CN115403857A

CN115403857A - Heat-conducting insulating film and battery pack comprising same

Info

Publication number: CN115403857A
Application number: CN202210404208.4A
Authority: CN
Inventors: 孟凡良
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 2021-05-27
Filing date: 2022-04-18
Publication date: 2022-11-29

Abstract

The application discloses heat conduction insulating film includes: thermoplastic resin, the weight of the thermoplastic resin accounts for 15-50% of the weight of the heat-conducting insulating film; and heat-conducting filler, the weight of the heat-conducting filler accounts for 40-70% of that of the heat-conducting insulating film; wherein the thermally conductive filler includes: carbon-based heat conductive filler, metal oxide or hydroxide heat conductive filler and ceramic heat conductive filler. The heat-conducting insulating film is used for electronic products or equipment, can provide good heat dissipation capacity for the electronic products and the equipment, and can meet the requirement of the electronic products and the equipment on insulativity. Meanwhile, the heat-conducting insulating film has the characteristics of good flame retardance, good mechanical property and the like so as to meet the requirements of the use environment.

Description

Heat-conducting insulating film and battery pack comprising same

Technical Field

The present application relates to the field of films, and more particularly, to a thermally conductive insulating film and a battery pack including the same.

Background

Electronic products or devices generate a large amount of heat during use. In order to ensure the working stability and prolong the service life of electronic products and equipment, the electronic products or equipment are expected to have good heat dissipation capability. Thermally conductive materials are used in electronic products and devices to provide good heat dissipation capabilities for the electronic products and devices. Since the heat conductive material is used for electronic products and devices, it is desirable that the heat conductive material has an insulating property at the same time.

Disclosure of Invention

The purpose of the application is to provide a heat-conducting insulating film which is used for electronic products or equipment, can provide good heat dissipation capacity for the electronic products or equipment, and can meet the requirement of the electronic products or equipment on insulating property. Meanwhile, the heat-conducting insulating film has the characteristics of good flame retardance, good mechanical property and the like so as to meet the requirements of the use environment.

The present application provides in a first aspect a thermally conductive insulating film comprising: thermoplastic resin, the weight of the thermoplastic resin accounts for 15-50% of the weight of the heat-conducting insulating film; and heat-conducting filler, the weight of said heat-conducting filler accounts for 40-70% of the weight of said heat-conducting insulating film; wherein the thermally conductive filler includes: carbon-based heat conductive filler, metal oxide or hydroxide heat conductive filler and ceramic heat conductive filler.

According to the first aspect, the carbon-based thermally conductive filler accounts for 2 to 15% by weight of the thermally conductive insulating film.

According to the first aspect, the carbon-based thermally conductive filler accounts for 10 to 15% by weight of the thermally conductive insulating film.

According to the first aspect, the carbon-based heat conductive filler is one or more of graphite, carbon nanotubes, and graphene.

According to the first aspect described above, the graphite is at least one of flake graphite and expanded graphite.

According to the first aspect, the carbon-based thermally conductive filler is flake graphite.

According to the first aspect, the graphite has a particle size of 10nm to 200 μm, the carbon nanotube has a diameter of 2 to 200nm, and the graphene has a diameter-thickness ratio of 500 to 8000.

According to the first aspect, the metal oxide or hydroxide heat conductive filler accounts for 5 to 55% of the weight of the heat conductive insulating film.

According to the first aspect, the metal oxide or hydroxide heat conductive filler accounts for 20 to 50% of the weight of the heat conductive insulating film.

According to the first aspect, the metal oxide or hydroxide thermally conductive filler comprises one or more of magnesium oxide, zinc oxide, aluminum oxide, magnesium hydroxide, and aluminum hydroxide.

According to the first aspect described above, the metal oxide or hydroxide thermally conductive filler is in the form of particles.

According to the first aspect, the ceramic-based thermally conductive filler accounts for 2 to 50% by weight of the thermally conductive insulating film.

According to the first aspect, the ceramic-based thermally conductive filler accounts for 5 to 40% by weight of the thermally conductive insulating film.

According to the first aspect described above, the ceramic-based thermally conductive filler includes one or more of boron nitride, silicon carbide, and aluminum nitride.

According to the first aspect, the ceramic-based thermally conductive filler is in a sheet or a spherical shape.

According to the first aspect described above, the thermoplastic resin is a polypropylene resin.

According to the first aspect, the heat conductive insulating film further includes a flame retardant, and the flame retardant accounts for 10 to 45% of the weight of the heat conductive insulating film.

According to the first aspect, the flame retardant is at least one of a phosphorus-nitrogen flame retardant, a phosphorus-nitrogen-silicon flame retardant and a bromine flame retardant.

The present application provides in a second aspect a battery pack comprising: a battery pack housing including a bottom wall and a side wall; a battery pack module disposed in the battery pack case; and a thermally conductive insulating film disposed between the battery module and at least one of the bottom wall and the side wall of the battery pack case; wherein the thermally conductive insulating film is as described in the first aspect.

Drawings

Fig. 1 is a schematic structural view of one embodiment of a battery pack including a thermally conductive insulating film of the present application.

Detailed Description

Various embodiments of the present application will now be described with reference to the accompanying drawings, which form a part hereof. It should be understood that although directional terms, such as "front," "rear," "upper," "lower," "left," "right," "top," "bottom," "inner," "outer," and the like may be used herein to describe various example structural portions and elements of the application, these terms are used herein for convenience of description only and are intended to be based on the example orientations shown in the figures. Because the embodiments disclosed herein can be arranged in a variety of orientations, these directional terms are used for purposes of illustration only and are not to be construed as limiting.

In this application, all equipment and materials are commercially available or commonly used in the industry, and the methods in the following examples, unless otherwise specified, are conventional in the art.

The thermally conductive insulating film of the present application includes a thermoplastic resin and a thermally conductive filler. The thermoplastic resin accounts for 15-50% of the total weight of the heat-conducting insulating film, and the heat-conducting filler accounts for 40-70% of the total weight of the heat-conducting insulating film. In some embodiments, the thermoplastic resin comprises 17.5 to 32.5% by weight of the total weight of the thermally conductive insulating film. In some embodiments, the thermally conductive filler comprises 40 to 65% by weight of the total weight of the thermally conductive insulating film. Wherein, the heat conduction filler includes: carbon series heat conduction filler, metal oxide or hydroxide heat conduction filler and ceramic heat conduction filler.

The thermoplastic resin is a polypropylene resin. Wherein the polypropylene resin is homopolymerized or copolymerized polypropylene, and the melt index of the polypropylene resin is 0.1-100 g/10min (230 ℃,2.16 kg). In other embodiments, other thermoplastic resins, such as polyethylene, polyvinyl chloride, polycarbonate, and the like, may also be used.

The carbon-based heat-conducting filler is one or more of graphite, carbon nano tubes and graphene. Wherein the graphite may be at least one of flake graphite and expanded graphite. The particle size of the graphite is 10 nm-200 mu m, the diameter of the carbon nano tube is 2-200 nm, and the diameter-thickness ratio of the graphene is 500-8000. In some embodiments, the carbon-based thermally conductive filler is flake graphite. The addition of the carbon-based heat-conducting filler enables the heat-conducting insulating film to have excellent heat-conducting capacity. However, since the carbon-based heat conductive filler has electrical conductivity, it is generally not conceivable to use the carbon-based heat conductive filler in products requiring insulation properties. Surprisingly, the inventors of the present application found that controlling the amount of the carbon-based thermally conductive filler to 2 to 15% by weight based on the total weight of the thermally conductive and insulating film makes it possible to provide a thermally conductive and insulating film having excellent thermal conductivity while maintaining good insulating properties. In some embodiments, the carbon-based thermally conductive filler may account for 10 to 15% of the total weight of the thermally conductive insulating film.

The metal oxide or hydroxide heat-conducting filler accounts for 5-55% of the total weight of the heat-conducting insulating film. In some embodiments, the metal oxide or hydroxide thermally conductive filler comprises 20 to 50% of the total weight of the thermally conductive insulating film. The metal oxide or hydroxide heat conducting filler comprises one or more of magnesium oxide, zinc oxide, aluminum oxide, magnesium hydroxide and aluminum hydroxide. The metal oxide or hydroxide heat-conducting filler is granular.

The ceramic heat-conducting filler accounts for 2-50% of the total weight of the heat-conducting insulating film. In some embodiments, the ceramic-based thermally conductive filler accounts for 5 to 40% of the total weight of the thermally conductive insulating film. The ceramic heat conducting filler comprises one or more of boron nitride, silicon carbide and aluminum nitride. The ceramic heat-conducting filler is flaky or spherical. The ceramic-based heat conductive filler has excellent heat conductive properties, and thus provides excellent heat conductive properties to the heat conductive insulating film of the present application.

In some embodiments, the thermally conductive insulating film further comprises a flame retardant in an amount of 10 to 45% by weight based on the total weight of the thermally conductive insulating film, according to the requirement of flame retardancy. In some embodiments, the flame retardant comprises 10 to 26% of the total weight of the thermally conductive insulating film. In some embodiments, the flame retardant is at least one of a phosphorus nitrogen based flame retardant, a phosphorus nitrogen silicon based flame retardant, and a bromine based flame retardant. In some embodiments, the flame retardant further comprises an auxiliary flame retardant, which is one or more of antimony trioxide, borate salts, and the like. The surface resistivity of the heat-conducting insulating film can reach 10 ¹² Ω.m。

In some embodiments, the thermally conductive insulating film further comprises one or more of a toughening agent in an amount of 0 to 10 wt%, a compatibilizer in an amount of 0 to 5 wt%, a lubricant in an amount of 0.1 to 1 wt%, an antioxidant in an amount of 0 to 1.5 wt%, and a toner in an amount of 0 to 2 wt%, based on the total weight of the thermally conductive insulating film. In some embodiments, the compatibilizer comprises 0 to 3% of the total weight of the thermally conductive insulating film. In some embodiments, the lubricant comprises 0.2 to 0.5% by weight of the total weight of the thermally conductive and insulating film. The toughening agent comprises one or more of propylene-based elastomer, styrene elastomer (such as hydrogenated poly (styrene-b-isoprene), hydrogenated poly (styrene-b-butadiene-b-styrene), hydrogenated poly (styrene-b-isoprene-b-styrene) and hydrogenated poly (styrene-b-isoprene/butadiene-b-styrene)), copolymerized polyolefin elastomer (such as ethylene-octene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, etc.), and polyethylene. The compatilizer comprises one or more of alkyl silane coupling agent, maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene and maleic anhydride grafted polyolefin elastomer (POE). The lubricant comprises one or more of silicon lubricant, amide lubricant, stearic acid lubricant and polytetrafluoroethylene. The antioxidant comprises one or more of hindered phenol antioxidant, phosphite antioxidant and sulfur-containing antioxidant. As described above, the carbon-based heat conductive filler, the particulate metal oxide or hydroxide heat conductive filler, and the sheet-like ceramic heat conductive filler used in the heat conductive insulating film of the present application have excellent heat conductive properties, and thus the heat conductive insulating film of the present application has excellent heat conductive properties.

Further, through the synergistic effect of three kinds of heat conduction fillers that use among this application heat conduction insulation film, this application heat conduction insulation film's heat conductivility further obtains improving. Specifically, the inventors of the present application found that the sheet-shaped ceramic-based heat conductive filler can connect the carbon-based heat conductive filler and the particulate metal oxide or hydroxide heat conductive filler to form a heat conductive channel in the heat conductive insulating film, so that the heat conductive performance of the heat conductive insulating film is further improved. The spherical ceramic-based heat conductive filler is formed by controlling the crystal growth direction of the flaky ceramic-based heat conductive filler. Since the spherical ceramic heat conductive material is formed of the flaky ceramic heat conductive filler, the spherical ceramic heat conductive filler has the above-mentioned advantages of the flaky ceramic heat conductive filler. Moreover, the spherical ceramic heat-conducting filler has isotropy, and the spherical ceramic heat-conducting filler is also beneficial to heat conduction in the direction of penetrating through the flaky plane, so that the heat-conducting property of the heat-conducting insulating film is further improved.

In addition, the heat-conducting filler is selected, so that the heat-conducting insulating film can be ensured to have excellent heat-conducting performance under the condition of reducing the using amount of the heat-conducting filler. The heat conductivity coefficient of the heat-conducting insulating film can reach 1-1.46W/m.K.

In addition, because the heat conduction insulating film of this application has reduced the quantity of heat conduction filler when having good heat conductivity, the heat conduction insulating film of this application has better mechanical properties. The inventors of the present application have found that in order to provide a film prepared using a thermoplastic resin with good thermal conductive properties, a large amount of a thermally conductive filler needs to be used. The larger the amount of the heat-conducting filler, the smaller the amount of the thermoplastic resin, and the poorer the mechanical properties of the heat-conducting insulating film. The heat conduction insulating film of this application makes can use a smaller amount of heat conduction filler through the selection to the heat conduction filler to thermoplastic resin accounts for in the heat conduction insulating film of this application and improves, therefore the heat conduction insulating film of this application has better mechanical properties, especially has good tensile elongation and elongation at break. The better mechanical properties of the thermally conductive insulating film of the present application make the thermally conductive insulating film of the present application less susceptible to breakage when packaged, shipped (e.g., rolled for storage and shipping) and finally formed (e.g., folded, cut for use in electronic products and equipment) by electronic product and equipment manufacturers, etc. For example, the thermally conductive insulating film of the present application has excellent toughness so that the thermally conductive insulating film of the present application can be folded five times during the molding process without being damaged.

Because the heat conduction insulating film of this application has good heat conductivility, when using the heat conduction insulating film of this application to electronic product or equipment, need not again to the heat conduction glue of heat conduction insulating film coating of this application, and can be directly with in its pressfitting electronic product or the equipment. Therefore, the heat conduction insulating film is convenient to use, saves cost, and is favorable for reducing the weight and the size of electronic products and equipment.

In addition, the heat conductive insulating film of the present application can be produced by a conventional cast film process, and thus the production process is simple.

The effects of the heat conductive insulating film of the present application are explained below by a heat conductive insulating film sample of a specific example and a film sample of a comparative example. Table 1 shows the contents of the respective components in the film samples of the examples and comparative examples of the present application, and table 2 shows the performance data of the film samples of the examples and comparative examples.

Film samples of the examples and comparative examples in table 1 were prepared as follows: the raw materials of the components in table 1 were weighed according to the component contents in table 1, and added into a high-speed mixer to mix for 3 minutes, with the rotating speed of the high-speed mixer being 2000 rpm. Adding the mixed raw materials into a double-screw extruder for extrusion, cooling and granulation, wherein the temperature of the double-screw extruder is 180-230 ℃, and the rotating speed of a screw is 300 r/min. The obtained granules are dried, extruded into a film, cut into standard test pieces and subjected to performance test. The samples required for the thermal conductivity test were compression molded at 220 ℃ using a press vulcanizer.

TABLE 1 content of each component in films of examples and comparative examples

	Comparative example	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6	Example 7	Example 8
										Name of raw material	Percent by weight%	Percent by weight%	Percent%	Percent by weight%	Percent by weight%	Percent%	Percent by weight%	Percent by weight%	Percent by weight%
PP resin	18.3	24.5	32.5	17.5	27.5	27.5	26.5	19.7	26.7
										Toughening agent	0	1.8	1.6	1.5	1.6	1.6	0	10	1.3
Compatilizer	0	1.8	1.5	1	1.5	1.5	1	3	0
										Flame retardant	21.0	26.2	24.2	15	24.2	24.2	10	16	20
Graphite	0	4.6	4.6	4.6	2	15	5	10	5
										Magnesium oxide	60	16.5	25	50	27.6	14.6	0	20	0
Alumina oxide	0	0	0	0	0	0	55	-	5
										Boron nitride	0	23.9	10	10	15	15	2	21	40
Antioxidant agent	0.2	0.2	0.2	0.2	0.2	0.2	0.2	-	1.5
										Lubricant agent	0.5	0.5	0.4	0.2	0.4	0.4	0.3	0.3	0.3
Total	100.0	100.0	100	100	100	100	100.0	100.0	100

In Table 1, the PP resin is a co-polypropylene resin having a melting temperature of about 160 ℃; the toughening agent is an ethylene-octene copolymer; the compatilizer is an alkyl silane coupling agent; the flame retardant is a phenylate brominated flame retardant; the graphite is flake graphite with the grain diameter of 1-50 mu m, and is subjected to surface alkylation treatment; the alumina is spherical alumina with the grain diameter of 5-20 mu m, and is subjected to surface alkylation treatment; the magnesium oxide is spherical magnesium oxide with the particle size of 5-30 mu m; the boron nitride is flaky boron nitride; the antioxidant is hindered phenol stabilizer; the lubricant is stearate.

TABLE 2 Performance data for films of examples and comparative examples

As can be seen from the above tables 1 and 2, the film of the comparative example has the addition amount of the heat conductive filler of 60%, the addition amount of the PP resin of 18.3%, and the heat conductive material includes only one kind of magnesium oxide, and the film of the comparative example can achieve a heat conductivity of 0.94W/m.k, but has a tensile yield strength of only 16.3MPa and an elongation at break of only 9.2%. The film illustrating the comparative example, while satisfactory in thermal conductivity, is inferior in mechanical properties.

In contrast, in the respective embodiments of the present application, by setting the kind of the heat conductive filler to be made of three types of heat conductive fillers, the heat conductivity of the film can be maintained almost the same as or higher than that of the comparative example. As the content of the thermally conductive filler increases, the thermal conductivity of the film increases accordingly. In examples 1 to 2, 4 to 5 and 7 to 8, the heat conductive filler was used in an amount smaller than that of the comparative example, while obtaining a heat conductive effect equivalent to or better than that of the comparative example. In the case where a large amount of the thermally conductive filler was used in examples 3 and 6 (64.6% in example 3 and 62% in example 6), the thermal conductivity of the film was higher.

Meanwhile, since the addition amount of the heat conductive filler in the present embodiment can be smaller than that in the comparative example, the film of the present embodiment can use PP resin with a higher addition amount. As shown in Table 2, the mechanical properties of the film of this example are better with increasing PP resin addition, such as tensile yield strength and elongation at break are significantly better than those of the comparative example, indicating that the toughness of the film of this example is better. Even in the case of example 3 in which the amount of the PP resin added was smaller than that of the comparative example, the mechanical properties of the film were slightly stronger than those of the comparative example by adding the toughening agent and the compatibilizer.

In addition, as shown in table 2, the thermally conductive insulating film of the present example can achieve the same insulating properties as the comparative example, despite the use of flake graphite as a thermally conductive additive. In addition, the flame retardant property and the voltage breakdown resistance of the heat-conducting insulating film are better than those of a comparative example. As shown in table 2, the heat conductive insulating film of the present application provides better performance than the film of the comparative example as a whole, and the weight of the film per unit volume is lighter, which is more suitable for the development trend of small size and light weight of the electronic products and devices.

The thermally conductive insulating film of the present application can be used for various electronic products or devices to help heat dissipation of the electronic products and devices. Such electronic products or devices may be battery packs, notebook computers, power adapters for computers, and the like.

Fig. 1 is a schematic structural view of an embodiment of a battery pack including a thermal conductive insulation film of the present application, in which only a partially exploded structure of the battery pack is shown in order to more clearly show the position of the thermal conductive insulation film. As shown in fig. 1, the battery pack 100 includes a battery pack module 120 composed of a plurality of battery cells 101 and a battery pack case 110. The battery pack case 110 includes top and bottom walls (not shown) and 105 disposed opposite to each other, and four side walls 106 surrounding and connected between the top and bottom walls 105. Battery module 120 is housed within housing cavity 108 bounded by top, bottom and

side walls

105, 106. Each battery cell 101 has a respective connection terminal 103. The respective connection terminals 103 of the battery cells 101 are electrically connected together according to a predetermined circuit, and then are externally supplied with power and/or charged through a general connection terminal (not shown) provided on the pack case 110.

The thermally conductive insulating film 112 is disposed between the battery module 120 and the bottom wall 105 of the battery pack case 110. Through the thermally conductive insulating film 112, heat generated by the battery module 120 during operation can be dissipated to the external environment through the bottom wall 105 of the battery housing 110 in a timely manner without being collected in the housing receptacle 108 of the battery housing 110.

It should be noted that, in the embodiment shown in fig. 1, although the thermally conductive insulating film 112 is disposed only between the battery module 120 and the bottom wall 105 of the battery pack case 110, it may be disposed between the battery module 120 and the side wall 106 of the battery pack case 110 according to the actual space design and heat dissipation requirements.

Finally, the thermally conductive insulating film of the present application has many advantageous technical effects, and at least some of the technical effects of the thermally conductive insulating film of the present application are listed as follows:

1. the heat conducting performance is excellent, and the heat conducting or heat dissipating requirements of electronic products and equipment can be met.

2. The excellent mechanical property ensures that the product is not easy to damage in the processes of transportation, packaging and processing and forming of electronic products and equipment manufacturers.

3. Excellent insulating property to meet the requirement of electronic products and equipment on insulating property.

4. The production process is simple.

5. The electronic device is convenient to use, saves cost, and is beneficial to reducing the weight and the size of electronic products and equipment.

6. The film per unit volume is lighter in weight, and is more suitable for the development trend of small size and light weight of the current electronic products and equipment.

Although the present application will be described with reference to the particular embodiments illustrated in the drawings, it should be understood that many variations of the thermally conductive and insulating film of the present application are possible without departing from the spirit and scope and background of the teachings of the present application. Those of ordinary skill in the art will also appreciate that there are different ways to alter the structure of the embodiments disclosed herein, all within the spirit and scope of the present application and claims.

Claims

1. A thermally conductive insulating film characterized by comprising:

thermoplastic resin, the weight of the thermoplastic resin accounts for 15-50% of the weight of the heat-conducting insulating film; and

the heat-conducting filler accounts for 40-70% of the weight of the heat-conducting insulating film;

wherein the thermally conductive filler includes: carbon-based heat conductive filler, metal oxide or hydroxide heat conductive filler and ceramic heat conductive filler.

2. The thermally conductive insulating film according to claim 1, wherein:

the carbon-based heat-conducting filler accounts for 2-15% of the weight of the heat-conducting insulating film.

3. The thermally conductive insulating film according to claim 2, wherein:

the carbon-based heat-conducting filler accounts for 10-15% of the weight of the heat-conducting insulating film.

4. The thermally conductive insulating film according to claim 1, wherein:

the carbon-series heat-conducting filler is one or more of graphite, carbon nano tubes and graphene.

5. The thermally conductive insulating film according to claim 4, wherein:

the graphite is at least one of flake graphite and expanded graphite.

6. The thermally conductive insulating film according to claim 5, wherein:

the carbon-based heat-conducting filler is flake graphite.

7. The thermally conductive insulating film according to claim 4, wherein:

the particle size of the graphite is 10 nm-200 mu m, the diameter of the carbon nano tube is 2-200 nm, and the diameter-thickness ratio of the graphene is 500-8000.

8. The thermally conductive insulating film according to claim 1, wherein:

the metal oxide or hydroxide heat-conducting filler accounts for 5-55% of the weight of the heat-conducting insulating film.

9. The thermally conductive insulating film according to claim 8, wherein:

the metal oxide or hydroxide heat-conducting filler accounts for 20-50% of the weight of the heat-conducting insulating film.

10. The thermally conductive insulating film according to claim 1, wherein:

the metal oxide or hydroxide heat conducting filler comprises one or more of magnesium oxide, zinc oxide, aluminum oxide, magnesium hydroxide and aluminum hydroxide.

11. The thermally conductive insulating film according to claim 10, wherein:

the metal oxide or hydroxide heat-conducting filler is granular.

12. The thermally conductive insulating film according to claim 1, wherein:

the ceramic heat-conducting filler accounts for 2-50% of the weight of the heat-conducting insulating film.

13. The thermally conductive insulating film according to claim 12, wherein:

the ceramic heat-conducting filler accounts for 5-40% of the weight of the heat-conducting insulating film.

14. The thermally conductive insulating film according to claim 1, wherein:

the ceramic heat conducting filler comprises one or more of boron nitride, silicon carbide and aluminum nitride.

15. The thermally conductive insulating film according to claim 14, wherein:

the ceramic heat-conducting filler is flaky or spherical.

16. The thermally conductive insulating film according to claim 1, wherein:

the thermoplastic resin is polypropylene resin.

17. The thermally conductive insulating film according to claim 1, wherein:

the heat-conducting insulating film also comprises a flame retardant, wherein the flame retardant accounts for 10-45% of the weight of the heat-conducting insulating film.

18. The thermally conductive insulating film according to claim 17, wherein:

the flame retardant is at least one of a phosphorus-nitrogen flame retardant, a phosphorus-nitrogen-silicon flame retardant and a bromine flame retardant.

19. A battery pack, comprising:

a battery pack housing including a bottom wall and a side wall;

a battery pack module disposed in the battery pack case; and

a thermally conductive insulating film disposed between the battery module and at least one of the bottom wall and the side wall of the battery housing;

wherein the thermally conductive insulating film is as set forth in any one of claims 1 to 18.