A high thermal conductivity flexible composite phase change material, its preparation method and application

Abstract

A high thermal conductivity flexible composite phase change material, its preparation method, and its applications are disclosed, belonging to the field of new materials technology. This high thermal conductivity flexible composite phase change material is composed of 72-82 wt% organic solid-liquid phase change material, 17 wt% polymeric support material, and 1-3% thermal conductivity enhancer by mass percentage. The organic solid-liquid phase change material is a fatty acid-based phase change material, and the thermal conductivity enhancer is a carboxylated thermally conductive carbon material. These two components are assembled under supramolecular forces and uniformly composited with the polymeric support material. This high thermal conductivity flexible composite phase change material exhibits stable shape and can switch between rigid and flexible materials with temperature changes. It can be used in fields such as lithium battery cooling in high-temperature environments and building energy conservation. The synthesis process of this type of material is simple, its application is convenient, and it has broad application prospects.

Description

Technical Field

[0001] This invention relates to a highly thermally conductive flexible composite phase change material, its preparation method, and its application, which belongs to the field of new materials technology. Background Technology

[0002] With social development and rapid population growth, energy consumption is increasing at an ever-increasing pace. To address the energy crisis, developing efficient energy storage materials for energy harvesting and redistribution is an effective way to overcome uneven energy distribution and solve the mismatch between energy supply and demand. Phase change materials, which capture and reuse heat through latent heat absorption and release, are considered very promising energy storage materials, especially in the fields of thermal energy storage and temperature control.

[0003] Phase change materials (PCMs) have attracted much attention due to their simple structure, stable performance, low cost, and lack of additional consumption. During a phase change process, PCMs can absorb or release a large amount of latent heat while maintaining a nearly constant temperature. The large latent heat absorbed or released during this process, coupled with relatively small changes in temperature and volume, allows for temperature control within a certain range, thus protecting lithium batteries and contributing to building energy conservation. Lin et al. proposed an AlN-reinforced flexible CPCM for battery thermal management.

[0004] However, the inherent rigidity of organic solid-liquid phase change materials, their susceptibility to leakage, and their poor thermal conductivity limit their practical applications. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a class of highly thermally conductive flexible phase change materials, their preparation methods, and applications, thereby solving the inherent technical problems of crystalline rigidity, easy leakage, and poor thermal conductivity in existing organic solid-liquid phase change materials. This material is assembled from an organic solid-liquid phase change material and a thermal conductivity enhancer under supramolecular forces, and then uniformly composited with a polymer support material to obtain a composite phase change material with adjustable phase change temperature, stable shape, and high thermal conductivity flexibility, which can be used for cooling lithium batteries in high-temperature environments. Furthermore, because the thermal conductivity enhancer forms supramolecular forces with the organic solid-liquid phase change material, the thermal conductivity enhancer can be uniformly dispersed within the composite phase change material matrix, thus solving the problem of poor dispersion of the thermal conductivity enhancer and improving the thermal conductivity performance of the highly thermally conductive flexible composite phase change material. This material has a simple synthesis process, is convenient to apply, and has broad application prospects.

[0006] A highly thermally conductive flexible phase change material, comprising, by mass percentage, 72-82 wt% organic solid-liquid phase change material, 17-25 wt% polymeric support material, and 1%-3% thermal conductivity enhancer. The organic solid-liquid phase change material is a fatty acid-based phase change material, and the thermal conductivity enhancer is a carboxylated thermally conductive carbon material. These two materials are assembled under supramolecular forces and uniformly composited with the polymeric support material.

[0007] Preferably, the organic solid-liquid phase change material is composed of 80-82 wt% organic solid-liquid phase change material, 17-22 wt% polymer support material and 1-3% thermal conductivity enhancer by mass percentage; all of which have good cooling effect and meet thermal management requirements.

[0008] More preferably, the organic solid-liquid phase change material is composed of 82 wt% organic solid-liquid phase change material, 17 wt% polymeric support material and 1% thermal conductivity enhancer by mass percentage.

[0009] Preferably, the organic solid-liquid phase change material is one to three of the following: stearic acid, lauric acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid.

[0010] Preferably, the polymer phase change support material is one to three of the following: styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, polystyrene-poly(ethylene-butene)-polystyrene block copolymer, and polystyrene-poly(ethylene-propylene)-polystyrene block copolymer.

[0011] Preferably, the thermal conductivity enhancer is carboxylated carbon nanotubes and / or carboxylated graphene.

[0012] More preferably, the organic solid-liquid phase change material is lauric acid, the polymer-based phase change support material is SEBS, and the thermal conductivity enhancer is carboxylated carbon nanotubes.

[0013] More preferably, the organic solid-liquid phase change material is composed of 82 wt% lauric acid, 17 wt% SEBS and 1% carboxylated carbon nanotubes by mass percentage.

[0014] A method for preparing a high thermal conductivity flexible phase change material suitable for battery thermal management includes the following process steps: (1) weighing the organic solid-liquid phase change material, the thermal conductivity enhancer and the polymer support material according to the aforementioned mass percentages, and then vacuum drying them;

[0015] (2) The polymer support material and solvent are mixed at a molar ratio of 1:10-20 to obtain a homogeneous solution;

[0016] (3) Mix the organic solid-liquid phase change material with the thermal conductivity enhancer, and then stir after ultrasonication;

[0017] (4) Pour the mixture obtained in step (2) into the solution obtained in step (3), and then pour them together into a mold and place them in a vacuum drying oven for adsorption; place them in the air to allow the solvent to evaporate, and then place them in a vacuum drying oven to remove the residual solvent, thereby obtaining a high thermal conductivity flexible phase change material.

[0018] Furthermore, the steps include:

[0019] (1) The aforementioned organic solid-liquid phase change material, thermal conductivity enhancer and polymer support material by mass percentage were vacuum dried at 80°C for 48h;

[0020] (2) At 50°C, the polymer support material (17% to 25%) and the solvent are mixed at a molar ratio of 1:15 to obtain a homogeneous solution;

[0021] (3) After mixing the organic solid-liquid phase change material (80-82 wt%) with the thermal conductivity enhancer (1%-3%), sonicate for 1 hour, and then place the mixture in a beaker and stir for two hours;

[0022] (4) Pour the mixture obtained in step (2) into the solution obtained in step (3), and then pour them together into a mold. Place the mold in a vacuum drying oven for 2 hours to adsorb. Let the mixture be placed in the air for 48 hours to allow the solvent to evaporate. Finally, place the mixture in a vacuum drying oven for 24 hours to remove the residual solvent and obtain a high thermal conductivity flexible phase change material.

[0023] Preferably, in step (2), the solvent is one to three of the following: tetrahydrofuran, dioxane, petroleum ether, acetone, butanone, chloroform, dichloromethane, carbon tetrachloride, carbon disulfide, DMF, DMSO, benzene, toluene, xylene, nitrobenzene, chlorobenzene, cyclohexane, or n-hexane.

[0024] Another object of the present invention is to provide a battery thermal management device comprising the aforementioned highly thermally conductive flexible phase change material.

[0025] A battery thermal management device includes a battery and a highly thermally conductive flexible phase change material, wherein the highly thermally conductive flexible phase change material is attached to at least a portion of the battery surface.

[0026] Preferably, the highly thermally conductive flexible phase change material is attached to both sides of the battery with the largest area.

[0027] Furthermore, the device is applied in hot environments at high temperatures, reducing the operating temperature of a single soft-pack lithium-ion battery to below 50°C.

[0028] Furthermore, the battery operates in a temperature range of 20°C to 50°C.

[0029] Furthermore, the thickness of the phase change material in the battery thermal management device can be selected from 2 to 10 mm, preferably 4 to 6 mm, and most preferably 6 mm.

[0030] Another objective of this invention is to apply the aforementioned high thermal conductivity flexible phase change material to the field of building energy conservation. The prepared flexible composite phase change material with photothermal conversion function was filled into a constructed building model as a "thermal buffer" layer, and its "thermal buffer" effect compared to that without the addition of phase change material was tested.

[0031] The beneficial effects of this invention are as follows: The high thermal conductivity flexible phase change material disclosed in this invention, suitable for battery thermal management in high-temperature environments, is composed of an organic solid-liquid phase change material, a polymeric support material, and a thermal conductivity enhancer. The organic solid-liquid phase change material provides a cooling effect with its high melting point. The polymeric support material enables rigidity-flexibility transformation with temperature while preventing leakage of the organic solid-liquid phase change material. The phase change component in the high thermal conductivity flexible composite phase change material is assembled from the organic solid-liquid phase change material and the thermal conductivity enhancer under supramolecular forces, improving the dispersion of the thermal conductivity enhancer in the high thermal conductivity flexible composite phase change material matrix, thereby improving the thermal conductivity of the composite phase change material. It is also uniformly composited with the polymeric support material to form a high thermal conductivity flexible composite phase change material. When applied to battery thermal management in high-temperature environments, this high thermal conductivity flexible composite phase change material is attached to the two sides with the largest area of ​​the single battery cell. The high thermal conductivity flexible phase change material absorbs heat and controls the maximum temperature of the battery during operation to only 47.4℃, which is very close to the optimal operating temperature range of lithium batteries. However, without supramolecular interactions between the organic solid-liquid phase change material and other thermal conductivity enhancers, the composite phase change material formed by combining it with a polymer support material exhibits poor thermal management capabilities. This composite phase change material is attached to the two sides of the largest area of ​​the single battery cell, and its heat absorption limits the battery's maximum operating temperature to 55.0°C, exceeding the optimal operating temperature range of lithium batteries, making it unsuitable for use in high-temperature lithium battery thermal management systems. This invention fully utilizes the latent heat storage characteristics of phase change materials, enabling lithium-ion batteries to operate safely and efficiently in high-temperature environments. Therefore, it can be widely applied in battery thermal management systems to ensure battery performance and lifespan. Furthermore, this composite phase change material also possesses photothermal conversion properties, converting solar energy into thermal energy stored within the composite phase change material. The stored heat energy can then be released at appropriate times to insulate building walls, thus making it widely applicable in building energy conservation. Attached Figure Description

[0032] Figure 1 The image shows the infrared spectrum of the material in Example 1. Wherein, a) is lauric acid, b) is SEBS, c) is carboxylated carbon nanotubes, and d) is lauric acid / SEBS / carboxylated carbon nanotubes.

[0033] Figure 2 XRD curves of the materials in Example 1; where: a, lauric acid, b, SEBS, c, carboxylated carbon nanotubes, d, lauric acid / SEBS / carboxylated carbon nanotubes.

[0034] Figure 3 The DSC curves are for the materials in Example 1. Where: a) lauric acid, b) lauric acid / SEBS / carboxylated carbon nanotubes.

[0035] Figure 4 The shaping properties of the materials involved in Example 1 after heating at 50°C for 0-60 min are shown, wherein (a) lauric acid and (b) lauric acid / SEBS / carboxylated carbon nanotubes.

[0036] Figure 5 This describes the conversion between rigid and flexible materials using lauric acid / SEBS / carboxylated carbon nanotubes as described in Example 1, under conditions of 10-50°C.

[0037] Figure 6 This is a schematic diagram of the lauric acid-modified carboxylated carbon nanotubes involved in Example 1.

[0038] Figure 7 The infrared spectrum of the material involved in Example 1 is shown.

[0039] Figure 8 This describes the temperature control performance of the lauric acid / SEBS / carboxylated carbon nanotubes involved in Example 1 under high-temperature conditions. Specifically, (a) lauric acid / SEBS / carboxylated carbon nanotubes with a carboxylated carbon nanotube addition concentration of 1% and a thickness of 4 mm; (b) lauric acid / SEBS / carboxylated carbon nanotubes with a carboxylated carbon nanotube addition concentration of 2% and a thickness of 4 mm; (c) lauric acid / SEBS / carboxylated carbon nanotubes with a carboxylated carbon nanotube addition concentration of 3% and a thickness of 4 mm; and (d) lauric acid / SEBS / carboxylated carbon nanotubes with a carboxylated carbon nanotube addition concentration of 1% and a thickness of 6 mm.

[0040] Figure 9 The temperature control performance of the materials involved in Example 1 and the comparative examples under high temperature conditions is shown. Among them, (a) lauric acid / SEBS / carboxylated carbon nanotubes with an addition concentration of 1% and a thickness of 6 mm, and (b) lauric acid / SEBS / carbon nanotubes with an addition concentration of 1% and a thickness of 6 mm.

[0041] Figure 10This study examines the temperature control performance of the lauric acid / SEBS / carboxylated carbon nanotubes and the bare battery involved in Example 1 under high-temperature conditions. Specifically, (a) lauric acid / SEBS / carboxylated carbon nanotubes with a 1% concentration and a thickness of 6 mm were used at a 1C discharge rate; and (b) lauric acid / SEBS / carboxylated carbon nanotubes with a 1% concentration and a thickness of 6 mm were used at a 1.5C discharge rate.

[0042] Appendix Figure 11 The thermal insulation performance of the lauric acid / SEBS / carboxylated carbon nanotube material involved in Example 1 was tested in a building model. The prepared flexible composite phase change material with photothermal conversion function was filled into the constructed building model as a "thermal buffer" layer, and its "thermal buffering" effect compared to that without the added phase change material was tested. (a) shows the temperature rise and fall curves of the composite phase change material coated with lauric acid / SEBS / carboxylated carbon nanotubes, and (b) shows the temperature rise and fall curves of the composite phase change material without the coating. Detailed Implementation

[0043] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0044] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0045] One of the specific implementation methods:

[0046] A highly thermally conductive flexible phase change material, wherein the highly thermally conductive flexible phase change material is composed of the following components by mass percentage:

[0047] Organic solid-liquid phase change materials: 72–82 wt%;

[0048] Polymer support material: 17-25 wt%;

[0049] Thermal conductivity enhancer: 1%–3 wt%.

[0050] Preferably, the high thermal conductivity flexible phase change material of this invention is composed of the following components by mass percentage:

[0051] Organic solid-liquid phase change material: 82 wt%;

[0052] Polymer support material: 17wt%;

[0053] Thermal conductivity enhancer: 1 wt%.

[0054] The high thermal conductivity flexible phase change material of the present invention is preferably one to three of the following: stearic acid, lauric acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid.

[0055] The high thermal conductivity flexible phase change material of the present invention preferably uses one to three of the following polymer support materials: SIS, SBS, SEBS, and SEPS.

[0056] The thermal conductivity enhancer described in this invention is one to three of carbon nanotubes and carboxylated carbon nanotubes.

[0057] A method for preparing a highly thermally conductive flexible phase change material includes the following steps: First, a polymeric support material is dissolved in a solvent at 50°C for half an hour to obtain a homogeneous solution. Next, the organic solid-liquid phase change material is mixed with a thermal conductivity enhancer and sonicated for 1 hour. Then, the mixture is placed in a beaker and stirred for two hours. Subsequently, the two solutions are mixed together and poured into a mold, which is then placed in a vacuum drying oven for adsorption for 2 hours. The mixture is then left in air for 48 hours to allow the solvent to evaporate. Finally, it is placed in a vacuum drying oven for 24 hours to remove residual solvent, yielding a highly thermally conductive flexible phase change material suitable for battery thermal management.

[0058] In the above technical solution, the solvent is preferably one to three of the following: tetrahydrofuran, dioxane, petroleum ether, acetone, butanone, chloroform, dichloromethane, carbon tetrachloride, carbon disulfide, DMF, DMSO, benzene, toluene, xylene, nitrobenzene, chlorobenzene, cyclohexane, or n-hexane.

[0059] A battery thermal management device made of a highly thermally conductive flexible phase change material suitable for battery thermal management in high-temperature environments includes a battery, with the highly thermally conductive flexible phase change material suitable for battery thermal management attached to the two sides of the battery with the largest area.

[0060] The above-mentioned battery thermal management device is applicable to hot environments with high temperatures.

[0061] Preferably, the battery is a single-cell soft-pack lithium-ion battery.

[0062] The above-mentioned high thermal conductivity flexible phase change materials suitable for battery thermal management are used in the preparation of temperature control materials for lithium-ion single-cell batteries.

[0063] Another objective of this invention is to enable the application of the aforementioned high thermal conductivity flexible phase change material in the field of building energy conservation.

[0064] Example 1

[0065] (1) Lauric acid, carboxylated carbon nanotubes and SEBS were vacuum dried at 80°C for 48 h.

[0066] (2) At 50°C, SEBS and cyclohexane were mixed evenly at a molar ratio of 1:15 to obtain a homogeneous solution.

[0067] (3) After mixing lauric acid and carboxylated carbon nanotubes, sonicate for 1 hour, and then place the mixture in a beaker and stir for two hours; the amount of lauric acid added is 82 wt%, the amount of SEBS added is 17 wt%, and the amount of carboxylated carbon nanotubes added is 1 wt%.

[0068] (4) Subsequently, the mixture obtained in step (2) is poured into the solution obtained in step (3), and then the prepared mixture is poured into a mold (100*60*60mm in size) and left in the air for 48 hours to allow the solvent cyclohexane to evaporate. Finally, it is placed in a vacuum drying oven for 24 hours to remove residual cyclohexane, and a high thermal conductivity flexible phase change material with a size of 100*60*6mm is obtained.

[0069] Example 2

[0070] Lauric acid: 82 wt%; polymer support material: 17 wt%; carboxylated carbon nanotubes: 1%, with dimensions of 100*60*4 mm. Other conditions were the same as in Example 1.

[0071] Example 3

[0072] Lauric acid: 81 wt%; polymer support material: 17 wt%; carboxylated carbon nanotubes: 2%, with dimensions of 100*60*4 mm. Other conditions were the same as in Example 1.

[0073] Example 4

[0074] Lauric acid: 80 wt%; polymer support material: 17 wt%; carboxylated carbon nanotubes: 3%, with dimensions of 100*60*4 mm. Other conditions were the same as in Example 1.

[0075] Comparative Example

[0076] By using carbon nanotubes instead of carboxylated carbon nanotubes as thermal conductivity enhancers, a corresponding high thermal conductivity flexible phase change material was obtained, with other conditions consistent with Example 1.

[0077] From the infrared spectrum of the material (attached) Figure 1 As can be seen from the results, the infrared (curve d) of the obtained high thermal conductivity flexible composite phase change material (lauric acid / SEBS / carboxylated carbon nanotubes) does not show any new characteristic peaks compared with the infrared (curves a-c, a, lauric acid, b, SEBS, c, carboxylated carbon nanotubes), indicating that the two are physically mixed.

[0078] XRD characterization of materials (with appendix) Figure 2As can be seen, the crystallization peak of the obtained high thermal conductivity flexible composite phase change energy storage material is the same as the characteristic peak of lauric acid, indicating that it has crystallization characteristics. The DSC curve of the obtained high thermal conductivity flexible composite phase change energy storage material is attached. Figure 3 In the figure, (a) is lauric acid and (b) is lauric acid / SEBS / carboxylated carbon nanotubes. The phase change enthalpy of the resulting lauric acid / SEBS / carboxylated carbon nanotube high thermal conductivity flexible composite phase change energy storage material is lower than that of lauric acid. This is because the physically added SEBS and carboxylated carbon nanotubes do not have phase change properties. However, the phase change enthalpy of lauric acid / SEBS / carboxylated carbon nanotubes reaches 150.9 J / g, exhibiting good phase change heat storage characteristics.

[0079] Appendix Figure 4 In the figure, (a) represents lauric acid and (b) represents the change of lauric acid / SEBS / carboxylated carbon nanotubes with heating time. When the temperature is heated to 50℃ and the heating time is 15min, the lauric acid has begun to melt. However, the obtained lauric acid / SEBS / carboxylated carbon nanotube high thermal conductivity flexible composite phase change energy storage material remains solid and does not flow even when heated for 60min, indicating that the material has excellent shape-stabilized phase change characteristics.

[0080] Appendix Figure 5 It can be seen that lauric acid / SEBS / carboxylated carbon nanotubes exhibit high rigidity at 20℃, while exhibiting weaker rigidity at 30℃–40℃. However, at 40–50℃, lauric acid / SEBS / carboxylated carbon nanotubes can achieve a significant degree of bending, exhibiting flexibility. This ability to freely switch between rigid and flexible materials with temperature variations helps achieve device compactness within a limited space and improves thermal management efficiency.

[0081] Appendix Figure 6 This diagram illustrates the hydrogen bonding between carboxylated carbon nanotubes (CNTs) and lauric acid. CNTs have a large specific surface area and high surface energy, making them prone to aggregation and difficult to disperse in organic or inorganic solvents. Therefore, we used carboxylated CNTs and modified them with LA (Laminated Alcohol) to increase the dispersibility of CNTs-COOH. This is because the carboxyl groups in CNTs-COOH form hydrogen bonds with the carboxyl groups in LA, thereby increasing the dispersibility of CNTs-COOH.

[0082] Appendix Figure 7The images show the infrared spectra of lauric acid / SEBS / carboxylated carbon nanotubes and lauric acid / SEBS / carbon nanotubes. The figures show that the proportion of hydrogen-bonded C=O in LA / SEBS / CNTs is 24%, while the proportion of hydrogen-bonded C=O in LA / SEBS / CNTs-COOH increases to 37%. This indicates that carboxylated CNTs can form supramolecular forces with LA, thus allowing CNTs-COOH to be better dispersed in the phase transition system and improving its thermal conductivity.

[0083] Appendix Figure 8 The values ​​in 'ad' represent the highest operating temperatures of lithium-ion batteries coated with LA / SEBS / CNTs-COOH at different thicknesses and concentrations in Examples 1-4. (a) Lauric acid / SEBS / carboxylated carbon nanotubes with a concentration of 1% and a thickness of 4 mm; (b) Lauric acid / SEBS / carboxylated carbon nanotubes with a concentration of 2% and a thickness of 4 mm; (c) Lauric acid / SEBS / carboxylated carbon nanotubes with a concentration of 3% and a thickness of 4 mm; and (d) Lauric acid / SEBS / carboxylated carbon nanotubes with a concentration of 1% and a thickness of 6 mm. The results show that when the CNTs-COOH addition amount is 1% and the CPCM thickness is 6 mm, the CPCM exhibits the best cooling effect, meeting the thermal management requirements.

[0084] Appendix Figure 9 ab represents the highest operating temperature of lithium batteries when LA / SEBS / CNTs-COOH and LA / SEBS / CNTs are used in Example 1 and the comparative example. (a) Lauric acid / SEBS / carboxylated carbon nanotubes with a concentration of 1% and a thickness of 6 mm; (b) Lauric acid / SEBS / carbon nanotubes with a concentration of 1% and a thickness of 6 mm (prepared by the comparative example). As can be seen from the figure, the composite phase change material prepared by unmodified CNTs has poor thermal management performance, with a maximum operating temperature of 55.0℃, which exceeds the optimal operating temperature range of lithium batteries; while the CPCM prepared by modified CNTs-COOH has a maximum operating temperature of only 47.4℃.

[0085] Appendix Figure 10Figures a and b show a comparison of the maximum operating temperatures of lithium batteries with and without CPCM (Content-Coated Cell Modules) at different discharge rates (1C and 1.5C). (a) At 1C discharge rate, the concentration of carboxylated carbon nanotubes is 1%, and the thickness is 6mm (lauric acid / SEBS / carboxylated carbon nanotubes). (b) At 1.5C discharge rate, the concentration of carboxylated carbon nanotubes is 1%, and the thickness is 6mm (lauric acid / SEBS / carboxylated carbon nanotubes). The figures show that, regardless of the discharge rate, the operating temperature of the CPCM-coated lithium battery is lower than that of the uncoated one. Especially at 1.5C discharge rate, its operating temperature drops from 56.9℃ to 47.4℃. Therefore, it can be widely used in battery thermal management systems to ensure battery performance and lifespan.

[0086] Appendix Figure 11 This image compares the thermal insulation performance of building models with and without the composite phase change material. The prepared flexible composite phase change material with thermal insulation function was filled into the constructed building model as a "thermal buffer" layer, and its "thermal buffering" effect was compared with that without the flexible composite phase change material. Figure 11 As shown, within the same illumination heating time, the uncoated composite phase change material can only utilize the direct thermal effect of infrared light; although the temperature increases, it still cannot reach the phase change temperature. However, the composite phase change material exhibits a heating and cooling plateau, indicating its photothermal conversion performance. Thermal energy can be released through spontaneous phase transitions, thus completing the conversion between light and heat energy, which can be widely applied in building energy conservation.

[0087] The preparation method of this phase change material also includes:

[0088] Examples 5-8

[0089] By using stearic acid instead of lauric acid as the phase change material, a corresponding high thermal conductivity flexible phase change material was obtained, with other conditions consistent with those in Examples 1-4.

[0090] Examples 9-12

[0091] By using tetradecanoic acid instead of lauric acid as the phase change material, a corresponding high thermal conductivity flexible phase change material was obtained, with other conditions consistent with Examples 1-4.

[0092] Examples 13-16

[0093] By using hexadecanoic acid instead of lauric acid as the phase change material, a corresponding high thermal conductivity flexible phase change material was obtained, with other conditions consistent with those in Examples 1-4.

[0094] Examples 17-20

[0095] By using octadecanoic acid instead of lauric acid as the phase change material, a corresponding high thermal conductivity flexible phase change material was obtained, with other conditions consistent with those in Examples 1-4.

[0096] Examples 21-24

[0097] By using SIS instead of SEBS as the polymer support material, a corresponding high thermal conductivity flexible phase change material was obtained, with other conditions consistent with Examples 1-4.

[0098] Examples 25-28

[0099] By using SBS instead of SIS as the polymer support material, a corresponding high thermal conductivity flexible phase change material was obtained, with other conditions consistent with Examples 1-4.

[0100] Examples 29-32

[0101] By using SEPS instead of SIS as the polymer support material, a corresponding high thermal conductivity flexible phase change material was obtained, with other conditions consistent with Examples 1-4.

[0102] Examples 33-36

[0103] By using carboxylated graphene instead of carboxylated carbon nanotubes as a thermal conductivity enhancer, a corresponding high thermal conductivity flexible phase change material was obtained, with other conditions consistent with Examples 1-4.

[0104] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly thermally conductive flexible composite phase change material, characterized in that, The phase change component in the high thermal conductivity flexible composite phase change material is assembled from an organic solid-liquid phase change material and a thermal conductivity enhancer under supramolecular forces, and is uniformly composited with a polymer support material. The organic solid-liquid phase change material is a fatty acid-based phase change material, and the thermal conductivity enhancer is a carboxylated carbon nanotube and / or a carboxylated graphene. The composite phase change material is composed of 72%-82% organic solid-liquid phase change material, 17%-25% polymer support material, and 1%-3% thermal conductivity enhancer by mass percentage.

2. The composite phase change material according to claim 1, characterized in that: The organic solid-liquid phase change material is one to three of the following: stearic acid, lauric acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid.

3. The composite phase change material according to claim 1, characterized in that, The polymer support material is one to three of the following: styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, polystyrene-poly(ethylene-butene)-polystyrene block copolymer, and polystyrene-poly(ethylene-propylene)-polystyrene block copolymer.

4. A method for preparing a highly thermally conductive flexible composite phase change material according to any one of claims 1-3, characterized in that, The process includes the following steps: (1) Weigh the organic solid-liquid phase change material, the thermal conductivity enhancer and the polymer support material according to the mass percentages in claim 1, and dry them under vacuum; (2) The polymer support material and solvent are mixed at a molar ratio of 1:10-20 to obtain a homogeneous solution; (3) Mix the organic solid-liquid phase change material with the thermal conductivity enhancer, and then stir after ultrasonication; (4) Pour the mixture obtained in step (2) into the solution obtained in step (3), and then pour them together into a mold and place them in a vacuum drying oven for adsorption; place them in the air to allow the solvent to evaporate, and then place them in a vacuum drying oven to remove the residual solvent, thereby obtaining a high thermal conductivity flexible phase change material.

5. The preparation method according to claim 4, characterized in that, The solvent in step (2) is one or more of tetrahydrofuran, dioxane, petroleum ether, acetone, butanone, chloroform, dichloromethane, carbon tetrachloride, carbon disulfide, DMF, DMSO, benzene, toluene, xylene, nitrobenzene, chlorobenzene, cyclohexane, or n-hexane.

6. A battery thermal management device, comprising a battery and the high thermal conductivity flexible composite phase change material as described in any one of claims 1-3, wherein, A highly thermally conductive flexible composite phase change material is attached to at least part of the battery surface.

7. The apparatus according to claim 6, characterized in that, The highly thermally conductive flexible composite phase change material is attached to the two sides of the battery with the largest area.

8. The apparatus according to claim 6, characterized in that, The device is used in hot environments with high temperatures to reduce the operating temperature of a single soft-pack lithium-ion battery to below 50°C.

9. The high thermal conductivity flexible composite phase change material according to any one of claims 1-3 is applied to the field of building energy conservation.

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