Composite thermal management sheet, method of manufacture, and articles using the same

Abstract

The composite thermal management sheet for a battery includes a silicone foam layer; and a reactive filler composition disposed within the silicone foam layer, the reactive filler composition including a first filler that decomposes upon initial exposure to heat to produce water; and a second filler different from the first filler, where the second filler forms a thermal barrier layer with a decomposition product of the first filler, absorbs water, or both.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims the interests of U.S. Patent Application No. 63 / 158,675, filed on 9 March 2021, which is incorporated herein by reference in its entirety. [Background technology]

[0002] This application relates to a composite thermal management sheet for use in batteries, particularly lithium-ion batteries, for use in delaying or preventing thermal runaway. This application further relates to a composite thermal management sheet, a battery component, and a method for manufacturing a battery including the composite thermal management sheet.

[0003] Demand for electrochemical energy storage devices such as lithium-ion batteries is constantly increasing due to the growth of applications such as electric vehicles and power grid energy storage systems, as well as other multi-cell battery applications such as electric motorcycles, uninterruptible battery systems, and lead-acid battery replacements. As their use increases, methods for thermal management are desired. In large-scale applications such as power grid storage and electric vehicles, numerous electrochemical cells are often used connected in series and parallel arrays, which can lead to thermal runaway. When a cell enters thermal runaway mode, the heat generated by the cell can trigger thermal runaway propagation reactions in adjacent cells, potentially causing a cascade effect that can ignite the entire battery.

[0004] Attempts have been made to reduce thermal runaway in batteries, but many have drawbacks. For example, modifying the electrolyte by adding flame-retardant additives or using an inherently non-flammable electrolyte has been considered, but these methods can adversely affect the electrochemical performance of the battery. Other methods for thermal management or preventing cascading thermal runaway include increasing the amount of insulation between cells or between groups of cells to reduce heat transfer during thermal events. However, these methods may limit the upper limit of the achievable energy density. [Overview of the project] [Problems that the invention aims to solve]

[0005] With the increasing demand for batteries with improved thermal management or reduced risk of thermal runaway, there is a corresponding need for methods and components for use in batteries that prevent or delay the spread of heat, energy, or both to surrounding cells. [Means for solving the problem]

[0006] In one embodiment, the composite thermal management sheet for a battery comprises a silicone foam layer; and a reactive filler composition disposed within the silicone foam layer, the reactive filler composition comprising a first filler that decomposes upon initial exposure to heat to produce water; and a second filler different from the first filler, wherein the second filler forms a thermal barrier layer with the decomposition products of the first filler, absorbs water, or both.

[0007] The battery assembly includes the composite thermal management sheet described above, which is placed on the surface of the electrochemical cell.

[0008] A battery including the above assembly is also disclosed.

[0009] The above and other features are illustrated by the following figures, detailed description, examples and claims.

[0010] The following is a brief description of the drawings, which are provided for illustrative purposes only and not to limit the exemplary embodiments disclosed herein. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing an embodiment of a composite thermal management sheet. [Figure 2] This is a schematic diagram showing the configuration of a composite thermal management sheet located between two cells. [Figure 3] This is a schematic diagram showing the configuration of a composite thermal management sheet located between two electrochemical cells. [Figure 4] This is a schematic diagram showing the configuration of a composite thermal management sheet located in a cell array. [Figure 5] This is a schematic diagram showing an embodiment of a battery assembly including a composite thermal management sheet. [Figure 6] This is a schematic diagram of the hot plate testing equipment. [Figure 7] This figure shows the deformed barrier layer located between the hot plate and the top layer of the hot plate testing equipment. [Figure 8] This is a photograph showing a borosilicate thermal barrier layer formed from a reactive filler composition containing borax and zinc borate. [Figure 9] This graph shows the results of the simulated thermal runaway tests for Comparative Example 1 and Examples 1-6, with temperature (°C) versus time (minutes (min)). [Figure 10A] This is a schematic diagram of the disassembled and assembled first equipment for the nail penetration test. [Figure 10B] Figure 10A is a schematic diagram, not an exploded view. [Figure 11] This graph shows the results of the nail penetration test for Comparative Example 3 and Example 7, with temperature (°C) versus time (min). [Figure 12] This graph shows the results of the nail penetration test for Comparative Examples 2 and 3 and Example 7, which have different thicknesses, as well as the voltage (V) versus time (min). [Figure 13]Graph of heat release rate (HRR) (watts / gram (W / g)) versus temperature (°C) for Comparative Example 3. [Figure 14] Graph of HRR (W / g) versus temperature (°C) for Example 7. [Figure 15] Graph of HRR (W / g) versus temperature (°C) for Example 8. [Figure 16A] Exploded assembly schematic diagram of the second equipment for the nail penetration test. [Figure 16B] Schematic diagram that is not the exploded assembly diagram shown in Fig. 16A. [Figure 17] Graph of temperature (°C) versus time (seconds (s)) showing the results of the nail penetration test for Comparative Example 3. [Figure 18] Graph of temperature (°C) versus time (s) showing the results of the nail penetration test for Example 7. [Figure 19] Photo of Example 7 after the nail penetration test. [Figure 20] Graph of temperature (°C) versus time (s) showing the results of the nail penetration test for Example 8.

Mode for Carrying Out the Invention

[0012] Thermal management in batteries, for example, preventing thermal runaway in batteries, particularly those containing a large number of electrochemical cells, is a difficult problem because cells adjacent to a cell experiencing thermal runaway can absorb enough energy from that event to cause their designed operating temperature to exceed, and the adjacent cells can also trigger thermal runaway. This propagation that initiates the thermal runaway event causes a chain reaction where cells cascade into a series of thermal runaways, and there is a possibility that a cell can ignite adjacent cells. Achieving effective thermal management performance in a sheet having a very thin total thickness, for example, 30 millimeters (mm) or less, or 20 mm or less, or 15 mm or less, or 10 mm or less, or 8 mm or less, or 6 mm or less, has been particularly difficult. Thin sheets are increasingly desired to reduce the size and mass of articles and save materials.

[0013] The inventors have found that a composite thermal management sheet comprising a silicone foam and a reactive filler composition can be used to suppress or reduce the intensity of such cascading thermal runaway events. The reactive filler composition is formulated so that, upon exposure to a heat source, the filler composition first generates and absorbs water, thereby mitigating heat transfer to adjacent cells. In one embodiment, the water can be trapped or desorbed, resulting in water reuse. In another embodiment, upon continued exposure to heat, the flexible silicone layer and the reactive filler composition can form a thermal barrier layer that can further mitigate heat transfer to adjacent cells.

[0014] Unexpectedly, it was found that the use of reactive filler compositions is particularly useful in the production of very thin composite thermal management sheets with good thermal insulation properties, i.e., 30 mm or less, or 20 mm or less, or 15 mm or less, or 10 mm or less, or 8 mm or less, or 6 mm or less. Composite thermal management sheets can have additional advantageous properties, such as good puncture resistance. Composite thermal management sheets can be subjected to numerous heating and cooling cycles and still provide good thermal insulation. Composite thermal management sheets can further provide pressure control to electrochemical cells and batteries. Composite thermal management sheets can be used in various parts of batteries to prevent thermal runaway. Composite thermal management sheets can further improve the flame resistance of batteries.

[0015] As described above, the composite thermal management sheet comprises a flexible porous layer and at least two fillers having specific properties. Figure 1 shows an embodiment in which the composite thermal management sheet 10 comprises a flexible silicone foam layer 12 having a first outer surface 14 and an opposite second outer surface 16. Although shown as flat, the contours of one, both, or all of the outer surfaces can be fitted tightly to the surface of an electrochemical cell.

[0016] The flexible silicone foam layer 12 further includes a plurality of openings, i.e., pores 18. The pores are defined by the internal surface 20 of the flexible foam material. The pores may be interconnected or discrete. A combination of interconnected and discrete pores may exist. The pores as a whole may be contained within the sheet, or at least a portion of the pores may open to the surface of the sheet, enabling communication with the surrounding environment. In one embodiment, at least a portion of the pores are interconnected, and at least a portion of the pores are open, allowing the passage of air, water, water vapor, etc., from a first outer surface 14 to an opposite second outer surface 16, which is referred to herein as an "open-cell foam." In another embodiment, the foam may be a "closed-cell foam," where the pores may or may not be interconnected, and are substantially not open to the surface of the sheet or are completely closed, thereby substantially preventing the passage of air, water, water vapor, etc., from one outer surface to the other. In one embodiment, the foam is substantially closed-cell foam or completely closed-cell foam.

[0017] Referring further to Figure 1, the filler composition comprises two or more different fillers 22, 24 distributed within the flexible silicone foam layer 12. The fillers can be distributed basically uniformly or in a gradual manner, increasing, for example, from the first outer surface 14 to the second outer surface 16. As used herein, the phrase “placed within” may mean that the reactive filler composition is distributed within the matrix of the silicone foam layer as shown in Figure 1. Furthermore, as used herein, the phrase “placed within” may mean that the reactive filler composition can be located within the pores 18 of the silicone foam layer, for example, coating the inner surface 20 of the flexible foam material or being located within the pores in the form of fine particles. Some of the pores in the silicone foam layer may contain the reactive filler composition, or basically all or all of the pores may contain the reactive filler composition. Each pore containing the reactive filler composition may independently be partially filled, basically completely filled, or completely filled.

[0018] The silicone foam is selected to be inert to the normal operating conditions of batteries such as lithium-ion batteries, to serve as a carrier for reactive filler compositions, and to provide a silicon source for the formation of a thermal barrier layer as described in detail below. Various silicone foams are known in the art and can be used. In some embodiments, the silicone foam includes poly(dialkylsiloxane), for example, poly(dimethylsiloxane).

[0019] A reactive filler composition comprises at least two different fillers having specific properties. As can be understood from the following discussion, when used in relation to a filler composition, the term “reactive” includes both chemical reactions, e.g., the breakdown of existing chemical bonds or the formation of new chemical bonds, and physical processes, such as the breakdown and formation of hydrogen bonds. The type and amount of each of the at least two fillers in a reactive filler composition are primarily selected to produce water upon exposure to heat. As used herein, “produce water” can mean, for example, the release of water from a hydrate, or, for example, the formation of water by a chemical reaction process. Furthermore, the water produced can be in the form of liquid or water vapor. As used herein, “water” therefore includes liquid water, water vapor, or a combination thereof. As used herein, “heat” means heat above the normal operating temperature of the battery, and includes heat produced by a flame or contact with a flame. Such temperatures can be 100°C or higher, or 200°C or higher, or 300°C or higher, or 500°C or higher. While not constrained by theory, it is believed that the generation of water from the reactive filler composition can provide a thermal barrier by absorbing, redistributing, or evaporating heat.

[0020] The type and amount of each of at least two fillers can be further selected to form a thermal barrier layer in situ by exposure to heat, absorption of water, or both. As used herein, “thermal barrier layer” is a layer that is physically, chemically, or both physically and chemically distinct from the composite thermal management sheet and is capable of providing a conductive or convective thermal barrier to heat, flame, or both. The “thermal barrier layer” includes char layers or water-swellable polymers, the term as may be used in the art. The inventors have found that without the in-situ formation of a thermal barrier layer, the transport of hot air and water vapor through the flexible porous layer, including the cell wall, can result in rapid heat transfer to adjacent cells. Although not bound by theory, the in-situ formation of a thermal barrier layer suggests that hot air and water generated on the non-functioning cell side of the composite thermal management sheet are either trapped on the non-functioning cell surface, or inside the composite thermal management sheet, or both. This protects adjacent cells by preventing pressure generation in the thermal barrier layer and preventing convective heat transfer, conductive heat transfer, or both to adjacent cells.

[0021] At least two types of fillers are preferably in particulate form to allow for easy incorporation into the silicone foam during its fabrication. As described above, the particulate reactive filler composition can be located within the silicone matrix of the silicone foam layer, within the pores of the silicone foam layer, or both. Some of the pores in the silicone foam layer may contain the particulate reactive filler composition, or basically all or all of the pores may contain the particulate reactive filler composition. Each pore containing the particulate reactive filler composition may independently be partially filled, basically completely filled, or completely filled. In embodiments where the particles of the reactive filler composition are large relative to the diameter of the pore, or where the pore is basically or completely filled with a plurality of smaller particles, the movement of particles within the pore may be limited. In this embodiment, the particulate reactive filler composition can be located in the pores during the fabrication of the layer (for example, by including the particulate reactive filler composition in the composition used to form the silicone foam layer), or the particulate reactive filler composition can be impregnated into the pores after the fabrication of the silicone foam layer using a suitable liquid carrier, vacuum, or other known method.

[0022] Different combinations of reactive filler compositions, including those of different types, forms, or arrangements, can be used. For example, a reactive filler composition in the form of fine particles within the pores of a silicone foam layer can be used in combination with a reactive filler composition of fine particles distributed within the silicone foam layer.

[0023] The reactive particles or particles may be irregular or regular, and may have any shape, such as nearly spherical, spherical, or plate-like. A key characteristic is that most, essentially all, or all particles have a maximum dimension less than the thickness of the layer or pore in which they are located, in order to give the layer a smooth surface. Therefore, the specific diameter used depends on the position of the particles. Particles with two, three, or higher-order distribution modes can be used. For example, if the filler particles are present in the matrix of the silicone foam layer and in the pores of the silicone foam layer, particles with a bimodal distribution may be present.

[0024] At least two of the fillers are different from each other and are at least two of the following: aluminum trihydrate, ammonium nitrate, borax, hydrated sodium silicate, magnesium hydroxide, magnesium carbonate hydroxide pentahydrate, trimagnesium phosphate octahydrate, zinc borate, superabsorbent polymer, or water glass.

[0025] Fillers capable of generating water upon exposure to heat include various hydrated inorganic fillers such as aluminum trihydrate (also known as aluminum trihydroxylate or ATH), borax (sodium tetraborate pentahydrate), hydrated sodium silicate, magnesium carbonate hydroxide pentahydrate, trimagnesium phosphate octahydrate; superabsorbent polymers; and water glass. Combinations of the above can be used. Hydrated inorganic fillers and water glass can be represented by different chemical formulas, and it is understood that the above includes a variety of formulas. Certain hydrated inorganic fillers known to be used as phase-change materials that release water at lower temperatures (e.g., below 100°C or below 200°C) to prevent phase change at normal operating temperatures are not used.

[0026] Fillers that can participate in the formation of a thermal barrier layer, absorb water, or both include various inorganic fillers containing sodium, silicon, and boron. A single filler can perform both water generation and participate in the formation of a thermal barrier layer. Exemplary fillers of this type may include ATH, ammonium nitrate, borax, hydrated sodium silicate, magnesium hydroxide, magnesium carbonate hydroxide pentahydrate, trimagnesium phosphate octahydrate, zinc borate, superabsorbent polymers, or combinations thereof.

[0027] In the first embodiment, the reactive filler composition comprises ATH and zinc borate. This combination generates water upon exposure to a heat source. The water can expand the silicone foam and provide counterpressure. Although not bound by theory, the generation of water can absorb heat and prevent thermal runaway. Further heat can be absorbed by converting liquid water to water vapor. The heat capacities of ATH and zinc borate can further contribute to heat absorption. A porous thermal barrier layer can be formed upon exposure to a heat source.

[0028] In a second embodiment, the first and second fillers are selected to both generate water and form a borosilicate glass thermal layer in place upon exposure to heat. In this embodiment, the first and second fillers may include a combination of borax and hydrated sodium silicate. Borax and hydrated sodium silicate can generate water and supply sodium and boron to form borosilicate glass. Decomposition of the flexible silicone layer can provide silicon to form borosilicate glass. In this embodiment, a combination of ATH, zinc borate and hydrated sodium silicate can also be used. Although not bound by theory, it is assumed that during exposure to a heat source, the composite thermal management sheet absorbs heat due to the heat capacity of the silicone and borax; the heat of water generation and any evaporation from the borax; and the endothermic formation of the borosilicate glass. Exposure to a heat source can cause the thermal barrier layer to form and expand.

[0029] Advantageously, a combination of borax and zinc borate can be used in the reactive filler composition. Surprisingly, it has been found that when borax and zinc borate are used, the borosilicate glass thermal barrier layer undergoes both expansion and deformation, forming a flexible yet rigid layer. The deformation can act as a normal force against adjacent expanding battery cells, reducing or suppressing damage caused by expanding cells entering thermal runaway. While not constrained by theory, it is thought that the generation of a normal force due to expansion pressure and the shape of the char layer can further prevent convective and conductive heat transfer.

[0030] In these embodiments, the components and concentrations of the reactive filler composition can be selected to provide a gradual release of water, thereby providing continuous heat reduction. For example, during a hot plate test of a filler composition containing a combination of borax and zinc borate, it was found that heat from the hot plate diffused into the flexible foam, generating water vapor first from the borax at 140°C and then from the zinc borate at 340°C. Although not bound by theory, it is thought that the initial release of water from the borax initiates and maintains the formation of a heat barrier layer, influencing the thickness of the final borosilicate glass heat barrier layer and the pressure exerted thereon. This process also absorbs heat due to the heat capacity of the silicone, zinc borate, and borax; the heat of water generation and any evaporation from both zinc borate and borax; and the endothermic formation of the borosilicate glass. Furthermore, the deformation of the composite layer provides resistance to heat transfer.

[0031] In another example of stepwise water release, a reactive packing composition containing borax and aluminum trihydrate can generate water vapor first from borax at 140°C and then from the decomposition products of ATH at 220°C.

[0032] Another reactive filler composition capable of providing a stepwise water release may include borax, ATH, and zinc borate. This combination can provide a three-step water generation system that produces water from borax at 140°C, from ATH at 220°C, and from zinc borate at 340°C.

[0033] In a third embodiment, the reactive filler composition is further formulated to absorb water that can be trapped or released (reused). In this embodiment, water absorption provides an additional mechanism for delaying, reducing, or preventing convective heat transport. Water absorption can further contribute to the expansion of the composite heat conduction layer, providing additional pressure relief. In this embodiment, the reactive filler composition includes a filler that generates water upon exposure to heat and a filler that can absorb the generated water. The water can be permanently absorbed (i.e., trapped) or released (desorbed), allowing for water reuse.

[0034] In this embodiment, the water-generating filler may include borax, ATH, magnesium hydroxide pentahydrate (MDH), or a combination thereof.

[0035] The filler capable of absorbing the generated water includes a superabsorbent polymer (SAP). Under certain conditions, the SAP absorbs and traps water, where the trapped water is released only by the decomposition of the SAP. Under other conditions, the SAP can absorb and release water without decomposition. Superabsorbent polymers known in the art include: hydrolysis products of starch grafted with acrylonitrile homopolymers or copolymers, e.g., hydrolyzed starch-polyacrylonitrile; starch grafted with acrylic acid, acrylamide, polyvinyl alcohol (PVA), or combinations thereof, e.g., starch-g-poly(2-propenamide-co-2-sodium propenate); hydrolyzed starch-polyacrylonitrile ethylene-maleic anhydride copolymer; crosslinked carboxymethylcellulose; acrylate homopolymers and copolymers thereof, e.g., poly(sodium acrylate) and poly(acrylate-co-acrylamide), especially poly(sodium acrylate-co-acrylamide); hydrolyzed acrylonitrile homopolymers; homopolymers and copolymers of 2-propenic acid, e.g., poly(2-sodium propenate) and poly(2-propenamide-co-2-sodium propenate) or poly(2-propenamide-co-2-potassium propenate); crosslinked modified polyacrylamide; polyvinyl alcohol copolymers, crosslinked polyethylene oxide; and others. It is possible to use combinations of two or more different SAPs.

[0036] The SAP is preferably an electrolyte such as a poly(acrylate) salt, for example, poly(sodium acrylate). The SAP can have a swelling ratio of 15:1 to 1000:1. A higher ratio is preferable. When absorbing water, the SAP traps the water and expands. This expansion can act as a normal force against adjacent expanding battery cells, reducing or suppressing damage caused by expanding cells that have entered thermal runaway.

[0037] SAP can, in some cases, be hydrated with water in water (by spraying, immersion, or other methods). For example, SAP can be hydrated before being incorporated into a silicone foam, or a composite thermal management layer containing SAP can be immersed in water at room temperature for 24 hours.

[0038] While not constrained by theory, in this embodiment, it is assumed that water is first generated from the filler as the temperature rises (at various temperatures, depending on the case) as described above. The water is absorbed by the SAP. In one embodiment, the water absorbed by the SAP is trapped and not released. In another embodiment, the water absorbed by the SAP absorbs heat and is then released, either present in a system including an electrochemical cell or absorbed by other dehydrated SAP at another location on the composite thermal control sheet. Finally, borosilicate glass can be formed as a continuous, flexible thermal barrier layer.

[0039] Another filler that can be used to absorb water is water glass. As is known in the art, water glass is water-soluble and contains sodium oxide (Na2O) and silicon dioxide (silica, SiO2). Under certain conditions, water glass can absorb water and trap it, or absorb water and release it.

[0040] In yet another embodiment, the reactive filler composition may be formulated to produce water glass in situ without decomposition of the flexible silicone layer. In this embodiment, the filler may include borax and hydrated sodium silicate. Other components may be present, such as aluminum trihydrate, magnesium hydroxide, magnesium carbonate hydroxide pentahydrate, or ammonium nitrate, or combinations thereof. Although not bound by theory, it is thought that heat diffuses into the silicone foam and produces water at various temperatures depending on the combination of water-producing fillers used. Residual ions derived from the decomposition of the water-producing fillers can form Lewis acids or Lewis bases, which can react with hydrated sodium silicate to form water glass. The water can be released and reused. Alternatively, since the water evaporates due to heating, the water glass solution can solidify to provide a glassy solid that can serve as an inner or outer heat transfer barrier layer for the silicone foam.

[0041] Composite thermal management sheets can be manufactured from silicone foam-forming compositions by methods known in the art. Reactive filler compositions can be incorporated into the silicone foam-forming composition before the reactive filler composition is foamed and cured. For example, a suitable silicone foam can be produced by the foaming reaction and curing of a silicone foam-forming composition containing terminally unsaturated polysiloxanes, such as those with vinyl groups and polysiloxanes with terminally hydride groups. Polysiloxanes for silicone foam formation can have a viscosity of 100 to 1,000,000 poise at 25°C. Polysiloxanes for silicone foam formation can have chain substituents such as hydride, methyl, ethyl, propyl, vinyl, phenyl, and trifluoropropyl, as well as terminally hydride and vinyl groups, in addition to hydroxyl, alkoxy, acyloxy, allyl, oxime, aminooxy, isopropeneoxy, epoxy, mercapto groups, or other known reactive end groups. It is also possible to have several polysiloxane-based polymers containing different functionalities or reactive groups to produce the desired foam. Silicone foams can also be produced by using several polysiloxanes having different molecular weights (e.g., bimodal or trimodal molecular weight distributions), insofar as the combined viscosity allows for the immediate incorporation and immediate fabrication of reactive filler compositions.

[0042] The silicone foam-forming composition may further contain a catalyst, such as a noble metal, preferably platinum. The catalyst can be deposited on an inert support such as silica gel, alumina, or carbon black. Various platinum catalyst inhibitors may also be present to control the reaction kinetics of the foaming and curing reactions in order to control the porosity and density of the silicone foam. Examples of such inhibitors include polymethylvinylsiloxane cyclic compounds and acetylene alcohols. These inhibitors should not interfere with foaming and curing in a way that destroys the foam. Chemical foaming agents may also be present.

[0043] In the production of silicone foam, the reactive component of the silicone foam-forming composition can be formulated in two parts: one part ("Part A") comprises a terminally unsaturated polysiloxane and a reactive filler composition, and, if used, a catalyst, inhibitor, and chemical blowing agent; the other part ("Part B") comprises a polysiloxane having hydride groups. The parts are measured and mixed and can be cast, for example, into a mold or a continuous coating line. Foaming and curing then occur either in the mold or on the continuous coating line. In an alternative production method, the reactive component of the silicone foam-forming composition can be put into an extruder together with the reactive filler composition and a chemical blowing agent, a physical blowing agent, or other additives, if used. A catalyst is then measured and put into the extruder to initiate the foaming and curing reactions. The use of a physical blowing agent such as liquid carbon dioxide or supercritical carbon dioxide in combination with a chemical blowing agent such as water can produce foam with a much lower density.

[0044] In some cases, the composite thermal management sheet can be immersed in water for a period of time, such as 24 hours, allowing the sheet to absorb water. The large heat capacity of liquid water can significantly delay heat transfer from one surface of the composite thermal management sheet to the other surface.

[0045] As described above, the amount of each filler in the reactive filler composition is adjusted to provide a desired degree of water generation and thermal barrier formation. Part A of the silicone foam-forming composition may contain 10 to 80 mass percent (wt%), 20 to 70 wt%, or 30 to 60 wt% of the reactive filler composition relative to the total mass of Part A, with the remainder of the composition of Part A being other components of Part A.

[0046] If the reactive filler composition contains ATH and zinc borate, Part A may contain 5-40 wt%, or 10-40 wt%, or 20-40 wt%, of ATH and 5-40 wt%, or 10-40 wt%, or 20-40 wt%, of zinc borate, respectively, relative to the total mass of Part A, with the remainder of the composition of Part A being the other components of Part A.

[0047] If the reactive filler composition contains borax and hydrated sodium silicate, Part A may contain 5-50 wt%, or 10-40 wt%, or 20-40 wt% borax and 5-30 wt%, or 10-30 wt% hydrated sodium silicate, respectively, relative to the total mass of Part A, with the remainder of the composition of Part A being the other components of Part A.

[0048] If the reactive filler composition contains ATH, hydrated sodium silicate, and zinc borate, Part A may contain 5-30 wt% or 10-20 wt% of ATH, 5-30 wt% or 10-30 wt% of hydrated sodium silicate, and 5-40 wt% or 10-30 wt% or 10-30 wt% or 20-30 wt% of zinc borate, respectively, relative to the total mass of Part A, with the remainder of the composition of Part A being the other components of Part A.

[0049] When the reactive filler composition contains borax and zinc borate, borax may be present in an amount of 5 to 45 wt%, or 10 to 40 wt%, preferably 15 to 35 wt%, most preferably 20 to 30 wt%, relative to the total mass of Part A, and zinc borate may be present in an amount of 5 to 40 wt%, or 10 to 40 wt%, preferably 15 to 35 wt%, most preferably 20 to 30 wt%, and the remainder of the composition of Part A shall be the other components of Part A.

[0050] When SAP is present in the reactive filler composition, Part A may contain SAP in amounts of 1 to 60 wt%, 5 to 35 wt%, or 10 to 35 wt% relative to the total mass of Part A, with the remainder of the composition of Part A being one or more different fillers and other components of Part A.

[0051] The composite thermal management sheet may contain other additives known in the art, such as processing aids, antioxidants, ozone degradation inhibitors, ultraviolet (UV) stabilizers or thermal stabilizers, dyes, pigments, flame retardants (e.g., organophosphorus-containing compounds), flame retardant synergies (e.g., antimony oxide), or combinations thereof. Thermal insulation fillers may be present to improve thermal insulation, heat absorption, or thermal flexibility. Exemplary thermal insulation fillers include ceramics such as silica, talc, calcium carbonate, clay, mica, and vermiculite, or combinations thereof. In another embodiment, thermally conductive fillers such as boron nitride, aluminum nitride, or combinations thereof may be present to improve thermal conductivity. Reinforcing particulate fillers may be present. Examples of reinforcing microparticle materials include lignin, carbon black, talc, mica, silica, quartz, metal oxides, glass microspheres (e.g., cenospheres, glass microspheres, e.g., borosilicate microspheres, or combinations thereof), polyhedral oligomer silsesquioxanes, substituted polyhedral oligomer silsesquioxanes, or combinations thereof. These additives can be added simultaneously with the reinforcing filler composition.

[0052] A silicone foam-forming composition can be foamed and cured in the presence of reinforcing fibers to provide a fiber-reinforced material. The reinforcing fibers may include polyester, polyacrylonitrile oxide, carbon, silica, polyaramid, polycarbonate, polyolefin, rayon, nylon, glass fibers (e.g., E-glass, S-glass, D-glass, L-glass, quartz fibers, or combinations thereof), high-density polyolefin, ceramic, acrylic resin, fluoropolymer, polyurethane, polyamide, polyimide, etc., or combinations thereof. The reinforcing fibers may be in any form, such as a woven or non-woven mat or tape. The mat or tape may have a thickness of, for example, 0.005 to 10 mm, or 0.05 to 8 mm, or 0.25 to 6 mm, or 0.5 to 10 mm, or 0.25 to 10 mm, or 0.5 to 10 mm, or 1 to 10 mm, or 1 mm to 6 mm. Combinations of reinforcing fine particle materials and reinforcing fibers can be used.

[0053] The composite thermal management sheet may have a thickness of 0.5 to 30 mm, or 0.5 to 20 mm, or 0.5 to 15 mm, or 0.5 to 10 mm, or 0.5 to 8 mm, or 1 to 6 mm, or 1 to 5 mm, or 1 to 4.5 mm, or 1 to 4 mm, or 1 to 3.5 mm, or 1 to 3 mm, or 1 to 2.5 mm. The disclosed composite thermal management sheet can provide equivalent or improved heat resistance at a thinner thickness compared to competing technologies for flame-retardant sheets. In some respects, for example, when a thermal barrier layer is formed, the thickness of the composite thermal management layer is preferably 1.5 to 30 mm, or 1.5 to 20 mm, or 1.5 to 15 mm, or 1.5 to 10 mm, or 1.5 to 8 mm, or 1.5 to 6 mm, or 1.5 to 5 mm, or 1.5 to 4.5 mm, or 1.5 to 4 mm, or 1.5 to 3.5 mm, or 1.5 to 3 mm, or 1.5 to 2.5 mm. Thicker composite thermal management sheets can provide greater pressure generation, deformation and borosilicate glass formation, and thereby improved thermal delay. In this embodiment, the thickness of the composite thermal management layer is preferably 1.5 to 30 mm, or 1.5 to 20 mm, or 1.5 to 15 mm, or 1.5 to 10 mm, or 1.5 to 8 mm, or 1.5 to 6 mm, or 2 to 30 mm, or 2 to 20 mm, or 2 to 15 mm, or 2 to 10 mm, or 2 to 8 mm, or 2 to 6 mm, or 3 to 0 mm, or 3 to 8 mm, or 3 to 6 mm.

[0054] In this embodiment, the composite thermal management sheet has a capacity of 5 to 65 pounds / cubic foot (lb / ft 3 )(1,041 kilograms / cubic meter (kg / m 3 )), or 5-55 lb / ft 3 (881kg / m 3 ), or 10-25 lb / ft 3 (400kg / m 3 ) can have a density of . In one embodiment, the foam is 5-30 lb / ft 3 (80~481kg / m 3 The composite thermal management sheet has a density of 5 to 99%, preferably 30%, or more relative to the total volume of the foam.

[0055] The composite thermal management sheet is flexible and can maintain its elastic behavior, i.e., the properties reflected in the compressive force deflection and compressive permanent set of the foam, over many cycles of compressive deflection in the life of the battery. Foams with good resistance to compressive permanent set provide cushioning and maintain their original shape or thickness under long-term loading. In an embodiment, the composite thermal management sheet has a compressive force deflection of 0.2 to 125 pounds per square inch (psi) (1 to 862 kilopascals (kPa)), or 0.25 to 20 psi (1.7 to 138 kPa), or 0.5 to 10 psi (3.4 to 68.9 kPa) as determined at 25% deflection each in accordance with ASTM D3574-17. The composite thermal management sheet has a compressive permanent set of 0 to 15%, or 0 to 10%, or 0 to 5% as determined at 70 °C in accordance with ASTM D 3574-95 Test D; or 5 to 65 lb / ft 3 (80 to 1,041 kg / m 3 )、or 6 to 20 lb / ft 3 (96 to 320 kg / m 3 )、or 8 to 15 lb / ft 3 (128 to 240 kg / m 3 ) can have a density of.

[0056] In an embodiment, the composite thermal management sheet is used as a single layer. However, multiple single layers can be stacked and used as a single layer. Other layers can be used in combination with the composite thermal management sheet, for example, a flame retardant layer, a non-porous elastomeric barrier layer, an adhesive layer, etc. or combinations thereof. However, one advantage of the composite thermal management sheet is that a single sheet used alone can be effective without other layers even at a thickness as thin as 1 to 30 mm, or 1 to 20 mm, or 1 to 15 mm, or 1 to 10 mm, or 1 to 8 mm, or 1 to 6 mm.

[0057] When used, the flame retardant layer may include flame-retardant inorganic materials such as boehmite, aluminum hydroxide, or magnesium hydroxide, an expandable material, or a combination thereof. The expandable material may include an acid source, a blowing agent, and a carbon source. Each component may exist in a separate layer or as a mixture, preferably a dense mixture. For example, the expandable material may include an acid source, a blowing agent, and a carbon source. For example, when the temperature reaches a value of, for example, 200-280°C, an acidic species (e.g., a polyphosphoric acid) can react with a carbon source (e.g., pentaerythritol) to form char. When the temperature rises to, for example, 280-350°C, the blowing agent can then decompose to give a gaseous product that swells the char.

[0058] The acid source may include, for example, organic or inorganic phosphorus compounds, organic or inorganic sulfates (e.g., ammonium sulfate), or combinations thereof. Organic or inorganic phosphorus compounds may include organophosphates or organophosphonates (e.g., tris(2,3-dibromopropyl)phosphate, tris(2-chloroethyl)phosphate, tris(2,3-dichloropropyl)phosphate, tris(l-chloro-3-bromoisopropyl)phosphate, bis(1-chloro-3-bromoisopropyl)-1-chloro-3-bromoisopropylphosphonate, polyaminotriazine phosphate, melamine phosphate, triphenyl phosphate, or guanylurea phosphate); organic phosphite esters (e.g., trimethyl phosphite, or triphenyl phosphite); phosphazenes (e.g., hexaphenoxycyclotriphosphazene); phosphorus-containing inorganic compounds (e.g., phosphoric acid, phosphite, phosphite, urea phosphate, ammonium phosphate (e.g., ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, or ammonium polyphosphate)); or combinations thereof.

[0059] The foaming agent may include reagents that decompose at temperatures equal to or above 120°C, for example, 120-200°C or 130-200°C (into smaller compounds such as ammonia or carbon dioxide). The foaming agent may include dicyandiamide, azodicarbonamide, melamine, guanidine, glycine, urea (e.g., urea-formaldehyde resin or methylolated guanylurea phosphate), halogenated organic materials (e.g., chlorinated paraffin), or combinations thereof.

[0060] Expandable materials may include a carbon source. A silicone foam layer can function as a carbon source. The carbon source may include dextrin (phenol-formaldehyde resin), pentaerythritol (e.g., their dimers or trimers), clay, polymers (e.g., polyamide 6, amino-poly(imidazoline-amide), or polyurethane), or combinations thereof. Amino-poly(imidazoline-amide) may include repeating amide linking groups and imidazoline groups.

[0061] The expandable material may optionally further contain a binder. The binder may include epoxy, polysulfide, polysiloxane, polysilarylene, or a combination thereof. The binder may be present in the expandable material in an amount equal to or less than 50 wt%, or 5 to 50 wt%, or 35 to 45 wt%, relative to the total mass of the expandable material. The binder may be present in the expandable material in an amount of 5 to 95 wt%, or 40 to 60 wt%, relative to the total mass of the expandable material.

[0062] Expandable materials may optionally contain synergistic compounds to further improve their flame retardancy. Synergistic compounds may include boron compounds (e.g., zinc borate, boron phosphate, or boron oxide), silicon compounds, aluminosilicates, metal oxides (e.g., magnesium oxide, iron oxide, or aluminum oxide hydrate (boehmite)), metal salts (e.g., alkali metal salts or alkaline earth metal salts or alkaline earth metal carbonate salts of organic sulfonic acids), or combinations thereof. Preferred synergistic combinations include phosphorus-containing compounds comprising at least one of the aforementioned.

[0063] The flame retardant layer may further contain char-forming agents, preferably lignin, boehmite, clay nanocomposites, expandable graphite, pentaerythritol, cellulose, nanosilica, ammonium polyphosphate, lignosulfonate, melamine, cyanurate, zinc borate, hantite, dolomitic or a combination thereof. Although not bound by theory, it is thought that, like expandable materials, char-forming agents can reduce flame spread by using two energy absorption mechanisms, including forming char and then swelling the char.

[0064] The flame retardant layer may further contain polymer binders, such as silicone, polyurethane, ethylene-vinyl acetate, ethylene-methyl acrylate, ethylene-butyl acrylate, or combinations thereof. The flame retardant layer may have a thickness of 0.1 to 2 mm, 0.5 to 1.5 mm, or 0.8 to 1.1 mm.

[0065] When used, the non-porous elastomer barrier layer is measured at 25°C and 1 atm, respectively, with a density of 20 g-mm / m². 2 Less than a day, or 10g-mm / m 2 Less than a day, or 5g-mm / m 2The material comprises an elastomer having a water permeability coefficient of less than 1 day; or a tensile stress of 0.5 to 15 megapascals at 100% elongation measured at 21°C according to ASTM 412; or a combination thereof. The non-porous elastomer barrier layer may have a thickness of 0.25 to 1 mm or 0.4 to 0.8 mm.

[0066] A non-porous elastomer barrier layer may include an elastomer material that is hydrophobic to prevent water or water vapor permeation. For example, the elastomer barrier layer may include a thermoplastic elastomer (TPE), provided that it has preferred hydrophobicity (lack of water or water vapor permeation). Classes of TPE include styrene block copolymers (TPS or TPE-s), (TPO or TPE-o), thermoplastic vulcanized products (TPV or TPE-v), thermoplastic polyurethanes, thermoplastic copolyesters (TPC or TPE-E), thermoplastic polyamides (TPA or TPE-A), and others.

[0067] Specific examples of elastomer materials that can be used include acrylic rubber, butyl rubber, halogenated butyl rubber, copolyester, epichlorohydrin rubber, ethylene-acrylic rubber, ethylene-butylacrylic rubber, ethylene-propylene rubber, and other ethylene-diene rubbers (EPR), ethylene-propylene-diene monomer rubber (EPDM), ethylene-vinyl acetate, fluororubber, perfluoroelastomer, polyamide, polybutadiene, polychloroprene, polyolefin rubber, polyisoprene, polysulfide rubber, natural rubber, nitrile rubber, low-density polyethylene, polypropylene, thermoplastic polyurethane elastomer (TPU), silicone rubber, fluorinated silicone rubber, styrene-butadiene, styrene-isoprene, vinyl rubber, or combinations thereof. In one embodiment, the non-porous elastomer barrier layer includes ethylene-propylene-diene monomer rubber, polychloroprene, or combinations thereof.

[0068] Adhesive layers may be present to bond the composite thermal management sheet to another composite thermal management sheet, another type of layer, or a cell array or battery component. A wide variety of adhesives known in the industry can be used on the composite thermal management sheet. The adhesive can be selected for ease of application to the battery and stability under operating conditions. Each adhesive layer may be the same or different, and may be the same or different thickness. Suitable adhesives include phenolic resins, epoxy adhesives, polyester adhesives, polyvinyl fluoride adhesives, acrylic or methacrylic adhesives, or silicone adhesives, preferably acrylic or silicone adhesives. In some embodiments, the adhesive is a silicone adhesive. Solvent-cast, hot-melt two-component adhesives can be used. Each adhesive layer may independently have a thickness of 0.00025 to 0.010 inches (0.006 to 0.25 mm) or 0.0005 to 0.003 inches (0.01 to 0.08 mm).

[0069] If the composite thermal control sheet includes an adhesive layer, the composite thermal control sheet may further include a release layer. "Release layer" means any single or composite layer including a release coating supported on one or more additional layers, which may include a release liner. The thickness of each release layer may be 5 to 150 micrometers (μm), 10 to 125 μm, 20 to 100 μm, 40 to 85 μm, or 50 to 75 μm.

[0070] A composite thermal management sheet is placed in an electrochemical cell to provide a cell assembly for a battery. The cell may be a lithium-ion battery, particularly a prism cell, a cylindrical cell, or a pouch cell. Figure 2 illustrates an embodiment of the position of the composite thermal management sheet in a cell assembly 1002, and Figure 3 illustrates another embodiment of the position of the composite thermal management sheet in a cell assembly 1003. Figures 2 and 3 illustrate that the composite thermal management sheet 10 can be positioned between a first cell 103 and a second cell 104. Figure 2 illustrates that the composite thermal management sheet 10 may be approximately the same size as the height and width of cells 103 and 104. Figure 3 illustrates that the composite thermal management sheet 10 may be smaller than each of the cells 103 and 104. Also, as shown in Figure 3, the composite thermal management sheet 10 may extend beyond the edges of the electrochemical cells 103 and 104. A composite thermal management sheet extending beyond the edges of the electrochemical cells may wrap around or cover at least another portion or all of another surface of the cell.

[0071] Figure 4 illustrates that a multi-cell assembly 1004 may contain more than two cells 103 and 104, with the composite thermal management sheet 10 positioned between each of the cells 103 and 104. The cells may be lithium-ion batteries, particularly pouch cells. Figure 4 illustrates that a battery assembly 1004 may contain more than two cells (e.g., 103 and 104), with the composite thermal management sheet 10 positioned between each of the cells 103 and 104 and each of the other cells. In some embodiments, 2 to 10 composite thermal management sheets may be positioned on the cells or in the cell array during the fabrication of the battery assembly 1004. For example, 2 to 10 composite thermal management sheets may be positioned internally, for example facing the electrodes, or externally, facing the outside of the battery. 2 to 10 fire-resistant composite thermal management sheets may be positioned on or bonded to the cells, the pouches of the pouch cells, or both. Naturally, depending on the number of cells and cell arrays, there may be more than 10 composite thermal management sheets. Figure 4 further illustrates a composite thermal management sheet 10a positioned on the outside of the battery assembly 1004 so as to face the outside of the battery.

[0072] In one embodiment, at least a portion of the exposed outer edge of the composite thermal management sheet may include a material 88 that draws heat away from the body of the composite thermal management sheet. Exemplary materials applied to the exposed edge of the composite thermal management sheet include ceramics such as boron nitride or aluminum nitride, metals such as aluminum, high heat capacity waxes, phase change materials, or combinations thereof.

[0073] Cell assemblies are used in batteries. A battery includes a housing that at least partially encloses one or more electrochemical cells or cell arrays. The housing can be of any type, for example, polymer or pouch of pouch cells. A composite thermal management sheet can be placed on or directly on the cells or cell arrays in any structure of the battery. The composite thermal management sheet can be placed between individual cells or cell arrays of the battery. The composite thermal management sheet can be placed on the side of the cells or cell arrays, for example, above, in the middle, below, adjacent to, or in combination with them, in the battery, in part thereof, or in a selected set of cells or cell arrays of the battery. The composite thermal management sheet can be placed on or bonded to several of the pouch cells, pressure management pads, cooling plates, or other internal battery components. The assembly pressure of the battery can hold the stacked components in place.

[0074] For example, as shown in Figure 5, the battery 2001 may contain multiple cells in multiple cell arrays 700 inside the housing 800. The composite thermal management sheet 10 can be placed between two cell arrays 700. Furthermore, as shown in Figure 12, the composite thermal management sheet 10 can be placed along multiple cells of the cell array between the side of the housing 800 and the side of the cell array 700. Also, as shown in Figure 12, the thermal insulation composite thermal management sheet 10 can be placed between the end of the housing 800 and the end of one or more cell arrays 700.

[0075] When two or more composite thermal management sheets or other layers are used, the sheets and layers can be assembled by methods known in the art. The sheets and layers can be assembled onto the surface of a cell or other component of a battery (e.g., the wall of a battery case). In some embodiments, the sheets and layers are assembled separately and then installed or bonded to the cell, battery component, or both. Each sheet or layer can be manufactured separately and then laminated (installed, or bonded, for example, using one or more adhesive layers) in a desired order. Alternatively, one or more individual layers can be manufactured into separate individual layers by, for example, coating, casting, or lamination using heat and pressure. In some embodiments, for example, a flame retardant layer or adhesive layer can be directly cast onto a composite thermal management sheet. Direct coating or casting can reduce thickness and improve flame retardancy by eliminating the adhesive layer.

[0076] The following examples are provided to illustrate this disclosure. The examples are illustrative and are not intended to limit the devices manufactured in accordance with the disclosures of materials, conditions or process parameters described herein. [Examples]

[0077] The materials listed in Table 1 were used in the examples.

[0078] [Table 1]

[0079] Sample preparation Samples of Examples 1-6 were prepared by using benzyl alcohol as a foaming agent and preparing a two-component formulation having parts A and B as shown in Table 2. The filler was incorporated into part A. Then, parts A and B were mixed and cast between two release layers. The casting amount was adjusted so that the desired thickness was obtained after foaming and curing of the casting mixture. Foaming and curing were carried out at 70°C for 10 minutes. The composite heat control sheets of Examples 1-6 were cured at 94°C for 12 hours and cut to the appropriate size. The composite heat control sheets were then tested as described below.

[0080] Thermal test The thermal performance of each sample was determined in a thermal runaway simulation. Figure 6 illustrates the equipment 5000 used for the thermal test. The composite thermal control sheet 10 was placed directly on a hot plate 960 set to 550°C. In Comparative Example 1, the pyrogel surface was placed on the hot plate. A 12.7 mm mica plate cell-like material 970 was placed on the top surface of the composite thermal control sheet 10. A thermocouple sensor 980 was inserted into a hole drilled in the mica plate cell-like material 970, and the thermocouple sensor 980 was placed on the top surface of the composite thermal control sheet 10.

[0081] (Comparative Example 1) Comparative examples including an unfilled polyurethane foam layer and a Pyrogel thermal barrier layer were tested. The two layers were bonded together using a multipurpose silicone adhesive.

[0082] (Examples 1-6) Examples 1 to 6 were prepared using the components shown in Table 2. The amounts are shown as parts by mass for each side, where the vinyl-terminated silicone and reactive filler composition together amount to 100 parts by mass. Part B contained only silicone hydride. Parts A and B were mixed in a mass ratio of A:B = 20:1 (20 parts of Part A and 1 part of Part B).

[0083] Regardless of whether the thermal barrier layer was formed in place or whether decomposition of the thermal barrier layer occurred during the test, Table 2 also shows the thickness of each cured sample before the test.

[0084] [Table 2]

[0085] As shown in Figure 7, the reactive filler containing a combination of borax and zinc borate (Examples 1 and 2) resulted in a thermal barrier layer 11 with a deformed (bent) surface. The curved surface is formed despite the downward force exerted by the cell analogue 970 of the test equipment on the sheet. This force is similar to the force that can be exerted by a battery pad. Despite the downward force exerted by the cell analogue 970, the sheet deforms, and the formed thermal barrier layer lifts the cell analogue 970. As a result, the thermal barrier layer efficiently pushes back in the expanding cell, delaying convective heat transfer by creating air pockets. The surface area of ​​the contact points is also reduced, thereby delaying conductive heat transfer as well.

[0086] Figure 8 shows another diagram of the thermal barrier layer formed from the reactive filler compositions containing borax and zinc borate of Examples 1 and 2. The thermal barrier layer is continuous and flexible. This is in stark contrast to barrier layers formed from prior art compositions, which can be discontinuous and inelastic (brittle), such as charcoal.

[0087] Figure 9 shows the temperature rise detected by thermocouples for each sample measured over time. Advantageously, all samples demonstrated thermal barrier properties. Reactive filler compositions containing a combination of borax and zinc borate (Examples 1 and 2) yielded better thermal performance than Examples 3-6.

[0088] Examples 1 and 2 had the same composition, but the thicker sheet of Example 1 provided better thermal protection to the opposite surface than the thinner sheet of Example 2. After 10 minutes, the measured temperature of Example 1 was lower than that of Comparative Examples 1 and Examples 2-6. For electric vehicle battery applications, technical feasibility can be determined by the time it takes to reach 150°C, which is preferably as long as possible, for example, at least 10 minutes. Even after a long exposure of 20 minutes, the opposite surface of the composite thermal management sheet of Example 1 was only 140°C and did not reach 150°C.

[0089] While not constrained by theory, the excellent results obtained in Example 1 are thought to be due to different mechanisms working in cooperation. First, heat is thought to be absorbed due to the heat capacities of borax and zinc borate. Heat is further absorbed by the release of water from the borax. The generation of water vapor can lead to increased thermal convection through the flexible porous layer away from the heat source. However, increased exposure to the heat source forms a thermal barrier layer that prevents thermal convection by water vapor and hot gases, thereby resulting in improved high-temperature heat resistance. The formation of a thermal barrier layer can further reduce or suppress heat conduction. In Examples 1 and 2, which show the formation of a deformed barrier, heat conduction can be additionally reduced.

[0090] Nail-piercing test A nail-piercing test was conducted. Figures 10A and 10B are schematic diagrams of the first equipment 7000 used in the nail-piercing test, one disassembled and the other not disassembled, respectively, and include aluminum end plates 910 and 920 (with dimensions of 185 mm x 90 mm x 15.2 mm), polytetrafluoroethylene insulating films 930 and 940 (with dimensions of 185 mm x 90 mm x 1 mm), pouch cells 201 and 202, and test specimen 950 (e.g., composite thermal control sheet). The characteristics of cells 201 and 202 are shown in Table 3. To initiate thermal runaway, a hole was made in cell 201 with an 8 mm needle inserted at a press-fitting speed of 10 mm / s. Cells 201 and 202 were electrically insulated. Multiple thermocouples measured the temperature profile. Position V1 was between cell 201 (which had a nail stuck in it, e.g., was non-functional) and test sample 950, and position V2 was between test sample 950 and the adjacent cell 202. Voltage was also measured.

[0091] [Table 3]

[0092] (Comparative Example 2) A comparative example without a foam layer was tested.

[0093] (Comparative Example 3) A comparative example containing an unfilled polyurethane foam layer was tested.

[0094] (Examples 7 and 8) Examples 7 and 8 were prepared using the components shown in Table 4. Parts A and B were mixed in a mass ratio of A:B = 20:1 (20 parts of Part A and 1 part of Part B).

[0095] [Table 4]

[0096] The results of the nail-piercing test for Comparative Example 2 and Example 7 are shown in Table 5 and Table 6, and in Figures 11 and 12. Figure 11 is a graph of temperature (°C) versus time (min) showing the results of the nail-piercing test for Comparative Example 3 and Example 7. As shown in Figure 11, Example 7 was able to stop thermal runaway in the test. Figure 12 is a graph of bolt (V) versus time (min) showing the results of the nail-piercing test for Comparative Examples 2 and 3 and Example 7 with different thicknesses. The results in Figure 12 include a delay of 18 seconds for Comparative Example 12, a delay of 31 seconds for Comparative Example 2, a delay of 102 seconds for Example 7 with a thickness of 2 mm, and no thermal runaway for Example 7 with a thickness of 3 mm.

[0097] [Table 5]

[0098] [Table 6]

[0099] UL94 500W (125mm) Vertical Combustion Test Each of the 20(20) material types was subjected to conditions of 70±2°C and 168±2 hours according to UL94 Section 6.2. All samples were prepared and tested according to UL94 Section 9.5. Table 7 shows the vertical combustion material classification requirements, and Table 8 shows the test results.

[0100] [Table 7]

[0101] [Table 8]

[0102] The results of the microcalorimetry for Comparative Example 3 are shown in Figure 13 and Table 9, the results of the microcalorimetry for Example 7 are shown in Figure 14 and Table 10, and the results of the microcalorimetry for Example 8 are shown in Figure 15 and Table 11. Figures 13, 14, and 15 have different X and Y axis scales.

[0103] [Table 9]

[0104] [Table 10]

[0105] [Table 11]

[0106] Figures 16A and 16B are schematic diagrams of the disassembled and assembled second apparatus 8000 for the nail penetration test, and a non-disassembled schematic diagram, respectively, and include aluminum end plates 911, 921, polytetrafluoroethylene insulating films 931, 941, 12Ah pouch cells 203, 204, 205, and test specimens 951, 952 (e.g., composite thermal control sheets). Cell 204 was punctured with a needle to initiate thermal runaway. Cells 203, 204, and 205 were electrically insulated. Multiple thermocouples measured temperature profiles at positions V3, V4, V5, TC1, TC2, and TC8 as shown in Figure 16A.

[0107] The results of the nail-piercing test for Comparative Example 3 are shown in Table 10 (Table 12) and Figure 17, the results of the nail-piercing test for Example 7 are shown in Table 11 (Table 13) and Figures 18 and 19, and the results of the nail-piercing test for Example 8 are shown in Table 12 (Table 14) and Figure 20. Figures 17, 18, and 20 are graphs of temperature (°C) versus time (seconds (s)). Figure 19 is a photograph of Example 7 after the nail-piercing test, and it is desirable that the flexibility is maintained as shown.

[0108] [Table 12]

[0109] [Table 13]

[0110] [Table 14]

[0111] The following describes some non-limiting aspects of this disclosure.

[0112] Embodiment 1: A composite thermal management sheet for a battery comprising a silicone foam layer and a reactive filler composition disposed within the silicone foam layer, wherein the reactive filler composition comprises a first filler that decomposes upon initial exposure to heat to produce water, and a second filler different from the first filler, wherein the second filler forms a thermal barrier layer with the decomposition products of the first filler, absorbs water, or both.

[0113] Embodiment 2: The composite thermal control sheet according to Embodiment 1, wherein the thermal barrier layer includes a borosilicate glass layer, preferably a borosilicate glass layer having a curved surface.

[0114] Embodiment 3: The composite thermal management sheet according to Embodiment 2, wherein the borosilicate glass contains silicon derived from the decomposition of the silicone foam layer.

[0115] Embodiment 4: A composite thermal management sheet according to any one of Embodiments 1 to 3, wherein the first and second fillers are at least two of the following: aluminum trihydrate, ammonium nitrate, borax, hydrated sodium silicate, magnesium hydroxide, magnesium carbonate hydroxide pentahydrate, trimagnesium phosphate octahydrate, zinc borate, superabsorbent polymer, or water glass.

[0116] Embodiment 5: The composite thermal management sheet according to Embodiment 4, wherein the first filler comprises aluminum trihydrate, hydrated sodium silicate, magnesium carbonate hydroxide pentahydrate, trimagnesium phosphate octahydrate, superabsorbent polymer, water glass, or a combination thereof.

[0117] Embodiment 6: A composite thermal management sheet according to Embodiment 4 or 5, wherein the second filler comprises ammonium nitrate, borax, hydrated sodium silicate, magnesium hydroxide, magnesium carbonate hydroxide pentahydrate, trimagnesium phosphate octahydrate, zinc borate, superabsorbent polymer, or a combination thereof.

[0118] Embodiment 7: The composite thermal management sheet according to Embodiment 4, wherein the reactive filler composition comprises aluminum trihydrate and zinc borate.

[0119] Embodiment 8: The composite thermal management sheet according to Embodiment 4, wherein the reactive filler composition comprises borax and hydrated sodium silicate.

[0120] Embodiment 9: The composite thermal management sheet according to Embodiment 4, wherein the reactive filler composition comprises aluminum trihydrate, zinc borate, and hydrated sodium silicate.

[0121] Embodiment 10: The composite thermal management sheet according to Embodiment 4, wherein the reactive filler composition comprises borax and zinc borate.

[0122] Embodiment 11: The composite thermal management sheet according to Embodiment 4, wherein the reactive filler composition comprises borax, zinc borate, and aluminum trihydrate.

[0123] Embodiment 12: The composite thermal management sheet according to any one of Embodiments 4 to 11, wherein the reactive filler composition further comprises a superabsorbent polymer, water glass, or both.

[0124] Embodiment 13: The composite thermal management sheet according to Embodiment 12, wherein the reactive filler composition comprises aluminum trihydrate, hydrated sodium silicate, magnesium carbonate hydroxide pentahydrate, trimagnesium phosphate octahydrate, or a combination thereof; and a superabsorbent polymer, preferably poly(sodium acrylate).

[0125] Embodiment 14: A composite thermal management sheet according to any one of Embodiments 1 to 13, having a thickness of 1 to 30 mm, 1 to 20 mm, 1 to 15 mm, 1 to 10 mm, 1 to 8 mm, 1.5 to 8 mm, 1.5 to 6 mm, or 2.5 to 6 mm.

[0126] Apparatus 15: Densities of 5–65 pounds / cubic foot (80–1,041 kilograms / cubic meter), or 6–20 pounds / cubic foot (96–320 kilograms / cubic meter), or 8–15 pounds / cubic foot (128–240 kilograms / cubic meter); compressive deflection of 0.2–125 pounds per square inch (1–862 kilopascals), or 0.25–20 pounds per square inch (1.7–138 kilopascals), or 0.5–10 pounds per square inch (3.4–68.90.5 kilopascals), determined with 25% deflection according to ASTM D3574-17; ASTM D A composite thermal control sheet according to any one of embodiments 1 to 14, having a compression set of 0-15%, 0-10%, or 0-5% at 70°C according to Test D 3574-95; or a combination thereof.

[0127] Embodiment 16: A battery assembly comprising a composite thermal management sheet according to any one of Embodiments 1 to 15, disposed on the surface of an electrochemical cell, preferably a lithium-ion electrochemical cell.

[0128] Embodiment 17: The battery assembly according to Embodiment 16, wherein the electrochemical cell includes a prism cell, a pouch cell, or a cylindrical cell.

[0129] Embodiment 18: The battery assembly according to Embodiment 16 or 17, wherein the assembly comprises at least two electrochemical cells.

[0130] Embodiment 19: A battery comprising a battery assembly according to any one of Embodiments 16 to 18, and a housing that at least partially encloses the battery assembly.

[0131] Compositions, methods, and articles may consist of, or essentially consist of, any preferred materials, steps, or components disclosed herein as alternatives. Compositions, methods, and articles may further, or alternatively, be formulated to lack or substantially omit any materials (or types), steps, or components that are not otherwise necessary for achieving the function or purpose of the composition, method, or article.

[0132] The terms "a" and "an" indicate the presence of at least one of the items being referred to, not a limitation of quantity. The term "or" means "and / or" unless the context clearly specifies otherwise. Throughout this specification, references to "aspects," "other aspects," etc., mean that certain elements described in relation to an aspect (e.g., features, structure, steps, or characteristics) may be included in at least one aspect described herein and may or may not be present in other aspects. Furthermore, it should be understood that the elements described may be combined in any suitable manner among the various aspects.

[0133] When an element such as a layer, film, region, or substrate is said to be "in contact" with another element, it may be directly in contact with the other element, or an intervening element may also be present. In contrast, when an element is said to be "directly" in contact with another element, no intervening element is present.

[0134] Unless otherwise specified herein, all test standards are the most current and valid standards as of the filing date of this application, or, if priority is claimed, as of the filing date of the first priority application in which the test standard was made public.

[0135] The endpoints of the entire range covering the same part or property encompass the endpoints, are independently combinable, and include all intermediate points and ranges. For example, the range “up to 25 wt% or 5 to 20 wt%” encompasses the endpoints and all intermediate values ​​of ranges such as “5 to 25 wt%,” for example, 10 to 23 wt%. The terms “first,” “second,” etc., “primary,” “secondary,” etc., when used herein, do not indicate any order, quantity, or importance, but rather are used to distinguish elements from one another. The term “combinations of them” is open-ended, meaning that the list encompasses each element individually, and furthermore, it encompasses combinations of two or more elements in the list, and combinations of at least one element in the list with unnamed similar elements. The term “combination” also includes blends, mixtures, alloys, reaction products, etc.

[0136] Unless otherwise defined, scientific and technical terms used herein have the same meanings as those commonly understood by those skilled in the art in which this disclosure pertains.

[0137] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, in the event of any inconsistency or conflict between terms in this application and terms in any of the incorporated references, the terms from this application shall prevail over the conflicting terms from the incorporated references.

[0138] In the drawings, the width and thickness of layers and regions may be exaggerated for clarity and ease of explanation of the specification. Similar reference numerals in the drawings refer to similar elements.

[0139] Exemplary embodiments are described herein with reference to schematic cross-sectional views of idealized embodiments. Therefore, variations from the illustrated shapes should be expected, for example, as a result of manufacturing techniques and / or tolerances. Accordingly, embodiments described herein should not be construed as being limited to specific shapes of regions as illustrated herein, and include, for example, deviations in shape due to manufacturing. For example, regions illustrated or described as flat may typically have rough and / or nonlinear features. Furthermore, illustrated acute angles may also be rounded. Accordingly, regions shown in the figures are essentially schematic, and their shapes are not intended to illustrate the exact shapes of regions and are not intended to limit the scope of these claims.

[0140] While specific embodiments are described, alternative methods, modifications, variations, improvements, and substantial equivalents may arise that are not currently foreseeable or foreseeable. Therefore, the attached claims, which are filed and may be modified, are intended to encompass all such alternative methods, modifications, variations, improvements, and substantial equivalents. [Explanation of symbols]

[0141] 10. Combined Thermal Management Sheet 10a Composite Thermal Management Sheet 11. Thermal barrier layer 12 Flexible silicone foam layer 14 First outer surface 16. Second outer surface 18 pores 20 Internal surface 22 Filler 24 Filler 88 Material 103 First cell 104 Second cell 201 Pouch Cell 202 Pouch Cells 203 Pouch Cell 204 Pouch Cells 205 Pouch Cells 910 Aluminum end plate 911 Aluminum end plate 920 aluminum end plate 921 Aluminum end plate 930 Insulating film 931 Insulating film 940 Insulating Film 941 Insulating film 950 test samples 951 Test sample 952 Test Samples 960 Hot Plate 970 Mica plate cell analog 980 Thermocouple Sensor 1002 Assembly 1003 Assembly 1004 Assembly 2001 Battery 5000 equipment 7000 First Equipment 8000 Second facility

Claims

1. A composite thermal management sheet for batteries, A single layer of silicone foam, The reactive filler composition comprises a reactive filler composition disposed within the silicone foam layer, and the reactive filler composition is A first filler that decomposes upon initial exposure to heat to produce water, The material comprises a second filler different from the first filler, wherein the second filler forms a thermal barrier layer with decomposition products of the first filler, absorbs the water, or both. The composite thermal management sheet has a single-layer structure and does not include any other layer on the single-layer silicone foam layer, and is a composite thermal management sheet for batteries.

2. The composite thermal management sheet according to claim 1, wherein the thermal barrier layer includes a borosilicate glass layer.

3. The composite thermal management sheet according to claim 2, wherein the borosilicate glass contains silicon derived from the decomposition of the silicone foam layer.

4. The composite thermal management sheet according to any one of claims 1 to 3, wherein the first filler and the second filler are at least two of the following: aluminum trihydrate, ammonium nitrate, borax, hydrated sodium silicate, magnesium hydroxide, magnesium carbonate hydroxide pentahydrate, trimagnesium phosphate octahydrate, zinc borate, superabsorbent polymer, or water glass.

5. The composite thermal management sheet according to claim 4, wherein the first filler comprises aluminum trihydrate, hydrated sodium silicate, magnesium carbonate hydroxide pentahydrate, trimagnesium phosphate octahydrate, superabsorbent polymer, water glass, or a combination thereof.

6. The composite thermal management sheet according to claim 4 or 5, wherein the second filler comprises ammonium nitrate, borax, hydrated sodium silicate, magnesium hydroxide, magnesium carbonate hydroxide pentahydrate, trimagnesium phosphate octahydrate, zinc borate, superabsorbent polymer, or a combination thereof.

7. The composite thermal management sheet according to claim 4, wherein the reactive filler composition comprises aluminum trihydrate and zinc borate.

8. The composite thermal management sheet according to claim 4, wherein the reactive filler composition comprises borax and hydrated sodium silicate.

9. The composite thermal management sheet according to claim 4, wherein the reactive filler composition comprises aluminum trihydrate, zinc borate, and hydrated sodium silicate.

10. The composite thermal management sheet according to claim 4, wherein the reactive filler composition comprises borax and zinc borate.

11. The composite thermal management sheet according to claim 4, wherein the reactive filler composition comprises borax, zinc borate, and aluminum trihydrate.

12. The composite thermal management sheet according to any one of claims 4 to 11, wherein the reactive filler composition further comprises a superabsorbent polymer, water glass, or both.

13. The reactive filler composition Aluminum trihydrate, hydrated sodium silicate, magnesium carbonate hydroxide pentahydrate, trimagnesium phosphate octahydrate, or combinations thereof; and A composite thermal management sheet according to claim 12, comprising a superabsorbent polymer.

14. A composite thermal management sheet according to any one of claims 1 to 13, having a thickness of 1 to 30 millimeters.

15. Density of 5 to 65 pounds per cubic foot (80 to 1,041 kilograms per cubic meter); Compressive deflection of 0.2 to 125 pounds per square inch (1 to 862 kilopascals), determined according to ASTM D3574-17 with a 25% deflection; Settling set of 0-15% compression set at 70°C according to ASTM D 3574-95 Test D; or A composite thermal management sheet according to any one of claims 1 to 14, having a combination thereof.

16. A battery assembly comprising a composite thermal management sheet according to any one of claims 1 to 15, disposed on the surface of an electrochemical cell.

17. The battery assembly according to claim 16, wherein the electrochemical cell includes a prism cell, a pouch cell, or a cylindrical cell.

18. The battery assembly according to claim 16 or 17, wherein the assembly comprises at least two electrochemical cells.

19. Battery assembly according to any one of claims 16 to 18; and A battery, including a housing that at least partially encloses the aforementioned battery assembly.

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