Phase change energy storage composite material and preparation method and application thereof
By adding nucleating agents and modifiers to sodium acetate trihydrate, a phase change energy storage composite material was prepared, which solved the problems of supercooling and loss of crystal water, and improved the energy storage performance and application range of the material.
Patent Information
- Application Number
- CN202511603269.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-04
- Publication Date
- 2026-01-23
AI Technical Summary
Sodium acetate trihydrate suffers from severe supercooling, insufficient crystallization kinetics, and loss of crystal water in practical applications, leading to a decline in energy storage performance and making it difficult to meet the temperature control requirements in fields such as industrial waste heat recovery and building heating.
Phase change energy storage composite materials were prepared by adding di or trihydrated hydrogen phosphate as nucleating agents, biopolysaccharides or plant extract gums as modifiers, lattice structure regulators and graphite, etc., to improve supercooling and crystallization characteristics and adjust phase change temperature.
It achieves lower supercooling and better crystallization characteristics, improving the practicality and long-term cycling stability of the material and expanding its application range.
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Figure CN121379535A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of energy storage, in particular to a phase change energy storage composite material and a preparation method and application thereof. BACKGROUND
[0002] With the increasing urgency of global energy structure adjustment and energy saving and emission reduction demand, the application value of phase change energy storage technology in the field of building energy saving and renewable energy utilization is increasingly prominent. As a typical low-temperature phase change material (PCM), hydrated salt has unique thermal management characteristics due to the reversible crystal water combined in its crystal structure. This kind of material realizes heat storage and release through the solid-liquid phase change process of "hydration-dehydration", and its phase change enthalpy value is significantly higher than that of traditional paraffin organic materials (up to 200-300 J / g), and it has the advantages of easy availability of raw materials, low cost (about 1 / 5 of organic PCM), environmental friendliness and other outstanding advantages.
[0003] In terms of specific application, different hydrated salt systems are suitable for multi-scene thermal management according to their phase change temperature differences: the phase change temperature of sodium acetate trihydrate (CH3COONa·3H2O) is about 58℃, which is suitable for solar heat collection system; sodium carbonate decahydrate (Na2CO3·10H2O) is suitable for building wall temperature regulation in the phase change interval of 32-36℃; and sodium phosphate dibasic dodecahydrate (Na2HPO4·12H2O) is suitable for electronic equipment cooling in the working range of 35-40℃. These materials realize heat storage and release through reversible crystal water de-embedding reaction, and its basic chemical equation can be expressed as: Salt·nH2O ⇌ Salt+nH2O-ΔH.
[0004] Among them, sodium acetate trihydrate as a phase change energy storage material is concerned due to its suitable phase change temperature (about 58℃), high latent heat of phase change (about 250J / g) and significant cost-effectiveness. However, there are several technical bottlenecks in the actual application process of the material: firstly, although the thermodynamic equilibrium freezing temperature of sodium acetate trihydrate is 58℃, in actual working conditions, liquid sodium acetate trihydrate often needs to be cooled to below 20℃ or even lower temperature range to realize spontaneous solidification, and the supercooling degree can exceed 30℃. This significant supercooling phenomenon makes the material unable to release the latent heat of phase change in the target temperature zone (about 58℃) in time, resulting in the functional failure of the energy storage system, which is difficult to meet the requirements of temperature control accuracy in the fields of industrial waste heat recovery, building heating and the like. Even if the supercooling phenomenon is inhibited by adding nucleating agents, the material still faces the problem of insufficient crystallization kinetics, which is specifically manifested in slow crystallization rate, incomplete crystallinity and crystal agglomeration and the like. More prominently, sodium acetate trihydrate will appear irreversible degradation phenomena such as phase separation and loss of crystallization water after multiple phase change cycles, thereby leading to a continuous attenuation trend of its energy storage performance. These inherent defects seriously restrict the practical application value of the material under long-term cyclic working conditions.
[0005] In view of this, the present application is proposed. SUMMARY
[0006] The present application aims to provide a phase change energy storage composite material and a preparation method and application thereof, so as to improve the above technical problems.
[0007] The present application is implemented as follows: In a first aspect, the present application provides a phase change energy storage composite material, which comprises, by mass percentage, 90% to 99% of a main phase change material, 1% to 3% of a nucleating agent, 0.15% to 4% of a modifier, 0% to 5.5% of a crystal lattice structure adjusting agent and 0% to 2% of graphite. Among them, the main phase change material is sodium acetate trihydrate, the nucleating agent is diphosphonium hydrogen phosphate dodecahydrate or trihydrate salt, and the modifier is selected from one or more of biological polysaccharides, plant extract glue and sodium polyacrylate.
[0008] In an optional embodiment, the diphosphonium hydrogen phosphate dodecahydrate comprises one or more of diphosphonium hydrogen sodium dodecahydrate, diphosphonium hydrogen potassium dodecahydrate and trisodium phosphate dodecahydrate. And / or, the trihydrate salt is one or more of sodium formate trihydrate and potassium acetate trihydrate.
[0009] In an optional embodiment, the biological polysaccharide comprises one or more of xanthan gum, gellan gum and welan gum. The plant extract glue comprises one or more of guar gum, locust bean gum and carrageenan.
[0010] In an optional embodiment, the crystal lattice structure regulator comprises one or more of potassium chloride, sodium chloride, ammonium chloride, and potassium sulfate.
[0011] In an optional embodiment, the graphite comprises one or more of expanded graphite worm and hydrophilic spherical graphite.
[0012] In a second aspect, the present application provides a preparation method of the phase change energy storage composite material according to any one of the preceding embodiments, which comprises: after the main phase change material is heated and melted, the cold uniform mixture of the remaining components is fully mixed with the main phase change material in a molten state, and then cooled and solidified.
[0013] In an optional embodiment, the fully mixing of the cold uniform mixture of the remaining components with the main phase change material in a molten state is to add the cold uniform mixture into the main phase change material in a molten state under stirring, and to maintain the main phase change material in a molten state and continue stirring.
[0014] In an optional embodiment, the temperature of the heating source for heating the main phase change material is controlled to be 70-80℃.
[0015] In an optional embodiment, the stirring speed is greater than 500 rpm.
[0016] In a third aspect, the present application provides an application of the phase change energy storage composite material according to any one of the preceding embodiments in solar heat storage or electronic device thermal management.
[0017] The present application has the following beneficial effects: through the synergistic effect of the components, the phase change energy storage material has a lower supercooling degree and good crystallization characteristics, thereby greatly improving the practicability of the material. In addition, the melting point of the material can be adjusted by the crystal lattice structure regulator, thereby realizing the adjustment of the main phase change point and expanding the application range of the material. BRIEF DESCRIPTION OF DRAWINGS
[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.
[0019] Figure 1 The temperature rise and fall step cooling curve diagram of the phase change energy storage composite material of the present application embodiment 1; Figure 2 The temperature rise and fall step cooling curve diagram of the phase change energy storage composite material of the present application embodiment 2; Figure 3 The heating and cooling step cooling curve diagram of the phase change energy storage composite material of Example 3 of the present application; Figure 4 The heating and cooling step cooling curve diagram of the phase change energy storage composite material of Example 4 of the present application; Figure 5 The heating and cooling step cooling curve diagram of sodium acetate trihydrate of Comparative Example 1 of the present application; Figure 6 The heating and cooling step cooling curve diagram of the phase change energy storage composite material of Comparative Example 2 of the present application; Figure 7 The heating and cooling step cooling curve diagram of the phase change energy storage composite material of Comparative Example 3 of the present application; Figure 8 The heating and cooling step cooling curve diagram of the phase change energy storage composite material of Comparative Example 4 of the present application; Figure 9 The heating and cooling step cooling curve diagram of the phase change energy storage composite material of Comparative Example 5 of the present application; Figure 10 The long-term cycle enthalpy value change diagram of the phase change material of the phase change energy storage composite material of Examples 1-3 of the present application at different temperature points. DETAILED DESCRIPTION
[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be clearly and completely described below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.
[0021] The phase change energy storage composite material provided by the present application, and the preparation method and application thereof will be specifically described below.
[0022] Based on the problems of sodium acetate trihydrate, such as serious supercooling phenomenon, phase separation and dehydration, and poor crystallization characteristics, the inventors modified sodium acetate trihydrate through a large amount of practice and research, constructed a composite material, so as to improve the above technical problems.
[0023] Some embodiments of the present application provide a phase change energy storage composite material, which comprises 90%-99% of a main phase change material, 1%-3% of a nucleating agent, 0.15%-4% of a modifier, 0%-5.5% of a crystal lattice structure adjusting agent, and 0%-2% of graphite, in terms of mass percentage.
[0024] For reference, the mass percentage of the host phase change material in the phase change energy storage composite material can be selected as 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99%, or between any two of the above mass percentages; the mass percentage of the nucleating agent in the phase change energy storage composite material can be selected as 1%, 1.5%, 2%, 2.5% or 3%, or between any two of the above mass percentages; the mass percentage of the modifier in the phase change energy storage composite material can be selected as 0.15%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5% or 4%, or between any two of the above mass percentages; the mass percentage of the crystal lattice structure regulator in the phase change energy storage composite material can be selected as 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, or between any two of the above mass percentages; the mass percentage of the graphite in the phase change energy storage composite material can be selected as 0%, 1%, 1.5% or 2%, or between any two of the above mass percentages.
[0025] The host phase change material is sodium acetate trihydrate, which is mainly an analytically pure, industrial grade qualified product or above, to ensure that it has good phase change energy storage performance.
[0026] The nucleating agent is diphosphoric acid hydrogen di-salt dodecahydrate or trihydrate salt. For example, the diphosphoric acid hydrogen di-salt dodecahydrate includes but is not limited to one or more of sodium diphosphate dodecahydrate, potassium diphosphate dodecahydrate and sodium triphosphate dodecahydrate; the trihydrate salt includes but is not limited to one or more of sodium formate trihydrate and potassium acetate trihydrate.
[0027] By selecting the diphosphoric acid hydrogen di-salt dodecahydrate or trihydrate salt as the nucleating agent, it can effectively provide heterogeneous nucleation points for sodium acetate trihydrate, reduce the nucleation energy barrier, and thus reduce the supercooling degree.
[0028] The modifier is selected from one or more of biological polysaccharides, plant extract glue and sodium polyacrylate. For example, the biological polysaccharides include but are not limited to one or more of xanthan gum, gellan gum and welan gum; the plant extract glue includes but is not limited to one or more of guar gum, locust bean gum and carrageenan. For example, the CAS number of sodium polyacrylate is 9003-04-7.
[0029] By selecting the above specific modifier, the viscosity of the phase change system can be effectively improved, the component stratification caused by fluid convection can be slowed down, and the phase separation can be inhibited; at the same time, the molecular structure can form a stable hydration system with water, which can assist in reducing the loss of crystal water and enhancing the stability of the system.
[0030] Further, in some embodiments, the lattice structure regulator includes, but is not limited to, one or more of potassium chloride, sodium chloride, ammonium chloride, and potassium sulfate. By adding the lattice structure regulator, the lattice parameter can be changed, the intermolecular force of sodium acetate trihydrate is affected, the melting point of the host material is affected, the phase change temperature of the composite material is adjusted, and the application range of the material is expanded.
[0031] Further, in some embodiments, the graphite includes, but is not limited to, one or more of expanded graphite worms and hydrophilic spherical graphite. By adding a specific graphite, a continuous or semi-continuous heat transfer network can be formed in the sodium acetate trihydrate system, the thermal conduction resistance is reduced, the heat transfer in the material is accelerated, and the heat absorption efficiency in the energy storage stage and the heat release response speed in the energy release stage are improved.
[0032] Some embodiments of the present application also provide a preparation method of the phase change energy storage composite material as described in any one of the preceding embodiments, which includes: heating and melting the host phase change material, and then mixing a cold uniform mixture of the remaining components with the host phase change material in a molten state.
[0033] Specifically, in some embodiments, the preparation method includes the following steps: S1, heating and melting sodium acetate trihydrate.
[0034] The host phase change material sodium acetate trihydrate is heated and melted in a water bath, and the temperature of the water bath can be set to 70-80°C. For example, it can be set to 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, or 80°C.
[0035] S2, mixing a cold uniform mixture of the remaining components with the host phase change material in a molten state.
[0036] Specifically, the cold uniform mixture is added to the host phase change material in a molten state under stirring, and the host phase change material is maintained in a molten state, and stirring is continued. It should be noted that the host phase change material is maintained in a molten state, that is, the temperature of the heating source is controlled to be stable at 70-80°C.
[0037] The host phase change material is heated first. On the one hand, it avoids uneven dispersion caused by inter-particle friction and agglomeration force when directly mixed with other materials. On the other hand, the molten PCM provides a stable mixing environment, facilitates accurate addition of each component according to the design ratio, and controls the dispersion effect through stirring speed and temperature adjustment.
[0038] In some embodiments, in order to achieve a better uniform dispersion effect, the stirring speed is greater than 500 rpm.
[0039] Some embodiments of the present application also provide the application of the phase change energy storage composite material in any of the preceding embodiments in solar heat storage or electronic device thermal management.
[0040] The phase change parameters of the phase change energy storage composite material are accurately matched, and the material has the core advantages of excellent heat conduction performance, low cost and high safety, and has irreplaceable application value in the fields of low-grade solar heat storage (such as building heating, solar water heating system) and medium-low temperature electronic device thermal management (such as consumer electronics, server cooling).
[0041] The features and performance of the present application are further described in detail below in conjunction with the embodiments.
[0042] Example 1 The present embodiment provides a preparation method of a phase change energy storage composite material, which specifically comprises the following steps: 49g of sodium acetate trihydrate was heated and melted in a water bath, and the heating water temperature was set to 75℃. 0.5g of analytical grade sodium formate trihydrate, 0.1g of analytical grade sodium polyacrylate, and 1g of expanded graphite worm were mixed uniformly and then added to the stirring sodium acetate trihydrate, while mechanical stirring was continued for half an hour at a stirring speed of 1000 revolutions / min. Then, the container containing the composite phase change material was placed in the air for further stirring and cooling to form a shape.
[0043] The material temperature-time curve (horizontal coordinate: time; vertical coordinate: material temperature) is shown in Figure 1 The phase change temperature is 57-58℃.
[0044] Example 2 The present embodiment provides a preparation method of a phase change energy storage composite material, which specifically comprises the following steps: 50g of sodium acetate trihydrate was heated and melted in a water bath, and the heating water temperature was set to 79℃. 1.5g of sodium phosphate dibasic dodecahydrate, 0.7g of xanthan gum, 0.3g of locust bean gum, and 3g of hydrophilic spherical graphite were mixed uniformly and then added to the stirring sodium acetate trihydrate, while mechanical stirring was continued for half an hour at a stirring speed of 1000 revolutions / min. Then, the container containing the composite phase change material was placed in the air for further stirring and cooling to form a shape.
[0045] The material temperature-time curve (horizontal coordinate: time; vertical coordinate: material temperature) is shown in Figure 2 The phase change temperature is 55℃.
[0046] Example 3 The present embodiment provides a preparation method of a phase change energy storage composite material, which specifically comprises the following steps: 50g sodium acetate trihydrate was heated and melted in a water bath, the water temperature was set to 79℃. 1.0g dodecahydrate potassium phosphate dibasic, 1.3g gellan gum, 3g potassium chloride were mixed uniformly and added to the sodium acetate trihydrate, and mechanical stirring was continued for half an hour at a stirring speed of 800r / min. Then the container containing the composite phase change material was placed in the air and continued to be stirred and cooled to form.
[0047] The material temperature rise and fall step cooling curve (horizontal coordinate is time, vertical coordinate is material temperature) is shown in Figure 3 , and the phase change temperature is 50℃.
[0048] Example 4 The difference between this example and Example 1 is that 0.5g of analytical grade sodium formate trihydrate, 1g of xanthan gum, 3g of potassium chloride, and 1g of expanded graphite worm are mixed uniformly and added to the stirring sodium acetate trihydrate. Its step cooling curve Figure 4 It can be seen that the cooling platform temperature has dropped to about 50℃.
[0049] Comparative Example 1 This comparative example provides sodium acetate trihydrate without any modification. The material temperature rise and fall step cooling curve (horizontal coordinate is time, vertical coordinate is material temperature) is shown in Figure 5 , and the material cannot crystallize.
[0050] Comparative Example 2 This comparative example provides a preparation method of a phase change energy storage composite material, which is different from Example 1 only in that starch is used instead of polyacrylic acid sodium in Example 1. Since starch is prone to degradation under long-term high and low temperature cycles in the sodium acetate trihydrate system, the phase separation of the system is intensified, and eventually the heat storage capacity of the material system is lost (the step cooling curve is shown in Figure 6 ).
[0051] Comparative Example 3 This comparative example provides a preparation method of a phase change energy storage composite material, which is different from Example 1 only in that carboxymethyl cellulose (CMC) is used instead of polyacrylic acid sodium in Example 1. Its step cooling curve cycle is shown in Figure 7 It can be seen that as the number of cycles increases, the cooling platform time is gradually shortened, indicating that the system material has phase separation and poor long-term cycle stability.
[0052] Comparative Example 4 This comparative example provides a preparation method of a phase change energy storage composite material, which is different from Example 1 only in that barium hydroxide octahydrate is used instead of sodium formate trihydrate. Its step cooling curve is shown in Figure 8As shown, it can be seen that with the increase of the cycle number, the material crystallization characteristics appear to decline, gradually increasing the supercooling degree.
[0053] Comparative Example 5 The present comparative example provides a preparation method of a phase change energy storage composite material, which is compared with Example 2, and the difference is only that the addition amount of hydrophilic spherical graphite is 9g hydrophilic spherical graphite, and the cycle step cooling curve is as shown in the following figure: Figure 9 As shown, supercooling and crystallization characteristics appear to decline.
[0054] The long-term cycle enthalpy value changes of the phase change energy storage composite materials of Examples 1-3 at different temperature points are as shown in the following figure (the horizontal coordinate is the cycle number, and the vertical coordinate is the phase change enthalpy Kj / kg): Figure 10 As shown, the red dot represents the phase change energy storage composite material of Example 3 with a phase change temperature of about 50℃, the blue dot represents the phase change energy storage composite material of Example 1 with a phase change of 57-58℃, and the other represents the phase change energy storage composite material of Example 2 with a phase change of 55℃. From the results of Figure 10 It can be known from the results that the phase change energy storage composite material of the present example has better cycle stability.
[0055] In summary, the phase change energy storage composite material obtained by the present example has lower supercooling degree and good crystallization characteristics, and the practicability of the material is improved. In addition, the present example can also realize the adjustment and control of the main phase change point by adjusting the melting point of the material, thereby expanding the application range of the material.
[0056] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A phase change energy storage composite material, characterized in that, by mass percentage, it includes 90%~99% of the main phase change material, 1%~3% of the nucleating agent, 0.15%~4% of the modifier, 0%~5.5% of the crystal lattice structure regulator and 0%~2% of the graphite; Wherein, the main phase change material is sodium acetate trihydrate, the nucleating agent is diphosphoric acid hydrogen di-salt or tri-salt, and the modifier is selected from one or more of biological polysaccharides, plant extract glue and sodium polyacrylate.
2. The phase change energy storage composite of claim 1, wherein, The diphosphoric acid hydrogen di-salt includes one or more of diphosphoric acid hydrogen di-sodium, diphosphoric acid hydrogen di-potassium and tri-sodium phosphate. And / or, the tri-salt includes one or more of sodium formate trihydrate and potassium acetate trihydrate.
3. The phase change energy storage composite of claim 1, wherein, The biological polysaccharides include one or more of xanthan gum, gellan gum and welan gum. The plant extract glue includes one or more of guar gum, locust bean gum and carrageenan.
4. The phase change energy storage composite material according to any one of claims 1-3, characterized in that, The crystal lattice structure regulator includes one or more of potassium chloride, sodium chloride, ammonium chloride and potassium sulfate.
5. The phase change energy storage composite material according to any one of claims 1-3, characterized in that, The graphite includes one or more of expanded graphite worm and hydrophilic spherical graphite.
6. A method of producing a phase change energy storage composite material according to any one of claims 1 to 5, characterized by, It includes: After the main phase change material is heated and melted, the cold uniform mixture of the remaining components is fully mixed with the main phase change material in a molten state, and then cooled and solidified.
7. The method of claim 6, wherein the phase change energy storage composite is prepared by a process comprising: Fully mixing the cold uniform mixture of the remaining components with the main phase change material in a molten state is to add the cold uniform mixture to the stirred main phase change material in a molten state, and to maintain the main phase change material in a molten state and continue stirring.
8. The method of claim 6 or 7, wherein the phase change energy storage composite is prepared by a method comprising: The temperature control of the heating source for heating the main phase change material is 70℃~80℃.
9. The method of claim 7, wherein the phase change energy storage composite is prepared by a process comprising: The stirring speed is greater than 500 revolutions per minute.
10. The phase change energy storage composite material according to any one of claims 1~5 is applied in solar heat storage or electronic device thermal management.