High-thermal-conductivity composite fixed-phase change energy storage material and preparation method thereof

Abstract

The application discloses a high-thermal-conductivity composite shaped phase change energy storage material, which comprises the following components in percentage by weight: a phase change material 75-85%, a porous framework material 10-15%, an interface compatibility agent 3-5% and a shaped reinforcing agent 5-8%. The application further discloses a preparation method of the high-thermal-conductivity composite shaped phase change energy storage material. The porous framework material is used as a pre-designed functional framework, the phase change material is used as a filler, the shaped reinforcing agent is used as a special sealing layer, and the interface compatibility agent is used for modifying and improving interface compatibility, so as to jointly form a layered and multifunctional integrated composite system. The design can realize synchronous optimization of multiple key performance indexes such as thermal conductivity, leakage prevention, heat storage and stability.

Description

Technical Field

[0001] This invention belongs to the field of phase change energy storage technology, specifically relating to a high thermal conductivity composite shaped phase change energy storage material and its preparation method. Background Technology

[0002] Phase change energy storage technology, with its advantages of constant temperature during phase change, high heat storage density, and good energy storage stability, is widely used in many technical fields such as waste heat recovery, temperature-controlled energy storage, industrial energy conservation, and new energy thermal management. Solid-liquid phase change materials are currently the most widely used phase change energy storage materials. Among them, paraffin wax has become the mainstream solid-liquid phase change energy storage material for industrial applications due to its suitable phase change temperature, high latent heat, stable chemical properties, and low cost. However, pure paraffin wax-based solid-liquid phase change materials have two inherent technical defects: First, during the solid-liquid phase change, the liquid material has strong fluidity, which easily leads to leakage problems, seriously limiting the material's encapsulation, use, and long-term service stability; Second, paraffin wax has a low intrinsic thermal conductivity, usually below 0.3 W / m·K, resulting in a slow heat transfer rate and a lag in energy storage and heat release response, significantly reducing the working efficiency of phase change energy storage systems and restricting its widespread application in high-precision, high-efficiency thermal management scenarios.

[0003] To address the leakage and low thermal conductivity defects of paraffin-based solid-liquid phase change materials, the industry has explored various modification methods to optimize their performance. Currently, conventional unmodified phase change materials on the market generally have shortcomings in use. In actual encapsulation applications, these materials have weak thermal cycling resistance and are prone to morphological instability and insufficient heat transfer efficiency under long-term operating conditions, making them unsuitable for demanding industrial thermal management scenarios.

[0004] In summary, pure paraffin-based solid-liquid phase change energy storage materials have prominent inherent defects. A single phase change material cannot simultaneously meet the comprehensive requirements of leak prevention, high thermal conductivity, and long-cycle stability. Existing commercial phase change materials have poor adaptability. The industry urgently needs to develop a new type of high-performance, high-stability phase change energy storage composite material to fill the technological gaps in the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a high thermal conductivity composite shaped phase change energy storage material and its preparation method.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a high thermal conductivity composite shaped phase change energy storage material, comprising the following components by weight percentage: 75%-85% phase change material, 10%-15% porous framework material, 3%-5% interface compatibilizer, and 5%-8% shaped reinforcing agent.

[0008] In this invention, the porous framework material itself is an excellent thermal conductor, forming a highly efficient three-dimensional thermally conductive network; the macroscopic porous framework accommodates most of the phase change material through physical adsorption, and the shaping reinforcing agent can form an elastic layer on the surface of the phase change material, thus acting as a "valve" to seal the pores. The two work together to reduce weight loss; the interface compatibilizer modification improves the interface compatibility, and the elastic layer provides a buffer, improving the phase change enthalpy retention rate of the material after 1000 thermal cycles, without any shape change or performance degradation.

[0009] Preferably, the phase change material is a phase change energy storage host with a phase change enthalpy value higher than 180 J / g, and paraffin wax is preferred.

[0010] Preferably, the porous framework material is a three-dimensional porous boron nitride foam, a three-dimensional graphene foam, a metal foam, or a high thermal conductivity ceramic foam, with three-dimensional porous boron nitride foam being the most preferred.

[0011] Preferably, the interface compatibilizer is an aminosilane coupling agent, and more preferably, an aminosilane coupling agent such as KH-550 is used.

[0012] Preferably, the shaping and reinforcing agent is SEBS, SIS, TPU or POE, and more preferably hydrogenated styrene-butadiene block copolymer SEBS.

[0013] Secondly, this invention provides a method for preparing a high thermal conductivity composite shaped phase change energy storage material, comprising the following steps:

[0014] (1) Dissolve the interfacial compatibilizer in solvent A to obtain a solution of the interfacial compatibilizer;

[0015] (2) Immerse the porous framework material in the solution of the interface compatibilizer, disperse it by ultrasonication, take it out and dry it to obtain the surface-aminated porous framework material.

[0016] (3) Heat the phase change material to complete melting; completely immerse the surface-aminated porous framework material into the molten phase change material, dry it, and obtain a saturated composite material;

[0017] (4) Take out the above composite material, dissolve the shaping reinforcement in solvent B, and then coat it evenly on the surface of the composite material and the pore entrance; after removing the solvent, the shaping reinforcement forms an elastic sealing film on the surface of the composite material.

[0018] (5) The above materials are hot-pressed to obtain the final shaped phase change energy storage plate.

[0019] Preferably, in step (1), solvent A is an ethanol solution and the concentration of the interfacial compatibilizer is 1-10 wt%.

[0020] Preferably, in step (2), the ultrasonic power is 200-400W, the time is 20-40 minutes, and the temperature is 50-70℃.

[0021] Preferably, in step (2), ultrasonic dispersion is carried out in a constant temperature water bath.

[0022] Preferably, in step (2), the drying temperature is 75-85℃, the vacuum degree is -0.08--0.06 MPa, and the drying time is 5-7 hours.

[0023] Preferably, in step (3), the drying temperature is 20°C above the melting point of paraffin, the vacuum degree is -0.1 to -0.09 MPa, and the time is 1.5 to 2.5 hours.

[0024] Preferably, in step (4), solvent B is toluene, and the concentration of the shaping and reinforcing agent is 5-15 wt%.

[0025] Preferably, in step (4), solvent B is removed by evaporating the solvent at 55-57°C for 3-5 hours.

[0026] Preferably, in step (4), the coating is applied by spin coating or drop coating.

[0027] Preferably, in step (5), the hot pressing conditions are: holding the pressure at 75-85℃ and 4-6 MPa for 5-15 minutes.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] This invention uses a porous framework material as a pre-designed functional framework, a phase change material as a filler, a shaping and reinforcing agent as a dedicated sealing layer, and an interface compatibilizer to improve interfacial compatibility, together forming a layered, multifunctional integrated composite system. This design enables simultaneous optimization of multiple key performance indicators such as thermal conductivity, leak prevention, heat storage, and stability. The thermal conductivity of the composite material of this invention is increased to over 5 W / m·K, and it can maintain structural stability and leak-free operation during more than 1000 phase change cycles.

[0030] This invention effectively solves the problem of phase change material (PCM) precipitation during long-term use through a dual leak-proof mechanism of "physical locking + S-elastic sealing." PCM possesses high thermal conductivity, strong leak-proof properties, and long lifespan, making it ideal for applications with stringent requirements for heat dissipation and temperature uniformity. In power battery thermal management, this material can be made into thermal management sheets placed between battery cells to quickly dissipate heat, preventing heat accumulation and potentially reducing the maximum operating temperature of the battery pack while significantly improving temperature uniformity. Similarly, in solar thermal storage systems, its high thermal conductivity can accelerate the heat storage / release process, improving system efficiency; when used in building envelopes, it can enhance the temperature regulation capabilities of walls and improve energy-saving effects. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 is a diagram of the three-dimensional porous boron nitride molecular structure of the present invention;

[0033] Figure 2 shows the microstructure of the cross-section of the composite phase change material of the present invention.

[0034] Figure 3 is a comparison of the thermal conductivity of the example and the control group;

[0035] Figure 4 shows the DSC curve of the composite phase change material of the present invention;

[0036] Figure 5 shows a comparison of the leak-proof performance of the example and the control group at 85 degrees Celsius for 24 hours.

[0037] Figure 6 shows the phase change enthalpy retention rate of the composite phase change energy storage plate of the present invention under thermal cycling conditions of 50-70℃. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] This invention aims to overcome the technical defects of existing boron nitride-based phase change material technology, such as long-term cyclic leakage and anisotropic thermal conductivity, and to provide a novel high thermal conductivity composite shaped phase change energy storage material that can achieve simultaneous optimization of multiple key performance indicators such as thermal conductivity, leakage prevention, heat storage and stability.

[0040] This invention relates to a high thermal conductivity composite shaped phase change energy storage material, comprising the following components: 75%–85% phase change material, 10%–15% porous framework material, 3%–5% interface compatibilizer, and 5%–8% shape-stabilizing agent. The porous framework material is a pre-designed multifunctional framework, the phase change material acts as a filler, the shape-stabilizing agent forms an elastic layer on the material surface, and the interface compatibilizer modifies and improves interfacial compatibility. For example, the weight percentage of the phase change material may be, but is not limited to, 75%, 80%, or 85%; the weight percentage of the porous framework material may be, but is not limited to, 10%, 12%, or 15%; the weight percentage of the interface compatibilizer may be, but is not limited to, 3%, 4%, or 5%; and the weight percentage of the shape-stabilizing agent may be, but is not limited to, 5%, 6%, or 8%.

[0041] In some embodiments of the present invention, the phase change material is a phase change energy storage substrate with a phase change enthalpy higher than 180 J / g. Paraffin wax is preferred, as it is a mainstream solid-liquid phase change material with advantages such as high latent heat, stable properties, and low cost.

[0042] In some embodiments of the present invention, the porous framework material is a three-dimensional porous boron nitride foam, a three-dimensional graphene foam, a metal foam, or a high thermal conductivity ceramic foam. Preferably, a three-dimensional porous boron nitride foam is used. This three-dimensional porous boron nitride foam has an interconnected macroporous structure with a porosity of not less than 95%. This not only enables high-load adsorption of phase change materials, ensuring the composite material retains a high heat storage capacity, but also restricts the flow and seepage of liquid phase change materials through the interconnected pore structure, improving the stability of cyclic use. Simultaneously, the continuous framework constructed from interconnected hexagonal boron nitride nanosheets can build a uniform and interconnected thermally conductive network, weakening the anisotropy of thermal conductivity in the boron nitride sheets and reducing interfacial thermal resistance, thereby significantly improving the overall thermal conductivity of the composite material.

[0043] In some embodiments of the present invention, the interface compatibilizer is an aminosilane coupling agent used to modify the surface of the boron nitride framework and enhance its affinity with paraffin. KH-550 is preferred.

[0044] In some embodiments of the present invention, the shaping reinforcing agent is SEBS, SIS, TPU, or POE, which serves as an elastic network skeleton to further lock in the molten phase change material. Hydrogenated styrene-butadiene block copolymer SEBS is preferred.

[0045] This invention provides a method for preparing a high thermal conductivity composite shape-stabilized phase change energy storage material, comprising the following steps:

[0046] (1) Dissolve the interface compatibilizer in solvent A to obtain a solution of the interface compatibilizer; immerse the porous framework material in the solution of the interface compatibilizer, disperse it by ultrasonication, take it out and dry it to obtain a porous framework material with surface amination.

[0047] (2) Heat the phase change material to complete melting; completely immerse the surface-aminated porous framework material into the molten phase change material, dry it, and obtain a saturated composite material;

[0048] (3) Take out the above composite material, dissolve the shaping reinforcement in solvent B, and then coat it evenly on the surface of the composite material and the pore entrance; after removing the solvent, the shaping reinforcement forms an elastic sealing film on the surface of the composite material.

[0049] (4) The above materials are hot-pressed to obtain the final shaped phase change energy storage plate.

[0050] In some embodiments of the present invention, solvent A in step (1) is an ethanol solution, and the concentration of the interface compatibilizer is 1-10 wt%. This concentration is a commonly used and effective concentration for silane coupling agent treatment. If the concentration is too low, the modification effect will be insufficient; if the concentration is too high, the coupling agent molecules are prone to self-condensation, thus avoiding waste. For example, the concentration of the interface compatibilizer can be, but is not limited to, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc.

[0051] In some embodiments of the present invention, step (2) ultrasonic dispersion is carried out in a constant temperature water bath with an ultrasonic power of 200-400W, a time of 20-40 minutes, and a temperature of 50-70°C. This temperature is beneficial for the hydrolysis of the silane coupling agent (KH-550) and the condensation reaction with the hydroxyl groups on the BN surface, accelerating the reaction process and preventing the solvent from evaporating too quickly, which could lead to changes in solution concentration or uneven treatment. Under these ultrasonic conditions, the cavitation effect can be utilized to strongly drive the coupling agent solution into the deep pores of the three-dimensional porous foam, ensuring the uniformity and thoroughness of the modification reaction and guaranteeing a balance between treatment effect and energy / time cost. For example, the ultrasonic power can be, but is not limited to, 200W, 30W, or 400W; the ultrasonic time can be, but is not limited to, 20 minutes, 30 minutes, or 40 minutes; and the ultrasonic temperature can be, but is not limited to, 50°C, 60°C, or 70°C.

[0052] In some embodiments of the present invention, the drying temperature in step (2) is 75-85°C, the vacuum degree is -0.08--0.06 MPa, and the drying time is 5-7 hours. Vacuum-assisted melt impregnation and the vacuum environment of the drying conditions are beneficial for the thorough removal of residual ethanol, water, and reaction byproducts, ensuring safety. For example, the drying temperature may be, but is not limited to, 75°C, 80°C, or 85°C; the vacuum degree may be, but is not limited to, -0.08 MPa, -0.07 MPa, or -0.06 MPa; and the drying time may be, but is not limited to, 5 hours, 6 hours, or 7 hours.

[0053] In some embodiments of the present invention, the drying temperature in step (3) is 20°C above the melting point of paraffin wax, the vacuum degree is -0.1 to -0.09 MPa, and the time is 1.5 to 2.5 hours. This ensures that the paraffin wax fully penetrates every pore of the foam and significantly reduces its melt viscosity, improving fluidity. Under vacuum assistance, it can penetrate into the micro- and nano-sized pores of the BN foam more quickly and completely. If the temperature is too high, it may cause the paraffin wax to oxidize or thermally decompose; the vacuum degree must ensure that the paraffin wax boils and the pores are fully filled; and the drying time must ensure saturation impregnation. For example, paraffin wax with a melting point of 58°C is selected, and the drying temperature is 78°C; the vacuum degree can be, but is not limited to, -0.1 MPa, -0.095 MPa, or -0.09 MPa, etc.; and the drying time can be, but is not limited to, 1.5 hours, 2.0 hours, or 2.5 hours, etc.

[0054] In some embodiments of the present invention, solvent B in step (3) is toluene, and the concentration of the shaping reinforcing agent is 5-15 wt%. At this concentration, the film-forming properties and the permeability of the film can be balanced. Toluene is volatile and can be removed quickly. Specifically, the solvent is evaporated at 55-57°C for 3-5 hours. Under these conditions, its evaporation can be effectively accelerated, forming a dense SEBS elastic sealing film. This temperature is lower than the melting point of paraffin (58°C), which can ensure that the impregnated paraffin remains solid during the sealing process and prevents it from flowing out due to remelting. A sufficiently long drying time ensures that toluene is completely removed, avoiding solvent residue from affecting the stability of the material. For example, the concentration of the shaping reinforcing agent can be, but is not limited to, 5 wt%, 10 wt%, or 15 wt%, etc.; the evaporation temperature can be, but is not limited to, 55°C, 56°C, or 57°C, etc.; and the evaporation time can be, but is not limited to, 3 hours, 4 hours, or 5 hours, etc.

[0055] In some embodiments of the present invention, step (4) is performed by spin coating or drop coating.

[0056] In some embodiments of the present invention, the hot-pressing conditions of step (5) are as follows: holding the pressure at 75-85°C and 4-6 MPa for 5-15 minutes to ensure a tight bond between the elastic layer and the composite material. 80°C is used to reduce interface defects and further level and densify the SEBS layer. The hot-pressing temperature is much lower than the decomposition temperature of the shaping reinforcing agent and the porous skeleton material, which is a safe hot processing window. The selection of the hot-pressing pressure needs to eliminate any possible micro-gap, enhance the interface bonding force, and avoid crushing the fragile porous skeleton material structure. The selection of the holding time needs to ensure that the effects of heat and pressure are fully and evenly transferred to the entire material under the set temperature and pressure, ensuring that the elastic layer is fully softened, flows, and forms a firm and stable bond with the substrate, thus completing the final shaping. For example, the hot-pressing temperature can be, but is not limited to, 75°C, 80°C, or 85°C; the hot-pressing pressure can be, but is not limited to, 4 MPa, 5 MPa, or 6 MPa; and the hot-pressing time can be, but is not limited to, 5 min, 10 min, or 15 min.

[0057] Example

[0058] Raw material: n-alkane paraffin, type RT55, phase transition peak temperature 55℃, phase transition enthalpy ≥220 J / g.

[0059] Dosage: 800 grams.

[0060] Three-dimensional porous boron nitride foam, measuring 100mm × 100mm × 5mm in thickness, with a porosity ≥96%, is composed of macropores with diameters of 50–200μm, and its framework is formed by interconnected h-BN nanosheets. Dosage: Approximately 120 grams of paraffin can be adsorbed based on the corresponding pore volume.

[0061] γ-aminopropyltriethoxysilane KH-550, analytical grade.

[0062] Shaping reinforcement: hydrogenated styrene-butadiene block copolymer SEBS, dosage: 40 grams.

[0063] Preparation process:

[0064] Step 1: Prepare a 5 wt% KH-550 / ethanol solution: Weigh 5 grams of KH-550, dissolve it in 95 grams of anhydrous ethanol, stir magnetically for 30 minutes to mix it evenly, and cool it for later use.

[0065] Step 2: Completely immerse a three-dimensional porous boron nitride foam in the above solution, place the container in a 55°C constant temperature water bath, turn on the ultrasonic-assisted treatment power at 300W to promote silane hydrolysis and uniform adhesion to the BN skeleton surface; after 30 minutes, remove the foam and rinse it three times with anhydrous ethanol to remove the physically adsorbed coupling agent; place the rinsed foam in an 80°C vacuum drying oven and dry for 6 hours to obtain surface-aminated boron nitride foam for later use;

[0066] Step 3: Paraffin wax accounts for 83.33% of the total mass of the composite material. Place 800 grams of RT55 paraffin wax in a beaker and heat it in an oil bath at 80°C until it is completely melted into a transparent liquid. Set aside. Fix the boron nitride foam prepared in Step 1 into a special mold, and then completely immerse it below the surface of the molten paraffin wax. Place the entire mold in a vacuum drying oven, close the door, and start the vacuum pump to slowly reduce the pressure inside the oven to -0.095 MPa and maintain this vacuum level for 2 hours. During this process, tiny bubbles can be observed continuously escaping from the mold, indicating that the paraffin wax is replacing the air in the pores. After 2 hours, slowly release the vacuum and remove the mold. At this point, the foam has fully absorbed the paraffin wax, gaining approximately 120 grams in weight, and the boron nitride foam accounts for 12.5%, becoming a uniform white opaque block.

[0067] Step 4: Prepare a 10 wt% SEBS / toluene solution: Weigh 40 g of SEBS granules (the weight percentage of polystyrene segments in the SEBS granules is 4.17%) and add them to 360 g of toluene. Stir magnetically at 60°C for 4 hours until the SEBS is completely dissolved, forming a viscous, transparent solution. Set aside. Carefully remove the paraffin / boron nitride composite block obtained in Step 2 from the mold. Use a soft brush to evenly coat all surfaces of the composite block with the SEBS solution, ensuring that the solution can slightly penetrate the surface pores. Coat twice, and after each coating, let it stand in a fume hood for 15 minutes to allow some of the toluene to evaporate. Transfer the coated block to a 60°C forced-air drying oven and continue drying for 4 hours to ensure that the toluene completely evaporates, forming a dense SEBS elastic sealing film.

[0068] Step 5: Place the composite block that has been treated above into the mold of the flatbed hot press; set the hot press parameters: upper / lower plate temperature 80℃, pressure 5 MPa, holding time 10 minutes; start the hot pressing program to allow the SEBS layer to further level and densify under the action of heat and pressure, and to firmly bond with the composite material substrate; after the program is completed, allow it to cool naturally to room temperature and then demold to obtain the final composite shaped phase change energy storage plate.

[0069] control group

[0070] The control group sample was pure RT55 paraffin.

[0071] Performance testing

[0072] 1. Microscopic morphology analysis

[0073] Combined with appendix Figure 1 Three-dimensional porous boron nitride molecular structure diagram, and electron microscopy was used to characterize and observe the cross-sectional micromorphology of the prepared composite phase change material, such as... Figure 2 As shown. (From the appendix) Figure 1 It can be seen that the boron nitride raw material constructs a regular and interconnected three-dimensional network structure with uniform pore arrangement, providing sufficient space for phase change medium filling; microscopic test results Figure 2 The results show that the prepared three-dimensional boron nitride framework completely retains the pre-designed three-dimensional network structure, with no collapse or fracture defects. Paraffin wax is uniformly impregnated and fully fills the pores inside the boron nitride foam. The phase change material and the boron nitride framework are tightly bonded, and the interface between the two phases is dense, without obvious voids or gaps. This excellent composite interface structure demonstrates that the three-dimensional porous framework has excellent physical binding and encapsulation capabilities for paraffin wax, providing a solid structural foundation for achieving high stability and low leakage characteristics in the composite material.

[0074] 2. Thermal conductivity test

[0075] This experiment used a Netzsch LFA 467 laser flare thermal conductivity meter (Germany) to test the room-temperature thermal conductivity of the composite material. The test environment temperature was set at 25 ℃. (See attached image) Figure 3 The bar chart compares the thermal conductivity of pure RT55 paraffin and this composite material. As shown in the chart and test data, the thermal conductivity of pure RT55 paraffin is only about 0.2 W / m·K, while the thermal conductivity of this composite shape-stabilized phase change material reaches 7.5 W / m·K, demonstrating a significant improvement in thermal conductivity. This is because the continuous thermally conductive network formed by the overlapping boron nitride nanosheets effectively reduces interfacial thermal resistance, providing an efficient heat transfer channel for rapid heat conduction and completely overcoming the technical drawbacks of slow thermal conductivity and lag in thermal response of traditional phase change materials.

[0076] 3. Thermal storage performance analysis

[0077] The phase change thermal storage performance of the composite material was tested using a Netzsch DSC 214 Polyma differential scanning calorimeter. The heating rate was set to 5 °C / min, and the enthalpy change of the phase change was recorded under a standard test atmosphere. The test results are as follows: Figure 4 As shown, Figure 4 This indicates that the composite material has a phase change enthalpy of up to 168 J / g, demonstrating excellent thermal storage performance. The high-porosity three-dimensional boron nitride foam enables high paraffin loading, and the addition of a rigid skeleton does not significantly reduce the thermal storage capacity of the composite material. This allows the sample to balance excellent thermal conductivity with good thermal storage capacity, resulting in outstanding overall energy storage performance and suitability for industrial energy storage and thermal management applications.

[0078] 4. High-temperature leak-proof performance test

[0079] To evaluate the high-temperature setting and leakage resistance of the composite material, samples were placed in an 85 ℃ constant-temperature oven for 24 h. Leakage was assessed by weighing combined with observation of the surface morphology. After the test, the samples remained intact, with no grease exudation or obvious wetting marks on the surface; the calculated sample mass loss rate was less than 0.3%. Figure 5 As can be seen from the extremely low mass loss rate of the composite material of the present invention, the three-dimensional through-pore structure of the present invention, combined with the encapsulation system, can effectively bind molten paraffin, suppress the seepage of phase change materials under high temperature conditions, and has excellent high temperature resistance, leak prevention and structural stability.

[0080] 5. Thermal cycling stability test

[0081] Accelerated thermal cycling durability testing of the composite material was conducted using a programmed temperature-controlled constant temperature chamber. The cycling temperature range was set between 50℃ and 70℃ to simulate the actual service conditions of long-term repeated melting and solidification of the material. (Attached) Figure 6 The graph shows the phase change enthalpy retention rate of the composite phase change energy storage material under thermal cycling conditions of 50–70℃. Combined with the test data, the graph shows that after 1000 thermal cycles, the phase change enthalpy retention rate is higher than 94.5%. Furthermore, after the cycling test, the sample showed no deformation, oil leakage, or structural damage, indicating extremely low performance degradation. These results demonstrate that the composite phase change material exhibits excellent thermal reversible stability, stable energy storage performance during long-term service, and possesses excellent engineering service life and cycle reliability.

[0082] Based on the aforementioned test results, it can be seen that the composite material prepared by this invention, relying on the advantages of the three-dimensional boron nitride porous structure, takes into account high thermal conductivity, high heat storage, low leakage, and long cycle stability. All performance indicators are superior to traditional paraffin phase change materials, and the overall application performance is excellent, making it valuable for large-scale engineering applications.

[0083] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

Claims

1. A high thermal conductivity composite shape-stabilized phase change energy storage material, characterized in that, It includes the following components by weight percentage: phase change material 75%–85%, porous framework material 10%–15%, interface compatibilizer 3%–5%, and shape-stabilizing agent 5%–8%.

2. The phase change energy storage material according to claim 1, characterized in that: The phase change material is paraffin.

3. The phase change energy storage material according to claim 1, characterized in that: The porous framework material is a three-dimensional porous boron nitride foam, a three-dimensional graphene foam, a metal foam, or a high thermal conductivity ceramic foam.

4. The composite phase change material according to claim 1, characterized in that: The interface compatibilizer is an aminosilane coupling agent.

5. The composite phase change material according to claim 1, characterized in that: The shaping and reinforcing agent is SEBS, SIS, TPU, or POE.

6. A method for preparing a high thermal conductivity composite shape-stabilized phase change energy storage material as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Dissolve the interfacial compatibilizer in solvent A to obtain a solution of the interfacial compatibilizer; (2) Immerse the porous framework material in the solution of the interface compatibilizer, disperse it by ultrasonication, take it out and dry it to obtain the surface-aminated porous framework material. (3) Heat the phase change material to complete melting; completely immerse the surface-aminated porous framework material into the molten phase change material, dry it, and obtain a saturated composite material; (4) Take out the above composite material, dissolve the shaping reinforcement in solvent B, and then coat it evenly on the surface of the composite material and the pore entrance; after removing the solvent, the shaping reinforcement forms an elastic sealing film on the surface of the composite material. (5) The above materials are hot-pressed to obtain the final shaped phase change energy storage plate.

7. The preparation method according to claim 6, characterized in that: In step (1), solvent A is an ethanol solution, and the concentration of the interfacial compatibilizer is 1-10 wt%.

8. The preparation method according to claim 6, characterized in that: In step (2), the ultrasonic power is 200-400W, the time is 20-40 minutes, and the temperature is 50-70℃.

9. The preparation method according to claim 6, characterized in that: In step (4), solvent B is toluene, and the concentration of the shaping and reinforcing agent is 5-15 wt%.

10. The preparation method according to claim 6, characterized in that: In step (2), the drying temperature is 75-85℃, the vacuum degree is -0.08-0.06 MPa, and the drying time is 5-7 hours; in step (3), the drying temperature is 20℃ above the melting point of paraffin, the vacuum degree is -0.1-0.09 MPa, and the time is 1.5-2.5 hours.

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