Temperature control film and temperature control system and battery using same

Abstract

The invention provides a temperature control film as well as a temperature control system and a battery applying the temperature control film. The temperature control film comprises a first functional layer and a second functional layer which are attached to each other, wherein the first functional layer comprises graphene, and the second functional layer comprises fluorinated graphene and a viscous substance; the fluorine-carbon ratio of the fluorinated graphene is (0.9-1.2): 1; the viscous substance comprises at least one of acrylate, polyurethane and epoxy resin. According to the invention, firstly, the first functional layer of graphene is used as a heat conduction module, so that heating and heat conduction performance can be effectively realized; and secondly, the second functional layer has high heat-conducting property and high insulating property. Moreover, the mechanical strength and the heat-resistant effect of the second functional layer and the bonding effect between the second functional layer and the first functional layer can be enhanced by utilizing the synergistic effect between the viscous substance and the fluorinated graphene in the second functional layer. Therefore, when the temperature control film provided by the invention is used for the lithium battery, efficient heating and heat conduction can be provided at low temperature, and effective heat dissipation can be realized at high temperature, so that a good temperature control effect is realized, and the use safety of the battery is improved. And on the other hand, the temperature control film provided by the invention is simple in structure, convenient to prepare and convenient for large-scale production and use.

Description

Technical Field

[0001] The present invention belongs to the field of thermal conductive films, and in particular relates to a temperature control film and a temperature control system and a battery using the same. Background Art

[0002] As a key material in the new energy industry, lithium-ion batteries are affected by a variety of factors during use. Temperature is a key factor, with the optimal operating temperature for most lithium batteries being between 20 and 60°C. Temperatures that are too high or too low can significantly impact the efficiency and safety of lithium batteries. For example, traditional liquid electrolytes decompose and produce gas at high temperatures (above 60°C), triggering a thermal runaway chain reaction that can easily lead to safety accidents. At low temperatures (<0°C), however, the electrolyte viscosity increases dramatically, reducing lithium ion mobility and the battery's electrochemical performance.

[0003] Therefore, most existing temperature-control materials for lithium batteries have either heating or cooling functions. When the ambient temperature is low, normal use of lithium batteries often requires heating to an appropriate temperature and then dissipating heat to control the temperature rise simultaneously. However, existing technologies often use multiple sets of temperature-control materials in a zoned manner to achieve both heating and cooling functions. However, high-temperature areas can accelerate the aging of individual components in the battery module, while low-temperature areas can limit the performance of individual components in the battery module. Furthermore, using multiple sets of temperature-control materials to achieve both cooling and heating functions simultaneously not only takes up valuable space within the lithium battery but also reduces the heating and heat dissipation efficiency of the materials themselves. Furthermore, existing battery heating methods are divided into internal heating and external heating. Internal heating has high energy conversion efficiency but requires demanding preparation conditions and a complex process. External heating devices, such as air convection heating, heat pump / heat pipe heating, and phase change material heating, are bulky and have low heat conversion efficiency, limiting their application scenarios.

[0004] On the other hand, the interlayer structure within the battery (such as the isolation layer between battery cells, modules, or different components within the battery system) needs to have good insulation properties. Otherwise, it is easy to cause short circuits, leakage, overcharging, energy loss, and other phenomena due to contact, which in turn may lead to safety issues such as thermal runaway, electric shock, and explosion. Therefore, for temperature control films that can be used in batteries, their insulation properties must be guaranteed. Summary of the Invention

[0005] In order to reduce the space occupied by temperature control materials and at the same time achieve the functions of heating and cooling, the present invention provides a temperature control film and a temperature control system and a battery using the same.

[0006] According to one aspect of the present invention, a temperature control film is provided, comprising a first functional layer and a second functional layer bonded to each other; wherein the first functional layer comprises graphene, and the second functional layer comprises fluorinated graphene and a viscous substance; the viscous substance comprises at least one of acrylate, polyurethane, and epoxy resin; in the fluorinated graphene, the content of fluorine element is a, and the content of carbon element is b; the fluorinated graphene satisfies the relationship: a / b ≥ 0.9.

[0007] The present invention cleverly arranges the first and second functional layers to provide a temperature control film with the advantages of fast heating speed, high heat conversion efficiency, strong thermal conductivity, and good insulation performance. Specifically, in the present invention, the first functional layer of graphene is first used as a heat conduction module to effectively achieve heating and thermal conductivity; secondly, the second functional layer is made to have both high thermal conductivity and high insulation performance by regulating the fluorine-carbon ratio of fluorinated graphene. In addition, by introducing at least one of acrylate, polyurethane, and epoxy resin into the second functional layer and compounding it with fluorinated graphene, the synergistic effect between the sticky substance and the fluorinated graphene can be utilized to enhance the mechanical strength, heat resistance, and insulation performance of the second functional layer. As a result, the temperature control film provided by the present invention can provide efficient heating and heat conduction at low temperatures when used in lithium batteries, and can achieve effective heat dissipation at high temperatures, thereby achieving a good temperature control effect and improving the safety of the battery. On the other hand, the temperature control film provided by the present invention has a simple structure, is easy to prepare, and is convenient for large-scale production and use. In addition, through the interlayer contact between graphene and fluorinated graphene, a good heat conduction channel is established between the temperature control membrane layers, realizing the rapid entry and exit of heat. The high insulation performance of fluorinated graphene makes up for the lack of high conductivity of graphene in battery systems, and fully utilizes the advantages of graphene with fast heating speed, low heat loss and good thermal conductivity.

[0008] Preferably, the fluorinated graphene satisfies the relationship: 0.9≤a / b≤1.2. Furthermore, by controlling the fluorine and carbon content of the fluorinated graphene, not only can the thermal conductivity and insulation effect of the temperature control film be improved, but production costs can also be controlled, thereby increasing economic benefits.

[0009] Preferably, the specific surface area of ​​graphene is 100 to 400 m 2 / g.

[0010] Preferably, the specific surface area of ​​fluorinated graphene is 200 to 350 m 2 / g.

[0011] Furthermore, the temperature control film provided by the present invention can utilize hydrogen bonding to strengthen the composite tightness between film layers by controlling the specific surface area of ​​graphene and fluorinated graphene, thereby further enhancing the stability and thermal conductivity between membranes.

[0012] Preferably, in the second functional layer, the mass ratio of fluorinated graphene to viscous substance is 0.5-5:10-20.

[0013] Furthermore, the temperature control film provided by the present invention can enhance the thermal conductivity of the temperature control film by controlling the mass ratio between the fluorinated graphene and the viscous substance in the second functional layer.

[0014] Preferably, the first functional layer also includes a polymer material, and the polymer material includes at least one of polyethylene terephthalate (PET), polyimide (PI), polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), polycarbonate (PC), polystyrene (PS), and acrylonitrile-butadiene-styrene copolymer (ABS).

[0015] Preferably, in the first functional layer, the mass content of graphene is 5 to 30%.

[0016] Furthermore, the temperature control film further includes a film layer disposed on a surface of the first functional layer remote from the second functional layer; the film layer is made of a polymer material, including at least one of polyethylene terephthalate (PET), polyimide (PI), polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), polycarbonate (PC), polystyrene (PS), and acrylonitrile-butadiene-styrene copolymer (ABS). The provision of the film layer protects the graphene in the first functional layer, reduces the likelihood of graphene oxidation, and increases the service life of the temperature control film.

[0017] Preferably, the preparation method of fluorinated graphene comprises the following steps: preparing a graphene oxide aqueous solution with a concentration of 0.2 to 5.0%, then adding a fluorinating agent thereto, and reacting at 180 to 210° C. for 18 to 24 hours under the protection of an inert gas.

[0018] Preferably, the amount of the fluorinating agent is 0.6 to 2 of the amount of graphene oxide input, calculated by molar ratio.

[0019] Preferably, the fluorinating agent includes at least one of hydrofluoric acid, ammonium bifluoride, sodium bifluoride, and potassium bifluoride.

[0020] Preferably, the temperature control film has a thickness of 20 to 100 μm; and / or the second functional layer has a thickness of 10 to 50 μm.

[0021] The second aspect of the present invention provides a temperature control system, which includes a power supply circuit and a temperature control film as described above; wherein, a potential contact point is provided on the surface of the first functional layer, and the temperature control film is connected to the power supply circuit through the potential contact point.

[0022] Preferably, the temperature control system further includes a temperature sensor and a controller, wherein the temperature sensor is responsible for real-time detection and feedback of the ambient temperature, and the controller is used to receive temperature readings and perform logical judgments based on a preset temperature range.

[0023] According to a third aspect of the present invention, a secondary battery is provided. The secondary battery includes the temperature control film or the temperature control system as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The temperature control film provided by treatment group 1A of Example 1 of the present invention;

[0025] Figure 2 The temperature control film provided by treatment group 2C in Example 3 of the present invention;

[0026] In the above drawings, the meanings of the reference numerals are as follows: 1. first functional layer; 2. second functional layer; 3. temperature control film; 4. film material. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the drawings in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0028] Example 1

[0029] Treatment group 1A

[0030] 1. Prepare the ingredients

[0031] In the treatment group 1A of this embodiment, the raw materials required for preparing the temperature control film were weighed according to the mass ratio shown in Table 1. The processing aid includes at least one of a dispersant, a promoter, and an antioxidant.

[0032] Table 1. Raw materials required for temperature control film

[0033]

[0034] 2. Preparation of temperature control film

[0035] Subsequently, the temperature control film of treatment group 1A of this embodiment was prepared according to the following method:

[0036] S1. mixing graphene with a polymer material to obtain a first mixture; mixing fluorinated graphene with a viscous substance to obtain a second mixture;

[0037] S2. The first mixture is processed by cast co-extrusion to obtain a first functional layer, and then the second mixture is coated on the surface of the first functional layer, and the second functional layer is formed after drying;

[0038] S3. The composite film is rolled up and cut into pieces to obtain a temperature-controlled film.

[0039] The thickness of the temperature control film is 50 μm, the thickness of the first functional layer is 30 μm, and the thickness of the second functional layer is 20 μm.

[0040] In this embodiment, fluorinated graphene is prepared according to the following method:

[0041] Weigh 5g of 300-mesh graphite powder and 3.8g of sodium nitrate, stir in an ice-water bath, then slowly pour in 300mL of concentrated sulfuric acid (98%), and control the reaction temperature to about 4°C. Keep stirring and slowly add 23g of potassium permanganate within one hour, controlling the reaction temperature to about 20°C. After the addition of potassium permanganate is complete, continue stirring and reacting at room temperature for 1 hour. Subsequently, slowly add 600mL of dilute sulfuric acid (5%), heat to 98°C and react for 2 hours. Cool to 60°C, add 20mL of 30% H2O2 aqueous solution, and continue stirring and reacting for 2 hours. The prepared mixed solution is centrifuged and washed until the pH value of the mixed solution reaches 4-5. The mixed solution is then centrifuged, the supernatant is removed, and the remaining mixture is ultrasonically treated for 30 minutes to obtain a graphene oxide aqueous dispersion. The graphene oxide aqueous dispersion was frozen and shaped by liquid nitrogen for 10 seconds, and the obtained product was dried in a freeze dryer to obtain honeycomb graphene oxide.

[0042] 2g of the honeycomb graphene oxide was added to 1000mL of deionized water and ultrasonically dispersed for 30 minutes. 6mL of hydrofluoric acid solution was added and ultrasonication continued for 1 hour. Under nitrogen protection, the reaction solution was transferred to a polytetrafluoroethylene autoclave and heated to 200°C for a hydrothermal reaction for 24 hours. The reaction solution was then cooled, filtered, washed with water, and dried to obtain high-content fluorinated graphene. The fluorine-carbon ratio (F:C) of the obtained fluorinated graphene was 1:1, and the specific surface area was 285m 2 / g, and the in-plane thermal conductivity is 370W·m -1 ·K -1 , the volume resistivity is 0.6*10 14 Ω·cm.

[0043] Temperature-control membranes were prepared using the recipe and method described in Example 1 for Treatment Groups 2A-3A and Comparative Groups 1A-2A, with reference to the recipe and method described in Example 1 for Treatment Group 1A. The fluorine-to-carbon ratio of the fluorinated graphene used in the recipe was used as a variable, which was achieved by adjusting the content of hydrofluoric acid in the fluorinated graphene or the content of the added honeycomb graphene oxide. The variables used to prepare the temperature-control membranes for Treatment Groups 2A-3A and Comparative Groups 1A-2A in Example 1 are shown in Table 2. Aside from the aforementioned differences, the process steps for preparing the temperature-control membranes for Treatment Groups 2A-3A and Comparative Groups 1A-2A in Example 1 remained strictly consistent with those for Treatment Group 1A in Example 1.

[0044] Table 2. Variables of each treatment group and control group in Example 1

[0045] Group F:C Treatment group 1A 1:1 Treatment group 2A 0.9:1 Treatment group 3A 1.2:1 Treatment group 4A 1.4:1 Comparative group 1A 0.7:1

[0046] Test Example 1

[0047] 1. Test subjects

[0048] The temperature control films prepared in each treatment group and the comparison group of Example 1.

[0049] 2. Test Method

[0050] (1) In-plane thermal conductivity: The temperature control film was tested using a laser thermal conductivity meter according to ISO 2207-2 "Plastics Determination of thermal conductivity and thermal diffusivity-Part 2: Transient plane heat source (hot disc) method". During the test, the probe was placed in the middle of the sample to be tested to ensure that the sample to be tested and the probe were in close contact. Each sample to be tested was tested three times, and the average value was taken.

[0051] (2) Volume resistivity: Use a high resistance meter to test the volume resistivity of the temperature control film. For specific test standards, refer to ASTM D257.

[0052] 3. Test results and analysis

[0053] In current application requirements, the general industry generally requires the in-plane thermal conductivity of the thermal conductive film to be greater than 0.5W·m -1 ·K -1 The volume resistivity requirement is higher than 1*10 12 Ω·cm.

[0054] Combined with the test results of this test example (as shown in Table 3), it can be seen from the test results that as the fluorine content in the fluorinated graphene increases, the thermal conductivity of the temperature control film also decreases, while the volume resistivity increases. This shows that as the fluorine-carbon ratio in the fluorinated graphene increases, its thermal conductivity decreases, but its insulation performance increases. This may be because fluorine atoms destroy the perfect lattice structure of graphene, forming sp 3 Hybridized carbon-fluorine bonds lead to enhanced phonon scattering, which inhibits the efficiency of heat transfer (graphene has high thermal and electrical conductivity).

[0055] For the temperature control film, the second functional layer undertakes the functions of insulation and heat conduction, so it is necessary to achieve a dynamic balance between thermal conductivity and insulation performance. If the fluorine-carbon ratio is too low (i.e., the fluorine content is insufficient), although the second functional layer can retain a relatively high thermal conductivity, the insulation performance is difficult to meet the requirements of high-voltage application scenarios; conversely, if the fluorine-carbon ratio is too high, although the insulation performance is excellent, the thermal conductivity is significantly reduced. Furthermore, the present application can improve the thermal conductivity and insulation performance of the temperature control film by controlling the fluorine-carbon ratio a / b to 0.9 to 1.2:1, thereby maintaining a dynamic balance between thermal conductivity and insulation performance.

[0056] Table 3. Test results

[0057] Group <![CDATA[In-plane thermal conductivity / (W·m -1 ·K -1 )]]> Volume resistivity / (Ω·cm) Treatment group 1A 52 <![CDATA[1.2*10 14 ]]> Treatment group 2A 57 <![CDATA[0.3*10 14 ]]> Treatment group 3A 42 <![CDATA[1.7*10 14 ]]> Treatment group 4A 25 <![CDATA[1.9*10 14 ]]> Comparative group 1A 64 <![CDATA[1.1*10 10 ]]>

[0058] Example 2

[0059] The temperature control film of treatment group 1B of this embodiment 2 was prepared strictly according to the formula and method provided in embodiment 1.

[0060] In Example 2, treatment groups 2B-7B and comparative groups 1B-2B prepared temperature-control films using the recipe and method provided in treatment group 1B, with the viscous material used in the recipe and its ratio to fluorinated graphene as variables. The variables used to prepare the temperature-control films in treatment groups 2B-7B and comparative groups 1B-2B of Example 2 are shown in Table 4. Aside from the aforementioned differences, the process steps for preparing the temperature-control films in treatment groups 2B-7B and comparative groups 1B-2B of Example 2 were strictly consistent with those in treatment group 1B of Example 2. In treatment group 4B, the mass ratio of acrylate to epoxy resin was 1:1.

[0061] Table 4. Variables of each treatment group and control group in Example 1

[0062] Group sticky substances Fluorinated graphene: the sticky stuff Treatment group 1B Acrylate 8:90 Treatment group 2B polyurethane 8:90 Treatment group 3B epoxy resin 8:90 Treatment group 4B Acrylate, epoxy resin 8:90 Treatment group 5B Acrylate 5:10 Treatment group 6B Acrylate 1:40 Treatment group 7B Acrylate 1:50 Control group 1B polyvinyl alcohol 8:90 Control group 2B PET 8:90

[0063] Test Example 2

[0064] 1. Test subjects

[0065] The temperature control films prepared in each treatment group and the comparison group of Example 2.

[0066] 2. Test Method

[0067] This test example is tested with reference to the test method provided in Test Example 1.

[0068] 3. Test results and analysis

[0069] The test results of this test example are shown in Table 5. Among them, the test results of treatment groups 1B to 4B and comparison groups 1B to 2B show that the choice of viscous material will affect the mechanical properties, thermal conductivity and insulation properties of the temperature control film. This may be because there is a synergistic effect between acrylate, polyurethane, epoxy resin and fluorinated graphene. Furthermore, in treatment group 4B, the insulation performance of the temperature control film can be improved by preparing the second functional layer with acrylic resin and epoxy resin. The viscous material used in comparison group 1B is polyvinyl alcohol, and the resistivity of ordinary polyvinyl alcohol is about 3.1 to 3.8×10 9 Ω·cm, thermal conductivity is generally 0.2W·m -1 ·K -1 About, by introducing fluorinated graphene and matching it with the first functional layer to prepare the temperature control film, although its thermal conductivity and resistivity are improved, it still does not meet the performance requirements required by the application of this application.

[0070] For example, the polar groups of acrylates (such as carboxylic acid groups) form strong interfacial bonds with fluorine atoms on the surface of fluorinated graphene through hydrogen bonds or van der Waals forces, effectively reducing interfacial voids and enhancing the material's cohesion. On the other hand, the flexible chain segments of acrylates can fill the pores between fluorinated graphene sheets, forming continuous thermal conduction channels and achieving synergistic optimization of thermal conductivity and insulation properties.

[0071] As for polyurethane, its soft segments (such as polyether chains) form dynamic covalent bonds (such as hydrogen bonds and coordination bonds) with fluorinated graphene, which can improve the bending fatigue performance of the temperature control membrane and increase its service life. In addition, the hard segments of polyurethane (such as isocyanate groups) can form chemical crosslinks with the fluorinated carbon chains on the surface of fluorinated graphene, reducing phonon scattering and thus enhancing the thermal conductivity of the temperature control membrane.

[0072] The three-dimensional cross-linked network of epoxy resin can wrap the fluorinated graphene sheets, which can block the volatilization of fluorine atoms at high temperatures and inhibit local discharge between the fluorinated graphene sheets, thereby improving the insulation performance of the temperature control film.

[0073] Furthermore, test data from treatment groups 1B and 5B-7B demonstrates that by adjusting the ratio of fluorocarbon graphene to the viscous material, the thermal conductivity and insulation properties of the temperature-control membrane can be further enhanced, effectively dissipating heat while improving battery safety. In treatment group 7B, the lower amount of fluorographene resulted in a lower resistivity.

[0074] Table 5. Test results

[0075] Group <![CDATA[In-plane thermal conductivity / (W·m -1 ·K -1 )]]> Volume resistivity / (Ω·cm) Treatment group 1B 52 <![CDATA[1.2*10 14 ]]> Treatment group 2B 49 <![CDATA[0.9*10 14 ]]> Treatment group 3B 50 <![CDATA[1.5*10 14 ]]> Treatment group 4B 50 <![CDATA[1.4*10 14 ]]> Treatment group 5B 158 <![CDATA[2.6*10 14 ]]> Treatment group 6B 12 <![CDATA[1.1*10 12 ]]> Treatment group 7B 2 <![CDATA[1.5*10 11 ]]> Control group 1B 50 <![CDATA[1.3*10 11 ]]> Control group 2B 43 <![CDATA[3.5*10 11 ]]>

[0076] Example 3

[0077] Treatment group 1C

[0078] The temperature control film of treatment group 1C of this embodiment 3 was prepared strictly according to the formula and method provided in embodiment 1.

[0079] Treatment group 2C

[0080] This treatment group prepared the temperature control film using the formula and method provided by treatment group 1C. The temperature control film provided in this treatment group also includes film materials. Specifically, the steps for preparing the temperature control film in this treatment group are:

[0081] S1. mixing graphene with a polymer material to obtain a first mixture; mixing fluorinated graphene with a viscous substance to obtain a second mixture;

[0082] S2. The masterbatch PET and the first mixture are co-extruded to obtain a composite film and a first functional layer, and then the second mixture is applied to the surface of one side near the first functional layer, and the second functional layer is formed after drying;

[0083] S3. The composite film is rolled up and slit to obtain a temperature control film, wherein the temperature control film has a thickness of 75 μm, the first functional layer has a thickness of 30 μm, and the second functional layer has a thickness of 20 μm.

[0084] Control group 1C

[0085] The temperature control film of this comparative group was prepared according to the formula and method provided by treatment group 1C. Specifically, the steps for preparing the temperature control film of this treatment group were as follows:

[0086] S1. Mixing graphene, fluorinated graphene and polymer materials to obtain a first mixture

[0087] S2. The first mixture is processed by cast co-extrusion to obtain a first functional layer, and then a viscous material is coated on the surface of the first functional layer, and a second functional layer is formed after drying;

[0088] S3. Coating the surface of the second functional layer. Roll up and slit the composite film to obtain a temperature control film.

[0089] Control group 2C

[0090] The temperature control film of this comparative group was prepared according to the formula and method provided by treatment group 1C. Specifically, the steps for preparing the temperature control film of this treatment group were as follows:

[0091] S1. mixing graphene, fluorinated graphene and a viscous substance to obtain a second mixture;

[0092] S2. The polymer material is processed by cast co-extrusion to obtain a first functional layer, and then the second mixture is coated on the surface of the first functional layer, and the second functional layer is formed after drying;

[0093] S3. The composite film is rolled up and cut into pieces to obtain a temperature-controlled film.

[0094] Control group 3C

[0095] This control group used the same recipe and method as treatment group 1C to prepare the temperature-control film. Unlike treatment group 1C, this control group did not incorporate graphene into the first functional layer of the temperature-control film. Other than these differences, this control group remained strictly consistent with treatment group 1C.

[0096] Control group 4C

[0097] This control group used the same recipe and method as treatment group 1C to prepare a temperature-control film. Unlike treatment group 1C, this control group did not incorporate fluorinated graphene into the second functional layer of the temperature-control film. Other than these differences, this control group remained strictly consistent with treatment group 1C.

[0098] Test Example 3

[0099] 1. Test subjects

[0100] The temperature control films prepared in each treatment group and the comparison group of Example 3.

[0101] 2. Test Method

[0102] This test example is tested with reference to the test method provided in Test Example 1.

[0103] 3. Test results and analysis

[0104] The test results of this test case are shown in Table 6.

[0105] The test results for Treatment Groups 1C and 2C indicate that the inclusion of the membrane material within the temperature-control membrane significantly reduces the risk of graphene oxidation in the first functional layer through a triple mechanism of physical isolation, chemical stabilization, and mechanical support, thereby extending the product's service life. In Treatment Group 2C, due to the inclusion of the membrane material, the in-plane thermal conductivity and volume resistivity tested were reduced, but the device still maintained good thermal conductivity and insulation properties.

[0106] From the data of comparison groups 1C to 2C, it can be seen that when fluorinated graphene is mixed with graphene to prepare the temperature control film, the thermal conductivity or insulation performance of the temperature control film is reduced. Based on the data of comparison groups 3C to 4C, it can be seen that in the temperature control film provided by the present invention, graphene and fluorinated graphene are indispensable. Although the two are in different interlayer structures, they provide different functional supports for the temperature control film. Specifically, graphene has good electrical and thermal conductivity, so it can realize the function of electric heating in the first functional layer, and due to the sp 2 The hybrid structure gives it an ultra-high in-plane thermal conductivity (theoretical value 5300 W·m -1 ·K -1 ), which can quickly transfer heat and achieve uniform temperature control; while the fluorinated graphene in the second functional layer can, on the one hand, enhance the insulation of the temperature control film and block current conduction; on the other hand, due to the hydrogen bonding between it and the viscous substance, it can optimize the interlayer heat conduction path, thereby improving the overall thermal conductivity of the temperature control film.

[0107] Table 6. Test results

[0108] Group <![CDATA[In-plane thermal conductivity / (W·m -1 ·K -1 )]]> Volume resistivity / (Ω·cm) Treatment group 1C 52 <![CDATA[1.2*10 14 ]]> Treatment group 2C 16 <![CDATA[0.9*10 14 ]]> Control group 1C 0.8 <![CDATA[1.5*10 10 ]]> Control group 2C 0.2 <![CDATA[1.4*10 10 ]]> Control group 3C 0.2 <![CDATA[1.1*10 10 ]]> Control group 4C 0.2 <![CDATA[1.3*10 10 ]]>

[0109] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A temperature control film, characterized in that: The temperature control film includes a first functional layer and a second functional layer laminated to each other; wherein the first functional layer includes graphene, and the second functional layer includes fluorinated graphene and a viscous substance; The adhesive material includes at least one of acrylate, polyurethane, and epoxy resin; In the fluorinated graphene, the content of fluorine element is a, and the content of carbon element is b; the fluorinated graphene satisfies the relationship: a / b≥0.

9.

2. The temperature control film according to claim 1, characterized in that: The fluorinated graphene satisfies the relationship: 0.9≤a / b≤1.

2.

3. The temperature control film according to claim 1, characterized in that: In the second functional layer, the weight ratio of the fluorinated graphene to the viscous substance is 0.5-5:10-20.

4. The temperature control film according to claim 1, wherein: The first functional layer further comprises a polymer material, and the polymer material comprises at least one of polyethylene terephthalate, polyimide, polyvinyl chloride, polypropylene, polyethylene, polycarbonate, polystyrene, and acrylonitrile-butadiene-styrene copolymer.

5. The temperature control film according to claim 1, wherein: In the first functional layer, the mass content of the graphene is 5 to 30%.

6. The temperature control film according to claim 1, wherein: The preparation method of fluorinated graphene includes the following steps: preparing a graphene oxide aqueous solution with a concentration of 0.2-5.0%, then adding a fluorinating agent thereto, and reacting at 180-210° C. for 18-24 hours under the protection of an inert gas.

7. The temperature control film according to claim 6, characterized in that: Calculated by molar ratio, the amount of the fluorinating agent is 0.6 to 2 of the amount of the graphene oxide input.

8. The temperature control film according to any one of claims 1 to 7, characterized in that: The temperature control film has a thickness of 20 to 100 μm; and / or the second functional layer has a thickness of 10 to 50 μm.

9. A temperature control system, characterized in that: The temperature control system includes a power supply circuit and the temperature control film according to any one of claims 1 to 8; wherein, a potential contact point is provided on the surface of the first functional layer, and the temperature control film is connected to the power supply circuit through the potential contact point.

10. A secondary battery, characterized in that: The secondary battery comprises the temperature control film according to any one of claims 1 to 8, or the temperature control system according to claim 9.

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