Heat insulation-heat conduction integrated phase change composite material and preparation method thereof

Abstract

The invention relates to the technical field of phase change energy storage and heat management, and provides a heat insulation-heat conduction integrated phase change composite material and a preparation method thereof. The preparation method comprises the following steps: S1, preparing heat-conducting layer precursor mixed slurry; s2, preparing a heat insulation layer precursor mixed solution; s3, respectively pouring the two solutions into customized molds, directionally freezing and freeze-drying; s4, carrying out thermal imidization; and S5, partially impregnating the phase-change material, and packaging the phase-change material in a skeleton of the heat-conducting layer aerogel by adopting a physical adsorption method. The calcium ion regulator is introduced into the heat insulation layer precursor solution, so that the pore diameter structure of the polyimide aerogel can be regulated and controlled, and the calcium ion regulator can be used as a bridge to connect the heat insulation layer and the heat conduction layer, so that the integrated design of the material is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change energy storage and thermal management, and in particular to a heat insulation-heat conduction integrated phase change composite material and a preparation method thereof. Background Art

[0002] Phase change latent heat storage technology has shown great application potential in the fields of building energy conservation and solar energy utilization due to its efficient latent heat storage capacity. This technology achieves energy storage and release through the release or absorption of latent heat during the phase change of materials. In order to improve the thermal conductivity of the system, researchers designed a directional heat conduction structure to enhance the thermal conductivity by optimizing the heat flow path. However, although this design improves the thermal conductivity in the short term, it also speeds up the transfer of heat, resulting in the rapid release of stored heat, which is contrary to the demand for continuous heating in the building field and the need for electronic components to resist transient heat pulses.

[0003] In order to resolve this contradiction, a composite structure design between a high thermal conductivity phase change layer and a low thermal conductivity aerogel layer was proposed. This design aims to quickly absorb and release heat through the high thermal conductivity phase change material, while using the low thermal conductivity aerogel layer to slow down heat loss, so as to achieve long-term heat retention. However, this composite material has the problem of insufficient interface connection strength in practical applications. This causes the material to crack during use, affecting the stability and service life of the material. Therefore, how to achieve the integration of the high thermal conductivity phase change layer and the low thermal conductivity aerogel layer structure has become a key technical problem in improving the performance of the phase change latent heat storage system. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a thermal insulation-thermal conduction integrated phase change composite material and a preparation method thereof, thereby solving the problem in the prior art of lacking an integrated special material having thermal conduction, heat storage and thermal insulation functions.

[0005] The present invention adopts the following technical solution:

[0006] In one aspect, the present invention provides a method for preparing a thermal insulation-thermal conductivity integrated phase change composite material, comprising:

[0007] S1, dissolving a thickener and a thermally conductive filler in a cellulose aqueous solution to obtain a thermally conductive layer precursor mixed slurry;

[0008] S2, dissolving the thermal insulation layer polymer, nanofibers, inorganic nanofillers and calcium ion regulator in water and mixing them evenly to obtain a thermal insulation layer precursor mixed solution;

[0009] S3, pouring the thermal conductive layer precursor mixed slurry and the thermal insulation layer precursor mixed liquid into a customized mold, directionally freezing with liquid nitrogen, and freeze-drying to obtain an aerosol;

[0010] S4, subjecting the freeze-dried aerosol to thermal imidization;

[0011] S5. Immerse the heat-conducting layer of the product after thermal imidization into the molten phase change material, partially immerse the phase change material, and use physical adsorption method to encapsulate the phase change material in the skeleton of the heat-conducting layer aerogel to obtain the thermal insulation-heat conduction integrated phase change composite material.

[0012] Any possible implementation as described above further provides an implementation, in which in step S1, the concentration of the cellulose aqueous solution is 1-10 mg / mL, and the mass ratio of the added amount of the thickener to the thermal conductive filler is 200:(50-1000).

[0013] The above parameter range is the optimal range that balances the thermal conductivity of the thermal conductive layer and the viscosity of the precursor solution; when the parameter is lower than the lower limit, the amount of thermal conductive filler added is insufficient, resulting in an insignificant increase in the thermal conductivity of the thermal conductive layer, which cannot meet the requirements of efficient storage and release of thermal energy during the application process; when the parameter is higher than the upper limit, the viscosity of the precursor solution is significantly reduced, which cannot meet the requirements of the thermal insulation layer solution floating on the upper part of the thermal conductive layer solution before the directional freezing process and cannot be separated into layers.

[0014] Any possible implementation as described above, further provides an implementation, in step S2, the mass ratio of the added amount of the thermal insulation layer polymer and the nanofiber is 600: (10~200), the mass ratio of the added amount of the thermal insulation layer polymer and the nanofiller is: 600: (10~200), the concentration of the calcium ion regulator is 0.1 mol / L, and the added amount is 0.2~5 mL.

[0015] The above parameter range is the optimal range that balances the shrinkage resistance and thermal conductivity of the thermal insulation layer aerogel; when the mass ratio of the thermal insulation layer polymer and nanofiber / nanofiller addition is lower than the lower limit, the amount of nanofiller and nanofiber added is insufficient, resulting in severe skeleton shrinkage of the polyimide acid aerogel during freeze drying and thermal imidization, significantly reducing the thermal insulation performance of the aerogel. When the parameter is higher than the upper limit, the amount of nanofiller added is too much, resulting in a significant increase in the thermal conductivity of the polyimide aerogel, reducing the thermal insulation performance of the aerogel.

[0016] Any possible implementation as described above, further provides an implementation, in step S3, first pouring the thermal conductive layer precursor mixed slurry into a customized mold, and then slowly pouring the thermal insulation layer precursor mixed liquid into the upper part of the thermal conductive layer precursor mixed slurry, after standing for a certain period of time, directionally freezing with liquid nitrogen.

[0017] Any possible implementation described above further provides an implementation, in step S4, the conditions for the thermal imidization are: in a nitrogen atmosphere, keep warm at 200°C for 1 to 2 hours, keep warm at 300°C for 1 to 4 hours, and the heating rate is 3 to 6°C.

[0018] / min.

[0019] Any possible implementation as described above further provides an implementation, in step S5, the mass and adsorption time of the molten phase change material are regulated to ensure that the thermal conductive layer is fully impregnated with the phase change material, while the thermal insulation layer has zero adsorption of the phase change material.

[0020] Any possible implementation as described above, further provides an implementation, in step S1, the thickener is sodium alginate, and the thermal conductive filler is any one of single-walled carbon nanotubes, carbon fibers, graphene nanosheets, graphene oxide (GO), reduced graphene oxide, MXene, expanded graphite, aluminum nitride, and boron nitride.

[0021] Any possible implementation as described above, further provides an implementation, in step S2, the thermal insulation layer polymer is polyimide acid (PAA), the nanofiber is any one of aramid nanofiber, carboxymethyl cellulose, cellulose nanofiber, microcrystalline cellulose, cellulose nanocrystals, cellulose nanonet, the inorganic nanofiller is any one of nano silicon dioxide, graphene oxide, carbon nanotube, nano clay, nano alumina, nano aluminum hydroxide, nano zirconium oxide, nano zinc borate, nano titanium dioxide and nano silicate, and the calcium ion regulator is any one of calcium fluoride, calcium chloride, calcium bromide, calcium nitrate and calcium acetate. Aqueous solution.

[0022] In step S4, the purpose of thermal imidization is to dehydrate PAA into a ring to form an imidized structure, and convert it into a polyimide (PI) aerogel with higher thermal stability and thermal insulation performance; the thermal imidization process can not only enhance the rigidity of the molecular chain, but also eliminate the residual solvent small molecules in the chain segment.

[0023] Any possible implementation as described above further provides an implementation, in step S5, the calcium ion regulator is any aqueous solution of calcium fluoride, calcium chloride, calcium bromide, calcium nitrate, and calcium acetate.

[0024] On the other hand, the present invention also provides a thermal insulation-heat conduction integrated phase change composite material, and the composite material is obtained by the above-mentioned preparation method.

[0025] The beneficial effects of the present invention are:

[0026] 1. The preparation method of the phase change composite material of the present invention is designed for aerogel insulation layer materials, and uses horizontal directional freezing technology and the addition of calcium ions for structural regulation to achieve skeleton orientation in the horizontal direction and improve the thermal insulation performance of the material in the vertical direction; for the design of the phase change thermal conductive layer material, by adding thermal conductive fillers, a vertical thermal conductive channel is constructed by directional freezing in the vertical direction to improve its thermal conductivity. Finally, a thermal insulation-heat storage integrated phase change composite material with excellent thermal conductivity, heat storage and thermal insulation is obtained.

[0027] 2. The phase change composite material made by the present invention has the advantages of high heat storage density, high thermal stability, and long temperature control time. The heat insulation layer and the heat conductive layer are designed with orthogonal orientation to achieve rapid heat storage while delaying heat transfer. The phase change composite material can quickly absorb / release thermal energy on the surface of the thermal management object and isolate heat transfer to a large extent. For the field of building energy-saving temperature control or the field of thermal management of electronic components, it can achieve instantaneous storage and hoarding of heat, improving the continuity and safety reliability of the thermal management process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 : Front view (a) and top view (b) of the custom freezing mold in an embodiment of the present invention.

[0029] Figure 2 : Scanning electron microscope images of the thermal insulation-conductivity integrated aerogel thermal conductive layer (a), thermal insulation layer (b) and the interface between the two layers (c) obtained in Example 1.

[0030] Figure 3 : Scanning electron microscope images of the thermal insulation-conductivity integrated aerogel thermal conductive layer (a), thermal insulation layer (b) and the interface between the two layers (c) obtained in Example 2.

[0031] Figure 4 : Scanning electron microscope images of the phase change layers obtained in Example 1 (a) and Example 2 (b).

[0032] Figure 5 : Example 1 Melting and solidification curves and enthalpy values ​​of materials at the bottom of the phase change layer, the middle of the phase change layer, the interface and the middle of the thermal insulation layer.

[0033] Figure 6 : Example 1 Melting and solidification curves and enthalpy values ​​of materials at the bottom of the phase change layer, the middle of the phase change layer, the interface and the middle of the thermal insulation layer.

[0034] Figure 7 Shown is a schematic flow chart of a method for preparing a thermal insulation-thermal conduction integrated phase change composite material according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The specific embodiments of the present invention will be described in detail below in conjunction with specific drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects.

[0036] A method for preparing a heat-insulating and heat-conducting integrated phase-change composite material according to an embodiment of the present invention comprises:

[0037] S1, dissolving a thickener and a thermally conductive filler in a cellulose aqueous solution to obtain a thermally conductive layer precursor mixed slurry;

[0038] S2, dissolving the thermal insulation layer polymer, nanofibers, inorganic nanofillers and calcium ion regulator in water and mixing them evenly to obtain a thermal insulation layer precursor mixed solution;

[0039] S3, pouring the thermal conductive layer precursor mixed slurry and the thermal insulation layer precursor mixed liquid into a customized mold, directionally freezing with liquid nitrogen, and freeze-drying to obtain an aerosol;

[0040] S4, subjecting the freeze-dried aerosol to thermal imidization;

[0041] S5. Immerse the heat-conducting layer of the product after thermal imidization into the molten phase change material, partially immerse the phase change material, and use physical adsorption method to encapsulate the phase change material in the skeleton of the heat-conducting layer aerogel to obtain the thermal insulation-heat conduction integrated phase change composite material.

[0042] The specific process is as follows Figure 7 shown.

[0043] In a specific embodiment, in step S1, the concentration of the cellulose aqueous solution is 1-10 mg / mL, and the ratio of the thickener to the thermal conductive filler is 200:(50-1000).

[0044] In a specific embodiment, in step S2, the mass ratio of the addition amount of the thermal insulation layer polymer and the nanofiber is 600:

[0045] (10-200), the mass ratio of the added amount of the thermal insulation layer polymer and the nanofiller is: 600:(10-200), the concentration of the calcium ion regulator is 0.1 mol / L, and the added amount is 0.2-5 mL.

[0046] In a specific embodiment, in step S3, the thermal conductive layer precursor mixed slurry is first poured into a customized mold, and then the thermal insulation layer precursor mixed liquid is slowly poured into the upper part of the thermal conductive layer precursor mixed slurry, and after standing for a certain period of time, liquid nitrogen is used for directionally freezing.

[0047] In a specific embodiment, in step S4, the conditions for thermal imidization are: in a nitrogen atmosphere, keep warm at 200° C. for 1 to 2 hours, keep warm at 300° C. for 1 to 4 hours, and the heating rate is 3 to 6° C. / min.

[0048] In a specific embodiment, in step S5, the mass and adsorption time of the molten phase change material are regulated to ensure that the heat conductive layer is fully impregnated with the phase change material, while the heat insulating layer has zero adsorption of the phase change material.

[0049] In a specific embodiment, in step S1, the thickener is sodium alginate, and the thermal conductive filler is any one of single-walled carbon nanotubes, carbon fibers, graphene nanosheets, graphene oxide (GO), reduced graphene oxide, MXene, expanded graphite, aluminum nitride, and boron nitride.

[0050] In a specific embodiment, in step S2, the thermal insulation layer polymer is polyimide acid (PAA), the nanofiber is any one of aramid nanofiber, carboxymethyl cellulose, cellulose nanofiber, microcrystalline cellulose, cellulose nanocrystal, and cellulose nanomesh, the inorganic nanofiller is any one of nano-silicon dioxide, graphene oxide, carbon nanotube, nano-clay, nano-aluminum oxide, nano-aluminum hydroxide, nano-zirconium oxide, nano-zirconia, nano-zinc borate, nano-titanium dioxide, and nano-silicate, and the calcium ion regulator is any one of calcium fluoride, calcium chloride, calcium bromide, calcium nitrate, and calcium acetate. Aqueous solution.

[0051] In a specific embodiment, in step S5, the calcium ion regulator is any one aqueous solution of calcium fluoride, calcium chloride, calcium bromide, calcium nitrate, and calcium acetate.

[0052] The present invention provides a thermal insulation-heat conduction integrated phase change composite material, and the composite material is obtained by the above-mentioned preparation method.

[0053] Unless otherwise specified, the reagents used in the following examples were purchased from commercial sources without additional purification.

[0054] Preparation of PAA: Weigh 4.95 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve it in 90 mL of N,N-dimethylacetamide (DMAc), then add 5.48 g of pyromellitic dianhydride (PMDA) and stir in an ice-water bath for 3 h at a speed of 600 rpm to obtain a linear PAA solution, wash with acetone, and remove excess solvent after drying to obtain solid PAA.

[0055] Example 1

[0056] 1) Weigh 0.6 g PAA and dissolve it in 14 mL water, then add 0.4 mL triethylamine and stir vigorously to obtain a clear PAA solution; weigh 0.2 g sodium alginate and 0.1 g GO and add them to 25 ml 2 mg / mL cellulose nanofiber aqueous solution, stir thoroughly until uniform to obtain thermal conductive layer precursor solution A;

[0057] 2) 10 mL of 2 mg / mL cellulose nanofiber aqueous solution was added to the PAA solution, stirred for 3 h, and then 1 mL of 0.1 mol / L calcium chloride aqueous solution was added, stirred for 0.5 h, to obtain a thermal insulation layer precursor solution B;

[0058] 3) Solution A was poured into a custom mold, and solution B was slowly poured onto the top of solution A, and liquid nitrogen was used for directionally freezing, followed by freeze drying for 72 hours to obtain the thermal insulation and thermal conductivity integrated aerogel (PAA-GO);

[0059] 4) The aerogel was placed in a nitrogen atmosphere and kept at 200°C for 1 hour and 300°C for 2 hours at a heating rate of 5°C / min. PAA was thermally imidized to obtain polyimide (PI);

[0060] 5) Weigh 5g of polyethylene glycol 6000 and 10g of ethanol and mix them to melt. Place the PI-based thermal insulation and thermal conductivity integrated aerogel in the melted phase change material and let it stand for 10 minutes to allow the thermal conductive phase change layer to fully absorb the phase change core material. Wipe off the excess phase change material with filter paper to obtain the thermal insulation and thermal conductivity integrated phase change composite material PI-GO / PEG.

[0061] Figure 1 The mold is customized. The bottom of the mold is made of brass block, the lower part is made of polytetrafluoroethylene, and the upper part is made of brass block and polytetrafluoroethylene. Before formal freezing, the upper brass block is placed in liquid nitrogen for pre-cooling. Then the thermal conductive layer and thermal insulation layer precursor solutions are poured into the mold respectively and frozen with liquid nitrogen. Since the thermal conductivity of the brass block is significantly greater than that of polytetrafluoroethylene, the ice crystals in the precursor solution first nucleate on the three brass blocks and grow along the temperature gradient. Specifically, the ice crystals of the thermal conductive layer grow in the vertical direction, while the ice crystals of the thermal insulation layer grow in the horizontal direction. The arrangement of the oriented structure is achieved during the freezing process. Finally, after freeze-drying, the ice crystals sublimate, leaving an oriented thermal conductive / insulating frame.

[0062] Figure 2 The scanning electron microscope images of various regions of the phase change composite material carrier PI-GO aerogel in this embodiment show that the thermal conductive layer presents a vertically arranged structure, the thermal insulating layer presents a horizontally arranged structure, and two mutually perpendicularly oriented structures are observed at the interface between the thermal insulating layer and the thermal conductive layer.

[0063] Figure 4(a) is a scanning electron micrograph of the phase change layer of the PI-GO / PEG phase change composite material in this embodiment, in which the phase change material is fully loaded in the skeleton.

[0064] Figure 5 The melting and solidification curves of the PI-GO / PEG phase change composite material in various regions of this embodiment show that in the phase change layer, the phase change enthalpy value shows a gradually decreasing trend with increasing height, while in the thermal insulation layer, there is almost no phase change material.

[0065] Example 2

[0066] 1) Weigh 0.6 g PAA and dissolve it in 14 mL water, then add 0.4 mL triethylamine and stir vigorously to obtain a clear PAA solution; weigh 0.2 g sodium alginate and 0.1 g GO and add them to 25 ml 2 mg / mL aramid nanofiber aqueous solution, stir thoroughly until uniform to obtain thermal conductive layer precursor solution A;

[0067] 2) 10 mL of 2 mg / mL aramid nanofiber aqueous solution was added to the PAA solution, stirred for 3 h, and then 1 mL of 0.1 mol / L calcium chloride aqueous solution was added, stirred for 0.5 h, to obtain a thermal insulation layer precursor solution B;

[0068] 3) Solution A was poured into a custom mold, and solution B was slowly poured onto the top of solution A, and liquid nitrogen was used for directionally freezing, followed by freeze drying for 72 hours to obtain the thermal insulation and thermal conductivity integrated aerogel (PAA-GO);

[0069] 4) The aerogel was placed in a nitrogen atmosphere and kept at 200°C for 1 hour and 300°C for 2 hours at a heating rate of 5°C / min. PAA was thermally imidized to obtain polyimide (PI);

[0070] 5) Weigh 5g of polyethylene glycol 6000 and 10g of ethanol and mix them to melt. Place the PI-based thermal insulation and thermal conductivity integrated aerogel in the melted phase change material and let it stand for 10 minutes to allow the thermal conductive phase change layer to fully absorb the phase change core material. Wipe off the excess phase change material with filter paper to obtain the thermal insulation and thermal conductivity integrated phase change composite material PI-GO / PEG.

[0071] Figure 3 The scanning electron microscope images of various regions of the phase change composite material carrier PI-GO aerogel in this embodiment show that the thermal conductive layer presents a vertically arranged structure, the thermal insulating layer presents a horizontally arranged structure, and two mutually perpendicularly oriented structures are observed at the interface between the thermal insulating layer and the thermal conductive layer.

[0072] Figure 4 (b) is a scanning electron micrograph of the phase change layer of the PI-GO / PEG phase change composite material in this embodiment, in which the phase change material is fully loaded in the skeleton.

[0073] Figure 6 The melting and solidification curves of the PI-GO / PEG phase change composite material in various regions of this embodiment show that in the phase change layer, the phase change enthalpy value shows a gradually decreasing trend with increasing height, while in the thermal insulation layer, there is almost no phase change material.

[0074] The thermal insulation-heat conduction integrated phase change composite material provided by the present invention has excellent mechanical and functional stability, and excellent thermal insulation, thermal conduction and heat storage properties.

[0075] The present invention uses calcium ions to affect the structure by means of charge interaction with the polyimide acid chain segment. The polyimide acid chain segment contains a large amount of carboxylate (-COO - ), calcium ions tend to react with -COO - Charge interaction occurs, and the calcium ion exhibits a positively charged divalent state, which can connect the two -COO - The polyimide acid segments make the connection between polymer segments more compact, and the structure shows smaller pore size and higher specific surface area, which can reduce the thermal conductivity of the thermal insulation layer. Similarly, the main component of the thermal conductive layer precursor solution is sodium alginate, which also contains a large amount of carboxylate -COO - Calcium ions can act as a bridge to simultaneously connect the polymer segments in the thermal insulation layer and the sodium alginate that forms the framework of the thermal conductive layer, ultimately achieving the integrated preparation of the thermal insulation layer and the thermal conductive layer skeleton. If calcium ions are not used, there is no strong interaction force between the thermal insulation layer and the thermal conductive layer, and the double-layer structure is prone to separation during application.

[0076] The polyimide aerogel used in the present invention is cross-linked with the doped calcium ions, thus having a rich and adjustable porous structure, and the microscopic horizontal orientation of the polyimide aerogel is achieved through the orientation effect, which is orthogonal to the heat transfer direction and blocks heat exchange. The polyimide aerogel has good flame retardancy, and its mechanical properties are enhanced through structural adjustment, showing good thermal insulation and thermal stability.

[0077] The phase change composite material provided by the present invention has a high degree of integration, the gelation of sodium alginate and calcium ions enhances the stability of the heat-conducting layer, and the vertically oriented heat-conducting layer and the horizontally oriented heat-insulating layer are cross-linked by calcium ions to achieve interface connection.

[0078] Although several embodiments of the present invention have been given herein, those skilled in the art should understand that the embodiments of the present invention may be modified without departing from the spirit of the present invention. The above embodiments are merely exemplary and should not be used as a limitation on the scope of the present invention.

Claims

1. A method for preparing a heat-insulating and heat-conducting integrated phase-change composite material, characterized in that: The preparation method comprises: S1, dissolving a thickener and a thermally conductive filler in a cellulose aqueous solution to obtain a thermally conductive layer precursor mixed slurry; S2, dissolving the thermal insulation layer polymer, nanofibers, inorganic nanofillers and calcium ion regulator in water and mixing them evenly to obtain a thermal insulation layer precursor mixed solution; S3, pouring the thermal conductive layer precursor mixed slurry and the thermal insulation layer precursor mixed liquid into a customized mold, directionally freezing with liquid nitrogen, and freeze-drying to obtain an aerosol; S4, subjecting the freeze-dried aerosol to thermal imidization; S5. Immerse the heat-conducting layer of the product after thermal imidization into the molten phase change material, partially immerse the phase change material, and use physical adsorption method to encapsulate the phase change material in the skeleton of the heat-conducting layer aerogel to obtain the thermal insulation-heat conduction integrated phase change composite material.

2. The method for preparing the thermal insulation-thermal conduction integrated phase change composite material according to claim 1, characterized in that: In step S1, the concentration of the cellulose aqueous solution is 1-10 mg / mL, and the mass ratio of the added amount of the thickener to the thermal conductive filler is 200: (50～1000)。 3. The method for preparing the thermal insulation-thermal conduction integrated phase change composite material according to claim 1, characterized in that: In step S2, the mass ratio of the added amount of the thermal insulation layer polymer and the nanofiber is 600:(10-200), the mass ratio of the added amount of the thermal insulation layer polymer and the nanofiller is 600:(10-200), the concentration of the calcium ion regulator is 0.1 mol / L, and the added amount is 0.2-5 mL.

4. The method for preparing the thermal insulation-heat conduction integrated phase change composite material according to claim 1, characterized in that: In step S3, the thermal conductive layer precursor mixed slurry is first poured into a customized mold, and then the thermal insulation layer precursor mixed liquid is slowly poured into the upper part of the thermal conductive layer precursor mixed slurry, and after standing for a certain period of time, it is directionally frozen with liquid nitrogen.

5. The method for preparing the thermal insulation-thermal conduction integrated phase change composite material according to claim 1, characterized in that: In step S4, the conditions for the thermal imidization are: in a nitrogen atmosphere, keep warm at 200° C. for 1 to 2 hours, keep warm at 300° C. for 1 to 4 hours, and the heating rate is 3 to 6° C. / min.

6. The method for preparing the thermal insulation-heat conduction integrated phase change composite material according to claim 1, characterized in that: In step S5, the mass and adsorption time of the molten phase change material are adjusted to ensure that the heat conductive layer is fully impregnated with the phase change material and the heat insulating layer has zero adsorption of the phase change material.

7. The method for preparing the thermal insulation-heat conduction integrated phase change composite material according to claim 1, characterized in that: In step S1, the thickener is sodium alginate, and the thermal conductive filler is any one of single-walled carbon nanotubes, carbon fibers, graphene nanosheets, graphene oxide, reduced graphene oxide, MXene, expanded graphite, aluminum nitride, and boron nitride.

8. The method for preparing the thermal insulation-heat conduction integrated phase change composite material according to claim 1, characterized in that: In step S2, the thermal insulation layer polymer is polyimide acid, the nanofiber is any one of aramid nanofiber, carboxymethyl cellulose, cellulose nanofiber, microcrystalline cellulose, cellulose nanocrystal, and cellulose nanomesh, the inorganic nanofiller is any one of nano-silicon dioxide, graphene oxide, carbon nanotubes, nano-clay, nano-aluminum oxide, nano-aluminum hydroxide, nano-zirconium oxide, nano-zirconia, nano-zirconia, nano-titanium dioxide, and nano-silicate, and the calcium ion regulator is any one of calcium fluoride, calcium chloride, calcium bromide, calcium nitrate, and calcium acetate. Aqueous solution.

9. The method for preparing the thermal insulation-heat conduction integrated phase change composite material according to claim 1, characterized in that: In step S5, the calcium ion regulator is any one aqueous solution of calcium fluoride, calcium chloride, calcium bromide, calcium nitrate, and calcium acetate.

10. A thermal insulation-thermal conduction integrated phase change composite material, characterized in that: The composite material is obtained by the preparation method according to any one of claims 1 to 9.

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