A 3D conductive network structure heat-conducting and wave-absorbing disk material and its preparation method and application

Abstract

The present invention discloses a thermally conductive, wave-absorbing disc material with a 3D conductive network structure, its preparation method, and its application, belonging to the field of thermal conductive and wave-absorbing technology. The thermally conductive, wave-absorbing disc material is a composite of carbon fibers and magnetic nanoparticles (FeO, Fe3O4), prepared using an ionic crosslinking freeze-drying-calcination process. Not only is its structure and formation mechanism novel, but disc-shaped structures with varying magnetic material phases, textures, and compositions can also be prepared by varying the calcination temperature and crosslinker mass fraction. The preparation method disclosed in the present invention is simple to operate, produces novel product morphology, and exhibits excellent thermal conductivity, wave-absorbing, and shielding properties. This method overcomes the harsh reaction conditions, difficult-to-control texture and composition of the reaction products, and poor experimental reproducibility associated with previous preparation processes, and has great potential for industrial application.

Description

Technical Field

[0001] The present invention belongs to the field of thermal conductivity and wave absorption technology, and relates to a method for preparing a thermal conductivity and wave absorption disk material with a 3D conductive network structure and its application in microwave absorption and shielding, thermal management, sensors, supercapacitors, photocatalysis or lithium-ion batteries. Background Art

[0002] Integrated thermally conductive and absorbing materials can both conduct heat and effectively absorb and attenuate incident electromagnetic wave energy, playing a significant role in areas such as weapon stealth, human protection, and electronic product protection. Currently, research on integrated thermally conductive and absorbing materials is primarily focused on a separate basis. Research on integrated thermally conductive and absorbing materials started relatively late, with more research focusing on ceramics. However, research on polymer-based integrated thermally conductive and absorbing materials is limited and exhibits poor performance. Commonly used thermally conductive and absorbing fillers include thermally conductive insulating and thermally conductive conductive fillers. The former, primarily composed of metal oxides (MgO, Al2O3, SiO2, BeO), carbides (SiC), and nitrides (AlN, BN, Si3N4), are wave-transmitting materials and lack the required electromagnetic wave absorption. The latter, primarily composed of metal powders (Al, Ag, Cu, Au, Ni) and carbon-based materials (graphite, carbon fiber, carbon nanotubes, graphene), are reflective shielding materials with low absorption and poor voltage withstand capability. Their thermal conductivity depends on the type, loading, size, and shape of the thermally conductive filler. At present, there are few reports on the preparation of thermally conductive and absorbing disk materials with 3D conductive network structures and their thermal conductivity, absorption / shielding properties.

[0003] Disc-shaped / bowl-shaped micro / nanomaterials are biocompatible and mildly cross-linkable, with large contact areas and short ion transport distances. They have broad application prospects in drug release, protein, antibody, and cell encapsulation, novel optical materials, and electrochemical materials. However, their use as thermal conductive, microwave-absorbing, or shielding materials has not yet been reported. Currently, Hu Yuandu uses microfluidic single-emulsion and double-emulsion techniques, using Ba(Ac)2 aqueous solutions containing varying glycerol concentrations as cross-linkers. By varying the glycerol concentration in the cross-linker and the distance between the end of the collection tube and the collection liquid surface, he modulates the morphology of sodium alginate-based microgel particles. He has synthesized sodium alginate-based microgels with morphologies ranging from hemispherical to mushroom-shaped and flattened to flying saucer-shaped. This method requires extensive preparation and is relatively complex.

[0004] Chinese patent document (CN112961649A) discloses the preparation and application of a hollow bowl-shaped N@Co@C material, which uses hollow bowl-shaped sulfonated polystyrene microspheres and 2-methylimidazole as raw materials, anhydrous ethanol as the reaction solvent, and the precursor is obtained by reaction and then calcined to obtain a composite material. Some of the raw materials used in this method have certain hazards to the human body and the environment and do not meet the requirements of green environmental protection. Chinese patent document (CN111908514A) provides a preparation method and product of a bowl-shaped C-doped magnetic hollow mesoporous nanomaterial, which uses acrylamide and styrene as raw materials to prepare a bowl-shaped polystyrene / acrylic acid core, encapsulates iron ions, adjusts the pH, separates, washes, freeze-dried, and then calcined and carbonized. Although the bowl-shaped carbon nanoparticles prepared by this method are recyclable, economical and environmentally friendly, the preparation process is time-consuming and complicated, which is not conducive to industrialization. The above-mentioned bowl-shaped micro-nanomaterial preparation method is relatively complex, and the components are relatively simple, and it cannot simultaneously take into account thermal conductivity and wave absorption / shielding properties.

[0005] In recent years, with the adoption of 5G mobile technology, electromagnetic wave frequencies have increased, and electronic device components have become increasingly miniaturized and integrated. Addressing electromagnetic interference and heat dissipation is a pressing issue. Combining thermally conductive and absorbing materials to achieve both thermal conductivity and absorption is an effective solution. However, existing thermally conductive and absorbing disc materials are difficult to control in terms of composition, texture, and structure, resulting in a complex preparation process. Furthermore, they lack the ability to achieve both high absorption and thermal conductivity.

[0006] Therefore, how to develop a heat-conducting and wave-absorbing disk material with a simple process, easy industrialization, controllable morphology and size, and excellent performance with a 3D conductive network structure is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0007] The present invention aims to provide a thermally conductive, wave-absorbing disc material with a 3D conductive network structure, as well as its preparation method and application. The provided ion-crosslinking freeze-drying-calcination process offers advantages such as simple equipment, short cycle times, good repeatability, and scalable production. The prepared thermally conductive, wave-absorbing disc material exhibits adjustable texture, size, and composition within the 3D conductive network structure, and has broad application prospects in microwave absorption and shielding, thermal management, electrode materials, electrocatalysis, surface-enhanced Raman spectroscopy, photoelectric conversion, and gas sensing.

[0008] In order to achieve the above objectives, the present invention discloses the following:

[0009] The first technical purpose of the present invention is to provide a thermally conductive and absorbing disc material with a 3D conductive network structure, which is prepared by an ion crosslinking freeze drying-calcination process; the structure of the thermally conductive and absorbing disc material with a 3D conductive network structure is disc-shaped, and it is a composite of mutually cross-linked carbon fibers and magnetic nanoparticles (FeO, Fe3O4) to form a 3D conductive network structure, and its diameter is 1501 to 1892 μm, the carbon fiber content is 48.99 to 78.02%, and the magnetic nanoparticle content is 21.98 to 51.01%.

[0010] Preferably, the preparation operation of the ion crosslinking freeze drying-calcination process is as follows:

[0011] A natural polysaccharide aqueous solution of a certain concentration is placed under room temperature for hydrolysis to form sol A; a cross-linking agent and a surfactant are weighed, dissolved in deionized water, and stirred to form solution B; sol A is uniformly injected into solution B using a syringe pump to form a disc material; the disc material is soaked and washed with water and ethanol, respectively, and freeze-dried to obtain a xerogel; and then calcined, the cross-linking agent is carbon-thermally reduced to generate magnetic particles, the natural polysaccharide is decomposed into carbon fibers, and the magnetic particles are wrapped to obtain the thermally conductive and wave-absorbing disc material with the 3D conductive network structure.

[0012] The present invention discloses a heat-conducting and wave-absorbing disc material with a 3D conductive network structure prepared by an ion cross-linking freeze-drying-calcination process. The material not only has a novel structure and formation mechanism, but can also prepare disc-shaped structures with different magnetic material phases, textures, and contents by adjusting the calcination temperature and the mass fraction of the cross-linking agent. The disc-shaped structure has a diameter of 1501 to 1892 μm. In addition, due to the characteristics of the three-dimensional network structure and well-developed pores, the disc material can provide sufficient active sites for electrochemical reactions in the field of electrochemistry, thereby optimizing electrode performance. At the same time, its cross-linking properties can also be effectively combined with other metal particles, giving the heat-conducting and wave-absorbing disc material unique properties, showing great potential in the fields of heat conduction, wave absorption / shielding.

[0013] In addition, the thermally conductive and absorbing disc material with a 3D conductive network structure disclosed in the present invention has excellent thermal conductivity, microwave absorption and shielding properties. The thermal conductivity of the silicone rubber compound with a filling ratio of 30-40% is 4.11-5.5W / (m·K); the maximum effective bandwidth of the paraffin compound with a filling ratio of 20-50% is less than or equal to -10dB reflectivity is 7.2-16.96GHz, the maximum absorption is -37.30-55.13dB, and the thickness is 2.4-3.6mm; the shielding effectiveness can reach 54.46dB.

[0014] The second technical purpose of the present invention is to provide a method for preparing a disc-shaped heat-conducting and wave-absorbing disc material that is green, environmentally friendly, and suitable for industrial production.

[0015] A method for preparing a heat-conducting and wave-absorbing disk material with a 3D conductive network structure, the method specifically comprising the following steps:

[0016] (1) A certain concentration of natural polysaccharide aqueous solution was stirred for 4 h to form a solution, which was then allowed to stand for a period of time to hydrolyze to form sol A;

[0017] (2) Weigh the crosslinker and surfactant and dissolve them in deionized water. Stir for 10 to 30 minutes to form a crosslinker solution B. Use a syringe pump to evenly inject sol A into the crosslinker solution B to form a disc material.

[0018] (3) The disc material was washed by soaking in water and ethanol for 1 h, respectively, and then freeze-dried at -30°C to -60°C for 20-40 h to obtain a xerogel;

[0019] (4) The dry gel is loaded into an ark, placed in a tube furnace, and kept warm at a certain temperature under the protection of an inert gas to obtain the heat-conducting and wave-absorbing disk material with the 3D conductive network structure.

[0020] By adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0021] The preparation method disclosed in the present invention is simple to operate and has a novel product morphology, which overcomes the characteristics of harsh reaction conditions, difficult to control the morphology of the reaction product, and poor experimental repeatability in the previous preparation process, and has good potential for industrial application.

[0022] Preferably, the natural polysaccharide in step (1) is one of sodium alginate and potassium alginate, and the concentration is 0.04-0.08 mol / L.

[0023] Preferably, the surfactant in step (2) is at least one of polyethylene glycols (PEG400-20000) of different molecular weights, and its concentration in water is 0.0416-0.381 mol / L.

[0024] Preferably, the cross-linking agent in step (2) is at least one of soluble ferric chloride, nickel chloride, ferric sulfate, nickel sulfate, and cobalt sulfate, the mass fraction of which in water is 4% to 16%, and the mass ratio of the cross-linking agent to the surfactant is 2:1.

[0025] Preferably, the needle of the syringe pump in step (2) is a single-hole needle with a diameter of 0.18 to 0.45 mm, which is 4 to 10 cm above the liquid level of the cross-linking agent solution B; or the needle of the syringe pump is a coaxial double-hole needle with an inner diameter of 0.34 to 0.72 mm and an outer diameter of 0.92 to 1.43 mm; which is 4 to 10 cm above the liquid level of the cross-linking agent solution B;

[0026] Preferably, the calcination temperature in step (4) is 600° C. to 800° C., the calcination time is 2 to 4 hours, the heating rate is 1.0 to 2.5° C. / min, and the holding time is 1 to 4 hours.

[0027] Further preferably, the ark in step (4) is a high-temperature resistant corundum or ceramic ark, and the inert gas is argon, nitrogen or a mixture thereof.

[0028] The third technical purpose of the present invention is to provide applications of the above-mentioned 3D conductive network structure heat-conducting and absorbing disk material in the fields of microwave absorption and shielding, thermal management, sensors, supercapacitors, photocatalysis or lithium-ion batteries.

[0029] As can be seen from the above technical solutions, compared with the prior art, the present invention provides a 3D conductive network structure heat-conducting and wave-absorbing disk material and its preparation method and application, which have the following excellent effects:

[0030] 1) The present invention uses alginate as a raw material and metal ion-containing substances such as ferric chloride, nickel chloride, ferric sulfate, nickel sulfate, and cobalt sulfate as crosslinkers. By adopting an ion crosslinking freeze-drying-high-temperature calcination reaction method, a thermally conductive and absorbing disk material with a unique 3D conductive network structure is prepared. The diameter of the disk material ranges from 1501 to 1892 μm. The bowl size and C / Fe atomic ratio are controlled by varying the calcination temperature and the mass fraction of the crosslinker.

[0031] 2) The 3D conductive network structure of the thermally conductive and absorbing disc material disclosed in this invention features a three-dimensional mesh structure and well-developed pores. In the field of electrochemistry, it can provide more active sites for electrochemical reactions, improving capacitance retention. Furthermore, its cross-linking properties can effectively combine with other metal particles, endowing the disc-shaped thermally conductive and absorbing disc material with unique properties, showing great potential in the fields of thermal conductivity, wave absorption, and shielding.

[0032] 3) The preparation method of the thermally conductive and absorbing disc material with a 3D conductive network structure described in the present invention is simple and unique, and the raw materials are cheap and readily available. The reaction process is simple, time-consuming, and energy-efficient. The disc-shaped morphology is retained after freeze-drying and high-temperature calcination, and the stability is good. The product is not used and the product does not generate any environmentally harmful substances. It is green and environmentally friendly, has good reproducibility, low instrument precision requirements, and considerable yield, showing good potential for industrial application.

[0033] Therefore, in summary, the preparation method of the heat-conducting and wave-absorbing disc material with a 3D conductive network structure disclosed and protected by the present invention has great market promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0035] Figures 1 to 5 The physical phase and morphology of the product obtained in Example 1 of the present invention were measured by XRD, EDX, scanning electron microscope and camera respectively.

[0036] Figures 6 to 10 The physical phase and morphology of the product obtained in Example 2 of the present invention were measured under XRD, EDX, scanning electron microscope and camera respectively.

[0037] Figures 11 to 15 The physical phase and morphology of the product obtained in Example 3 of the present invention were measured by XRD, EDX, scanning electron microscope and camera respectively.

[0038] Figures 16 to 19 The phase and morphology of the product obtained in Example 4 of the present invention were measured under XRD, EDX and scanning electron microscope respectively.

[0039] Figures 20 to 23 The phase and morphology of the product obtained in Example 5 of the present invention were measured under XRD, EDX and scanning electron microscope respectively.

[0040] Figures 24 to 28 The phase and morphology of the product obtained in comparative experiment 1 of the present invention were measured under XRD, EDX, scanning electron microscope and camera respectively.

[0041] Figure 29 They are respectively the morphologies of the products obtained in comparative experiment 2 of the present invention measured under a camera.

[0042] Figure 30 They are respectively the morphologies of the products obtained in comparative experiment 3 of the present invention measured under a camera. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] The embodiment of the present invention discloses a heat-conducting and wave-absorbing disk material with a 3D conductive network structure that has simple process, controllable size, and good microwave absorption and shielding properties, as well as a preparation method and application thereof.

[0045] For a better understanding of the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as limiting the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content are also considered to fall within the scope of protection of the present invention.

[0046] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0047] Example 1

[0048] A method for preparing a heat-conducting and wave-absorbing disk material with a 3D conductive network structure specifically comprises the following steps:

[0049] 0.594 g of sodium alginate was dissolved in 50 mL of deionized water and magnetically stirred at room temperature for 4 h to form a sodium alginate solution, which was then hydrolyzed at room temperature to produce Sol A. 19.05 g of the crosslinker FeCl₃·6H₂O and 9.52 g of the surfactant PEG2000 were then weighed and dissolved in 100 mL of deionized water to produce Solution B. Sol A was uniformly injected into Solution B using a single-hole syringe needle to form a disc-shaped gel. The resulting gel was washed with water and ethanol and then frozen solid at –60°C in an ultra-low temperature freezer. The xerogel was then freeze-dried to obtain a xerogel. The xerogel was loaded into an ark and calcined in a tube furnace at 800°C (heating rate of 2.5°C / min) under argon atmosphere for 2 h. The resulting solution was then cooled to room temperature to obtain the C@FeO@Fe₃O₄ bowl.

[0050] The phase, composition, morphology and macroscopic appearance of the obtained products measured by XRD, EDX and SEM are shown in Figures 1 to 5 From the above analysis, we can see that the product is C@FeO@Fe3O4 bowls with an average diameter of 1501μm and a C / Fe atomic ratio of 1.39.

[0051] As shown in Tables 1, 2, and 3, the obtained C@FeO@Fe3O4 bowl has excellent thermal conductivity, wave absorption, and shielding properties. When the filling ratio is 20%, the maximum effective bandwidth of the reflectivity less than or equal to -10 dB is 7.2 GHz, the maximum absorption is -55.13 dB, and the thickness is 3.6 mm. When the filling ratio is 40%, its thermal conductivity, thermal diffusivity, and specific heat are 5.5 W / (m·K), 5.92 mm·s, and 1.3 W / (m·K), respectively. 2 / s and 0.88MJ / m 3 K; When the filling ratio is 50%, the shielding performance is 51.08dB.

[0052] Example 2

[0053] A method for preparing a C@FeO@Fe3O4 thermally conductive and wave-absorbing disc material with a 3D conductive network structure, wherein other conditions remain unchanged, and the masses of the cross-linking agent FeCl3·6H2O and the surfactant PEG2000 are changed to 8.70 g and 4.35 g, respectively, based on Example 1.

[0054] The phase, composition, morphology and macroscopic appearance of the obtained products measured by EDX, XRD and scanning electron microscopy are as follows: Figures 6-10 From the above analysis, we can see that the product is a C@FeO@Fe3O4 bowl with a diameter of 1518μm and a C / Fe atomic ratio of 5.96.

[0055] As shown in Tables 1, 2, and 3, the obtained C@FeO@Fe3O4 bowl has excellent thermal conductivity, wave absorption, and shielding properties. When the filling ratio is 30%, the maximum effective bandwidth of the reflectivity less than or equal to -10 dB is 16.96 GHz, the maximum absorption is -41.16 dB, and the thickness is 2.8 mm. When the filling ratio is 30%, its thermal conductivity, thermal diffusivity, and specific heat are 5.2 W / (m·K), 6.706 mm·s, and 1.3 W / (m·K), respectively. 2 / s and 0.78MJ / m 3 K; When the filling ratio is 50%, the shielding performance is 54.46dB.

[0056] Example 3

[0057] A method for preparing a C@FeO@Fe3O4 thermally conductive and wave-absorbing disc material with a 3D conductive network structure, wherein other conditions remain unchanged, and the masses of the cross-linking agent FeCl3·6H2O and the surfactant PEG2000 are changed to 4.16 g and 2.08 g, respectively, based on Example 1.

[0058] The phase, composition, morphology and macroscopic appearance of the obtained products measured by EDX, XRD and scanning electron microscopy are as follows: Figures 11-15 From the above analysis, we can see that the product is a C@FeO@Fe3O4 bowl with a diameter of 1892μm and a C / Fe atomic ratio of 8.05.

[0059] As shown in Tables 1, 2, and 3, the obtained C@FeO@Fe3O4 bowl has excellent thermal conductivity, wave absorption, and shielding properties. When the filling ratio is 40%, the maximum effective bandwidth of the reflectivity less than or equal to -10dB is 7.44GHz, the maximum absorption is -37.30dB, and the thickness is 3.2mm. When the filling ratio is 30%, its thermal conductivity, thermal diffusivity, and specific heat are 4.37W / (m·K), 5.275mm·s, and 1.30W / (m·K), respectively. 2 / s and 0.83MJ / m 3 K; When the filling ratio is 50%, the shielding performance is 33.73dB.

[0060] Example 4

[0061] A method for preparing a C@Fe3O4 thermally conductive and wave-absorbing disc material with a 3D conductive network structure, wherein other conditions remain unchanged, and the calcination temperature of the tube furnace is changed to 600°C on the basis of Example 1.

[0062] The phase, composition, morphology and macroscopic appearance of the obtained products measured by EDX, XRD and optical electron microscopy are as follows: Figures 16-19 From the above analysis, we can see that the product is a C@Fe3O4 bowl with a diameter of 1561μm and a C / Fe atomic ratio of 7.50.

[0063] As shown in Tables 1, 2, and 3, the obtained C@Fe3O4 bowl has excellent thermal conductivity and wave absorption properties, wherein the maximum effective bandwidth with a reflectivity of less than or equal to -10 dB is 9.92 GHz, the maximum absorption is -41.26 dB, and the thickness is 2.4 mm. When the filling ratio is 30%, its thermal conductivity, thermal diffusivity, and specific heat are 4.18 W / (m·K), 5.321 mm 2 / s and 0.79MJ / m 3 K; When the filling ratio is 50%, the shielding performance is 8.82dB.

[0064] Example 5

[0065] A method for preparing a C@Fe3O4 thermally conductive and wave-absorbing disc material with a 3D conductive network structure, wherein other conditions remain unchanged, and the calcination temperature of the tube furnace is changed to 700°C on the basis of Example 1.

[0066] The phase, composition, morphology and macroscopic appearance of the obtained products measured by EDX, XRD and optical electron microscopy are as follows: Figures 20-23 From the above analysis, we can see that the product is a C@Fe3O4 bowl with a diameter of 1538μm and a C / Fe atomic ratio of 1.61.

[0067] As shown in Tables 1, 2, and 3, the obtained C@Fe3O4 bowl has excellent thermal conductivity. When the filling ratio is 30%, its thermal conductivity, thermal diffusivity, and specific heat are 4.58 W / (m·K), 5.395 mm 2 / s and 0.85MJ / m 3 K; When the filling ratio is 50%, the shielding performance is 17.56dB.

[0068] In order to further verify the excellent effect of the present invention, the inventors also conducted the following experiments:

[0069] Comparative Experiment 1

[0070] A method for preparing a C disc material with a 3D conductive network structure, in which other conditions remain unchanged, the carbon bowl is soaked and washed with 1 mol / L hydrochloric acid, until the disc-shaped gel changes from yellow to white. The phase, composition, and morphology of the obtained product measured by XRD, EDX, and scanning electron microscopy are as follows: Figures 24-28 shown.

[0071] Comparative Experiment 2

[0072] A method for preparing a spherical C material with a 3D conductive network structure, in which other conditions remain unchanged and no surfactant is added based on Example 3, the macroscopic morphology of the obtained product measured under a camera is as follows Figure 29 As shown in Figure 3, it can be seen that only spherical C materials can be obtained without the addition of surfactant. Therefore, surfactant plays a key role in the formation of discs.

[0073] Comparative Experiment 3

[0074] A method for preparing a spherical C material with a 3D conductive network structure, in which other conditions remain unchanged, the crosslinking agent is changed to anhydrous CaCl2 on the basis of Example 3, and the macroscopic morphology of the obtained product measured under a camera is as follows Figure 30 As shown. It can be seen that using anhydrous CaCl2 as a crosslinking agent can only produce spherical C materials. Therefore, Fe 3+ Ions play a key role in the formation of the disk.

[0075] As shown in Tables 1, 2, and 3, the thermal conductivity and shielding properties of the obtained C-containing disc-shaped material are lower than those of the iron-clad sample obtained at the same calcination temperature. The thermal conductivity, thermal diffusivity, and specific heat of the obtained C-containing disc-shaped material are 4.11 W / (m·K), 4.524 mm 2 / s and 0.91MJ / m 3 K; When the filling ratio is 50%, the shielding performance is 19.46dB.

[0076] Table 1 Absorption properties of the products obtained in Examples 1 to 4 of the present invention

[0077]

[0078] Table 2 Thermal conductivity of the products obtained in Examples 1 to 5 of the present invention and Comparative Experiment 1

[0079]

[0080] Table 1 Shielding properties of the products obtained in Examples 1 to 5 of the present invention and Comparative Experiment 1

[0081]

[0082]

[0083] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A heat-conducting and wave-absorbing disk material with a 3D conductive network structure, characterized in that: The thermally conductive wave-absorbing disc material is prepared by an ion cross-linking freeze-drying-calcination process; the thermally conductive wave-absorbing disc material is a composite of mutually cross-linked carbon fibers and magnetic nanoparticles forming a 3D conductive network structure, the magnetic nanoparticles are FeO and Fe3O4, and the diameter of the thermally conductive wave-absorbing disc material is 1501-1892 μm, the carbon fiber content is 48.99-78.02%, and the magnetic nanoparticle content is 21.98-51.01%; The preparation operation of the ion crosslinking freeze drying-calcination process is as follows: The aqueous solution of natural polysaccharide is placed for hydrolysis, and then the sol is evenly injected into a mixed solution of a cross-linking agent and a surfactant to form a disc-shaped material. After freeze-drying and calcination, the cross-linking agent is carbon thermally reduced to generate magnetic particles, and the natural polysaccharide is decomposed into carbon fibers, which are then wrapped around the magnetic particles to obtain the thermally conductive and wave-absorbing disc material with the 3D conductive network structure.

2. A method for preparing the heat-conducting and wave-absorbing disk material with a 3D conductive network structure as claimed in claim 1, characterized in that: The method specifically comprises the following steps: (1) Stir the natural polysaccharide aqueous solution and then allow it to hydrolyze into sol A; (2) Weigh the crosslinker and surfactant and dissolve them in deionized water. Stir to form a crosslinker solution B. Use a syringe pump to evenly inject sol A into the crosslinker solution B to form a disc material. (3) soaking the disc material in water and ethanol, washing it, and then freeze-drying it to obtain a xerogel; (4) calcining the dry gel and keeping it warm to obtain the heat-conducting and wave-absorbing disc material; The cross-linking agent is at least one of soluble ferric chloride, nickel chloride, ferric sulfate, nickel sulfate, and cobalt sulfate, the mass fraction of the cross-linking agent in water is 4% to 16%, and the mass ratio of the cross-linking agent to the surfactant is 2:1; The calcination temperature in step (4) is 600°C to 800°C, the calcination time is 2 to 4 h, the heating rate is 1.0 to 2.5°C / min, and the holding time is 1 to 4 h.

3. The method for preparing a heat-conducting and wave-absorbing disk material with a 3D conductive network structure according to claim 2, characterized in that: The natural polysaccharide is sodium alginate or potassium alginate, and the concentration is 0.04-0.08 mol / L.

4. The method for preparing a heat-conducting and wave-absorbing disk material with a 3D conductive network structure according to claim 2, characterized in that: The surfactant is polyethylene glycol PEG 400-20000, and the concentration of the surfactant is 0.0416-0.381 mol / L.

5. The method for preparing a heat-conducting and wave-absorbing disk material with a 3D conductive network structure according to claim 2, characterized in that: The soaking time in step (3) is 1 h, the freeze-drying temperature is -30°C to -60°C, and the freeze-drying time is 20 to 40 h.

6. Use of the thermally conductive absorbing disc material having a 3D conductive network structure as claimed in claim 1 or the thermally conductive absorbing disc material having a 3D conductive network structure prepared by the method according to any one of claims 2 to 5 in microwave absorption and shielding, thermal management, sensors, supercapacitors, photocatalysis, or lithium-ion batteries.

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