Thermal runaway barrier textile composite

Abstract

A thermal runaway barrier system utilizes a thermal runaway barrier having alternating layers of a woven fabric including high temperature yarns and an elastomer layer, wherein the thermal runaway barrier is thin and flexible to conform to contours of a complex three dimensional enclosure, and has a blast resistance of at least four cycles according to test method UL2596 Torch and Grit (TaG) method, a dielectric strength per unit thickness as defined by a breakdown voltage of at least 12kV / mm, and maintains at least 3.1 kV / mm after a thermal runaway event.

Description

THERMAL RUNAWAY BARRIER TEXTILE COMPOSITECross Reference To Related Applications

[0001] This application claims the benefit of priority to U.S. provisional patent application No. 63 / 674,577, filed on July 23, 2024; the entirety of which is hereby incorporated by reference herein.BACKGROUND OF THE INVENTIONField of the Invention

[0002] The invention relates a thermal runaway barrier system comprising a thermal runaway barrier comprising alternating layers of a woven fabric having high temperature yarns and an elastomer layer, wherein the thermal runaway barrier is thin and flexible to conform to contours of a complex three dimensional enclosure, and has a blast resistance of at least four cycles according to the Torch and Grit (TaG) test method within UL2596 Test Method for Thermal and Mechanical Performance of Battery Enclosure Materials, a dielectric strength per unit thickness as defined by a breakdown voltage of at least 12 kV / mm, and maintains at least 3.1 kV / mm after a thermal runaway event.Background

[0003] Effective thermal management is a necessary element of energy storage systems, especially with respect to electric vehicle batteries. Thermal runaway barriers are often used for the prevention, containment and anti-propagation of thermal runaway, a potential phenomenon in which a lithium ion battery cell fails, and uncontrollable self-heating occurs, setting off a chain reaction with adjacent cells, exponential increase in temperature, and combustion. Thermal runaway barriers prevent setting fire to or damaging surrounding components or items. A covered item may be a battery that is configured in an electronic device, wherein reducing weight is an important benefit, such as a portable electronic device. Thermal runaway barriers prevent heat, fire and explosions of a covered item from causing damage to surrounding items and material. Therefore, thermal runaway barriers are required to be thermally stable to a high temperature and durable whereby they maintain structure integrity and dielectric strength after an explosive event.SUMMARY OF THE INVENTION

[0004] The invention is directed to a thermal runaway barrier system comprising a thermal runaway barrier comprising alternating layers of a woven fabric and an elastomer layer, wherein an exemplary thermal runaway barrier is no more than 3 mm thick, no more than 3.4 kg / m2, is conformable to conform to contours of a complex three dimensional (3D) enclosure and has a blast resistance of at least four cycles according to the Torch and Grit (TaG) test method within UL2596, a dielectric strength per unit thickness as defined by a breakdown voltage of at least 12 kV / mm, and maintains at least 3.1 kV / mm after a thermal runaway event.

[0005] An exemplary thermal runaway barrier is a thin sheet of material that is supple or conformable for conforming to a covered item. Conforming to the contours of a covered item, reduced the volume of space required for the covered item and may help improved barrier performance. Gaps or space between the thermal runaway barrier and the covered item may enable projectiles from an explosive event to cause more damage to the thermal runaway barrier. A thermal runaway barrier may be conformable, as defined herein, and have a nominal bending moment of less than 0.10 N-m measured via ASTM D747 cantilever method. In solid mechanics, bending moment is measured by applying a force at a given distance away from a point of reference, causing a bending effect. This property allows for high conformability to battery enclosures and other complex 3D structures requiring thermal runaway protection. An exemplary thermal runaway barrier has a heat of combustion of at least 25 MJ / kg according to ASTM E1354. The ASTM E1354 standard for the cone calorimeter determines a response of materials exposed to controlled levels of radiant heating with or without an ignition source. The cone measures intensity of the peak rate of heat release (PRHR) and the speed to reach PRHR.

[0006] An exemplary thermal runaway barrier is a thin sheet of material that is conformable for conforming to contours or around features of a covered item. Conforming to the contours of a covered item, reduced the volume of space required for the covered item and may help improved barrier performance. Gaps or space between the thermal runaway barrier and the covered item may enable projectiles from an explosive event to cause more damage to the thermal runaway barrier. A thermal runaway barrier may have a nominal bending moment of less than 0.10 N-m measured via ASTM D747 cantilever method. In solid mechanics, bending moment is measured by applying a force at a given distance away from a point of reference, causing a bending effect. This property allows for high conformability to battery enclosures and other complex 3D structures requiring thermal runaway protection.

[0007] A thermal runaway barrier includes alternating layers of a woven fabric and an elastomer layer. The thermal runaway barrier may have two layers of each of the wovenfabric and elastomer layer. The thermal runaway barrier may have a number of layers depending on the application and may have four or more layers, ten or more layers, 20 or more layers, 30 or more layers, 40 or more layers, and even 50 or more layers and any range between and including the number of layers provided. The woven fabric includes or consists essentially of or consists of high temperature yarns that are thermally stable to about 650°C or more, about 800°C or more, about 1 ,000°C or more, about 1400°C or more. In a battery thermal runaway event the temperatures may exceed 1,000oC or more, so a fabric layer with high temperature yarns that support textile composite thermal stability are preferred for these applications.

[0008] An elastomer layer includes an elastomer including, but not limited to, silicone, polychloroprene, polyurethane, melamine-formaldehyde, fluorosilicone, fluoroelastomers, and the like. A preferred elastomer will form a char layer when combusted and may oxidize when thermally degraded. Silicone may be preferred as the elastomer in the elastomer layer as it has relatively high temperature stability and also effectively forms a char layer by oxidizing to form silicon oxides. Also, silicone is cost effective for these applications and produces less toxic gases when combusted. The silicone may be a high molecular weight silicone having a molecular weight of 200,000 g / mol or more. An elastomer, such as a silicone elastomer, may also include fillers or other materials to increase durability and heat resistance of the elastomer, such as iron oxide, which gives some silicone elastomer a red color.

[0009] An elastomer layer may include fillers that further redirect heat flux from passing normally through the elastomer layer and thermal runaway barrier. The fillers may be inorganic fillers including, but not limited to, phlogopite mica, boron nitride, graphite and graphene. The fillers may be platelet fillers having a planar shape and high aspect ratio with a length and width that is three times or more a thickness of the platelet filler and preferably 5 times or more, or even 10 times or more. The platelet fillers may create an aggregated tortuous path layer normal to a thickness of the thermal runaway barrier and an impinging flame (heat) or grit front. The platelet fillers may increase abrasion resistance by providing a hard scale type layer of inorganic materials. Also, an elastomer layer with a platelet filler may improve thermal protection by acting as a thermal spreader in the plane of the elastomer layer or thermal runaway barrier layer, or in an x-y plane. A platelet filler may enhance the low thermal conductivity of the elastomer, such as an oxidized silicone and may further reduce normal heat flux through the thermal runaway barrier and increases the temperature differential across the thickness of the thermal runaway barrier, by conducting and directing thermal energy laterally in the thermal runaway barrier. A silicone will become oxidized silicone or silicon-dioxide during a thermal runaway event.

[0010] Additionally, the addition of platelet filler in one or more of the elastomer layers can be modified to enhance radiative cooling via selective emissivity, wherein the platelet filler emits longer wavelength infrared energy more rapidly than the shorter wavelength energy impinged on the composite by the flame front. This emissivity function of the platelet filler enables rechanneling of heat flux away from the flame impinged surface and increases thermal runaway barrier temperature differential through radiative cooling.

[0011] The amount of filler, including a platelet filler, included in an elastomer layer by weight of the elastomer layer, may be about 10% or more, about 20% or more, about 40% or more, about 50% or more, or even about 75% or more. A filler concentration in an elastomer layer of at least 20% or more or 40% or more, such as from about 20% to about 60% may be preferred when using platelet filler to produce a tortuous path through the elastomer layer around the platelet fillers, or to provide full surface coverage of platelet fillers, wherein platelet fillers substantially (90% of the area of more) extend in-plane within the elastomer layer.WOVEN FABRIC LAYER

[0012] A woven fabric includes high temperature yarns that may be woven in a satin weave, as this weave type produces a more conformable fabric than a plain or twill weave. An exemplary weave is a 4-harness satin weave (also called crowfoot satin), having a weft yarn that passes over three warp yarns and under one. This allows for more pliability and elasticity than a plain weave and may aid in allowing a thermal runaway barrier to conform to a covered item. Also, a satin weave pattern accommodates a uniform coating layer of elastomer, such as silicone, that adheres extremely well with minimal strikethrough (<10%) (measured via cross sectional scope analysis) compared to a plain weave equivalent, which allows each elastomer and textile layer to function independently. A satin weave allows for a more open structure compared to plain weave. A satin weave has a lower density, less material packed tightly together, resulting in a lower profile (thickness) while maintaining structural integrity. An exemplary satin weave may be 4-harness, 5-harness, 8-harness, or 12-harness satin weave pattern.

[0013] An exemplary woven fabric includes high temperature yarn and may include a composition of different yarn types. An exemplary yarn composition may contain up to 75% silicon dioxide (SiCh) by weight, which contributes to a higher melting point and thus better resistance to thermal degradation when exposed to temperatures up to 1400°C as observed in a lithium battery thermal runaway events. A yarn may have components and / or a composition as detailed in Table 1 . Each of the three yarn types described in Table 1 , have a substantial portion of silicon dioxide, wherein the composition comprises 50% or more, silicone dioxide, such as 60% or more, 70% or more 80% or more and may consistessentially of silicone dioxide having 90% or more silicone dioxide. Type EG yarn includes, silicone dioxide, aluminum(lll) oxide, calcium oxide, diboron trioxide, magnesium oxide, sodium oxide, and potassium oxide (potassium superoxide). Yarn type ECR includes silicone dioxide, aluminum (III) oxide, calcium oxide, magnesium oxide, sodium oxide, potassium oxide (potassium superoxide), iron (III) oxide (ferric oxide), and titanium dioxide. Yarn type HR includes silicone dioxide, aluminum (III) oxide, calcium oxide, magnesium oxide, iron (III) oxide (ferric oxide), titanium dioxide. Yarn type Silica consists primarily of silicone dioxide, having more than 90% by weight silicon dioxide.Table 1 : Yarn Composition By Weight

[0014] An exemplary woven fabric may contain aluminum oxide (AI2O3) in a concentration of about 10% or more, about 15% or more, about 20% or more, and any range between and including the concentrations provided. This substantial concentration of aluminum oxide provides high mechanical strength at elevated temperatures and resistance to thermal shock.

[0015] An exemplary woven fabric may contain calcium oxide (CaO) in a concentration of about 10% or more, about 15% or more, about 20% or more, about 25% or more and any range between and including the concentrations provided. This substantial concentration of calcium oxide provides higher durability, reduced thermal expansion, and electrical insulation properties.

[0016] The woven fabric in the thermal runaway barrier aids in dampening and deceleration of high-energy impact forces during a thermal runaway event. Each individual layer of woven fabric in a thermal runaway barrier material adsorbs impact energy and allows the composite to maintain structural integrity and protect surrounding components and material from exposure to flame and molten particulate. The yarn composition blend is designed foreffective fire safety functionality, which is further enhanced by the use of additional layers in this composite design.

[0017] An exemplary woven fabric may incorporate warp and fill yarns (weft yarns) that are the same composition, or different in composition. For example, the warp yarns may be EG yarns as described in Table 1 , and the weft yarns may be HR or Silica yarns as described in

[0018] An exemplary woven fabric uses a blend of continuous filament fibers with filament diameter ranging from 3 micron to 8 micron, allowing for a balance of high strength (more efficient load bearing with finer filaments packed densely) as well as elasticity and abrasion resistance as a composite structure.

[0019] A woven fabric and / or the yarn of a woven fabric may be thermally stable, as used herein, to a temperature of 400°C or more as defined by residual tensile strength per ASTM D5034 after one hour of continuous exposure at respective temperatures, as shown in Table 2.Table 2: Yarn Thermal Stability (ASTM D5034)ELASTOMER LAYER

[0020] An exemplary thermal runaway barrier includes a layer of elastomer, such as silicone elastomer, which may be applied as a coating onto a woven fabric layer and / or configured between woven fabric layers. Some exemplary elastomer layer formulations are described in Table 3.Table 3: Elastomer Layer Composition

[0021] With reference to TABLE 3, an exemplary silicone elastomer may contain a polysiloxane such as a high vinyl (0,1 % to 0.4% molar fraction) polysiloxane elastomer backbone dispersed with miscible functional filler particles. The polysiloxane elastomer backbone provides high tensile strength, elongation, and high thermoelasticity to maximize strength and impact damping in application. The coating formulation may contain encapsulated aerogel particles which further boost insulative properties, increase flexibility and strength, and reduce weight. The coating formulation may contain a combination of gas-phase and condensed-phase flame retardants which act synergistically as a coating but function via different mechanisms. The aluminum hydroxide and magnesium hydroxide synergistically decompose to form water vapor to quench the flame. An elastomer layer may contain zinc phosphate complex that retards further oxidation in both the gas and condensed phase. An elastomer layer may contain organophosphorus and oxide catalysis. This combination allows the reinforcing elements and silicone itself to remain intact and effectively insulate and protect the battery enclosure from rupture.

[0022] An elastomer layer may contain functional filler particles that are miscible with elastomer for ease of dispersion. Filler particles that may be included in the elastomer layer include, but are not limited to, iron oxide, and any combination thereof. In application the thermal runaway barrier may be exposed to a high-pressure flame front at temperatures up to 1400°C as a result of rapid combustion of lithium-ion battery cells and surrounding components within the pack. A battery pack with 64 kWh energy capacity can release about 9.0 GJ of energy during a thermal runaway event (as the Li B materials decompose, oxygen is released and contributes exponentially to combustion. When the interior elastomer layer is exposed to the flame front, it oxidizes, releases water vapor and flame poisoning chemistry. As an example, a silicone may become silicon-dioxide which has high thermal barrier and stability properties. The elastomer layer combined with the woven fabric is designed to maintain high flexibility and elasticity to effectively absorb and disperse impact energy from high power flame plasma, and particulate release.

[0023] An elastomer layer may include a flame retardant such as aluminum hydroxide or magnesium hydroxide that decomposes to form water vapor to quench the flame. An elastomer layer may include a zinc phosphate complex that retards further oxidation in both the gas and condensed phase. An exemplary elastomer layer may include a flamepoisoning material, such as an organophosphorus, that demonstrates highly effective flame poisoning and oxide catalysis. This combination of filler particles, flame retardant and flame poisoning material allow the reinforcing elements and silicone itself to remain intact and effectively insulate and protect the battery enclosure from rupture.

[0024] The elastomer layer may contain aerogel particles, or encapsulated aerogel particles which further boost insulative properties, increase mechanical strength, and reduce weight. COMPOSITE:

[0025] An exemplary thermal runaway barrier may include at least one layer of woven fabric and one layer of elastomer and for most applications contains two or more layers of woven fabric and two or more layers of elastomer. An exemplary thermal runaway barrier may include between two and 50 layers, or between two and 40 layers, or between two and thirty layers, or between two and twenty layers, or between two and ten layers, or between two and five alternating layers of elastomer and woven fabric. The elastomer may be configured on an inside or interior surface of the thermal runaway barrier. This multilayer composite structure can be supplied with the coating layers in a cured or uncured state, depending on the attachment method and architecture of the covered item, such as a battery enclosure. The elastomer coating layers allow for three-dimensional forming to the battery pack enclosure, such as a lid or battery case, in a manner that keeps the thermal barrier layer as thin as possible and allows air space for proper venting within the battery assembly.

[0026] The alternating layers of an exemplary thermal runaway barrier are designed to maintain high flexibility and elasticity to effectively absorb impact from high power flame plasma, and particulate release. The elastomer layer composition as described herein enables effective char formation in a continuous sheet, in contrast to weaker silicone formulations which fracture and break apart at this stage. Furthermore, the woven fabric layer reinforcement provides mechanical integrity and elongation to provide a tough and insulative matrix when it expands. The elastomer layer may subsequently entrap air to increase the thermal insulation resistance. The elastomer coating layers function in synergy with the woven fabric layers to allow for three-dimensional forming to the battery enclosure lid or battery case, in a manner that keeps the thermal barrier layer as thin as possible and allows air space for proper venting within the battery assembly.

[0027] When the first sacrificial layer of elastomer eventually cracks and cleaves from multiple rounds of high impact molten particulate blast, the subsequent exposed layers of fabric and coating then act as the protective barrier allowing the backside layers of elastomer and fabric to effectively insulate and absorb impact.

[0028] In application, the thermal runaway barrier may be exposed to a high-pressure flame front at temperatures up to 1400°C as a result of rapid combustion of lithium-ion battery cells and surrounding components within the battery pack. A battery pack with 64 kWh energycapacity can release about 9.0 GJ of energy during a thermal runaway event (as the lithium ion battery materials decompose, they release oxygen and contribute exponentially to combustion. When the first sacrificial coating layer of elastomer is exposed to the flame front from a thermal runaway event, it oxidizes absorbing thermal energy.

[0029] An exemplary thermal runaway barrier may be configured around a battery of an electric vehicle. Effective thermal management of electric vehicle battery systems requires anti-propagation of a thermal runaway (TR) event. A thermal runaway event of an electric vehicle battery is a phenomenon in which a battery cell, such as a lithium-ion battery cell, fails and uncontrollable self-heating occurs, setting off a chain reaction with adjacent cells, and exponential increase in temperature, and ultimately concludes combustion.

[0030] An exemplary thermal runaway barrier provides a thermal runaway solution for battery packs that can contain a lithium ion battery fire, which burns much more rapidly than an internal combustion engine vehicle fire. An effective thermal runaway barrier can contain a thermal runaway event of an electric vehicle long enough for passengers to exit the vehicle safely, or within 5 minutes. A thermal runaway event of a battery enclosures may be exposed to temperatures up to 1400°C. The energy released during a thermal runaway event of a battery, such as a lithium ion battery, may be about 8.5 to about 9.0 GJ (2500 kWh) and the average heat of combustion may be about 25MJ / kg or more, about 30 MJ / kg or more, about 35 MJ / kg or more or any range between and including the values provided. A thermal runaway barrier effectively contains and stops propagation of this type of thermal runaway event.

[0031] An exemplary thermal runaway barrier is light weight and thin, as described in Table 4, thereby reducing weight and volume in combination with the covered item. An exemplary thermal runaway barrier is a sheet of material having an interior and exterior surface that extend in parallel planes and has a thickness of about 5.0mm or less, about 4.0mm or less, about 3.0mm or less, about 2.5mm or less, about 2.0mm or less and range between and including the thickness values provide. An exemplary thermal runaway barrier is lightweight, having a weight per unit area of about 4069 g / m2or less, about 3390 g / m2or less, about 2710 g / m2or less and any range between and including the areal weight values provide.Table 4: Thermal Runaway Barrier Properties and Performance

[0032] The thermal runaway barrier includes a textile composite containing a plurality of elastomer layers such as silicone layers that are designed to form a highly thermally insulative silica-silicate layer for thermal protection with active flame impingement cooling in the condensed phase and flame poisoning in the gas phase. The fabric layers are 4-harness satin weave layers that are designed to adsorb and disperse impact energy that is transmitted to the barrier via grit impact, while maintaining strength at high temperature. Alternating layers of elastomer and fabric work in conjunction, sometime sacrificially, to insulate, absorb combustion debris impact, while maintaining strength under extreme thermal events.

[0033] An exemplary thermal runaway barrier includes a woven fabric with a 4 harness satin weave that is fiberglass or consists essentially of silica. This woven fabric has an areal weight of 450 g / m2 and a thickness of 0.3mm, and a breaking strength of 1068 N / cm (MD) and 875 N / cm (XD). a. Base fabric construction (“structural roving component”) (base fabric, at least one layer1. 4 Harness Satin Weave fiberglass2. 450 gsm3. 0.3 mm thickness4. Breaking Strength 1.07kN / cm (610 lbf / in)(MD), 876N / cm (500 lbf / in)(XD)

[0034] The thermal runaway barrier according to Example 1 had a temperature resistance of 600°C, high strength and high flexibility relative to thickness per data in Table 3. The silicone formulation paired with a woven glass reinforcement in a multiple layer construct created a unique balance of high flexibility, high mechanical strength at high temperature, high impact energy damping and dispersing composite, high flame resistance via insulative char formation, active flame cooling and poisoning, flame and smoke suppressant chemistry with very low toxicity.

[0035] Effective char formation through polysiloxane oxidation woven together for strength with needle-like silicate in a continuous sheet, in contrast to weaker silicone formulationswhich fracture and break apart at this stage, with reinforcement for mechanical integrity and elongation forms a tough and insulative matrix when it expands. This layer subsequently entraps air to increase the thermal insulation resistance.

[0036] The flame retardants of the elastomer layer become oxidized by-products that are encapsulated in the matrix providing increased thermal resistance of the char layer by providing thermally stable oxides up to temperatures of 2,000°C.

[0037] When the first interior elastomer layer eventually cracks and cleaves from multiple rounds of high impact molten particulate blast, the subsequent exposed layers of fabric and coating then act as the protective barrier allowing the backside layers of silicone and fabric to effectively insulate and absorb impact.

[0038] The four-harness satin weave of the woven fabric layer provides more stretch and elongation than other comparable weaves to support this function of normal impact to lateral energy dissipation, so the composite is uniquely effective at decelerating and adsorbing high-energy impact forces in a low profile.

[0039] The use of multiple layers in the thermal runaway barrier maximizes damping performance as each individual layer functions independently to absorb and disperse impact force. Multiple layers also increase the thermal insulative effect by creating thermal interface resistance. Functional properties of flame cooling and poisoning, insulative char formation, and structural energy absorption, are able to activate in cycles as the flame facing layers degrade individually but supported the next thin profile, textile composite layer. This allows sufficient protection for containment and anti-propagation of the thermal runaway front in a lithium-ion battery pack.

[0040] The summary of the invention is provided as a general introduction to some of the embodiments of the invention and is not intended to be limiting. Additional example embodiments including variations and alternative configurations of the invention are provided herein.BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0041] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.

[0042] Figure 1 shows a perspective partial cut-away view of a battery pack having an exemplary thermal runaway barrier thereon.

[0043] Figure 2 shows a perspective view of an exemplary thermal runaway barrier comprising a textile composite of alternating layers of fabric and elastomer layers.

[0044] Figure 3 shows a top view of an exemplary woven fabric having warp yarns and weft yarns.

[0045] Figure 4 shows a side view of a torch and grit test.

[0046] Figures 5 to 8 shows photographs of samples from a flexural fatigue test.

[0047] Figure 9 shows a cross sectional image of exemplary thermal runaway barrier to show strikethrough.

[0048] Corresponding reference characters indicate corresponding parts throughout the several views of the figures. The figures represent an illustration of some of the embodiments of the present invention and are not to be construed as limiting the scope of the invention in any manner. Some of the figures may not show all of the features and components of the invention for ease of illustration, but it is to be understood that where possible, features and components from one figure may be included in the other figures. Further, the figures are not necessarily to scale, some features may be exaggerated to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to employ the present invention.DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0049] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Also, use of "a" or "an" are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

[0050] Certain exemplary embodiments of the present invention are described herein and are illustrated in the accompanying figures. The embodiments described are only for purposes of illustrating the present invention and should not be interpreted as limiting the scope of the invention. Other embodiments of the invention, and certain modifications, combinations and improvements of the described embodiments, will occur to those skilled in the art and all such alternate embodiments, combinations, modifications, improvements are within the scope of the present invention.

[0051] As shown in FIG. 1 , a battery assembly 10, includes a battery pack 25 with an exemplary thermal runaway barrier 40 configured to form a barrier enclosure around thebattery or battery pack. The battery thermal runaway barrier 12 is a textile composite 42 that is conformable and conforms to contours 28 of the covered item 20, the battery pack 21 that includes the battery modules, 21, 2T and 21”, each comprising one or more battery cells 22, 22’. A battery 23 may include a plurality of battery modules each having one or more battery cells. The batteries and battery modules may be connected in series or parallel to produce a required battery voltage and current for an application in the battery pack. The thermal runaway barrier may extend contiguously over and around each battery module, or contiguously over and around the plurality of battery module or pack. The battery thermal runaway barrier 12 may extend between the battery 23 and the battery case 24 of the battery assembly 10. The battery assembly 10 includes a pair of battery connections 26, 26’ that extend from the battery 23 for connection to an electronic device. A battery management system 27 includes a controller 29 to monitor a state of charge of the batteries and to manage charging and discharging of the battery. The battery thermal runaway barrier may extend between the batteries and the battery management system including the controller of the battery management system.

[0052] As shown in FIG. 2, an exemplary thermal runaway barrier 40, such as a battery thermal runaway barrier 12, comprises a textile composite 42 of alternating layers of fabric layers 70, 70’ and elastomer layers 50, 50’. The elastomer layer comprises an elastomer 52, which may include an elastomer additive 53, such as iron oxide, and the elastomer layer may also include a filler material 58, such as platelet filler as described herein. The thermal runaway barrier 40 has an interior surface 44, or surface configured to face a covered item, such as a battery, and an exterior surface 45. As shown, the elastomer layer 50 is configured on the interior surface 44 which is the battery pack or cell facing surface.

[0053] As shown in FIG. 3, a fabric layer 70 may be a woven fabric 72 having yarns 74, which may include warp yarns 80 and weft yarns 90 that are woven together. The warp yarns and weft yarns may be modified for improved thermal barrier protection.

[0054] Figure 4 shows a side view of a torch and grit test, according to test method UL2596, that exposes a textile composite 42 of a thermal runaway barrier 40, such as a battery thermal runaway barrier 12, to torch or flame and then a blast of grit in repetitive cycles until defects or holes are formed in the thermal runaway barrier, thermal runaway barrier and has a blast resistance of at least four cycles according to test method UL2596 Torch and Grit (TaG) method. The Torch and Grit (TaG) test method for battery enclosure materials screening for UL 2596 consists of constant 1300°C high pressure torch applied with 5 second AI2O3 grit blast every 15 seconds. 3+ cycles before breach is indicative of better performance in full module test. Designed as a more relevant method to replicate combination of high temperature, pressure, and mechanical impact during a thermal runaway event. The outer elastomer layer 50 oxidizes in a continuous sheet with highmechanical integrity and expands to form an insulative matrix. The first fabric layer 70 and subsequent elastomer layers dampen impact forces independently and insulate to protect the outer enclosure and surrounding components around the battery. The thermal runaway barrier 40 has four elastomer layers 50, 50’, 50” and 50”’, and three fabric layers 70, 70’ and 70” configured between elastomer layers.

[0055] Figures 5 to 8 show pictures of thermal runaway barrier material after a flexural fatigue resistance testing. The photos in FIGS. 5 to 8 demonstrate improved flexural fatigue toughness (thus mechanical strength) of this composite utilizing a satin weave glass fabric vs. a material at comparable thickness utilizing a plain weave glass fabric. These materials were assessed via ASTM D6182 for flexural fatigue resistance using a Bally Flexometer for 25,000 cycles.

[0056] Figure 5 shows a front side of a thermal runaway barrier that has fabric layers with a satin weave after 25K cycles of the flexural fatigue test described herein, (from left to right: Warp, Weft, Diagonal Cross Direction).

[0057] Figure 6 shows the back side of the thermal runaway barrier shown in FIG. 5, after 25K cycles of the flexural fatigue test described herein, (from left to right: Warp, Weft, Diagonal Cross Direction)

[0058] Figure 7 shows a front side of a thermal runaway barrier that has fabric layers with a plain weave C after 25K cycles of the flexural fatigue test described herein, (from left to right: Warp, Weft, Diagonal Cross Direction).

[0059] Figure 8 shows the back side of the thermal runaway barrier shown in FIG. 7 after 25K cycles of the flexural fatigue test described herein, (from left to right: Warp, Weft Direction). From this test, the satin weave has better resistance to flex fatigue than a plain weave.

[0060] Figure 9 shows a cross sectional image of exemplary thermal runaway barrier 40 to show levels of elastomer strikethrough for this textile composite. The elastomer 52 of the elastomer layer 50 is silicone and has an elastomer filler 53, such as iron oxide.

[0061] It will be apparent to those skilled in the art that various modifications, combinations and variations can be made in the present invention without departing from the scope of the invention. Specific embodiments, features and elements described herein may be modified, and / or combined in any suitable manner. Thus, it is intended that the present invention cover the modifications, combinations and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A thermal runaway barrier system comprising a thermal runaway barrier comprising: a) a textile composite comprising a plurality of layers comprising: i) a woven fabric layer comprising a woven fabric of high temperature yarns that are thermally stable to a temperature of at least 650°C according to ASTM D5034; ii) an elastomer layer comprising an elastomer; wherein the woven layer and elastomer layer are alternating; wherein the thermal runaway barrier has a thickness of no more than 3mm; wherein the thermal runaway barrier has a weight per unit area of no more than 3.4 kg / m2; wherein the thermal runaway barrier has a blast resistance of at least four cycles according to test method UL2596 Torch and Grit (TaG) Method; and wherein the thermal runaway barrier has a dielectric strength per unit thickness of at least 12 kV / mm; and a dielectric strength of at least 3.1 kV / mm after a thermal runaway event, according to ASTM D149 Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials.

2. The thermal runaway barrier of claim 1, wherein the thermal runaway barrier has a heat of combustion of at least 25 MJ / kg according to ASTM 1354.

3. The thermal runaway barrier of claim 1, wherein the thermal runaway barrier is conformable having a nominal bending moment of less than 0.10 N m as measured via ASTM D747 cantilever method.

4. The thermal runaway barrier of claim 1, wherein the thermal runaway barrier has a puncture resistance of 300 cm-kgf or more according to test method ASTM D751.

5. The thermal runaway barrier of claim 1 , wherein the plurality of layers of the textile composite comprise four layers including two elastomer layers and two woven fabric layers.

6. The thermal runaway barrier of claim 1 , wherein the plurality of layers of the textile composite comprise between 2 to 50 layers.

7. The thermal runaway barrier of claim 1, wherein the thermal runaway barrier has a thickness of no more than 4 mm.

8. The thermal runaway barrier of claim 1, wherein the thermal runaway barrier has a thickness of no more than 3 mm.

9. The thermal runaway barrier of claim 1, wherein the thermal runaway barrier has a thickness of no more than 2 mm.

10. The thermal runaway barrier of claim 9, wherein each of the elastomer layers has a thickness of no more than 0.7 mm.11 . The thermal runaway barrier of claim 10, wherein each of the fabric layers has a thickness of no more than 0.7 mm.

12. The thermal runaway barrier of claim 9, wherein each of the elastomer layers has a thickness of no more than 0. 6mm.

13. The thermal runaway barrier of claim 12, wherein each of the fabric layers has a thickness of no more than 0.6 mm.

14. The thermal runaway barrier of claim 9, wherein each of the fabric layers has a thickness of no more than 0.7 mm.

15. The thermal runaway barrier of claim 9, wherein each of the fabric layers has a thickness of no more than 0.6 mm.

16. The thermal runaway barrier of claim 1, wherein the thermal runaway barrier has an interior surface and wherein an elastomer layer of said plurality of elastomer layers is configured along the interior surface.

17. The thermal runaway barrier of claim 1, wherein the high temperature yarns comprise silicon dioxide.

18. The thermal runaway barrier of claim 1, wherein the high temperature yarns comprise a substantial portion of silicon dioxide including at least 50% by weight silicone dioxide.

19. The thermal runaway barrier of claim 1, wherein the high temperature yarns comprise aluminum oxide.

20. The thermal runaway barrier of claim 1, wherein the high temperature yarns have a concentration by weight of said aluminum oxide of at least 15%.21 . The thermal runaway barrier of claim 20, wherein the high temperature yarns comprise calcium oxide.

22. The thermal runaway barrier of claim 21 , wherein the high temperature yarns have a concentration by weight of said calcium oxide of at least 15%.

23. The thermal runaway barrier of claim 22, wherein the high temperature yarns comprise di boron trioxide.

24. The thermal runaway barrier of claim 23, wherein the high temperature yarns have a concentration by weight of said diboron trioxide of at least 5%.

25. The thermal runaway barrier of claim 24, wherein the high temperature yarns comprise magnesium oxide.

26. The thermal runaway barrier of claim 25, wherein the high temperature yarns have a concentration by weight of said magnesium oxide of at least 1%.

27. The thermal runaway barrier of claim 1, wherein the high temperature yarns consist essentially of silica, having a concentration by weight of silica of at least 90%.

28. The thermal runaway barrier of claim 1, wherein the high temperature yarns include components selected from the group consisting of: silicon dioxide, aluminum oxide, calcium oxide, diboron trioxide, and magnesium oxide.

29. The thermal runaway barrier of claim 1, wherein the woven fabric layer includes warp yarns and weft yarns and wherein the warp yarns are a different material composition from the weft yarns.

30. The thermal runaway barrier of claim 1, wherein the thermal runaway barrier has a puncture resistance of at least 300 cm-kgf according to ASTM D751.31 . The thermal runaway barrier of claim 30, wherein the thermal runaway barrier has a torch and grit performance of at least four cycles according to UL2596.

32. The thermal runaway barrier of claim 1, wherein the thermal runaway barrier has a torch and grit performance of at least four cycles according to UL2596.

33. The thermal runaway barrier of claim 1, wherein the high temperature yarns of the woven fabric consists of fiberglass high temperature yarns and the elastomer layer comprises silicone.

34. The thermal runaway barrier of claim 1, wherein the thermal runaway barrier has a heat of combustion of at least 25 MJ / kg according to ASTM 1354. wherein the thermal runaway barrier is conformable having a nominal bending moment of less than 0.10 N m as measured via ASTM D747 cantilever method. wherein the thermal runaway barrier has a puncture resistance of 300 cm-kgf or more according to test method ASTM D751.

35. The thermal runaway barrier of claim 34, wherein the thermal runaway barrier has a puncture resistance of at least 300 cm-kgf according to ASTM D751 .

36. The thermal runaway barrier of claim 35, wherein the thermal runaway barrier has a torch and grit performance of at least four cycles according to UL2596.

37. The thermal runaway barrier of claim 34, wherein the thermal runaway barrier has a torch and grit performance of at least four cycles according to UL2596.

38. The thermal runaway barrier of any one of claims 1 to 37, wherein the elastomer consists of silicone.

39. The thermal runaway barrier of any one of claims 1 to 37, wherein the elastomer comprises silicone.

40. The thermal runaway barrier of claim 39, wherein the silicone comprises filler particles.41 . The thermal runaway barrier of claim 40, wherein the silicone is a high molecular weight vinyl polysiloxane.

42. The thermal runaway barrier of claim 40, wherein the filler particles comprising iron oxide.

43. The thermal runaway barrier of claim 42, wherein the silicone is a high molecular weight vinyl polysiloxane.

44. The thermal runaway barrier of claim 39, wherein the silicone comprises a flame retardant.

45. The thermal runaway barrier of claim 44, wherein the flame retardant comprises vinyl silane.

46. The thermal runaway barrier of claim 44, wherein the flame retardant comprises at least one of magnesium and aluminum hydroxide.

47. The thermal runaway barrier of claim 44, wherein the flame retardant comprises zinc phosphate.

48. The thermal runaway barrier of claim 44, wherein the flame retardant is selected from the group consisting of: zinc phosphate, magnesium, aluminum hydroxide and vinyl silane.

49. The thermal runaway barrier of claim 44, wherein the flame retardant comprises zinc phosphate, magnesium, aluminum hydroxide and vinyl silane.

50. The thermal runaway barrier of claim 44, wherein the silicone comprises filler particles.51 . The thermal runaway barrier of claim 50, wherein the silicone is a high molecular weight vinyl polysiloxane.

52. The thermal runaway barrier of claim 44, wherein the silicone comprises a flame poisoning material.

53. The thermal runaway barrier of claim 52, wherein the flame poisoning material comprises organophosphorus.

54. The thermal runaway barrier of claim 39, wherein the silicone comprises platelet filler particles having an aspect ratio of length and width to thickness of 3:1 or more.

55. The thermal runaway barrier of claim 54, wherein the platelet filler particles are selected from the group consisting of phlogopite mica, boron nitride, and graphite to graphene.

56. The thermal runaway barrier of claim 55, wherein the platelet filler particles are in a concentration by weight of the elastomer layer of 20% or more.

57. The thermal runaway barrier of claim 55, wherein the platelet filler particles are in a concentration by weight of the elastomer layer between 20% to 75%.

58. The thermal runaway barrier of claim 54, wherein the platelet filler particles are in a concentration by weight of the elastomer layer between 20% to 75%.

59. A battery thermal runaway barrier system comprising: a) a battery pack comprising a plurality of battery cells; and b) a thermal runaway barrier according to any one of the claims 1 to 37, wherein the thermal runaway barrier is configured around said battery cell.

60. The battery thermal runaway barrier of claim 59, wherein the elastomer consists of silicone.61 . The thermal runaway barrier of claim 59, wherein the elastomer comprises silicone.

62. The thermal runaway barrier of claim 61 , wherein the silicone comprises filler particles.

63. The thermal runaway barrier of claim 62, wherein the silicone is a high molecular weight vinyl polysiloxane.

64. The thermal runaway barrier of claim 62, wherein the filler particles comprising iron oxide.

65. The thermal runaway barrier of claim 64, wherein the silicone is a high molecular weight vinyl polysiloxane.

66. The thermal runaway barrier of claim 61 , wherein the silicone comprises a flame retardant.

67. The thermal runaway barrier of claim 62, wherein the flame retardant comprises vinyl silane.

68. The thermal runaway barrier of claim 66, wherein the flame retardant comprises at least one of magnesium and aluminum hydroxide.

69. The thermal runaway barrier of claim 66, wherein the flame retardant comprises zinc phosphate.

70. The thermal runaway barrier of claim 66, wherein the flame retardant is selected from the group consisting of: zinc phosphate, magnesium, aluminum hydroxide and vinyl silane.71 . The thermal runaway barrier of claim 66, wherein the flame retardant comprises zinc phosphate, magnesium, aluminum hydroxide and vinyl silane.

72. The thermal runaway barrier of claim 66, wherein the silicone comprises filler particles.

73. The thermal runaway barrier of claim 72, wherein the silicone is a high molecular weight vinyl polysiloxane.

74. The thermal runaway barrier of claim 73, wherein the silicone comprises a flame poisoning material.

75. The thermal runaway barrier of claim 74, wherein the flame poisoning material comprises organophosphorus.

76. The thermal runaway barrier of claim 61 , wherein the silicone comprises platelet filler particles having an aspect ratio of length and width to thickness of 3:1 or more.

77. The thermal runaway barrier of claim 76, wherein the platelet filler particles are selected from the group consisting of phlogopite mica, boron nitride, and graphite to graphene.

78. The thermal runaway barrier of claim 77, wherein the platelet filler particles are in a concentration by weight of the elastomer layer of 20% or more.

79. The thermal runaway barrier of claim 77, wherein the platelet filler particles are in a concentration by weight of the elastomer layer between 20% to 75%.

80. The thermal runaway barrier of claim 76, wherein the platelet filler particles are in a concentration by weight of the elastomer layer between 20% to 75%.81 . The battery thermal runaway barrier of claim 59, wherein the thermal runaway barrier is conformable having a nominal bending moment of less than 0.10 N m as measured via ASTM D747 cantilever method.

82. The battery system of claim 81 , wherein the thermal runaway barrier conforms to a radius of curvature of said battery of no more than 10mm.

83. The battery thermal runaway barrier system of claim 82, wherein the battery further comprises a plurality of battery cells and wherein the thermal runaway barrier extends contiguously around each of said plurality of battery cells.

84. The battery thermal runaway barrier system of claim 83, wherein the battery further comprises a battery management system.

85. The battery thermal runaway barrier system of claim 84, wherein the thermal runaway barrier extends between the plurality of battery cells and module and the battery management system.

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