EP4677683A1

EP4677683A1 - Improved thermal barrier elasticity

Info

Publication number: EP4677683A1
Application number: EP24767899.8A
Authority: EP
Inventors: Tien T. Wu; Claus H.G. Middendorf; Carsten AMELUNGK; Shailendra B. Rathod; Gerry A. Hoffdahl; Andrew C. CLAUSEN; Jeffrey P. KALISH; Nathan E. Schultz; Michelle M. MOK
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2023-03-09
Filing date: 2024-03-08
Publication date: 2026-01-14
Also published as: WO2024187089A1; CN120917602A

Abstract

A thermal barrier that has improved compression performance is disclsoed along with a method of making such articles. The thermal barrier article, comprising: at least one layer of a nonwoven fibrous thermal insulation comprising: (a) a fiber matrix of inorganic fibers; (b) a plurality of thermally insulative inorganic particles dispersed within the fiber matrix; (c) a binder dispersed within the fiber matrix so as to hold together the fiber matrix; and (d) a plurality of compressible organic particles dispersed within the fiber matrix. The thermal barriers can be used in battery assemblies.

Description

IMPROVED THERMAL BARRIER ELASTICITY

[0001] The present invention relates to a barrier for at least significantly slowing down a thermal runaway event within a battery assembly, e.g., like a battery assembly used in an electric vehicle. The barrier as described herein contains compressible organic particles and exhibits an improved elasticity. Furthermore, the present invention relates to a method for producing the barrier.

BACKGROUND

[0002] Electric motors used in electric or hybrid vehicles (e.g.. automobiles) are powered, at least in part, by batteries. Lithium-ion batteries arc typically used in such applications. These batteries arc disposed within the vehicle compactly to save space. Typically, the lithium-ion batteries comprise a battery' module or assembly of individual battery cells. In an unfortunate circumstance, these batteries may experience a thermal runaway condition, where one of tire cells malfunctions due to a variety of reasons and generates a large amount of heat. The heat can get transferred to the adjoining functioning cells and make them malfunction. The heat can also start a fire. Under such circumstances, the complete battery module can ignite due to the propagation of the heat, eventually engulfing the vehicle, creating a safety hazard to the vehicle, the occupant of the vehicle, and the surroundings of the vehicle. Global regulatory bodies are moving towards enforcing a regulation that would require the battery manufacturers to isolate the malfunctioning cell, thereby avoiding spreading the heat to adjoining cells, and provide the occupants of a vehicle a certain amount of time to evacuate the vehicle. One strategy to meet these requirements is to use a thermal barrier between cells that can delay the thermal runaway propagation.

[0003] A thermal barrier also needs to provide cushioning properties during the normal application of the battery module. The thermal barrier needs to fit snugly between the cells and occupy the gap between the cells. In other words, the thermal barrier needs to apply a certain pressure on the cell. Further complicating the situation, as the cells age, there is a permanent swelling of cells which translates into a decrease in the gap between the cells over the life of the cell. In other words, the thermal barrier needs to meet both the beginning-of-life (BOL) and end-of-life (EOL) pressures exerted by’ the battery' cells, when placed between the cells. If the pressure exerted by the thermal barrier is lower than the required pressures, then the thermal barrier does not fit snugly. If the pressure exerted by the thermal barrier is higher than the required pressures, then the cells can malfunction.

[0004] Patent Publications WO 2022/024076 Al, WO 2022/024078 Al, and WO 2022/024085 Al propose non-woven webs with low thermal conductivity' fillers, such as aerogels and fumed silica, dispersed in the web to be used as a thermal barrier to prevent heat from the malfunctioning cell to spread to the other parts of the battery module. The disclosed materials comprise a matrix of inorganic fibers and are thermally stable at temperatures of thermal runaway conditions. A drawback of such non-woven web based thermal barrier is that their compression profile does not meet the requirements for cushioning. Typically, they satisfy requirements for either BOL or EOL pressure, but not both. If the thermal barrier meets the BOL pressure, then the pressures exerted at EOL by the webs are higher than what is needed. If the thermal barrier meets the EOL pressure, then the pressures exerted at BOL by the webs are lower than what is needed. In other words, the compression curve needs to be flatter. Hence, the compression performance of thermal barriers based on non-woven webs needs to be improved.

SUMMARY

[0005] There is a need for a thermal barrier being thermally stable at temperatures of thermal runaway conditions and having improved compression performance.

[0006] In one aspect, a thermal barrier is provided that is operatively adapted for being disposed between battery cells of a battery assembly and for at least significantly slowing down a thermal runaway event within the battery assembly. The thermal barrier comprises a layer of a nonwoven fibrous thermal insulation comprising a fiber matrix of inorganic fibers, thermally insulative inorganic particles and compressible organic particles dispersed within the fiber matrix, and a binder dispersed within the fiber matrix so as to hold together the fiber matrix. Thus, the thermal barrier as described herein exhibits a certain and improved elasticity. An optional organic encapsulation layer may also be included for encapsulating the layer of nonwoven fibrous thermal insulation.

[0007] In another aspect, a battery cell module or assembly for an electric vehicle is provided. The battery cell module or assembly comprises a plurality of battery cells disposed in a housing, and a plurality’ of thermal barriers according to the present invention. The battery cells are lined up in a row or stack, with one thermal barrier being disposed between each pair of adjacent battery’ cells, or between a pre-determined number of battery’ cells (e.g., after every third battery cell), or between battery modules.

[0008] In a further aspect, a method is provided for making a thermal barrier according to the present invention, where the method comprises forming the layer of nonwoven fibrous thermal insulation using a wet-laid process or dry -laid process.

[0009] The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present disclosure is explained in more detail on the basis of the drawings, in which

[0011] Figure 1 is a schematic end view of thermal barrier as disclosed herein;

[0012] Figure 2 is a schematic end view of a battery cell module as disclosed herein, with thermal barriers as disclosed herein disposed between adjacent battery cells;

[0013] Figure 3 is a schematic top view of a battery pack of battery cell modules as disclosed herein, with thennal barriers placed between adjacent battery modules and/or on the top of the battery modules;

[0014] Figure 4 is a photographic perspective view of a thermal barrier as disclosed herein, the thermal barrier being encapsulated with an adhesive-backed organic polymeric layer with release liners and an expanding gas outlet/notch; and

[0015] Figure 5 is a schematic side view of a dry-laid process for manufacturing a thermal barrier as disclosed herein, according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

[0016] In describing preferred embodiments of the invention, specific terminology is used for the sake of clarity . The invention, however, is not intended to be limited to the specific terms so selected, and each term so selected includes all technical equivalents that operate similarly .

[0017] As used herein, the terms “preferred” and “preferably” refer to embodiments described herein that can afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the invention.

[0018] As used herein and in the appended claims, the singular forms “a,” "an.” and "die” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a” or “the” component may include one or more of the components and equivalents thereof known to those skilled in the art. Further, the term “and/or” means one or all the listed elements or a combination of any two or more of the listed elements.

[0019] It is noted that the term “comprises” and variations thereof do not have a limiting meaning where these terms appear in the accompanying description and shall include the terms “consisting essentially of’ and “consisting of’.

[0020] As used herein, the term “consisting of’ indicates that the claimed thermal barrier only covers structures with the recited elements.

[0021] As used herein, the term “consisting essentially of indicates that the claimed thennal barrier is able to exhibit the desired thermal insulation properties by using only the recited features/elements, without the need for additional layers of thermal insulation material. For example, the present inventive thermal barrier does not need to include another layer of other thermal insulation material (e.g., a woven fabric or nonwoven structure of inorganic fibers). Therefore, with the “consisting essentially of’ language, if a third party thermal barrier (e.g., of a competitor) includes all of the features/elements in a claim of the present invention, as well as one or more additional features/elements (e.g., an additional layer of inorganic fibers) not recited in the claim, that third party thermal barrier is considered covered by the claim, if the additional feature/element does not determine whether the desired thermal insulation and compression properties will be exhibited by the thermal barrier.

[0022] Relative terms such as top, bottom, side, upper, lower, horizontal, vertical, and the like may be used herein and, if so, are from the perspective observed in the drawing. These terms are used only to simplify the description, however, and not to limit the scope of the invention in any way.

[0023] Reference throughout this specification to “one embodiment,” “certain embodiments,” “one or more embodiments” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases such as “in one or more embodiments.” “in certain embodiments,” “in one embodiment” or "in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the invention.

[0024] As used herein, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.

[0025] Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0026] “Ambient conditions” means at 25°C and 101.3 kPa pressure.

[0027] “Average” means number average, unless otherw ise specified.

[0028] “Cure” refers to exposing to radiation in any form, heating, or allowing to undergo a physical or chemical reaction that results in hardening or an increase in viscosity.

[0029] “Size” refers to the longest dimension of a given object or surface.

[0030] “Substantially” means to a significant degree, as in an amount of at least 50%. 60, 70, 80, 90. 95. 96, 97. 98, 99, 99.5, 99.9. 99.99, or 99.999%, or 100%.

[0031] “Thickness” means the distance between opposing sides of a layer or multilayered article.

[0032] The recitation of numerical ranges by endpoints includes all numbers subsumed within that range in increments commensurate with the degree of accuracy indicated by the end points of the specified range (e.g., for a range of from 1.000 to 5.000, the increments will be 0.001, and the range will include 1.000, 1.001, 1.002, etc., 1.100, 1.101, 1.102, etc., 2.000, 2.001, 2.002, etc., 2.100, 2.101, 2.102, etc., 3.000. 3.001, 3.002, etc., 3.100, 3.101, 3.102, etc., 4.000, 4.001, 4.002, etc., 4.100, 4.101, 4.102, etc., 5.000, 5.001. 5.002, etc. up to 5.999) and any range within that range, unless expressly indicated otherwise. [0033] The term “polymer” will be understood to include polymers, copolymers (e.g., polymers formed using two or more different monomers), oligomers and combinations thereof, as well as polymers, oligomers, or copolymers that can be formed in a miscible blend.

[0034] The thermal barrier is operatively adapted (i.e., designed, configured, shaped and/or dimensioned) or otherwise suitable for being disposed betw een adjacent battery cells of a battery module or assembly (i.e., a series of battery cells stacked together in a row) such as that used to power an electric motor (e g., like that used in an electric or hybrid vehicle).

[0035] The thennal barrier as disclosed herein may prevent, stop, or can at least significantly slow down a thennal runaway event within the battery module or assembly or between adjacent battery modules or assemblies.

[0036] A "thermal runaway” is when a battery cell experiences an exothennic chain reaction causing the phenomenon of an uncontrollable temperature rise of the battery cell. The exothermic chain reaction may be caused, for example, by over-heating of the battery cell, over-voltage of the battery cell, and mechanical puncture of the battery cell, among other reasons.

[0037] A “thermal propagation” is when a battery cell thermal rimaway causes the remaining battery cells in a battery module or assembly to imdergo the thermal runaway phenomenon.

[0038] A “thermal runaway event” refers to the overheating of one battery cell, in a battery module or assembly of battery cells, causing a chain reaction of adjacent battery cells overheating, and potentially exploding or catching fire, until the number of overheated battery cells reaches a critical point of propagation resulting in all or more than half of the battery cells in the module or assembly of modules being destroyed. Factors that can cause a battery cell to overheat include: physical damage, applying over voltage, overheating (internal battery cell shorting).

[0039] As the energy density of a battery cell increases, the temperature at which the battery' cell starts to malfunction (e.g., from at least losing its efficiency or failing to function up to igniting, burning or exploding) decreases. Likewise, as the energy density of the battery cell decreases, the temperature at which the battery cell starts to malfunction increases. For example, with a controlled ramping up of the temperature. NMC811 type battery cells tend to start malfunctioning or even blow up when the temperature reaches around 120 °C to 130 °C, while NMC622 ty pe battery cells start to malfunction or even blow up when they reach a temperature of around 180 °C. The corresponding temperature is higher for battery cells with lower energy densities (e.g., NMC532 and NMC433 ty pe battery cells). With physically larger battery cells or when the temperature is rapidly increased, thermal diffusion through the battery' cell can result in the localized temperature taking longer to get up to the critical point. It is believed that this thermal diffusion effect can cause the actual temperature at which the battery cell starts to malfunction of blow up to be somewhat higher. It can be desirable for the thermal barrier of the present disclosure to prevent an adjacent battery from reaching a temperature in the range of from about 130 °C up to about 150 °C. [0040] As used herein, “preventing” a thermal runaway event refers to preventing the overheating of a single battery cell from causing the overheating of battery cells that are adjacent to the single battery cell. The thermal barrier is considered to prevent a thermal rimaway event, when adjacent battery cells do not reach above 130 °C, 135 °C, 140 °C, 145 °C, or 150 °C.

[0041] As used herein, “stopping” a thermal runaway event refers to the overheating of a battery cell only causing adjacent battery cells (i.e., three, two or even only one battery cell away on either side of the overheating battery' cell) to overheat and the remaining battery cells in the battery module or assembly do not overheat.

[0042] As used herein, “slowing down” a thennal runaway event refers to the thermal runaway event being slowed down at least long enough to allow personnel adjacent to the battery' module or assembly (e.g., an occupant inside of an electric vehicle passenger compartment) to escape to a safe distance away from the battery module or assembly, before being injured by the thermal runaway event. Once a battery cell malfunctions (e.g.. is on fire or overheats to the point of not functioning) and a thennal barrier is in place between battery cells, the time for any adjacent battery cells to propagate the malfunction (e.g.. catching fire or overheating) is at least more than 5 minutes, and preferably more than 10 minutes or even 20 minutes or more.

[0043] The thermal barrier of the present disclosure is directed toward a nonwoven fibrous thermal insulation material comprising (a) a fiber matrix of inorganic fibers; (b) a plurality of thennally insulative inorganic particles dispersed within the fiber matrix; (c) a plurality of compressible organic particles dispersed within the fiber matrix, and (c) a binder dispersed within the fiber matrix so as to hold together the fiber matrix.

[0044] The thermal barrier disclosed herein comprises a layer of a nonwoven fibrous thermal insulation comprising a fiber matrix of inorganic fibers. The thermal barrier may comprise only one or more layers of a nonwoven fibrous thennal insulation comprising a fiber matrix of inorganic fibers. The nonwoven fibrous thennal insulation may be dry -laid or wet-laid. The nonwoven fibrous thermal insulation may be in the form of a mat, sheet, strip, or three-dimensional thin-walled structure.

[0045] As used herein, the term “inorganic” refers to ceramic or otherwise nonmetallic (i.e., not a metal, metal alloy, or metal composite) inorganic material.

[0046] The inorganic fibers typically have a mean aspect ratio, i.e., a mean length to diameter ratio, of greater than 2500. The mean aspect ratio of the inorganic fibers may be from greater than 2500 to up to 70000. or from greater than 2500 to up to 50000. or from 3000 to 70000, or from 3000 to 50000. or from 5000 to 70000. or from 5000 to 50000, or from 8000 to 70000. or from 8000 to 50000. The mean aspect ratio of the inorganic fibers may also be greater than 70000. [0047] The mean aspect ratio is measured by measuring length and diameter of individual fibers on scanning electron micrographs and calculating the aspect ratio, i.e., the length to diameter ratio. The aspect ratio of 50 individual fibers is determined and the average value is calculated.

[0048] The diameter of the inorganic fibers may be from 1 to 20 pm. The length of the inorganic fibers may be from 1 mm to 400 mm, or more.

[0049] The inorganic fibers of the fiber matrix may be selected from the group of fibers consisting of alkaline earth silicate fibers, refractory ceramic fibers (RCF), poly crystalline wool (PCW) fibers, basalt fibers, glass fibers, silica fibers, and combinations thereof. Glass fibers and silica fibers typically do not contain any or only nominal shot particles. PCW typically contains a maximum of 5% shot particles, while alkaline earth silicate (AES) fibers contain up to 60% shot particles when uncleaned and as low as 10% - 30% minimum shot particles when cleaned. Shot particles consist of globular grains that were not turned into fiber during the manufacturing process.

[0050] The layer of nonwoven fibrous thennal insulation may comprise an amount of inorganic fibers in the range of from 15 percent by weight to 90 percent by weight, or from 15 percent by weight to 70 percent by weight, or from 20 percent by weight to 90 percent by weight, or from 20 percent by weight to 80 percent by weight, or from 20 percent by weight to 70 percent by weight, or from 30 percent by weight to 60 percent by weight, or from 35 percent by weight to 55 percent by weight, based on the total weight of the nonwoven fibrous thermal insulation.

[0051] The layer of nonwoven fibrous thermal insulation of the thermal barrier disclosed herein comprises a plurality of thermally insulative inorganic particles and a plurality of compressible organic particles dispersed within the fiber matrix.

[0052] The plurality of particles may be dispersed evenly, uniformly, generally or otherwise throughout or to the extent permitted by the manufacturing process (e.g.. there can be a little sedimentation of the particles on the bottom of the mat in both the dry' laid and wet laid processes) within the fiber matrix.

[0053] The thermally insulative inorganic particles may comprise particles selected from the group consisting of inorganic aerogel, xerogel, hollow or porous ceramic microspheres, unexpanded vermiculite, irreversibly or permanently expanded vermiculite, fumed silica, otherwise porous silica, irreversibly or permanently expanded or unexpanded perlite, pumicite. irreversibly or permanently expanded clay, diatomaceous earth, titania, zirconia, and combinations thereof. The inorganic particles can be solid, hollow or contain multiple voids. Such particles can include, e.g.. particles of unexpanded intumescent material, irreversibly or permanently expanded expandable materials (e.g.. intumescent material), diatomaceous earth, inorganic aerogel material, porous ceramic (e.g., silica) material, irreversibly or permanently' expanded perlite mineral, hollow ceramic or otherwise inorganic (e.g.. glass) microspheres, etc. Such inorganic particles that contain voids such as. e.g., those found in irreversibly or permanently expanded vermiculite are particularly desirable. Particles of irreversibly or permanently expanded perlite mineral also contain voids, but perlite mineral is harder and less compressible than vermiculite mineral. Silica-based and other aerogel particles also contain voids.

[0054] The particles of fumed silica may have a specific surface area in the range of from about 100 m²/g up to about 400 m²/g.

[0055] As used herein, an irreversibly or permanently expanded expandable particle (e.g., particle of an intumescent material such as vermiculite and perlite mineral) refers to a particle that has been heated to a temperature and for a time that causes the particle to irreversibly or permanently expand to at least 10% and up to 100% of its expandability, either by being pre-expanded before being used to form the thermal barrier, or post-expanded after it is incorporated into the nonwoven fibrous thermal insulation.

[0056] Intumescent particles (e.g., vermiculite particles) can be permanently expanded by overheating the particles to beyond the point of reversibility (e.g., in the range of from about 350 °C up to about 1000 °C for vermiculite). Such a permanently expanded intumescent particle (e.g., vermiculite particle) can have an expanded accordion or worm-like structure that is easier to break apart into smaller particles, compared to the same particle in its unexpanded state, because of its elongated geometry, lower density and lower mechanical stability. As the heating temperature increases, the degree of permanent expansion of the particle increases (i.e.. the particles can get larger and/or longer). It may also be desirable to use vermiculite that has been permanently expanded by a chemical treatment method (see, e.g., “Chemical Exfoliation of Vermiculite and the Production of Colloidal Dispersions”. G.F. Walker, W.G. Garrett. Science 21Aprl967: Vol. 156, Issue 3773. pp. 385-387).

[0057] Because they are easier to break apart in their expanded state, it can be desirable to post-expand the intumescent particles, after the unexpanded intumescent particles have been incorporated into the nonwoven fibrous thermal insulation. Even if gentle processing is employed so as not to substantially break them apart, it is believed that incorporating pre-expanded intumescent particles into the nonwoven fibrous thermal insulation can still result in the expanded particles becoming oriented into the plane (i.e., x-axis, y- axis, and/or therebetween) of the insulation. For example, with pre-expanded vermiculite particles, the elongated particles can become generally aligned with the fibers in the longitudinal or downstream direction (i.e., y-axis), rather than in the thickness direction (i.e., z-axis), of the nonwoven fibrous thermal insulation. [0058] In contrast, when they are post-expanded (i.e., after the nonwoven fibrous thermal insulation is made with unexpanded intumescent particles), the expanded intumescent particles are not oriented primarily in the plane of the insulation. Unexpanded intumescent particles typically have a more uniform structural geometry (i.e., have an aspect ratio closer to 1) compared to the same particles in its expanded state. It is believed that this more uniform structural geometry is less likely to be influenced by the alignment of the inorganic fibers during the formation of the nonwoven fibrous thermal insulation. As a result, the post-expanded intumescent particles are more likely to be oriented isotropically within the nonwoven fibrous thermal insulation. For example, with post-expanded vermiculite particles, the elongated particles can become aligned in the thickness direction (i.e., z-axis), in plane (i.e., x-axis. y-axis, and/or therebetween), or off-axis thereof. It is believed this difference between the orientation of pre-expanded particles versus post-expanded particles is caused by the unexpanded particles having a more uniform structural geometry than that exhibited while in their expanded state.

[0059] The layer of nonwoven fibrous thermal insulation may comprise the thermally insulative particles in an amount of at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 35% by weight, based on the total weight of the nonwoven fibrous thermal insulation. The layer of nonwoven fibrous thermal insulation may comprise the thermally insulative particles in an amount of up to 40%, or up to 45%, or up to 50%, or up to 55%, or up to 60% by weight, based on the total weight of the nonwoven fibrous thermal insulation. For example, a particle content as high as 60% by weight can be achieved using a dry-laid process, and as high as 50% by weight using a wet-laid process. The layer of nonwoven fibrous thermal insulation may comprise the plurality of thermally insulative inorganic particles in an amount of from 10 percent by weight to 60 percent by weight, based on the total weight of the nonwoven fibrous thermal insulation.

[0060] The layer of nonwoven thermal insulation of the thermal barrier disclosed herein comprises a binder dispersed within the fiber matrix so as to hold together the fiber matrix. The binder may be an organic or inorganic binder, e.g., an organic or inorganic adhesive binder, organic or inorganic binder fibers that are needle punched, stitched or otherwise mechanically entangled into the fiber matrix so as to hold together the fiber matrix. The binder may be dispersed evenly, uniformly, generally or otherwise throughout or to the extent permitted by the manufacturing process within the fiber matrix so as to bond together the inorganic fibers and thermally insulative particles and the compressible organic particles or otherwise hold together the fiber matrix for as long as needed to at least survive the degree of handling required (e.g.. during the encapsulation process) before being installed between battery cells.

[0061] Inorganic binders, organic binders, or a combination of both can be useful according to the present disclosure and may include, e.g., those disclosed in U.S. Pat. No. 8,834,759. An example of an inorganic binder useful in both dry -laid or wct-Iaid fiber processing can include particles of silicone that convert to fusible silica when heated. An organic-inorganic hybrid binder may also be useful such as, e.g., those available under the trade designation “Wacker MQ 803 TF”, which is a co-hydrolysis product of tetraalkoxy silane (Q unit) and trimethyl-alkoxy silane (M unit). The chemical structure of Wacker MQ 803 TF can be seen as a three dimensional netw ork of polysilicic acid units which are end-blocked with trimethylsilyl groups. Some residual ethoxy and hydroxy functions are present. The average molecular weight can be exactly controlled by the ratio of M and Q units. This ratio approximately is 0.67 for Wacker MQ 803 TF.

[0062] The binder dispersed within the fiber matrix may be in the form of polymer fibers. Advantageously, the binder may be in the form of bicomponent core-sheath polymer fibers, such as core-sheath polyester/polyethylene fibers. The polymer fiber binder does not lose its fibrous form during the process of making the thermal barrier.

[0063] Exemplary binder fibers include the use of bicomponent core-sheath polymeric fibers in a dry -laid process. In a wet-laid process, ethylene vinyl acetate latex dispersion binder, bicomponent core-sheath poly meric fibers, or a combination of both can be used. When a polymeric binder fiber is used, the binder can be activated by heating and compressing the nonwoven fibrous thermal insulation material. A combination of organic and inorganic binder can also be used.

[0064] The organic binders as used for the thermal barrier disclosed herein may be in the form of polymer fibers (e.g., PE/PET, PET, FRPET, such as those available under the trade designation ’‘T255” from Trevira), dry' polymer powder (e.g., LDPE, polyamide, epoxy resin powder (available under the trade designation

“3M Scotchcast 265”, ”3. VI Scotchkote 6258” from 3M CO., St. Paul, MN)), or a liquid binder (e.g., acylic latex, ethylene vinyl acetate (EAF68) latex, silicone, polyurethane etc.).

[0065] The layer of nonwoven fibrous thermal insulation may comprise the binder in an amount of at least 2.5%. at least 3.0%, at least 4.0%. at least 4.5%. at least 5.0%, at least 5.5%. at least 6.0%. or at least 6.5% by weight, based on the total weight of the nonwoven fibrous thermal insulation. The layer of nonwoven fibrous thermal insulation may comprise the binder in an amount of up to 7.0%. up to 7.5%. up to 8.0%, up to 8.5%, up to 9.0%, up to 9.5%, up to 10%, up to 15%. or up to 20% by weight, based on the total weight of the nonwoven fibrous thermal insulation. The layer of nonwoven fibrous thermal insulation may comprise the binder in an amount of from 2.5% by weight to 15% by weight, or from 2.5% by weight to 20% by weight, based on the total weight of the nonwoven fibrous thermal insulation.

[0066] The layer of nonwoven fibrous thermal insulation of the thermal barrier disclosed herein further comprises a plurality of compressible organic particles dispersed within the fiber matrix.

[0067] The compressible organic particles may be selected from hollow organic microspheres or solid organic microspheres. Exemplary compressible organic particles include expanded microspheres, rubber particles, foam particles, silicone particles, polyurethane particles, styrenic block copolymer particles, and any combinations and mixtures thereof.

[0068] In some embodiments, the compressible organic particles are selected from hollow organic microspheres, preferably from expandable hollow organic microspheres and expanded hollow organic microspheres. In general, the hollow organic microspheres comprise a thermoplastic polymeric shell and a core comprising a liquid or gas. Expandable organic microspheres are activated at a certain temperature at which the thermoplastic polymeric shell softens and the core expands. The expansion of the core liquid leads to an expansion of the whole microsphere, i.e., to an increase of its volume. The polymeric shell preferably contains a thermoplastic shell composition comprising compounds selected from acry lonitrile, methacrylonitrile, polyesters, polyurethanes, poly(meth)acrylates, polyethylenes, polystyrenes, and any combinations and mixtures thereof. The core preferably comprises a liquid selected from organic liquids such as pentane, hexane, heptane, octane, nonane and decane as well as their halogenated derivates. and gases selected from methane, propane, nitrogen, noble gases, and any combinations thereof. The expanded hollow organic microspheres preferably exhibit a density in the range of from about 0.001 to about 0.1 g/cc (grams per cubic centimeter), preferably from about 0.002 to 0.08 g/cc, and more preferably from about 0.003 to about 0.06 g/cc. The expanded hollow organic microspheres exhibit a particle size mode (peak) in the range of from about 10 micrometers to about 300 micrometers, preferably from about 20 to about 250 micrometers, and more preferably in the range from about 30 to about 200 micrometers.

[0069] Furthermore, it was found to be advantageous to disperse the hollow microspheres within a mixture during the production process of the thermal barrier article according to the present invention. This has at least one advantage of improved processability of the particles and/or improved process safety as it is known that small organic particles may form a combustible mixture with air. Preferably, the mixture used to disperse the hollow microspheres is selected from inorganic materials, organic resins, inorganic liquids such as water, organic liquids, preferably selected from oils such as mineral oils, natural oils and synthetic oils, alcohols such as polyvinylalcohol and any combinations and mixtures thereof. The organic resins may be selected from epoxy resins, polyester resins, polyurethane resins, polycarbonate resins, poly ether resins, ethylene vinyl acetate resins, and any combinations thereof.

[0070] In some embodiments, the foam particles are selected from silicone foam particles, polyurethane foam particles, rubber foam particles, polyolefin foam particles (such as polypropylene), polystyrene foam particles, thermoset foam particles, polyethersulfone foam particles, or other organic foam particles, and mixtures thereof.

[0071] In some embodiments, the average particle size of the compressible organic particles is at least 1 pm, 5 pm, 10 pm, 20 pm, 50 pm, 75 pm, or even 100 pm. In some embodiments, the average particle size of the compressible organic particles is at most 25 pm, 50 pm, 100 pm, 200 pm, 250 pm, 400 pm, 500 pm, 750 pm, 1 mm, 2mm, 5 mm, or even 10 mm. The average particle size may be measured using techniques known in the art including laser diffraction, optical microscopy, or sieves. In some embodiments, the particle size of the compressible organic particles is up to 10 mm and may be from 1 pm to 10 mm, or from 10 pm to 10 mm, or from 100 pm to 10 mm, or from 1 mm to 10 mm, as measured by sieve analysis. In some embodiments, the median particle size (dso) of the compressible organic particles is from 1 pm to up to 500 pm, or from 1 pm to up to 250 pm. The median particle size (dso) may be measured by laser diffraction.

[0072] The shape of the compressible organic particles may be spherical or irregular or any other shape.

[0073] The layer of nonwoven fibrous thermal insulation may comprise the compressible organic particles in an amount of from 1 to 50 percent by weight, or from 3 to 30 percent by weight, or from 3 to 25 percent by weight, or from 3 to 20 percent by weight, based on the total weight of the nonwoven fibrous thermal insulation. In some embodiments, the layer of nonwoven fibrous thermal insulation comprises at least 1%. 2%, 3%, 5%, 10%, 15%, or even 20% by weight of the compressible organic particles. In some embodiments, the layer of nonwoven fibrous thermal insulation comprises at most 50%, 40%, 35%, 30%. 25%, 20%. 15%, or even 10% by weight of the compressible organic particles. Generally, the amount of compressible organic particles used in the nonwoven fibrous thermal insulation layer will be balanced between providing the desired compression performance while minimizing the flammability and/or thermal conductivity of the article. In some embodiments, the layer of nonwoven fibrous thermal insulation may comprise the compressible organic particles in an amount of from 3 to 20 percent by weight, based on the total weight of the nonwoven fibrous thermal insulation.

[0074] The compressible organic particles refer to organic particles, which may be compressible to a certain extent (i.e., to a smaller size) and ideally return to their original size when the compressing force is removed. It is thought that this behavior yields the elasticity of the thermal barrier article. That is, if a compressing force onto one of the major surfaces compresses the articles to a compressed or thinner state, it will return (ideally) to its original thickness or to a thickness close to its original thickness.

[0075] The pressure exhibited by the thermal barrier disclosed herein is lower than the pressure exhibited by a thermal barrier comprising a layer of a nonwoven fibrous thermal insulation of the same composition but without the addition of the compressible organic particles (assuming the same thickness and/or basis weight the samples). The pressure exhibited by the thermal barrier disclosed herein in an installed (i.e.. compressed) condition is at least 10%. or at least 15%, or at least 20%, or at least 25%. or at least 30%, or at least 35%, or at least 40%, or at least 45%, or at least 50% lower than the pressure exhibited by a thermal barrier comprising a layer of a nonwoven fibrous thermal insulation of the same composition but without the addition of the compressible organic particles. The pressure exhibited by the thermal barrier disclosed herein is up to 60% lower than the pressure exhibited by a thermal barrier comprising a layer of a nonwoven fibrous thermal insulation of the same composition but without the addition of the compressible organic particles. This decrease in pressure exhibited by the thermal barrier can be observed when both the pressure exhibited by the thermal barrier disclosed herein and by a thermal barrier without the addition of the compressible organic particles are measured at the same relative axial compression and the same sample thickness for tire uncompressed and compressed thermal barriers, i.e., when both the pressure exhibited by the thermal barrier disclosed herein and by a thermal barrier without the addition of the compressible organic particles are measured at the same gap.

[0076] In some embodiments, the thermal barrier article of the present disclosure can be tested for its initial compression performance, wherein the layer of nonwoven fibrous thermal insulation is placed between two platens and a load is applied and the relaxed pressures were measured based on a given gap size. In some embodiments, the addition of the compressible organic particles decreases the pressure relative to a control (i.e., the same material without the compressible organic particles) by at least 20%, 25%, 30%. 35%. or even 40% depending on the gap size used, for example, such as described Compression Performance Test Method 1.

[0077] Typically in use, the thermal barrier articles are exposed to repeated cycling of loads. For example, modem lithium ion batteries or battery cells tend to “breathe” upon loading and unloading, i.e., the battery cells grow in their volume upon loading and shrink upon unloading. During a lifetime of battery, the cells undergo a multitude of loading and unloading cycles, and this may also alter the volume of the battery over its lifetime. That is, a battery cell may shrink or grow in volume over its lifetime. The elastic property of the article according to the present invention is advantageous since the article is oftentimes disposed betw een battery cells and needs to follow- the size of the cells during operation, i.e. during loading and unloading. With the elastic property as described herein, the article according to the present invention is able to follow the size of the cells over its lifetime without any deterioration of its other advantageous properties, in particular its abilities in the occurrence of a thermal runaway event.

[0078] The swelling and shrinking of a battery cell and its influence on a thermal barrier as described herein may be simulated in a cyclic compression test such as those described in the method section.

[0079] In one instance, a cyclic test is applied such as described in Compression Performance Test Method 2, the thermal barreir article is repeatedly compressed and released and the low est pressure is reported. The pressure upon compression are reported as P max, while the pressures after release are reported as P min. It was formd that, in some embodiments, thermal barrier articles having minimum pressure peak, P min. above certain levels are particularly advantageous for the applications as described herein. Accordingly, in some embodiments, it is preferred that the thermal barriers according to the present invention exhibit a minimum pressure peak, P min. determined according to the test described in the experimental section of at least 20 kPa, 25 kPa. 30 kPa, 40 kPa, or even 50 kPa. In some embodiments, the thermal barreir article according to the present disclsoure have a percent recovery (i.e., P min I pressure applied) of at least 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, or even 80%.

[0080] When cycling the thermal barrier articles, the begiiming-of-life pressure (e.g., pressure at cycle 1) and end-of life pressure (e.g., pressure at cycle 1000) can be examined. In some embodiments, when the thermal barrier articles of the present disclsoure are tested, they have a delta end-of-life of less than 1000 kPa, 750 kPa, 500 kPa, or even 400 kPa. Wherein the delta end-of-life is determined by subtracting the P min from P max at the last cycle. Generally, it is advanatgeous to have a low delta end-of-life. however a delta end-of-life should be at least above 50 kPa.

[0081] In another instance, a cyclic test is applied such as described in Compression Perfonnance Test Method 3. As mentioned above, thermal barrier materials need to meet not only the presesures exerted at the start of the compression testing (i.e.. begining-of-life) but also meet required pressure at the end of the compression testing (i.e.. end-of-life). In reporting resulting for this test method, the begining-of-life is reported as the P min for the first testing cycle and the end-of life is reported as the P max at the last testing cycle. In some embodiments, the thermal barriers of the present disclosure have an improved beginning of life and end of life performance. For example, in some embodiments, the thermal barrier articles of the present disclosure have a beginning-of-life of at least 25, 30, 40. 50. 75, 100, 500, or even 100 kPa. In some embodiments, the thermal barrier articles of the present disclosure the end-of-life is at most 2000. 1800, or even 1600 kPa.

[0082] The thermal barrier exhibits a pressure in an installed (i.e., compressed) condition on an adjacent battery' cell. The compressible organic particles that are comprised in the layer of nonwoven fibrous thermal insulation of the thermal barrier disclosed herein have the function of affecting compression performance of the thermal barrier and may also be referred to as “compression performance affecting particles”. This means that the thermal barrier is more compressible due to the addition of the compressible organic particles, or, in other words, the thermal barrier can be compressed to a higher extent with less pressure exerted on the thermal barrier. This also means that the pressure exerted by the thermal barrier on an adjacent battery cell in an installed (i.e., compressed) condition is decreased as compared to a thermal barrier not comprising the compressible organic particles. Due to the improved compressibility, the thermal barrier is able to meet both the beginning-of-life and end-of-life compression requirements when placed between the battery cells.

[0083] The thermal barrier materials of the present disclosure should be thermally stable at temperatures of thermal runaway conditions thus, in some embodiments, the amount of organic material present in the thermal barrier may be less than 50, 45, 40, 35. 30, 25, 20, or even 15 wt.%.

[0084] Generally, to be a sufficient thermal barrier material, the nonwoven fibrous thermal insulation of the present disclosure should pass a Flammability test. For example, UL-94 standard (active standard at the time of this filing), the Standard for safety of Flammability of Plastic Materials for Parts in Devices and Appliances testing determines a material’s tendency to either extinguish or spread the flame once the specimen has been ignited. The UL-94 standard is harmonized with IEC 60707, 60695-11-10 and 60695- 11-20 and ISO 9772 and 9773. Breifly, a 75 mm x 150 mm sample is exposed to a 2 cm, 50W tirrel burner flame ignition source. The test sample is placed vertically above the flame with the test flame impinging on the bottom of the sample. For each sample, the time to extinguish is measured and V ratings are assigned. The V ratings are a measure to extinguish along with the sample not burning to the top clamp or dripping molten material which would ignite a cotton indicator. The ratings are shown in Table 1 below. Table 1: UL94 classification (V rating)

[0085] The layer of nonwoven fibrous thermal insulation may have an installed (i.e., compressed) thickness in the range of from 0.5 mm up to 20.0 mm. In particular, the installed (i.e.. compressed) thickness may be in the range of from 0.5 mm up to 2.5 mm, where the lower limit can be about 0.5 mm, 0.6 mm. 0.7 mm, 0.8 mm. 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm. 1.4 mm, or 1.5 mm, and the upper limit can be about 1.6 mm, 1.7 mm, 1.8 mm. 1.9 mm, 2.0 mm, 2.1 mm. 2.2 mm, 2.3 mm, 2.4 mm. or 2.5 mm. In some applications, the installed thickness may be in the range of from 5 mm up to 20 mm, where the lower limit can be about 5 mm, 6 mm, 7 mm, 8 mm. 9 mm, 10 mm, 11 mm, or 12 mm, and the upper limit can be about 13 mm. 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, or 20 mm. In some applications, the installed thickness may be in the range of from 10 mm up to 20 mm, where the lower limit can be about 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, or 15 mm, and the upper limit can be about 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, or 20 mm. In some applications, the installed thickness may even be as high as about 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, 4.0 mm, 4.1 mm, 4.2 mm, 4.3 mm, 4.4 mm, 4.5 mm, 4.6 mm, 4.7 mm, 4.8 mm, 4.9 mm, or 5.0 mm. The installed thickness of the layer of nonwoven fibrous thermal insulation is almost always less than its uninstalled (i.e., uncompressed) thickness. The perfonnance of the thermal barrier is measured when it is in its installed (i.e.. compressed) condition.

[0086] The layer of nonwoven fibrous thermal insulation may have an uninstalled (i.e., uncompressed) thickness in the range of from 1.0 mm to up to 8.0 mm. where the lower limit can be about 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm. 1.5 mm. 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm. 2.0 mm. 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm. 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm. 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm. or 3.5 mm. and the upper limit can be about 4.0 mm, 4.1 mm. 4.2 mm. 4.3 mm. 4.4 mm, 4.5 mm, 4.6 mm, 4.7 mm, 4.8 mm, 4.9 mm. 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, 7.0 mm. 7.5 mm, or 8.0 mm. The uncompressed thickness of the layer of nonwoven fibrous thermal insulation is always greater than its installed thickness. [0087] The layer of nonwoven fibrous thermal insulation has a weight per square meter in the range of from 100 g/m² up to 2000 g/m². Depending on the composition of the thermal barrier, it can be desirable for the weight per square meter to be in the range of from about 100 g/m² (e.g.,150 g/m², 200 g/m², or even 250 g/m²) to about 400 g/m² (e.g., 300 g/m², 350 g/m²) for a gap between adjacent battery cells in the range of from about 0.75 mm up to about 1.25 mm. Depending on the composition of the thermal barrier, it can also be desirable for the weight per square meter to be in the range of from about 300 g/m² up to about 550 g/m² for a gap between adjacent battery cells in the range of from about 0.75 mm up to about 2.5 mm. For gaps between adjacent battery' cells in the range of from about 2.5 mm up to 8.0 mm, it can be desirable for the weight per square meter to be in the range of from about 600 g/m² up to about 2000 g/m² (e.g.. 650 g/m², 700 g/m², 750 g/m², 800 g/m², 900 g/m², 950 g/m², 1000 g/m², 1050 g/m², 1100 g/m², 1150 g/m², 1200 g/m², 1250 g/m², 1300 g/m², 1350 g/m². 1400 g/m², 1450 g/m², 1500 g/m², 1600 g/m², 1700 g/m², 1750 g/m², 1800 g/m², 1900 g/m², or 2000 g/m²).

[0088] The thermal barrier disclosed herein may optionally further comprise an organic encapsulation layer encapsulating the layer of nonwoven fibrous thermal insulation. The optional organic encapsulation layer may be a polymeric layer or a paper layer. The organic encapsulation layer may be. e.g., one layer or multiple opposing sandwiching layers, with each layer being in the form of a film, coating, organic fibrous nonwoven or woven fabric. The organic encapsulation layer may enclose or otherwise encapsulate all of, a majority of or a portion of at least one or both major faces and preferably also all of, a majority of or a portion of the peripheral edge of the layer of nonwoven fibrous thermal insulation so as to prevent or significantly reduce the shedding or loss of fibers or particles from the encapsulated layer of nonwoven fibrous thermal insulation.

[0089] The thermal barrier disclosed herein may optionally further comprise an inorganic encapsulation layer encapsulating the layer of nonwoven fibrous thermal insulation. The optional inorganic encapsulation layer may be. e.g., glass fiber woven fabric of 25 - 80 g/m². The inorganic encapsulation layer may be, e.g.. one layer or multiple opposing sandwiching layers, with each layer being in the form of an inorganic coating or fibrous nonwoven or woven fabric. The inorganic encapsulation layer may enclose or otherwise encapsulate all of, a majority of or a portion of at least one or both major faces and preferably also all of, a majority of or a portion of the peripheral edge of the layer of nonwoven fibrous thermal insulation so as to prevent or significantly reduce the shedding or loss of fibers or particles from the encapsulated layer of nonwoven fibrous thermal insulation.

[0090] The reduction of inorganic fiber or particle shedding is significant, when the number of inorganic fibers or particles lost is less than 10%, 5% or 1% by weight percent of the original fiber or particle content of the layer of nonwoven fibrous thermal insulation. The thinner the organic encapsulation layer (i.e., the lower the organic content of tire barrier) the better the hot/cold test results.

[0091] The thennal barrier may be provided as a thermal barrier assembly comprising a plurality of the thennal barriers as disclosed herein, wherein the plurality of thermal barriers are provided (a) in a container (e.g., a cardboard or other box) in the form of a stack, (b) disposed end-to-end in series, with one major face of each thermal barrier being adhered onto a major adhesive surface of a length of single-sided or double-sided adhesive tape (when a double-sided adhesive tape is used, the opposite major adhesive surface of the tape can be protected by a release liner), or (c) disposed end-to-end in series in the form of a tape, with the one or more layers of nonwoven fibrous thermal insulation of each thermal barrier being disposed end-to-end and sandwiched or otherwise encapsulated between two opposing lengths of organic (e g., polymeric) encapsulation layers (e.g., in the form of two opposing films, coatings, fibrous fabrics, etc.).

[0092] Further disclosed herein is a method of making the thermal barrier disclosed herein, the method comprising: forming a layer of nonwoven fibrous thermal insulation using a wet-laid process or dry -laid process; providing a plurality of thermally insulative inorganic particles; disposing the plurality of thermally insulative inorganic particles so as to be evenly or uniformly distributed throughout or within the layer of nonwoven fibrous thermal insulation; providing a plurality of compressible organic particles; and disposing the plurality of compressible organic particles so as to be evenly or uniformly distributed throughout or within the layer of nonwoven fibrous thennal insulation.

[0093] The process step of forming a layer of nonwoven fibrous thermal insulation using a wet-laid process or dry -laid process comprising providing inorganic fibers; providing a binder; and mixing the inorganic fibers and the binder.

[0094] The inorganic fibers, the binder, and the plurality of particles as described above for the thermal barrier may be used for making the thermal barrier disclosed herein.

[0095] Referring to Fig. 1. a layer of a nonwoven fibrous thermal insulation 10 is shown comprising an inorganic fiber matrix, a binder, and the plurality of particles. Optionally, the layer of a nonwoven fibrous thermal insulation 10 is encapsulated with an organic or inorganic layer 12.

[0096] Referring to Fig. 2, an exemplary battery cell module 20 includes a plurality of battery cells 22 and a plurality of thermal barriers 24. Each thermal barrier 24 can be in the form of one or more layers of a nonwoven fibrous thermal insulation 10, with or without an encapsulation layer 12, and that can be made from the exemplary materials described herein. A thermal barrier 24 can be disposed between adjacent battery cells 22, between groups of cells 22, or both, at one or more locations throughout the batter cell module 20. Typically, the battery cell module 20 rests above a cooling plate 26 and a tray 28.

[0097] Referring to Fig. 3. an exemplary battery pack 30 includes a plurality of battery cell modules 20, which may each have its own cooling plate 26 and tray 28 or all of the modules 20 may share the same cooling plate 26 and tray 28. A thermal barrier 24, formed from the exemplary materials described herein, can be disposed betw een one or more or all adjacent battery cell modules 20, on the top of one or more or all of the battery cell modules 20 (see reference number 24’). or any combination of both. A single or multiple thermal barriers 24 may also be dimensioned so as to cover the tops of all of the batten cell modules 20.

[0098] Referring to Fig. 4, an exemplary thermal barrier 24 includes one or more fiber matrix layers (not shown) encapsulated with an layer 12 that covers both sides and the peripheral edge of the one or more layers of a nonwoven fibrous thermal insulation. In one embodiment, the major opposite faces of the encapsulating layer 12 are coated with an adhesive (e.g., a pressure sensitive adhesive) protected by corresponding release liners 14 and 16. It is preferable for the encapsulating layer 12 to include one or more outlets or openings 18 (e.g., in the form of a notch) that allows air (e.g., hot air) or other gases to escape from inside the encapsulation layer 12 to swell and expand like a balloon, e g., when the air trapped in the encapsulation layer 12 is heated to an elevated temperature (e.g., when the temperature of one or more of the adjacent battery cells 20 increases).

[0099] Referring to Fig. 5, a conventional dry-laid manufacturing equipment and processes can be used to manufacture thermal barriers as disclosed herein. Examples of such equipment and processes can be found described in U.S. Pat. Nos. 9,580.848 (Henderson et al.), 9.475.034 (Vincent et al.), 7,491,354 (Anderson), and 6.808.664 (Falk et al.). Such equipment can include a chamber or forming box 40 with multiple feeder inlets, including an inlet 42 for feeding any desired combination of matrix fibers (inorganic fibers) and binder into the box 40. and multiple inlets 44, 44’ and 44” for feeding the thermally insulative particles and the compressible organic particles into the box 40. After the fibers are combined and mixed together with the other ingredients, the resulting nonwoven fibrous material 45 is deposited onto a belt 46 that conveys the material 45 into, through and out of a baking oven 47 where the binder is cured at least so that the fibrous material 45 can be further processed. The resulting cured nonwoven fibrous material 45 ’ is then die-cut, laser-cut, water-jet cut, or otherwise processed into individual nonwoven fiber layers 10 (not shown), which are then processed at an encapsulation station 48, e.g.. by having a polymeric film 12 (not shown) laminated to opposite sides of a single layer 10 or a stack of two or more layers 10. An optional hot melt adhesive or pressure sensitive adhesive can be applied to one or both sides of the encapsulate 12 at corresponding spray stations 49 and 49’ . A protective release liner (not shown) can be subsequently applied to each adhesive surface.

[00100] An example of a “wet laid’’ process that may be used to manufacture thermal barriers as disclosed herein is described in the Examples of U.S. Pat. No. 6,458,418, which is incorporated herein by reference in its entirety. In such a wet laid process, a thermal barrier can be made using at least one dilute (desirably, not over 5 percent solids by weight) aqueous slurry containing inorganic fibers, binder and thermally insulative particles and the compressible organic particles, by depositing the aqueous slurry onto a permeable substrate, such as a screen or a “wire” of a paper making machine, partially dewatering the slurry by gravity and/or vacuum and then pressing to increase the density (e.g., with pressure rollers). The thennal barrier is then fully dried with heated rollers. [00101] Further disclosed herein is a batten cell module for an electric vehicle, the batten cell module comprising: a plurality of battery cells disposed in a housing; and a plurality of thermal barriers as disclosed herein, wherein one thermal barrier is disposed betw een each pair of adjacent battery’ cells.

[00102] A plurality of battery cell modules may be included in a battery pack.

[00103] The following items will serve to illustrate preferred embodiments of the present invention. It is understood, however, that they serve illustrative purposes and are not to be construed in a manner that would unduly limit the scope of this invention.

[00104] Item 1 : a thermal barrier article, comprising

(i) at least one layer of a nonwoven fibrous thermal insulation comprising

(a) a fiber matrix of inorganic fibers;

(b) a plurality of thermally insulative inorganic particles dispersed within the fiber matrix;

(c) a binder dispersed within the fiber matrix so as to hold together the fiber matrix; and

(d) a plurality of compressible organic particles dispersed within the fiber matrix; and

(ii) optionally, at least one organic encapsulation layer encapsulating the at least one layer of nonwoven fibrous thermal insulation.

[00105] Item 2: The thermal barrier article according to item 1, wherein the addition of the compressible organic particles decreases a pressure observed by the thermal barrier article by at least 20% compared to the same thermal barrier article without compressible organic particles.

[00106] Item 3: The thermal barrier article according to item 1 or item 2, wherein the thermal barrier exhibits a minimum pressure peak P(min) determined according to the test described in the experimental section of at least 25 kPa, preferably of at least 30 kPa, and more preferably at least 40 kPa, even more preferably at least 50 kPa per Compression Performance Test 2.

[00107] Item 4: The thermal barrier article according to any one of the preceding items, wherein the at least one layer of nonwoven fibrous thermal insulation contains an amount of thermally insulative inorganic particles in the range of from as low as about 10% up to as high as about 60 % by weight of the layer of nonwoven fibrous thermal insulation.

[00108] Item 5 : The thermal barrier according to any one of the preceding items, wherein the at least one layer of nonwoven fibrous thermal insulation contains an amount of binder in the range of from as low as about 2.5% up to as high as about 10.0%, by weight of the layer of nonwoven fibrous thermal insulation. [00109] Item 6: The thermal barrier according to any one of the preceding items, wherein the at least one layer of nonwoven fibrous thermal insulation contains an amount of compressible organic particles in the range of from as low as about 0.5% up to as high as about 20%, preferably from about 0.8% up to as high as about 15%. and more preferably from about 1% up to as high as about 10%, by weight of the at least one layer of nonwoven fibrous thermal insulation.

[00110] Item 7: The thermal barrier according to any one of the preceding items, wherein the compressible organic particles are selected from expanded microspheres, rubber particles, foam particles, silicone particles, polyurethane particles, styrenic block copolymer particles, and any combinations and mixtures thereof.

[00111] Item 8: The thermal barrier according to item 7. wherein the compressible organic particles are selected from hollow organic microspheres, preferably from expandable hollow organic microspheres and expanded hollow organic microspheres.

[00112] Item 9: The thermal barrier according to item 8, wherein the hollow organic microspheres comprise a polymeric shell and a core comprising a liquid or gas.

[00113] Item 10: The thermal barrier according to item 9, wherein the polymeric shell contains a thermoplastic shell composition comprising compounds selected from acrylonitrile, methacrylonitrile, polyesters, polyurethanes. poly(meth)acrylates, polyethylenes, polystyrenes, and any combinations and mixtures thereof.

[00114] Item 11: The thermal barrier according to item 9 or item 10, wherein the core comprises a liquid selected from organic liquids such as pentane, hexane, heptane, octane, nonane and decane as well as their halogenated derivates, and gases selected from methane, propane, nitrogen, noble gases, and any combinations thereof.

[00115] Item 12: The thermal barrier according to item 7, wherein the foam particles include silicone foam particles, polyurethane foam particles, rubber foam particles, polyolefin foam particles (such as polypropylene), polystyrene foam particles, thermoset foam particles, polyethersulfone foam particles, or other organic foam particles, or mixtures thereof.

[00116] Item 13: The thermal barrier according to any one of the preceding items, wherein the compressible organic particles are dispersed within a matrix selected from inorganic materials, organic resins, inorganic liquids such as water, organic liquids, preferably selected from oils such as mineral oils, natural oils and synthetic oils, alcohols such as polyvinylalcohol and any combinations and mixtures thereof.

[00117] Item 14: The thermal barrier according to item 13, wherein the organic resins are selected from epoxy resins, polyester resins, polyurethane resins, polycarbonate resins, polyether resins, ethylene vinyl acetate resins, and any combinations thereof. [00118] Item 15: The thermal barrier according to any one of the preceding items, wherein the thermal barrier exhibits a beginning-of-life of at least 25 kPa and an end-of-life of at most 2000 kPa.

[00119] Item 16: The thermal barrier according to any one of the preceding items, wherein the layer of nonwoven fibrous thermal insulation has an installed thickness in the range of from about 0.5 mm up to less than 20 mm, preferably from about 1 mm up to less than about 17 mm, more preferably from about 2 mm up to less than about 15 mm.

[00120] Item 17: The thermal barrier according to any one of the preceding items, wherein the layer of nonwoven fibrous thermal insulation has a basis weight in the range of from as low as about 100 g/square meter and up to as high as about 5000 g/square meter, preferably from about 200 g/square meter and up to as high as about 4000 g/square meter, and more preferably from about 300 g/square meter and up to as high as about 3000 g/square meter.

[00121] Item 18: The thermal barrier according to any one of the preceding items, wherein the layer of nonwoven fibrous thermal insulation has an uncompressed basis weight in the range of from about 100 g/square meter up to about 3000 g/square meter, preferably from about 200 g/square meter up to about 2500 g/square meter, and more preferably from about 300 g/square meter up to about 2000 g/square meter. [00122] Item 19: The thermal barrier according to any one of the preceding items, wherein the thermally insulative inorganic particles comprise particles of one or any combination of the materials selected from the group consisting of inorganic aerogel, xerogel, hollow or porous ceramic microspheres, unexpanded vermiculite, irreversibly or permanently expanded vermiculite, fumed silica, otherwise porous silica, irreversibly or permanently expanded or unexpanded perlite, pumicite, irreversibly or permanently expanded clay, diatomaceous earth, titania, and zirconia.

[00123] Item 20: The thermal barrier according to any one of the preceding items, wherein the layer of nonwoven fibrous thermal insulation is encapsulated by the organic encapsulation la er.

[00124] Item 21: The thennal barrier according to item 20, wherein the organic encapsulation layer further comprises a nonwoven layer.

[00125] Item 22: The thermal barrier according to any one of the preceding items, wherein the organic encapsulation layer has at least one vent hole formed therethrough that is located and sized to allow gas contained within the thermal barrier to escape from the organic encapsulation, such that the structural integrity of the organic encapsulation layer is kept intact, during a thermal runaway event.

[00126] Item 23: The thermal barrier according to any one of items 20 to 22, wherein the thermal barrier has a top edge, a bottom edge and opposite side edges, and the at least one vent orifice such as a slit or hole is located along the periphery' of one or both opposite side edges. Each layer may have at least one vent hole formed therethrough that is located and sized to allow expanding gas (e.g., air) contained within the thennal barrier to escape from the organic encapsulation, such that the structural integrity of the organic encapsulation layer is kept intact (i.e., the layer of nonwoven fibrous thermal insulation remains completely, mostly or at least significantly encapsulated by the organic encapsulation layer), when the thermal barrier is compressed during the assembly of the battery cell module (e.g., a stack of battery cells) or when the thermal barrier heats up (e.g., during the normal operation or overheating of the adjacent battery cells). Each vent hole can be in the shape of a rectangle, circle, oval or any other shape desired or combination thereof. One or more or each vent hole can be in the form of a notch that projects from a side edge of the encapsulation towards the center of the thermal barrier Alternatively, one or more or each vent hole can be formed interior of the side edge of the encapsulation and adjacent to the non woven thermal insulation In addition, one or more or each vent hole can be formed through the encapsulation layer on only one side of the nonwoven fibrous thermal insulation. It can also be desirable for each vent hole to be in the form of a plurality of small perforation, that arc clustered together (e.g., like a screen, sieve or colander) to provide the desired exit opening area. The thermal barrier has a top edge, a bottom edge and opposite side edges, and the at least one vent hole may be located along the periphery of one or both opposite side edges.

[00127] Item 24: The thermal barrier according to any one of items 22 to 23 wherein the at least one vent hole may provide an exit opening through the organic encapsulation layer having an opening area in the range of from about 2 mm² up to about 15 mm². It is contemplated that any particular area within this range, or any narrower range within this range, could be desirable.

[00128] Item 25: The thermal barrier according to item 24. wherein the at least one vent orifice provides an exit opening through the organic encapsulation layer having an opening area in the range of from about 2 square mm up to about 15 square mm.

[00129] Item 26: The thermal barrier according to any one of items 22 to 25, wherein the organic encapsulation layer comprises at least one polymeric layer.

[00130] Item 27. The thermal barrier according to item 26, wherein the at least one polymeric layer is heat-shrunk, or wherein the at least one polymeric layer is wrapped around the thermal insulation layer in two directions at an angle and comprises at least one sealed area, or wherein the at least one polymeric layer is wrapped around the at least one thermal insulation layer in one direction and comprises at least two sealed areas.

[00131] Item 28: The thermal barrier according to any one of items 26 to 27, wherein the at least one polymeric film comprises at least one polymeric material selected from polyolefins, polyvinylchloride, ethylene-vinyl acetate copolymer, preferably from polyolefins.

[00132] Item 29: The thermal barrier according to item 27, wherein the at least one sealed area is a heat-sealed area, an ultrasonically welded area, or an adhesively bonded seal.

[00133] Item 30: The thermal barrier according to item 1 , wherein the at least one polymer layer is wound in a horizontal form fill seal procedure (HFFS) or in a vertical form fill seal procedure (VFFS). preferably in a vertical form fill seal procedure (VFFS). [00134] Item 31 : The thermal barrier according to any one of the preceding items, wherein the layer of nonwoven fibrous thermal insulation passes at least the V-2 level of the UL94 Flammability⁷ Test.

[00135] Item 32: A battery⁷ cell module for an electric vehicle, said battery⁷ cell module comprising:

(A) a plurality⁷ of battery cells disposed in a housing; and

(B) a plurality of thermal barriers according to any one of items 1 to 31; wherein the battery⁷ cells a lined up in a row, with one thermal barriers being disposed between each pair of adjacent battery cells.

[00136] Item 33: The battery cell module according to item 32, wherein the battery⁷ cell module is a lithium ion battery cell module.

[00137] Item 34: A method of making the thermal barrier according to any one of items 1 to 31, wherein the method comprises forming the layer of nonwoven fibrous thermal insulation using a wet-laid process or dry-laid process.

[00138] Item 35: The method according to item 34, further comprising: providing thermally insulative inorganic particles that are made completely of mostly of or at least comprise unexpanded intumescent particles (e.g., unexpanded vermiculite particles or unexpanded perlite particles); providing compressible organic particles that are selected from expanded microspheres, rubber particles, foam particles, silicone particles, polyurethane particles, styrenic block copolymer particles, and any combinations and mixtures thereof; disposing the thermally insulative inorganic particles and the compressible organic particles so as to be evenly or uniformly distributed throughout or within the layer of nonwoven fibrous thermal insulation; and heating the unexpanded intumescent particles and the compressible organic particles to a temperature and for a time that causes the unexpanded intumescent particles and optionally , the compressible organic particles, to irreversibly or permanently expand, wherein the heating occurs before or after the thermally insulative inorganic particles and/or the compressible organic particles are disposed within the layer of nonwoven fibrous thermal insulation.

[00139] Item 36: The method according to item 35, wherein die heating causes the unexpanded intumescent particles and optionally, the compressible organic particles such as the expandable hollow microspheres to irreversibly or permanently expand in the range of from at least about 10%, 20%, 30%, 40%, 50%, 60%. 70%, 80% or 90% and up to 100% of their expandability⁷.

[00140] Item 37: Use of the thermal barrier according to any one of items 1 to 31 for at least slowing down propagation of thermal runaway events in batteries.

[00141] Item 38: Use according to item 37, wherein the batteries are lithium ion batteries.

[00142] Item 39: Use according to item 38, wherein the lithium ion batteries are comprised in a vehicle such as car, bus, train, ship, or aircraft.

[00143] Item 40: Use of the thermal barrier according to any one of items 1 to 31 in the manufacture of lithium ion batteries. EXAMPLES

[00144] Unless otherwise noted or readily apparent from the context, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. [00145] These abbreviations arc used in the following examples: cm = centimeter, g = grams, gsm

= grams per square meter, °C = degrees Celsius, in = inch. Ibf = pound force, kgf = kilogram force, kPa = kiloPascal, m = meter, min = minute, pm =micrometers, mm = millimeter, MPa = megaPascal. N = Newton, sec = second, and W = watt.

Materials table

[00146] Test methods

[00147] Compression Performance Test Method 1:

[00148] The samples were tested for compression performance by placing a two-inch (50.8-mm) diameter sample having a height of 8 mm between two platens on a load-frame (MTS Alliance RT/50 load frame). The top platen was slowly moved down until the force reached 10N. This was marked as the free height of the sample. The top platen was then moved down at a speed of 25 mm/min till the gap between the platens was 5.0 mm. The pressure was recorded and noted as Peak Pressure at 5.0 mm. The sample was held at this gap for 300 sec. The pressure was recorded at the end of 300 sec and this pressure was noted as Relaxed Pressure at 5.0 mm. The top platen was then moved down further to 4.5 mm and the measurement of Peak Pressure and Relaxed pressure as explained above was repeated. Such pressures were recorded for the following gaps (in mm): 5.0, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, 1.5 and 1.0. The relaxed pressures were plotted as a function of the gap.

[00149] Compression Performance Test Method 2 (Cyclic)

[00150] The samples were tested for compression performance using a tensile tester (available from ZwickRoell GmbH & Co. KG. Ulm, Germany) in compression mode. The testing sample had a diameter of 50.8 mm and a thickness more than 3 millimeters. The test was performed at about 23°C. The upper plate of the tester was moved with a speed of 25 mm/min until a maximum force of 300 kPa was reached. After allowing the gap to relax for 15 sec at 300 kPa, the gap was held in the same position for 300 sec. The starting thickness defined in this way applies as sample thickness. In the following, the upper plate moved 1000 cycles up and down holding the gap for 5 sec at every maximum and minimum peak of each cycle.

[00151] The first gap cycle started with an amplitude of 12.5 % of the starting gap at a speed of 1 mm/min for a full load/unload cycle. From cycle 1 to cycle 1000 the amplitude was incrementally reduced to 12.5 % I 2 = 6.25 %.

[00152] Simulating battery Li-ion cells at a state of charge (SOC) of 30 % at module assembly, the gap closing was 70 % of the amplitude to reach a fully loaded cell at 100 % SOC. In the following step the upper plate moved up and stopped at a full breathing amplitude at 0 % SOC. Consequently, the 2nd gap started at a gap bigger than the starting thickness.

[00153] Additionally, with every cycle the open gap at 0 % SOC and the closed gap at 100 % SOC was incrementally reduced by 25% reaching 75% of the starting gap cycle 1000. [00154] The compression force (in kPa) was recorded for each maximum (max) and minimum (min) peak of each cycle. The lowest pressure of the entire test was reported as minimum pressure peak P min.

[00155] In some embodiments, the % recover}' is reported, which was calculated as (P min/300kPa)x 100. In some embodiments, also reported was the P max and P min at the cycle 1000, which is desingationed as the end of life (EOL). P min was substracted from P max and reported as delta EOL. [00156] Compression Performance Test Method 3 (Cyclic)

[00157] The samples were tested for compression performance by placing a four inch by four inch (101.6-mm) square sample having a height of up-to 1 inch (25.4 mm) between two platens on a load-frame (model 5969 from Instron, Norwood, MA). The top platen was moved down till the gap between surfaces reached 3.5 mm. This was marked as the starting height of the sample and this configuration was held for one hour to allow stresses to relax. The top platen was then moved down 0.5 mm at a speed of 1 pm/s till the gap between the platens was 3 mm, and this position was again held for 1 hour. The top platen was then moved up 0.4 mm at a speed of 1 pm/s till the gap was 3.4 mm. and this configuration was again held for 1 hour. The compression-decompression cycle of moving down 0.5 mm, holding for one hour, moving up 0.4 mm. holding for one hour was repeated until either the pressure registered 3 MPa, or the gap configuration was 1.6 mm. whichever happened first. During the entire test, the resulting compressive pressure was recorded by the pressure transducer of the equipment. The performance of the sample is then measured in terms of minimum pressure detected (named as beginning-of-life or BOL), and, when applicable, the pressure measured when the sample gap was 1.8 mm (named as end-of-life or EOL).

[00158] Method for determining base weight:

[00159] Two-inches (50.8 mm) diameter samples having a height of 8 mm were weighed on a weighing balance and the weight was divided by the area of the sample. The base weight of all samples was in the range of 1050 to 1370 g/m².

[00160] The general method for preparing thermal barrier:

[00161] Combinations of staple fibers by weight percent (as identified in the tables below) were weighed and premixed by hand before placing on top of a feeding belt. The fiber material was processed (i.e.. fed from the top) through an air-laid processer, like that disclosed in U.S. Pat. No. 7,491,354, where the fibers were opened and dispersed into an air stream, then collected on a screen belt. Details of such airlaid (or dry -laid) processing apparatus and methods of using such apparatus in forming air-laid webs can be found described in U.S. Pat. Nos. 9,580,848 (Henderson et al.). 9,475,034 (Vincent et al.). 7,491,354 (Anderson), and 6,808,664 (Falk et al.). Fillers (i.e.. insulative inorganic particles and compressible organic particles), by weight, were top or side fed into the chamber or forming box of the air-laid processor. A volumetric feeder coupled with an air-driven horn was used to distribute the fillers into the web uniformly. The sample was then sent through a forced-air convection oven at 143.3°C (290°F) at a speed of 1.1 m/min to activate the binder and bond the web together.

[00162] Densification of prepared webs

[00163] The webs from above were densified to a specified height using a hot press set with a gap set at the specified height.

[00164] For CE 1 and EX 1-10, the samples were placed between two hot plates of the hot press maintained at 300 °F (149 °C) for approximately 10 minutes. A pre-determined amount of pressure was applied for a pre-detennined amount of time to activate the binder. After this step, the densified sample was immediately placed between two plates maintained at room temperature under a pre-determined pressure for a pre-determined time, to lock the web down to the desired thickness. The pressure and time during the heating step were tuned to get to the desired thickness. For example, to obtain an 8-mm final thickness, 1500 Ibf (680 kgf; applied on an area of 250 mm x 100 mm) for 1 min was used.

[00165] For CE 2 and EX 11 to 18, the same procedure as above was used to densify except the samples were pressed at 200°C for 5 min. The thickness was not recorded. [00166] Comparative Example 1 (CE 1) and Examples 1-10 (EX 1-10)

[00167] Articles were prepared following the general method for preparing thermal barriers and densification of the prepared webs using the components as shown in Table 2. The Compression Performance Test 1 was carried out on these samples and the results are shown in Table 2 below.

- 1 - Table 2

* ⁾ a testing gap of 4mm corresponds to a compression of 50% for the sample of 8 mm height testing gap of 2mm corresponds to a compression of 75% for the sample of 8 mm height

[00168] Comparative Example 2 (CE2) and Examples 11-12 (EX 11-12) [00169] Articles were prepared following the general method for preparing thermal barriers and densification of the prepared webs using the weight percent of the components as shown in Table 3. Compression Performance Test Method 2 was performed on the samples and the results are shown in Table 3.

Table 3

[00170] Examples 13-16 (EX 13-16)

[00171] Articles were prepared following the general method for preparing thermal barriers and densification of the prepared webs using the weight percent of components as shown in Table 4. Compression Performance Test Method 2 was performed on the samples and the results are shown in Table 4.

Table 4

[00172] Examples 17 -18 (EX 17-18)

[00173] The general method for preparing thermal barrier above was used in weight amounts are set forth in Table 5. The prepared webs were densified using the method as described above. Note that MB120 is a dispersion of expoandable microspheres, which expanded during processing. Compression Performance Test Method 2 was performed on the samples and the results are shown in Table 5.

Table 5

[00174] Comparative Example 3 (CE 3) and Examples 19-20 (Ex. 19-20) [00175] Articles were prepared following the general method for preparing thermal barriers using the weight percent of components as shown in Table 6. The materials were run targeting a total basis weight of 1050 gsm. Compression Performance Test Method 3 was performed on the samples and the minimum open-gap pressure P(BOL) and maximum pressure at 1.8 mm gap P(EOL) were determined accordingly. The results are shown in Table 6 as the undensified sample. Some samples were densified using a Glenro dual belt compression oven. The webs were densified at 200 °C, 1 m/min, and with 30000 N of force. These densified samples were tested using the Cycle Compression Test 3 and the average results from two samples are reported in Table 6.

Table 6

[00176] This invention may take on various modifications and alterations without departing from its spirit and scope. For example, it is believed that microwave heating can be used to irreversibly or permanently expand the particles made from intumescent materials. It is also believed that using microwave energy, rather than baking in an oven, can result in a more uniform expansion of the intumescent particles within the fiber matrix. Accordingly, this invention is not limited to the above-described but is to be controlled by the limitations set forth in the following embodiments and any equivalents thereof. This invention may be suitably practiced in the absence of any element not specifically disclosed herein. All patents and patent applications cited above, including those in die Background section, are incorporated by reference into this document in total.

Claims

1. A thermal barrier article, comprising: at least one layer of a nonwoven fibrous thermal insulation comprising:

(a) a fiber matrix of inorganic fibers;

(d) a plurality of compressible organic particles dispersed within the fiber matrix;

2. The thermal barrier article according to claim 1, the thermal barrier is compressible.

3. The thermal barrier of claim 2, wherein the thermal barrier exhibits a minimum pressure peak P(min) determined according to the test described in the experimental section of at least 25 kPa, preferably of at least 30 kPa, and more preferably at least 40 kPa, even more preferably at least 50 kPa per Compression Performance Test 2.

4. The thermal barrier of claims 2 or 3. wherein the thermal barrier when tested according to Compression Performance Test Method 3 has a beginning of life of at least 25 kPa and an end of life of at most 2000 kPa.

5. The thermal barrier of any one of claims 2-4, wherein the addition of the compressible organic particles decreases a pressure observed by the thermal barrier article by at least 20% compared to the same thermal barrier article without compressible organic particles.

6. The thennal barrier according to any one of the preceeding claims, wherein the at least one layer of nonwoven fibrous thennal insulation contains an amount of compressible organic particles in the range of from as low as about 0.5% up to as high as about 20% by weight of the at least one layer of nonwoven fibrous thermal insulation.

7. The thermal barrier according to any one of the preceeding claims, wherein the compressible organic particles are expanded microspheres, rubber particles, foam particles, silicone particles, polyurethane particles, or styrenic block copolymer particles, or any combination or mixtures thereof.

8. The thermal barrier according to claim 7, wherein the compressible organic particles are hollow organic microspheres.

9. The thermal barrier according to claim 7. wherein the foam particles are silicone foam particles, polyurethane foam particles, rubber foam particles, polyolefin foam particles, polystyrene foam particles, thermoset foam particles, polyethersulfone foam particles, or other organic foam particles, or mixtures thereof.

10. The thennal barrier according to any one of the preceeding claims, wherein the layer of nonwoven fibrous thennal insulation has an installed thickness in the range of from about 0.5 mm up to less than 20 mm.

11. The thermal barrier according to any one of the preceeding claims, wherein the layer of nonwoven fibrous thennal insulation has a basis weight in the range of from as low as about 100 g/square meter and up to as high as about 5000 g/square meter.

12. The thermal barrier according to any one of the preceeding claims, wherein the thermally insulative inorganic particles comprise particles of one or any combination of the materials selected from the group consisting of inorganic aerogel, xerogel, hollow or porous ceramic microspheres, unexpanded vermiculite, ineversibly or permanently expanded vermiculite, fumed silica, otherwise porous silica, irreversibly or permanently expanded or unexpanded perlite, pumicite, irreversibly or permanently expanded clay, diatomaceous earth, titania and zirconia, or combinations thereof.

13. The thermal barrier according to claim 12. wherein the thermally insulative inorganic particle is fumed silica.

14. The thennal barrier according to claim 12, wherein the thermally insulative inorganic particle is inorganic aerogel.

15. The article of any one of the previous claims, therein the layer of nonwoven fibrous thermal insulation contains an amount of thermally insulative inorganic particle of at least 10 and at most 60 weight % based on the total weight of the nonwoven fibrous thermal insulation.

16. The article of any one of the previous claims, wherein the binder comprises poly ethy lene, polyethylene terephthalate, flame retardant polyethylene terephthalate, epoxy, acrylic polymers, methacrylic polymer, ethylene vinyl acetate, silicone polyurethane, or any combination or mixtures thereof.

17. The article of any one of the previous claims, wherein the binder comprises bicomponent coresheath polymeric fibers.

18. The article of any one of the previous claims, wherein the compressible organic particles are dispersed within an organic resin.

19. The thermal barrier according to any one of the proceeding claims, wherein the thermal barrier further comprises at least one encapsulation layer encapsulating the at least one layer of nonwoven fibrous thermal insulation.

20. The thermal barrier according to claim 19, wherein the at least one encapsulation layer is organic.

21. A battery cell module for an electric vehicle, said battery cell module comprising:

(A) a plurality of battery cells disposed in a housing; and

(B) a plurality of thermal barriers according to any one of the proceeding claims; wherein the battery cells a lined up in a row, with one thermal barrier being disposed between each pair of adjacent battery cells.

22. A method of making the thermal barrier article according to any one of claims 1 to 20, the method comprising: forming a layer of nonwoven fibrous thermal insulation using a wet-laid process or dry -laid process; providing a plurality of thermally insulative inorganic particles; disposing the plurality of thermally insulative inorganic particles so as to be evenly or uniformly distributed throughout or within the layer of nonwoven fibrous thermal insulation; providing a plurality of compressible organic particles; disposing the plurality of compressible organic particles so as to be evenly or uniformly distributed throughout or within the layer of nonwoven fibrous thennal insulation; and providing a binder distributed throughout or within the layer of nonwoven fibrous thermal insulation to provide the thermal barrier article.