Al-based single-layer / double-layer core-shell structure phase change heat storage material and preparation method thereof
By preparing Al-based single-layer/double-layer core-shell structured phase change thermal storage materials, the problem of strong corrosion of molten salt thermal storage materials under high-temperature environments has been solved, providing an efficient and stable thermal energy storage solution suitable for solar thermal power generation systems.
Patent Information
- Application Number
- CN202511183611.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-22
- Publication Date
- 2025-12-05
AI Technical Summary
Existing molten salt thermal storage materials suffer from strong corrosion and poor safety in solar thermal power generation systems, and high-temperature phase change thermal storage materials are insufficient to meet the requirements of CSP systems.
A method for preparing Al-based single-layer/double-layer core-shell structure phase change thermal storage materials is adopted. By forming a Sn(OH)2 shell on the surface of aluminum powder, and then calcining it to form an Al@SnO2 single-shell layer and an Al@SnO2@Al2O3 double-shell layer, a stable encapsulation structure is formed by utilizing the high melting point and catalytic ability of SnO2 and Al2O3.
It achieves high phase change temperature, high latent heat of phase change, and good thermal cycling stability, and can be used in environments of 600 to 1200℃, meeting the industrial needs of solar thermal power plants and reducing equipment corrosion risks and costs.
Smart Images
Figure CN121064797A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of phase change thermal storage composite materials, and in particular to an Al-based single-layer / double-layer core-shell structure phase change thermal storage material and its preparation method. Background Technology
[0002] To better ensure energy security and alleviate the current tense energy situation, it is urgent to promote the transformation of the energy structure and achieve sustainable energy development. Among many renewable energy sources, solar energy has attracted widespread global attention due to its unique advantage of being "inexhaustible".
[0003] In the process of solar energy utilization, concentrated solar power (CSP) can convert solar energy into thermal energy and generate electricity through steam turbines or heat engines. However, the power generation of CSP systems is greatly affected by the instability and intermittency of solar energy and regional climate. Thermal energy storage (TES) systems can store energy for later use, which can make up for the shortcomings of CSP systems. At present, molten salt thermal storage materials are widely used in solar thermal power generation, heating and waste heat recovery due to their advantages such as high energy density, low cost and stable operation. However, current molten salt thermal storage materials still have problems such as strong corrosion and poor safety. Therefore, it is still necessary to develop a new type of thermal storage material that is efficient, sustainable and safe to meet the huge future demand for solar thermal energy storage.
[0004] Core-shell structured phase change thermal energy storage (CSP) materials, as a novel type of thermal energy storage material, can store and release heat at their phase change temperature. This allows for the storage of large amounts of thermal energy within a small volume, resulting in high heat storage density, simple system design, low cost, and high thermal conversion efficiency. It also effectively solves the problems of leakage and corrosion that occur during the phase change process. However, due to the high operating temperature of CSP systems, only high-temperature CSP materials with a phase change temperature above 400℃ can meet the needs of future solar power generation systems.
[0005] Therefore, the development of phase change capsule materials with high phase change temperature, high latent heat of phase change, and high thermal cycling stability has good application prospects in future CSP technology and waste heat recovery. Summary of the Invention
[0006] The purpose of this invention is to provide an Al-based single-layer / double-layer core-shell structured phase change thermal storage material and its preparation method, in order to solve the above-mentioned technical problems.
[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0008] This invention provides a method for preparing Al-based single-layer / double-layer core-shell structured phase change thermal storage materials, comprising the following steps:
[0009] 1) Place the cleaned aluminum powder in a tin salt solution and mix it under heating conditions to form a Sn(OH)2 shell on the surface of the aluminum powder particles, which serves as a precursor.
[0010] 2) The precursor was calcined in air and cooled to obtain Al@SnO2 single-shell phase change heat storage material;
[0011] 3) The precursors in step 1) are sequentially subjected to low-temperature calcination and high-temperature calcination to obtain Al@SnO2@Al2O3 double-shell core-shell phase change heat storage material;
[0012] The Al-based single-layer / double-layer core-shell structure phase change thermal storage materials include Al@SnO2 single-shell and Al@SnO2@Al2O3 double-shell core-shell structure phase change thermal storage materials.
[0013] Furthermore, in step 1), the heating conditions are 20–110°C; the concentration of the tin salt solution is 0.01–0.5 mol / L, and the tin salt contains one or more of SnCl2, SnSO4, and Sn(NO3)4.
[0014] Furthermore, in step 1), the mixing method includes water bath, magnetic stirring, or ultrasonic mixing.
[0015] Furthermore, in step 2), the calcination temperature is 200–600°C, the heating rate is 2–20°C / min, and the calcination time is 1–4 hours.
[0016] Furthermore, in step 3), the low-temperature calcination temperature is 200–600°C, the heating rate is 2–20°C / min, and the time is 1–4h.
[0017] Furthermore, in step 3), the high-temperature calcination temperature is 700–800°C, the heating rate is 2–20°C / min, and the time is 1–4 hours.
[0018] The present invention also provides an Al-based single-layer / double-layer core-shell structured phase change thermal storage material.
[0019] The beneficial effects of this invention are:
[0020] 1. This invention selects aluminum powder as the core of the composite thermal storage material. Aluminum has a phase transition temperature of 660℃. When tin dioxide is used as the encapsulation shell, its melting point is 1630℃ and its boiling point is 1800℃; when alumina is used as the encapsulation shell, its melting point is 2054℃ and its boiling point is 2980℃. When aluminum undergoes a phase transition, the single-shell Al@SnO2 and double-shell Al@SnO2@Al2O3 core-shell structures can maintain good physical properties and stable encapsulation structure and performance. This material can be used in high-temperature environments of 600–1200℃, making it easier to meet the industrial needs of solar thermal power plants.
[0021] 2. This invention utilizes the characteristic that oxygen vacancies and defect sites on the surface of SnO2 can adsorb and activate oxygen molecules to promote the formation of Al2O3 during high-temperature thermal oxidation treatment, and prepares Al@SnO2@Al2O3 core-shell structure phase change heat storage material, which effectively reduces the thermal oxidation temperature required for Al2O3 formation and improves the thermal cycling stability of the material.
[0022] 3. The composite phase change thermal storage material prepared by this invention uses aluminum as the core material, which has a higher latent heat of phase change (about 345 J / g) than traditional molten salt thermal storage materials (about 70-300 J / g), and better thermal stability, making it more suitable for industrial applications in the field of high-temperature thermal storage.
[0023] 4. The core-shell structure prepared by this invention is tightly encapsulated, which can effectively prevent the leakage of heat storage materials from causing corrosion to the metal container, and significantly reduce equipment costs;
[0024] 5. The raw materials used in this invention are inexpensive, the preparation process is simple, the parameters are more controllable, and it is easier to achieve large-scale industrial production. Attached Figure Description
[0025] Figure 1 XRD patterns of Al@SnO2 core-shell composite phase change thermal storage materials prepared in Examples 3(a) and 6(b) of this invention;
[0026] Figure 2 This is a SEM image of the Al@SnO2 core-shell composite phase change thermal storage material prepared in Example 2 of this invention.
[0027] Figure 3 This is a SEM image of the Al@SnO2 core-shell composite phase change thermal storage material prepared in Example 3 of this invention;
[0028] Figure 4 The image shows the XRD pattern of the Al@SnO2@Al2O3 core-shell composite phase change thermal storage material prepared in Example 5 of this invention.
[0029] Figure 5This is a SEM image of the Al@SnO2@Al2O3 core-shell composite phase change thermal storage material prepared at 800℃ in Example 7 of the present invention. Detailed Implementation
[0030] This invention provides a method for preparing Al-based single-layer / double-layer core-shell structured phase change thermal storage materials, comprising the following steps:
[0031] 1) Place the cleaned aluminum powder in a tin salt solution and mix it under heating conditions to form a Sn(OH)2 shell on the surface of the aluminum powder particles, which serves as a precursor.
[0032] 2) The precursor was calcined in air and cooled to obtain Al@SnO2 single-shell phase change heat storage material;
[0033] 3) The precursors in step 1) are sequentially subjected to low-temperature calcination and high-temperature calcination to obtain Al@SnO2@Al2O3 double-shell core-shell phase change heat storage material;
[0034] The Al-based single-layer / double-layer core-shell structure phase change thermal storage materials include Al@SnO2 single-shell and Al@SnO2@Al2O3 double-shell core-shell structure phase change thermal storage materials.
[0035] In this invention, aluminum powder is first placed in water and ultrasonically cleaned, and then placed in a drying oven at 80°C for 1 hour to obtain cleaned aluminum powder.
[0036] In this invention, in step 1), the heating condition is 20–110°C; the concentration of the tin salt solution is 0.01–0.5 mol / L, preferably 0.01 mol / L, 0.03 mol / L, 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, or 0.5 mol / L.
[0037] Tin salts include one or more of SnCl2, SnSO4 and Sn(NO3)4, preferably SnCl2 and / or SnSO4.
[0038] In this invention, the mixing method in step 1) includes water bath, magnetic stirring or ultrasonic waves, preferably magnetic stirring.
[0039] In this invention, in step 2), the calcination temperature is 200-600℃, preferably 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, or 600℃; the heating rate is 2-20℃ / min, preferably 2℃ / min, 5℃ / min, 10℃ / min, or 20℃ / min; and the calcination time is 1-4h, preferably 1h, 2h, 3h, or 4h.
[0040] In this invention, step 2) is to convert Sn(OH)2 into SnO2 and coat it onto the Al surface to form an Al@SnO2 core-shell structure.
[0041] In this invention, in step 3), the low-temperature calcination temperature is 200-600℃, preferably 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, or 600℃; the heating rate is 2-20℃ / min, preferably 2℃ / min, 5℃ / min, 10℃ / min, or 20℃ / min; and the time is 1-4h, preferably 1h, 2h, 3h, or 4h.
[0042] In this invention, the purpose of low-temperature calcination is to convert Sn(OH)2 into SnO2 and coat it onto the Al surface.
[0043] In this invention, in step 3), the high-temperature calcination temperature is 700-800℃, preferably 700℃, 750℃, or 800℃; the heating rate is 2-20℃ / min, preferably 2℃ / min, 5℃ / min, 10℃ / min, or 20℃ / min; and the time is 1-4h, preferably 1h, 2h, 3h, or 4h.
[0044] In this invention, the high-temperature calcination is used to utilize the excellent catalytic ability and strong oxygen exchange capacity of SnO2 to reduce the thermal oxidation temperature required for the formation of Al2O3, and finally form the Al@SnO2@Al2O3 core-shell structure at a lower thermal oxidation temperature.
[0045] The present invention also provides an Al-based single-layer / double-layer core-shell structured phase change thermal storage material.
[0046] This invention proposes a method for preparing Al-based core-shell composite phase change thermal storage materials. First, a precursor for the Al-based core-shell composite phase change thermal storage material is prepared through pretreatment under different operating conditions. During the preparation process, parameters such as heating temperature and heating method are adjusted to form a stable Sn(OH)2 shell on the surface of aluminum particles. Then, thermal oxidation treatment is performed to prepare Al-based core-shell composite phase change thermal storage materials Al@SnO2 / Al@SnO2@Al2O3. During the calcination process, parameters such as calcination temperature and calcination time are adjusted to obtain highly stable and high thermal storage single-shell Al@SnO2 and double-shell Al@SnO2@Al2O3 core-shell structures.
[0047] SnO2 and Al2O3 were selected as the encapsulation materials for the aluminum core of the phase change material. Tin dioxide, when used as the encapsulation shell, has a melting point of 1630℃ and a boiling point of 1800℃. Furthermore, due to its excellent catalytic and oxygen exchange capabilities, it can effectively promote the formation of the Al2O3 shell. Aluminum oxide, when used as the encapsulation shell, has a melting point of 2054℃ and a boiling point of 2980℃. When aluminum undergoes a phase change, both single-shell Al@SnO2 and double-shell Al@SnO2@Al2O3 core-shell structures can maintain good physical properties and stable encapsulation structure and performance.
[0048] The technical solutions provided by the present invention will be 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.
[0049] Example 1
[0050] A method for preparing an Al monolayer / core-shell structured composite phase change thermal storage material includes the following steps:
[0051] (1) Preparation of precursors for Al@Sn(OH)2 core-shell structured composite phase change thermal storage materials:
[0052] Take 12g of aluminum powder and add it to 200mL of deionized water for ultrasonic oscillation and cleaning at 70W for 10min; dry the obtained sample at 80℃ for 1h to obtain aluminum powder; prepare a 0.3mol / L SnCl2 solution; adjust the pH of the above solution to 7.5 to form Sn(OH)2 precipitate;
[0053] (2) Add the aluminum powder sample to the SnCl2 solution obtained above and perform magnetic stirring at 30°C for 4 hours; then let the obtained sample stand for 12 hours and dry it at 100°C for 12 hours.
[0054] (3) Preparation of Al@SnO2 single-shell phase change thermal storage material:
[0055] 2g of the above sample was heated at a constant rate to 350℃ and subjected to thermal oxidation treatment for 4h to obtain core-shell structured Al@SnO2, wherein the constant rate of heating was 10℃ / min, and Al@SnO2 single-shell phase change thermal storage material was obtained.
[0056] (4) Preparation of Al@SnO2@Al2O3 core-shell structured composite phase change thermal storage material:
[0057] 2g of Al@SnO2 single-shell phase change thermal storage material was uniformly heated to 350℃ and held at that temperature for 4h to convert Sn(OH)2 into SnO2, which then coated the Al surface. After that, the temperature was uniformly heated again to 750℃ and held at that temperature for 2h. The core-shell structure Al@SnO2@Al2O3 was obtained by uniformly heating at a rate of 10℃ / min.
[0058] Example 2
[0059] Same as Example 1, except that the concentrations of the SnCl2 solutions are 0.03 mol / L, 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, and 0.5 mol / L, respectively, while the other parameters remain unchanged.
[0060] Example 3
[0061] Same as Example 1, except that the calcination temperatures in step (3) are 350°C, 450°C and 550°C respectively, while the other parameters remain unchanged.
[0062] Example 4
[0063] Same as Example 1, except that the low-temperature calcination temperatures in step (4) are 250℃, 300℃, 400℃, 450℃, 500℃, 550℃ and 600℃ respectively, while the other parameters remain unchanged.
[0064] Example 5
[0065] Same as Example 1, except that the high-temperature roasting temperatures in step (4) are 750°C and 800°C respectively, while the other parameters remain unchanged.
[0066] Example 6
[0067] Same as Example 1, except that in step (2), the obtained aluminum powder sample is placed in a constant temperature water bath and magnetically stirred at a constant temperature of 50°C for 1 hour to form a Sn(OH)2 shell on the surface of the aluminum particles, while the other parameters remain unchanged.
[0068] Example 7
[0069] Same as Example 6, except that the high-temperature roasting temperatures in step (4) are 750°C and 800°C respectively, while the other parameters remain unchanged.
[0070] Figure 1 The images show the XRD patterns of the Al@SnO2 core-shell composite phase change thermal storage materials prepared in Examples 3(a) and 6(b) of this invention. As can be seen from the images, the main components of the samples are Al and SnO2. Figure 2The images show SEM images of the Al@SnO2 core-shell composite phase change thermal energy storage material prepared in Example 2 of this invention. (a), (b), (c), and (d) represent SEM images of samples prepared when the SnCl2 solution concentrations are 0.03 mol / L, 0.1 mol / L, 0.2 mol / L, and 0.3 mol / L, respectively. As can be seen from the images, as the SnCl2 solution concentration increases, the SnO2 formed on the surface of the Al microspheres becomes more dense and uniform.
[0071] Figure 3 The image shows a SEM image of the Al@SnO2 core-shell composite phase change thermal storage material prepared in Example 3 of this invention. As can be seen from the image, the surface of the Al microspheres is successfully covered with uniform and dense SnO2.
[0072] Figure 4 The XRD patterns of the Al@SnO2@Al2O3 core-shell composite phase change thermal storage material prepared in Example 5 of this invention are shown in (a) and (b), which represent the XRD patterns of the samples at high-temperature thermal oxidation temperatures of 750℃ and 800℃, respectively. It can be seen from the figures that the main components of the sample after thermal oxidation at 750℃ are Al and SnO2, while the main components of the sample after thermal oxidation at 800℃ are Al, SnO2 and Al2O3.
[0073] Figure 5 The image shows a SEM image of the Al@SnO2@Al2O3 core-shell composite phase change thermal storage material prepared in Example 7 of this invention. It can be seen from the image that a double-shell structure was successfully formed on the surface of the Al microspheres.
[0074] Table 1. Latent heat value of Al@SnO2 core-shell structured composite phase change thermal storage material
[0075] Sample Name Enthalpy of fusion (J / g) Enthalpy of crystallization (J / g) 30-4-350-4 219.2 217.1 30-4-450-4 232.5 232.1 30-4-550-4 220.1 230.0 50-4-550-4 205.7 215.8
[0076] Table 2. Latent heat values of Al@SnO2@Al2O3 core-shell structured composite phase change thermal storage materials
[0077] Sample Name Enthalpy of fusion (J / g) Enthalpy of crystallization (J / g) 30-4-350-4-800-2 151.1 156.6 30-4-450-4-800-2 135.6 141.8 30-4-550-4-800-2 150.4 166.5 50-4-550-4-800-2 160.1 162.8
[0078] The "30-4-350-4" indicates that the magnetic stirring is performed at 30℃ for 4 hours, followed by thermal oxidation treatment at 350℃ for 4 hours.
[0079] "30-4-350-4-800-2" means: magnetic stirring at 30℃ for 4 hours, thermal oxidation treatment at 350℃ for 4 hours, and thermal oxidation treatment at 800℃ for 2 hours.
[0080] Tables 1 and 2 show the latent heat values of Al@SnO2 and Al@SnO2@Al2O3 core-shell composite phase change heat storage materials, respectively. As can be seen from the tables, the sample prepared under the conditions of magnetic treatment temperature of 50℃ and low-temperature thermal oxidation temperature of 550℃ has a more stable structure. Specifically, the latent heat value of the sample after high-temperature thermal oxidation treatment at 800℃ is higher.
[0081] As shown in the above embodiments, this invention provides an Al-based single-layer / double-layer core-shell structure phase change thermal storage material and its preparation method. This invention produces a composite phase change thermal storage material with high temperature resistance, corrosion resistance, excellent microstructure, strong thermal storage capacity, excellent thermal cycling stability, and a low thermal oxidation temperature required to form the core-shell structure. This invention selects aluminum powder as the core of the composite thermal storage material. The phase change temperature of aluminum is 660℃. When tin dioxide is used as the encapsulation shell, its melting point is 1630℃ and its boiling point is 1800℃; when alumina is used as the encapsulation shell, its melting point is 2054℃ and its boiling point is 2980℃. When aluminum undergoes a phase change, the single-shell Al@SnO2 and double-shell Al@SnO2@Al2O3 core-shell structures can maintain good physical properties and stable encapsulation structure and performance. This material can be used in high-temperature environments of 600–1200℃, making it easier to meet the industrial needs of solar thermal power plants.
[0082] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing an Al-based single / double-layer core-shell structure phase change heat storage material, characterized in that, The method comprises the following steps: 1) placing the cleaned aluminum powder into a tin salt solution, mixing under heating conditions to form a Sn(OH)2 shell on the surface of the aluminum powder particles as a precursor; 2) calcining the precursor in an air atmosphere to obtain an Al@SnO2 single-shell phase change heat storage material after cooling; 3) sequentially performing low-temperature calcination and high-temperature calcination on the precursor in step 1) to obtain an Al@SnO2@Al2O3 double-shell core-shell phase change heat storage material; The Al-based single / double-layer core-shell structure phase change heat storage material comprises an Al@SnO2 single-shell and an Al@SnO2@Al2O3 double-shell core-shell structure phase change heat storage material.
2. The preparation method of Al-based single-layer / double-layer core-shell structure phase change thermal storage material according to claim 1, characterized in that, In step 1), the heating condition is 20-110 ℃; the concentration of the tin salt solution is 0.01-0.5 mol / L, and the tin salt comprises one or more of SnCl2, SnSO4 and Sn(NO3)4.
3. The method for preparing Al-based single-layer / double-layer core-shell structure phase change thermal storage material according to claim 2, characterized in that, In step 1), the mixing mode comprises water bath, magnetic stirring or ultrasonic wave.
4. The method for preparing Al-based single / double-layered core-shell structure phase change heat storage material according to any one of claims 1 to 3, characterized in that, In step 2), the calcination temperature is 200-600 ℃, the temperature rising rate is 2-20 ℃ / min, and the calcination time is 1-4 h.
5. The method for preparing Al-based single-layer / double-layer core-shell structure phase change thermal storage material according to claim 4, characterized in that, In step 3), the low-temperature calcination temperature is 200-600 ℃, the temperature rising rate is 2-20 ℃ / min, and the time is 1-4 h.
6. The method for preparing Al-based single-layer / double-layer core-shell structure phase change thermal storage material according to claim 1 or 5, characterized in that, In step 3), the high-temperature calcination temperature is 700-800 ℃, the temperature rising rate is 2-20 ℃ / min, and the time is 1-4 h.
7. The Al-based single / double-layer core-shell structure phase change heat storage material prepared by the preparation method in any one of claims 1-6.