All-weather power battery thermal management system based on double-layer flexible phase change material

Abstract

The invention discloses an all-weather power battery thermal management system based on a double-layer flexible phase-change material. The system comprises the double-layer flexible phase-change material which is constructed on the outer side of a power battery, is composed of an inner-layer flexible phase-change material and an outer-layer flexible phase-change material and has a sleeve structure; the double-layer flexible phase change material is tightly attached to the outer side surface of the power battery; when the power battery needs to be cooled at a high temperature, the double-layer flexible phase change material can absorb heat of the power battery and store the heat in a latent heat form; when the power battery needs to be heated at a low temperature, heat is transferred to the power battery in a mode of heating the flexible phase-change material on the outer layer. According to the power battery thermal management system, the problem that the contact thermal resistance is large when the rigid phase change material makes contact with the battery is solved, the phase change material generates phase change high-density latent heat storage and heat transfer when the power battery is cooled at high temperature, heat can be efficiently generated and transferred when the power battery is heated at low temperature, and efficient energy-saving thermal control under the all-weather condition can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of power battery thermal management, and in particular to an all-weather power battery thermal management system based on a double-layer flexible phase change material. Background Art

[0002] Power batteries are widely used as electrochemical energy storage devices in electric vehicles, distributed energy storage and electronic devices. Temperature has a great impact on performance. Phase change materials have good thermal management effects, while traditional rigid phase change materials have a fixed shape during use, making them difficult to match when dealing with some different types of batteries. Rigid contact surfaces are prone to produce large contact thermal resistance when in contact with the battery surface, reducing heat transfer efficiency.

[0003] At present, there are a lot of studies on the use of phase change materials for power battery cooling, but the poor electrothermal conversion performance of pure phase change materials leads to poor heating performance, which cannot meet the heating needs of power batteries. When the phase change material is modified by adding highly conductive fillers to give it electrothermal conversion performance, a circuit path is formed between the phase change material and the power battery, which is prone to short circuit. Therefore, when the current phase change material is used for power battery thermal management, it can only be used for cooling and cannot achieve full-climate thermal management. Summary of the invention

[0004] In view of the above shortcomings of the prior art, the present invention provides an all-weather power battery thermal management system based on a double-layer flexible phase change material to solve the technical problems that the existing phase change material has a fixed shape, and the rigid contact surface is easy to generate a large contact thermal resistance when in contact with the surface of the power battery, and the conventional modified phase change material is easy to form a path with the power battery while improving the conductivity. Specifically, the inventor prepared a high thermal conductivity, high electrical conductivity flexible phase change material and an insulating flexible phase change material by a reverse phase conversion method and a melt blending method, and innovatively designed a double-layer flexible phase change material power battery thermal management structure, that is, the inner layer of the flexible phase change material has electrical insulation to prevent the formation of a path with the battery, and the outer layer of the flexible phase change material has high electrical conductivity and high thermal conductivity to perform electric heat conversion for heating the battery. On this basis, the shape memory characteristics and flexibility of the flexible phase change material are utilized, and the battery is tightly installed in the double-layer structure through the heat shrinkage principle and the interference fit principle, thereby reducing the contact thermal resistance and realizing efficient all-weather thermal management.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A full-weather power battery thermal management system based on a double-layer flexible phase change material, the power battery thermal management system comprising a double-layer flexible phase change material having a sleeve structure composed of an inner layer flexible phase change material and an outer layer flexible phase change material constructed on the outside of the power battery; the inner layer flexible phase change material is arranged in close contact with the outer surface of the power battery, and the outer layer flexible phase change material is arranged in close contact with the inner layer flexible phase change material; wherein, when the power battery is in a high-temperature environment and needs to be cooled, the inner layer flexible phase change material and the outer layer flexible phase change material can absorb the heat of the power battery and store it in the form of latent heat; when the power battery is in a low-temperature environment and needs to be heated, the heat can be transferred to the power battery in sequence through the outer layer flexible phase change material and the inner layer flexible phase change material by heating the outer layer flexible phase change material.

[0007] As a preferred technical solution, the power battery is installed with the inner layer flexible phase change material and the outer layer flexible phase change material to achieve close fit through the heat shrinkage principle and the interference fit principle.

[0008] As a preferred technical solution, the double-layer flexible phase change material is constructed by double molten extrusion. The double-layer flexible phase change material with a sleeve structure prepared by the present invention has no gap in the middle because the double-layer sleeve structure is double extruded during preparation. After perfectly matching with the power battery, the contact thermal resistance between the power battery and the double-layer sleeve structure can be greatly reduced.

[0009] As a preferred technical solution, the inner layer flexible phase change material is an insulating flexible phase change material, and the outer layer flexible phase change material is a high thermal conductivity and high electrical conductivity flexible phase change material.

[0010] As a preferred technical solution, the outer layer flexible phase change material is first melted in cyclohexane by a reverse phase conversion method, and then the first phase change material and the carbon-based material are mixed and heated to mix evenly. The high thermal conductivity and high electrical conductivity outer layer flexible phase change material prepared by the present invention can have a certain flexibility after adding the carbon-based material, and can also improve the thermal conductivity and electrical conductivity, so that it can perform effective electric heat conversion, and the latent heat storage value is within the theoretical range.

[0011] As a preferred technical solution, the carbon-based material is at least one of expanded graphite, carbon nanotubes and graphene. The carbon-based material is mainly used to provide thermal conductivity and electrical conductivity. Different thermal conductivity and electrical conductivity are obtained according to different contents.

[0012] As a preferred technical solution, the inner layer flexible phase change material is prepared by melting and blending the second phase change material and the thermoplastic polyether ester elastomer in a high temperature oil bath environment. The inner layer flexible phase change material prepared by the present invention has strong flexibility and high electrical insulation after adding the thermoplastic polyether ester elastomer, and the thermal conductivity is improved by adding an appropriate amount of expanded graphite, thereby ensuring electrical insulation and high thermal conductivity.

[0013] The material that provides flexibility for the outer layer flexible phase change material and the inner layer flexible phase change material of the present application is mainly thermoplastic polyether ester elastomer. The molecular structure of the thermoplastic polyether ester elastomer is a block copolymer composed of a hard segment and a soft segment. The hard segment mainly provides the material with mechanical strength and heat resistance, while the soft segment mainly provides the material with flexibility and elasticity, which means that the toughness of plastic and the softness of rubber can be taken into account at the same time. The greater the content, the better the flexibility, and it can provide insulation properties. The thermoplastic polyether ester elastomer is a multi-block polymer formed by the hard segments composed of polybutylene terephthalate and the soft segments composed of polyalkylene ether glycol terephthalate, which are bonded to each other.

[0014] As a preferred technical solution, the first phase change material and the second phase change material are independently selected from at least one phase change material having a phase change temperature of 35 to 55°C.

[0015] As a preferred technical solution, the first phase change material and the second phase change material are independently selected from at least one of paraffin, inorganic salt, and organic acid. The phase change material is preferably paraffin with a melting point of 42°C, which is mainly used to provide latent heat value and can absorb the heat released by the power battery while keeping the temperature unchanged.

[0016] The present invention is an all-weather power battery thermal management system based on a double-layer flexible phase change material. The battery is wrapped by two layers of flexible phase change materials, the inner layer is a high thermal conductivity, high insulation flexible phase change material, and the outer layer is a high thermal conductivity, high electrical conductivity flexible phase change material. When cooling is required in a high-temperature environment, the flexible phase change material undergoes a phase change to absorb the heat of the battery and store it in the form of latent heat; when heating is required in a low-temperature environment, the outer layer of the flexible phase change material is powered on for heating, and the high electrical conductivity and high thermal conductivity of the outer layer of the flexible phase change material are used to quickly generate heat and transfer it to the inner layer of the phase change material (the phase change material has not changed phase at this time), and the inner layer of the phase change material transfers the heat to the battery and remains insulated from the battery. Whether the battery is cooled at high temperature or heated at low temperature, the flexibility of the phase change material can greatly reduce the thermal resistance of the contact surface (the contact surface between the inner layer of the phase change material and the battery, and the contact surface between the inner and outer layers of the phase change material), thereby improving the heat transfer efficiency. The power battery thermal management system of the double-layer flexible phase change material of the present invention not only solves the problem of large contact thermal resistance when the rigid phase change material is in contact with the battery, but also the phase change material undergoes phase change to store and transfer high-density latent heat when the battery is cooled at high temperature, and can efficiently generate and transfer heat when heated at low temperature, thereby realizing all-weather thermal management.

[0017] Another aspect of the present invention is to provide a method for constructing an all-weather power battery thermal management system based on the above-mentioned dual-channel shaped phase change material, which comprises the following steps:

[0018] S1: According to the different functionalities of the prepared materials, weigh 60-70% paraffin wax, 20-40% thermoplastic polyether ester elastomer, 5-10% expanded graphite, 1.75-3.75% graphene and 0.75-1.35% carbon nanotubes in a mass ratio for preparing a high thermal conductivity and high electrical conductivity flexible phase change material; weigh 55-60% paraffin wax, 30-40% thermoplastic polyether ester elastomer and 3-5% expanded graphite for preparing an insulating flexible phase change material.

[0019] S2: First, the paraffin wax / expanded graphite / carbon nanotubes / graphene prepared in step S1 are uniformly mixed at a temperature above the melting point of paraffin wax, and then the thermoplastic polyether ester elastomer prepared in step S1 is melted in cyclohexane at an ambient temperature of 70 to 90° C., and then the mixed paraffin wax / expanded graphite / carbon nanotubes / graphene are added thereto, stirred for a certain period of time, and vacuum dried to obtain a high thermal conductivity, high electrical conductivity flexible phase change material.

[0020] S3: Put the paraffin wax and expanded graphite prepared in step S1 into a beaker and heat them in a high-temperature oil bath until the paraffin wax is completely melted, then add the thermoplastic polyether ester elastomer and stir for a certain period of time to obtain an insulating flexible phase change material.

[0021] S4: Based on the high thermal conductivity, high electrical conductivity flexible phase change material and insulating flexible phase change material prepared in steps S2 and S3, the high thermal conductivity, high electrical conductivity flexible phase change material is arranged in the outer layer, and the insulating flexible phase change material is arranged in the inner layer, forming a double-layer sleeve structure with an inner layer having insulation and an outer layer having high electrical conductivity. The molten high thermal conductivity, high electrical conductivity flexible phase change material is poured into a steel sleeve, and a rod with a larger diameter is used to extrude the molten high thermal conductivity, high electrical conductivity flexible phase change material to form an outer sleeve with a larger diameter (i.e., an outer flexible phase change material), and then the molten insulating flexible phase change material is poured into the prepared outer sleeve, and a rod with a smaller diameter is used to perform a secondary extrusion on the insulating flexible phase change material in the outer sleeve to form an inner sleeve with a certain inner core diameter (i.e., an inner flexible phase change material), thereby forming a double-layer flexible phase change material with a sleeve structure.

[0022] S5: Based on the double-layer flexible phase change material with a sleeve structure prepared in step S4, the battery can be installed through the principle of heat shrinkage and interference fit by utilizing its shape memory characteristics and flexibility. The double-layer sleeve structure with a certain inner diameter is heated to above the phase change point of paraffin, and the aperture is enlarged using a rod. After cooling, a double-layer sleeve structure with an enlarged inner diameter is obtained, and the battery is inserted into the double-layer sleeve structure using interference fit. The sleeve is subsequently heated again to above the melting point of paraffin to shrink the inner diameter to its original size, thereby completing the installation of the battery.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention is based on a double-layer flexible phase change material for all-weather power battery thermal management system. It innovatively adopts a double-layer flexible phase change material structure design, and achieves close fit between the power battery and the inner and outer flexible phase change materials through a unique heat shrink and interference fit method, thereby effectively reducing the contact thermal resistance and improving the heat transfer efficiency. This design not only solves the problem of large contact thermal resistance when the rigid phase change material contacts the battery, but also achieves efficient cooling in high temperature environments and rapid heating in low temperature environments through the synergistic effect of the inner layer of insulating flexible phase change material and the outer layer of high thermal conductivity and high electrical conductivity flexible phase change material, thereby achieving efficient and energy-saving thermal control under all-weather conditions and improving the performance and life of the power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flexible display of the sample morphology of the high thermal conductivity and high electrical conductivity flexible phase change material of Example 1 of the present invention.

[0026] Figure 2 This is a flexible display of the sample morphology of the insulating flexible phase change material of Example 1 of the present invention.

[0027] Figure 3 The scanning electron microscope (SEM) photographs of the high thermal conductivity, high electrical conductivity flexible phase change material and the insulating flexible phase change material of Example 1 of the present invention are shown.

[0028] Figure 4 This is a schematic diagram of the preparation of a double-layer flexible phase change material in Example 1 of the present invention, in which a high thermal conductivity and high electrical conductivity flexible phase change material is arranged in an outer layer, and an insulating flexible phase change material is arranged in an inner layer, forming a sleeve structure with an inner layer having insulation and an outer layer having high electrical conductivity.

[0029] Figure 5 This is a schematic diagram of installing a power battery by utilizing the shape memory characteristics and flexibility of an insulating flexible phase change material through the principle of heat shrinkage combined with the principle of interference fit according to Example 1 of the present invention.

[0030] Figure 6Schematic diagram of thermal conductivity comparison of high thermal conductivity, high electrical conductivity flexible phase change material and insulating flexible phase change material in Example 1 of the present invention.

[0031] Figure 7 This is a schematic diagram of the results of testing the contact thermal resistance between the double-layer flexible phase change material and the battery after the battery is installed in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0033] Example 1

[0034] This embodiment is an all-weather power battery thermal management system based on a double-layer flexible phase change material. The power battery thermal management system includes a double-layer flexible phase change material with a sleeve structure composed of an inner layer flexible phase change material and an outer layer flexible phase change material, which is constructed on the outside of the power battery; the inner layer flexible phase change material is arranged close to the outer surface of the power battery, and the outer layer flexible phase change material is arranged close to the inner layer flexible phase change material; wherein, when the power battery is in a high temperature environment and needs to be cooled, the inner layer flexible phase change material and the outer layer flexible phase change material can absorb the heat of the power battery and store it in the form of latent heat; when the power battery is in a low temperature environment and needs to be heated, the heat can be transferred to the power battery in sequence through the outer layer flexible phase change material and the inner layer flexible phase change material by heating the outer layer flexible phase change material. The inner layer flexible phase change material is an insulating flexible phase change material, and the outer layer flexible phase change material is a high thermal conductivity and high electrical conductivity flexible phase change material.

[0035] The method for constructing an all-weather power battery thermal management system based on a double-layer flexible phase change material in this embodiment includes the following steps:

[0036] S1: According to the required performance, 63% paraffin wax, 26.5% thermoplastic polyether ester elastomer, 8% expanded graphite, 1.75% graphene and 0.75% carbon nanotubes are weighed by weight to prepare a high thermal conductivity and high electrical conductivity flexible phase change material; 56.9% paraffin wax, 38.1% thermoplastic polyether ester elastomer and 5% expanded graphite are weighed to prepare an insulating flexible phase change material, wherein the thermoplastic polyether ester elastomer is a multi-block polymer formed by mutual bonding of hard segments composed of polybutylene terephthalate and soft segments composed of polyalkylene ether glycol terephthalate.

[0037] S2: First, the paraffin wax / expanded graphite / graphene / carbon nanotubes prepared in S1 are melted at 60°C and mixed evenly, then the thermoplastic polyether ester elastomer prepared in S1 is melted in a cyclohexane solution at 80°C, and then the mixed paraffin wax / expanded graphite / carbon nanotubes / graphene are added thereto, stirred for 40 minutes, and dried in a vacuum drying oven at 70°C for 6 hours to obtain a high thermal conductivity and high electrical conductivity flexible phase change material, such as Figure 1 shown.

[0038] S3: Melt the paraffin wax / expanded graphite prepared in S1 at 60°C, then add the thermoplastic polyether ester elastomer and the mixed paraffin wax / expanded graphite into an oil bath at 180°C and stir for 40 minutes to obtain an insulating flexible phase change material, such as Figure 2 shown.

[0039] S4: Based on the flexible phase change material prepared by S2 and S3, the molten high thermal conductivity and high electrical conductivity flexible phase change material is first poured into a steel sleeve, and the molten high thermal conductivity and high electrical conductivity flexible phase change material is extruded using a rod with a diameter of 24 mm to form an outer sleeve with a diameter of 24 mm (i.e., the outer flexible phase change material), and then the molten insulating flexible phase change material is poured into the prepared outer sleeve, and the insulating flexible phase change material in the outer sleeve is extruded for a second time using a rod with a diameter of 17 mm to form an inner sleeve with an inner core diameter of 17 mm (i.e., the inner flexible phase change material), thereby forming a double-layer flexible phase change material with a sleeve structure, such as Figure 4 shown.

[0040] S5: Based on the double-layer flexible phase change material with a sleeve structure prepared by S4, the shape memory property and flexibility can be used to install the battery through heat shrinkage. The double-layer sleeve structure with an inner diameter of 17 mm is heated to above the phase change point of paraffin, and a rod with a diameter of 17.5 mm is used to expand the aperture to 17.5 mm. After cooling to 25°C, a double-layer sleeve structure with an inner diameter of 17.5 mm is obtained. Then, an 18650 battery with an outer diameter of 18 mm is inserted into the double-layer sleeve structure by interference fit. The sleeve is then heated again to above the melting point of paraffin to shrink the inner diameter to 17.5 mm, completing the installation of the battery. Figure 5 shown.

[0041] The test results show that if Figure 3 As shown in the figure, they are the SEM images of the outer layer high thermal conductivity, high electrical conductivity flexible phase change material and the inner layer insulating flexible phase change material. The structure of the internal components is completely invisible and is filled with a mixture of paraffin wax / thermoplastic polyether ester elastomer. From the SME image, it can be seen that the surface is flat, indicating that the mixture is relatively sufficient, while the high thermal conductivity, high electrical conductivity flexible phase change material has tiny protrusions on the surface due to the large amount of fillers. Figure 6As shown in the figure, the thermal conductivity of the high thermal conductivity and high electrical conductivity flexible phase change material increases from 0.17W / (m·K) to 4.23W / (m·K) after adding carbon-based materials, and the thermal conductivity of the insulating flexible phase change material is as high as 1.2W / (m·K). After the battery is installed, its contact thermal resistance is tested as follows Figure 7 As shown in the figure, the contact thermal resistance decreases with increasing temperature, and the final contact thermal resistance is only 0.15℃ / W.

[0042] Comparative Example 1

[0043] The construction method of the all-weather power battery thermal management system based on the double-layer flexible phase change material in this comparative example is basically the same as that in Example 1, except that, in the construction method of this comparative example, in step S1, 67% of paraffin wax, 24.5% of thermoplastic polyether ester elastomer, 6% of expanded graphite, 1.75% of graphene and 0.75% of carbon nanotubes are weighed by weight to prepare high thermal conductivity and high electrical conductivity flexible phase change material; 59.3% of paraffin wax, 39.7% of thermoplastic polyether ester elastomer and 1% of expanded graphite are weighed to prepare insulating flexible phase change material.

[0044] The test results show that the thermal conductivity of the outer layer flexible phase change material of this comparative example is 2.12 W / (m·K), and the thermal conductivity of the inner layer flexible phase change material is 0.28 W / (m·K).

[0045] Example 2

[0046] The construction method of the all-weather power battery thermal management system based on the double-layer flexible phase change material in this embodiment is basically the same as that in Example 1, except that, in the construction method of this embodiment, in step S1, 66% of paraffin wax, 24.5% of thermoplastic polyether ester elastomer, 6% of expanded graphite, 2.45% of graphene and 1.05% of carbon nanotubes are weighed by weight to prepare high thermal conductivity and high electrical conductivity flexible phase change material; 58.1% of paraffin wax, 38.9% of thermoplastic polyether ester elastomer and 3% of expanded graphite are weighed to prepare insulating flexible phase change material.

[0047] The test results show that the thermal conductivity of the outer layer of the flexible phase change material of this embodiment is 2.15 W / (m·K), and the thermal conductivity of the inner layer of the flexible phase change material is 0.48 W / (m·K).

[0048] Example 3

[0049] The construction method of the all-weather power battery thermal management system based on the double-layer flexible phase change material in this embodiment is basically the same as that in Example 1, except that, in the construction method of this embodiment, in step S1, 65% of paraffin wax, 24.5% of thermoplastic polyether ester elastomer, 6% of expanded graphite, 3.15% of graphene and 1.35% of carbon nanotubes are weighed by weight to prepare high thermal conductivity and high electrical conductivity flexible phase change material; 56.9% of paraffin wax, 38.1% of thermoplastic polyether ester elastomer and 5% of expanded graphite are weighed to prepare insulating flexible phase change material.

[0050] The test results show that the thermal conductivity of the outer layer of the flexible phase change material of this embodiment is 2.30 W / (m·K), and the thermal conductivity of the inner layer of the flexible phase change material is 1.20 W / (m·K).

[0051] Example 4

[0052] The construction method of the all-weather power battery thermal management system based on the double-layer flexible phase change material in this embodiment is basically the same as that in Example 1, except that, in the construction method of this embodiment, in step S1, 61% of paraffin wax, 26.5% of thermoplastic polyether ester elastomer, 10% of expanded graphite, 1.75% of graphene and 0.75% of carbon nanotubes are weighed by weight to prepare high thermal conductivity and high electrical conductivity flexible phase change material; 56.9% of paraffin wax, 38.1% of thermoplastic polyether ester elastomer and 5% of expanded graphite are weighed to prepare insulating flexible phase change material.

[0053] The test results show that the thermal conductivity of the outer layer flexible phase change material of this embodiment is 4.42 W / (m·K), and the thermal conductivity of the inner layer flexible phase change material is 1.20 W / (m·K).

[0054] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention, and these changes and improvements fall within the scope of the present invention claimed.

Claims

1. An all-weather power battery thermal management system based on double-layer flexible phase change material, characterized in that: The power battery thermal management system includes a double-layer flexible phase change material with a sleeve structure composed of an inner layer flexible phase change material and an outer layer flexible phase change material, which is constructed on the outside of the power battery; the inner layer flexible phase change material is arranged close to the outer surface of the power battery, and the outer layer flexible phase change material is arranged close to the inner layer flexible phase change material; wherein, when the power battery is in a high temperature environment and needs to be cooled, the inner layer flexible phase change material and the outer layer flexible phase change material can absorb the heat of the power battery and store it in the form of latent heat; when the power battery is in a low temperature environment and needs to be heated, the heat can be transferred to the power battery in sequence through the outer layer flexible phase change material and the inner layer flexible phase change material by heating the outer layer flexible phase change material.

2. The all-weather power battery thermal management system based on double-layer flexible phase change material as claimed in claim 1, characterized in that: The power battery is installed with the inner layer flexible phase change material and the outer layer flexible phase change material to achieve close fit through the heat shrinkage principle and the interference fit principle.

3. The all-weather power battery thermal management system based on double-layer flexible phase change material as claimed in claim 1, characterized in that: The double-layer flexible phase change material is constructed by double molten state extrusion.

4. The all-weather power battery thermal management system based on double-layer flexible phase change material as claimed in claim 1, characterized in that: The inner layer flexible phase change material is an insulating flexible phase change material, and the outer layer flexible phase change material is a high thermal conductivity and high electrical conductivity flexible phase change material.

5. The all-weather power battery thermal management system based on double-layer flexible phase change material as claimed in claim 1, characterized in that: The outer layer flexible phase change material is firstly prepared by melting a thermoplastic polyether ester elastomer in cyclohexane by a reverse phase conversion method, and then mixing the first phase change material and the carbon-based material, heating and mixing them uniformly.

6. The all-weather power battery thermal management system based on double-layer flexible phase change material as claimed in claim 5, characterized in that: The carbon-based material is at least one of expanded graphite, carbon nanotubes and graphene.

7. The all-weather power battery thermal management system based on double-layer flexible phase change material as claimed in claim 1, characterized in that: The inner layer flexible phase change material is prepared by heating and mixing the second phase change material and the thermoplastic polyether ester elastomer in a high-temperature oil bath environment through a melt blending method.

8. The all-weather power battery thermal management system based on double-layer flexible phase change material as claimed in claim 5 or 7, characterized in that: The first phase change material and the second phase change material are independently selected from at least one phase change material having a phase change temperature of 35 to 55°C.

9. The all-weather power battery thermal management system based on double-layer flexible phase change material as claimed in claim 5 or 7, characterized in that: The first phase change material and the second phase change material are independently selected from at least one of paraffin, inorganic salt and organic acid.

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