A phase change composite material with three-dimensional continuous nanoskeleton, a preparation method and a battery thermal management system

Abstract

The application belongs to the technical field of new energy automobile battery thermal management, and particularly relates to a phase change composite material with a three-dimensional continuous nanometer skeleton, a preparation method and a battery thermal management system. The phase change composite material with the three-dimensional continuous nanometer skeleton provided by the application improves the anti-leakage ability and anti-deformation ability of the existing phase change material, and has excellent phase change temperature, latent heat value and thermal conductivity, thereby solving the technical problems that the phase change material in the existing battery thermal management system is prone to leakage and the module is deformed.

Description

Technical Field

[0001] This application belongs to the field of new energy vehicle battery thermal management technology, and in particular relates to a phase change composite material with a three-dimensional continuous nanoframework, its preparation method, and a battery thermal management system. Background Technology

[0002] Lithium-ion battery packs and other power battery packs, as the power system of new energy vehicles, can alleviate the problem of fossil fuel shortages.

[0003] Safety issues with the power battery packs of new energy electric vehicles have limited the promotion of these vehicles. A major reason for these safety issues is the thermal abuse of the battery modules. During charging and discharging, the conversion between electrical and chemical energy generates a large amount of heat. If this heat cannot be dissipated in time and accumulates inside the battery, it can lead to localized overheating of the battery module, a sharp decline in battery performance, and in extreme cases, even spontaneous combustion and explosion. Currently, phase change materials are typically incorporated into the battery thermal management system to control the temperature and temperature distribution of the power battery module.

[0004] However, the phase change materials such as blended polyethylene, polystyrene, styrene-butadiene rubber, and epoxy resin used in current battery thermal management systems cannot effectively suppress the slow migration of liquid phase change materials. This leads to safety issues such as phase change material leakage and module deformation during long-term use, which is not conducive to the large-scale application of phase change material battery thermal management systems in new energy vehicles. Summary of the Invention

[0005] In view of this, this application provides a phase change composite material with a three-dimensional continuous nanoframework, a preparation method thereof, and a battery thermal management system, to solve the technical problems of easy leakage of phase change materials and module deformation in existing battery thermal management systems.

[0006] The first aspect of this application provides a phase change composite material with a three-dimensional continuous nanoframework, including a three-dimensional continuous nanoframework and a phase change material;

[0007] The three-dimensional continuous nanoframework includes stacked nanopores;

[0008] The nanopores adsorb the phase change material.

[0009] Preferably, the pore size of the nanopores is 8–12 nm.

[0010] Preferably, the material of the three-dimensional continuous nanoframework is phenolic resin;

[0011] The phase change material is selected from at least one of polyethylene glycol, paraffin wax, octadecyl alcohol, n-octadecane, n-docosahexadecane, and octadecyl acrylate;

[0012] The phase change material also includes thermally conductive additives;

[0013] The thermally conductive additive is selected from expanded graphite.

[0014] Preferably, the phase change composite material with a three-dimensional continuous nanoskeleton comprises, by mass, 10 to 40 parts by mass of a three-dimensional continuous nanoskeleton, 50 to 100 parts by mass of a phase change material, and 3 to 10 parts by mass of a thermally conductive additive.

[0015] Preferably, the phase change composite material with a three-dimensional continuous nanoframework comprises 35 parts by mass of a three-dimensional continuous nano phenolic resin framework, 30 parts by mass of polyethylene glycol, 30 parts by mass of octadecyl alcohol, and 5 parts by mass of expanded graphite, calculated in parts by mass.

[0016] The molecular weight of the polyethylene glycol is 1500.

[0017] The second aspect of this application provides a method for preparing a phase change composite material with a three-dimensional continuous nanoframework. This method is simple and can produce the aforementioned phase change composite material with a three-dimensional continuous nanoframework in large quantities. The preparation method includes the following steps:

[0018] Step S1: Stir the phase change material, reactant monomer and catalyst until they are mixed evenly to obtain the phase change composite material precursor;

[0019] Step S2: In-situ polymerization of the phase change composite material precursor is carried out to obtain a phase change composite material with a three-dimensional continuous nanoframework.

[0020] Preferably, in step S2, the in-situ polymerization temperature is 90–100°C and the time is 6–8 days.

[0021] Preferably, in step S1, the reaction monomers are resorcinol and furfural;

[0022] The catalyst is sodium hydroxide;

[0023] The resorcinol is 25 moles, furfural is 50 moles, and sodium hydroxide is 1 mole, calculated in molar parts.

[0024] Preferably, in step S1, after stirring and mixing the phase change material, the reactive monomer and the catalyst, the step further includes: adding a thermally conductive additive and stirring.

[0025] When adding the thermally conductive additive, the stirring speed is 1000-1500 r / min, the time is 20-60 min, and the temperature is 70-90℃.

[0026] Preferably, in step S1, the stirring speed of the phase change material, the reaction monomer, and the catalyst is 200-300 r / min.

[0027] Preferably, in step S2, in-situ polymerization involves placing the phase change composite material precursor in a mold for in-situ polymerization.

[0028] A third aspect of this application provides a battery thermal management system, which includes a battery module and the aforementioned phase change composite material with a three-dimensional continuous nanoframework.

[0029] The battery module is embedded in the phase change composite material with a three-dimensional continuous nanoframework.

[0030] In summary, this application provides a phase change composite material with a three-dimensional continuous nanoskeleton, a preparation method thereof, and a battery thermal management system. The phase change composite material with a three-dimensional continuous nanoskeleton includes a three-dimensional continuous nanoskeleton and a phase change material. Nanopores are stacked on the three-dimensional continuous nanoskeleton. These nanopores have a physical adsorption effect on the liquid phase change material in the molten state according to the principle of capillary condensation. At the same time, the nanopores also have a physical confinement ability for the liquid phase change material in the molten state, thereby improving the leakage resistance of the phase change composite material. Furthermore, the three-dimensional continuous nanoskeleton can serve as a supporting structure, endowing the phase change composite material with mechanical properties, thereby solving the technical problems of easy leakage and module deformation of phase change materials in existing battery thermal management systems. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the preparation method of phase change composite material with three-dimensional continuous nanoframework provided in Examples 1-4 of this application;

[0033] Figure 2 Differential scanning calorimetry image of phase change composite material with three-dimensional continuous nanoframework provided in Embodiment 1 of this application;

[0034] Figure 3 Differential scanning calorimeter image of a phase change composite material with a three-dimensional continuous nanoframework provided in Embodiment 2 of this application;

[0035] Figure 4 Differential scanning calorimetry image of phase change composite material with three-dimensional continuous nanoframework provided in Embodiment 3 of this application;

[0036] Figure 5 Differential scanning calorimetry image of phase change composite material with three-dimensional continuous nanoframework provided in Example 4 of this application;

[0037] Figure 6 A scanning electron microscope image of a phase change composite material with a three-dimensional continuous nanoframework provided in Example 4 of this application;

[0038] Figure 7 Nitrogen adsorption diagram of the phase change composite material with a three-dimensional continuous nanoframework provided in Example 4 of this application;

[0039] Figure 8 Mass loss curve of phase change composite material with three-dimensional continuous nanoframework provided in Example 4 of this application after heating at 60°C for 12 hours;

[0040] Figure 9 A schematic diagram of the shape stability test of the phase change composite material with a three-dimensional continuous nanoframework provided in Example 4 of this application after heating at 60°C for 12 hours;

[0041] Figure 10 Temperature change curves of the battery thermal management system provided in Embodiment 6 of this application at a 1C charging rate and a 0.5C discharging rate;

[0042] Figure 11 Temperature change curves of the battery thermal management system provided in Embodiment 6 of this application at 1C charging rate and 1C discharging rate;

[0043] Figure 12 Temperature change curves of the battery thermal management system provided in Embodiment 6 of this application at 1C charging rate and 2C discharging rate. Detailed Implementation

[0044] This application provides a phase change composite material with a three-dimensional continuous nanoframework, its preparation method, and a battery thermal management system, which solves the technical problems of easy leakage of phase change materials and module deformation in existing battery thermal management systems.

[0045] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] Example 1

[0047] Example 1 of this application provides a first method for preparing phase change composite materials with a three-dimensional continuous nanoframework. Compared with the existing preparation process of phase change microcapsules, this preparation process is simple and can prepare phase change composite materials with a three-dimensional continuous nanoframework in large batches. The preparation method includes the step of preparing a phase change composite material precursor and the step of in-situ polymerization.

[0048] The steps for preparing the phase change composite material precursor include: polyethylene glycol (PEG1500) with a molecular weight of 1500 is poured into an 80°C constant temperature water bath according to a mass ratio of 60:35:5 for the phase change material polyethylene glycol, the phenolic resin three-dimensional continuous nanoframework, and the thermally conductive additive graphite. After the PEG1500 is completely melted, 25 moles of resorcinol, 50 moles of furfural, and 1 mole of sodium hydroxide are added. The mixture is magnetically stirred at 270 r / min until the resorcinol and sodium hydroxide are completely dissolved. The mixture is then transferred to an 80°C oil bath, and expanded graphite is slowly added in batches while mechanically stirred at 1200 r / min for 40 min to obtain the phase change composite material precursor.

[0049] The in-situ polymerization steps include: pouring the phase change composite material precursor into a mold while it is still hot and sealing it; placing it in an oven at 95°C for in-situ reaction for 7 days; and then demolding it after the reaction is complete to obtain a composite phase change material with a three-dimensional continuous nanoframework.

[0050] Example 2

[0051] Example 2 of this application provides a second method for preparing a phase change composite material with a three-dimensional continuous nanoframework. The preparation method includes the steps of preparing a phase change composite material precursor and in-situ polymerization.

[0052] The steps for preparing the phase change composite material precursor include: polyethylene glycol (PEG1500) with a molecular weight of 1500 is poured into an 80°C constant temperature water bath according to a mass ratio of 70:25:5 for the phase change material polyethylene glycol, the phenolic resin three-dimensional continuous nanoframework, and the thermally conductive additive graphite. After the PEG1500 is completely melted, 25 moles of resorcinol, 50 moles of furfural, and 1 mole of sodium hydroxide are added. The mixture is magnetically stirred at 270 r / min until the resorcinol and sodium hydroxide are completely dissolved. The mixture is then transferred to an 80°C oil bath, and expanded graphite is slowly added in batches while mechanically stirred at 1200 r / min for 40 min to obtain the phase change composite material precursor.

[0053] The in-situ polymerization steps include: pouring the phase change composite material precursor into a mold while it is still hot and sealing it; placing it in an oven at 95°C for in-situ reaction for 7 days; and then demolding it after the reaction is complete to obtain a composite phase change material with a three-dimensional continuous nanoframework.

[0054] Example 3

[0055] Example 3 of this application provides a third method for preparing phase change composite materials with a three-dimensional continuous nanoframework. The preparation method includes the steps of preparing a phase change composite material precursor and in-situ polymerization.

[0056] The steps for preparing the phase change composite material precursor include: polyethylene glycol (PEG1500) with a molecular weight of 1500 is poured into a constant temperature water bath at 80°C according to the mass ratio of the phase change material polyethylene glycol, the phenolic resin three-dimensional continuous nanoframework, and the thermally conductive additive graphite in the phase change composite material of 80:15:5. After the PEG1500 is completely melted, 25 moles of resorcinol, 50 moles of furfural, and 1 mole of sodium hydroxide are added. The mixture is magnetically stirred at 270 r / min until the resorcinol and sodium hydroxide are completely dissolved. The mixture is then transferred to an oil bath at 80°C, and expanded graphite is slowly added in batches while mechanically stirred at 1200 r / min for 40 min to obtain the phase change composite material precursor.

[0057] The in-situ polymerization steps include: pouring the phase change composite material precursor into a mold while it is still hot and sealing it; placing it in an oven at 95°C for in-situ reaction for 7 days; and then demolding it after the reaction is complete to obtain a composite phase change material with a three-dimensional continuous nanoframework.

[0058] Example 4

[0059] Example 4 of this application provides a fourth method for preparing a phase change composite material with a three-dimensional continuous nanoframework. The preparation method includes the steps of preparing a phase change composite material precursor and in-situ polymerization.

[0060] The steps for preparing the phase change composite material precursor include: According to the mass ratio of the phase change material polyethylene glycol, octadecyl alcohol, phenolic resin, and thermally conductive additive graphite in the three-dimensional continuous nanoskeleton phase change composite material, PEG1500 (molecular weight 1500) is poured into an 80°C constant temperature water bath. After the PEG1500 is completely melted, 25 moles of resorcinol, 50 moles of furfural, and 1 mole of sodium hydroxide are added. The mixture is magnetically stirred at 270 r / min until the resorcinol and sodium hydroxide are completely dissolved. The mixture is then transferred to an 80°C oil bath, and expanded graphite is slowly added in batches while mechanically stirred at 1200 r / min for 40 min to obtain the phase change composite material precursor.

[0061] The in-situ polymerization steps include: pouring the phase change composite material precursor into a mold while it is still hot and sealing it; placing it in an oven at 95°C for in-situ reaction for 7 days; and then demolding it after the reaction is complete to obtain a composite phase change material with a three-dimensional continuous nanoframework.

[0062] Example 5

[0063] Given the shortcomings of existing battery thermal management systems using phase change materials such as blended polyethylene, polystyrene, styrene-butadiene rubber, and epoxy resin, which are prone to phase change material leakage and module deformation during use, Embodiment 5 of this application provides a phase change composite material with a three-dimensional continuous nanoframework. The phase change material consists of a three-dimensional continuous nanoframework and the phase change material itself. The three-dimensional continuous nanoframework forms nanopores, and the phase change material is adsorbed by the nanopores. A scanning electron microscope image of the phase change composite material with a three-dimensional continuous nanoframework is shown below. Figure 6 As shown, from Figure 6 Nanopores formed by stacked three-dimensional continuous nanoframeworks can be observed. These nanopores have a physical adsorption capacity for phase change materials in the molten state based on capillary condensation, which enhances the leakage resistance of the phase change composite material. At the same time, the nanopores formed by stacked three-dimensional continuous nanoframeworks can exert a great physical confinement effect on the flow of phase change materials in the molten state. Furthermore, the three-dimensional continuous nanoframeworks can serve as a supporting structure, endowing the phase change composite material with mechanical properties. As a result, the three-dimensional continuous nanoframeworks provided in this application are less prone to leakage and module deformation, achieving long-term and stable temperature control and significantly reducing the risk of thermal hazards during the use of power battery modules for new energy vehicles.

[0064] Furthermore, for the pore size of the nanopores formed by stacking three-dimensional continuous nanoframeworks, this application preferably has a pore size of 8 to 12 nm, and more preferably 10 nm. The smaller the pore size of the nanopores, the stronger the adsorption effect on the phase change material in the molten state. Therefore, a pore size of about 10 nm is beneficial to further improve the leakage resistance of the phase change composite material.

[0065] Furthermore, regarding the phase change material in the phase change composite material, this application uses at least one of polyethylene glycol, paraffin wax, octadecyl alcohol, n-octadecane, n-docosahexadecane, and octadecyl acrylate. The three-dimensional continuous nanoframework used in this application is a three-dimensional continuous nanoframework made of phenolic resin. At the same time, the phase change material in the phase change composite material also includes thermally conductive additives such as expanded graphite, which are beneficial to improving the thermal conductivity of the phase change composite material.

[0066] Furthermore, regarding the proportions of each component in the phase change composite material, this application uses 10-40 parts by mass of a three-dimensional continuous nano-framework, 50-100 parts by mass of the phase change material, and 3-10 parts by mass of a thermally conductive additive; more preferably, a phase change composite material composed of 35 parts by mass of a three-dimensional continuous nano-phenolic resin framework, 30 parts by mass of polyethylene glycol, 30 parts by mass of octadecyl alcohol, and 5 parts by mass of expanded graphite is used. The phase change composite material with this proportion not only has a low mass loss rate and is not easily deformed, but also has excellent phase change temperature, latent heat value, and thermal conductivity.

[0067] Furthermore, regarding the components of the three-dimensional continuous nano-phenolic resin framework, calculated in molar parts, the resin used in this application is prepared by adding 25 molar parts of resorcinol, 50 molar parts of furfural, and 1 molar part of sodium hydroxide. This proportion of phenolic resin components is beneficial for forming a stable three-dimensional continuous nano-framework and improving the performance of phase change materials.

[0068] Example 6

[0069] Embodiment 6 of this application provides a battery thermal management system, which includes a composite phase change material with a three-dimensional continuous nanoframework and a battery module as provided in Embodiments 1-5; the battery module is an existing lithium-ion battery or plasma battery module, and the structure between the battery module and the composite phase change material with a three-dimensional continuous nanoframework is an existing structure, in which the composite phase change material with a three-dimensional continuous nanoframework embedded in the battery module is wrapped.

[0070] For Embodiment 6 of this application, a composite phase change material with a three-dimensional continuous nanoskeleton in a battery thermal management system is provided. This application preferably uses a phase change composite material composed of 35 parts by mass of a three-dimensional continuous nano phenolic resin skeleton, 30 parts by mass of polyethylene glycol, 30 parts by mass of octadecyl alcohol, and 5 parts by mass of expanded graphite.

[0071] Experimental Example 1

[0072] Experimental Example 1 of this application tests the performance of the phase change composite material with a three-dimensional continuous nanoframework prepared by the preparation methods described in Examples 1-4 and the battery thermal management system provided in Example 6.

[0073] The differential scanning calorimeter images of the phase change composite materials with a three-dimensional continuous nanoframework provided in Examples 1-4 are shown below. Figure 2-5 As shown, for Figure 2-5 The latent heat of phase change of the phase change composite materials with a three-dimensional continuous nanoframework provided in Examples 1-4 was calculated to be 52.01 J·g by integrating the endothermic peak of the DSC curves shown. -1 68.71 J·g -1 98.93 J·g -1 and 107.18 J·g -1 The latent heat of phase change in phase change materials is related to their energy storage efficiency. The phase change composite material with a three-dimensional continuous nanoframework provided in Example 4 has the largest latent heat of phase change, which indicates that the phase change composite material composed of 35 parts by mass of a three-dimensional continuous nano phenolic resin framework, 30 parts by mass of polyethylene glycol, 30 parts by mass of octadecyl alcohol, and 5 parts by mass of expanded graphite has an excellent latent heat of phase change.

[0074] Further testing was conducted on the structure of the phase change composite material with a three-dimensional continuous nanoframework provided in Example 4, and its scanning electron microscope image and nitrogen adsorption image are shown below. Figure 6-7 As shown, from Figure 6-7 As can be seen, the nanopores of the phase change composite material with a three-dimensional continuous nanoskeleton provided in Example 4 have a pore size of about 10 nm. According to the principle of capillary condensation, the smaller the pore size, the stronger the adsorption effect on the phase change material in the molten state, and the stronger the anti-leakage ability of the phase change composite material. Furthermore, the nanopores formed by the stacked phenolic resin nanoskeleton can exert a great physical confinement effect on the flow of the phase change material in the molten state, giving the phase change composite material shape stability under heating conditions.

[0075] The results of the anti-leakage and anti-deformation performance tests on the phase change composite material with a three-dimensional continuous nanoframework provided in Example 4 are as follows: Figure 8-9 As shown; from Figure 8-9 The test results show that the phase change composite material provided in Example 4 has a mass loss rate of only 0.16 wt% after heating at 60°C for 12 hours, and its shape remains unchanged after heating at 60°C for 12 hours. Observation of the filter paper used to hold the sample reveals almost no leakage marks on the filter paper. Considering that polyethylene glycol, as a hydrophilic material, inevitably absorbs moisture from the air, the evaporation of moisture during heating will cause mass loss. This indicates that the leakage loss of the phase change composite material with a three-dimensional continuous nanoframework provided in Example 4 is almost negligible during heating. This demonstrates the excellent anti-leakage performance and shape stability of the phase change composite material under heat, exhibiting excellent anti-leakage and anti-deformation properties, which can solve the defects of easy leakage and module deformation of phase change materials in existing battery thermal management systems.

[0076] Furthermore, as described in Example 6, the phase change composite material with a three-dimensional continuous nanoframework provided in Example 4 was combined with a battery module to form a simplified battery thermal management system. The temperature control capability of the phase change composite material in the battery thermal management system was tested, and the test results are as follows: Figure 10-12 As shown, from Figure 10-12 It can be seen that, under different charge and discharge rates, the phase change composite material with a three-dimensional continuous nanoframework provided in this application can maintain the maximum temperature of the battery between 41.15 and 46.82℃, and the temperature difference between 2.12 and 2.76℃. This indicates that the phase change composite material in the battery thermal management system provided in this application has good heat dissipation effect and good temperature uniformity performance, and the phase change composite material has excellent temperature control capability.

[0077] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A battery thermal management system, characterized by, The battery module and the phase change composite material with three-dimensional continuous nanoskeleton are provided. The battery module is embedded in the phase change composite material with three-dimensional continuous nanoskeleton. The preparation method of the phase change composite material with three-dimensional continuous nanoskeleton comprises the following steps: In step S1, the phase change material, the reaction monomer and the catalyst are stirred to be uniformly mixed to obtain a phase change composite material precursor. In step S2, the phase change composite material precursor is subjected to in-situ polymerization to obtain the phase change composite material with three-dimensional continuous nanoskeleton. The phase change composite material with three-dimensional continuous nanoskeleton comprises a three-dimensional continuous nanoskeleton and a phase change material, the three-dimensional continuous nanoskeleton comprises stacked nanoholes, and the nanoholes adsorb the phase change material. The reaction monomer is resorcinol and furfural. The phase change material is selected from at least one of polyethylene glycol, paraffin, octadecanol, n-octadecane, n-docosane and octadecyl acrylate. In step S1, the catalyst is sodium hydroxide. In terms of molar parts, the resorcinol is 25 molar parts, the furfural is 50 molar parts, and the sodium hydroxide is 1 molar part.

2. The battery thermal management system of claim 1, wherein, The pore size of the nanohole is 8-12 nm.

3. The battery thermal management system of claim 1, wherein, The phase change material further comprises a heat-conducting additive, expanded graphite.

4. The battery thermal management system of claim 3, wherein, In terms of mass parts, the phase change composite material with three-dimensional continuous nanoskeleton comprises 10-40 mass parts of three-dimensional continuous nanoskeleton, 50-100 mass parts of phase change material and 3-10 mass parts of heat-conducting additive.

5. The battery thermal management system of claim 4, wherein, In terms of mass parts, the phase change composite material with three-dimensional continuous nanoskeleton comprises 35 mass parts of three-dimensional continuous nanoskeleton, 30 mass parts of polyethylene glycol and 30 mass parts of octadecanol, and 5 mass parts of expanded graphite. The molecular weight of the polyethylene glycol is 1500.

6. The battery thermal management system of claim 1, wherein, In step S2, the temperature of the in-situ polymerization is 90-100 ℃, and the time is 6-8 days.

7. The battery thermal management system of claim 1, wherein, In step S1, after the phase change material, the reaction monomer and the catalyst are stirred and mixed, the method further comprises the following step: adding a heat-conducting additive and stirring. The stirring speed of adding the heat-conducting additive and stirring is 1000-1500 r / min, the time is 20-60 min, and the temperature is 70-90 ℃.

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