Inorganic Materials to Improve Thermal Insulation for Under-Lid Applications for Battery-Safe Vehicle Electrification

Abstract

In one aspect of the present disclosure, a thermal runaway protective film for a lithium ion battery is provided, the thermal runaway protective film comprising at least one protective layer comprising at least one silicone, and at least one silicate compound in an amount of at least 40 wt % based on a total weight of the at least one protective layer.

Description

[Technical field]

[0001] The present disclosure relates to a thermal protection film for lithium ion batteries. The present disclosure further provides a method for preparing the thermal runaway protection film. Furthermore, the present disclosure relates to the use of the thermal runaway protection film for preventing or mitigating thermal runaway events in lithium ion batteries. Finally, the present disclosure provides a lithium ion battery module and a lithium ion battery comprising the thermal protection film described herein. [Background technology]

[0002] Batteries based on lithium-ion technology are currently the preferred solution for automotive e-mobility. Typically, several lithium-ion cells are stacked in a row to form a battery module. In a typical automotive application, the battery consists of several modules within a housing.

[0003] Such lithium-ion batteries have an operating window from room temperature to about 40°C. Above temperatures of about 80-100°C, there is a risk of uncontrolled electrolyte decomposition followed by additional heat and pressure rise inside the cell. Finally, the separator in the cell melts and the resulting internal shortcut leads to an excessive temperature rise, called thermal runaway. This also leads to a sudden and significant increase in gas pressure inside the cell, which can destroy or explode the cell, leading to hot gases escaping the cell at temperatures above 1200°C, which can further ignite outside the cell and lead to damage to the surrounding cells, with the same result. Of course, this scenario is of great concern in modern electric vehicles, especially in automotive structures. Recent regulations and laws already take this into account and require a minimum time that passengers can safely leave the vehicle after the occurrence of a thermal runaway event.

[0004] There is therefore a need in the art for materials that can stop or at least significantly slow down such thermal runaway, i.e., materials that exhibit particular resistance to heat and blast, mechanical strength, and / or are readily accessible, easy to manufacture, transport and apply. It is also desirable for the materials to be easily formed into three-dimensional shapes, and also to provide some type of thermal and electrical insulation. Summary of the Invention

[0005] The present disclosure provides a thermal runaway protection film for a lithium ion battery, comprising: A thermal runaway protection film is provided that includes at least one protective layer including at least one silicone and at least one silicate compound in an amount of at least 40 wt % based on the total weight of the at least one protective layer.

[0006] The present disclosure further provides a battery casing comprising the thermal runaway protection film composite structure described herein.

[0007] The present disclosure further provides a method for producing a thermal runaway protection film, comprising the steps of: (i) incorporating at least one silicate compound into a silicone; (ii) forming at least one protective layer from the silicone composition obtained in step (i); (iii) optionally drying or curing the at least one protective layer obtained in step (ii), thereby obtaining a thermal runaway protection film; The at least one silicate compound is contained in the at least one protective layer in an amount of at least 40% by weight, based on the total weight of the at least one protective layer.

[0008] Finally, the present disclosure provides for the use of a thermal runaway protective film to prevent or mitigate thermal runaway events in lithium ion batteries. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Before describing any embodiment of the present disclosure in detail, it should be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description. The invention is capable of other embodiments and of being practiced or carried out in various ways. As used herein, the terms "a," "an," and "the" are used interchangeably to mean one or more, and "and / or" is used to indicate that one or both of the stated instances may occur, e.g., A and / or B includes (A and B) as well as (A or B). Further herein, recitations of ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.). Further herein, recitations of "at least 1" include all numbers greater than or equal to 1 (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.). It is also to be understood that the phraseology and terminology used herein is for purposes of description and should not be considered limiting. Unlike the use of "consisting," which is intended to be limiting, the use of "including," "containing," "comprising," or "having," and variations thereof, is intended to be open-ended and to encompass those subsequently listed items as well as additional items. Furthermore, it is understood that the term "comprise" as used herein may also encompass the term "consists of" in the sense of "consists only of," but is generally used according to its meaning as generally used in the art. Thus, limiting "comprise" to "consists" or limiting "comprising" to "consisting of" is fully encompassed by this disclosure.

[0010] Amounts of components of a composition may be indicated by weight % (or "%wt" or "wt-%") unless otherwise specified. All component amounts equal 100 weight % unless otherwise specified. When component amounts are specified by mole %, all component amounts equal 100 mole % unless otherwise specified.

[0011] In the context of this disclosure, the terms "room temperature" and "ambient temperature" are used interchangeably and refer to a temperature of 23° C. (±2° C.) at ambient pressure conditions of about 101 kPa.

[0012] Unless expressly stated otherwise, all embodiments and optional features of the present disclosure can be freely combined.

[0013] The present disclosure is a thermal runaway protective film for a lithium ion battery, comprising at least one protective layer comprising at least one silicone, and at least one silicate compound in an amount of at least 40 weight percent based on the total weight of the at least one protective layer.

[0014] The thermal runaway protective film according to the present disclosure may exhibit at least one or even a combination of desirable properties such as good handling properties, cheap and easy manufacture, non-toxicity, ability to bend and mold, and ability to withstand high temperatures, especially when high temperatures and / or particle and / or gas flow are applied only locally or in small areas of the battery composite structure. In particular, the fact that the protective film described herein is in the form of a silicone film provides the advantage that the protective film is flexible, easy to handle, easy to transport, easy to apply even by high-speed robotic equipment, and can be molded into other shapes desired to manufacture battery modules or batteries. Furthermore, silicone films are not usually resistant to high temperatures and / or blast waves encountered during a thermal runaway event, especially in modern lithium-ion batteries used in the automotive industry. However, it has become possible to provide a protective film that actually withstands this difficult effect, at least for a certain period of time, by using silicate compounds in the amounts described herein.

[0015] Thus, protective films according to the present disclosure are well suited to mitigating or even preventing the high temperature and rapid explosions that typically occur during a thermal runaway event in modern batteries, such as lithium ion batteries used in modern vehicles.

[0016] Protective films according to the present disclosure can be provided in any common form and shape known and recognized in the art. Thus, films can be provided in rolls, sheets, or die cut.

[0017] Generally, the protective film described herein comprises at least one protective layer comprising at least one silicone and at least one silicate compound in an amount of at least 40% by weight based on the total weight of the at least one protective layer. Thus, protective films consisting of one protective layer are encompassed by the present disclosure, and also two, three, four or more layers are disclosed herein. At least one silicate compound is contained in at least one protective layer in an amount of at least 40% by weight based on the total weight of the at least one protective layer. This amount is preferably higher, i.e., at least one protective layer comprises at least 45% by weight, preferably at least 50% by weight, more preferably at least 60% by weight of at least one silicate compound based on the total weight of the protective layer of the at least one layer. The high loading of silicate compound into the silicone matrix of the at least one protective layer provides improved mechanical, chemical and temperature resistance, while the overall properties of the silicone film are preserved. In particular, the film can still be bent, rolled and generally flexible. This is particularly advantageous for the manufacture, storage, and application of the film, and is desirable for many applications or protective films as described herein. Preferably, the at least one silicate compound of the protective film according to the present disclosure is contained in the at least one protective layer in an amount of up to 85 wt%, preferably up to 80 wt%, more preferably up to 77.5 wt%, based on the total weight of the at least one protective layer.

[0018] The at least one silicate compound is not particularly limited, as long as it is compatible with at least one silicone and provides the desired effect of improved heat resistance and mechanical resistance of the protective layer.The best results have been found in kaolin, metakaolin, mullite, wollastonite, and any combination and mixture thereof.Among these compounds, mullite provides the best temperature resistance.Therefore, it is preferred that the at least one silicate compound is selected from kaolin, metakaolin, mullite, wollastonite, and any combination and mixture thereof, preferably metakaolin, mullite, and wollastonite, and any combination and mixture thereof, more preferably mullite and / or wollastonite, and even more preferably mullite.

[0019] The at least one silicone used herein is not particularly limited, so long as it can produce a stable film.The silicones for this purpose are well known in the art and are readily commercially available, even in industrial quantities.The silicones may also be selected with respect to the desired properties and intended use of the protective film.Preferably, the at least one silicone used herein is selected from silicone rubber.For example, the silicones / silicone rubbers for use herein are commercially available from Wacker Chemie AG under the trade name SilGel, for example Wacker SilGel 612 A / B.

[0020] The at least one protective layer may further comprise an inorganic filler, preferably selected from silicon oxide, metal hydroxide, preferably aluminum hydroxide and / or magnesium hydroxide, aluminum oxide, and any combinations and mixtures thereof.

[0021] Furthermore, the addition of a woven or nonwoven layer may also be advantageous with respect to the manufacture, stability and / or handling of the protective film described herein.Thus, it is preferred that the protective film according to the present invention further comprises at least one woven or nonwoven layer.In this regard, it is preferred that the at least one woven or nonwoven layer comprises organic or inorganic fibers, preferably nonwoven fibers such as fleece or cloth.It is also preferred that the organic fibers are selected from polymeric fibers and the inorganic fibers are glass fibers.

[0022] Although it is already advantageous for the protective film according to the present disclosure to be flexible, bendable and conformable to shape, it is further advantageous for some applications for the protective film to remain fixed in the molded shape. For example, it is advantageous if the protective film wrapped around the cell, module or battery is fixed in a more rigid state after the cell, module or battery is manufactured. It has been found that this can be achieved by adding or incorporating a thermoplastic grid into the protective film described herein. It is therefore preferred that the protective film according to the present disclosure further comprises at least one polymer grid, preferably a thermoplastic grid. The use of a thermoplastic grid has the advantage that the protective film is fixed in a preformed shape by simple heating and subsequent cooling. The at least one polymer grid may be incorporated into or attached onto the at least one protective layer. In particular, the latter is advantageous from a manufacturing point of view, since the thermoplastic grid can simply be laminated onto a premanufactured film as an option in a large-scale manufacturing process. It is therefore preferred that the polymer grid, preferably a thermoplastic grid, is laminated onto the at least one protective layer. In this regard, the polymer grid is preferably a thermoplastic grid, a thermoplastic mesh or a thermoplastic scrim. Preferably, the thermoplastic grid comprises at least one thermoplastic material selected from acrylonitrile-butadiene-styrene (ABS), polyamide (PA), polylactate (PLA), polymethylmethacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (polyethelenetherephthalate, PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyetheretherketone (PEEK), polyvinyl chloride (PVC), and any combinations and mixtures thereof, preferably polypropylene and polyamide. Thermoplastic grids and the like are readily commercially available and can be selected by those skilled in the art according to the intended use of the protective film described herein.The thermoplastic grid may also comprise a fabric, grid, nonwoven or mesh fibrous material coated or impregnated with at least one thermoplastic material. Preferably, the fibrous material is selected from polymeric materials, glass fibers and carbon fibers. This may further increase the stability and durability of the protective film according to the present disclosure. Furthermore, it is preferred that the thermoplastic grid exhibits a thickness in the range of 0.1-1.4 mm, preferably 0.2-1.2 mm, more preferably 0.3-1 mm. The thermoplastic grid has a thickness of 50-450 g / m. 2 , preferably 80 to 350 g / m 2 , more preferably 100 to 300 g / m 2 It is further preferred to indicate an areal weight according to DIN EN 12127 in the range

[0023] It has also been found that the addition of at least one endothermic filler to the protective film described herein can be advantageous. Endothermic filler has the effect of absorbing the heat released by thermal runaway events, and thus can at least partially and locally reduce the temperature. This can be advantageous in that the protective film described herein can last longer and / or the temperature of the back side of the film can be lower compared to a film that does not contain any endothermic filler. Therefore, it is preferred that at least one protective layer further comprises at least one endothermic filler. Additionally or alternatively, the protective film described herein further comprises at least one additional layer comprising at least one endothermic filler, and preferably at least one additional layer comprises silicone rubber. In this regard, the at least one endothermic filler may be selected from the group consisting of sodium metasilicate pentahydrate, ammonium dihydrogen phosphate, inorganic carbonates, preferably calcium magnesium carbonate and calcium magnesium silicate, metal hydroxides, preferably aluminum hydroxide and magnesium hydroxide, inorganic compounds containing water of crystallization, preferably aluminum hydroxide, magnesium carbonate, magnesium oxide, Mg(OH) 2 4MgCO 3 4H 2 O, MgCl 2 5Mg(OH)2 7H 2 O, and any combinations and mixtures thereof.

[0024] It has further been found that it may be advantageous to add an inorganic filler having a low density and / or a low thermal conductivity to at least one protective layer of the protective film described herein. In particular, a lower density may be advantageous to reduce the weight of the protective film, and a material with a low thermal conductivity may have the advantage of providing a protective film that provides a certain insulation and protection, respectively. It is therefore preferred that at least one protective layer comprises an inorganic filler having a low density and / or a low thermal conductivity. In this regard, it is preferred that the inorganic filler has a thermal conductivity TC of less than 0.2 W / mK, preferably less than 0.15 W / mK, more preferably less than 0.1 W / mK, even more preferably less than 0.8 W / mK at 25°C according to ASTM D5470. It is further preferred that the inorganic filler has a thermal conductivity TC of more than 0.001 W / mK at 25°C according to ASTM D5470. In terms of density, the inorganic filler has a thermal conductivity of less than 3.5 g / cm 3 less than 3.2 g / cm 3 less than 3 g / cm 3It is preferred that the filler exhibits a bulk density of less than 1 W / mK. Although any inorganic material falling within these parameters can be used, it is preferred that the inorganic filler is selected from diatomaceous earth, perlite and fumed silica, and any combinations and mixtures thereof. These compounds are readily available in large quantities, are non-toxic, and are compatible with the at least one silicate compound and silicone rubber in the at least one protective layer described herein. Preferably, the inorganic filler and the at least one silicate compound are contained in the at least one protective layer in a total amount as defined in any one of claims 1 to 3. In summary, it is desirable to have a protective film with low thermal conductivity. This can be achieved by the protective film according to the present disclosure. Thus, the protective film described herein can advantageously exhibit a thermal conductivity according to ASTM D5470 of less than 1 W / mK, preferably less than 0.8 W / mK, more preferably less than 0.7 W / mK.

[0025] It is also preferred that the protective film described herein further comprises at least one metal mesh. This has the advantage of improved mechanical stability, especially against blast waves, and can also aid in the dissipation of thermal energy from the impact point. The at least one metal mesh may be mounted on the at least one protective layer or embedded within the at least one protective layer. Preferably, the metal of the metal mesh is selected from steel, titanium, aluminum, and any combination thereof, preferably selected from steel and aluminum, more preferably selected from steel. The at least one metal mesh preferably has a thickness in the range of 0.3 mm to 2 mm, preferably 0.5 to 1.8 mm, more preferably 0.6 to 1.7 mm. The metal mesh may exhibit a mesh width in the range of 0.5 to 3 mm, preferably 0.7 to 2.8 mm, more preferably 0.9 to 2.5 mm.

[0026] The protective film according to the present disclosure preferably has a thickness of at least 0.5 mm, preferably at least 0.6 mm, more preferably 0.7 mm. It is also preferred that the protective film described herein has a thickness of at most 3.5 mm, preferably at most 3.2 mm, more preferably at most 3 mm. Preferably, the protective film has a thickness in the range of 0.5-3.5 mm, preferably 0.6-3.2 mm, more preferably 0.7-3 mm. Smaller thicknesses may not provide the desired protection in the event of a thermal runaway event, and larger thicknesses may be considered impractical for many applications. Generally, the protective film described herein has a thickness of at least 900 g / m 2 , more preferably at least 1000 g / m 2 , more preferably at least 1100 g / m 2 , and even more preferably at least 1200 g / m 2 Preferably, the thermal runaway protection film also exhibits an areal weight of up to 8000 g / m 2 , preferably up to 7000 g / m 2 , more preferably up to 6000 g / m 2 Therefore, the thermal runaway protection film described herein has an area weight of 900 to 8000 g / m 2 , preferably 1000 to 7000 g / m 2 , more preferably 1100 to 6000 g / m 2 It is preferable that the surface area weight is in the range of 100 mm to 200 mm.

[0027] The protective film according to the present disclosure can advantageously provide thermal insulation. Also, the protective film described herein can further provide electrical insulation against arcing. Both thermal insulation against arcing and electrical insulation are highly advantageous in the event of thermal runaway in a lithium-ion battery or battery module. In this regard, the protective film preferably exhibits a dielectric breakdown strength, direct current, according to DIN EN ISO 60243-2 (DC) in the range of 1-20 KV / mm.

[0028] For transport and application purposes, the protective film preferably further comprises at least one liner on at least one of its major surfaces. Liners for silicone films are well known to those skilled in the art and are readily commercially available. The protective film according to the present invention may be provided in the form of a sheet or in the form wound into a roll, preferably in a level-wound roll. The latter is particularly advantageous as it is suitable for application by automated equipment, especially high-speed robotic equipment, which is highly desirable for large-scale industrial production operations.

[0029] The present disclosure also provides a lithium ion battery module comprising a protective film according to the present disclosure and a lithium ion battery comprising the protective film, i.e., a lithium ion battery module as described herein.

[0030] The present disclosure provides a method for preparing a thermal runaway protection film, comprising: (i) incorporating at least one silicate compound into a silicone; (ii) forming at least one protective layer from the silicone composition obtained in step (i); (iii) optionally drying or curing the at least one protective layer obtained in step (ii), thereby obtaining a thermal runaway protection film; The at least one silicate compound is contained in the at least one protective layer in an amount of at least 40% by weight, based on the total weight of the at least one protective layer.

[0031] It is understood that the materials, amounts, thicknesses and other parameters disclosed herein in relation to the protective layer and protective film described herein also apply without limitation to the method according to the present disclosure.The incorporation of at least one silicate compound into silicone, preferably silicone rubber, can be carried out by means well established in the art.The formation of at least one protective layer can be achieved by calandring, layering, coating and / or spraying the silicone composition obtained in step (i).

[0032] Finally, the present disclosure provides the use of the protective film described herein for preventing or mitigating thermal runaway events in lithium ion batteries. Preferably, the lithium ion battery is a battery in an automotive, commercial transportation, marine, structural or aerospace application. In particular, the battery is preferably a vehicle, building or bicycle battery. EXAMPLES

[0033] The present disclosure will be further described, but is not intended to be limited thereto. The following examples are presented to illustrate certain embodiments, but are not intended to be limiting in any way. Prior to this, some test methods used to characterize materials and their properties are described. All parts and percentages are by weight unless otherwise indicated.

[0034] Test Method Torch and Grit Test (T>) Each sample was mounted on either 0.7 mm thick galvanized steel or stainless steel sheet with VHB tape (3M Company). The samples were positioned 44.5 mm from the nozzle of a Champion Bench hydrogen torch burner obtained from Bethlehem Apparatus Company Inc (Hellertown, PA, USA). A thermocouple (TC0) was positioned 31.8 mm from the burner nozzle and another thermocouple was placed at the center of the backside of the steel sheet. The blaster gun was loaded with 120 grit aluminum oxide unformed media and aligned with the nozzle of the torch at the same distance (44.5 mm) from the sample. The torch of the Champion Bench Burner was adjusted to 1200°C. The media blaster gun was then operated at 172.4 kPa or 344.7 kPa. The samples were exposed to either 1) 12 blast cycles at target locations, each lasting 15 seconds, with a 10 second active blast time and a 5 second inactive blast time, or 2) one blast cycle at three target locations spaced 1.5 inches (38.1 mm) apart, lasting 20 seconds, with a 5 second inactive blast time, followed by a 10 second active blast time, then a 5 second inactive blast time. Sample testing was stopped if holes were visible in the layers of the barrier article, caused by either burn-through or media blasting.

[0035] Dielectric Strength Test The dielectric strength of the materials was measured with direct current in accordance with DIN EN 60243-2. ​​The results were determined as KV / mm.

[0036] Free Fall Impact Test A simple free-fall impact test (expected from road shock, acceleration and vibration in automotive applications) was performed to evaluate the mechanical stability of the samples. The following protocol was followed: Examples and Comparative Examples samples, also used in the Torch & Grit test, were dropped from a height of 1.8 m onto the floor. This procedure continued for 20 cycles. After each cycle, the samples were visually inspected for damage such as cracks, parts falling off, or structural breakage.

[0037] preparation A structure was made with the following layers: 1.)ECR glass Vlies 50g / m 2 0.5mm thickness 2.) Silicone rubber with silicate compound filler 3.) Optionally, fabric or metal mesh 4.) Silicone rubber, optionally with silicate compound filler 5.) ECR glass Vlies 50g / m 2 0.5mm thickness

[0038] Layers 1.) and 2.) were used to encase layers 2.) and 4.) to allow for proper handling during manufacturing until drying was complete.

[0039] In general, the protective layer was formed by compounding the silicate compound with a silicone rubber (either Wacker Silgel 612 or a two-component silicone rubber) and coating the resulting silicone rubber / silicate compound filler composition onto a polymer carrier at the desired thickness. When a fabric or metal mesh was used (layer 3. above), the silicone rubber / silicate compound filler composition was coated on both sides of the fabric or metal mesh. ECR glass fleece was then applied to both sides. Finally, the structure was dried at room temperature for 3 hours. [Table 1] [Table 2] [Table 3]

[0040] Films consisting of layers 1), 2) and 5) above were produced using formulations 1, 2 and 3 to obtain examples 1, 2 and 3, respectively. As comparative example 1, a film containing layer 2.) without any silicate compound filler was used. Film samples were placed in an oven and tested for stability when exposed to different temperatures for 10 minutes. The results are summarized in Table 4. [Table 4]

[0041] Evaluations showed that Comparative Example 1, which does not contain any silicate compounds, was stable up to 400° C., but not at temperatures above that. In fact, the material of Comparative Example 1 collapsed and turned into SiO 2 at higher temperatures. 2 Only powder remained. In contrast, Examples 1, 2 and 3 survived exposure to temperatures up to 1200°C. [Table 5]

[0042] Formulation 4 was used to produce two further films, Example 4, which includes a steel wire mesh (layers 1.)-5) above), and Example 5, which does not include a metal mesh (i.e., as in Examples 1-3). Details of the films from Examples 5 and 6, as well as the test results of the torch and grit tests (following both procedures 1 and 2), are summarized in Table 6. [Table 6]

[0043] Both the films from Examples 4 and 5 survived both the torch and grit test procedures.

[0044] In Formulations 5 and 6, a portion of the silicate compound (e.g., mullite) was replaced with inorganic fillers having low thermal conductivity, namely, diatomaceous earth and perlite, respectively. Formulations 5 and 6 are summarized in Tables 7 and 8. [Table 7] [Table 8]

[0045] Following the procedures of Examples 1-3, Formulations 5 and 6 were formed into Films 6 and 7, respectively. The results are summarized in Table 9. [Table 9]

[0046] The films of Example 6 and Example 7 were then tested with the torch and grit test (Procedure 1). The backside temperature was also measured. In Table 10, this is compared with the results obtained from performing the same test with the film of Example 5. [Table 10]

[0047] Examples 6 and 7, which have inorganic fillers with low density and low thermal conductivity, show lower sample backside temperatures in torch and grit tests than Example 5. Also, the mechanical performance and blast resistance are somewhat reduced compared to Example 5. However, the mechanical performance and blast resistance may already be sufficient for many applications. This makes it possible to provide blast resistance together with thermal insulation.

[0048] The film according to Example 5 was then further used by applying a layer containing an endothermic filler of Formulation 7 and Formulation 8, respectively. Formulations 7 and 8 are summarized in Tables 11 and 12. [Table 11] [Table 12] [Table 13]

[0049] Examples 4, 5, 8 and 10 performed well in terms of not burning through the plate in the torch and grit test, whereas Examples 9 and 11 eventually burned through the plate, but the holes in each were small (10mm and 8mm respectively) and the overall performance was considered very good, especially considering the fact that no wire mesh was used.

[0050] Furthermore, a thermoplastic scrim was used in the manufacture of the protective film described herein. As the thermoplastic scrim, a polypropylene scrim under the trade name "Delcotex Delicomp" manufactured by Delcotex Delius Techtex GmbH & Co. KG, Germany was used. In particular, Delcotex 86061 has a density of 200 g / m 2 It is a scrim type having an areal weight according to DIN EN 12127 of 270 g / m2 and a thickness according to DIN EN ISO 5084 of 0.8 mm. Delcotex 86072 is also a scrim type having an areal weight according to DIN EN 12127 of 270 g / m2 and a thickness according to DIN EN ISO 5084 of 0.8 mm. 2 Formulation 4 described herein was used to prepare a film having a thickness of about 3 mm and the following structure: First structure: Layer 1: Formulation 4 Layer 2: Thermoplastic grid Layer 3: Formulation 4 Second structure: Layer 1: Formulation 4 Layer 2: Thermoplastic grid laminated to layer 1.

[0051] After preparation, all films thus obtained were flexible, bendable and moldable into 3D shapes. Different shapes were created by heating the samples with a hot air gun and initiating the thermal activation of the thermoplastic grid. After cooling the material, the desired shape was frozen in. It makes it possible to form the protective films described herein into specific shapes and achieve three-dimensional stability after thermal activation.

Claims

1. A thermal runaway protection film for a lithium ion battery, A thermal runaway protection film comprising at least one protective layer comprising at least one silicone and at least one silicate compound in an amount of at least 40 wt % based on the total weight of the at least one protective layer.

2. 2. The thermal runaway protective film of claim 1, wherein the at least one protective layer comprises at least 45 wt. %, preferably at least 50 wt. %, more preferably at least 60 wt. %, and even more preferably at least 70 wt. % of the at least one silicate compound, based on the total weight of the at least one layer.

3. The thermal runaway protection film of claim 1 , wherein the at least one silicone is at least one silicone rubber.

4. 2. The thermal runaway protective film of claim 1, wherein the at least one silicate compound is selected from kaolin, metakaolin, mullite, wollastonite, and any combinations and mixtures thereof, preferably metakaolin, mullite, and wollastonite, and any combinations and mixtures thereof, more preferably mullite and / or wollastonite, even more preferably mullite.

5. The thermal runaway protection film of claim 1 , further comprising at least one polymer grid, preferably a thermoplastic grid.

6. 6. The thermal runaway protection film of claim 5, wherein the thermoplastic grid comprises at least one thermoplastic material selected from acrylonitrile-butadiene-styrene (ABS), polyamide (PA), polylactate (PLA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyether ether ketone (PEEK), polyvinyl chloride (PVC), and any combinations and mixtures thereof, preferably polypropylene and polyamide.

7. The thermal runaway protective film of claim 1, wherein the at least one protective layer further comprises at least one endothermic filler, or the thermal runaway protective film further comprises at least one additional layer comprising at least one endothermic filler, preferably wherein the at least one additional layer comprises silicone rubber.

8. 10. The thermal runaway protection film of claim 1, wherein the thermal runaway protection film exhibits a thermal conductivity according to ASTM D5470 of less than 1 W / mK, preferably less than 0.8 W / mK, more preferably less than 0.7 W / mK.

9. 2. The thermal runaway protection film of claim 1, wherein the battery protection film has a thickness of 0.5 to 3.5 mm, preferably 0.6 to 3.2 mm, more preferably 0.7 to 3 mm.

10. 1. A method for preparing a thermal runaway protection film, comprising the steps of: (i) incorporating at least one silicate compound into a silicone; (ii) forming at least one protective layer from the silicone composition obtained in step (i); (iii) optionally drying or curing the at least one protective layer obtained in step (ii), thereby obtaining a thermal runaway protection film; The method of claim 1, wherein the at least one silicate compound is contained in the at least one protective layer in an amount of at least 40% by weight, based on the total weight of the at least one protective layer.