A foam-metal coupled composite phase change material with both thermal management and electromagnetic shielding properties and its preparation method

Abstract

This invention relates to the field of high thermal conductivity composite phase change materials and electromagnetic shielding composite materials, and particularly to a foam metal coupled composite phase change material that combines thermal management and electromagnetic shielding, and its preparation method. This invention regulates the microstructure of zinc-based metal-organic gel (Zn-MOG) through coordination environment control. Relying on the three-dimensional porous framework and hydrogen bonding of Zn-MOG, the hierarchical adsorption structure of expanded graphite (EG), and the macroscopic physical constraints of the foam metal, a triple synergistic effect is achieved to suppress PEG phase change leakage and improve the material's shape stability. Simultaneously, the interfacial bonding of Zn-MOG, EG, and the foam metal forms a continuous and interconnected phonon transport channel, significantly reducing interfacial thermal resistance and substantially improving the thermal conductivity of the composite system. Furthermore, the ionic conductivity of Zn-MOG, the electron transport network of EG, and the conductive framework of the foam metal work synergistically to endow the material with highly efficient electromagnetic shielding performance, achieving integrated thermal management and electromagnetic protection functions.

Description

Technical Field

[0001] This invention relates to the field of high thermal conductivity composite phase change materials and electromagnetic shielding composite materials, and particularly to a foam metal coupled composite phase change material that combines thermal management and electromagnetic shielding, and its preparation method. Background Technology

[0002] Against the backdrop of the national strategy of deep integration between global energy transition and next-generation information technology, high-power electronic components in fields such as 5G communications, new energy vehicles, and high-efficiency data centers are rapidly developing towards miniaturization, integration, and high power density. The large amount of heat accumulation and electromagnetic interference generated during equipment operation are becoming increasingly prominent issues, not only reducing device performance and lifespan but also causing signal interference and safety hazards. There is an urgent need for integrated material solutions that combine efficient thermal management and electromagnetic shielding. High-efficiency thermal management materials and electromagnetic interference protection technologies have become key supports for ensuring the stable operation of electronic equipment, improving energy efficiency, and maintaining information security, attracting widespread attention from academia and industry.

[0003] Currently, thermal management of electronic devices mainly relies on air cooling, liquid cooling, and phase change material (PCM) cooling. Among these, PCMs are widely used in passive thermal management due to their ability to operate at a constant temperature without requiring additional power, being low-carbon and energy-efficient. Polyethylene glycol (PEG), as a commonly used PCM substrate, has a large latent heat of phase change and good chemical stability, but it also suffers from drawbacks such as easy leakage during phase change, low thermal conductivity, and lack of electromagnetic shielding, making it unable to meet the multifunctional requirements of high-power devices. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a foam metal-coupled composite phase change material that combines thermal management and electromagnetic shielding, and its preparation method, which solves the problems of PEG leakage, low thermal conductivity and lack of electromagnetic shielding. The foam metal-coupled composite phase change material prepared by this invention has high thermal conductivity, high shape stability and excellent electromagnetic shielding performance, which can meet the integrated protection requirements of high-power electronic devices.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a foam-metal coupled composite phase change material that combines thermal management and electromagnetic shielding, comprising the following steps: A coordination reaction is carried out by mixing a tricarboxylic acid ligand, an organozinc salt, and an alkaline aqueous system to obtain an aqueous solution of a zinc-based organometallic gel; the alkaline aqueous system consists of an alkaline substance and water; the amount of the alkaline substance is such that the theoretical pH value of the coordination reaction system is 7-14. The zinc-based metal organogel aqueous solution, molten polyethylene glycol and expanded graphite are mixed, and then the water in the resulting mixture is removed to obtain a composite phase change system; the composite phase change system includes 16-25 wt% zinc-based metal organogel, 3-5 wt% expanded graphite and the balance polyethylene glycol; The composite phase change system is filled into the pores of the foam metal to obtain a foam metal coupled composite phase change material that combines thermal management and electromagnetic shielding.

[0006] Preferably, the alkaline substance includes one or more of sodium hydroxide, sodium carbonate, and sodium acetate.

[0007] Preferably, the alkaline water system is a solid-liquid mixture or an aqueous solution of an alkaline substance.

[0008] Preferably, the foamed metal includes foamed copper, foamed nickel, or foamed iron-nickel.

[0009] Preferably, the porosity of the foamed metal is 10~40 ppi.

[0010] Preferably, the polyethylene glycol includes PEG2000.

[0011] Preferably, the tricarboxylated organic acid ligand comprises citric acid monohydrate; and the organic zinc salt comprises zinc acetate dihydrate.

[0012] Preferably, the molar ratio of the tricarboxylated organic acid ligand to the zinc ions in the organic zinc salt is 2:1.

[0013] Preferably, the coordination reaction takes 1 hour.

[0014] The present invention provides a foam metal coupled composite phase change material with both thermal management and electromagnetic shielding prepared by the preparation method described above, comprising a foam metal matrix and a composite phase change material filled in the foam metal matrix; the composite phase change material comprises 16-25 wt% zinc-based metal-organic gel, 3-5 wt% expanded graphite and the balance polyethylene glycol.

[0015] This invention provides a method for preparing a foam-metal coupled composite phase change material that combines thermal management and electromagnetic shielding, comprising the following steps: mixing a tricarboxylic acid ligand, an organozinc salt, and an alkaline aqueous system to perform a coordination reaction to obtain a zinc-based metal-organic gel aqueous solution; the alkaline aqueous system consists of an alkaline substance and water; the amount of the alkaline substance satisfies the theoretical pH value of the coordination reaction system as 7-14; mixing the zinc-based metal-organic gel aqueous solution, molten polyethylene glycol, and expanded graphite, and then removing the water from the resulting mixture to obtain a composite phase change system; the composite phase change system comprises 16-25 wt% zinc-based metal-organic gel, 3-5 wt% expanded graphite, and the balance being polyethylene glycol; filling the pores of the dried composite system into the foam metal to obtain the foam-metal coupled composite phase change material that combines thermal management and electromagnetic shielding.

[0016] This invention regulates the microstructure of zinc-based metal-organic gel (Zn-MOG) through coordination environment control. It leverages the three-dimensional porous framework and hydrogen bonding of Zn-MOG, the hierarchical adsorption structure of expanded graphite (EG), and the macroscopic physical constraints of the foam metal to synergistically suppress PEG phase transition leakage and improve the material's shape stability. Simultaneously, the interconnection of Zn-MOG, EG, and the foam metal forms a continuous phonon transport channel, significantly reducing interfacial thermal resistance and substantially improving the thermal conductivity of the composite system. Furthermore, the ionic conductivity of Zn-MOG, the electron transport network of EG, and the conductive framework of the foam metal work synergistically to endow the material with highly efficient electromagnetic shielding properties, achieving integrated thermal management and electromagnetic protection functions.

[0017] The results of the embodiments show that, under the premise of ensuring that the composite phase change material has a high latent heat of phase change, the optimal sample latent heat of phase change can reach 154.45 J / g, which is close to the latent heat of phase change of pure PEG2000; the thermal conductivity is significantly improved compared with pure PEG2000, reaching up to 4.505 W / mK, which is far superior to conventional composite phase change materials; when placed on a 70℃ constant temperature heating platform for 4 hours, it can still maintain its complete shape without collapse, with a low mass loss rate and excellent shape stability; at the same time, the material has an electromagnetic shielding effectiveness of more than 25dB in the X-band, and the shielding performance is further enhanced after foam metal coupling, which can meet the dual requirements of thermal management and electromagnetic interference protection of high-power electronic components. Attached Figure Description

[0018] Figure 1 SEM images of M-series and C-series samples, as well as pure PEG material and expanded graphite; Figure 2 Thermal conductivity diagrams for C-DI, C-14, C-13, C-12, C-10, C-8, C-Ni, C-FeNi, and C-Cu; Figure 3DSC thermal cycling test results for C-DI, C-14, C-13, C-12, C-10, C-8, and pure PEG materials; Figure 4 Photographs showing the leakage of C-DI, C-14, C-13, C-12, C-10, and C-8 after heating at 70°C for 4 hours; Figure 5 Mass retention rates of C-DI, C-14, C-13, C-12, C-10, and C-8 after heating at 70°C for 4 hours; Figure 6 Figures showing the loading of C-DI composite systems with different 30ppi foam metal loading; Figure 7 The thermal management performance test diagrams are for C-DI, C-Ni, C-FeNi and C-Cu samples, as well as pure PEG material. Figure 8 The electromagnetic shielding effectiveness test results are shown for C-DI, C-Ni, C-FeNi, and C-Cu samples. Detailed Implementation

[0019] This invention provides a method for preparing a foam-metal coupled composite phase change material that combines thermal management and electromagnetic shielding, comprising the following steps: A coordination reaction is carried out by mixing a tricarboxylic acid ligand, an organozinc salt, and an alkaline aqueous system to obtain an aqueous solution of a zinc-based organometallic gel; the alkaline aqueous system consists of an alkaline substance and water; the amount of the alkaline substance is such that the theoretical pH value of the coordination reaction system is 7-14. The zinc-based metal organogel aqueous solution, molten polyethylene glycol and expanded graphite are mixed, and then the water in the resulting mixture is removed to obtain a composite phase change system; the composite phase change system includes 16-25 wt% zinc-based metal organogel, 3-5 wt% expanded graphite and the balance polyethylene glycol; The composite phase change system is filled into the pores of the foam metal to obtain a foam metal coupled composite phase change material that combines thermal management and electromagnetic shielding.

[0020] Unless otherwise specified, all raw materials used in this invention are commercially available products well known in the art.

[0021] This invention involves mixing a tricarboxylic acid ligand, an organozinc salt, and an alkaline aqueous system to perform a coordination reaction, thereby obtaining an aqueous solution of a zinc-based organometallic gel.

[0022] In this invention, the tricarboxylic acid ligand preferably includes citric acid monohydrate; the organic zinc salt preferably includes zinc acetate dihydrate; and the molar ratio of the tricarboxylic acid ligand to the zinc ions in the organic zinc salt is preferably 2:1.

[0023] In this invention, the alkaline water system preferably consists of an alkaline substance and water; the alkaline substance includes one or more of sodium hydroxide, sodium carbonate, and sodium acetate, more preferably sodium hydroxide; the water is preferably deionized water. In this invention, different alkaline sources have different regulatory effects on the structure and properties of Zn-MOG. NaOH is the most preferred choice because the three-dimensional porous structure of Zn-MOG prepared in the alkaline environment formed by NaOH and deionized water is more moderate. This environment can effectively anchor PEG through coordination bonds and hydrogen bonds to suppress phase transition leakage, and can also minimize the restriction on PEG crystallization behavior, allowing more PEG molecules to maintain their complete solid-liquid phase transition capability. In this invention, the amount of the alkaline water system is calculated based on the reaction coefficient of acid-base neutralization between the organic acid and the alkaline solution.

[0024] In this invention, the alkaline system is either a solid-liquid mixture or an aqueous solution of an alkali. For example, in one embodiment of this invention, the alkaline system is an alkaline system composed of 7.87 wt% NaOH particles and 1M NaOH solution. The 7.87 wt% NaOH particles can theoretically neutralize the reaction system, while the 1M NaOH solution is used to regulate the coordination environment to the target pH value. Whether it is a solid-liquid mixture or an aqueous solution of an alkali, in the coordination reaction process, it is sufficient as long as the theoretically required pH value for the coordination environment is provided.

[0025] In this invention, the theoretical pH value of the coordination reaction is 7-14, and in specific embodiments it can be 7, 8, 9, 10, 11, 12, 13 or 14. In the actual reaction process, since alkaline substances are unlikely to react completely, the coordination reaction is actually carried out in an alkaline environment.

[0026] In this invention, the coordination reaction is preferably carried out at room temperature, i.e., without the need for additional heating or cooling; the coordination reaction time is preferably 1 hour. In this invention, the coordination reaction is preferably carried out under stirring conditions. This invention forms a zinc-based organometallic gel (Zn-MOG) through a coordination reaction.

[0027] After obtaining the zinc-based metal organogel aqueous solution, the present invention mixes the zinc-based metal organogel aqueous solution, molten polyethylene glycol and expanded graphite, and then removes the water in the resulting mixture to obtain a composite phase change system.

[0028] In this invention, the polyethylene glycol is preferably PEG2000.

[0029] In this invention, the mixing preferably includes: heating polyethylene glycol to a melt, then adding an aqueous solution of zinc-based metal organogel to the molten polyethylene glycol for a first stirring, followed by adding expanded graphite for a second stirring. In this invention, the first stirring rate is preferably 400-500 r / min, and the first stirring time is preferably 0.5-1 h. In this invention, the second stirring rate is preferably 700-800 r / min, and the second stirring time is preferably 2-3 h.

[0030] In this invention, the heating temperature to the melting point is preferably 80°C; the heating and mixing are preferably carried out in an oil bath.

[0031] In this invention, the removal of moisture from the resulting mixture is preferably achieved by vacuum drying. The vacuum drying temperature is preferably 80°C. The vacuum drying time is not specifically required; it can be carried out until the mixture is almost completely free of water. In an embodiment of this invention, vacuum drying is specifically performed for 24 hours.

[0032] In this invention, the composite phase change system comprises 16-25 wt% zinc-based organometallic gel, 3-5 wt% expanded graphite, and the balance polyethylene glycol. In specific embodiments, the content of zinc-based organometallic gel in the composite phase change system can be 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 wt%; and the content of expanded graphite can be 3, 4, or 5 wt%.

[0033] After obtaining the composite phase change system, the present invention fills the pores of the foam metal with the composite phase change system to obtain a foam metal coupled composite phase change material that has both thermal management and electromagnetic shielding.

[0034] In this invention, the foamed metal preferably includes foamed copper, foamed nickel, or foamed iron-nickel, and more preferably foamed copper. In this invention, the porosity of the foamed metal is preferably 10-40 ppi, and in specific embodiments it can be 10, 15, 20, 25, 30, 35, or 40 ppi.

[0035] In this invention, filling the pores of the composite phase change system into the foam metal preferably includes the following steps: impregnating the foam metal into the composite phase change system, and then pressing it into shape. This invention does not impose specific limitations on the pressing pressure, as long as the material is macroscopically flat. Through pressing, this invention ensures a smooth surface of the composite phase change material and, on the other hand, makes the components more tightly packed together.

[0036] The present invention provides a foam metal coupled composite phase change material with both thermal management and electromagnetic shielding prepared by the preparation method described above, comprising a foam metal matrix and a composite phase change material filled in the foam metal matrix; the composite phase change material comprises 16-25 wt% zinc-based metal-organic gel, 3-5 wt% expanded graphite and the balance polyethylene glycol.

[0037] In this invention, zinc-based metal organogel has a three-dimensional porous structure, which can anchor PEG through capillary forces and hydrogen bonding to improve the shape stability of the material; EG has high thermal conductivity and can construct a conductive and thermally conductive network, which can simultaneously improve heat dissipation and electromagnetic shielding performance; the macroscopic three-dimensional skeleton of foam metal can further enhance the heat transfer and electromagnetic shielding effect, achieving synergy between microscopic and macroscopic performance.

[0038] The following detailed description, in conjunction with embodiments, of the foam metal-coupled phase change material and its preparation method that combine thermal management and electromagnetic shielding provided by the present invention, should not be construed as limiting the scope of protection of the present invention.

[0039] Preparation Examples 1 to 5 are zinc-based organometallic gels prepared under different alkaline conditions: Preparation Example 1 (1) Citric acid monohydrate and zinc acetate dihydrate were added to an alkaline system consisting of 7.87 wt% NaOH particles (theoretically just enough to neutralize carboxyl groups) and deionized water at a molar ratio of 2:1. The mixture was magnetically stirred at room temperature for 1 h to obtain a Zn-MOG aqueous solution. The solution was dried in a vacuum drying oven at 80 °C for 24 h to remove residual moisture. Then it was pressed into a mold to obtain a zinc-based metal organogel, denoted as M-DI.

[0040] Preparation Example 2 The preparation process was exactly the same as in Preparation Example 1, except that the deionized water in the alkaline system was replaced with 1M NaOH solution (i.e., an alkaline system consisting of 7.87 wt% NaOH particles and 1M NaOH solution). The theoretical pH value of the coordination environment was 14, and the resulting sample was labeled as M-14.

[0041] Preparation Example 3 The preparation process was exactly the same as in Preparation Example 1, except that the deionized water in the alkaline system was replaced with 0.1M NaOH solution, the theoretical pH of the coordination environment was 13, and the resulting sample was labeled M-13.

[0042] Preparation Example 4 The preparation process was exactly the same as in Preparation Example 1, except that the deionized water in the alkaline system was replaced with 0.01M NaOH solution, the theoretical pH of the coordination environment was 12, and the resulting sample was labeled M-12.

[0043] Preparation Example 5 The preparation process was exactly the same as in Preparation Example 1, except that the alkaline system was replaced with 7.65 wt% NaOH particles, 0.89 wt% NaCO3, and deionized water. The theoretical pH value of the coordination environment was 10, and the resulting sample was labeled M-10.

[0044] Preparation Examples 6-11 illustrate the preparation of composite phase change materials: Preparation Example 6 (1) Add citric acid monohydrate and zinc acetate dihydrate in a molar ratio of 2:1 to an alkaline system consisting of 7.87 wt% NaOH particles and deionized water (theoretically just enough to neutralize the carboxyl group), and stir magnetically at room temperature for 1 h to obtain a Zn-MOG aqueous solution.

[0045] (2) Place 75wt% PEG2000 in an 80℃ oil bath and melt it completely. Add 21wt% Zn-MOG and stir at 400 r / min for 0.5h. Slowly add 4wt% EG and stir at 800 r / min for 2h until the system is homogeneous.

[0046] (3) The mixture was dried in a vacuum drying oven at 80°C for 24 hours to remove residual moisture and obtain a composite phase change system.

[0047] (4) The composite phase change system is filled into a mold (non-foam metal) and compacted with a flatbed press to obtain a shaped composite phase change material, denoted as C-DI.

[0048] Preparation Example 7 The preparation process was exactly the same as in Preparation Example 6, except that the deionized water in the alkaline system was replaced with 1M NaOH solution (i.e., an alkaline system consisting of 7.87 wt% NaOH particles and 1M NaOH solution). The theoretical pH value of the coordination environment was 14, and the resulting sample was labeled C-14.

[0049] Preparation Example 8 The preparation process was exactly the same as in Preparation Example 6, except that the deionized water in the alkaline system was replaced with 0.1M NaOH solution, the theoretical pH value of the coordination environment was 13, and the resulting sample was labeled C-13.

[0050] Preparation Example 9 The preparation process was exactly the same as in Preparation Example 6, except that the deionized water in the alkaline system was replaced with 0.01M NaOH solution, the theoretical pH of the coordination environment was 12, and the resulting sample was labeled C-12.

[0051] Preparation Example 10 The preparation process was exactly the same as in Preparation Example 6, except that the alkaline system was replaced with 7.65 wt% NaOH particles, 0.89 wt% Na2CO3, and deionized water. The theoretical pH value of the coordination environment was 10, and the resulting sample was labeled C-10.

[0052] Preparation Example 11 The preparation process was exactly the same as in Preparation Example 6, except that the alkaline system was replaced with 16.15 wt% CH3COONa and deionized water. The theoretical pH of the coordination environment was 8, and the resulting sample was labeled C-8.

[0053] Example 1 (1) Add citric acid monohydrate and zinc acetate dihydrate in a molar ratio of 2:1 to an alkaline system consisting of 7.87 wt% NaOH particles and deionized water, and stir magnetically at room temperature for 1 h to obtain a Zn-MOG aqueous solution.

[0054] (2) Place 75wt% PEG2000 in an 80℃ oil bath and melt it completely. Add 21wt% Zn-MOG and stir at 400 r / min for 0.5h. Slowly add 4wt% EG and stir at 800 r / min for 2h until the system is homogeneous.

[0055] (3) The mixture was dried in a vacuum drying oven at 80°C for 24 hours to remove residual moisture and obtain a composite phase change system.

[0056] (4) The composite phase change system is filled into 30ppi copper foam and compacted with a flat plate machine to fully fill the pores, thus obtaining a 30ppi copper foam coupled composite phase change material, labeled as C-Cu.

[0057] Example 2 The preparation process was exactly the same as in Example 1, except that the foam metal was replaced with 30ppi of foam nickel, and the resulting sample was labeled as C-Ni.

[0058] Example 3 The preparation process was exactly the same as in Example 1, except that the foam metal was replaced with 30ppi foamed iron-nickel, and the resulting sample was labeled as C-FeNi.

[0059] Characterization and performance testing This section characterizes the microstructure, thermal properties, thermal conductivity, shape stability, foam metal properties, thermal management, and electromagnetic shielding performance of the aforementioned composite phase change materials. The test results are as follows: (1) The microstructure and morphology of PEG2000, expanded graphite (EG), M-series samples, and C-series samples were characterized using a scanning electron microscope (SEM, Hitachi S-3400 N, Japan). The accelerating voltage was set to 20 kV. The results are shown in [Figure number missing]. Figure 1 .Depend on Figure 1 It can be seen that pure EG exhibits a typical layered honeycomb hierarchical structure, while Zn-MOG has a three-dimensional porous cross-linked network structure. In the optimal group C-DI sample, PEG is fully adsorbed in the pore structure of Zn-MOG and the interlayer structure of EG, with a dense and uniform microstructure, good dispersion of each component, and no obvious agglomeration or pore defects, which is conducive to the construction of a continuous and interconnected thermal and electrical transport network. The samples under other alkaline systems show significant differences in the regularity of micropores and the dispersion of components, indicating that the alkaline environment has a significant regulatory effect on the microstructure of composite phase change materials.

[0060] (2) The thermal conductivity of pure PEG2000, C-DI, C-14, C-13, C-12, C-10, C-8, C-Ni, C-FeNi, and C-Cu samples was tested using a hot disk thermal constant analyzer. The thermal conductivity of pure PEG2000 was only 0.40 W / mK. Figure 2 It can be seen that the thermal conductivity of all samples was significantly improved after composite processing. Among the composite phase change materials prepared under different alkaline environments, C-DI had the highest thermal conductivity, reaching 2.784 W / mK, which was significantly higher than that of C-14, C-13, C-12, C-10, and C-8, with thermal conductivity of 1.832 W / mK, 2.359 W / mK, 1.806 W / mK, 2.186 W / mK, and 1.926 W / mK, respectively. This indicates that the alkaline environment formed by NaOH and deionized water is more conducive to constructing efficient heat conduction pathways. Under the same pore size of 30 ppi, the thermal conductivity of C-Cu reached 4.505 W / mK, which was significantly higher than that of C-Ni and C-FeNi, with thermal conductivity of 2.805 W / mK and 2.989 W / mK, respectively. This shows that the intrinsic thermal conductivity of the 30 ppi copper foam composite system is optimal, which can significantly enhance the overall heat transfer capability.

[0061] (3) Differential scanning calorimetry (DSC) was used in a nitrogen atmosphere at a flow rate of 50 mL / min, with a heating rate set to 10 °C / min. The test temperature range was 0–80 °C. The phase transition properties of C-DI, C-14, C-13, C-12, C-10, C-8, and pure PEG2000 were tested. The test results are shown in [Figure number missing]. Figure 3 Phase transition temperature T of each sample m Phase transition latent heat The data for H and enthalpy efficiency λ are listed in Table 1.

[0062] Table 1. Latent heat of phase change of different composite phase change materials H, peak phase transition temperature T m Enthalpy efficiency λ

[0063] As shown in Table 1, the latent heat of phase change (LCH) of all composite phase change materials is lower than that of pure PEG2000 (183.62 J / g). This is because the physical dilution of PEG as the phase change functional substrate by Zn-MOG and EG components reduces the mass percentage of PEG2000 as the phase change component. Among them, C-DI has a LCH of 154.45 J / g and an enthalpy efficiency of 84.12%, significantly higher than C-14, C-13, C-12, C-10, and C-8. It is the group of components with the highest LCH and enthalpy efficiency among all samples, indicating stronger energy storage capacity. This is because the three-dimensional porous structure of Zn-MOG prepared in the alkaline environment formed by NaOH and deionized water is more temperate, effectively anchoring PEG through coordination bonds and hydrogen bonds to suppress phase change leakage, while minimizing restrictions on PEG crystallization behavior, allowing more PEG molecules to maintain their complete solid-liquid phase change capability. Figure 3 As can be seen, all samples exhibited obvious endothermic peaks within the characteristic phase transition temperature range of PEG, confirming that PEG2000 underwent a complete solid-liquid phase transition process in each composite system, retaining its intrinsic phase transition energy storage characteristics. The melting points of each composite sample were close to or slightly deviated from those of pure PEG2000, indicating that the composite systems prepared under different alkaline environments did not alter the intrinsic phase transition characteristics of PEG, with only slight fluctuations in melting point due to interactions between components.

[0064] (4) The composite phase change materials prepared in each embodiment were placed on a digital display constant temperature heating platform at 70°C and heated continuously for 4 hours. The initial interval was set to 0.5 hours, and then the mass and leakage of the samples were recorded every 1 hour thereafter. Before this, the mass of each sample and the image at room temperature were recorded. Figure 4 The graph reflects the corresponding leakage situation. As can be seen from the figure, after continuous heating at 70℃ for 4 hours, although all composite phase change materials showed varying degrees of leakage, they maintained their original shape without collapsing during this heating process. This demonstrates that the composite phase change materials possess good shape stability and leakage resistance. Figure 5 The specific values ​​show that the mass retention rate of the composite phase change materials is above 93%. These results clearly demonstrate that the capillary forces among EG, Zn-MOG, and PEG can reduce leakage of the composite phase change materials during the melting process. Thanks to the honeycomb layered structure of EG and the porous structure of Zn-MOG, the synergistic effect of EG and Zn-MOG can effectively adsorb PEG, limiting the migration and diffusion of PEG molecules in the molten state, resulting in excellent anti-leakage capability and shape stability, making it more suitable for long-term stable use under high-temperature conditions.

[0065] (5) The loading of C-Cu, C-Ni and C-FeNi supported C-DI composite systems was tested by weighing method. The results are shown in […]. Figure 6 .Depend on Figure 6 It can be seen that the loading rates of C-Cu, C-Ni, and C-FeNi on the C-DI composite system are 81.33%, 83.89%, and 83.01%, respectively, with very similar loading values ​​and no significant difference. This is because the three 30ppi foam metals have similar porosity and pore size distributions, and the three-dimensional interconnected porous framework provides sufficient filling space for the C-DI composite system. At the same time, their surface capillary adsorption and physical constraint capabilities are similar, so their loading capacity on the composite system is basically equivalent. The high loading rate characteristic enables foam metal-based composite phase change materials to encapsulate more phase change energy storage components within a limited volume, effectively improving the overall energy storage density.

[0066] (6) The thermal management performance of C-DI, C-Ni, C-FeNi, C-Cu samples and pure PEG2000 material (labeled C-01) was characterized using a self-built constant temperature thermal management test platform. Instantaneous high heat input was simulated using an external heat source, and the temperature rise and fall curves of each sample were recorded as follows: Figure 7 As shown. By Figure 7 Data shows that during the heating phase, the C-01 sample exhibited a significantly steeper heating slope than the other groups, resulting in the fastest temperature rise. It lacked a clear phase transition plateau, leading to rapid heat accumulation within the sample and the worst temperature control. In contrast, the C-DI, C-Ni, C-FeNi, and C-Cu samples showed similar heating slopes and distinct phase transition plateaus. This indicates that the introduction of the composite network constructed from Zn-MOG and EG, along with the further loading of three-dimensional porous foam metal, significantly improved the system's thermal conductivity and heat distribution uniformity. This allowed PEG2000 to undergo a phase transition and absorb latent heat simultaneously, effectively delaying the temperature rise. The C-Cu sample showed a slightly lower heating slope than the C-Ni and C-FeNi samples, suggesting that the 30ppi copper foam three-dimensional thermally conductive network was more efficient, transferring heat from the heat source to the system more effectively. This, combined with phase transition heat absorption, resulted in a more stable temperature rise and a rapid, uniform temperature drop during the cooling phase. This result demonstrates that the three-dimensional porous foam metal skeleton not only provides physical support for the composite phase change material, but more importantly, it constructs a highly efficient three-dimensional heat conduction network that can rapidly dissipate accumulated heat and effectively suppress temperature spikes in the central region. Combined with the thermal conductivity data in (2), it can be seen that C-Cu has the highest thermal conductivity, thus exhibiting the fastest heat transfer efficiency and the best temperature control effect. This result fully reflects the significant advantages of 30ppi foam copper-based composite phase change material in the thermal management application of high-power electronic devices. It can absorb heat through phase change energy storage and rapidly conduct heat away with the help of the metal skeleton, achieving dual high-efficiency temperature control, which can significantly improve the long-term stability and safety of electronic components.

[0067] (7) Electromagnetic shielding effectiveness of C-DI, C-Ni, C-FeNi and C-Cu samples was tested using a vector network analyzer in the X-band (8.2~12.5GHz) frequency range. The results are shown in […]. Figure 8 .Depend on Figure 8 Data shows that, compared with C-DI, the shielding effectiveness of the composite foam metal C-Ni, C-FeNi, and C-Cu samples is significantly improved, remaining stable above 25dB, demonstrating excellent electromagnetic shielding performance. This indicates that the foam metal, with its high conductivity and three-dimensional interconnected network, forms a highly efficient synergy with the C-DI system, significantly enhancing the absorption and attenuation of electromagnetic energy. The introduction of the three-dimensional foam metal framework constructs a continuous conductive network, utilizing the skin effect and eddy current loss mechanism to greatly improve electromagnetic shielding effectiveness, meeting the dual requirements of high-power electronic devices for comprehensive thermal and electromagnetic protection.

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a foam metal coupled composite phase change material with thermal management and electromagnetic shielding, characterized in that, Includes the following steps: A coordination reaction is carried out by mixing a tricarboxylic acid ligand, an organozinc salt, and an alkaline aqueous system to obtain an aqueous solution of a zinc-based organometallic gel; the alkaline aqueous system consists of an alkaline substance and water; the amount of the alkaline substance is such that the theoretical pH value of the coordination reaction system is 7-14. The zinc-based metal organogel aqueous solution, molten polyethylene glycol and expanded graphite are mixed, and then the water in the resulting mixture is removed to obtain a composite phase change system; the composite phase change system includes 16-25 wt% zinc-based metal organogel, 3-5 wt% expanded graphite and the balance polyethylene glycol; The composite phase change system is filled into the pores of the foam metal to obtain a foam metal coupled composite phase change material that combines thermal management and electromagnetic shielding.

2. The production method according to claim 1, characterized by, The alkaline substance includes one or more of sodium hydroxide, sodium carbonate, and sodium acetate.

3. The production method according to claim 1 or 2, characterized by, The alkaline water system is a solid-liquid mixture or an aqueous solution of an alkaline substance.

4. The method of claim 1, wherein, The foamed metal includes foamed copper, foamed nickel, or foamed iron-nickel.

5. The production method according to claim 1 or 4, characterized by, The porosity of the foamed metal is 10~40 ppi.

6. The method of claim 1, wherein, The polyethylene glycol includes PEG2000.

7. The preparation method according to claim 1, characterized in that, The tricarboxylic acid ligand includes citric acid monohydrate; the organic zinc salt includes zinc acetate dihydrate.

8. The preparation method according to claim 1 or 7, characterized in that, The molar ratio of the tricarboxylated organic acid ligand to the zinc ions in the organic zinc salt is 2:

1.

9. The preparation method according to claim 1, characterized in that, The coordination reaction took 1 hour.

10. The foam metal coupled composite phase change material with both thermal management and electromagnetic shielding prepared by the preparation method according to any one of claims 1 to 9, comprising a foam metal matrix and a composite phase change material filled in the foam metal matrix; wherein the composite phase change material comprises 16 to 25 wt% zinc-based metal-organic gel, 3 to 5 wt% expanded graphite and the balance polyethylene glycol.

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