A thermally conductive insulating coating, method of manufacture and lithium ion battery module

Abstract

The present disclosure relates to the technical field of coating, in particular to a heat-conducting insulating coating, a preparation method and a lithium ion battery module. The material of the heat-conducting insulating coating comprises one-dimensional heat-conducting nanofiber coated insulating particles; the one-dimensional heat-conducting nanofiber comprises a first polymer and a heat-conducting agent dispersed in the first polymer; and the material of the insulating particles comprises a second polymer. The heat-conducting insulating coating disclosed in the present disclosure overcomes the problem of low thermal conductivity caused by discontinuous heat conduction channels in conventional insulating composite coating, significantly improves the heat dissipation power of the battery, reduces the temperature difference between different cells in a large-size energy storage lithium ion battery module, thereby enhancing the temperature uniformity of the outer surface of the battery, ensuring the consistency of the battery during operation, enabling the battery to achieve synchronous aging and not to rapidly decay due to inconsistent operation; meanwhile, the coating has good insulating performance, ensuring the safety of the battery.

Description

Technical Field

[0001] The present disclosure relates to the field of coating technology, and in particular to a thermally conductive insulating coating, a preparation method, and a lithium-ion battery module. Background Art

[0002] Lithium-ion batteries, a new energy source characterized by high voltage, high specific energy, long cycle life, and environmental friendliness, are widely used in portable electronic devices, electric vehicles, and energy storage devices. As lithium-ion batteries capture a growing share of the new energy market, more and more researchers are engaging in lithium-ion battery technology, leading to increasingly stringent requirements for lithium-ion battery performance and safety. As the power and capacity of energy storage lithium-ion battery modules increase, the temperature differences between cells increase, making them susceptible to uneven aging, dendrite formation, internal short circuits, and other issues, ultimately leading to fires and explosions.

[0003] Currently, lithium-ion battery modules are insulated by coating their outer shells with a blue film. However, this film has low thermal conductivity and cannot eliminate the potential risks associated with increased temperature differences between battery cells. Other conventional insulating composite materials also suffer from low thermal conductivity due to discontinuous heat transfer pathways. This also makes it difficult for the battery module to dissipate internal heat quickly, preventing it from dissipating heat through the module's cooling system, potentially leading to battery failure and safety incidents.

[0004] Therefore, in order to address the above problems, it is urgent to improve the thermal conductivity of the insulating shell of the energy storage lithium-ion battery module to reduce the temperature difference between different battery cells in the battery module and improve the safety of the lithium-ion battery. Summary of the Invention

[0005] In order to solve the above technical problems, the present disclosure provides a thermally conductive insulating coating, a preparation method and a lithium-ion battery module. The thermally conductive insulating coating has high thermal conductivity and good stability, which can effectively improve the thermal conductivity and insulation properties of the lithium-ion battery casing, thereby improving the safety of the battery.

[0006] In a first aspect, the present disclosure provides a thermally conductive insulating coating, wherein the material of the thermally conductive insulating coating comprises insulating particles coated with one-dimensional thermally conductive nanofibers;

[0007] The one-dimensional thermally conductive nanofiber comprises a first polymer and a thermally conductive agent dispersed in the first polymer;

[0008] The material of the insulating particles includes a second polymer.

[0009] In this disclosure, insulating particles coated with one-dimensional thermally conductive nanofibers exhibit excellent thermal conductivity and insulation. The one-dimensional thermally conductive nanofibers form a comprehensive heat transfer network on the surface of the insulating particles, which can promote heat dissipation in large-capacity energy storage batteries, reduce temperature unevenness within the battery module, and enhance the operational consistency, electrical performance, and safe and stable operation of ion-based batteries. Furthermore, both the insulating particles and the one-dimensional thermally conductive nanofibers possess excellent insulation properties, ensuring battery safety.

[0010] The following are preferred technical solutions of the present disclosure, but are not intended to limit the technical solutions provided by the present disclosure. Through the following technical solutions, the technical objectives and beneficial effects of the present disclosure can be better achieved and realized.

[0011] As a preferred technical solution of the present disclosure, the thermal conductor includes one or more of aluminum nitride, aluminum oxide, magnesium oxide, silicon carbide or silicon dioxide, such as a combination of aluminum nitride and aluminum oxide, a combination of aluminum oxide and magnesium oxide, a combination of silicon carbide and silicon dioxide, etc.

[0012] Preferably, the particle size of the thermal conductor is 100-1500 nm, such as 100 nm, 200 nm, 500 nm, 800 nm, 1000 nm, 1200 nm or 1500 nm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 200-500 nm.

[0013] The appropriate particle size of the thermal conductor helps to improve the heat transfer effect of the one-dimensional thermal conductive nanofibers.

[0014] Preferably, the first polymer comprises one or more of polysulfone, polyethersulfone resin or polyvinyl pyrrolidone, such as a combination of polysulfone and polyethersulfone resin, a combination of polyethersulfone resin and polyvinyl pyrrolidone, a combination of polysulfone, polyethersulfone resin and polyvinyl pyrrolidone, etc.

[0015] Preferably, the mass ratio of the thermal conductor to the first polymer is (0.8-1.5):10, such as 0.8:10, 1.0:10, 1.2:10 or 1.5:10, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0016] In the present disclosure, an appropriate raw material ratio helps improve the thermal conductivity of the one-dimensional thermally conductive nanofibers. If the amount of thermal conductive agent added is too small, the thermal conductivity effect will be reduced; while if too much is added, it will not be possible to effectively construct a one-dimensional thermally conductive nanofiber network.

[0017] As a preferred technical solution of the present disclosure, the second polymer includes a thermosetting resin.

[0018] Preferably, the particle size of the insulating particles is 100-200 μm, such as 100 μm, 120 μm, 140 μm, 160 μm, 180 μm or 200 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0019] As a preferred technical solution of the present invention, the mass ratio of the one-dimensional thermally conductive nanofibers to the insulating particles is (0.3-0.8):10, for example, 0.3:10, 0.4:10, 0.5:10, 0.6:10, 0.7:10 or 0.8:10, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0020] In the present invention, the appropriate component ratio makes the thermal conductive network more complete and has better thermal conductivity and insulation. If the content of one-dimensional thermal conductive nanofibers is too high, the film forming property will be poor in the later application process.

[0021] In a second aspect, the present disclosure provides a method for preparing the thermally conductive insulating coating according to the first aspect, the preparation method comprising the following steps:

[0022] mixing the thermal conductor and the first polymer with an organic solvent to obtain an electrospinning solution;

[0023] The second polymer is prepared into insulating particles by a melt extrusion granulation method;

[0024] The obtained electrostatic spinning solution adopts electrostatic spinning technology, and the obtained insulating particles adopt electrostatic spraying technology, which are simultaneously sprayed on the surface of the object to be processed, and a thermal conductive insulating coating is obtained after curing.

[0025] The preparation method disclosed herein utilizes a combination of electrospinning and electrostatic spraying. Under the influence of an electrostatic field, one-dimensional thermally conductive fibers are coated on the surface of insulating particles, creating a rapid thermal conductivity network. Simultaneously, through electrostatic action, the insulating particle coating coated with the one-dimensional thermally conductive nanofibers is sprayed onto the surface of the object to be treated, where it solidifies to form a thermally conductive insulating coating. This preparation method is simple and efficient, making it suitable for industrial production and application.

[0026] As a preferred technical solution of the present disclosure, the mass ratio of the thermal conductor, the first polymer and the organic solvent is (0.8-1.5):10:(40-150), for example, 0.8:10:40, 1.0:10:60, 1.0:10:80, 1.2:10:100 or 1.5:10:150, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0027] Preferably, the organic solvent comprises dimethylformamide.

[0028] As a preferred technical solution of the present disclosure, the melt extrusion granulation method includes: sequentially melt-extruding, cooling and pulverizing the second polymer or the second polymer precursor to obtain insulating particles.

[0029] Preferably, the second polymer precursor includes a second polymer matrix and a curing agent.

[0030] The second polymer matrix reacts with the curing agent during the melt extrusion process, thereby curing to form a second polymer.

[0031] The second polymer matrix can be selected such as epoxy resin.

[0032] The curing agent may be selected from one or more of m-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylsulfone, ethylenediamine, diethylenetriamine or polyethylene polyamines, such as a combination of m-phenylenediamine and m-phenylenediamine, a combination of ethylenediamine and diethylenetriamine, and the like.

[0033] Preferably, the mass ratio of the second polymer substrate to the curing agent is 100:(5-10), for example, 100:5, 100:6, 100:7, 100:8, 100:9 or 100:10, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0034] As a preferred technical solution of the present invention, in the electrospinning technology, the voltage is 50-60kV, such as 50kV, 52kV, 54kV, 56kV, 58kV or 60kV, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0035] Preferably, in the electrostatic spraying technology, the voltage is 50-60kV, such as 50kV, 52kV, 54kV, 56kV, 58kV or 60kV, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0036] Preferably, the spraying distance is 200-300 mm, such as 200 mm, 220 mm, 240 mm, 260 mm, 280 mm or 300 mm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0037] Preferably, the curing temperature is 100-120°C, such as 100°C, 105°C, 110°C, 115°C or 120°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0038] In a third aspect, the present disclosure provides a lithium-ion battery module, comprising a battery pack housing and a battery cell encapsulated in the battery pack housing, wherein the surface of the battery pack housing is covered with the thermally conductive insulating coating as described in the first aspect or the thermally conductive insulating coating prepared as described in the second aspect.

[0039] As a preferred technical solution of the present disclosure, the thickness of the thermally conductive insulating coating is 33-100 μm, such as 33 μm, 50 μm, 80 μm, 90 μm or 100 μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0040] The technical solution provided by the embodiments of the present disclosure has the following advantages over the prior art:

[0041] The thermally conductive insulating coating disclosed in the present invention overcomes the low thermal conductivity problem caused by discontinuous heat transfer channels in conventional insulating composite material coatings, significantly improves the heat dissipation power of the battery, reduces the temperature difference between different battery cells in large-size energy storage lithium-ion battery modules, and enhances the temperature uniformity of the battery outer surface, thereby ensuring the consistency of the battery during operation, enabling the battery to age synchronously and not decay rapidly due to inconsistent operation; at the same time, the coating has good insulating properties, ensuring the safety of the battery. DETAILED DESCRIPTION

[0042] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features therein can be combined with each other in the absence of conflict.

[0043] Many specific details are set forth in the following description to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the application examples in the specification are only part of the application examples of the present disclosure, rather than all the application examples.

[0044] In a first aspect, the present disclosure provides a thermally conductive insulating coating, wherein the material of the thermally conductive insulating coating comprises insulating particles coated with one-dimensional thermally conductive nanofibers;

[0045] The one-dimensional thermally conductive nanofiber comprises a first polymer and a thermally conductive agent dispersed in the first polymer;

[0046] The material of the insulating particles includes a second polymer.

[0047] Furthermore, the thermal conductor includes one or more of aluminum nitride, aluminum oxide, magnesium oxide, silicon carbide or silicon dioxide.

[0048] Furthermore, the first polymer includes one or more of polysulfone, polyethersulfone resin or polyvinyl pyrrolidone.

[0049] Furthermore, the mass ratio of the thermal conductor to the first polymer is (0.8-1.5):10.

[0050] Furthermore, the particle size of the thermal conductor is 100-1500 nm, preferably 200-500 nm.

[0051] Furthermore, the insulating particles include thermosetting resin.

[0052] Furthermore, the particle size of the insulating particles is 100-200 μm.

[0053] In a second aspect, the present disclosure provides a method for preparing the thermally conductive insulating coating according to the first aspect, the preparation method comprising the following steps:

[0054] Mixing the thermal conductive agent and the first polymer with an organic solvent in a mass ratio of (0.8-1.5):10:(100-200) to obtain an electrospinning solution;

[0055] The second polymer or the second polymer precursor is sequentially melt-extruded, cooled and crushed to obtain insulating particles with a particle size of 100-200 μm;

[0056] The obtained electrospinning solution is processed by electrospinning technology, and the obtained insulating particles are processed by electrostatic spraying technology, and are simultaneously sprayed on the surface of the object to be treated. The voltage of the electrospinning technology is 50-60kV, the voltage of the electrostatic spraying is 50-60kV, the spraying distance is 200-300mm, and after curing at 100-120°C, a 33-100μm thick thermal conductive insulating coating is formed;

[0057] Wherein, the organic solvent includes dimethylformamide.

[0058] Application Example 1

[0059] This application example provides a lithium-ion battery module, including a battery pack housing and 48 battery cells arranged in series and encapsulated in the battery pack housing; the surface of the battery pack housing is covered with a thermally conductive insulating coating; the battery pack housing is an aluminum shell;

[0060] The preparation method of the thermally conductive insulating coating comprises:

[0061] 5 g of aluminum nitride with a diameter of 500 nm and 50 g of polyethersulfone resin (PES) were mixed with 500 g of dimethylformamide (DMF) to obtain an electrospinning solution;

[0062] 100g of epoxy resin was mixed with 7.5g of m-xylylenediamine, and then melt-extruded through a twin-screw extruder. The extruded flakes were cooled in a crystal drum and then crushed to obtain insulating particles with a particle size of 150μm.

[0063] The obtained electrospinning solution is prepared by electrospinning technology, and the obtained insulating particles are prepared by electrostatic spraying technology, and are simultaneously sprayed on the surface of the aluminum shell. The voltage of the electrospinning technology is 50 kV, the voltage of the electrostatic spraying is 50 kV, and the spraying distance is 250 mm. After curing at 100° C., a 100 μm thick thermally conductive insulating coating is formed.

[0064] In the obtained thermally conductive insulating coating, the mass ratio of the one-dimensional thermally conductive nanofibers to the insulating particles is 0.5:10.

[0065] Application Example 2

[0066] This application example provides a lithium-ion battery module, including a battery pack housing and 48 battery cells arranged in series and encapsulated in the battery pack housing; the surface of the battery pack housing is covered with a thermally conductive insulating coating; the battery pack housing is an aluminum shell;

[0067] The preparation method of the thermally conductive insulating coating comprises:

[0068] 4 g of silicon carbide with a diameter of 200 nm and 50 g of polysulfone were mixed with 550 g of dimethylformamide (DMF) to obtain an electrospinning solution;

[0069] 100g of epoxy resin and 10g of 4,4'-diaminodiphenyl sulfone were mixed and then melt-extruded through a twin-screw extruder. The extruded flakes were cooled by a crystal drum and then crushed to obtain insulating particles with a particle size of 100μm.

[0070] The obtained electrospinning solution is prepared by electrospinning technology, and the obtained insulating particles are prepared by electrostatic spraying technology, and are simultaneously sprayed on the surface of the aluminum shell. The voltage of the electrospinning technology is 50 kV, the voltage of the electrostatic spraying is 50 kV, and the spraying distance is 300 mm. After curing at 110° C., an 80 μm thick thermally conductive insulating coating is formed.

[0071] In the obtained thermally conductive insulating coating, the mass ratio of the one-dimensional thermally conductive nanofibers to the insulating particles is 0.8:10.

[0072] Application Example 3

[0073] This application example provides a lithium-ion battery module, including a battery pack housing and 48 battery cells arranged in series and encapsulated in the battery pack housing; the surface of the battery pack housing is covered with a thermally conductive insulating coating; the battery pack housing is an aluminum shell;

[0074] The preparation method of the thermally conductive insulating coating comprises:

[0075] 6 g of silicon carbide with a diameter of 400 nm and 50 g of polysulfone were mixed with 600 g of dimethylformamide (DMF) to obtain an electrospinning solution;

[0076] 100g of epoxy resin and 5g of ethylenediamine were mixed and then melt-extruded through a twin-screw extruder. The extruded flakes were cooled in a crystal drum and then crushed to obtain insulating particles with a particle size of 200μm.

[0077] The obtained electrospinning solution is prepared by electrospinning technology, and the obtained insulating particles are simultaneously sprayed on the surface of the aluminum shell by electrostatic spraying technology. The voltage of the electrospinning technology is 55kV, the voltage of the electrostatic spraying is 55kV, and the spraying distance is 200mm. After curing at 100°C, a 33μm thick thermal conductive insulating coating is formed.

[0078] In the obtained thermally conductive insulating coating, the mass ratio of the one-dimensional thermally conductive nanofibers to the insulating particles is 0.3:10.

[0079] Comparative Application Example 1

[0080] This comparative application example provides a lithium-ion battery module, which refers to Application Example 1, except that the coating on the surface of the battery pack housing is an insulating coating;

[0081] The preparation method of the insulating coating comprises:

[0082] 100g of epoxy resin was mixed with 7.5g of m-xylylenediamine, and then melt-extruded through a twin-screw extruder. The extruded flakes were cooled in a crystal drum and then crushed to obtain insulating particles with a particle size of 150μm.

[0083] The obtained insulating particles were sprayed on the surface of the aluminum shell using an electrostatic spraying technology, wherein the voltage was 50 kV and the spraying distance was 250 mm, and then cured at 100° C. to form an insulating coating with a thickness of 100 μm.

[0084] The battery modules used in the above application examples and comparative application examples are exactly the same.

[0085] The thermal conductivities of the surface coatings of the battery pack housings in Application Examples 1-3 and Comparative Application Example 1 were measured, and the results are shown in Table 1.

[0086] Table 1

[0087]

[0088]

[0089] As shown in Table 1, the thermally conductive insulating coating disclosed in the present invention has good thermal conductivity, and the thermal conductivity can reach 0.651 W·m -1 ·K -1 above.

[0090] The temperature differences inside the battery modules of the lithium-ion battery modules obtained in Application Examples 1-3 and Comparative Application Example 1 under 1P operating conditions were measured, as shown in Table 2.

[0091] The rated voltage of a single battery cell in the lithium-ion battery module is 3.2V, the capacity is 280Ah, and the charge and discharge power of the lithium-ion battery module is 21.5kW.

[0092] The specific testing method includes: for each battery cell, NTC thermistors are attached to the surface, middle, and bottom of the cell, and the data fed back by the NTC thermistors is recorded at the end of a charge and discharge cycle. The specific temperature is calculated using the temperature-resistance formula, and the highest and lowest temperatures in the obtained temperature data are determined. The temperature difference is the difference between the highest and lowest temperatures.

[0093] Table 2

[0094] Temperature difference / ℃ Application Example 1 4.3 Application Example 2 3.9 Application Example 3 3.9 Comparative Application Example 1 6.5

[0095] Because one-dimensional thermally conductive nanofibers provide excellent thermal conductivity channels, they can effectively improve the uniformity of battery temperature distribution. As shown in Table 2, the aluminum shell coated with the thermally conductive insulating coating described in this disclosure exhibits excellent thermal conductivity. Under 1P operating conditions, the temperature difference between different battery cells in the energy storage lithium-ion battery module can be controlled within 4.3°C. Furthermore, silicon carbide is expensive. Under the same temperature difference conditions, aluminum nitride is economical and cost-effective.

[0096] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0097] The foregoing description is intended only to provide specific embodiments of the present disclosure, intended to enable those skilled in the art to understand and implement the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments described herein, but rather to be construed in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A thermally conductive insulating coating, characterized in that: The material of the thermally conductive insulating coating comprises insulating particles coated with one-dimensional thermally conductive nanofibers; The one-dimensional thermally conductive nanofiber comprises a first polymer and a thermally conductive agent dispersed in the first polymer; The first polymer comprises one or more of polysulfone, polyethersulfone resin or polyvinyl pyrrolidone; The material of the insulating particles includes a second polymer; The second polymer comprises a thermosetting resin; The insulating particles are insulating particles suitable for electrostatic spraying technology.

2. The thermally conductive insulating coating according to claim 1, characterized in that: The thermal conductor includes one or more of aluminum nitride, aluminum oxide, magnesium oxide, silicon carbide or silicon dioxide.

3. The thermally conductive insulating coating according to claim 1, characterized in that: The particle size of the thermal conductor is 100-1500 nm.

4. The thermally conductive insulating coating according to claim 3, characterized in that: The particle size of the thermal conductor is 200-500 nm.

5. The thermally conductive insulating coating according to claim 1, characterized in that: The mass ratio of the thermal conductor to the first polymer is (0.8-1.5):

10.

6. The thermally conductive insulating coating according to claim 1, characterized in that: The thermosetting resin includes epoxy resin.

7. The thermally conductive insulating coating according to claim 1, characterized in that: The particle size of the insulating particles is 100-200 μm.

8. The thermally conductive insulating coating according to claim 1, wherein: The mass ratio of the one-dimensional thermally conductive nanofibers to the insulating particles is (0.3-0.8):

10.

9. A method for preparing a thermally conductive insulating coating according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: mixing the thermal conductor and the first polymer with an organic solvent to obtain an electrospinning solution; The second polymer is prepared into insulating particles by a melt extrusion granulation method; The obtained electrostatic spinning solution adopts electrostatic spinning technology, and the obtained insulating particles adopt electrostatic spraying technology, which are simultaneously sprayed on the surface of the object to be processed, and a thermal conductive insulating coating is obtained after curing.

10. The preparation method according to claim 9, characterized in that The mass ratio of the thermal conductor, the first polymer and the organic solvent is (0.8-1.5):10:(40-150).

11. The preparation method according to claim 9, characterized in that The organic solvent includes dimethylformamide.

12. The preparation method according to claim 9, characterized in that The melt extrusion granulation method comprises: sequentially melt-extruding, cooling and crushing the second polymer or the second polymer precursor to obtain insulating particles.

13. The preparation method according to claim 9, characterized in that In the electrospinning technology, the voltage is 50-60 kV.

14. The preparation method according to claim 9, characterized in that In the electrostatic spraying technology, the voltage is 50-60 kV.

15. The preparation method according to claim 9, characterized in that The spraying distance is 200-300 mm.

16. The preparation method according to claim 9, characterized in that The curing temperature is 100-120°C.

17. A lithium-ion battery module comprising a battery pack housing and a battery cell encapsulated in the battery pack housing, characterized in that: The surface of the battery pack shell is covered with the thermally conductive insulating coating according to any one of claims 1 to 8 or the thermally conductive insulating coating prepared by the preparation method according to any one of claims 9 to 16.

18. The lithium-ion battery module according to claim 17, wherein: The thickness of the thermally conductive insulating coating is 33-100 μm.

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