Composite phase change material, its preparation method, and battery

Abstract

The present invention discloses a composite phase change material, a preparation method thereof, and a battery, belonging to the technical field of heat dissipation. The preparation method includes: dissolving polyoxyethylene with a molecular weight of 2000 Da - 300000 Da in a solvent, and obtaining a polyoxyethylene solution through heating and dissolution; subjecting the polyoxyethylene solution to a freezing treatment at -30°C to -10°C to obtain a polyoxyethylene crystallization solution; placing the polyoxyethylene crystallization solution on the surface of a diaphragm, and obtaining a composite phase change material through a drying and curing treatment. When the composite phase change material is used to prepare a battery, the heat dissipation effect of the battery itself can be effectively improved, thereby improving its cycle service life and safety. Moreover, the preparation method is simple to operate, has strong repeatability, and is convenient for large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation, and particularly to a composite phase change material, a preparation method thereof, and a battery. Background Art

[0002] A phase change thermal insulation material (Phase Change Material, PCM) refers to a substance that changes its form with temperature change and can provide latent heat. The process of a phase change material changing from a solid state to a liquid state or from a liquid state to a solid state is called a phase change process. The phase change thermal insulation material absorbs or releases a large amount of latent heat during the phase change process. When the external environmental temperature rises to the phase change temperature, the phase change material absorbs and stores heat, and itself transforms from a solid state to a liquid state. When the transformation is complete, the heat storage ends; when the external temperature drops to the phase change temperature, the phase change material transforms from a liquid state to a solid state and releases the stored heat.

[0003] Lithium-ion batteries are widely used based on their high power density and excellent electronic characteristics. Taking the use of lithium-ion batteries in electric vehicles as an example, since the number of lithium-ion batteries is usually large, under complex working conditions, the battery pack discharges at different rates and generates heat at different heating rates. If the heat cannot be dissipated in time, combined with the space accumulation effect, it will cause the battery temperature to rise rapidly and even trigger thermal runaway. Excessively high operating temperature and failure to dissipate heat in a timely and effective manner will cause the battery cycle life to decline and may trigger thermal runaway of a single battery or the entire battery pack at any time, resulting in accidents.

[0004] However, currently, the phase change thermal insulation material is usually directly injected between the skeleton of the battery pack and the battery, making it combined with the battery module as a passive thermal management component. However, this method has limited heat dissipation effect and delay for lithium-ion batteries. Summary of the Invention

[0005] In view of this, the present invention provides a composite phase change material, a preparation method thereof, and a battery, which can solve the technical problems existing in the related art.

[0006] Specifically, it includes the following technical solutions:

[0007] On the one hand, a preparation method of a composite phase change material is provided. The preparation method includes:

[0008] Dissolve polyoxyethylene with a molecular weight of 2000Da - 300000Da in a solvent, and obtain a polyoxyethylene solution through heating and dissolution;

[0009] Perform a freezing treatment on the polyoxyethylene solution at -30°C to -10°C to obtain a polyoxyethylene crystallization solution;

[0010] Place the polyoxyethylene crystallization solution on the surface of a diaphragm, and obtain the composite phase change material through drying and solidification treatment.

[0011] In some possible implementation manners, dissolving polyoxyethylene with a molecular weight of 2000 Da - 300000 Da in a solvent, and heating and dissolving to obtain a polyoxyethylene solution, includes:

[0012] Dissolving polyoxyethylene with a molecular weight of 2000 Da - 300000 Da in a solvent, and keeping the temperature at 50°C - 90°C for constant temperature heating for 10 min - 60 min to obtain the polyoxyethylene solution.

[0013] In some possible implementation manners, performing a freezing treatment on the polyoxyethylene solution at -30°C - -10°C to obtain a polyoxyethylene crystal solution, includes:

[0014] Placing the polyoxyethylene solution in a freezing device for freezing treatment for 10 min - 36 h to obtain a polyoxyethylene crystal solution.

[0015] In some possible implementation manners, placing the polyoxyethylene crystal solution on the surface of a diaphragm, and performing a drying and solidifying treatment to obtain the composite phase change material, includes:

[0016] Using a microinjector, placing the polyoxyethylene crystal solution on the surface of the diaphragm.

[0017] In some possible implementation manners, performing the drying and solidifying treatment in air and at room temperature.

[0018] In some possible implementation manners, the material of the diaphragm is selected from PE, PP, PVDF, PA, PSF or PS.

[0019] In some possible implementation manners, the concentration of the polyoxyethylene solution is 0.005 wt% - 0.2 wt%.

[0020] On the other hand, a composite phase change material is provided, and the composite phase change material is prepared by using the preparation method of any one of the above-mentioned composite phase change materials.

[0021] In some possible implementation manners, the thickness of the composite phase change material is 6 μm - 32 μm, and the areal density is 7 g / m 2 ~20 g / m 2 。

[0022] On yet another hand, a battery is provided, and the battery includes any one of the above-mentioned composite phase change materials.

[0023] The beneficial effects of the technical solution provided by the embodiments of the present invention at least include:

[0024] The preparation method of the composite phase change material provided by the embodiment of the present invention enables the polyethylene oxide solution to be cryogenically treated at -30°C to -10°C, so that the polyethylene oxide rapidly cools down and crystallizes, thereby forming a polyethylene oxide phase change material capable of undergoing phase change. Then, the polyethylene oxide crystallization liquid is placed on the surface of the diaphragm, so that the polyethylene oxide phase change material solidifies and forms on the surface of the diaphragm, thereby obtaining a composite phase change material simultaneously containing the diaphragm and the polyethylene oxide phase change material. It can be seen that the preparation method of the composite phase change material provided by the embodiment of the present invention can not only introduce the polyethylene oxide phase change material into the diaphragm, thereby effectively improving the heat dissipation and heat resistance performance of the diaphragm. In this way, when the composite phase change material is used in a battery, the battery can dissipate heat in a timely manner, thereby effectively improving the heat dissipation effect of the battery itself, and further enhancing its cycle service life and safety. Moreover, this preparation method is simple to operate, has strong repeatability, and is convenient for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 It is a DSC curve graph of a series of composite phase change materials provided by the embodiment of the present invention;

[0027] Figure 2 It is a schematic structural diagram of an exemplary composite phase change material provided by the embodiment of the present invention;

[0028] Figure 3 It is a schematic structural diagram of another exemplary composite phase change material provided by the embodiment of the present invention.

[0029] The reference numerals respectively represent:

[0030] 100 - diaphragm;

[0031] 200 - phase change material layer;

[0032] 300 - substrate.

[0033] Through the above drawings, the specific embodiments of the present application have been shown, and there will be more detailed descriptions later. These drawings and text descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0035] To make the technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0036] A phase change thermal insulation material (Phase Change Material, PCM) refers to a substance that changes its form with temperature change and can provide latent heat. The process of the phase change material changing from a solid state to a liquid state or from a liquid state to a solid state is called the phase change process. The phase change thermal insulation material absorbs or releases a large amount of latent heat during the phase change process. When the external environmental temperature rises to the phase change temperature, the phase change material absorbs and stores heat, and itself transforms from a solid state to a liquid state. When the transformation is complete, the heat storage ends; when the external temperature drops to the phase change temperature, the phase change material transforms from a liquid state to a solid state and releases the stored heat.

[0037] Lithium-ion batteries are widely used based on their high power density and superior electronic characteristics. Taking the use of lithium-ion batteries in electric vehicles as an example, since the number of lithium-ion batteries is usually large, under complex working conditions, the battery pack discharges at different rates and generates heat at different heating rates. If the heat cannot be dissipated in time, combined with the space accumulation effect, it will cause the battery temperature to rise rapidly and even trigger thermal runaway. Excessively high operating temperature and failure to dissipate heat in time and effectively will cause the battery cycle life to decline and will trigger thermal runaway of a single battery or the entire battery pack at any time, thus leading to accidents.

[0038] However, currently, the phase change thermal insulation material is usually directly injected between the skeleton of the battery pack and the battery, making it combined with the battery module as a passive thermal management component. However, this method has limited heat dissipation effect and delay for lithium-ion batteries.

[0039] On the one hand, an embodiment of the present invention provides a preparation method of a composite phase change material, and the preparation method includes the following steps:

[0040] Step 1: Dissolve polyoxyethylene with a molecular weight of 2000Da - 300000Da in a solvent, and obtain a polyoxyethylene solution through heating and dissolution.

[0041] Step 2: Freeze the polyoxyethylene solution at -30°C to -10°C to obtain a polyoxyethylene crystal solution.

[0042] Step 3: Place the polyethylene oxide crystallization solution on the surface of the diaphragm, and obtain a composite phase change material through drying and curing treatment.

[0043] In the preparation method of the composite phase change material provided by the embodiment of the present invention, by subjecting the polyethylene oxide solution to a freezing treatment at -30°C to -10°C, the polyethylene oxide is rapidly cooled and crystallized, thereby forming a polyethylene oxide phase change material capable of undergoing a phase change. Then, the polyethylene oxide crystallization solution is placed on the surface of the diaphragm, so that the polyethylene oxide phase change material is cured and formed on the surface of the diaphragm, thereby obtaining a composite phase change material simultaneously containing the diaphragm and the polyethylene oxide phase change material. It can be seen that the preparation method of the composite phase change material provided by the embodiment of the present invention can not only introduce the polyethylene oxide phase change material into the diaphragm, thereby effectively improving the heat dissipation and heat resistance performance of the diaphragm. In this way, when the composite phase change material is used in a battery, the battery can dissipate heat in a timely manner, thereby effectively improving the heat dissipation effect of the battery itself, and further enhancing its cycle service life and safety. Moreover, this preparation method is simple to operate, has strong repeatability, and is convenient for large-scale production.

[0044] The following respectively gives an exemplary elaboration on the specific operations and their effects of each step involved in the above preparation method.

[0045] For step 1, it dissolves polyethylene oxide with a molecular weight of 2000Da - 300000Da in a solvent, and obtains a polyethylene oxide solution through heating and dissolution.

[0046] According to the polymer nomenclature rules, both polyethylene oxide (PEO) and polyethylene glycol (PEG) can be called polyethylene oxide. Among them, polyethylene glycol (PEG) tends to be an oligomer, which is polyethylene oxide with a molecular weight less than or equal to 20000Da, and polyethylene oxide (PEO) tends to be a polymer, which is polyethylene oxide with a molecular weight greater than 20000Da.

[0047] Polyethylene glycol PEG has different configurations in space, which includes the conventional PEG structure and the monofunctional mPEG structure (i.e., monomethoxy ether PEG, with a very low diol content).

[0048] Polyethylene oxides with different molecular weights correspond to different phase change temperatures (i.e., glass transition temperatures), see Figure 1 , which shows the phase change temperatures corresponding to the composite phase change materials obtained from polyethylene oxides with different molecular weights.

[0049] In the embodiment of the present invention, the molecular weight of the polyethylene oxide can be 2000Da - 20000Da, and 20000Da - 300000Da, etc.

[0050] The molecular weights of polyethylene glycol include, but are not limited to: 2000Da, 4000Da, 5000Da, 6000Da, 8000Da, 9000Da, 10000Da, 15000Da, 20000Da, 30000Da, 40000Da, 50000Da, 60000Da, 70000Da, 80000Da, 90000Da, 100000Da, 110000Da, 120000Da, 130000Da, 140000Da, 150000Da, 160000Da, 170000Da, 180000Da, 190000Da, 200000Da, 210000Da, 220000Da, 230000Da, 240000Da, 250000Da, 260000Da, 270000Da, 280000Da, 290000Da, 300000Da, etc.

[0051] In some examples, dissolving polyethylene glycol with a molecular weight of 2000Da - 300000Da in a solvent and heating for dissolution to obtain a polyethylene glycol solution includes: dissolving polyethylene glycol with a molecular weight of 2000Da - 300000Da in a solvent, and heating at a constant temperature of 50°C to 90°C for 10 min - 60 min to obtain a polyethylene glycol solution.

[0052] By setting the heating temperature at 50°C to 90°C and the heating time at 10 min - 60 min, the polyethylene glycol is fully and thoroughly dissolved to form a polyethylene glycol solution with a uniform texture.

[0053] Exemplarily, the heating temperature includes, but is not limited to, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, etc. The heating time includes, but is not limited to, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, etc.

[0054] In some examples, some suitable solvents include, but are not limited to, toluene, xylene, acetone, etc. For example, toluene can be used as the solvent.

[0055] To enable the polyethylene glycol in the polyethylene glycol solution to fully crystallize, the concentration of the polyethylene glycol solution can be 0.005wt% - 0.2wt%. For example, this includes, but is not limited to: 0.01wt%, 0.05wt%, 0.06wt%, 0.07wt%, 0.08wt%, 0.09wt%, 0.1wt%, 0.11wt%, 0.12wt%, 0.13wt%, 0.14wt%, 0.15wt%, 0.16wt%, 0.17wt%, 0.18wt%, 0.19wt%, 0.2wt%, etc.

[0056] For Step 2, the polyethylene oxide solution is subjected to a freezing treatment at -30°C to -10°C to obtain a polyethylene oxide crystallization solution. By rapidly lowering the temperature, crystal nuclei are generated inside the polyethylene oxide and crystallization occurs, thereby realizing the phase change characteristics of the polyethylene oxide.

[0057] Among them, some applicable freezing temperatures include but are not limited to -30°C, -25°C, -24°C, -23°C, -22°C, -21°C, -20°C, -19°C, -18°C, -17°C, -16°C, etc.

[0058] In some examples, in the embodiment of the present invention, the polyethylene oxide solution is subjected to a freezing treatment at -30°C to -10°C to obtain a polyethylene oxide crystallization solution, including: placing the polyethylene oxide solution in a freezing device for a freezing treatment for 10 min to 36 h to obtain a polyethylene oxide crystallization solution.

[0059] Among them, the freezing device includes but is not limited to a refrigerator, a freezer, a refrigerating machine, etc. Using the freezing device for freezing treatment not only facilitates providing a suitable freezing temperature but also provides a sealed freezing environment.

[0060] Exemplarily, the freezing time includes but is not limited to 30 min, 1 h, 5 h, 10 h, 12 h, 15 h, 17 h, 20 h, 24 h, 30 h, 36 h.

[0061] For Step 3, the polyethylene oxide crystallization solution is placed on the surface of the diaphragm and subjected to a drying and curing treatment to obtain a composite phase change material. In this way, by drying and curing the polyethylene oxide crystallization solution, a phase change material layer is directly formed on the surface of the diaphragm.

[0062] Figure 2 An example of a composite phase change material is shown in Figure 2 As shown, the composite phase change material includes a diaphragm 100 and a phase change material layer 200 formed on the diaphragm 100. Figure 2 The shown composite phase change material can be directly applied.

[0063] In some examples, placing the polyethylene oxide crystallization solution on the surface of the diaphragm and subjecting it to a drying and curing treatment to obtain a composite phase change material includes: using a microsyringe to place the polyethylene oxide crystallization solution on the surface of the diaphragm.

[0064] By using a microsyringe to place the polyethylene oxide crystallization solution on the surface of the diaphragm in an injection manner, this can precisely control the range and thickness of the phase change material layer formed on the surface of the diaphragm, and at the same time, it also facilitates the outflow of the polyethylene oxide crystallization solution.

[0065] In some examples, the drying and curing treatment is carried out in air at room temperature, where the temperature range indicated by the room temperature can be 20°C to 30°C.

[0066] By drying and curing in air at room temperature, it is possible to ensure that the polyethylene oxide crystallization liquid is fully and thoroughly cured, presenting a uniform texture.

[0067] In some examples, when preparing the composite phase change material, the separator can be placed on the substrate, and the substrate is used to support the separator.

[0068] The substrate includes but is not limited to a glass substrate, a ceramic substrate, a metal substrate, a plastic substrate, etc.

[0069] Figure 3 Another composite phase change material is exemplified. Refer to Figure 3 As shown, the composite phase change material includes a separator 100, a phase change material layer 200 formed on the separator 100, and a substrate 300 for supporting the separator 100. Figure 3 The shown composite phase change material can be stored for standby. When in use, the substrate 300 can be removed.

[0070] In the embodiments of the present invention, the separator used can be a battery separator, that is, conventional battery separators can be used in the present invention and used as an energy storage separator.

[0071] In some examples, the material of the separator is selected from PE (polyethylene), PP (polypropylene), PVDF (polyvinylidene fluoride), PA (polyamide), PSF (polysulfone), or PS (polystyrene).

[0072] On the other hand, the embodiments of the present invention also provide a composite phase change material, which is prepared by using any one of the preparation methods of the above-mentioned composite phase change materials.

[0073] Figure 2 A composite phase change material is exemplified. Refer to Figure 2 As shown, the composite phase change material includes a separator 100 and a phase change material layer 200 formed on the separator 100. Figure 2 The shown composite phase change material can be directly applied.

[0074] Figure 3 Another composite phase change material is exemplified. Refer to Figure 3 As shown, the composite phase change material includes a separator 100, a phase change material layer 200 formed on the separator 100, and a substrate 300 for supporting the separator 100. Figure 3 The shown composite phase change material can be stored for standby. When in use, the substrate 300 can be removed.

[0075] The composite phase change material provided by the embodiments of the present invention can be regarded as a composite diaphragm material with a phase change function, wherein the diaphragm 100 is the base film.

[0076] In some examples, the thickness of the composite phase change material is 6 μm to 32 μm, and the areal density is 7 g / m 2 ~20 g / m 2 .

[0077] For example, the thickness of the composite phase change material includes, but is not limited to, 6 μm, 10 μm, 12 μm, 15 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, etc.

[0078] Among them, the thickness of the diaphragm can be 3 μm to 25 μm, which includes, but is not limited to, 3 μm, 4 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, etc.

[0079] The areal density of the composite phase change material includes, but is not limited to, 7 g / m 2 , 8 g / m 2 , 9 g / m 2 , 10 g / m 2 , 11 g / m 2 , 12 g / m 2 , 13 g / m 2 , 14 g / m 2 , 15 g / m 2 , 16 g / m 2 , 17 g / m 2 , 18 g / m 2 , 19 g / m 2 , 20 g / m 2 , etc.

[0080] On the other hand, the embodiments of the present invention also provide a battery, which includes any one of the above-mentioned composite phase change materials.

[0081] Exemplarily, the battery is a lithium-ion battery, which includes a positive electrode, a negative electrode, a separator, and an electrolyte. Among them, the separator is any one of the composite phase change materials described in the embodiments of the present invention.

[0082] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. For those without specific technical or conditions noted in the examples, the techniques or conditions described in the literature in this field or according to the product specifications are followed. For reagents or instruments without the manufacturer noted, they are all conventional products that can be obtained through commercial purchases.

[0083] Example 1

[0084] This Example 1 provides a composite phase change material. As shown in the appendix Figure 3 The composite phase change material includes a diaphragm 100, a phase change material layer 200 formed on the diaphragm 100, and a substrate 300 for supporting the diaphragm 100. Among them, the material of the diaphragm 100 is PE, the phase change material layer 200 is prepared from polyoxyethylene with a molecular weight of 100,000 Da, and the substrate 300 is a glass plate.

[0085] The preparation method of the composite phase change material provided in Example 1 is as follows:

[0086] Step a: Dissolve polyoxyethylene with a molecular weight of 100,000 Da (abbreviated as PEO 100000) in toluene, and heat it at a constant temperature of 65 °C for 30 min to obtain a polyoxyethylene solution with a mass concentration of 0.2 wt%.

[0087] Step b: Place the polyoxyethylene solution in a refrigerator and freeze it at a temperature of -20 °C for 24 h to obtain a polyoxyethylene crystal solution.

[0088] Step c: Place the diaphragm on the substrate, use a microinjector to place the polyoxyethylene crystal solution on the surface of the diaphragm, and perform a drying and curing treatment in the air at 25 °C to obtain the composite phase change material of Example 1.

[0089] After testing, the phase change temperature of the composite phase change material provided in Example 1 is 70.92 °C (see Figure 1 ), its thickness is 25 μm, and its areal density is 10 g / m 2 .

[0090] Example 2

[0091] This Example 2 provides a composite phase change material. As shown in the appendix Figure 3 The composite phase change material includes a diaphragm 100, a phase change material layer 200 formed on the diaphragm 100, and a substrate 300 for supporting the diaphragm 100. Among them, the material of the diaphragm 100 is PE, the phase change material layer 200 is prepared from polyoxyethylene with a molecular weight of 100,000 Da, and the substrate 300 is a glass plate.

[0092] The preparation method of the composite phase change material provided in Example 2 is as follows:

[0093] Step a: Dissolve polyethylene oxide (abbreviated as PEG 8000) with a molecular weight of 8000 Da in toluene, and keep heating at a constant temperature of 68 °C for 20 min to obtain a polyethylene oxide solution with a mass concentration of 0.2 wt%.

[0094] Step b: Place the polyethylene oxide solution in a refrigerator and freeze it at a temperature of -25 °C for 12 h to obtain a polyethylene oxide crystallization solution.

[0095] Step c: Place the diaphragm on the substrate, and use a microinjector to place the polyethylene oxide crystallization solution on the surface of the diaphragm, and perform drying and curing treatment in the air at 25 °C to obtain the composite phase change material of Example 2.

[0096] After testing, the phase change temperature of the composite phase change material provided in Example 2 is 60.85 °C (see Figure 1 ), its thickness is 20 μm, and its areal density is 15 g / m 2 .

[0097] Example 3

[0098] This Example 3 provides a composite phase change material, as shown in the attached Figure 3 . The composite phase change material includes a diaphragm 100, a phase change material layer 200 formed on the diaphragm 100, and a substrate 300 for supporting the diaphragm 100. Among them, the material of the diaphragm 100 is PE, the phase change material layer 200 is prepared from polyethylene oxide with a molecular weight of 100000 Da, and the substrate 300 is a glass plate.

[0099] The preparation method of the composite phase change material provided in Example 3 is as follows:

[0100] Step a: Dissolve polyethylene oxide (abbreviated as PEG 4000) with a molecular weight of 4000 Da in toluene, and keep heating at a constant temperature of 60 °C for 40 min to obtain a polyethylene oxide solution with a mass concentration of 0.2 wt%.

[0101] Step b: Place the polyethylene oxide solution in a refrigerator and freeze it at a temperature of -10 °C for 36 h to obtain a polyethylene oxide crystallization solution.

[0102] Step c: Place the diaphragm on the substrate, and use a microinjector to place the polyethylene oxide crystallization solution on the surface of the diaphragm, and perform drying and curing treatment in the air at 20 °C to obtain the composite phase change material of Example 3.

[0103] After testing, the phase change temperature of the composite phase change material provided in Example 3 is 62.67 °C (seeFigure 1 ), with a thickness of 30 μm and a areal density of 20 g / m 2 .

[0104] Example 4

[0105] The composite phase change material of Example 4 was prepared according to the same preparation method and operating parameters as in Example 1, except that in the composite phase change material provided in Example 4, the phase change material layer was prepared from polyethylene oxide with a molecular weight of 20,000 Da (abbreviated as mPEG-SH 20000), see Figure 1 , and the phase change temperature of the composite phase change material provided in Example 4 was 64.74 °C.

[0106] Example 5

[0107] The composite phase change material of Example 5 was prepared according to the same preparation method and operating parameters as in Example 1, except that in the composite phase change material provided in Example 5, the phase change material layer was prepared from polyethylene oxide with a molecular weight of 300,000 Da (abbreviated as PEO 300000), see Figure 1 , and the phase change temperature of the composite phase change material provided in Example 5 was 69.37 °C.

[0108] Example 6

[0109] The composite phase change material of Example 6 was prepared according to the same preparation method and operating parameters as in Example 1, except that in the composite phase change material provided in Example 6, the phase change material layer was prepared from polyethylene oxide with a molecular weight of 20,000 Da (abbreviated as PEG 20000), see Figure 1 , and the phase change temperature of the composite phase change material provided in Example 6 was 66.40 °C.

[0110] Example 7

[0111] The composite phase change material of Example 7 was prepared according to the same preparation method and operating parameters as in Example 1, except that in the composite phase change material provided in Example 7, the phase change material layer was prepared from polyethylene oxide with a molecular weight of 2,000 Da (abbreviated as PEG 2000), see Figure 1 , and the phase change temperature of the composite phase change material provided in Example 7 was 55.41 °C.

[0112] Example 8

[0113] The composite phase change material of Example 8 was prepared according to the same preparation method and operating parameters as in Example 1, except that in the composite phase change material provided in Example 8, the phase change material layer was prepared from monofunctional polyethylene oxide with a molecular weight of 2,000 Da (abbreviated as mPEG 2000), see Figure 1, the phase change temperature of the composite phase change material provided in Example 8 is 54.96 °C.

[0114] The above description is only for the convenience of those skilled in the art to understand the technical solution of the present invention, and is not intended to limit the present invention. 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 preparation method of a composite phase change material, characterized in that The preparation method includes: Dissolve polyoxyethylene with a molecular weight of 2000Da - 300000Da in a solvent, and heat and dissolve it to obtain a polyoxyethylene solution; Place the polyoxyethylene solution in a freezing device, and perform freezing treatment at -30°C to -10°C for 10 min to 36 h to obtain a polyoxyethylene crystallization solution. The freezing device is a refrigerator, a freezer or a chiller; Use a microinjector to place the polyoxyethylene crystallization solution on the surface of the diaphragm, and perform drying and curing treatment to obtain the composite phase change material.

2. The preparation method of the composite phase change material according to claim 1, characterized in that, The step of dissolving polyoxyethylene with a molecular weight of 2000Da - 300000Da in a solvent, and heating and dissolving it to obtain a polyoxyethylene solution includes: Dissolve polyoxyethylene with a molecular weight of 2000Da - 300000Da in a solvent, and keep heating at a temperature of 50°C to 90°C for 10 min - 60 min to obtain the polyoxyethylene solution.

3. The preparation method of the composite phase change material according to claim 1, characterized in that Perform the drying and curing treatment in air at room temperature.

4. The preparation method of the composite phase change material according to any one of claims 1-3, characterized in that, The material of the diaphragm is selected from PE, PP, PVDF, PA, PSF or PS.

5. The preparation method of the composite phase change material according to any one of claims 1-3, characterized in that, The concentration of the polyoxyethylene solution is 0.005wt% - 0.2wt%.

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