Inorganic salt / carbon aerogel composite phase change material and preparation method thereof

Abstract

The invention provides an inorganic salt / carbon aerogel composite phase change material and a preparation method thereof, and belongs to the technical field of phase change material preparation. The composite phase change material is prepared through electrochemical stripping, HF etching, freeze drying, high-temperature carbonization and vacuum impregnation. The electrochemical exfoliated graphene and the TiC / carbon aerogel are combined together through self-assembly to construct a heterogeneous interface and increase effective nucleation sites, so that the energy potential barrier of phonon scattering and nucleation is reduced, and the thermal conductivity is improved while the degree of supercooling is reduced; the aerogel adsorbing the inorganic salt phase change material forms hydrogel with a compact network through self-assembly, crystallization of the hydrated salt is promoted, and the hydrated salt inorganic phase change material is limited in a porous material by utilizing the confinement effect of a nano material, so that the hydrated salt inorganic phase change material is not easy to leak, and relatively good latent heat is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change material preparation, and in particular to an inorganic salt / carbon aerogel composite phase change material and a preparation method thereof. Background Art

[0002] As the global energy structure transitions toward a low-carbon one, the development of efficient and low-cost energy storage technologies has become key to achieving large-scale utilization of renewable energy. Phase change materials, with their excellent latent heat properties, can store and controllably release thermal energy through physical transitions within a specific temperature range, and are considered one of the most promising heat storage media. However, traditional phase change materials face two core bottlenecks in practical applications: first, their inherent thermal conductivity is generally low, resulting in slow heat storage and release rates, which severely restricts their power density; second, material leakage caused by volume changes during the phase change process not only reduces cycle stability but can also pollute equipment and the environment.

[0003] At present, the mainstream solution to the above problems focuses on composite material modification. For example, although low-temperature phase change material systems can achieve high heat storage density and low cost through inorganic salt-water or organic-water mixed designs, the severe supercooling phenomenon (supercooling can reach more than 10°C) caused by insufficient nucleation sites during the solidification process significantly weakens the practical application efficiency. In recent years, researchers have tried to solve the leakage problem by constructing three-dimensional porous skeletons (such as carbon aerogels and metal foams) to encapsulate phase change materials, and use the high thermal conductivity of the skeleton to improve the overall thermal conductivity. However, the existing technology still has obvious limitations: on the one hand, the interface compatibility between traditional porous skeletons and phase change matrices is poor, which easily leads to composition segregation; on the other hand, single-dimensional structural design makes it difficult to simultaneously achieve nucleation control, phonon transmission optimization and mechanical stability improvement. In particular, for hydrated salt phase change systems, how to control crystallization behavior at the nanoscale to suppress supercooling while maintaining the stability of the high thermal conductivity network remains a technical difficulty that needs to be overcome.

[0004] Recent research indicates that two-dimensional nanomaterials (such as MXene and hexagonal boron nitride) are ideal functional fillers due to their ultrahigh intrinsic thermal conductivity (>100 W / (m·K)) and abundant surface functional groups. Heterostructured with a three-dimensional porous framework, these materials can achieve multiple synergistic effects: First, the interlayer confinement of the two-dimensional filler significantly increases the nucleation site density of the phase change matrix, reducing the supercooling to less than 2°C. Second, the continuous thermal conductivity of the three-dimensional framework combined with the in-plane phonon transport properties of the two-dimensional filler enhances the thermal conductivity of the composite. Furthermore, the chemically bonded interface between the framework and the filler effectively blocks liquid phase leakage and improves the thermal cycling stability of the material. Despite this, existing methods still suffer from limitations in heterojunction interface design, pore structure gradient control, and scalable fabrication processes, resulting in limited performance improvements. Therefore, developing an inorganic salt / carbon aerogel composite phase change material and its preparation method, which utilizes the confinement of nanomaterials to confine a hydrated salt inorganic phase change material within a porous matrix, is of great significance. Summary of the Invention

[0005] The object of the present invention is to provide an inorganic salt / carbon aerogel composite phase change material and a preparation method thereof, so as to solve the problem of relatively poor performance of composite phase change materials in the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing an inorganic salt / carbon aerogel composite phase change material, comprising the following steps:

[0008] (1) lithium fluoride, hydrochloric acid solution and Ti3AlC2 powder are mixed and reacted, washed, ultrasonically treated and centrifuged to obtain a MXene dispersion;

[0009] (2) mixing the MXene dispersion, sodium hydroxide, urea, and water and precooling the mixture to obtain a mixed dispersion;

[0010] (3) Cellulose and N,N-methylenebisacrylamide were added to the mixed dispersion for gelation, standing, washing and freeze-drying to obtain Ti3C2T x / cellulose aerogel;

[0011] (4) Ti3C2T x / cellulose aerogel is pre-sintered and sintered to obtain TiC / carbon aerogel;

[0012] (5) immersing the TiC / carbon aerogel in an inorganic salt aqueous solution to obtain an inorganic salt / carbon aerogel composite phase change material;

[0013] The inorganic salt aqueous solution is mainly prepared by mixing graphene, Na2HPO4·12H2O and NH4Cl.

[0014] Preferably, in step (1), the mass volume ratio of the lithium fluoride and the hydrochloric acid solution is 2g:30~50mL; the concentration of the hydrochloric acid solution is 8~10mol / L; the mass volume ratio of the Ti3AlC2 powder and the hydrochloric acid solution is 2g:30~50mL.

[0015] Preferably, in step (1), the reaction temperature is 30-40°C, and the reaction time is 22-26 hours; the frequency of the ultrasonic treatment is 300-400W, and the time is 10-20 minutes; the speed of the centrifugal treatment is 3000-4000 rpm, and the time is 2-7 minutes.

[0016] Preferably, in step (2), the mass ratio of MXene, sodium hydroxide, urea and water in the MXene dispersion is 0.02-0.3:7:12:81.

[0017] Preferably, the mass ratio of the Ti3AlC2 powder to the cellulose is 2:2-3.

[0018] Preferably, in step (3), the molar ratio of cellulose to N,N-methylenebisacrylamide is 1:1; ultrasonic treatment is performed during the gelation process, and the ultrasonic treatment time is 0.5 to 1.5 hours; and the static treatment time is 24 to 48 hours.

[0019] Preferably, in step (4), the heating rate during the pre-sintering is 1-3°C / min, the temperature is 200-400°C, and the time is 0.5-1.5h; the heating rate during the sintering is 4-6°C / min, the temperature is 1100-1300°C, and the time is 1-3h.

[0020] Preferably, in the inorganic salt aqueous solution, the concentration of Na2HPO4·12H2O is 2-5%, the concentration of NH4Cl is 0.5-3%, and the concentration of graphene is 0.5-2%.

[0021] Preferably, in step (5), the impregnation is vacuum impregnation, the impregnation time is 4 to 6 minutes, and the vacuum degree is 0.1 Pa.

[0022] The present invention also provides an inorganic salt / carbon aerogel composite phase change material prepared by the above-mentioned method for preparing the inorganic salt / carbon aerogel composite phase change material.

[0023] Beneficial effects of the present invention:

[0024] The present invention uses electrochemically exfoliated graphene as a two-dimensional thermally conductive filler and TiC / carbon aerogel as a three-dimensional porous material, which are combined together through self-assembly to construct a heterogeneous interface and increase effective nucleation sites, thereby reducing the energy barrier of phonon scattering and nucleation, thereby reducing supercooling while improving thermal conductivity. Moreover, the aerogel adsorbed with inorganic salt phase change material forms a dense network hydrogel through self-assembly, promoting the crystallization of hydrated salts, and utilizing the confinement effect of nanomaterials to confine the hydrated salt inorganic phase change material within the porous material, making it less likely to leak and maintaining a good latent heat.

[0025] The inorganic salt / carbon aerogel composite phase change material prepared by the present invention is a composite phase change material based on a two-dimensional / three-dimensional multi-level heterogeneous interface. Through self-assembly technology, it is combined with two-dimensional graphene nanosheets on the surface of three-dimensional TiC / carbon aerogel to construct a multifunctional skeleton with multi-level pores and chemically cross-linked interfaces. This solves the bottleneck of the mutual restriction of "high thermal conductivity" and "anti-leakage" performance in traditional composite phase change materials, and provides new ideas and methods for the development of high-performance phase change materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the SEM image of the graphene prepared in Example 1;

[0027] Figure 2 This is the DSC graph of the inorganic salt phase change material prepared in Example 1;

[0028] Figure 3 This is the DSC graph of the inorganic salt / carbon aerogel composite phase change material prepared in Example 1. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing an inorganic salt / carbon aerogel composite phase change material, comprising the following steps:

[0030] (1) lithium fluoride, hydrochloric acid solution and Ti3AlC2 powder are mixed and reacted, washed, ultrasonically treated and centrifuged to obtain a MXene dispersion;

[0031] (2) mixing the MXene dispersion, sodium hydroxide, urea, and water and precooling the mixture to obtain a mixed dispersion;

[0032] (3) Cellulose and N,N-methylenebisacrylamide were added to the mixed dispersion for gelation, standing, washing and freeze-drying to obtain Ti3C2T x / cellulose aerogel;

[0033] (4) Ti3C2T x / cellulose aerogel is pre-sintered and sintered to obtain TiC / carbon aerogel;

[0034] (5) immersing the TiC / carbon aerogel in an inorganic salt aqueous solution to obtain an inorganic salt / carbon aerogel composite phase change material;

[0035] The inorganic salt aqueous solution is mainly prepared by mixing graphene, Na2HPO4·12H2O and NH4Cl.

[0036] In the present invention, the method for preparing graphene is preferably: using graphite foil as an anode and platinum wire as a cathode to perform electrochemical exfoliation to obtain graphene.

[0037] In the present invention, the electrolyte during the electrochemical stripping is an ammonium sulfate solution, and the voltage is 8 to 12V, preferably 10V.

[0038] In the present invention, the concentration of the ammonium sulfate solution is 0.05 to 0.15 mol / L, preferably 0.1 mol / L.

[0039] In the present invention, the distance between the electrodes during electrochemical stripping is preferably 2 cm.

[0040] In the present invention, vacuum filtration is preferably performed after the electrochemical stripping.

[0041] In the present invention, in step (1), the mass volume ratio of the lithium fluoride and the hydrochloric acid solution is 2g:30~50mL, preferably 2g:35~45mL, and more preferably 2g:40mL; the concentration of the hydrochloric acid solution is 8~10mol / L, preferably 8.5~9.5mol / L, and more preferably 9mol / L; the mass volume ratio of the Ti3AlC2 powder and the hydrochloric acid solution is 2g:30~50mL, preferably 2g:35~45mL, and more preferably 2g:40mL.

[0042] In the present invention, in step (1), the reaction temperature is 30-40°C, preferably 35°C, and the reaction time is 22-26h, preferably 23-25h, and more preferably 24h; the frequency of the ultrasonic treatment is 300-400W, preferably 360-380W, and the reaction time is 10-20min, preferably 12-18min, and more preferably 15min; the rotation speed of the centrifugal treatment is 3000-4000rpm, preferably 3200-3800rpm, and more preferably 3500rpm, and the reaction time is 2-7min, preferably 4-6min, and more preferably 5min.

[0043] In the present invention, in step (2), the mass ratio of MXene, sodium hydroxide, urea and water in the MXene dispersion is 0.02 to 0.3:7:12:81, preferably 0.05 to 0.2:7:12:81, and more preferably 0.0729 to 0.1:7:12:81.

[0044] In the present invention, the pre-cooling temperature is -20 to -15°C, preferably -18°C.

[0045] In the present invention, the mass ratio of the Ti3AlC2 powder to the cellulose is 2:2-3, preferably 2:2.2-2.8, and more preferably 2:2.43-2.6.

[0046] In the present invention, there is no particular limitation on the type of cellulose, as long as it can meet the requirements of the present invention. In the present embodiment, S14009 (produced by Yuanye Company) microcrystalline cellulose is preferably used.

[0047] In the present invention, in step (3), the molar ratio of cellulose to N,N-methylenebisacrylamide is 1:1; ultrasonic treatment is performed during the gelation process, and the ultrasonic treatment time is 0.5 to 1.5 hours; and the static treatment time is 24 to 48 hours.

[0048] In the present invention, in step (3), the freeze-drying temperature is -70 to -50°C, preferably -65 to -55°C, and more preferably -60°C; the time is 44 to 52 hours, preferably 46 to 50 hours, and more preferably 48 hours; and the pressure is 15 to 25 Pa, and preferably 20 Pa.

[0049] In the present invention, in step (4), the heating rate during the pre-sintering is 1 to 3°C / min, preferably 2°C / min, the temperature is 200 to 400°C, preferably 250 to 350°C, more preferably 300°C, and the time is 0.5 to 1.5h, preferably 1h; the heating rate during the sintering is 4 to 6°C / min, preferably 5°C / min, the temperature is 1100 to 1300°C, preferably 1150 to 1250°C, more preferably 1200°C, and the time is 1 to 3h, preferably 1.5 to 2.5h, more preferably 2h.

[0050] In the present invention, in the inorganic salt aqueous solution, the concentration of Na2HPO4·12H2O is 2-5%, preferably 2.5-4%; the concentration of NH4Cl is 0.5-3%, preferably 1-2%; and the concentration of graphene is 0.5-2%, preferably 0.5-1%.

[0051] In the present invention, in step (5), the impregnation is vacuum impregnation, the impregnation time is 4 to 6 minutes, preferably 5 minutes, and the vacuum degree is 0.1 Pa.

[0052] The present invention also provides an inorganic salt / carbon aerogel composite phase change material prepared by the above-mentioned method for preparing the inorganic salt / carbon aerogel composite phase change material.

[0053] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] Graphite foil was cut into 2x2cm squares and used as a carbon electrode (i.e., anode) with a platinum wire as a cathode. The graphite foil and platinum wire were then placed in a 0.1mol / L (NH4)2SO4 solution. Electrochemical exfoliation was then performed by applying a positive voltage of 10V to the graphite foil electrodes, with a distance of 2cm between the anode and cathode. After exfoliation, the graphite foil was filtered through a 0.2μm microporous organic filter membrane, vacuum-filtered, and rinsed several times with deionized water to obtain graphene. The graphene, Na2HPO4·12H2O, NH4Cl, and water were mixed and ultrasonically treated for 30 minutes to prepare an inorganic salt aqueous solution containing 2.5% Na2HPO4·12H2O, 0.75% NH4Cl, and 0.5% graphene. This inorganic salt aqueous solution is the inorganic salt phase change material.

[0056] Under magnetic stirring, 2 g of LiF was dissolved in 40 mL of 9 mol / L hydrochloric acid solution, and then 2 g of Ti3AlC2 powder was added and stirred continuously at 35 ° C for 24 h for reaction. After the reaction, it was repeatedly washed with deionized water and centrifuged for 5 min until the pH value of the supernatant reached 6. Then, the dark green supernatant was further stripped by ultrasonic treatment (360W, 15 min), and centrifuged at 3500 rpm for 5 minutes. This was repeated several times to obtain a MXene dispersion, which was sealed and refrigerated for later use.

[0057] The MXene dispersion, sodium hydroxide, urea, and water were mixed, wherein the mass ratio of MXene, sodium hydroxide, urea, and water in the MXene dispersion was 0.0729:7:12:81. After uniform mixing, the mixture was pre-cooled at -18°C to obtain a mixed dispersion.

[0058] Cellulose (S14009, produced by Yuanye Company) was dried in a vacuum oven at 60°C overnight. 2.43 g of cellulose was stirred in an ice bath for 30 min and then added to the above mixed dispersion. N,N-methylenebisacrylamide (the molar ratio of N,N-methylenebisacrylamide to cellulose was 1:1) was then added. The mixture was ultrasonically treated for 1 h for gelation and then allowed to stand for 24 h. Finally, the mixture was washed and soaked in deionized water several times until the pH value of the soaked deionized water reached 7. The mixture was then freeze-dried at -60°C and 20 Pa for 48 h to obtain Ti3C2T x / cellulose aerogel.

[0059] In nitrogen atmosphere, Ti3C2Tx The TiC / cellulose aerogel was placed in a tubular furnace and heated to 300°C at a heating rate of 2°C / min and kept warm for 1 hour. The temperature was then increased to 1200°C at a heating rate of 5°C / min and kept warm for 2 hours to obtain TiC / carbon aerogel.

[0060] The TiC / carbon aerogel prepared above was placed in a prepared inorganic salt aqueous solution and vacuum impregnated at a vacuum degree of 0.1 Pa for 5 minutes to obtain an inorganic salt / carbon aerogel composite phase change material, which was recorded as MCP.

[0061] Figure 1 The SEM image of graphene clearly shows that the exfoliated graphene flakes only have wrinkles and have a typical two-dimensional layered structure, which provides a favorable prerequisite for constructing a heterogeneous interface.

[0062] The melting temperature, solidification temperature, latent heat and other properties of the inorganic salt / carbon aerogel composite phase change material and the inorganic salt phase change material in Example 1 were measured using a Mettler DSC instrument. Figure 2 As shown in Figure 2, the endothermic and exothermic curves of the inorganic salt phase change material show a single peak, indicating that its components undergo phase change simultaneously. The latent heat of melting, latent heat of solidification, melting temperature, and solidification temperature are 274.54 J / g, 259.8 J / g, -2.05°C, and -17.83°C, respectively. The DSC of the prepared MCP sample is shown in Figure 2. Figure 3 As shown, both the endothermic and exothermic peaks are single peaks, indicating good compatibility between the TiC / carbon aerogel and the inorganic salt phase change material. The latent heat of melting, latent heat of solidification, melting temperature, and solidification temperature are 253.63 J / g, 245.55 J / g, -3.04°C, and -14.17°C, respectively. The decrease in melting temperature and increase in solidification temperature demonstrate that the use of electrochemically exfoliated graphene as a two-dimensional thermally conductive filler and the TiC / carbon aerogel as a three-dimensional porous material self-assemble to form a heterogeneous interface, increasing effective nucleation sites and thereby reducing the energy barrier for phonon scattering and nucleation, thereby reducing supercooling and improving thermal conductivity. The aerogel adsorbed with the inorganic salt phase change material self-assembles to form a dense network hydrogel, promoting the crystallization of the hydrated salt. The confinement effect of the nanomaterials confines the hydrated salt inorganic phase change material within the porous material, maintaining a good latent heat.

[0063] Example 2

[0064] Graphite foil was cut into 2x2cm squares and used as a carbon electrode (i.e., anode) with a platinum wire as a cathode. The graphite foil and platinum wire were then placed in a 0.1mol / L (NH4)2SO4 solution. Electrochemical exfoliation was then performed by applying a positive voltage of 10V to the graphite foil electrodes, with the anode and cathode separated by 2cm. After exfoliation, the graphite foil was filtered through a microporous organic filter membrane with a pore size of 0.2μm, vacuum filtered, and rinsed several times with deionized water to obtain graphene. Graphene, Na2HPO4·12H2O, NH4Cl, and water were mixed and ultrasonically treated for 30 minutes to prepare an inorganic salt aqueous solution, wherein the concentration of Na2HPO4·12H2O was 4%, the concentration of NH4Cl was 2%, and the concentration of graphene was 1%.

[0065] Under magnetic stirring, 2 g of LiF was dissolved in 50 mL of 9 mol / L hydrochloric acid solution, and then 2 g of Ti3AlC2 powder was added and stirred continuously at 40 ° C for 24 h for reaction. After the reaction, it was repeatedly washed with deionized water and centrifuged for 5 min until the pH value of the supernatant was 6. Then, the dark green supernatant was further stripped by ultrasonic treatment (300 W, 20 min), and centrifuged at 3000 rpm for 2 minutes. This was repeated several times to obtain a MXene dispersion, which was sealed and refrigerated for later use.

[0066] The MXene dispersion, sodium hydroxide, urea, and water were mixed, wherein the mass ratio of MXene, sodium hydroxide, urea, and water in the MXene dispersion was 0.02:7:12:81. After mixing evenly, the mixture was pre-cooled at -15°C to obtain a mixed dispersion.

[0067] Cellulose (S14009, produced by Yuanye Company) was dried in a vacuum oven at 60°C overnight. 2 g of cellulose was stirred in an ice bath for 30 min and then added to the above-mentioned mixed dispersion. N,N-methylenebisacrylamide (the molar ratio of N,N-methylenebisacrylamide to cellulose was 1:1) was then added and ultrasonically treated for 1 h for gelation. The mixture was then allowed to stand for 26 h and finally washed and soaked in deionized water several times until the pH value of the soaked deionized water reached 7. The mixture was then freeze-dried at -60°C and 20 Pa for 48 h to obtain Ti3C2T x / cellulose aerogel.

[0068] In nitrogen atmosphere, Ti3C2T x The TiC / cellulose aerogel was placed in a tubular furnace and heated to 300°C at a heating rate of 2°C / min and kept warm for 1 hour. The temperature was then increased to 1200°C at a heating rate of 5°C / min and kept warm for 2 hours to obtain TiC / carbon aerogel.

[0069] The TiC / carbon aerogel prepared above was placed in a prepared inorganic salt aqueous solution and vacuum impregnated at a vacuum degree of 0.1 Pa for 4 minutes to obtain an inorganic salt / carbon aerogel composite phase change material.

[0070] Example 3

[0071] Graphite foil was cut into 2x2cm squares and used as a carbon electrode (i.e., anode) with a platinum wire as a cathode. The graphite foil and platinum wire were then placed in a 0.1mol / L (NH4)2SO4 solution. Electrochemical exfoliation was then performed by applying a positive voltage of 10V to the graphite foil electrodes, with the anode and cathode separated by 2cm. After exfoliation, the graphite foil was filtered through a microporous organic filter membrane with a pore size of 0.2μm, vacuum filtered, and rinsed several times with deionized water to obtain graphene. Graphene, Na2HPO4·12H2O, and NH4Cl were mixed and ultrasonically treated for 30 minutes to prepare an inorganic salt aqueous solution, wherein the concentration of Na2HPO4·12H2O was 5%, the concentration of NH4Cl was 3%, and the concentration of graphene was 2%.

[0072] Under magnetic stirring, 2 g of LiF was dissolved in 30 mL of 9 mol / L hydrochloric acid solution, and then 2 g of Ti3AlC2 powder was added and stirred continuously at 30 ° C for 26 h for reaction. After the reaction, it was repeatedly washed with deionized water and centrifuged for 5 min until the pH value of the supernatant was 6. Then, the dark green supernatant was further stripped by ultrasonic treatment (400 W, 10 min), and centrifuged at 4000 rpm for 7 minutes. This was repeated several times to obtain a MXene dispersion, which was sealed and refrigerated for later use.

[0073] The MXene dispersion, sodium hydroxide, urea, and water were mixed, wherein the mass ratio of MXene, sodium hydroxide, urea, and water in the MXene dispersion was 0.1:7:12:81. After uniform mixing, the mixture was pre-cooled at -15°C to obtain a mixed dispersion.

[0074] Cellulose (S14009, produced by Yuanye Company) was dried in a vacuum oven at 60°C overnight. 3 g of cellulose was stirred in an ice bath for 30 min and then added to the above mixed dispersion. N,N-methylenebisacrylamide (the molar ratio of N,N-methylenebisacrylamide to cellulose was 1:1) was then added and ultrasonically treated for 1 h for gelation. The mixture was then allowed to stand for 48 h and finally washed and soaked in deionized water several times until the pH value of the soaked deionized water reached 7. The mixture was then freeze-dried at -60°C and 20 Pa for 48 h to obtain Ti3C2T x / cellulose aerogel.

[0075] In nitrogen atmosphere, Ti3C2T xThe TiC / cellulose aerogel was placed in a tubular furnace and heated to 300°C at a heating rate of 2°C / min and kept warm for 1 hour. The temperature was then increased to 1200°C at a heating rate of 5°C / min and kept warm for 2 hours to obtain TiC / carbon aerogel.

[0076] The TiC / carbon aerogel prepared above was placed in a prepared inorganic salt aqueous solution and vacuum impregnated at a vacuum degree of 0.1 Pa for 6 minutes to obtain an inorganic salt / carbon aerogel composite phase change material.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing an inorganic salt / carbon aerogel composite phase change material, characterized in that: The steps include: (1) lithium fluoride, hydrochloric acid solution and Ti3AlC2 powder are mixed and reacted, washed, ultrasonically treated and centrifuged to obtain a MXene dispersion; (2) mixing the MXene dispersion, sodium hydroxide, urea, and water and precooling the mixture to obtain a mixed dispersion; (3) Cellulose and N,N-methylenebisacrylamide were added to the mixed dispersion for gelation, standing, washing and freeze-drying to obtain Ti3C2T x / cellulose aerogel; (4) Ti3C2T x / cellulose aerogel is pre-sintered and sintered to obtain TiC / carbon aerogel; (5) immersing the TiC / carbon aerogel in an inorganic salt aqueous solution to obtain an inorganic salt / carbon aerogel composite phase change material; The inorganic salt aqueous solution is mainly prepared by mixing graphene, Na2HPO4·12H2O and NH4Cl.

2. The method for preparing the inorganic salt / carbon aerogel composite phase change material according to claim 1, characterized in that: In step (1), the mass volume ratio of the lithium fluoride and the hydrochloric acid solution is 2g:30~50mL; the concentration of the hydrochloric acid solution is 8~10mol / L; the mass volume ratio of the Ti3AlC2 powder and the hydrochloric acid solution is 2g:30~50mL.

3. The method for preparing the inorganic salt / carbon aerogel composite phase change material according to claim 1 or 2, characterized in that: In step (1), the reaction temperature is 30-40° C., and the reaction time is 22-26 h; the ultrasonic treatment frequency is 300-400 W, and the reaction time is 10-20 min; and the centrifugal treatment speed is 3000-4000 rpm, and the reaction time is 2-7 min.

4. The method for preparing the inorganic salt / carbon aerogel composite phase change material according to claim 3, characterized in that: In step (2), the mass ratio of MXene, sodium hydroxide, urea and water in the MXene dispersion is 0.02-0.3:7:12:

81.

5. The method for preparing the inorganic salt / carbon aerogel composite phase change material according to claim 1, 2 or 4, characterized in that: The mass ratio of the Ti3AlC2 powder to the cellulose is 2:2-3.

6. The method for preparing the inorganic salt / carbon aerogel composite phase change material according to claim 5, characterized in that: In step (3), the molar ratio of cellulose to N,N-methylenebisacrylamide is 1:1; ultrasonic treatment is performed during the gelation process, and the ultrasonic treatment time is 0.5 to 1.5 hours; and the static treatment time is 24 to 48 hours.

7. The method for preparing the inorganic salt / carbon aerogel composite phase change material according to claim 4 or 6, characterized in that: In step (4), the heating rate during the pre-sintering is 1-3°C / min, the temperature is 200-400°C, and the time is 0.5-1.5h; the heating rate during the sintering is 4-6°C / min, the temperature is 1100-1300°C, and the time is 1-3h.

8. The method for preparing the inorganic salt / carbon aerogel composite phase change material according to claim 7, characterized in that: In the inorganic salt aqueous solution, the concentration of Na2HPO4·12H2O is 2-5%, the concentration of NH4Cl is 0.5-3%, and the concentration of graphene is 0.5-2%.

9. The method for preparing the inorganic salt / carbon aerogel composite phase change material according to claim 6 or 8, characterized in that: In step (5), the impregnation is vacuum impregnation, the impregnation time is 4 to 6 minutes, and the vacuum degree is 0.1 Pa.

10. The inorganic salt / carbon aerogel composite phase change material prepared by the method for preparing the inorganic salt / carbon aerogel composite phase change material according to any one of claims 1 to 9.

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