwhile, the inorganic hydrated salt generally has a high phase change enthalpy (typically 200-300 J / g), enabling it to absorb or release a large amount of heat during the phase change process, thereby effectively suppressing temperature fluctuations in the battery system.

[0051] Furthermore, the organic matter, as another core functional component of the composite phase change material, plays a dominant role in phase change primarily in the mid-temperature and high-temperature regions, and its specific adjustment can be achieved through chain length and molar ratio. Simultaneously, organic matter generally exhibits low corrosivity and good chemical stability, reducing the deliquescence of inorganic hydrated salts. Moreover, the molecular structure of organic matter can combine with the liquid in inorganic hydrated salts to form a three-dimensional network structure, promoting uniform distribution of the liquid phase and the inorganic salt solid phase, forming a good interfacial bond, reducing phase separation, and thus improving the homogeneity of the composite system.

[0052] It is evident that the synergistic combination of inorganic hydrated salts and organic matter in the composite matrix achieves complementary phase change temperature ranges. Specifically, inorganic hydrated salts cover the low temperature range, while organic matter covers the medium and high temperature ranges. Furthermore, the addition of functional additives allows for continuous phase change across multiple ranges, meeting the needs of batteries across all scenarios. Moreover, the high latent heat of inorganic hydrated salts combined with the high stability of organic matter ensures both heat regulation capability and reduces material degradation rate. Organic matter also acts as a dispersion medium for inorganic hydrated salts, preventing their crystallization and aggregation, while inorganic hydrated salts enhance the thermal conductivity of organic matter, ultimately forming an integrated function of "heat absorption, heat conduction, and heat insulation."

[0053] In some embodiments, the temperature of the low-temperature zone is ≤10℃, for example, it can be -10℃, -9℃, -8℃, -7℃, -6℃, -5℃, -4℃, -3℃, -2℃, -1℃, 0℃, 1℃, 2℃, 3℃, 4℃, 5℃, 6℃, 7℃, 8℃, 9℃ or 10℃, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0054] In some embodiments, the temperature of the intermediate temperature zone is 30-70°C, for example, it can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0055] In some embodiments, the temperature of the high-temperature zone is ≥90°C, for example, it can be 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C or 100°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0056] In some embodiments, the total mass of the composite matrix is ​​used as the calculation basis, and the content of the inorganic hydrated salt is 55%-85%, for example, it can be 55%, 60%, 65%, 70%, 75%, 80% or 85%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] In some embodiments, the total mass of the composite matrix is ​​used as the calculation basis, and the content of the organic matter is 15%-45%, for example, it can be 15%, 20%, 25%, 30%, 35%, 40% or 45%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0058] As previously mentioned, inorganic hydrated salts are the core carriers for low-temperature phase transitions, while organic matter dominates medium- and high-temperature phase transitions. This invention can specifically cover different temperature ranges by adjusting the content range of both. For example, when it is necessary to enhance low-temperature performance (such as battery insulation in cold regions), the content of inorganic hydrated salts can be appropriately increased to utilize their high latent heat characteristics to stabilize heat in the low-temperature range; when the focus is on medium- and high-temperature control (such as battery fast charging temperature equalization or thermal runaway protection), the content of organic matter can be appropriately increased to accurately cover the medium- and high-temperature zones.

[0059] Furthermore, while inorganic hydrated salts have high phase transition enthalpy but are prone to phase separation and deliquescence, and organic compounds are highly stable but have low latent heat, this invention achieves a complementary advantage through content adjustment. For example, in scenarios involving rapid heat absorption / release (such as heat buffering during low-temperature startup), the content of inorganic hydrated salts can be appropriately increased to enhance the overall heat storage capacity of the material; in scenarios involving long-term, high-frequency use (such as daily charging and discharging of power batteries), the content of organic compounds can be appropriately increased to enhance the material's resistance to phase separation and reduce performance degradation during cycling.

[0060] In some embodiments, the functional additive includes at least one or a combination of at least two of nucleating agents, wetting agents, or crosslinking agents. Typical but non-limiting combinations include combinations of nucleating agents and wetting agents, combinations of wetting agents and crosslinking agents, combinations of nucleating agents and crosslinking agents, or combinations of nucleating agents, wetting agents, and crosslinking agents.

[0061] For example, the nucleating agent can be selected from borax, silicon dioxide, aluminum oxide, chitin nanocrystals, graphene oxide, nano-copper, magnesium chloride hexahydrate, sodium dihydrogen phosphate dihydrate, sodium tartrate dihydrate, sodium thiosulfate pentahydrate, etc.; the wetting agent can be selected from fluorinated ether compounds, such as 1,1,1,3,3,3-hexafluoroisopropylmethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 2,2,2-trifluoroethylmethyl ether, 1,1,2,2-tetrafluoroethylethyl ether, etc.; the crosslinking agent can be selected from hexahydrophthalic anhydride, vinyltriethoxysilane, phosphoric acid, dicumyl peroxide, diethylenetriamine, boric acid, 2-isopropylimidazolium, propylene glycol, dopamine, and polyvinyl alcohol, etc. Any additive that can achieve the corresponding function is acceptable; the specific types of functional additives are not specifically limited here.

[0062] In some embodiments, the total mass of the multiphase composite phase change material is used as the calculation basis, and the content of the functional additive is ≤3%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5% or 3%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0063] In some embodiments, the phase transition temperature of the multiphase composite phase change material in the low-temperature region is between -10°C and 0°C, for example, it can be -10°C, -9°C, -8°C, -7°C, -6°C, -5°C, -4°C, -3°C, -2°C, -1°C or 0°C, or between 0°C and 10°C, for example, it can be 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C or 10°C, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0064] In some embodiments, the phase transition temperature of the low-temperature region is adjusted by the type and / or content of inorganic hydrated salts, or by the chain length of organic matter and / or the concentration of functional additives.

[0065] For example, adding 10wt% NaCl or 15wt% K2CO3 to a composite phase change material can achieve a phase change temperature between -10℃ and 0℃. By reducing the NaCl content to 4wt% and adding some Na2SO4, a phase change temperature between 0℃ and 10℃ can be achieved. Alternatively, replacing NaCl with 8-12wt% NH4Cl can also achieve a phase change temperature between 0℃ and 10℃. Adding 5-10wt% hexanol to fatty acids can achieve phase change temperatures between -10℃ and 0℃ and between 0℃ and 10℃. Paraffin can achieve the above effects by adjusting the chain length through compounding.

[0066] In some embodiments, the phase transition temperature of the multiphase composite phase change material in the mid-temperature region is between 30°C and 40°C, for example, it can be 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C or 40°C, or between 40°C and 70°C, for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0067] In some embodiments, the phase transition temperature of the intermediate temperature zone is adjusted by the content and / or compounding of organic matter.

[0068] For example, in composite phase change materials, the decanoic acid-lauric acid-palmitic acid or fatty acid-hexadecyl alcohol system can achieve a temperature range of 45℃-60℃ by adjusting the ratio; the binary compound of fatty acids / fatty alcohols can achieve a temperature range of 30℃-45℃.

[0069] In some embodiments, the phase transition temperature of the multiphase composite phase change material in the high-temperature region is between 90°C and 150°C, for example, it can be 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0070] In some embodiments, the phase transition temperature of the high-temperature zone is adjusted by the content of inorganic hydrated salts and / or organic matter, or by the type of functional additives.

[0071] For example, in composite phase change materials, high-melting-point salts are combined with stearic acid and other substances to form new eutectic points, thereby raising the phase change temperature to 90℃-150℃; some nitrates and long-chain fatty acids can also be adjusted in proportion to raise the phase change temperature to 100℃-120℃; the addition of metal oxides (such as titanium dioxide, silicon dioxide, etc.) can also raise the phase change temperature of high-melting-point organic materials to above 90℃.

[0072] In some embodiments, the functional additives further include carbon-based materials and / or metal-based materials.

[0073] In this invention, the addition of carbon-based materials and / or metal-based materials can improve the lifespan and reliability of composite phase change materials. For example, using carbon nanofibers or multi-walled carbon nanotubes in composite phase change materials at a content of 1wt%-10wt% can achieve 300-1000 cycles of phase change materials without degradation, and improve mechanical strength by 20%-100%.

[0074] In some embodiments, the functional additive further includes any one or a combination of at least two of a eutectic regulator, an anti-overcooling regulator, a phase separation regulator, or a flexible self-healing material. Typical but non-limiting combinations include a combination of a eutectic regulator and an anti-overcooling regulator, a combination of an anti-overcooling regulator and a phase separation regulator, or a combination of a phase separation regulator and a flexible self-healing material.

[0075] For example, the eutectic regulator can be a polyol, such as glycerol; the anti-overcooling regulator can be borax, silica, etc.; the phase separation regulator can be a surfactant, such as sodium dodecyl sulfate, Tween series, etc.; and the flexible self-healing material can be dicyclopentadiene. With the addition of these additives, a phase shift of less than 3°C can be achieved within a lifespan of 500-2000 cycles.

[0076] In some embodiments, the functional additive also includes an interface strengthener to further improve the lifespan and reliability of the composite phase change material.

[0077] In some embodiments, the lifespan and reliability of composite phase change materials can be further improved by modifying the carrier substrate and encapsulation materials, such as polymer three-dimensional skeletons and improving the tensile strength of encapsulation materials.

[0078] One embodiment of the present invention also provides a method for preparing the multiphase composite phase change material described in any of the above embodiments, comprising: mixing inorganic hydrated salts and some functional additives, stirring evenly and then adding organic matter, continuing to stir and then adding the remaining functional additives to obtain the multiphase composite phase change material.

[0079] One embodiment of the present invention also provides an application of the multiphase composite phase change material described in any of the above embodiments, wherein the multiphase composite phase change material is used for at least one of thermal management in the low-temperature region, thermal management in the medium-temperature region, and thermal protection in the high-temperature region.

[0080] The temperature of the low-temperature zone is ≤10℃, the temperature of the medium-temperature zone is 30-70℃, and the temperature of the high-temperature zone is ≥90℃.

[0081] For thermal protection in high-temperature regions, the multiphase composite phase change material provided by this invention not only has the ability to regulate temperature by its own phase change temperature point, but also has the functions of low-temperature thermal conduction (<90℃), medium-temperature thermal absorption (90-150℃, i.e., phase change temperature) and high-temperature thermal insulation (>150℃).

[0082] Specifically, the low-temperature thermal management (≤10℃) addresses issues such as increased electrolyte viscosity, decreased ion migration rate, and lithium dendrite precipitation in lithium batteries at low temperatures, maintaining battery capacity and safety performance. The mid-temperature thermal management (30-70℃) solves the problems of localized hot spots and excessive temperature differences between cell modules during normal operation, preventing overall capacity decay and shortened lifespan due to inconsistent cell aging rates. The high-temperature thermal protection (≥90℃) achieves full-chain thermal protection through phase transitions and structural changes of the same material at different temperature stages, rather than relying on traditional methods. The single function of high-temperature materials is only heat insulation: (1) In the low-temperature heat conduction stage (<90℃), before reaching the thermal runaway threshold, the heat conduction process can avoid local heat accumulation in the battery pack, laying the foundation for subsequent thermal protection; (2) In the medium-temperature heat absorption stage (90-150℃, i.e., phase change temperature), i.e. the initial stage of thermal runaway, the heat absorption process can delay the temperature rise, giving the battery management system time to trigger emergency measures such as cooling and power outage; (3) In the high-temperature heat insulation stage (>150℃), i.e. the thermal runaway outbreak period, the heat insulation material can block the transfer of heat to adjacent cells, avoiding heat spread and triggering a chain reaction.

[0083] As can be seen, the multiphase composite phase change material provided by this invention realizes the individual or combined application of thermal management in the low temperature region, thermal management in the medium temperature region, and thermal protection in the high temperature region. It breaks through the limitation of traditional phase change materials that can only achieve a single function in a single temperature range. Through the synergistic effect of different material components, it realizes the full-chain progressive thermal regulation of thermal protection in the high temperature region. Moreover, all application scenarios strictly match the phase change characteristics of the material and the temperature range definition.

[0084] One embodiment of the present invention also provides a phase change insulation component, including a phase change insulation sheet and an encapsulation layer disposed on both sides of the phase change insulation sheet.

[0085] The phase change insulation sheet is composed of a thermal insulation support material and a multiphase composite phase change material, and the multiphase composite phase change material is the multiphase composite phase change material described in any of the above embodiments.

[0086] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0087] Examples 1-5

[0088] This set of embodiments provides a multiphase composite phase change material and its preparation method. The composition of the multiphase composite phase change material provided in each embodiment is shown in Table 1 below, according to the weight parts.

[0089] Table 1

[0090]

[0091] The preparation method of the multiphase composite phase change material provided in each embodiment includes: first, mixing and stirring the inorganic hydrated salt and functional additives according to the types of substances and corresponding weight parts in Table 1 above, then adding organic matter in sequence according to the proportion, continuing to stir, then adding functional filler (5 parts silicon carbide, 2 parts expanded graphite, 1.5 parts alumina) and performance enhancement material (1 part carbon nanotube, 5 parts glass fiber), continuing to stir evenly to obtain the multiphase composite phase change material.

[0092] Application Examples 1-5

[0093] This group of application examples respectively uses the multiphase composite phase change materials described in Examples 1-5 to prepare phase change thermal insulation components, such as... Figure 1 As shown, the phase change insulation component includes a phase change insulation sheet 5 and an encapsulation layer 6 disposed on both sides of the phase change insulation sheet 5. The phase change insulation sheet 5 is composed of a heat insulation support material 4 and a multiphase composite phase change material 3. The multiphase composite phase change material 3 is composed of a phase change material 1 and a functional filler 2.

[0094] The encapsulation layer 6 is made of aluminum-plastic film; the heat insulation support material 4 is made of fiberglass mat.

[0095] Performance testing:

[0096] Adopting such Figure 2 The arrangement shown was used to conduct thermal propagation suppression experiments on phase change insulation components.

[0097] The specific test conditions are as follows: Prepare two 161Ah battery cells (cell ① and cell ②). Under constant current and constant voltage conditions, charge the cells to 100% SOC and let them stand for 6 hours. Then, prepare two tooling fixtures and place the two battery cells between the fixtures. Place a multiphase composite phase change material between the battery cells. A heating element is placed in close contact with cell ① to trigger thermal runaway. The power of the heating element is set to 600W. Three thermocouples are placed on the large surface and top of each of the two battery cells. After the arrangement is completed, the fixtures are locked with bolts, and the locking pressure is 1500~3000N.

[0098] The thermal spread suppression test curves of the phase change thermal insulation components obtained in Application Examples 1 to 5 are respectively shown in the figure. Figures 3 to 7 .

[0099] Analysis of the test curves shows that the front temperature of the trigger cell generally exceeds 750℃, and some even reach 900℃. However, after the multiphase composite phase change material absorbs heat, the back temperature of the trigger cell is significantly reduced, and the temperature reduction can reach more than 100℃. Therefore, the characteristic of the multiphase composite phase change material to significantly reduce the highest temperature of the runaway cell when thermal runaway occurs can effectively reduce the harm caused by high temperature.

[0100] Furthermore, the multiphase composite phase change material exhibited three temperature states in the thermal propagation test: a rapid temperature rise in the first stage; a constant temperature in the second stage; and a continued temperature rise to its maximum point followed by cooling in the third stage. The rapid temperature rise in the first stage demonstrates the material's good thermal conductivity in the low-temperature range. This characteristic can greatly assist the battery thermal management system in the battery pack, helping to achieve more uniform cell temperatures and extending battery life. The constant temperature in the second stage is an advantage brought about by the phase change material's ability to absorb heat and maintain a constant temperature. After thermal runaway occurs in the battery, the multiphase composite phase change material can significantly absorb the heat from the runaway cell, buying time for liquid cooling to start and protecting the safety of adjacent cells. The third stage is the thermal insulation stage; after completing the phase change, the multiphase composite phase change material becomes a thermally insulating porous material, continuing to block heat transfer to adjacent cells.

[0101] In summary, multiphase composite phase change materials can indeed absorb and block the heat of thermal runaway battery cells to a certain extent, preventing the occurrence of heat propagation.

[0102] Therefore, the multiphase composite phase change material provided by this invention uses inorganic hydrated salts and organic matter as a composite matrix, supplemented by functional additives. By leveraging the synergistic effect between different raw materials, it breaks through the technical limitations of a single phase change range and the limitation of existing technologies that can only provide thermal insulation. It can achieve phase change function in multiple ranges, including low temperature, medium temperature, and high temperature. That is, it can keep the battery warm at low temperature, maintain the uniform temperature of the battery module at medium temperature, and expand to form a heat insulation layer after phase change at high temperature and conduct heat away, avoiding secondary risks caused by heat accumulation. It has multiple functions of heat preservation, temperature uniformity, heat insulation, and heat dissipation, meeting the needs of batteries in complex operating conditions such as low temperature storage, medium temperature use, and high temperature thermal runaway protection.

[0103] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A multi-phase composite phase change material, characterized in that, The multi-phase composite phase change material is composed of a composite matrix and a functional additive; The composite matrix is composed of at least one inorganic hydrated salt and at least one organic matter; The multi-phase composite phase change material has a phase change temperature point in at least one of the low temperature zone, the medium temperature zone and the high temperature zone, and / or has at least one phase change temperature point in any of the low temperature zone, the medium temperature zone and the high temperature zone.

2. The multi-phase composite phase change material of claim 1, wherein, The temperature of the low temperature zone is ≤10℃; And / or, the temperature of the medium temperature zone is 30-70℃; And / or, the temperature of the high temperature zone is ≥90℃.

3. The multi-phase composite phase change material of claim 1, wherein, The content of the inorganic hydrated salt is 55%-85%, based on the total mass of the composite matrix; And / or, the content of the organic matter is 15%-45%, based on the total mass of the composite matrix.

4. The multi-phase composite phase change material of claim 1, wherein, The functional additive at least includes any one or a combination of at least two of a nucleating agent, a wetting agent or a crosslinking agent; And / or, the content of the functional additive is ≤3%, based on the total mass of the multi-phase composite phase change material.

5. The multi-phase composite phase change material of any of claims 1-4, wherein, The phase change temperature point of the multi-phase composite phase change material in the low temperature zone is between -10℃ and 0℃, or between 0℃ and 10℃; The phase change temperature point of the low temperature zone is adjusted by the type and / or content of the inorganic hydrated salt, or by the chain length of the organic matter and / or the concentration of the functional additive.

6. The multi-phase composite phase change material of any of claims 1-4, wherein, The phase change temperature point of the multi-phase composite phase change material in the medium temperature zone is between 30℃ and 40℃, or between 40℃ and 70℃; The phase change temperature point of the medium temperature zone is adjusted by the content and / or compounding of the organic matter.

7. The multi-phase composite phase change material of any of claims 1-4, wherein, The phase change temperature point of the multi-phase composite phase change material in the high temperature zone is between 90℃ and 150℃; The phase change temperature point of the high temperature zone is adjusted by the content of the inorganic hydrated salt and / or the organic matter, or by the type of the functional additive.

8. The multi-phase composite phase change material of claim 4, wherein, The functional additive further includes a carbon-based material and / or a metal-based material; And / or, the functional additive further includes any one or a combination of at least two of a eutectic adjusting agent, an anti-supercooling adjusting agent, a phase separation adjusting agent or a flexible self-repairing material; And / or, the functional additive further includes an interface reinforcing agent.

9. A method of producing a multi-phase composite phase change material as claimed in any one of claims 1 to 8, characterised in that, The preparation method comprises: mixing the inorganic hydrated salt and part of the functional additive, stirring uniformly, adding the organic matter, continuing to stir, adding the remaining functional additive, and obtaining the multi-phase composite phase change material.

10. Use of a multi-phase composite phase change material according to any one of claims 1 to 8, characterized in that, The multi-phase composite phase change material is used for at least one of thermal management in the low temperature zone, thermal management in the medium temperature zone and thermal protection in the high temperature zone; The thermal protection in the high temperature zone includes simultaneously considering low temperature heat conduction, medium temperature heat absorption and high temperature heat insulation by using the same multi-phase composite phase change material.

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