Solid-solid phase change energy storage material and preparation method thereof
By calcining the elolite and hydrophobizing the methyl trimethoxysilane, a mesoporous structure is formed, which solves the problem of latent heat reduction in phase change caused by excessive iron platinum, and achieves efficient polyethylene glycol adsorption and energy storage.
Patent Information
- Application Number
- CN202510523303.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-08-08
AI Technical Summary
In the prior art, excessive amount of iron platinum will lead to a decrease in the latent heat of phase change of solid-solid phase change energy storage materials, affecting the adsorption effect of polyethylene glycol.
Using modified matrix materials, a mesoporous structure is formed by calcining on Elosite and hydrophobizing with methyl trimethoxysilane to ensure that iron platinum is preferred to be deposited on the outer surface, the inner cavity is unobstructed, and the polyethylene glycol molecular chain is highly adsorbed through the inner cavity.
The latent heat of phase change of solid-solid phase change energy storage materials is improved, the adsorption capacity of polyethylene glycol is enhanced, and the energy storage performance of the material is improved.
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Figure CN120442220A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of phase change energy storage materials, and in particular relates to a solid-solid phase change energy storage material and a preparation method thereof. Background Art
[0002] Solid-solid phase change energy storage material is a functional material that achieves energy storage and release through the reversible transformation of the lattice structure or molecular arrangement inside the solid material (i.e. solid-solid phase change). Its core feature is that the phase change process only occurs inside the solid state and does not involve solid-liquid or solid-gas transformation. Therefore, it has the advantages of no leakage, stable structure, and long cycle life. The energy storage mechanism of solid-solid phase change energy storage material is to absorb / release latent heat through the transformation of molecular order-disorder arrangement or chemical bond reorganization. The heat storage density is significantly higher than sensible heat storage (such as ordinary materials absorbing heat when heating up). In addition, the solid-solid phase change energy storage material remains in a solid state as a whole during the phase change process, with small temperature fluctuations, which is suitable for precise temperature control scenarios.
[0003] Existing solid-solid phase change energy storage materials, prepared using a physical blending method using polyethylene glycol as the phase change material, halloysite as the matrix material, and iron platinum as the third phase, exhibit a production process in which, given a given amount of polyethylene glycol and halloysite, the final solid-solid phase change energy storage material's latent heat of phase change initially increases with increasing iron platinum content, then decreases. This indicates that the specific amount of iron platinum affects the halloysite's adsorption of polyethylene glycol. Excessive iron platinum usage results in a decrease in the final solid-solid phase change energy storage material's latent heat of phase change. Summary of the Invention
[0004] In order to solve the problems existing in the background technology, the present invention provides a solid-solid phase change energy storage material and a preparation method thereof, which can effectively increase the phase change latent heat of the prepared solid-solid phase change energy storage material.
[0005] In order to achieve the above objectives, in a first aspect, the present invention provides a method for preparing a solid-solid phase change energy storage material, comprising the following steps:
[0006] S1. Add 2.12-2.18 g of ferric acetylacetonate and 7 g of the modified matrix to anhydrous ethanol, stir under a magnetic stirrer for 30 min, then slowly add a hexahydrate chloroplatinic acid ethanol solution, which includes 1.5-1.54 g of hexahydrate chloroplatinic acid, in a three-necked flask, and stir for 30 min under an argon environment to obtain a primary solution;
[0007] S2. Slowly add a sodium borohydride ethanol solution containing 11.75-12.35 g of sodium borohydride to the primary solution obtained in S1. After the addition is complete, heat it in a water bath at 40±2°C for 2 hours, wash and dry it to obtain a matrix - iron platinum;
[0008] S3. Add polyethylene glycol ethanol solution obtained by dissolving polyethylene glycol in anhydrous ethanol and stirring at 30°C for 30 minutes to the matrix-iron platinum obtained in S2, which includes 12.8-13.2g polyethylene glycol, stir for 30 minutes, ultrasonically disperse for 30 minutes, and finally place in a water bath at 80±2°C and heat with stirring to volatilize the ethanol, and then dry to obtain a solid-solid phase change energy storage material;
[0009] The modified matrix is prepared by calcining halloysite and then subjecting it to hydrophobic treatment with methyltrimethoxysilane.
[0010] Furthermore, the preparation method of the modified matrix is as follows:
[0011] A1. In an argon atmosphere, halloysite is placed in a tube furnace, heated to 450-550°C, and kept at this temperature for 2-3 hours to remove structural hydroxyl groups and form mesopores. The calcined halloysite is obtained by naturally cooling to room temperature to avoid sudden cooling that may cause pore collapse.
[0012] A2, adding the calcined halloysite obtained in A1 to anhydrous ethanol, and ultrasonically treating the mixture to activate the surface to obtain a halloysite suspension;
[0013] A3, dissolving methyltrimethoxysilane in anhydrous ethanol to obtain a surface modification solution;
[0014] A4. Add the surface modification liquid obtained in A3 dropwise to the halloysite suspension obtained in A2, where the mass of the methyltrimethoxysilane is 6-8% of the mass of the halloysite. After stirring at 48-52°C for 6-6.5 hours, add deionized water to terminate the reaction. After centrifugation, wash with ethanol several times to remove unreacted methyltrimethoxysilane, and dry to obtain a modified matrix.
[0015] Furthermore, in A1, the heating rate is 4-5°C / min.
[0016] Furthermore, in A2, the mass ratio of the calcined halloysite to anhydrous ethanol is 1:(40-45).
[0017] Furthermore, in A2, the ultrasonic treatment frequency is 40-50 KHz, and the ultrasonic treatment time is 30-40 min.
[0018] Furthermore, in A3, the concentration of methyltrimethoxysilane in the surface modification solution is 0.3-0.5 mol / L.
[0019] Furthermore, in S1, the preparation method of the chloroplatinic acid hexahydrate ethanol solution is: add 1 g of chloroplatinic acid hexahydrate to 90-110 mL of anhydrous ethanol, and stir with a magnetic stirrer to make it uniform.
[0020] Furthermore, in S2, the sodium borohydride ethanol solution is prepared by adding 1 g of sodium borohydride to 250-265 mL of anhydrous ethanol and heating in a water bath at 25° C. until dissolved.
[0021] In a second aspect, the present invention provides a solid-solid phase change energy storage material, which is prepared using the above-mentioned preparation method.
[0022] This application has the following beneficial effects:
[0023] The invention uses halloysite as a matrix material and uses an excess of iron and platinum to prepare a modified matrix. The modified matrix is prepared by calcining the halloysite and then subjecting it to a hydrophobic treatment with methyltrimethoxysilane.
[0024] On the one hand, when halloysite is calcined at 450-550°C, the Si-OH groups on the outer surface are partially removed due to direct exposure to high temperatures, while the Al-OH groups in the inner cavity are less removed due to the spatial constraints of the halloysite tubular structure and the high thermal stability of aluminum hydroxyl groups (Al-OH), thus maintaining the hydrophilicity of the inner cavity. In other words, calcination primarily removes the outer surface hydroxyl groups and forms a mesoporous structure (expanding the pore diameter), while the Al-OH groups in the inner cavity remain more due to spatial constraints. Iron platinum originally preferentially deposits on the outer surface or at the pore openings, but the expansion of the mesopore diameter reduces iron platinum particles' blockage of the inner cavity, ensuring a patency of the inner cavity and enhancing the ability of polyethylene glycol molecular chains to embed.
[0025] On the other hand, methyltrimethoxysilane preferentially reacts with the Si-OH groups remaining on the outer surface of calcined halloysite to form a hydrophobic Si-O-Si(CH3)3 layer. However, the inner cavity is less hydrophobic due to the low activity of Al-OH and spatial limitations. When the degree of lumen blockage caused by excessive iron platinum deposition is weakened and offset by the mesoporous structure (pore size expansion) brought about by the calcination treatment, the hydrophobic outer surface repels the more polar polyethylene glycol molecular chains, forcing them to enter the pores through the hydrophilic inner cavity. However, the inner cavity / pores still retain sufficient Al-OH and polar silicon-oxygen skeletons to efficiently adsorb polyethylene glycol through hydrogen bonds and van der Waals forces.
[0026] In this way, the two treatment methods of the matrix material halloysite (calcination treatment and methyltrimethoxysilane external surface hydrophobic modification treatment) produce a synergistic effect, synergistically improving the phase change enthalpy of the solid-solid phase change energy storage material. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 , a comparative trend diagram of the phase change enthalpy test data of the solid-solid phase change energy storage materials obtained in Examples 1 to 3 and Comparative Examples 1 to 5 in the test examples of the present invention. DETAILED DESCRIPTION
[0028] The present application is further described in detail below with reference to the embodiments.
[0029] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.
[0030] Example 1: (1) Preparation of a modified matrix, the preparation method is as follows:
[0031] A1. In an argon atmosphere, halloysite was placed in a tube furnace and heated to 500°C at a heating rate of 5°C / min. The temperature was maintained for 2.5 hours to remove structural hydroxyl groups and form mesopores. The material was then naturally cooled to room temperature to avoid sudden cooling that would cause pore collapse, thereby obtaining calcined halloysite.
[0032] A2. The calcined halloysite obtained in A1 was added to anhydrous ethanol, with a mass ratio of calcined halloysite to anhydrous ethanol of 1:43. The ultrasonic treatment frequency was 45 kHz and the ultrasonic treatment time was 35 min to activate the surface and obtain a halloysite suspension.
[0033] A3. Dissolve methyltrimethoxysilane in anhydrous ethanol to obtain a surface modification solution. The concentration of methyltrimethoxysilane in the surface modification solution is 0.4 mol / L.
[0034] A4. Add the surface modification liquid obtained in A3 dropwise to the halloysite suspension obtained in A2, with the mass of methyltrimethoxysilane being 7% of the mass of the halloysite. Stir uniformly at a stirring speed of 240 r / min at about 50°C for 6.2 h, then add deionized water to terminate the reaction. After centrifugation, wash three times with ethanol to remove unreacted methyltrimethoxysilane, and dry to obtain a modified matrix.
[0035] (2) Prepare solid-solid phase change energy storage material, the preparation method is as follows:
[0036] S1, 2.16g ferric acetylacetonates and 7g modified matrix are added in dehydrated alcohol, at the uniform velocity stirring 30min under magnetic stirring apparatus 280r / min stirring speed, it is then slowly added into chloroplatinic acid hexahydrate ethanolic solution, it includes 1.52g chloroplatinic acid hexahydrate, in there-necked flask, under argon environment, continues to stir at the uniform velocity stirring 30min with the stirring speed of 280r / min, obtains primary solution.Wherein, the configuration method of chloroplatinic acid hexahydrate ethanolic solution is: 1g chloroplatinic acid hexahydrate is added in 100mL dehydrated alcohol, stirs it evenly with magnetic stirring apparatus, to obtain final product.
[0037] S2. Slowly dropwise add 12.0 g of sodium borohydride in ethanol to the primary solution obtained in S1. After the addition is complete, incubate in a 40±2°C water bath for 2 hours, wash, and dry to obtain the matrix-iron platinum. The sodium borohydride in ethanol solution is prepared by adding 1 g of sodium borohydride to 260 mL of anhydrous ethanol and heating in a 25°C water bath until dissolved.
[0038] S3. Add polyethylene glycol to the matrix-iron platinum obtained in S2, dissolve it with 10 times its mass of anhydrous ethanol and stir it at 30°C at a stirring speed of 220r / min for 30 minutes to obtain a polyethylene glycol ethanol solution, which includes 13.0g polyethylene glycol, uniformly stirred at a stirring speed of 220r / min for 30 minutes, and then ultrasonically dispersed at 35KHz for 30 minutes, and finally placed in a water bath at 80±2°C and heated at a constant temperature and continuously stirred at a stirring speed of 220r / min for 2 hours to volatilize the ethanol, and then dried to obtain a solid-solid phase change energy storage material.
[0039] Iron acetylacetonate Fe(acac)3 (effective substance content 99%) was purchased from Shanghai Liming Chemical Co., Ltd. Chloroplatinic acid hexahydrate (99%) was purchased from Hubei Chenghai Chemical Co., Ltd. Sodium borohydride (≥98%) was purchased from Aozun Composite New Materials Co., Ltd. Polyethylene glycol (PEG-7000) was purchased from Hai'an Petrochemical Plant in Jiangsu Province.
[0040] Example 2: The difference between this example and Example 1 is that: (1) a modified matrix is prepared, and the preparation method is as follows:
[0041] A1. In an argon atmosphere, halloysite was placed in a tube furnace and heated to 500°C at a heating rate of 5°C / min. The temperature was maintained for 2.5 hours to remove structural hydroxyl groups and form mesopores. The material was then naturally cooled to room temperature to avoid sudden cooling that would cause pore collapse, thereby obtaining calcined halloysite.
[0042] A2. The calcined halloysite obtained in A1 was added to anhydrous ethanol, with a mass ratio of calcined halloysite to anhydrous ethanol of 1:40. The ultrasonic treatment frequency was 40 kHz and the ultrasonic treatment time was 40 min to activate the surface and obtain a halloysite suspension.
[0043] A3. Dissolve methyltrimethoxysilane in anhydrous ethanol to obtain a surface modification solution. The concentration of methyltrimethoxysilane in the surface modification solution is 0.3 mol / L.
[0044] A4. Add the surface modification liquid obtained in A3 dropwise to the halloysite suspension obtained in A2, with the mass of methyltrimethoxysilane being 6% of the mass of the halloysite. Stir uniformly at a stirring speed of 240 r / min at about 50°C for 6 hours, then add deionized water to terminate the reaction. After centrifugation, wash three times with ethanol to remove unreacted methyltrimethoxysilane, and dry to obtain a modified matrix.
[0045] (2) Prepare solid-solid phase change energy storage material, the preparation method is as follows:
[0046] S1, 2.18g ferric acetylacetonates and 7g modified matrix are added in dehydrated alcohol, at the uniform velocity stirring 30min under magnetic stirring apparatus 280r / min stirring speed, it is then slowly added into chloroplatinic acid hexahydrate ethanolic solution, it includes 1.54g chloroplatinic acid hexahydrate, in there-necked flask, under argon environment, continues to stir at the uniform velocity stirring 30min with the stirring speed of 280r / min, obtains primary solution.Wherein, the configuration method of chloroplatinic acid hexahydrate ethanolic solution is: 1g chloroplatinic acid hexahydrate is added in 100mL dehydrated alcohol, stirs it evenly with magnetic stirring apparatus, to obtain final product.
[0047] S2. Slowly add a sodium borohydride ethanol solution containing 12.35 g of sodium borohydride to the primary solution obtained in S1. After the addition is complete, the solution is incubated in a 40±2°C water bath for 2 hours, washed, and dried to obtain the matrix-iron platinum. The sodium borohydride ethanol solution is prepared by adding 1 g of sodium borohydride to 260 mL of anhydrous ethanol and heating in a 25°C water bath until dissolved.
[0048] S3. Add polyethylene glycol to the matrix-iron platinum obtained in S2, dissolve it with 10 times its mass of anhydrous ethanol and stir it at 30°C at a stirring speed of 220r / min for 30 minutes to obtain a polyethylene glycol ethanol solution, which includes 13.2g of polyethylene glycol, uniformly stirred at a stirring speed of 220r / min for 30 minutes, and then ultrasonically dispersed at 35KHz for 30 minutes, and finally placed in a water bath at 80±2°C and heated at a constant temperature and continuously stirred at a stirring speed of 220r / min for 2 hours to volatilize the ethanol, and then dried to obtain a solid-solid phase change energy storage material.
[0049] Example 3: The difference between this example and Example 1 is that: (1) a modified matrix is prepared, and the preparation method is as follows:
[0050] A1. In an argon atmosphere, halloysite was placed in a tube furnace and heated to 500°C at a heating rate of 5°C / min. The temperature was maintained for 3 hours to remove structural hydroxyl groups and form mesopores. The material was then naturally cooled to room temperature to avoid sudden cooling that would cause pore collapse, thereby obtaining calcined halloysite.
[0051] A2. The calcined halloysite obtained in A1 was added to anhydrous ethanol, with a mass ratio of calcined halloysite to anhydrous ethanol of 1:45. The ultrasonic treatment frequency was 50 kHz and the ultrasonic treatment time was 30 min to activate the surface and obtain a halloysite suspension.
[0052] A3. Dissolve methyltrimethoxysilane in anhydrous ethanol to obtain a surface modification solution. The concentration of methyltrimethoxysilane in the surface modification solution is 0.5 mol / L.
[0053] A4. Add the surface modification liquid obtained in A3 dropwise to the halloysite suspension obtained in A2, with the mass of methyltrimethoxysilane being 8% of the mass of the halloysite. Stir uniformly at a stirring speed of 240 r / min at about 50°C for 6.5 h, then add deionized water to terminate the reaction. After centrifugation, wash three times with ethanol to remove unreacted methyltrimethoxysilane, and dry to obtain a modified matrix.
[0054] (2) Prepare solid-solid phase change energy storage material, the preparation method is as follows:
[0055] S1, 2.12g ferric acetylacetonates and 7g modified matrix are added in absolute ethanol, at the uniform velocity stirring 30min under magnetic stirring apparatus 280r / min stirring speed, it is then slowly added into chloroplatinic acid hexahydrate ethanolic solution, it includes 1.5g chloroplatinic acid hexahydrate, in there-necked flask, under argon environment, continues to stir at the uniform velocity stirring 30min with the stirring speed of 280r / min, obtains primary solution.Wherein, the configuration method of chloroplatinic acid hexahydrate ethanolic solution is: 1g chloroplatinic acid hexahydrate is added in 100mL absolute ethanol, stirs it evenly with magnetic stirring apparatus, to obtain final product.
[0056] S2. Slowly dropwise add 11.75 g of sodium borohydride in ethanol to the primary solution obtained in S1. After the addition is complete, incubate in a 40±2°C water bath for 2 hours, wash, and dry to obtain the matrix-iron platinum. The sodium borohydride in ethanol solution is prepared by adding 1 g of sodium borohydride to 260 mL of anhydrous ethanol and heating in a 25°C water bath until dissolved.
[0057] S3. Add polyethylene glycol to the matrix-iron platinum obtained in S2, dissolve it with 10 times its mass of anhydrous ethanol and stir it at 30°C at a stirring speed of 220r / min for 30 minutes to obtain a polyethylene glycol ethanol solution, which includes 12.8g polyethylene glycol, uniformly stirred at a stirring speed of 220r / min for 30 minutes, and then ultrasonically dispersed at 35KHz for 30 minutes, and finally placed in a water bath at 80±2°C for constant temperature heating and continuous stirring at a stirring speed of 220r / min for 2 hours to volatilize the ethanol, and then dried to obtain a solid-solid phase change energy storage material.
[0058] Comparative Example 1: The difference between this comparative example and Example 1 is that in the preparation of the solid-solid phase change energy storage material, the modified matrix is replaced by halloysite; and the amount of ferric acetylacetonate is reduced from 2.16g to 2.0g, and the amount of chloroplatinic acid hexahydrate is reduced from 1.52g to 1.42g.
[0059] Comparative Example 2: The difference between this comparative example and Example 1 is that in the preparation of the solid-solid phase change energy storage material, the modified matrix is replaced by halloysite.
[0060] Comparative Example 3: The difference between this comparative example and Example 1 is that in the preparation of the solid-solid phase change energy storage material, the amount of ferric acetylacetonate is reduced from 2.16g to 2.0g, and the amount of chloroplatinic acid hexahydrate is reduced from 1.52g to 1.42g.
[0061] Comparative Example 4: This comparative example differs from Example 1 in that, in the preparation of the modified substrate, calcined halloysite was replaced with halloysite. (That is, the calcination of the halloysite was omitted, and the halloysite was directly subjected to the hydrophobic modification of the outer surface with methyltrimethoxysilane.)
[0062] Specifically, the modified matrix is prepared as follows:
[0063] A1. Halloysite was added to anhydrous ethanol at a mass ratio of 1:43. The ultrasonic treatment frequency was 45 kHz and the ultrasonic treatment time was 35 min to activate the surface and obtain a halloysite suspension.
[0064] A2. Dissolve methyltrimethoxysilane in anhydrous ethanol to obtain a surface modification solution. The concentration of methyltrimethoxysilane in the surface modification solution is 0.4 mol / L.
[0065] A3. Add the surface modification liquid obtained in A2 dropwise to the halloysite suspension obtained in A1, with the mass of methyltrimethoxysilane being 7% of the mass of the halloysite. Stir uniformly at a stirring speed of 240 r / min at about 50°C for 6.2 h, then add deionized water to terminate the reaction. After centrifugation, wash three times with ethanol to remove unreacted methyltrimethoxysilane, and dry to obtain a modified matrix.
[0066] Comparative Example 5: This comparative example differs from Example 1 in that the modified substrate is replaced with calcined halloysite. (That is, only the halloysite is calcined, and the hydrophobic modification of the calcined halloysite with methyltrimethoxysilane is omitted.)
[0067] Test Example: Test subjects: Solid-solid phase change energy storage materials were prepared using Examples 1-3 and Comparative Examples 1-5. Test Items: ① Phase transition temperature; ② Phase transition enthalpy ΔH (J / g). Test results: See Table 1.
[0068] Table 1. Test data of experimental example
[0069]
[0070]
[0071] Result analysis: Analyze Example 1-Example 3 and Comparative Example 1-Comparative Example 5 and combine the data in Table 1 and Figure 1 It can be seen that the phase transition temperature of the solid-solid phase change energy storage materials prepared in the embodiments and comparative examples is 60±0.3° C., with no significant difference.
[0072] A specific analysis of Examples 1 to 3 shows that the phase change enthalpy of the solid-solid phase change energy storage material prepared in the present invention (Examples 1 to 3) reaches above 80.5 J / g.
[0073] By comparing Comparative Example 1 and Comparative Example 2 (both of which have a matrix material of halloysite), it can be seen that the amount of ferric acetylacetonate in Comparative Example 2 is increased from 2.0g (Comparative Example 1) to 2.16g, and the amount of chloroplatinic acid hexahydrate is increased from 1.42g (Comparative Example 1) to 1.52g; As a result, the phase change enthalpy of the solid-solid phase change energy storage material obtained in Comparative Example 2 (compared with Comparative Example 1) is significantly reduced, indicating that when the matrix material is halloysite, increasing the amount of ferric acetylacetonate from 2.0g to 2.16g and increasing the amount of chloroplatinic acid hexahydrate from 1.42g to 1.52g will result in a decrease in the phase change enthalpy of the solid-solid phase change energy storage material. This is because polyethylene glycol originally needs to form a helical conformation in the pores of halloysite to achieve efficient phase transition, but excessive deposition of iron platinum will block the lumen and surface pores of halloysite, resulting in polyethylene glycol being unable to better enter the internal adsorption sites. Excessive iron platinum occupies the crystal space of polyethylene glycol, resulting in increased disorder.
[0074] By comparing Comparative Example 1 and Comparative Example 3 (the amount of ferric acetylacetonate is 2.0 g and the amount of chloroplatinic acid hexahydrate is 1.42 g), it can be seen that Comparative Example 3 replaces halloysite (Comparative Example 1) with the modified matrix of the present invention; As a result, the phase change enthalpy of the solid-solid phase change energy storage material obtained in Comparative Example 3 (compared with Comparative Example 1) increases, indicating that when the amount of ferric acetylacetonate is 2.0 g and the amount of chloroplatinic acid hexahydrate is 1.42 g, halloysite is made into the modified matrix of the present invention and used, which is beneficial to increase the phase change enthalpy of the solid-solid phase change energy storage material obtained.
[0075] By comparing Comparative Example 2 and Comparative Example 4 (the amount of ferric acetylacetonate used is 2.16 g and the amount of chloroplatinic acid hexahydrate used is 1.52 g, that is, iron platinum is in excess), it can be seen that in Comparative Example 4, the halloysite (Comparative Example 1) is subjected to methyltrimethoxysilane outer surface hydrophobic modification treatment before use; As a result, the phase change enthalpy of the solid-solid phase change energy storage material obtained in Comparative Example 4 (compared with Comparative Example 2) is reduced, indicating that when iron platinum is in excess, methyltrimethoxysilane outer surface hydrophobic modification treatment of halloysite alone and then used will cause the phase change enthalpy of the solid-solid phase change energy storage material to decrease instead of increase. This is because, if the surface is hydrophobically modified alone, on the one hand, iron platinum will still be excessively deposited and block the lumen and surface pores, resulting in the inability of polyethylene glycol to enter the internal adsorption sites well; on the other hand, methyltrimethoxysilane preferentially reacts with the Si-OH groups on the outer surface of halloysite to form a hydrophobic Si-O-Si(CH3)3 layer. This hydrophobic outer surface layer will further have a negative impact on the surface pore adsorption capacity of halloysite; the superposition of the two negative effects will lead to a decrease in the phase change enthalpy of the prepared solid-solid phase change energy storage material.
[0076] By comparing Comparative Example 2 and Comparative Example 5 (the amount of ferric acetylacetonate is 2.16g and the amount of chloroplatinic acid hexahydrate is 1.52g, that is, the amount of iron platinum is excessive), it can be seen that Comparative Example 5 calcines the halloysite (Comparative Example 1) alone before use; As a result, the phase change enthalpy of the solid-solid phase change energy storage material obtained in Comparative Example 5 (compared to Comparative Example 2) is significantly increased, indicating that when iron platinum is excessive, the phase change enthalpy of the solid-solid phase change energy storage material can be increased by calcining the halloysite alone before use. This is because calcination can remove hydroxyl groups and form a mesoporous structure (pore size expansion), which can not only weaken the degree of lumen blockage caused by excessive iron platinum deposition, but also enhance the embedding ability of polyethylene glycol molecular chains.
[0077] Combined with Example 1 (the amount of ferric acetylacetonate is 2.16 g and the amount of chloroplatinic acid hexahydrate is 1.52 g, that is, iron platinum is in excess), it can be seen that in Example 1, the halloysite is first calcined and then the outer surface is hydrophobically modified with methyltrimethoxysilane before use. As a result, the phase change enthalpy of the solid-solid phase change energy storage material obtained in Example 1 is further increased to 80.9 J / g, indicating that when iron platinum is in excess, the two treatment methods of the matrix material halloysite (calcination treatment and methyltrimethoxysilane outer surface hydrophobic modification treatment) can produce a synergistic effect, synergistically improving the phase change enthalpy of the obtained solid-solid phase change energy storage material.
[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.
[0079] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.
Claims
1. A method for preparing a solid-solid phase change energy storage material, characterized in that: The steps include: S1, adding 2.12-2.18g of ferric acetylacetonate and 7g of the modified substrate to anhydrous ethanol, stirring, adding 1.5-1.54g of chloroplatinic acid hexahydrate in ethanol, stirring under argon atmosphere to obtain a primary solution; S2. Add 11.75-12.35 g of sodium borohydride in ethanol to the primary solution obtained in S1, keep warm in a water bath at 40±2°C for 2 h, wash and dry to obtain a matrix - iron platinum; S3. Adding a polyethylene glycol ethanol solution containing 12.8-13.2 g of polyethylene glycol to the matrix iron platinum obtained in S2, stirring, ultrasonically dispersing, and then heating and stirring in a water bath at a constant temperature of 80±2° C., and then drying to obtain a solid-solid phase change energy storage material; The modified matrix is prepared by calcining halloysite and then subjecting it to hydrophobic treatment with methyltrimethoxysilane.
2. The method for preparing the solid-solid phase change energy storage material according to claim 1, characterized in that: The preparation method of the modified matrix is as follows: A1. In an argon atmosphere, halloysite is placed in a tube furnace, heated to 450-550°C, kept at this temperature for 2-3 hours, and naturally cooled to room temperature to obtain calcined halloysite; A2, adding the calcined halloysite obtained in A1 to anhydrous ethanol and ultrasonically treating the mixture to obtain a halloysite suspension; A3, dissolving methyltrimethoxysilane in anhydrous ethanol to obtain a surface modification solution; A4. Add the surface modification liquid obtained in A3 dropwise to the halloysite suspension obtained in A2, with the mass of methyltrimethoxysilane being 6-8% of the mass of the halloysite. Stir at 48-52°C for 6-6.5 hours, then add deionized water. Centrifuge and wash several times with ethanol, then dry to obtain a modified matrix.
3. The method for preparing the solid-solid phase change energy storage material according to claim 2, characterized in that: In A1, the heating rate is 4-5°C / min.
4. The method for preparing the solid-solid phase change energy storage material according to claim 2, characterized in that: In A2, the mass ratio of the calcined halloysite to anhydrous ethanol is 1:(40-45).
5. The method for preparing the solid-solid phase change energy storage material according to claim 2, characterized in that: In A2, the ultrasonic treatment frequency is 40-50 KHz, and the ultrasonic treatment time is 30-40 min.
6. The method for preparing the solid-solid phase change energy storage material according to claim 2, characterized in that: In A3, the concentration of methyltrimethoxysilane in the surface modification solution is 0.3-0.5 mol / L.
7. The method for preparing the solid-solid phase change energy storage material according to claim 1, characterized in that: In S1, the preparation method of the chloroplatinic acid hexahydrate ethanol solution is as follows: add 1 g of chloroplatinic acid hexahydrate to 95-110 mL of anhydrous ethanol and stir evenly to obtain the solution.
8. The method for preparing the solid-solid phase change energy storage material according to claim 1, characterized in that: In S2, the sodium borohydride ethanol solution is prepared by adding 1 g of sodium borohydride to 250-265 mL of anhydrous ethanol and heating in a 25° C. water bath until dissolved.
9. A solid-solid phase change energy storage material, characterized in that: The method is as described in any one of claims 1 to 8.