A double-shell-coated hydrated salt phase change microcapsule and its preparation method

Abstract

The present invention relates to the field of phase change microcapsules, and specifically discloses a double-shell coated hydrated salt phase change microcapsule and a preparation method thereof. The method includes the following steps: mixing modified boron nitride with inorganic hydrated salt, heating in a water bath to a temperature 5-20 °C higher than the melting point of the inorganic hydrated salt phase change material, and performing ultrasonic dispersion to obtain component A; mixing modified boron nitride with cyclohexane, and performing ultrasonic dispersion to obtain component B; adding component A to component B, and successively adding a surfactant, a silane coupling agent, a silica precursor and ammonia water under the conditions of constant temperature water bath and stirring, and stirring and reacting for 8-24 hours to obtain component C; washing, filtering and drying component C to obtain the double-shell coated hydrated salt phase change microcapsule.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change microcapsules, and specifically to a double-shell coated hydrated salt phase change microcapsule and a preparation method thereof. Background Art

[0002] Inorganic hydrated salts, as a class of key energy materials, play a crucial role in many important fields such as temperature regulation of power batteries, solar thermal energy conversion, building energy storage, and household heating. However, hydrated inorganic salts have problems such as large supercooling degree, easy phase separation, thermal instability, and low thermal conductivity, which limit their practical applications. It has been found that if hydrated salts are encapsulated as core materials in inorganic or organic shell materials to prepare phase change microcapsules with a core-shell structure, the above problems of hydrated salts can be effectively solved. In the prior art, the shell materials of hydrated salt phase change microcapsules generally consist of organic materials or inorganic materials. Compared with organic shell materials, inorganic shell materials have the advantages of high mechanical strength, good chemical stability, high thermal conductivity, non-flammability, low cost, and environmental optimization, and have attracted extensive attention from researchers.

[0003] However, in the preparation process of the reported phase change microcapsules with inorganic shell materials coated with hydrated salts, generally, the saturated solution of hydrated salts is first coated, and only when the excess free water evaporates can the crystalline hydrated salts precipitate. Moreover, a small amount of crystal water is still converted into free water during the heating and cooling cycles of the hydrated salts, resulting in a decrease in the heat storage capacity of the phase change microcapsules after multiple cycles. In addition, the inorganic shell material is mainly silica with a low thermal conductivity, which limits its heat diffusion rate.

[0004] Chinese Patent CN102676124B discloses an inorganic hydrated salt phase change energy storage microcapsule and a preparation method thereof. The microcapsule uses a saturated salt solution formed by inorganic hydrated salts and deionized water with a relative mass of 20% - 30% as the core material, and a polymer as the shell material. Then, by selecting a suitable organic solvent and assisted by a surfactant, the core material and the shell material are made into a uniformly dispersed mixed solution under ultrasonic action. By adding functional additives such as initiators, lubricants, stabilizers, and polymerization inhibitors, the polymer monomers are suspended and polymerized in the mixed solution under reaction conditions to coat the core material to form phase change microcapsules. This invention patent effectively solves the problems of supercooling and phase separation of the hydrated salt phase change material, but uses a polymer material with flammability and low thermal conductivity as the shell material. The prepared phase change microcapsules are still flammable and have a low thermal conductivity. Deionized water is added during the preparation process, and in addition to inorganic hydrated salts, the core material may contain excess moisture.

[0005] Chinese Patent CN104874337B discloses a preparation method of silica-coated hydrated salt phase change material microcapsules. This invention patent uses the in-situ polymerization method with silica as the shell material to achieve the encapsulation of the hydrated salt phase change material, solving the problems of supercooling, phase separation of the hydrated salt, and leakage during the phase change process of the phase change material. The obtained phase change microcapsules have a relatively large latent heat of phase change. However, this invention patent uses silica with a low thermal conductivity as the shell material, which limits the thermal conductivity of the phase change microcapsules; during the preparation process, the hydrated salt is mixed with a large amount of water to obtain a saturated hydrated salt solution, so in addition to the inorganic hydrated salt, the core material of the prepared phase change microcapsules may contain excess water; this invention patent does not involve the research on the thermal decomposition temperature and thermal decomposition enthalpy of the prepared phase change microcapsules; in addition, this invention patent does not involve the cyclic stability of the prepared phase change microcapsules.

[0006] Chinese Patent CN114316916A discloses a double-layered nano-oxide-coated inorganic hydrated salt phase change material and its preparation method. This invention patent uses inorganic nanoparticles as emulsifiers, hydrated salt materials as the aqueous phase, and organic solvents as the oil phase, reacting with the sol-gel reaction precursor and catalyst to obtain a phase change material; this phase change material solves the problem of failure caused by the contact between free water and the hydrated salt phase change material during the sol-gel reaction due to the presence of inorganic nanoparticles at the oil-water interface in the inverse Pickering emulsion; moreover, the phase change material prepared by coating the hydrated salt with a double-layered inorganic nano-oxide can improve the mechanical strength and thermal conductivity of the material; although the double-layered shell structure is disclosed, this invention patent also does not involve the research on the thermal decomposition temperature, thermal decomposition enthalpy, and cyclic stability of the prepared phase change microcapsules.

[0007] Hexagonal boron nitride (h-BN) is a high-performance material, known for its high thermal stability, excellent electrical insulation, good thermal conductivity, chemical inertness, low density, and lubricity, etc.; it is widely used in fields such as high temperature, electronics, optics, chemistry, and mechanical engineering. In addition, modified boron nitride nanosheets can self-assemble directionally at the oil-water interface to form stable oil-in-water (O / W) and water-in-oil (W / O) type Pickering emulsions. However, there have been no relevant reports on double-layered inorganic hybrid shell-coated hydrated salt phase change microcapsules templated with modified boron nitride nanosheet-stabilized hydrated salt / polar solvents. If modified boron nitride with high thermal conductivity, good thermal stability, and emulsifying properties is used as the stabilizer of the hydrated salt emulsion and the shell material of the phase change microcapsules, it is expected to prepare hydrated salt phase change microcapsules with high thermal conductivity and excellent cyclic stability without introducing free water.

[0008] Therefore, we propose a double-shell-coated hydrated salt phase change microcapsule and its preparation method. Summary of the Invention

[0009] The object of the present invention is to provide a double-shell coated hydrated salt phase change microcapsule and its preparation method to solve the problems raised in the above-mentioned background technology.

[0010] A preparation method of a double-shell coated hydrated salt phase change microcapsule includes the following steps:

[0011] S1: (1) Mix modified boron nitride with inorganic hydrated salt and ultrasonically disperse to obtain component A;

[0012] (2) Mix modified boron nitride with cyclohexane and ultrasonically disperse to obtain component B;

[0013] (3) Add component A to component B, and successively add a surfactant, a silane coupling agent, a silica precursor, and ammonia water under constant temperature water bath and stirring conditions, and stir and react for 8 to 24 hours to obtain component C; wherein, component C is a phase change microcapsule suspension;

[0014] S2: Wash, filter, and dry component C to obtain a double-shell coated hydrated salt phase change microcapsule.

[0015] Preferably, the raw materials of component C include the following components: by mass percentage, 5-20 wt% inorganic hydrated salt, 0.1-1 wt% modified boron nitride, 0.2-1 wt% surfactant, 1-3 wt% silane coupling agent, 5-15 wt% silica precursor, 10-30% ammonia water, and the balance is cyclohexane.

[0016] Preferably, the modified boron nitride is hydroxylated boron nitride nanosheets with a diameter of 50-500 nm and an average diameter <150 nm.

[0017] Preferably, the inorganic hydrated salt includes one or more of sodium thiosulfate pentahydrate, sodium acetate trihydrate, disodium hydrogen phosphate dodecahydrate, sodium sulfate decahydrate, and calcium chloride hexahydrate.

[0018] Preferably, the surfactant includes but is not limited to one or more of cetyltrimethylammonium bromide, sodium dodecyl sulfate, Triton X-100, Tween 80, and Span 80.

[0019] Preferably, in S1, the silane coupling agent includes one or two of 3-aminopropyltriethoxysilane and γ-aminopropyltriethoxysilane.

[0020] Preferably, the silica precursor is tetraethyl orthosilicate.

[0021] Preferably, in (1) and (2) of S1, the ultrasonic dispersion process is the same, that is: the temperature is 5-20 °C higher than the melting point of the inorganic hydrated salt; the ultrasonic power is 400-700 W, and the ultrasonic time is 10-15 minutes.

[0022] Preferably, the water bath temperature is 5-20 °C higher than the melting point of the inorganic hydrated salt, the stirring speed is 400-600 rpm, and the time interval for adding each raw material in sequence is 1-15 minutes.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: In the present invention, modified boron nitride is mixed with inorganic hydrated salt and ultrasonically dispersed to obtain component A; modified boron nitride is mixed with cyclohexane and ultrasonically dispersed to obtain component B; component A is added to component B, and under the conditions of constant temperature water bath and stirring, a surfactant, a silane coupling agent, a silica precursor, and ammonia water are added in sequence, and stirred and reacted for 8-24 hours to obtain component C; component C is washed, filtered, and dried to obtain a double-shell coated hydrated salt phase change microcapsule.

[0024] (1) The hydrated salt coating rate of the double-shell coated hydrated salt phase change microcapsule prepared by the present invention is high, and the phase change heat storage density is large.

[0025] (2) The double-shell coated hydrated salt phase change microcapsule prepared by the present invention has both low-temperature latent heat heat storage (<100 °C) and high-temperature thermal decomposition heat storage (>100 °C) properties. The low-temperature latent heat heat storage originates from the phase change of the hydrated salt, and the phase change enthalpy value is 71.9-148.1 J / g, while the high-temperature stage originates from the thermal decomposition of the hydrated salt, and the thermal decomposition enthalpy value is 306.6-542.8 J / g, which can meet the high heat storage density requirements of different temperature ranges.

[0026] (3) The double-shell coated hydrated salt phase change microcapsule prepared by the present invention uses silica and modified boron nitride nanomaterials with high thermal conductivity as the double-layer shell materials, which solves the problems of core material leakage and the volatilization of free water generated after the melting of the hydrated salt phase change material at low temperatures, improves both the stability of the hydrated salt and the thermal conductivity of the phase change microcapsule.

[0027] (4) The double-shell coated hydrated salt phase change microcapsule prepared by the present invention has good cycle stability. Description of the Drawings

[0028] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0029] Figure 1 is the SEM diagram of the double-shell coated hydrated salt phase change microcapsule prepared in Example 1 of the present invention;

[0030] Figure 2 is the DSC comparison diagram of the double-shell coated hydrated salt phase change microcapsules prepared in Examples 1, 5, and 6 of the present invention;

[0031] Figure 3 DSC diagrams of the double-shell coated hydrated salt phase change microcapsules prepared in Example 1 of the present invention before and after thermal cycling;

[0032] Figure 4 DSC diagram of the silica-coated hydrated salt phase change microcapsules prepared in Comparative Example 1 of the present invention. Specific embodiments

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] In the following description, many specific details are set forth to facilitate a thorough understanding of the present invention. However, the present invention may be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below. In this embodiment, the raw material of the modified boron nitride is hexagonal boron nitride powder, provided by Shanghai Aladdin Reagent Co., Ltd., and obtained by assisted exfoliation through ball milling. The specific preparation method refers to Chinese Patent CN116814223A;

[0035] According to Chinese Patent CN116814223A: Weigh boron nitride nanosheets and sucrose (provided by Shanghai Aladdin Reagent Co., Ltd.) at a mass ratio of 1:5; first mix the boron nitride nanosheets and sucrose, then ball mill for 12 - 14 hours, wash with a large amount of deionized water; ultrasonically disperse for 20 minutes, centrifuge, and freeze-dry to obtain hydroxylated modified boron nitride.

[0036] Sodium thiosulfate pentahydrate, sodium sulfate decahydrate, sodium dodecyl sulfate (SDS), and Triton X-100 are provided by Shanghai Aladdin Reagent Co., Ltd.; cetyltrimethylammonium bromide (CTAB) is provided by Tianjin Damao Chemical Reagent Factory; 3-aminopropyltriethoxysilane (APTs) is provided by Shanghai Macklin Biochemical Co., Ltd.; tetraethyl orthosilicate (TEOs) is provided by Shanghai Macklin Biochemical Co., Ltd.; 25% ammonia water is provided by Shanghai Aladdin Reagent Co., Ltd.; anhydrous ethanol is provided by Tianjin Baishi Chemical Co., Ltd.

[0037] Example 1: A preparation method of double-shell coated hydrated salt phase change microcapsules, including the following operating steps:

[0038] Mix 0.014 g of modified boron nitride with 1.99 g of sodium thiosulfate pentahydrate, heat in a water bath to 60 °C. After the sodium thiosulfate pentahydrate melts, disperse it by ultrasonic wave using a cell crusher. The ultrasonic power is 600 W and the time is 10 minutes to obtain Component A; mix 0.125 g of modified boron nitride with 12.5 g of cyclohexane, heat in a water bath to 60 °C, and disperse it by ultrasonic wave using a cell crusher. The ultrasonic power is 600 W and the time is 10 minutes to obtain Component B; add Component A to Component B. Under the conditions of a constant water bath temperature of 60 °C and a magnetic stirring speed of 500 rpm, add 0.1 g of CTAB and 0.3 mL of APTs in sequence. The time interval for adding the two raw materials is 10 minutes. Then add 2 mL of TEOs, continue stirring for 1 minute, and then add 4.5 mL of 25% ammonia water. Stir and react at a speed of 500 rpm for 16 hours to obtain Component C; pour Component C onto an organic filter membrane for filtration, then wash it 3 times with absolute ethanol, and dry it at room temperature for 48 hours to obtain double-shell coated hydrated salt phase change microcapsules; the phase change enthalpy and decomposition enthalpy of the double-shell coated hydrated salt phase change microcapsules are 125.6 J / g and 522.2 J / g respectively. After multiple heating and cooling cycles, the phase change enthalpy and decomposition enthalpy of the phase change microcapsules are 117.1 J / g and 498.6 J / g respectively, and the cycle stability is good.

[0039] Example 2: A preparation method of double-shell coated hydrated salt phase change microcapsules, including the following operation steps:

[0040] Mix 0.014 g of modified boron nitride with 1.9 g of sodium thiosulfate pentahydrate, heat in a water bath to 60 °C. After the sodium thiosulfate pentahydrate melts, disperse it by ultrasonic wave using a cell crusher. The ultrasonic power is 600 W and the time is 10 minutes to obtain Component A; mix 0.125 g of modified boron nitride with 12.5 g of cyclohexane, heat in a water bath to 60 °C, and disperse it by ultrasonic wave using a cell crusher. The ultrasonic power is 600 W and the time is 1 minute to obtain Component B; add Component A to Component B. Under the conditions of a constant water bath temperature of 60 °C and a magnetic stirring speed of 500 rpm, add 0.1 g of CTAB, continue stirring for 15 minutes, add 0.3 mL of FD-550, then quickly add 2 mL of TEOs, stir for 10 minutes, and then add 3 mL of 25% ammonia water. Continue heating and stirring in a water bath at a temperature of 60 °C and a speed of 500 rpm for 16 hours to obtain Component C; pour Component C onto an organic filter membrane for filtration, then wash it 3 times with absolute ethanol, and dry it at room temperature for 48 hours to obtain double-shell coated hydrated salt phase change microcapsules; the phase change enthalpy and decomposition enthalpy of the double-shell coated hydrated salt phase change microcapsules are 112 J / g and 449.8 J / g respectively.

[0041] Example 3: A preparation method of double-shell coated hydrated salt phase change microcapsules, including the following operation steps:

[0042] Mix 0.02 g of modified boron nitride with 2.48 g of sodium sulfate decahydrate, heat in a water bath to 45 °C, and after the sodium sulfate decahydrate melts, disperse it by ultrasonic wave using a cell disruptor with an ultrasonic power of 500 W for 15 minutes to obtain Component A; mix 0.125 g of modified boron nitride with 12.5 g of cyclohexane, heat in a water bath to 45 °C, and disperse it by ultrasonic wave using a cell disruptor with an ultrasonic power of 600 W for 12 minutes to obtain Component B; add Component A to Component B, under the conditions of a constant water bath temperature of 45 °C and a magnetic stirring speed of 500 rpm, add 0.1 g of CTAB, continue stirring for 15 minutes, add 0.4 mL of APTs, then quickly add 2 mL of TEOs, stir for 12 minutes, add 4.5 mL of 25% ammonia water, continue heating and stirring in a water bath at a temperature of 45 °C and a speed of 500 rpm, and react for 16 hours to obtain Component C; pour Component C onto an organic filter membrane for filtration, then wash it 3 times with absolute ethanol, and dry it at room temperature for 72 hours to obtain double-shell coated hydrated salt phase change microcapsules; the phase change enthalpy and decomposition enthalpy of the double-shell coated hydrated salt phase change microcapsules are 101.1 J / g and 364.5 J / g respectively.

[0043] Example 4: A preparation method of double-shell coated hydrated salt phase change microcapsules, comprising the following operating steps:

[0044] Mix 0.011 g of modified boron nitride with 1.49 g of sodium thiosulfate pentahydrate, heat in a water bath to 60 °C, and after the sodium thiosulfate pentahydrate melts, disperse it by ultrasonic wave using a cell disruptor with an ultrasonic power of 650 W for 8 minutes to obtain Component A; mix 0.125 g of modified boron nitride with 12.5 g of cyclohexane, heat in a water bath to 60 °C, and disperse it by ultrasonic wave using a cell disruptor with an ultrasonic power of 550 W for 11 minutes to obtain Component B; add Component A to Component B, under the conditions of a constant water bath temperature of 60 °C and a magnetic stirring speed of 500 rpm, add 0.1 g of SDS, continue stirring for 15 minutes, add 0.2 mL of APTs, then quickly add 2 mL of TEOs, stir for 10 minutes, add 3 mL of 25% ammonia water, continue heating and stirring in a water bath at a temperature of 60 °C and a speed of 500 rpm, and react for 16 hours to obtain Component C; pour Component C onto an organic filter membrane for filtration, then wash it 3 times with absolute ethanol, and dry it at room temperature for 48 hours to obtain double-shell coated hydrated salt phase change microcapsules; the phase change enthalpy and decomposition enthalpy of the double-shell coated hydrated salt phase change microcapsules are 88.4 J / g and 366.7 J / g respectively.

[0045] Example 5: A preparation method of double-shell coated hydrated salt phase change microcapsules, comprising the following operating steps:

[0046] Mix 0.022 g of modified boron nitride with 2.98 g of sodium thiosulfate pentahydrate, heat in a water bath to 60 °C. After the sodium thiosulfate pentahydrate melts, disperse it by ultrasonic treatment with a cell disruptor at an ultrasonic power of 600 W for 10 minutes to obtain Component A; mix 0.125 g of modified boron nitride with 12.5 g of cyclohexane, heat in a water bath to 60 °C, and disperse it by ultrasonic treatment with a cell disruptor at an ultrasonic power of 600 W for 10 minutes to obtain Component B; add Component A to Component B, under the conditions of a constant water bath temperature of 60 °C and a magnetic stirring speed of 500 rpm, add 0.1 g of CTAB, continue stirring for 15 minutes, add 0.5 mL of APTs, then quickly add 3 mL of TEOs, stir for 12 minutes, add 6 mL of 25% ammonia water, continue heating and stirring in a water bath at a temperature of 60 °C and a speed of 500 rpm, react for 16 hours to obtain Component C; pour Component C onto an organic filter membrane for filtration, then wash it 3 times with absolute ethanol, and dry it at room temperature for 72 hours to obtain double-shell coated hydrated salt phase change microcapsules; the phase change enthalpy and decomposition enthalpy of the double-shell coated hydrated salt phase change microcapsules are 148.1 J / g and 603.1 J / g respectively.

[0047] Example 6: A preparation method of double-shell coated hydrated salt phase change microcapsules, comprising the following operating steps:

[0048] Mix 0.011 g of modified boron nitride with 1.49 g of sodium thiosulfate pentahydrate, heat in a water bath to 60 °C. After the sodium thiosulfate pentahydrate melts, disperse it by ultrasonic treatment with a cell disruptor at an ultrasonic power of 600 W for 10 minutes to obtain Component A; mix 0.125 g of modified boron nitride with 12.5 g of cyclohexane, heat in a water bath to 60 °C, and disperse it by ultrasonic treatment with a cell disruptor at an ultrasonic power of 600 W for 10 minutes to obtain Component B; add Component A to Component B, under the conditions of a constant water bath temperature of 60 °C and a magnetic stirring speed of 500 rpm, add 0.1 g of TritonX-100, continue stirring for 12 minutes, add 0.1 mL of APTs, then quickly add 2 mL of TEOs, stir for 12 minutes, add 3 mL of 25% ammonia water, continue heating and stirring in a water bath at a temperature of 60 °C and a speed of 500 rpm, react for 16 hours to obtain Component C; pour Component C onto an organic filter membrane for filtration, then wash it 3 times with absolute ethanol, and dry it at room temperature for 72 hours to obtain double-shell coated hydrated salt phase change microcapsules; the phase change enthalpy and decomposition enthalpy of the double-shell coated hydrated salt phase change microcapsules are 71.9 J / g and 306.6 J / g respectively.

[0049] Comparative Example 1 is silica-coated hydrated salt phase change microcapsules;

[0050] Heat 2 g of sodium thiosulfate pentahydrate in a water bath to 60 °C until the sodium thiosulfate pentahydrate is completely melted to obtain Component A; heat 12.5 g of cyclohexane in a water bath to 60 °C to obtain Component B; add Component A to Component B, and under the conditions of a constant water bath temperature of 60 °C and a magnetic stirring speed of 500 rpm, sequentially add 0.1 g of CTAB and 0.3 mL of APTs, with a time interval of 10 minutes between the addition of the two raw materials. Then quickly add 2 mL of TEOs, continue stirring for 10 minutes, add 4.5 mL of 25% ammonia water, continue heating and stirring in a water bath at a temperature of 60 °C and a speed of 500 rpm, and react for 16 hours to obtain Component C; pour Component C onto an organic filter membrane for filtration, wash it 3 times with absolute ethanol, and dry it at room temperature for 48 hours to obtain double-shell coated hydrated salt phase change microcapsules; there is only one thermal decomposition peak in the DSC diagram of the double-shell coated hydrated salt phase change microcapsules, with almost no phase change enthalpy, and the decomposition enthalpy is 208.6 J / g.

[0051] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0052] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing double-shell coated hydrated salt phase change microcapsules, characterized in that: The following steps are involved: S1: (1) mixing hydroxylated boron nitride nanosheets with inorganic hydrated salt, and ultrasonically dispersing the mixture to obtain component A; (2) mixing hydroxylated boron nitride nanosheets with cyclohexane and dispersing by ultrasonication to obtain component B; (3) Add component A to component B, and add surfactant, silane coupling agent, silica precursor and ammonia water in sequence under constant temperature water bath and stirring conditions, and stir to react for 8 to 24 hours to obtain component C; S2: washing, filtering and drying component C to obtain double-shelled hydrated salt phase change microcapsules; The raw materials of component C include the following components: in mass percentage, 5-20wt% of inorganic hydrated salt, 0.1-1wt% of hydroxylated boron nitride nanosheets, 0.2-1wt% of surfactant, 1-3wt% of silane coupling agent, 5-15wt% of silicon dioxide precursor, 10-30% of ammonia water, and the balance is cyclohexane.

2. The method for preparing a double-shell coated hydrated salt phase change microcapsule according to claim 1, characterized in that: The diameter of the hydroxylated boron nitride nanosheets is 50-500 nm, and the average diameter is less than 150 nm.

3. The method for preparing a double-shell coated hydrated salt phase change microcapsule according to claim 1, characterized in that: The inorganic hydrated salt includes one or more of sodium thiosulfate pentahydrate, sodium acetate trihydrate, disodium hydrogen phosphate dodecahydrate, sodium sulfate decahydrate, and calcium chloride hexahydrate.

4. The method for preparing a double-shell coated hydrated salt phase change microcapsule according to claim 1, characterized in that: The surfactant includes one or more of cetyltrimethylammonium bromide, sodium lauryl sulfate, Triton X-100, Tween 80 and Span 80.

5. The method for preparing a double-shell coated hydrated salt phase change microcapsule according to claim 1, characterized in that: In S1, the silane coupling agent includes one or both of 3-aminopropyltriethoxysilane and γ-aminopropyltriethoxysilane.

6. The method for preparing a double-shell coated hydrated salt phase change microcapsule according to claim 1, characterized in that: The silicon dioxide precursor is tetraethyl silicate.

7. The method for preparing a double-shell coated hydrated salt phase change microcapsule according to claim 1, characterized in that: In (1) and (2) of S1, the ultrasonic dispersion process is the same, that is, the temperature is 5-20°C higher than the melting point of the inorganic hydrated salt; the ultrasonic power is 400-700W; and the ultrasonic time is 10-15 minutes.

8. The method for preparing a double-shell coated hydrated salt phase change microcapsule according to claim 1, characterized in that: The water bath temperature is 5-20° C. higher than the melting point of the inorganic hydrated salt, the stirring speed is 400-600 rpm, and the time interval between each raw material when adding them sequentially is 1-15 minutes.

9. Double-shell coated hydrated salt phase change microcapsules are prepared according to the method for preparing double-shell coated hydrated salt phase change microcapsules according to any one of claims 1 to 8.

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