Multi-component composite flexible phase change material, preparation method thereof and battery module
By preparing a multi-component composite flexible phase change material, and utilizing the supporting framework formed by olefin block copolymers and polyolefin thermoplastic elastomers, along with the thermally conductive fillers of hexagonal boron nitride and expanded graphite, the problems of low rigidity and low thermal conductivity of flexible phase change materials at room temperature were solved, thereby improving the heat dissipation performance and structural stability of the battery module.
Patent Information
- Application Number
- CN202511531252.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-24
- Publication Date
- 2026-01-09
AI Technical Summary
Existing flexible phase change materials still exhibit rigidity at room temperature and have low thermal conductivity, making it difficult to meet the heat dissipation requirements of battery modules. Especially in electric vehicles, traditional rigid phase change materials cannot make close contact with the battery surface, resulting in low heat transfer efficiency.
A multi-component composite structure consisting of a supporting framework, a phase change material, and a thermally conductive filler is adopted. The supporting framework is a three-dimensional porous network formed by olefin block copolymers and polyolefin thermoplastic elastomers. The phase change material is paraffin wax, and the thermally conductive filler is hexagonal boron nitride and expanded graphite. The multi-component composite flexible phase change material is prepared by melt blending and hot pressing.
A multi-component flexible phase change material with good flexibility and high thermal conductivity at room temperature has been developed, which can effectively prevent paraffin leakage, improve heat transfer efficiency, enhance the heat dissipation performance and structural stability of battery modules, and extend the service life of battery thermal management systems.
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Figure CN121293947A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of phase change material technology, and in particular, this application relates to a multi-component composite flexible phase change material and its preparation method, as well as a battery module. Background Technology
[0002] The current global energy structure is highly dependent on traditional fossil fuels such as oil, natural gas, and coal. The incomplete combustion of these fuels leads to low energy efficiency. Furthermore, their limited non-renewable reserves and the harmful substances produced during combustion cause environmental pollution and other problems, posing a serious challenge to sustainable development. Faced with these difficulties, the world is accelerating its transition to a clean and renewable energy era. Electric vehicles, as a significant achievement in the energy transition within the transportation sector, are continuously developing.
[0003] Lithium-ion batteries are widely used in the electric vehicle industry due to their various performance characteristics. However, with the continuous increase in energy density, the heat generated during charging and discharging also increases. Battery heat dissipation is crucial during the operation of electric vehicles. Without an effective heat dissipation mechanism, batteries may suffer from shortened lifespan and pose a serious threat to safety. Therefore, developing an effective battery management system to control the battery's operating temperature within the range of 25–50°C is critical.
[0004] For battery management systems relying on phase change materials (PCMs), traditional rigid PCMs struggle to achieve optimal fit with the battery surface, leading to inefficient heat transfer. In contrast, flexible PCMs can conform to the specific contours of the battery surface, promoting closer contact and minimizing air gaps, thereby accelerating heat transfer. Currently, to address the technical challenges of poor mechanical properties and lack of flexibility in PCMs, flexible meshes are constructed using cross-linked structures of flexible elastomers to achieve flexibility. However, most flexible PCMs only exhibit flexibility at temperatures close to or above the phase change temperature, remaining rigid at room temperature. This remains a critical issue to be addressed in the field of phase change thermal control.
[0005] Nevertheless, the low thermal conductivity of paraffin-based composite phase change materials has always limited the heat transfer rate and potential applications, especially for battery modules. Composite phase change materials need to be flexible enough while also improving thermal conductivity and heat dissipation capabilities to meet safety issues such as heat dissipation during battery module installation and cyclic charging. Summary of the Invention
[0006] Examples of this application provide a multi-component composite flexible phase change material and its preparation method, as well as a battery module, which has self-encapsulation properties, high thermal conductivity, and good flexibility and bending properties at room temperature.
[0007] The solution presented in this application is implemented through the following steps.
[0008] In a first aspect, this application discloses a multi-component composite flexible phase change material, comprising: The structure consists of a support framework, a phase change material, and a thermally conductive filler. The support framework forms a three-dimensional porous network structure, and the phase change material and thermally conductive filler are loaded into the pores of the support framework through impregnation or adsorption.
[0009] The supporting skeleton includes olefin block copolymers, polyolefin thermoplastic elastomers, and cross-linked polymers formed by olefin block copolymers and polyolefin thermoplastic elastomers. The phase change material includes paraffin wax, and the thermally conductive filler includes hexagonal boron nitride and expanded graphite.
[0010] Optionally, the mass ratio of the support frame, phase change material, and thermally conductive filler is 3~5:13~16:1~2.
[0011] Optionally, the mass percentage of hexagonal boron nitride in the thermally conductive filler is 30% to 70%, and / or; The mass percentage of expanded graphite in the thermally conductive filler is 30% to 70%.
[0012] Optionally, the phase transition temperature of the multi-component composite flexible phase change material is 45.8~46.42℃, and / or; The latent heat of phase change of the multi-component composite flexible phase change material is 152.93~158.33 J / g, and / or; The thermal conductivity of the multi-component composite flexible phase change material is 1.314~1.481 W / (m·K), and / or; The paraffin quality retention rate of the multi-component composite flexible phase change material is 99.55%~99.64%, and / or; The elongation at break of the multi-component composite flexible phase change material is 98.24%~102.65%.
[0013] In a second aspect, this application also discloses a method for preparing a multi-component composite flexible phase change material as described above, which includes mixing a supporting skeleton, a phase change material and a thermally conductive filler by melt blending to obtain a PA / POE / OBC / h-BN / EG raw material, and hot pressing the PA / POE / OBC / h-BN / EG raw material into shape.
[0014] Optionally, the melt blending method includes: S1. Polyolefin thermoplastic elastomer and molten paraffin are melt-blended to obtain PA / POE mixture; S2. The obtained PA / POE mixture and olefin block copolymer are melt-blended to obtain PA / POE / OBC mixture; S3. The obtained PA / POE / OBC mixture is melt-blended with hexagonal boron nitride to obtain a PA / POE / OBC / h-BN mixture; S4. The obtained PA / POE / OBC mixture is melt-blended with expanded graphite to obtain PA / POE / OBC / h-BN / EG raw material.
[0015] Optionally, the melt blending temperature in step S1 is 120~130℃, the initial stirring rate is 200~250rpm, the stirring rate increase rate is 50rpm / 10min, the final stirring rate is 400~500rpm, the stirring time is 1.0~1.5h, and / or; In step S2, the melt blending temperature is 160~170℃, the stirring rate is 300~400rpm, the stirring time is 30~40min, and / or; In step S3, the melt blending temperature is 160~170℃, the stirring rate is 250~300rpm, the stirring time is 30~40min, and / or; In step S4, the melt blending temperature is 160~170℃, the stirring rate is 150~200rpm, the stirring time is 30~40min, and / or; Hot pressing involves preheating the PA / POE / OBC / h-BN / EG raw materials to 80°C, then naturally cooling them to below 60°C before hot pressing. The hot pressing time is 30-40 minutes.
[0016] Optionally, the mass ratio of paraffin wax to polyolefin thermoplastic elastomer is 6:1 to 12:1, and / or; The mass ratio of PA / POE mixture to olefin block copolymer is 18:1 to 18:2, and / or; The mass of hexagonal boron nitride is 2-3% of the mass of the PA / POE / OBC / h-BN mixture, and / or; The mass of expanded graphite is 2-3% of the mass of the PA / POE / OBC / h-BN / EG mixture.
[0017] Alternatively, expanded graphite is prepared by the following method: Expandable graphite powder was placed in an alumina crucible and heat-treated using a microwave method. Optionally, the heating power for heat treatment is 600W~1000W, and the heating time is 30s~60s.
[0018] In a third aspect, this application also discloses a battery module, which includes a housing, a battery rack, and multiple power batteries. The battery rack is sleeved on the outside of the power batteries. The battery rack is made of the aforementioned multi-component composite flexible phase change material or a multi-component composite flexible phase change material made from the aforementioned multi-component composite flexible phase change material. The multiple power batteries are disposed in the housing.
[0019] This application has at least the following beneficial effects: The multi-component flexible phase change material of this application uses olefin block copolymers, polyolefin thermoplastic elastomers, and cross-linked polymers of olefin block copolymers and polyolefin thermoplastic elastomers as a supporting framework. The cross-linked polymers form a flexible network structure, which enhances the encapsulation performance of paraffin and the mechanical properties of the multi-component flexible phase change material. This prevents liquid paraffin leakage and imparts flexibility to the multi-component flexible phase change material, allowing it to be bent into various shapes according to application requirements, tightly bonded to other materials, improving heat transfer efficiency, and reducing interfacial thermal resistance. The multi-component flexible phase change material of this application also uses hexagonal boron nitride and expanded graphite as thermally conductive fillers. This not only constructs a continuous thermally conductive network, giving the multi-component flexible phase change material a high thermal response rate, but also enhances its encapsulation performance and high compressive strength. The multi-component flexible phase change material of this application has self-encapsulation properties, as well as high thermal conductivity and good flexibility and bending performance at room temperature, making it suitable for battery temperature control management.
[0020] The preparation method of the multi-component composite flexible phase change material of this application is simple, has a short molding time, can be rapidly formed, and has excellent thermal stability and cycle stability.
[0021] This application utilizes a multi-component composite flexible phase change material to encapsulate the power battery. Due to the significant difference in phase change temperatures between polyolefin thermoplastic elastomers and olefin block copolymers and paraffin wax, the paraffin wax retains its dense structure even as it melts. Uniform encapsulation of the paraffin wax with polyolefin thermoplastic elastomers and olefin block copolymers effectively prevents paraffin wax leakage. Simultaneously, the excellent mechanical properties of polyolefin thermoplastic elastomers and olefin block copolymers ensure that their physicochemical characteristics remain unchanged under normal operating temperatures of the power battery, providing the phase change material with good tensile strength and elasticity. This effectively buffers the impact of external forces, providing shock protection for the power battery and thus improving the service life of the battery thermal management system. Furthermore, transferring the heat from the power battery to the multi-component composite flexible phase change material improves heat dissipation performance. Additionally, the use of hexagonal boron nitride and expanded graphite for heat dissipation in the composite phase change layer enhances both overall structural stability and system heat dissipation efficiency. The battery module of this application utilizes the constant flexibility, high enthalpy, and strong thermal conductivity of multi-component flexible phase change materials to achieve good cooperation with controlled components and improve the thermal control performance of the battery. Attached Figure Description
[0022] Figure 1 A flowchart illustrating the preparation process of the multi-component composite flexible phase change material in this application is disclosed.
[0023] Figure 2 A schematic diagram of the battery module in the example of this application is disclosed.
[0024] Figure 3 The melting process curves of DSC tests for Examples 1, 2 and 3 of this application are disclosed.
[0025] Figure 4 A comparison diagram of the thermal conductivity of Examples 1-3 and Comparative Example 3 of this application is disclosed.
[0026] Figure 5 Leakage prevention test diagrams for Embodiments 1, 2, and 3 of this application are disclosed.
[0027] Figure 6 Data analysis charts of paraffin quality retention rates for Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 of this application are disclosed.
[0028] Figure 7 A comparison diagram of the tensile strength of Example 3 and Comparative Example 2 of this application is disclosed.
[0029] Figure 8 A flowchart of the flexibility test of the multi-component composite flexible phase change material of Embodiment 1 of this application is disclosed.
[0030] The attached diagram lists the components represented by each number as follows: 1-Power battery; 2-Battery rack; 3-Box. Detailed Implementation
[0031] This invention discloses a multi-component composite flexible phase change material, its preparation method, and a battery module. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can obviously make modifications or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.
[0032] This application provides a multi-component composite flexible phase change material, comprising: The structure consists of a support framework, a phase change material, and a thermally conductive filler. The support framework forms a three-dimensional porous network structure, and the phase change material and thermally conductive filler are loaded into the pores of the support framework through impregnation or adsorption.
[0033] The supporting skeleton includes olefin block copolymers, polyolefin thermoplastic elastomers, and cross-linked polymers formed by olefin block copolymers and polyolefin thermoplastic elastomers. The phase change material includes paraffin wax, and the thermally conductive filler includes hexagonal boron nitride and expanded graphite.
[0034] Paraffin (PA), as a phase change material, has advantages such as low price, high heat storage density, and good stability, and is widely used in medium and low temperature phase change heat storage and temperature control.
[0035] Olefin block copolymers (OBCs) serve as a supporting framework, preventing liquid paraffin leakage and imparting flexibility to the multi-component composite flexible phase change material. Polyolefin thermoplastic elastomers (POEs) possess excellent room-temperature toughness. Combining olefin block copolymers and polyolefin thermoplastic elastomers can produce flexible phase change materials with even better performance. The multi-component composite flexible phase change material of this application achieves this by cross-linking olefin block copolymers and polyolefin thermoplastic elastomers, increasing the degree of cross-linking and forming a continuous flexible network structure. This improves the encapsulation performance and flexibility of the multi-component composite flexible phase change material, while reducing interfacial thermal resistance during use.
[0036] Hexagonal boron nitride (h-BN) is a highly thermally conductive additive with excellent thermal conductivity; expanded graphite (EG), as a carbon-based porous material, has advantages such as high thermal conductivity and abundant pore structure. The multi-component composite flexible phase change material of this application uses hexagonal boron nitride and expanded graphite as thermally conductive fillers to construct synergistic thermal conduction channels. This not only improves the thermal conductivity of the phase change material but also provides excellent encapsulation, preventing leakage of the liquid phase change material.
[0037] Optionally, the mass ratio of the support frame, phase change material, and thermally conductive filler is 3~5:13~16:1~2.
[0038] As an example, the mass ratio of the support frame, phase change material, and thermally conductive filler can be 3:16:1, 4:15:1, 5:14:1, 3:15:2, 4:14:2, or 5:13:2.
[0039] Optionally, the mass percentage of hexagonal boron nitride in the thermally conductive filler is 30% to 70%, and / or the mass percentage of expanded graphite in the thermally conductive filler is 30% to 70%.
[0040] As an example, the mass percentage of hexagonal boron nitride in the thermally conductive filler can be 30%, 40%, 50%, 60% or 70%, and the mass percentage of expanded graphite in the thermally conductive filler can be 70%, 60%, 50%, 40% or 30%.
[0041] Optionally, the phase transition temperature of the multi-component flexible phase change material is 45.8~46.42℃.
[0042] Optionally, the latent heat of phase change of the multi-component flexible phase change material is 152.93~158.33 J / g.
[0043] Optionally, the thermal conductivity of the multi-component composite flexible phase change material is 1.314~1.481 W / (m·K).
[0044] Optionally, the paraffin quality retention rate of the multi-component composite flexible phase change material is 99.55%~99.64%.
[0045] Optionally, the elongation at break of the multi-component composite flexible phase change material is 98.24%~102.65%.
[0046] The multi-component flexible phase change material of this application uses olefin block copolymers, polyolefin thermoplastic elastomers, and cross-linked polymers of olefin block copolymers and polyolefin thermoplastic elastomers as a supporting framework. The cross-linked polymers form a flexible network structure, which enhances the encapsulation performance of paraffin and the mechanical properties of the multi-component flexible phase change material. This prevents liquid paraffin leakage and imparts flexibility to the multi-component flexible phase change material, allowing it to be bent into various shapes according to application requirements, tightly bonded to other materials, improving heat transfer efficiency, and reducing interfacial thermal resistance. The multi-component flexible phase change material of this application also uses hexagonal boron nitride and expanded graphite as thermally conductive fillers. This not only constructs a continuous thermally conductive network, giving the multi-component flexible phase change material a high thermal response rate, but also enhances its encapsulation performance and high compressive strength. The multi-component flexible phase change material of this application has self-encapsulation properties, as well as high thermal conductivity and good flexibility and bending performance at room temperature, making it suitable for battery temperature control management.
[0047] Please see Figure 1 This application also provides a method for preparing a multi-component composite flexible phase change material as described above, which includes the following steps: S1. Preparation of expanded graphite A certain amount of expandable graphite powder is placed in an alumina crucible and heat-treated using a microwave method to obtain expanded graphite.
[0048] Optionally, the heating power for heat treatment is 600W~1000W, and the heating time is 30s~60s.
[0049] As an example, the heating power for heat treatment can be 600W, 700W, 800W, 900W or 1000W, and the heating time can be 30s, 45s or 60s.
[0050] S2, Preparation of PA / POE mixture A certain mass of paraffin wax is placed in a beaker, heated until it is completely melted, and then polyolefin thermoplastic elastomer is added. The mixture is stirred continuously until it is completely melted and blended to obtain a PA / POE mixture.
[0051] Optionally, the mass ratio of paraffin wax to polyolefin thermoplastic elastomer is 6:1 to 12:1.
[0052] As an example, the mass ratio of paraffin wax to polyolefin thermoplastic elastomer can be 6:1, 8:1, 10:1, or 12:1.
[0053] Optionally, the melt blending temperature in step S2 is 120~130℃, the initial stirring rate is 200~250rpm, the stirring rate increase rate is 50rpm / 10min, the final stirring rate is 400~500rpm, and the stirring time is 1.0~1.5h.
[0054] As an example, the melt blending temperature in step S2 can be 120°C, 122°C, 125°C, 128°C, or 130°C; the initial stirring rate can be 200 rpm, 210 rpm, 220 rpm, 230 rpm, 240 rpm, or 250 rpm; the final stirring rate can be 400 rpm, 420 rpm, 450 rpm, 480 rpm, or 500 rpm; and the stirring time can be 1.0 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, or 1.5 h.
[0055] S3. Preparation of PA / POE / OBC mixture An olefin block copolymer is added to the PA / POE mixture, and the mixture is continuously stirred until it is completely melted and blended to obtain a PA / POE / OBC mixture.
[0056] Optionally, the mass ratio of the PA / POE mixture to the olefin block copolymer is 18:1 to 18:2.
[0057] As an example, the mass ratio of the PA / POE mixture to the olefin block copolymer can be 18:1, 18:1.5, or 18:2.
[0058] Optionally, the melt blending temperature in step S3 is 160~170℃, the stirring rate is 300~400rpm, and the stirring time is 30~40min.
[0059] As an example, the melt blending temperature in step S3 can be 160°C, 162°C, 165°C, 168°C or 170°C, the stirring rate can be 300 rpm, 320 rpm, 350 rpm, 380 rpm or 400 rpm, and the stirring time can be 30 min, 32 min, 35 min, 38 min or 40 min.
[0060] S4. Preparation of PA / POE / OBC / h-BN mixture Add hexagonal boron nitride to the PA / POE / OBC mixture and stir continuously until it is completely homogeneous to obtain the PA / POE / OBC / h-BN mixture.
[0061] Optionally, the mass of hexagonal boron nitride is 2 to 3% of the mass of the PA / POE / OBC / h-BN mixture.
[0062] As an example, the mass of hexagonal boron nitride can be 2%, 2.5%, or 3% of the mass of the PA / POE / OBC / h-BN mixture.
[0063] Optionally, the melt blending temperature in step S4 is 160~170℃, the stirring rate is 250~300rpm, and the stirring time is 30~40min.
[0064] As an example, the melt blending temperature in step S4 can be 160°C, 162°C, 165°C, 168°C or 170°C, the stirring rate can be 250 rpm, 280 rpm or 300 rpm, and the stirring time can be 30 min, 35 min or 40 min.
[0065] S5. Preparation of PA / POE / OBC / h-BN / EG raw materials Expanded graphite is added to the PA / POE / OBC / h-BN mixture, and the mixture is stirred continuously until it is completely homogeneous to obtain the PA / POE / OBC / h-BN / EG raw material.
[0066] Optionally, the mass of expanded graphite is 2 to 3% of the mass of the PA / POE / OBC / h-BN / EG mixture.
[0067] As an example, the mass of expanded graphite can be 2%, 2.5%, or 3% of the mass of the PA / POE / OBC / h-BN / EG mixture.
[0068] Optionally, the melt blending temperature in step S5 is 160~170℃, the stirring rate is 150~200rpm, and the stirring time is 30~40min.
[0069] As an example, the melt blending temperature in step S5 can be 160°C, 162°C, 165°C, 168°C or 170°C, the stirring rate can be 150 rpm, 180 rpm or 200 rpm, and the stirring time can be 30 min, 35 min or 40 min.
[0070] S6. Preparation of multi-component composite flexible phase change materials PA / POE / OBC / h-BN / EG raw materials are placed into a mold and hot-pressed to obtain PA / POE / OBC / h-BN / EG blocks, thus producing multi-component composite flexible phase change materials.
[0071] Optionally, hot pressing involves preheating the PA / POE / OBC / h-BN / EG raw materials to 80°C, then naturally cooling them to below 60°C before hot pressing, with a hot pressing time of 30~40 minutes.
[0072] The preparation method of the multi-component composite flexible phase change material of this application is simple, has a short molding time, can be rapidly formed, and has excellent thermal stability and cycle stability.
[0073] Please see Figure 2 This application also provides a battery module, which includes a housing 3, a battery rack 2 and a plurality of power batteries 1. The battery rack 2 is sleeved on the outside of the power batteries 1. The battery rack 2 is made of the aforementioned multi-component composite flexible phase change material or a multi-component composite flexible phase change material made of the aforementioned multi-component composite flexible phase change material. The plurality of power batteries 1 are disposed in the housing 3.
[0074] Optionally, the housing 3 is equipped with a power battery module 1, which has multiple power batteries 1 arranged in an array.
[0075] Optionally, the battery rack 2 has a loading hole adapted to the power battery 1, and the power battery 1 is placed in the loading hole so that the sidewall of the power battery 1 is covered with a multi-component flexible phase change material.
[0076] Optionally, the loading hole is a through hole, and the axial length of the loading hole is equal to the length of the power battery 1.
[0077] Optionally, the outer structure of the battery rack 2 is adapted to the inner structure of the housing 3.
[0078] This application utilizes a multi-component composite flexible phase change material to encapsulate the power battery 1. Due to the significant difference in phase change temperatures between the polyolefin thermoplastic elastomer and olefin block copolymer and paraffin wax, the paraffin wax maintains its dense structure even when melting. By uniformly encapsulating the paraffin wax with the polyolefin thermoplastic elastomer and olefin block copolymer, paraffin wax leakage is effectively prevented. Simultaneously, the polyolefin thermoplastic elastomer and olefin block copolymer possess excellent mechanical properties, ensuring that their physicochemical characteristics remain unchanged under normal operating temperatures of the power battery 1. This provides the phase change material with good tensile strength and elasticity, effectively buffering the impact of external forces and providing shock protection for the power battery 1, thereby improving the service life of the battery thermal management system. Furthermore, after the power battery 1 transfers heat to the multi-component composite flexible phase change material, heat dissipation performance is improved. Additionally, the use of hexagonal boron nitride and expanded graphite for heat dissipation in the composite phase change layer enhances both overall structural stability and system heat dissipation efficiency. The battery module of this application utilizes the constant flexibility, high enthalpy, and strong thermal conductivity of multi-component flexible phase change materials to achieve good cooperation with controlled components and improve the thermal control performance of the battery.
[0079] The present invention will be further described below with reference to the embodiments: Example 1 This application provides a multi-component composite flexible phase change material and its preparation method, which includes the following steps: First, a certain amount of expandable graphite powder was microwave-expanded at 800W for 30 seconds to obtain EG. Then, 34g of PA was heated in a beaker at 80°C until completely melted, and 3g of POE was added. The mixture was then heated and stirred continuously at 125°C at a rate of 300 rpm for 1 hour to ensure complete melting and blending, resulting in a PA / POE mixture. Next, 1g of OBC was added to the PA / POE mixture. The mixture was stirred at 160°C with an initial stirring rate of 250 rpm, an increasing stirring rate of 50 rpm / 10 min, and a final stirring rate of 400 rpm for 40 min to ensure complete melting and blending, resulting in a PA / POE / OBC mixture. Finally, the PA / POE / OBC mixture was further... 1g of h-BN was stirred at 160℃ for 250rpm for 30min until homogeneous, yielding a PA / POE / OBC / h-BN mixture. Then, 1g of EG was added to the PA / POE / OBC / h-BN mixture, and the mixture was stirred at 160℃ for 200rpm for 30min until homogeneous, yielding a PA / POE / OBC / h-BN / EG raw material. Finally, the PA / POE / OBC / h-BN / EG raw material was naturally cooled to room temperature from an initial temperature of 160℃ and then hot-pressed for 30min. After hot pressing, a PA / POE / OBC / h-BN / EG multi-component flexible phase change material block was obtained, referred to simply as the PA / POE / OBC / h-BN / EG block.
[0080] Example 2 This application provides a multi-component composite flexible phase change material and its preparation method, which includes the following steps: First, a certain amount of expandable graphite powder was microwave-expanded at 800W for 30 seconds to obtain EG. Then, 34g of PA was heated in a beaker at 80℃ until completely melted, and 2.5g of POE was added. The mixture was heated and stirred continuously at 130℃ at a rate of 350rpm for 1 hour to completely melt and blend, obtaining a PA / POE mixture. Next, 1.5g of OBC was added to the PA / POE mixture obtained above. The mixture was stirred at 165℃ with an initial stirring rate of 250rpm, an increasing stirring rate of 50rpm / 10min, and a final stirring rate of 400rpm for 40min to completely melt and blend, obtaining a PA / POE / OBC mixture. Finally, the PA / POE / OBC mixture was further stirred with... 1.2g of h-BN was stirred at 165℃ for 250rpm for 30min until homogeneous, yielding a PA / POE / OBC / h-BN mixture. Then, 0.8g of EG was added to the PA / POE / OBC / h-BN mixture, and the mixture was stirred at 165℃ for 200rpm for 30min until homogeneous, yielding a PA / POE / OBC / h-BN / EG raw material. Finally, the PA / POE / OBC / h-BN / EG raw material was naturally cooled to room temperature from an initial temperature of 165℃ and then hot-pressed for 30min. The hot-pressed material yielded a PA / POE / OBC / h-BN / EG multi-component flexible phase change material block, abbreviated as PA / POE / OBC / h-BN / EG block.
[0081] Example 3 This application provides a multi-component composite flexible phase change material and its preparation method, which includes the following steps: First, a certain amount of expandable graphite powder was microwave-expanded at 800W for 30 seconds to obtain EG. Then, 34g of PA was heated in a beaker at 80°C until completely melted, and 2g of POE was added. The mixture was heated and stirred continuously at 135°C at a rate of 400rpm for 1 hour to completely melt and blend, obtaining a PA / POE mixture. Next, 2g of OBC was added to the PA / POE mixture obtained above. The mixture was stirred at 170°C with an initial stirring rate of 250rpm, an increasing stirring rate of 50rpm / 10min, and a final stirring rate of 400rpm for 40min to completely melt and blend, obtaining a PA / POE / OBC mixture. Finally, 1g of POE / OBC was added to the PA / POE / OBC mixture. 4g of h-BN was stirred at 170℃ for 250rpm for 30min until homogeneous, yielding a PA / POE / OBC / h-BN mixture. Then, 0.6g of EG was added to the PA / POE / OBC / h-BN mixture, and the mixture was stirred at 170℃ for 200rpm for 30min until homogeneous, yielding a PA / POE / OBC / h-BN / EG raw material. Finally, the PA / POE / OBC / h-BN / EG raw material was naturally cooled to room temperature from an initial temperature of 170℃ and then hot-pressed for 30min. After hot pressing, a PA / POE / OBC / h-BN / EG multi-component flexible phase change material block was obtained, referred to simply as the PA / POE / OBC / h-BN / EG block.
[0082] Comparative Example 1 Comparative Example 1 of this application provides a phase change material, which is pure PA.
[0083] Comparative Example 2 This application provides a comparative example of a multi-component composite flexible phase change material and its preparation method, which includes the following steps: First, a certain amount of expandable graphite powder was microwave-expanded at 800W for 30 seconds to obtain EG. Then, 34g of PA was heated in a beaker at 80℃ until completely melted, followed by the addition of 4g of POE. The mixture was then heated and stirred continuously at 125℃ at 300rpm for 1 hour to ensure complete melting and blending, yielding a PA / POE mixture. Next, 1g of h-BN was added to the PA / POE mixture, and the mixture was stirred at 160℃ at 250rpm for 30 minutes until homogeneous, yielding PA / POE / h- BN mixture; then, 1g of EG is added to the PA / POE / h-BN mixture, and the mixture is stirred at 200rpm at 160℃ for 30min until it is uniformly mixed to obtain PA / POE / h-BN / EG raw material; finally, the PA / POE / h-BN / EG raw material is naturally cooled to room temperature at an initial temperature of 160℃ and then hot-pressed for 30min. After hot pressing, PA / POE / h-BN / EG multi-component flexible phase change material block is obtained, which is simply referred to as PA / POE / h-BN / EG block.
[0084] Comparative Example 3 This application provides a comparative example of a multi-component composite flexible phase change material and its preparation method, which includes the following steps: First, a certain amount of expandable graphite powder was microwave-expanded at 800W for 30 seconds to obtain EG. Then, 34g of PA was heated in a beaker at 80°C until completely melted, and 3g of POE was added. The mixture was then heated and stirred continuously at 125°C at a rate of 300rpm for 1 hour to ensure complete melting and blending, thus obtaining a PA / POE mixture. Next, 1g of OBC was added to the obtained PA / POE mixture. The mixture was stirred at 160°C with an initial stirring rate of 250rpm, a stirring rate increase rate of 50rpm / 10min, and a final stirring rate of 400rpm. Continue stirring for 40 minutes to completely melt and blend, obtaining a PA / POE / OBC mixture; then, add 2g of EG to the PA / POE / OBC mixture, and stir at 160℃ and 200rpm for 30 minutes until uniformly mixed, obtaining PA / POE / OBC / EG raw material; finally, after naturally cooling the PA / POE / OBC / EG raw material to room temperature at an initial temperature of 160℃, hot press it for 30 minutes, and after hot pressing, obtain a PA / POE / OBC / EG multi-component flexible phase change material block, simply referred to as PA / POE / OBC / EG block.
[0085] The phase transition temperature, latent heat of phase transition, thermal conductivity, paraffin retention rate and tensile strength of the multi-component composite flexible phase change materials of Examples 1-3 and Comparative Examples 2-3, as well as the phase change material of Comparative Example 1, were measured and the results are shown in Table 1.
[0086] The testing method is as follows: 1. Phase transition temperature and latent heat of phase transition The phase transition temperature and latent heat of phase transition of flexible phase change materials were tested using a differential scanning calorimeter (DSC214) from TA Instruments, USA. The test temperature range was 0-90℃, the nitrogen flow rate was 50 ml / min, and the heating / cooling rate of the sample was 5℃ / min. The phase transition temperature and latent heat of phase transition of the test sample were obtained by cumulative integration of the heat flow-temperature curves obtained by TA software.
[0087] 2. Thermal conductivity The thermal conductivity of the flexible phase change material was determined using a laser thermal conductivity meter (LFA457) from Netzsch Instruments, Germany. Triple parallel tests were performed at each test temperature point at room temperature to determine the thermal conductivity of samples with different contents of thermally conductive filler.
[0088] 3. Paraffin wax retention rate To investigate the morphological stability of the material, different experimental samples and comparative samples were placed in a constant-temperature oven at 60℃. Morphological changes during the heating process were observed, and the mass of the samples was measured using a fractional balance at 1 / 10,000 for 15 min, 30 min, 1 h, 2 h, and 4 h. Changes in mass reflect the stability of the material.
[0089] 4. Tensile strength Tensile tests were conducted on flexible phase change materials at room temperature using a GABOEPLEXOR500N dynamic thermomechanical analyzer from TA Instruments, Inc. (USA) with a 25N force sensor, to reflect the toughness of the materials.
[0090] Table 1. Performance of the phase change materials in Examples 1-3 and Comparative Examples 1-3
[0091] Please see Figures 3-7 As can be seen from Examples 1-3 of this application, the phase transition temperature of the multi-component composite flexible phase change material in Examples 1-3 is 45.8-46.42℃, the latent heat of phase change is 152.93-158.33J / g, the thermal conductivity is 1.314-1.481W / (m·K), the paraffin mass retention rate is 99.55%-99.64%, and the elongation at break is 98.24%-102.65%.
[0092] As can be seen from the comparison between Comparative Example 1 and Example 1, Comparative Example 1 uses pure PA as the phase change material, and the thermal conductivity of the multi-component composite flexible phase change material in Example 1 is higher than that of the phase change material in Comparative Example 1.
[0093] As can be seen from the comparison between Comparative Example 2 and Example 1, the olefin-free olefin block copolymer of the multi-component composite flexible phase change material of Comparative Example 2 has a lower paraffin retention rate than that of Example 1.
[0094] As can be seen from the comparison between Comparative Example 3 and Example 1, the multi-component composite flexible phase change material of Comparative Example 3 does not contain hexagonal boron nitride, and its thermal conductivity is lower than that of Example 1.
[0095] Please see Figure 8 The multi-component flexible phase change material of Example 1, after undergoing bending and torsional deformation, maintained good flatness after recovery, indicating that the multi-component flexible phase change material of Example 1 has good flexibility.
[0096] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. A multi-component composite flexible phase change material, characterized in that, The multi-component composite flexible phase change material includes a support framework, a phase change material, and a thermally conductive filler. The support framework forms a three-dimensional porous network structure, and the phase change material and the thermally conductive filler are loaded into the pores of the support framework by impregnation or adsorption. The supporting skeleton comprises olefin block copolymers, polyolefin thermoplastic elastomers, and cross-linked polymers formed by olefin block copolymers and polyolefin thermoplastic elastomers; the phase change material comprises paraffin wax; and the thermally conductive filler comprises hexagonal boron nitride and expanded graphite.
2. The multi-component composite flexible phase change material according to claim 1, characterized in that, The mass ratio of the supporting frame, the phase change material, and the thermally conductive filler is 3~5:13~16:1~2.
3. The multi-component composite flexible phase change material according to claim 1, characterized in that, The mass percentage of hexagonal boron nitride in the thermally conductive filler is 30%~70%, and / or; The expanded graphite in the thermally conductive filler has a mass percentage of 30% to 70%.
4. The multi-component composite flexible phase change material according to claim 1, characterized in that, The phase transition temperature of the multi-component composite flexible phase change material is 45.8~46.42℃, and / or; The latent heat of phase change of the multi-component composite flexible phase change material is 152.93~158.33 J / g, and / or; The thermal conductivity of the multi-component composite flexible phase change material is 1.314~1.481 W / (m·K), and / or; The paraffin mass retention rate of the multi-component composite flexible phase change material is 99.55%~99.64%, and / or; The elongation at break of the multi-component composite flexible phase change material is 98.24%~102.65%.
5. A method for preparing a multi-component composite flexible phase change material as described in any one of claims 1 to 4, characterized in that, The preparation method of the multi-component composite flexible phase change material includes mixing the supporting skeleton, the phase change material and the thermally conductive filler by melt blending to obtain PA / POE / OBC / h-BN / EG raw material, and hot pressing the PA / POE / OBC / h-BN / EG raw material into shape.
6. The method for preparing the multi-component composite flexible phase change material according to claim 5, characterized in that, The melt blending method includes: S1. The polyolefin thermoplastic elastomer and the molten paraffin are melt-blended to obtain a PA / POE mixture; S2. The obtained PA / POE mixture and the olefin block copolymer are melt-blended to obtain a PA / POE / OBC mixture; S3. The obtained PA / POE / OBC mixture and the hexagonal boron nitride are melt-blended to obtain a PA / POE / OBC / h-BN mixture; S4. The obtained PA / POE / OBC mixture and the expanded graphite are melt-blended to obtain the PA / POE / OBC / h-BN / EG raw material.
7. The method for preparing the multi-component composite flexible phase change material according to claim 6, characterized in that, The melt blending temperature in step S1 is 120~130℃, the initial stirring rate is 200~250rpm, the stirring rate increase rate is 50rpm / 10min, the final stirring rate is 400~500rpm, the stirring time is 1.0~1.5h, and / or; The melt blending temperature in step S2 is 160~170℃, the stirring rate is 300~400rpm, the stirring time is 30~40min, and / or; The melt blending temperature in step S3 is 160~170℃, the stirring rate is 250~300rpm, the stirring time is 30~40min, and / or; The melt blending temperature in step S4 is 160~170℃, the stirring rate is 150~200rpm, the stirring time is 30~40min, and / or; The hot pressing process involves preheating the PA / POE / OBC / h-BN / EG raw materials to 80°C, then naturally cooling them to below 60°C before hot pressing for 30-40 minutes.
8. The method for preparing the multi-component composite flexible phase change material according to claim 5, characterized in that, The mass ratio of the paraffin wax to the polyolefin thermoplastic elastomer is 6:1 to 12:1, and / or; The mass ratio of the PA / POE mixture to the olefin block copolymer is 18:1 to 18:2, and / or; The mass of the hexagonal boron nitride is 2-3% of the mass of the PA / POE / OBC / h-BN mixture, and / or; The mass of the expanded graphite is 2-3% of the mass of the PA / POE / OBC / h-BN / EG mixture.
9. The method for preparing the multi-component composite flexible phase change material according to claim 5, characterized in that, The expanded graphite is prepared by the following method: Expandable graphite powder was placed in an alumina crucible and heat-treated using a microwave method. Optionally, the heating power of the heat treatment is 600W~1000W, and the heating time is 30s~60s.
10. A battery module, characterized in that, The battery module includes a housing, a battery rack, and multiple power batteries. The battery rack is sleeved on the outside of the power batteries. The battery rack is made of a multi-component flexible phase change material as described in any one of claims 1 to 4 or any one of claims 5 to 9. The multiple power batteries are disposed in the housing.