Thermal barrier with encapsulated isolation material layer and method

Abstract

A thermal barrier, and associated methods for making the same are disclosed. In one aspect, a thermal barrier includes a porous material. One aspect of a thermal barrier includes an aerogel material. Aspects of thermal barriers are shown that include a conformal coating over an outer porous surface of an isolation material layer, wherein the conformal coating penetrates the outer porous surface of the isolation material layer to a penetration depth.

Description

THERMAL BARRIER WITH ENCAPSULATED ISOLATION MATERIAL LAYER AND METHODCross-Reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Application Serial Number 63 / 530,637, filed August 3, 2023, the content of which is incorporated by reference herein in its entirety.Technical Field

[0002] The present disclosure relates generally to materials and systems and methods for preventing or mitigating thermal events, such as thermal runaway issues, in energy storage systems. In particular, the present disclosure provides thermal barrier materials. The present disclosure further relates to a battery module or pack with one or more battery cells that include(s) the thermal barrier materials, as well as systems including those battery modules or packs. Aspects described generally may include aerogel materials.Background

[0003] Battery packs, such as lithium-ion batteries (LIBs), are widely used in powering portable electronic devices such as cell phones, tablets, laptops, power tools and other high-current devices, such as electric vehicles, because of their high working voltage, low memory effects, and high energy density compared to traditional batteries. However, safety is a concern as LIBs are susceptible to catastrophic failure under ‘'abuse conditions” such as when a rechargeable battery is overcharged (being charged beyond the designed voltage), over-discharged, or operated at or exposed to high temperature or high pressure.

[0004] To prevent cascading thermal runaway events from occurring, there is a need for effective insulation and heat dissipation strategies to address these and other technical challenges of battery packs.Brief Description of the Drawings

[0005] Features of examples of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like referencenumerals correspond to similar, though perhaps not identical, components. For the sake of brevity, reference numerals or features having a previously described function may or may not be described in connection with other drawings in which they appear.

[0006]

[0007] FIG. 1 A is a perspective view of a battery module in accordance with some aspects.

[0008] FIG. IB is a schematic cross-sectional view of another battery module in accordance with some aspects.

[0009] FIG. 2 is a perspective view of a reinforcing network in accordance with some aspects.

[0010] FIG. 3 is a schematic and perspective view of an isolation material layer in accordance with some aspects.

[0011] FIG. 4 is a schematic and perspective view of an example of a thermal barrier, depicting an enlarged view of an area of the isolation material layer shown in FIG. 3 coated with a conformal coating.

[0012] FIG. 5 is a schematic and perspective view of a thermal barrier in accordance with some aspects.

[0013] FIG. 6A is a schematic illustration of an exposed fiber of an uncoated isolation material layer in accordance with some aspects.

[0014] FIG. 6B is a schematic illustration of the exposed fiber FIG. 6A after being coated with a conformal coating in accordance with some aspects.

[0015] FIG. 7A is a schematic and perspective illustration of an uncoated isolation material with isolation material pores in accordance with some aspects.

[0016] FIG. 7B is a schematic and perspective illustration of the isolation material of FIG. 7A after being coated with a conformal coating in accordance with some aspects.

[0017] FIG. 8 is a flow diagram illustrating a method of regulating a battery module in accordance with some aspects.

[0018] FIG. 9 is a schematic illustration of an electronic device in accordance with some aspects.

[0019] FIG. 10 is a schematic illustration of an electric vehicle in accordance with some aspects.

[0020] FTG. 1 1 is a graph depicting the difference between the thermal conductivity (Tc) of a coated isolation material layer and the Tc of the same isolation material layer prior to coating (y-axis. mW / m-K) versus the mean of the thermal conductivity (Tc) of the coated isolation material layer and the Tc of the same isolation material layer prior to coating (x- axis, mW / m-K).

[0021] FIG. 12 is a graph depicting the heat of combustion (HoC) (y-axis, cal / g) for isolation material layers versus the percentage of paralyene coating thereon (x-axis, %).

[0022] FIG. 13 is a graph depicting the heat of combustion (HoC) (y-axis, cal / g) for isolation material layers versus the type of paralyene coating thereon (x-axis).

[0023] FIG. 14 is a graph depicting the mass loss (y-axis, wt%) of uncoated, parylene-C, and parylene-N coated isolation material layers (x-axis) during thermo- gravimetric analysis (TGA) testing.

[0024] FIG. 15 is a graph depicting the heat release (y-axis, J / g) of uncoated, parylene-C, and parylene-N coated isolation material layers (x-axis) during differential scanning calorimetry (DSC) analysis.

[0025] FIG. 16 is a graph depicting the onset temperature (y-axis, °C) of uncoated, parylene-C, and parylene-N coated isolation material layer (x-axis) during DSC analysis.

[0026] Fig. 17 is a graph depicting the peak temperature (y-axis, °C) of uncoated, parylene-C, and parylene-N coated isolation material layer (x-axis) during DSC analysis.

[0027] FIG. 18 is a bar graph illustrating the dimension shrinkage (left y-axes, %) and coating weight (right y-axis, wt%) of non-coated, parylene-C, and parylene-N coated isolation material layers (x-axis) after a hot surface test.

[0028] FIG. 19 is a graph depicting the strain at 1 mPa (y-axis, %) of non-coated, parylene-C, and parylene-N coated isolation material layers versus the coat weight of the coating (x-axis).

[0029] FIG. 20 is a graph illustrating the density increase post coating (y-axis. g / cm3) of the coated isolation material layers according to the increase of the parylene coating amount.

[0030] FIG. 21 is a graph depicting the correlation between the strain at 1 mPa (y- axis, %) and the densities (x-axis, g / cm3) tested at 0.2 PSI pressure of the uncoated, parylene-C and parylene-N coated isolation material layers.

[0031] FIG. 22 is a graph depicting the compression set (y-axis, %) of non-coated, parylene-C, and parylene-N coated isolation material layers (x-axis).

[0032] FIG. 23 is a graph depicting the compression set (y-axis, %) of non-coated, parylene-C, and parylene-N coated isolation material layers (x-axis).

[0033] FIG. 24 is a graph depicting the dust amount (y-axis, mg / m3) of the uncoated, parylene-C and parylene-N coated isolation material layers (x-axis).Detailed Description

[0034] The following description and the drawings sufficiently illustrate specific aspects to enable those skilled in the art to practice them. Other aspects may incorporate structural, logical, electrical, process, and other changes. Portions and features of some aspects may be included in, or substituted for, those of other aspects. Aspects set forth in the claims encompass all available equivalents of those claims.

[0035] The present disclosure is directed to a thermal barrier used between battery’ cells in a battery pack for heat management and mechanical property management. The thermal barrier includes a conformally coated isolation material layer. The isolation material layer includes a porous isolation material deposited in pores of a reinforcing network. Without the conformal coating, the porous isolation material may detach from the pores of the reinforcing network (also referred to as reinforcing network layer) during processing. The conformal coating contours and connects the porous isolation material and the exposed fiber, foam, or other material of the reinforcing network, thereby reducing or eliminating this detachment and prolonging the life of the thermal barrier. Moreover, the conformal coating reduces or eliminates dust and / or debris from the porous isolation material that may otherwise occur during processing. The conformal coating further enhances the mechanical properties and reduces liquid uptake of the isolation material layer. The conformal coating is also referred to as encapsulation. The isolation material layer is also referred to as thermal barrier layer. The conformally coated isolation material layer is also referred to as encapsulated thermal barrier.

[0036] In addition to the isolation material layer, the thermal barrier may further include thermal conductor materials, and / or resilient materials as described in aspects below. The thermal barrier can be used in battery modules to compartmentalize individualcells, or groups of cells in a batery device. Multiple batery cells that are coupled together are referred to in the present disclosure as batery modules. However, devices and methods described can be used in any of several types of multiple cell arrangements, that may be termed baten’ packs, batery systems, etc.Isolation material layers

[0037] The isolation material layer includes a porous isolation material. The porous isolation material as described below can be formulated into a single heat resistant layer, or can be used in combination with other layers that provide additional function to a multilayer configuration, such as mechanical strength, compressibility, heat dissipation / conduction, etc. Isolation material layers described herein are responsible for reliably containing and controlling heat flow from heat-generating parts in small spaces and to provide safety and prevention of heat or fire propagation for such products in the fields of electronic, industrial and automotive technologies.

[0038] In many aspects of the present disclosure, the isolation material layer functions as a heat / flame / fire deflector layer, either by itself or in combination with other materials that enhance the performance of containing and controlling heat flow. In one aspect, the isolation material layer may itself be resistant to heat, flame and / or hot gases, and further include entrained particulate materials that modify or enhance heat containment and control.

[0039] An isolation material layer may include or consist essentially of any kind of isolation material commonly used to separate batery cells or battery modules. Exemplary isolation materials include polymer-based isolation materials (e.g., polypropylene, polyester, polyimide, and aromatic polyamide (aramid)), phase change materials, intumescent materials, aerogel materials, mineral based barrier materials (e.g., mica), inorganic isolation materials (e.g., fiberglass containing barriers), other isolation materials, and combinations thereof.

[0040] One aspect of a highly effective isolation material layer includes an aerogel. Aerogels describe a class of material based upon their structure, namely low density, open cell structures, large surface areas (e.g., 900 m2 / g or higher) and nanometer scale pore sizes. The pores may be filled with gases, such as air. Aerogels can be distinguished from otherporous materials by their physical and structural properties. Although an aerogel material is an exemplary porous isolation material, other porous isolation materials may be used in the thermal barrier.

[0041] Selected aspects of aerogel formation and properties are described. In several aspects, a precursor material is gelled to form a network of pores that are filled with solvent. The solvent is then extracted, leaving behind a porous matrix. In one aspect, the solvent is extracted by supercritical dry ing. During the supercritical drying process, the isolation material (e.g., aerogel) is placed under suitable pressure and temperature to reach the supercritical condition of the solvent. Under supercritical conditions, the solvent can be extracted without damaging the porous matrix due to the reduced surface tension and capillary stress.

[0042] A variety' of different aerogel compositions are known, and they may be inorganic, organic and inorganic / organic hybrid. Inorganic aerogels are generally based upon metal alkoxides and include materials such as silica, zirconia, alumina, and other oxides. Organic aerogels include, for example, urethane aerogels, resorcinol formaldehyde aerogels, and polyimide aerogels, other organic aerogels, and combinations thereof.

[0043] Inorganic aerogels may be formed from metal oxide or metal alkoxide materials. The metal oxide or metal alkoxide materials may be based on oxides or alkoxides of any metal or semi-metal that can form oxides. Such metals or semi-metals include silicon, aluminum, titanium, zirconium, hafnium, yttrium, vanadium, cerium, and the like. Inorganic silica aerogels are made via the hydrolysis and condensation of silica-based alkoxides (such as tetraethoxylsilane), or via gelation of silicic acid or water glass. Other relevant inorganic precursor materials for silica-based aerogel synthesis include, as examples, metal silicates such as sodium silicate or potassium silicate, alkoxysilanes, partially hydrolyzed alkoxysilanes, tetraethoxylsilane (TEOS). partially hydrolyzed TEOS, condensed polymers of TEOS, tetramethoxylsilane (TMOS), partially hydrolyzed TMOS, condensed polymers of TMOS, tetra-n-propoxysilane, partially hydrolyzed and / or condensed polymers of tetra-n-propoxysilane, polyethylsilicates, partially hydrolyzed polyethysilicates, monomeric alkyl al oxy silanes, bis-trialkoxy alkyl or aryl silanes, polyhedral silsesquioxanes. or combinations thereof.

[0044] In certain aspects of the present disclosure, pre-hydrolyzed TEOS, such as SIL-BOND™ H-5 (SBH5, Silco Inc.), which is hydrolyzed with a water / silica ratio of about 1.9-2, may be used as commercially available or may be further hydrolyzed prior to incorporation into the gelling process. Partially hydrolyzed TEOS or TMOS, such as polyethysilicate (SIL-BOND™ 40) or polymethylsilicate may also be used as commercially available or may be further hydrolyzed prior to incorporation into the gelling process.

[0045] Inorganic aerogels can also include gel precursors comprising at least one hydrophobic group, such as alkyl metal alkoxides, cycloalkyl metal alkoxides, and aryl metal alkoxides, which can impart or improve certain properties in the gel, such as stability and hydrophobicity. Inorganic silica aerogels can specifically include hydrophobic precursors such as alkylsilanes or arylsilanes. Hydrophobic gel precursors may be used as primary precursor materials to form the framework of a gel material. However, hydrophobic gel precursors are more commonly used as co-precursors in combination with simple metal alkoxides in the formation of amalgam aerogels. Hydrophobic inorganic precursor materials for silica-based aerogel synthesis include, as examples, trimethyl methoxysilane, dimethyl dimethoxysilane (DMDMS), methyl trimethoxysilane (MTMS), trimethyl ethoxysilane, dimethyl diethoxysilane (DMDS), methyl triethoxysilane (MTES), ethyl triethoxysilane (ETES), diethyl diethoxysilane, dimethyl diethoxysilane (DMDES), ethyl triethoxysilane, propyl trimethoxysilane, propyl triethoxysilane, phenyl trimethoxysilane, phenyl triethoxysilane (PhTES), hexamethyldisilazane and hexaethyldisilazane, and the like. Any derivatives of any of the above precursors may be used. Additionally, certain polymeric or other chemical groups may be added or cross-linked to one or more of the above precursors.

[0046] Organic aerogels are generally formed from carbon-based polymeric precursors. Such polymeric materials include, for example, resorcinol formaldehydes (RF), polyimide, polyacrylate, polymethyl methacrylate, acrylate oligomers, polyoxyalkylene, polyurethane, polyphenol, polybutadiane, trialkoxysilyl-terminated polydimethylsiloxane, polystyrene, polyacrylonitrile, polyfurfural, melamine-formaldehyde, cresol formaldehyde, phenol-furfural, polyether, polyol, polyisocyanate, polyhydroxybenze, polyvinyl alcohol dialdehyde, polycyanurates, polyacrylamides, various epoxies, agar, agarose, chitosan, and combinations thereof. As one aspect, organic RF aerogels are made from the sol-gel polymerization of resorcinol or melamine with formaldehyde under alkaline conditions.

[0047] Organic / inorganic hybrid aerogels are mainly comprised of (organically modified silica (“ormosil”) aerogels. These ormosil materials include organic components that are covalently bonded to a silica network. Ormosils are typically formed through the hydrolysis and condensation of organically modified silanes, R-Si(OX)3, with traditional alkoxide precursors, Y(0X)4. In these formulas, X may represent, for example, CH;,. C2H5, C3H7, C4H9; Y may represent, for example, Si, Ti, Zr, or Al; and R may be any organic fragment such as methyl, ethyl, propyl, buty l, isopropyl, methacrylate, acry late, vinyl, epoxide, and the like. The organic components in ormosil aerogel may also be dispersed throughout or chemically bonded to the silica network.

[0048] Aerogels can be formed from flexible gel precursors. Various flexible layers, including flexible fiber-reinforced aerogels, can be readily combined and shaped to give pre-forms that when mechanically compressed along one or more axes, give compressively strong bodies along any of those axes.

[0049] One method of aerogel formation includes batch casting. Batch casting includes catalyzing one entire volume of sol to induce gelation simultaneously throughout that volume. Gel-forming techniques include adjusting the pH and / or temperature of a dilute metal oxide sol to a point where gelation occurs. Suitable materials for forming inorganic aerogels include oxides of most of the metals or semi-metals that can form oxides, such as silicon, aluminum, titanium, zirconium, hafnium, yttrium, vanadium, and the like. Gels formed primarily from alcohol solutions of hydrolyzed silicate esters may be desirable due to their ready availability and low cost (alcogel). Organic aerogels can also be made from melamine formaldehydes, resorcinol formaldehydes, and the like.

[0050] In one aspect, aerogel materials may be monolithic, or continuous throughout a structure or layer. In other aspects, an aerogel material may include a composite aerogel material with aerogel particles that are mixed with a binder or carrier. Other additives may be included in a composite aerogel material. An example of a suitable additive includes a surfactant that aids in dispersion of aerogel particles within the binder or carrier. A composite aerogel slurry may be applied to a supporting plate such as a mesh, felt, web, etc. and then dried to form the composite aerogel structure.

[0051] As noted above, an aerogel may be organic, inorganic, or a mixture thereof. In some aspects, the aerogel includes a silica-based aerogel. One or more layers in a thermalbarrier may include reinforcement material. The reinforcing material may be any material that provides resilience, conformability, or structural stability to the aerogel material. Aspects of reinforcing materials include, for example, open-cell macroporous framework reinforcement materials, closed-cell macroporous framework reinforcement materials, opencell membranes, honeycomb reinforcement materials, polymeric reinforcement materials, and fiber reinforcement materials such as discrete fibers, woven materials, non-woven materials, needled non-wovens, battings, webs, mats, and felts.

[0052] The reinforcement material can be selected from the group consisting of organic polymer-based fibers, inorganic fibers, carbon-based fibers or a combination thereof. The inorganic fibers are selected from glass fibers, rock fibers, metal fibers, boron fibers, ceramic fibers, basalt fibers, pre-oxidized fibers, pre-oxidized polyacrylonitrile, foam, rubber, resin, polymer, or combination thereof. In some aspects, the fibers are in the form of discrete fibers, woven materials, dry laid non-woven materials, wet laid non-woven materials, air-laid nonwovens, needled nonwovens, battings, webs, mats, felts, and / or combinations thereof. In some aspects, the reinforcement material can include a reinforcement including a plurality of layers of material.Thermal conductive layers

[0053] In addition to the isolation material layer(s), the thermal barrier may further comprise thermal conductor material layers (also referred to as thermal conductive layers, thermally conductive material layers). The thermally conductive material layers in combination with isolation material layers are effective at channeling unwanted heat to a desired external location. Thermal communication between the thermally conductive layer and heat sink elements within the battery system allows the removal of excess heat from the battery cell or cells adjacent to the isolation material layer to the heat sink. The removal of the excess heat reduces the effect, severity, or propagation of a thermal event that may generate excessive heat. In addition to removal of heat, a thermally conductive layer can spread, or dissipate heat from a region of high heat concentration to a larger region of lower heat concentration, thereby reducing the possibility' of local overheat and consequent thermal runaway. In one aspect, a thermally conductive layer or layers help(s) to dissipate heat away from a localized heat load within a battery module or pack.

[0054] High thermal conductivity materials include carbon fiber, graphite, silicon carbide, metals or alloys thereof, such as copper, stainless steel, aluminum, and the like, as well as combinations thereof.

[0055] To further distribute or remove the undesired heat, the thermal conductive layer is coupled to external heat dissipating fins, a heat dissipating housing, or other external structure to dissipate unwanted heat to outside ambient air. In at least one aspect, the thermally conductive layer is coupled to a heat sink. It will be appreciated that there are a variety of heat sink types and configurations, as well as different techniques for coupling the heat sink to the thermally conductive layer, and that the present disclosure is not limited to the use of any one type of heat sink / coupling technique. In one aspect, at least one thermally conductive layer of the multilayer materials disclosed herein can be in thermal communication with an element of a cooling system of a battery module or pack, such as a cooling plate or cooling channel of the cooling system. In another aspect, at least one thermally conductive layer can be in thermal communication with other elements of the battery pack, battery module, or batten system that can function as a heat sink, such as the walls of the pack, module or system, or with other multilayer materials disposed between battery’ cells.Resilient material layers

[0056] In addition to the isolation material layers and thermal conductive layers, the thermal barrier may further comprise one or more resilient material layers. In one aspect, a resilient layer absorbs any volume expansion during the regular operation of one or more battery cells. For example, during a charge, the cells may expand, and during a discharge, the cells may shrink. In one aspect, the resilient material layer may also absorb permanent volume expansion caused by any battery cell aging, degradation, and / or thermal runaway. Resilient material layers may include, for example, foam, fiber, fabric, sponge, spring structures, rubber, polymer, resin, etc.Characterization of the thermal barriers / heat isolation material layers

[0057] Within the context of the present disclosure, the terms "‘thermal conductivity ” and “TC” refer to a measurement of the ability of a material or composition totransfer heat between two surfaces on either side of the material or composition, with a temperature difference between the two surfaces. Thermal conductivity is specifically measured as the heat energy transferred per unit time and per unit surface area, divided by the temperature difference. It is typically recorded in SI units as mW / m*K (milliwatts per meter * Kelvin). The thermal conductivity of a material may be determined by methods known in the art, including: Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus (ASTM C518, ASTM International, West Conshohocken, PA); a Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus (ASTM Cl 77, ASTM International, West Conshohocken, PA); a Test Method for Steady-State Heat Transfer Properties of Pipe Insulation (ASTM C335, ASTM International, West Conshohocken, PA); a Thin Heater Thermal Conductivity Test (ASTM Cl 114, ASTM International, West Conshohocken. PA); Determination of thermal resistance by means of guarded hot plate and heat flow meter methods (EN 12667, British Standards Institution, United Kingdom); or Determination of steady-state thermal resistance and related properties - Guarded hot plate apparatus (ISO 8203. International Organization for Standardization, Switzerland). Within the context of the present disclosure, thermal conductivity measurements are acquired according to ASTM Cl 77 standards, at a temperature of about 37.5°C, at atmospheric pressure, and at a compression of about 2 psi, unless otherw ise stated. Preferably, aerogel materials or compositions, or thermal barriers of the present disclosure have a thermal conductivity of about 50 mW / mK or less, about 40 mW / mK or less, about 30 mW / mK or less, about 25 mW / mK or less, about 20 mW / mK or less, about 18 mW / mK or less, about 16 mW / mK or less, about 14 mW / mK or less, about 12 mW / mK or less, about 10 mW / mK or less, about 5 mW / mK or less, or in a range between any two of these values.

[0058] Within the context of the present disclosure, the term “density” refers to a measurement of the mass per unit volume of an aerogel material or composition, or a thermal barrier. In an example, the term “density” refers to the true density of an aerogel material, as well as the bulk density' of an aerogel composition. Density is typically recorded as kg / m3, g / cm3or g / cc. The density of an aerogel material or composition, or of a thermal barrier may be determined by methods known in the art. including: Standard Test Methodfor Dimensions and Density of Preformed Block and Board-Type Thermal Insulation (ASTM C303, ASTM International, West Conshohocken, PA); Standard Test Methods for Thickness and Density of Blanket or Batt Thermal Insulations (ASTM Cl 67, ASTM International, West Conshohocken. PA); or Determination of the apparent density of preformed pipe insulation (ISO 18098, International Organization for Standardization, Switzerland). Within the context of the present disclosure, density measurements are acquired according to ASTM Cl 67 standards, unless otherwise stated. Preferably, aerogel materials or compositions, or thermal barriers of the present disclosure have a density of about 0.60 g / cc or less, about 0.50 g / cc or less, about 0.40 g / cc or less, about 0.30 g / cc or less, about 0.25 g / cc or less, about 0.20 g / cc or less, about 0. 18 g / cc or less, about 0.16 g / cc or less, about 0.14 g / cc or less, about 0.12 g / cc or less, about 0.10 g / cc or less, about 0.05 g / cc or less, about 0.01 g / cc or less, or in a range between any two of these values.

[0059] Within the context of the present disclosure, the densities of the non-coated isolation material layer and the conformally coated isolation material layer (i.e., thermal barriers) are calculated by dividing the mass of the non-coated or conformally coated isolation material layer by a nominal volume. The nominal volume is calculated by a standard surface area multiplied by each individual thickness value of the non-coated or conformally coated isolation material layer. The individual thickness values of the isolation material layer are measured using a handheld snap gauge. The standard surface area is used to cut the non-coated isolation material layers for the conformal coating experiment. The standard surface area is used instead of individual surface area because the individual surface area has very small and negligible variations from the standard surface area.

[0060] Within the context of the present disclosure, the terms ‘'heat of combustion” and “HoC” refer to a measurement of the amount of heat energy released in the combustion of an aerogel material or composition, or a thermal barrier. Heat of combustion is typically recorded in calories of heat energy released per gram of aerogel material or composition, or thermal barrier (cal / g), or as megajoules of heat energy released per kilogram of aerogel material or composition, or thermal barrier (MJ / kg). The heat of combustion of a material or composition may be determined by methods known in the art, including: Reaction to fire tests for products - Determination of the gross heat of combustion (calorific value) (ISO 1716, International Organization for Standardization, Switzerland). Within the context ofthe present disclosure, heat of combustion measurements are acquired according to conditions comparable to ISO 1716 standards, unless otherwise stated. In one aspect, the HoC is tested using an oxygen bomb calorimeter. The heat of combustion as measured in a bomb calorimeter denotes the heat liberated by the combustion of all carbon and hydrogen with oxygen to form carbon dioxide and water, including the heat liberated by the oxidation of other elements such as sulfur. The samples (e.g., aerogel compositions) are pulverized using a rotary' “swing mill” grinder, until the grinded samples are less than 60 mesh or smaller. The grinded samples are compressed into a pellet thereafter for HoC tests.

[0061] Preferably, aerogel materials or compositions or thermal barriers of the present disclosure can have a heat of combustion of about 750 cal / g or less, about 717 cal / g or less, about 700 cal / g or less, about 650 cal / g or less, about 600 cal / g or less, about 575 cal / g or less, about 550 cal / g or less, about 500 cal / g or less, about 450 cal / g or less, about 400 cal / g or less, about 350 cal / g or less, about 300 cal / g or less, about 250 cal / g or less, about 200 cal / g or less, about 150 cal / g or less, about 100 cal / g or less, about 50 cal / g or less, about 25 cal / g or less, about 10 cal / g or less, or in a range between any two of these values. An aerogel material or composition, or thermal barrier which has an improved heat of combustion relative to another aerogel material or composition, or thermal barrier will have a lower heat of combustion value, relative to the reference aerogel material or composition, or thermal barrier.

[0062] Within the context of the present disclosure, the terms “onset of thermal decomposition of hydrophobic organic material,” “onset of thermal decomposition,” “onset temperature,” and “Ta” refer to a measurement of the lowest temperature of environmental heat at which rapid exothermic reactions from the decomposition of hydrophobic organic material appear within a material or composition. The onset of thermal decomposition of a material or composition may be measured using thermo-gravimetric analysis (TGA). The TGA curve of a material depicts the weight loss (%mass) of a material as it is exposed to an increase in surrounding temperature. The onset of thermal decomposition of a material can be correlated with the intersection point of the following tangent lines of the TGA curve: a line tangent to the base line of the TGA curve, and a line tangent to the TGA curve at the point of maximum slope during the rapid decomposition event related to the decomposition of hydrophobic organic material. Within the context of the present disclosure.measurements of the onset of thermal decomposition of hydrophobic organic material are acquired using TGA analysis as provided in this paragraph, unless otherwise stated.

[0063] The onset of thermal decomposition of a material may also be measured using differential scanning calorimetry (DSC) analysis. The DSC curve of a material depicts the heat energy (mW / mg) released by a material as it is exposed to a gradual increase in surrounding temperature. The onset of thermal decomposition temperature of a material can be correlated with the point in the DSC curve where the A mW / mg (change in the heat energy output) maximally increases, thus indicating exothermic heat production from the aerogel material. Within the context of the present disclosure, measurements of onset of thermal decomposition using DSC are acquired using a temperature ramp rate of 20°C / min or less and a temperature sweep range of ambient to 1000°C, unless otherwise stated.

[0064] Preferably, aerogel materials or compositions of the present disclosure have an onset of thermal decomposition of about 100°C or more, about 150°C or more, about 200°C or more, about 250°C or more, about 300°C or more, about 350°C or more, about400°C or more, about 450°C or more, about 500°C or more, about 550°C or more, about600°C or more, about 650°C or more, about 700°C or more, about 750°C or more, about800°C or more, or in a range between any two of these values. An aerogel material or composition which has an improved onset of thermal decomposition relative to another aerogel material or composition will have a higher onset of thermal decomposition temperature relative to the reference aerogel material or composition.

[0065] Within the context of the present disclosure, the term “compression set” is a measurement of the permanent deformation of a material remaining after removal of a force that was applied to the material. In the present disclosure, compression set is determined using ASTM D3574 - Test D. The compression set is determined as a percentage of change in the thickness (tks) of a material before and after the application of a predetermined force. In one example of ASTM D3574 - Test D. compression set can be determined from the following formula:Ct = [(To - Tf) / (To-Ts] X 100

[0066] where Ct is the compression set; Tois the original thickness of the material; Ts is the thickness of the shim or spacer bar that is used during the compressive test to set the stop point of the compression, and Tr is the final thickness of the material after removalan applied force. For example, the Tsis 1mm if a 2mm sample is compressed to 50% strain. Within the context of the present disclosure, the term “shrinkage” is a measurement of the permanent deformation of a material that remains following a hot surface test. The shrinkage in length, width, and thickness are the differences in the length values, width values, and thickness values, respectively, before and after the exposure to a hot surface test. The hot surface test is a simulation of a thermal runaway test of a battery pack. In a thermal runaway test, one battery' cell in the pack is triggered to be overheated to examine its impact on adjacent battery cells. The thermal barrier is placed between the triggered battery cell and the adjacent battery cell to mitigate heat propagation therebetween. In a hot surface test, a thermal barrier is placed on a hot surface mimicking the thermal runaway cell in the thermal runaway test. The length, width, and thickness of the thermal barrier are measured before and after exposure to the hot surface to measure the respective shrinkage in length, width, and thickness. The hot surface may be a hot wall of an oven. The hot surface temperature ramps to about 950°C or more with a ramp rate of about 35°C / min or more during a hot surface test. In aty pical hot surface test, the isolation material layer has a temperature of about 930°C + 10°C on the opposite side of the hot surface.

[0067] Preferably, aerogel materials or compositions, or thermal barriers of the present disclosure have a length shrinkage of about 1% to about 7%, 2% to about 6%, 2% to about 5%, or in a range between any two of these values. The aerogel materials or compositions, or thermal barriers of the present disclosure have a width shrinkage of about 1% to about 5%, 2% to about 5%, 2% to about 4%, or in a range between any two of these values. The aerogel materials or compositions, or thermal barriers of the present disclosure have a width shrinkage of about 0.1 % to about 15%, 4% to about 12%, 4% to about 10%, or in a range between any two of these values. As is illustrated in at least some of the Examples set forth herein, the isolation material layer with the conformal coating has less thickness reduction compared to the non-coated isolation material layer.

[0068] Within the context of the present disclosure, the term “strain” refers to a deformation from compression of the aerogel material or composition, or of the thermal barrier. An aerogel material or composition, or thermal barrier is compressed at a constant rate (cross head speed of 0.5mm / min) until a stress of 1 MPa is reached. The aerogel material or composition, or thermal barrier is then relaxed at the same cross-head speedwithout holding it at high pressure. Strain is measured in % while stress is measured in units of pressure (e.g., psi or MPa). For example, the strain rate achieved is 50% when a 2 millimeter (mm) thick sample is compressed down to 1 mm under a force of 1 MPa. A very flexible aerogel material or composite, or thermal barrier has a higher strain rate at the same stress level (i.e., samples that are extremely rigid are better able to resist the applied stress with less deformation / deflection). Adding parylene serves to reduce the strain of the aerogel material or composite. In other words, the conformally coated aerogel material or composite is stiffer than its non-coated counterpart.

[0069] Within the context of the present disclosure, the terms “dust’ ’ and “debris” refer to the loose isolation material that falls off the reinforcing network. The porous isolation material may be aerogel powder, such as a silica aerogel powder, organic aerogel powder, other aerogel powders, or combinations thereof. The reinforcing network (also referred to as the reinforcing network layer) may be a fiber network, such as glass fiber, PET fiber, PE fiber, other suitable fibers, or combinations thereof, or a foam.

[0070] The dust amount of a material or composition, or a thermal barrier may be determined by methods and devices known in the art, including, for example, a DustTrak™ from TSI. The aerosol monitor generates dust values by light scattering optics coupled with a photodetector which is used to determine mass concentration of particulate dust in real time. A small hose in the dust tracking device is placed over an inlet port of the pump of the dust tracking device. The pump creates a slight vacuum during operation, which sucks in any dust from the sample surface for dust amount analysis.

[0071] The dust value of the non-coated aerogel material or composition ranges from about 0. 1 mg / m3to about 25 mg / m3, about 2 mg / m3to about 25 mg / m3, about 5 mg / m3to about 15 mg / m3, about 7.5 mg / m3to about 12.5 mg / m3, or in a range between any two of these values. The conformal coating disclosed herein significantly reduces the dust values. As examples, the dust value of the coated aerogel material or composition (i.e., one example of the thermal barrier) is less than about 5 mg / m3, less than about 2.5 mg / m3, less than about 1 mg / m3, or less than about 0.5 mg / m3.Encapsulated isolation material layer

[0072] Figure 1A shows one aspect of a batten- module 100. In one aspect, the battery- module 100 includes a number of cells 102 electrically coupled together; an isolation material layer 110 between at least two cells 102A. 102B in the number of cells 102, the isolation material layer 1 10 including an outer porous surface; and a conformal coating 420 over the outer porous surface of the isolation material layer 110, wherein the conformal coating 420 penetrates the outer porous surface of the isolation material layer 110 to a penetration depth in a range of about 2 nanometers to about 800 microns, about 2 nanometers to about 500 microns, about 500 nanometers to about 250 microns, about 2 microns to about 500 microns, about 50 microns to about 300 microns, about 150 microns to about 250 microns, or any ranges therebetween.

[0073] The module 100 includes a stack number of battery cells 102, which may be referred to as a stack of cells 102. In one aspect, the stack of cells 102 includes lithium-ion cells 102, although other cell types are within the scope of the present disclosure. Several configurations of lithium-ion cells 102 are possible. In one aspect, the stack of lithium-ion cells 102 includes lithium-ion prismatic cells or lithium-ion pouch cells, although other cells are contemplated as being within the purview of this disclosure. The cells 102 in Figure 1A each include electrical terminals 104.

[0074] The battery module 100 further includes a thermal barrier 400, which includes the isolation material layer 110 and the conformal coating(s) 420 over the outer porous surface(s) of the isolation material layer 110. As noted above, it is desirable for the isolation material layer 110 to stop or mitigate thermal runaway conditions that can occur in cells 102, such as lithium-ion cells 102. The isolation material layer 1 10 is also referred to as a thermal barrier layer 110. Thinner isolation material layers 110 provide more space in a battery- module 100 for the batteries and reduce the overall size of the battery- module 100, while still providing thermal insulation.

[0075] Figure IB shows another configuration of a battery module 100’ that includes a heat sink 154 located on a side of the module 100’, and in thermal communication with the battery- cells 102. Figure IB shows a cross section of the batterymodule 100’. One or more of the cells 102 are shown separated by one or more thermal barriers 400. In Figure IB. select groups 112, 114. 116 of cells 102 are separated byrespective thermal barriers 400. In other aspects, every cell 102 is separated from each adjacent cell 102 by a thermal barrier 400, and thus is bounded by respective thermal barriers 400. It is to be understood that side, bottom, or top surfaces of the battery module 100’ may also include thermal barriers 400. Aspects of the thermal barrier 400. including the isolation material layer(s) 1 10 and the conformal coating(s) 420, are shown in more detail in the discussion of Figures below.

[0076] Figure 2 shows a reinforcing network 200 (also referred to as the reinforcing network layer 200) that is included in selected aspects of the thermal barrier 400. The reinforcing network 200 includes a number of reinforcing network pores 202 defined by interconnected reinforcing structure 204. The reinforcing network pores 202 are also referred to herein as reinforcing structure pores 202. In one aspect, the reinforcing network pores 202 each have a diameter (or largest diameter if non-spherical) ranging from about 1 nanometer (nm) to about 5 microns (pm), from about 2 nm to about 3 pm, from about 5 nm to about 1 pm, from about 10 nm to about 0.5 pm, or any ranges between about 1 nm and about 5 pm. The reinforcing network 200 may comprise any of the reinforcing materials described above. In some aspects, the reinforcing network materials may include polymers (such a polyurethane foam), metal foams, etc. In one aspect, the reinforcing network 200 includes a fiber network, where the reinforcing structure 204 includes separate fibers that may be laid against one another, and / or may be entangled to form the reinforcing network 200. Aspects of fibers include polymer fibers, polyacrylonitrile (PAN) fibers, pre-oxidized PAN fibers, inorganic fibers, carbon-based fibers or a combination thereof. In one aspect, the inorganic fibers include glass fibers, rock fibers, metal fibers, boron fibers, ceramic fibers, basalt fibers, or combination thereof.

[0077] Figure 3 shows an isolation material layer 110 without a coating. In this example, the isolation material layer 110 includes the reinforcing network 200 of Figure 2 and a porous isolation material 302. As such, in one aspect, the reinforcing network 200 and porous isolation material 302 are included in an isolation material layer 110. The isolation material layer 110 may be included in a battery module 100, 100’ similar to the isolation material layer 110 in Figures 1 A and IB. In one aspect, the porous isolation material 302 includes an aerogel material. The isolation material 302 of Figure 3 illustrates an aerogel material, having a number of aerogel pores 304 (also referred to herein as isolation materialpores 304). The isolation material 302 and the reinforcing network 200 are collectively referred to as a fiber-reinforced aerogel. In one aspect, aerogel pores 304 each have a diameter (or largest diameter if non-spherical) ranging from about 1 nm to about 1000 nm, from about 2 nm to about 800 nm, from about 5 nm to about 500 nm, from about 10 nm to about 100 nm, or any ranges between about 1 nm and about 1000 nm. In one aspect, the porous structure of the isolation material layer 110 includes both the aerogel pores 304 and the reinforcing network pores 202 of Figure 2.

[0078] The isolation material layer 110 may be used as the isolation material layer 110 in the examples shown in Figures 1 A and IB. Although the reinforcing network 200 is included in the aspects of Figures 2 and 3, it is to be understood that in other aspect, the isolation material layer includes the aerogel material without the reinforcing network 200. As such, other isolation material layers 110 that may be included in the batten' modules 100. 100’ shown in Figures 1A and IB may include the aerogel material without the reinforcing network 200.

[0079] In one aspect, the porous isolation material 302 includes aerogel particles that are mixed with a binder or carrier material, such as a polymer adhesive. In one aspect, the porous isolation material 302 includes aerogel particles only, without any binder or carrier material. In one aspect, the porous isolation material 302 includes a substantially monolithic aerogel material. In one aspect, an aerogel includes a silica-based aerogel. In one aspect, the porous isolation material 302 is cast around, and at least partially covers the reinforcing network 200. In one aspect, the porous isolation material 302 is layered with the reinforcing network 200.

[0080] In one aspect, the isolation material layer 1 10 includes additional components, such as particle additives and / or additional layers, etc. In one aspect, the particle additives may include heat absorbents, phase change materials, heat reflective materials, heat conductive materials, flame retardants, intumescent materials, or combinations thereof. In one aspect, the additional layers include resilient material layers to absorb expansion and contraction of battery cells 102 in a battery module 100, 100’. In one aspect, the additional layers include thermal conductive layers that may couple to the heat sink 154. In still another aspect, the additional layers may include both resilient material lavers and thermal conductive layers.

[0081] One or more components of the isolation material layer 110 may be mechanically fragile, or less resilient than other isolation material layer 110 components. A more fragile component may be prone to breaking off of an exposed surface of the isolation material layer 110, causing unwanted dust or debris. For example, the porous isolation materials 302 may become loose and detach from the isolation material layer 110, which causes dust and debris. The porous isolation materials 302 often include very fine detailed surface structure such as pores 304 or portions of pores 304. It is desirable to strengthen the attachment of these fine detailed surface structure features within the isolation material layer 110. Strengthening the attachment of the fine detailed surface structure features (e.g., of the porous isolation materials 302) reduces dust by reducing breakage of such fine detailed surface structure features.

[0082] Figure 4 shows an enlarged view of a portion of a thermal barrier 400. The thermal barrier 400 depicted in Figure 4 includes the outermost portion 306 of the isolation material layer 110 that is identified in Figure 3, and also includes the conformal coating 420 formed at least on the exterior surface of the portion 306 of the isolation material layer 110.

[0083] In Figure 4, the thermal barrier 400 includes a reinforcing network including a reinforcing structure 204 that defines a number of reinforcing structure pores 202. The thermal barrier 400 further includes a porous isolation material 302 with a number of isolation material pores 304. Similar to the aspect shown in Figures 2 and 3, in one aspect, the porous isolation material 302 is located at least partially within the reinforcing structure pores 202 of the reinforcing network 200.

[0084] In Figure 4, the conformal coating (encapsulation) 420 is included over an outer (exterior) surface of the isolation material layer 300. The conformal coating 420 contours the reinforcing structure 204. The conformal coating 420 follows the surface profile of the reinforcing structure 204. The reinforcing structure 204 maintains its surface profile (e.g., curves, pores, extrusions, dents, caves, fibers) after the conformal coating 420 is formed thereon. In one aspect, an exposed fiber 406 in the reinforcing structure 204 has an initial shape, and maintains this shape after the conformal coating 420 is formed thereon. One or more exposed fibers 406 may form reinforcing structure pores 202 within the reinforcing structure 204, where the conformal coating 420 contours the reinforcing structure pores 202. The conformally coated reinforcing structure pore 202 maintains theshape of the reinforcing structure pore 202 before the conformal coating 420 has been formed thereon.

[0085] A first advantage of the conformal coating 420 is to strengthen the attachment of the porous isolation material 302 to within the thermal barrier 400. When the reinforcing network 200 is not present, the conformal coating 402 helps to attach the fine detailed surface structure features of the porous isolation material 302 to each other. When the reinforcing network 200 is included, the conformal coating 402 helps to attach the fine detailed surface structure features of the porous isolation material 302 to each other and helps to attach the porous isolation material 302 to the reinforcing network 200. Both aspects are advantageous over the non-coated isolation material layers or the non- conformally coated isolation material layers. The enhanced attachment reduces or prevents the formation of dust and / or debris from the isolation material 410 during processing.

[0086] In an example, the conformal coating 420 disclosed herein is parylene. Parylene can be conformally coated with a relatively low thickness to improve the attachment of the porous isolation material 302 to itself (i.e., it does not break off) and to the reinforcing network 200 (if used).

[0087] Conformal coating has not been reported to be used on dusty surfaces, such as the isolation material layer 300. Conformal coating on dusty surfaces is easily detachable from the surface together with the dust when the conformal coating is thin. It requires a high coating thickness to keep the coating on a dusty surface. However, thick coatings are not conformal and often cause other undesired physical, thermal, mechanical, and chemical properties.

[0088] The unique properties of the isolation material layer disclosed herein and the unique interaction between the isolation material layer 110 and the conformal coating 420disclosed herein enable a durable and strong conformal coating 420 to be formed over at least a portion of the isolation material layer 110.

[0089] A second advantage of the conformal coating 420 includes limited or no change to thermal properties of the isolation material layer 110. Because structures, such as reinforcing structure pores 202, isolation material pores 304, and exposed fibers 406, are conformally coated (e.g., contoured, encapsulated), but not filled, air spaces remain substantially intact at the exterior surface of the isolation material layer 110. and thus at theexterior surface of the thermal barrier 400. This preserves the ability of air spaces to provide thermal isolation. In other words, because the conformal coating 420 is over an outer surface of the isolation material layer 110 and coats the structures a predetermined depth into the isolation material layer 110, air spaces within an interior of the isolation material layer 110 are undisturbed, and provide a high level of thermal insulation.

[0090] A third advantage of the conformal coating 420 is to improve or maintain the mechanical properties of the isolation material layer 110 and its fine detailed surface structure features, such as reinforcing structure pores 202, isolation material pores 304, and exposed fibers 406. Mechanical properties of the conformal coating 420 material are chosen to be more mechanically robust than the structures, such as reinforcing structure pores 202, isolation material pores 304, and exposed fibers 406 of the reinforcing network 200. Inclusion of the specific conformal coating 420 with improved mechanical properties relative to the structures (e.g., reinforcing structure pores 202, isolation material pores 304, and exposed fibers 406) reduces breakage of such structures, and, in turn, reduces unwanted dust and debris. The use of parylene as the conformal coating 420 unexpectedly led to improvements in the mechanical properties and the reduction of dust and debris. Usually coating (e g., non-conformal coating) would lead to degraded mechanical properties due to the thickness of the coating and / or the interaction between the coating and the isolation material layer 110.

[0091] The improved or maintained mechanical property' or properties of the isolation material layers 110 (and thus the thermal barrier 400) comprise one or more of: tensile strength, hardness, toughness, surface roughness, and stiffness. In one aspect, a tensile strength of the conformal coating 420 is higher than the reinforcing network 200 and than one or more components of structures, such as reinforcing structure pores 202, isolation material pores 304, and exposed fibers 406. In one aspect, a hardness of the conformal coating 420 is higher than the reinforcing network 200 and than one or more components of structures, such as reinforcing structure pores 202, isolation material pores 304, and exposed fibers 406. In one aspect, a toughness of the conformal coating 420 is higher than the reinforcing network 200 and than one or more components of structures, such as reinforcing structure pores 202, isolation material pores 304, and exposed fibers 406. In one aspect, a surface roughness of the isolation material layer 110 with theconformal coating 420 thereon (i.e., of the thermal barrier 400) is less than a surface roughness of the isolation material layer 110 without conformal coating 420 thereon. In one aspect, a stiffness of the isolation material layer 110 with the conformal coating 420 thereon (i.e.. of the thermal barrier 400) is greater than a stiffness of the isolation material layer 110 without conformal coating 420 thereon (e.g., lower strain rates are required after coating to hit same nominal stress target).

[0092] A fourth advantage of the conformal coating 420 is to decrease the liquid / moisture uptake of the isolation material layer 110, and thus the thermal barrier 400. By decreasing the liquid / moisture uptake, the thermal barrier 400 repels moisture and / or possible organic vapor or liquid leaked from the adjacent battery cells 102. In addition, the decrease in liquid / moisture uptake provided by the conformal coating 420 enables a simplified manufacturing process and a subsequent cost reduction. For example, steps (e.g.. surface modification steps) to reduce the liquid / moisture uptake can be removed from the manufacturing process of the isolation material layer 1 10 as a result of the reduced liquid / gas uptake introduced by the conformal coating 420. A percentage of liquid uptake of the isolation material layer 110 with the conformal coating 420 (i.e., of the thermal barrier 400) is less than about 10%, less than about 5%, less than 3%, or less than 1%.

[0093] Within the context of the present disclosure, the term “liquid / moisture uptake” refers to a measurement of the potential of an isolation material layer or a thermal barrier formed therewith to absorb or otherwise retain liquid or gas. Liquid / gas uptake can be expressed as a percent (by weight or by volume) of liquid which is absorbed or otherwise retained by the isolation material layer or thermal barrier when exposed to liquid or gas under certain measurement conditions.

[0094] The physical, thermal, and mechanical properties of the isolation material layer 110 derives from the uniqueness of the combination of the isolation material pores 304. the reinforcing structure pores 202, and the conformal coating 420. The relevant properties for the isolation material pores 304 and the reinforcing structure pores 202 include pore size, pore size distribution, pore structure, etc. The relevant conformal coating 420 properties include conformality, coating weight, coating thickness, coating penetration thickness, etc. In one aspect, the conformal coating 420 penetrates into the isolation material pores 304 conformally to glue or bind the particles of the isolation material 302 frombreaking off from the isolation material layer 1 10. In another aspect, the conformal coating 420 penetrates into the reinforcing structure pores 202 conformally to glue or bind the isolation material 302 to the exposed fiber 406 of the reinforcing structure 204.

[0095] The impact of the conformal coating 420 on the isolation material layer 110 are discussed separately below. Examples 1 to 7 include further details regarding the impact of the conformal coating 420 on the properties of the isolation material layers 110.Coating / encapsulation impact on physical properties of the isolation material layer

[0096] In one aspect, the BET surface aera of the conformally coated isolation material layer (i.e., the thermal barrier 400) is lower than the non-coated isolation material layer 110. In one aspect, the non-coated isolation material layers 110 have BET surface area ranges from about 200 m2 / g to about 500 m2 / g. 250 m2 / g to about 350 m2 / g, or about 250 m2 / g to about 300 m2 / g. The surface areas of the coated isolation material layers (i.e., thermal barriers 400) are directly related to the coating weight. The types of coating (e g., parylene-C or parylene-N coating) show less impact on the BET surface area compared to the coating weights. In one aspect, the BET surface areas of the coated isolation material layers 400 range from about 200 m2 / g to about 220 m2 / g when the coating weights ranges from about 10 wt% to about 15 wt%. In one aspect, the BET surface areas of the coated isolation material layers 400 range from about 100 m2 / g to about 200 m2 / g when the coating weights ranges from about 15 wt% to about 35 wt%. The coating weight is the weight of coating that is applied divided by the weight of the non-coated isolation material layer. For example, the coating weight is 10% if an isolation material layer of 500g is coated with 50g of conformal coating. In one aspect, the BET surface areas of the parylene coated isolation material layers (thermal barriers) range from about 95 m2 / g to about 170 m2 / g when the coating weights are about 40 m2 / g. Example 1 below further demonstrates the effect of the conformal coating 420 on the BET surface aera and the normalized BET aera of the isolation material layer 110. The normalized BET surface area is calculated based on the weight of the isolation material layer 110 without considering the weight of the conformal coatings. The normalized BET surface areas of the isolation material layers range from 130 m2 / g to 400 m2 / g.Coating / encapsulation impact on thermal properties of the isolation material layer

[0097] In one aspect, the heat of combustion (HoC) of the isolation material layer 110 correlates with the conformal coating 420. In one aspect, the HoC of the isolation material layer 110 with conformal coating 420 is proportional to the coating weight. In other words, the HoC of the conformally coated isolation material layer 110 increases proportionally with the increasing coating weights. In one example, the non-coated isolation material layer 110 has a HoC between about 500 cal / g to about 2000 cal / g, about 800 cal / g to about 1500 cal / g. or about 900 cal / g to about 1100 cal / g, while the HoC of the coated isolation material layer 400 ranges from about 800 cal / g to about 3500 cal / g, about 800 cal / g to about 2000 cal / g, or about 1000 cal / g to about 2000 cal / g. Example 3 below further demonstrates the effect of the conformal coating 420 on the HoC of the isolation material layer 110.

[0098] In one aspect, the thermal conductivity (Tc) of the isolation material layer 110 increases with the coating weights of the conformal coating 420. In one coating example, the Tc increases about 1.5 mW / m-K to about 2.5 mW / m-K with a light coating weight of about 10 wt% to about 20 wt% of the isolation material layer 400. The Tc increases about 2.0 mW / m-K. to about 2.75 mW / m-K with a heavy coating weight of about 20 wt% to about 40% wt% of the isolation material layer 400. In a different coating example, the Tc increases about 2.5 mW / m-K to about 5 mW / m-K with a light coating w eight of about 10 wt% to about 20 wt% of the isolation material layer 400. The Tc increases about 2.75 mW / m K to about 9 mW / m- K with a heavy coating weight of about 20 wt% to about 40% wt% of the isolation material layer 400. Example 2 below further demonstrates the effect of the conformal coating on the thermal conductivity of the isolation material layer 400.

[0099] The weight loss of the conformally coated isolation material layer (i.e., thermal barrier 400) in a TGA test generally corresponds to the weight of the conformal coating 420, which is an indication that the conformal coating is burned off during the TGA test. In one example, the weight loss of the conformally coated isolation material layer ranging from about 10% to about 30% corresponds to the conformal coating w eight ranging from about 10% to about 30%. In one example, the weight loss of the conformally coated isolation material layer ranging from about 25% to about 40% corresponds to the conformalcoating weight ranging from about 25% to about 40%. Example 4 below further demonstrates the effect of the conformal coating 420 on the weight loss of the isolation material layer 110 in TGA test.

[0100] The heat release of the conformally coated isolation material layer (i.e., thermal barrier 400) during a TGA test corresponds to the weight of the conformal coating 420. The heat release ranges from 1000-3000 J / g, 1500-2000 J / g, or 1800-2200 J / g for coating weights of 25 wt% - 40 wt% of the isolation material layer 400. Example 4 below further demonstrates the effect of the conformal coating 420 on the heat release of the isolation material layer 110.

[0101] The onset temperature of the isolation material layer 110 in a DSC test decreases with the conformal coating 420. The non-coated isolation material layer 110 has an onset temperature of 400°C to about 700°C, about 400°C to about 700°C, or about 400°C to about 700°C. The onset temperature of the isolation material layer 110 with conformal coating 420 thereon (i.e., the thermal barrier 400) reduces the onset temperature to about 150°C to about 350°C, about 200°C to about 300°C, or about 250°C. Without wishing to be bound by theory', the decrease in onset temperature is triggered by the coating material, which has a lower onset temperature compared to the non-coated isolation material layer 110. Example 4 below further demonstrates the effect of the conformal coating 420 on the onset temperature of the isolation material layer 110.Coating impact on mechanical properties of the isolation material layer

[0102] In one aspect, the conformal coating 420 reduces the shrinkage of the isolation material layer 1 10 in length, width, and / or thickness direction. The reduction in thickness shrinkage is greater than the reduction in length shrinkage or width shrinkage with the conformal coating 420. In other words, the conformal coating 420 is more effective in reducing thickness shrinkage than reducing shrinkage in length or width. The thickness shrinkage of the non-coated isolation material layer 110 is about 5% to about 15%, about 7% to about 12%, or about 9% to about 10%. The thickness shrinkage of the conformally coated isolation material layer (i.e., thermal barrier 400) ranges from about 0. 1% to about 12%, about 0.5% to about 10%, about 2% to about 8%, or about 4% to about 6%. The length shrinkage of the non-coated isolation material layer 110 is about 1% to about 8%,about 2% to about 6%, or about 3% to about 5%. The length shrinkage of the conformally coated isolation material layer (i.e., thermal barrier 400) ranges from about 0.5% to about 5%, about 1% to about 4%, or about 2% to about 4%. The width shrinkage of the noncoated isolation material layer (i.e.. thermal barrier 400) is about 1% to about 5%. about 2% to about 4%, or about 2.5% to about 4%. The width shrinkage of the conformally coated isolation material layer (i.e., thermal barrier 400) ranges from about 1% to about 4%, about 2% to about 4%, or about 2.5% to about 3.5%.

[0103] The coating weight of the conformal coating 420 does not show a clear trend with regard to its effect on the amount of shrinkage of the coated isolation material layer (i.e., thermal barrier 400). In other words, the heavier conformal coating 420 does not show less shrinkage in the length, width, or thickness of the thermal barrier 400. Example 5 below further demonstrates the effect of the conformal coating 420 on dimension shrinkage of the isolation material layer 110. The coating weight is the weight of coating that is applied divided by the weight of the non-coated isolation material layer 110. For example, the coating weight is 10% if an isolation material layer of 500g is coated with 50g of conformal coating.

[0104] Conformal coating 420 decreases the strain of the isolation material layer 110. In other words, the isolation material layer 110 with conformal coating 420 (i.e., thermal barrier 400) is stiffer than the non-coated isolation material layer 110. The stain of the coated isolation material layer (i.e., thermal barrier 400) is proportional to the coating weight of the conformal coating 420. In one aspect, the strain of the non-coated isolation material layer 110 ranges from about 40 to about 60. about 45 to about 55, or about 47.5 to about 50 at 1 Mpa. For light coating weight of about 10 wt% to about 15 wt%, the strain of the thermal barrier 400 at 1 Mpa ranges from about 40 to about 50, from about 42.5 to about 47.5, or from about 44 to about 46. For medium coating weights of about 15wt% to about 30 wt%, the strain of the thermal barrier 400 at 1 MPa ranges from about 35 to about 50, from about 35 to about 45, or from about 37.5 to about 42.5. For heavy coating weights of about 30 wt% to about 45 wt%, the strain of the thermal barrier at 1 Mpa ranges from about 25 to about 40, from about 27.5 to about 37.5, or from about 30 to about 35. Example 6 below further demonstrates the effect of the conformal coating 420 on strain of the isolation material layer 110.

[0105] The strain of the isolation material layer 1 10 at 1 Mpa is closely related to the density of the thermal barrier 400. The density of the thermal barrier 400 is, in turn, closely related to the coating weight of the conformal coating 420.

[0106] The density of the conformally coated isolation layer (i.e., thermal barrier 400) increases with the increasing weight of the conformal coating 420. The density’ is tested under 0.2 PSI pressure. In one aspect, the density increases linearly as the coating weight increases. In one aspect, the density increases about 1% to about 12% while conformal weight increases from about 10 wt% to about 45wt%. For example, the densityincreases about 1% to about 4% when conformal coating weight increases from about 10 wt% to about 20 wt%; the density increases about 2% to about 5% when conformal coating weight increases from about 15 wt% to about 25 wt%; the density- increases about 4% to about 8.5% when conformal coating weight increases from about 20 wt% to about 35 wt%; and the density increases about 5% to about 12% while the conformal coating weight increases from about 22 wt% to about 45wt%. Example 7 below further demonstrates the effect of the coating weight of the conformal coating 420 on the density of the thermal barrier 400.

[0107] The strain of the conformally coated isolation material layer (i.e., thermal barrier 400) decreases with the increasing density. In other words, the conformally coated isolation material layer 400 becomes stiffer as the density increases. The density is tested under 0.2 PSI. The density of the non-coated isolation material layer 110 ranges from about 0.21 g / cm3to about 0.23 g / cm3, and the strain ranges from about 47.5 to about 50. The strain of the thermal barrier 400 with conformal coating ranges from about 35 to about 50, about 40 to about 45, about 42.5 to about 47.5, while the density is between about 0.21 g / cm3to about 0.26 g / cm3. The strain of the thermal barrier 400 with conformal coating ranges from about 25 to about 45, about 40 to about 45, about 27.5 to about 42.5, while the density is between about 0.24 g / cm3to about 0.31 g / cm3. Example 7 below further demonstrates the effect of the density on the strain of the thermal barrier 400.

[0108] The compression set of the conformally coated isolation material layer (i.e., thermal barrier 400) is similar to the compression set of the non-coated isolation material layer 110. The compression sets for the coated and non-coated isolation material layers 400, 110 range from about 65% to about 98%, from about 75% to about 95%, from about 80% toabout 95%, from about 80% to about 90%, or from about 82.5% to about 90%. In one aspect, the average compression set for non-coated isolation material layer 110 is about 86%, the average compression set for parylene-C coated isolation material layer (one example of thermal barrier 400) is about 84%, and the average compression set for parylene-N coated isolation material layer (another example of thermal barrier 400) is about 88%. Example 8 below further demonstrates the effect of the conformal coating 420 on the compression set of the conformally coated isolation material layers 400.

[0109] Method of the conformal coating

[0110] In one aspect, a process used to form the conformal coating 420 (the coating process) includes at least three steps. The first step is to vaporize a coating source material into a vapor phase. The coating source material may be in a solid state or a liquid state. In one aspect, the coating source material is in solid state. The temperature of the vaporizing step is less than about 200°C. For example, the vaporizing temperature could be less than about 150°C, less than about 100°C, less than about 80°C, or less than about 60°C. In one aspect, the vaporization of the source material is carried out under vacuum. In one aspect, the vaporization of the source material is carried out under a pressure less than about 5 torr, less than about 3 torr, or less than about 1 torr.

[0111] The coating source material may be inorganic compounds, metal-organic complexes, polymers, other suitable coating source materials, or combinations thereof. In one aspect, the coating source material may be a polymer, such as a dimer. In one aspect, the coating source material may be poly(p-xylylene) and its derivatives (e.g., parylene), fluorocarbon polymers (e.g., hexafluoropropylene oxide, polytetrafluoroethylene, polyvinylidene difluoride, perfluorodecanoic acid, poly(lH,lH,2H,2H-perfluorodecyl acrylate)), organosilicon polymers (tetramethylsilane, hexamethyldisilazane, dimethyldichloro-silane), acrylate / methacrylate polymer, sty rene and other vinyl polymers, ring opening polymers, polyamide (e.g.. nylons), polyimide, polyurea, polythiourea, polyurethane, polyester, polyazomethine, other polymers suitable for vapor phase coating, and combinations thereof. In one aspect, the coating source material is a parylene, acrylic, silicone, urethane, other suitable materials, and combinations thereof. In one aspect, the coating source material is a parylene dimer.

[0112] In one aspect, the coating source material is paracyclophane. One example of the coating source material is a dimer named [2,2]para-cyclophane. [2,2]para-cyclophane can be pyrolyzed into monomer p-xylylene, which can be polymerized in situ on the isolation material layer to form the poly(para-xylylene) conformal coating. Poly(para- xylylene) is also referred to as parylene N). Parylene N is a linear material, which is highly crystalline. Parylene N is a primary dielectric, and thus exhibits the following characteristics: a very low dissipation factor, a high dielectric strength, and a low dielectric constant invariant with frequency.

[0113] In one aspect, the coating source material is a dimer named dichloro[2.2]para-cyclophane. Dichloro[2.2]para-cyclophane is also referred to as parylene- C. Parylene C, is produced from the same raw material (dimer) as Parylene N, and is modified by the substitution of a chlorine atom for one of the aromatic hydrogens. The chlorine atom on the benzene ring of parylene C replaces one of the aromatic hydrogen atoms of parylene N, which results a low chemical, moisture, and vapor permeability, making parylene C particularly useful where protection is needed from corrosive gases.

[0114] The second step of the coating process is to pyrolyze the vapor phase coating source material into a monomeric form. The pyrolysis temperature is above 500°C. For example, the pyrolysis temperature may be above 500°C, above 600°C, above 700°C, or above 800°C. In one aspect, the pyrolysis temperature is above 650°C. In one aspect, the temperature of the pyrolysis process is higher than the temperature of the vaporization process of the coating source material. In one aspect, the pyrolysis process of the source material is carried out under vacuum. In one aspect, the pyrolysis of the source material is carried out under a pressure less than about 1 torr, less than about 0.5 torr, or less than about 0.1 torr. In one aspect, the pyrolysis process is carried out at a pressure less than the pressure of the vaporization process.

[0115] The third step of the coating process is to deposit and polymerize the pyrolyzed vapor phase coating source material over the surface of the isolation material layer 110. During the third step, the isolation material layer 110 is exposed to the pyrolyzed vapor phase coating source material. The temperature of the depositing and polymerizing is less than about 100°C, less than about 80°C, less than about 60°C. less than about 40°C, or less than about 20°C. For example, the depositing and polymerizing temperature is less thanabout 40°C. Tn one aspect, the deposition and polymerizing process is performed under vacuum. In one aspect, the temperature of the deposition process is lower than the temperature of the pyrolysis process and the vaporization process. In one aspect, the polymerization process is carried out under a vacuum. In one aspect, the polymerization process is carried out under a pressure less than about 0.5 torr, less than about 0.3 torr, or less than about 0.1 torr. In one aspect, the polymerization process is carried out at a pressure less than the pressure of the pyrolysis process.

[0116] Because the deposition process is in a vapor phase, the vapor will encompass and penetrate surface structures, such as reinforcing structure pores 202. isolation material pores 304, and exposed fibers 406. The vapor phase of the coating monomer is then polymerized to form a polymer coating on the surface structures, such as reinforcing structure pores 202, isolation material pores 304, and exposed fibers 406.

[0117] The third step of the coating process may optionally include a polymerization initiation step. The polymerization initiation step includes, for example, exposure to wave energy, such as ultraviolet light, heat or other initiating energy. Other aspects of the polymerization initiation step include introduction of a chemical initiator during the vaporizing, depositing, and / or polymerizing, for example in gas form.

[0118] In one aspect, at least one of the vaporizing, depositing, and polymerizing process is at a temperature of less than about 150°C, less than about 100°C, less than about 80°C, less than about 50°C, less than about 30°C, or less than about 25°C. In one aspect, all three steps of vaporizing, depositing and polymerizing process are carried out under at a temperature of less than about 150°C, less than about 100°C, less than about 80°C, less than about 50°C, less than about 30°C, or less than about 25°C. The mild temperature required for the coating reduces the cost and risk of the coating process.

[0119] Figure 5 shows one aspect of the full thermal barrier 400’, which is encapsulated in the conformal coating 420. A thickness 502 of the thermal barrier 400’ is shown. In one aspect, the thickness 502 is between about 0. 1 mm to about 50 mm, between about 0.5 mm to about 30 mm, between about 0.5 mm to about 15 mm, between about 0.5 mm to 10 mm, between about 0.5 mm to about 5 mm, between about 0.5 mm to about 1.5 mm. or any ranges between about 0. 1 mm to about 50 mm. Thinner thermal barriers 400' provide more space in a battery module 100. 100’ for the battery cells 102, and reduce anoverall size of a battery module 100, 100’, while still providing thermal barriers for safety. However, as thermal barriers 400’ become thinner, they may become more fragile. Inclusion of the conformal coating 420 disclosed herein allows reduced thickness 502, while maintaining a desired mechanically robust property. This is due, in part, to the fact that the conformal coating 420 is thinner than other types of coatings (e.g., non-conformal coating) or encapsulations (e.g., polymer film encapsulations) while still containing dust of the thermal barrier.

[0120] Figure 5 further shows a penetration depth 504 of the conformal coating 420. The penetration depth 504 is the distance between the exterior surface of the isolation material layer 1 10 and an interior location of the isolation material layer 110 where the coating material can reach. In one aspect, the penetration depth 504 is in a range of about 2 nm to about 2 mm. In other examples, the penetration depth 504 ranges from about 2 nm to about 10 pm, from about 2 nm to about 800 pm, from about 100 nm to 100 pm, from about 1 pm to about 500 pm, from about 150 pm to about 250 pm, from about 10 pm to about 1 mm, or from about 100 pm to about 2 mm. In one aspect, the penetration depth 504 is a function of pore size (e.g., pore sizes of the reinforcing structure pore 202 and / or the isolation material pores 304) in the isolation material layer 110. Factors such as average pore size, and pore size distribution contribute to the penetration depth 504. Further, structures such as exposed fibers 406 have an effect on penetration depth 504. In one aspect, the penetration depth 504 is approximately 5 times, approximately 20 times, approximately 40 times, or approximately 50 times of an average pore diameter. Because longer deposition and / or polymerization times provide thicker coatings on all structures, as deposition and / or polymerization proceeds, an average pore size decreases. As a result, the penetration depth 504 has a limit, and does not significantly increase with longer deposition times.

[0121] The conformal coating 420 may form a continuous film over the isolation material layer 1 10 in some aspects. In one aspect, conformal coating 420 partially covers the isolation material layer 110. In one aspect, the conformal coating substantially covers the isolation material layer 110. In one aspect, the conformal coating 420 encapsulates the entire exterior surfaces of the isolation material layer 110 without exposing the isolation material 302 or the reinforcing network 200, thereby reducing or preventing dust and debrisof the isolation material 302 from detaching from the isolation material layer 110. Tn one aspect, the conformal coating 420 reduces or prevents the uptake of undesired moisture / gas (thermal runaway ejecta) or liquid (e.g., battery electrolyte leakage).

[0122] The conformal coating 420 may extend beyond the exterior surface of the isolation material layer 110. In other words, the coating process forms conformal coating 420 that builds up on the exterior surface of the isolation material layer 110. As show n in Figure 5, the conformal coating 420 has a thickness 505 that is greater than the penetration depth 504. In one aspect, the thickness 505 is less than about 3 mm, 1 mm, 500 pm. 100 pm. 5 pm, less than 3 pm, or less than 1 pm. In one aspect, the thickness 505 is greater than 1 nm, greater than 5 nm, or greater than 10 nm. In one aspect, the thickness 505 ranges from about 2 nm to about 1 pm.

[0123] As discussed above, the ability to form the conformal coating 420 on exterior structures, such as reinforcing structure pores 202, isolation material pores 304, and exposed fibers 406 at or near the outermost surfaces of the isolation material layer 110, without undue penetration into an interior of the isolation material layer 110 has an advantage of preserving thermal insulation properties (by only conformally coating the pores 202, 304 on the surface of the isolation material layer 110) of the isolation material layer 110, and thus the thermal barrier 400, 400’. This is achieved while gaining mechanical robustness and improved adhesion of these structures, which reduces or eliminates dust and debris.

[0124] Figures 6A, 6B, 7A, and 7B illustrate selected close-up aspects of the conformal coatings 420. In Figure 6A, an exposed fiber 604’ of the reinforcing network 200 at the surface of the isolation material layer 1 10 prior to coating is shown. Tn Figure 6B, a number of grains 604 of a conformal coating 420 are coupled to a surface of the exposed fiber 406’ of Figure 6A. The conformal coating 420 is formed by deposition of the grains 604 onto the surface features of the isolation material layer 110. In this manner, the conformal coating 420 follow s the features of the exterior surface of the isolation material layer 110, and in particular of the exposed fibers 406’ and any other exposed surface features of the isolation material layer 110. In one aspect, the grains 604 are substantially crystalline. In one aspect, the grains 604 are partially crystalline. In one aspect, the grains604 are substantially amorphous. The crystalline form may increase the mechanical durability of conformal coating 420 compared to the amorphous form.

[0125] Similarly, Figure 7A shows a porous network 700 of an isolation material 302. The porous network 700 has pores 701. The porous network 700 is, however, not limited to the porous network of the isolation material. For example, the porous network 700 may be part of the porous network of the reinforcing network 200. In one aspect, the porous network 700 includes an aerogel. Figure 7B shows a number of grains 704 of a conformal coating 420, which are coupled to a surface of the porous network 700. The conformal coating 420 contours the exterior surface of the porous network 700 due to the unique combination of the deposition method applied and the properties (pore size, pore size distribution, surface morphology, surface chemical bonds, etc.) of the porous network 700. Similar to the grains 604 in Figure 6B, the grains 704 may include crystalline grains, partially crystalline grains, amorphous grains, or combinations thereof. A degree of crystallinity of the conformal coating 420 can provide one or more of the desired mechanical properties as discussed in aspects above. For example, the crystalline form may increase the mechanical durability of conformal coating 420 compared to the amorphous form.

[0126] Figure 8 shows a flow diagram of a method of manufacture in one aspect. In operation 802, an aerogel material (e.g., fiber reinforced aerogel composite) is formed, the aerogel material having pores, such as the reinforcing network pores 202 and aerogel / isolation material pores 304. In operation 804, the aerogel material is exposed to a vapor phase of a coating monomer. In operation 806, the pores are penetrated to a penetration depth, and in operation 808, the coating monomer is polymerized on the aerogel material to form a conformal coating on aerogel structures between an exterior surface and the penetration depth.

[0127] A thermal barrier (e.g., the isolation material layer with the conformal coating thereon) formed by methods in the present disclosure will exhibit specific, detectable physical differences from thermal barrier formed using other methods. Aspects of physical differences may include a degree of conformality7in the coating, a coating depth, and coating integrity. Thermal and mechanical properties of the thermal barrier with conformal coating may also be improved or maintained relative to thermal barriers beforeconformal coating or thermal barriers with non-conformal coating. Physical properties for given coating dimensions (such as coating thickness and penetration depth) will also be detectable and different from coatings formed by other methods.

[0128] Battery’ modules 100, 100’ and thermal barriers 400, 400’ as described above are used in a number of electronic devices. Figure 9 illustrates an aspect of an electronic device 900 that includes a battery module 100, 100’. The battery module 100, 100’ is coupled to functional electronics 920 by circuitry' 912. In the aspect shown, the battery’ module 100, 100’ and circuitry 912 are contained in a housing 902. A charge port 914 is shown coupled to the battery module 100, 100’ to facilitate recharging of the battery module 100, 100’ when needed.

[0129] In one aspect, the functional electronics 920 include devices such as semiconductor devices with transistors and storage circuits. Aspects include telephones, computers, display screens, navigation systems, etc.

[0130] Figure 10 illustrates another electronic system that utilizes battery modules 100, 100’ that include thermal management systems as described above. An electric vehicle 1000 is illustrated in Figure 10. The electric vehicle 1000 includes a chassis 1002 and wheels 1022. In the aspect shown, each wheel 1022 is coupled to a drive motor 1020. A battery module 100, 100’ is shown coupled to the drive motors 1020 by circuitry 1006. A charge port 1004 is shown coupled to the battery^ module 100, 100’ to facilitate recharging of the battery’ module 100, 100’ when needed.

[0131] Aspects of electric vehicle 1000 include consumer vehicles such as cars, trucks, etc. Commercial vehicles, such as tractors and semi-trucks, are also within the scope of the invention. Although a four wheeled vehicle is shown, other vehicles are contemplated as being within the purview of this disclosure. For example, two wheeled vehicles, such as motorcycles and motorized scooters, are also within the scope of the invention.

[0132] To better illustrate the method and apparatuses disclosed herein, a nonlimiting list of aspects is provided here:

[0133] Aspect 1 includes a battery module. The battery' module comprises a number of cells electrically coupled together and an isolation material layer between at least two cells in the number of cells, the isolation material layer including an outer porous surface. The battery module also includes a conformal coating over the outer porous surface of theisolation material layer, wherein the conformal coating penetrates the outer porous surface of the isolation material layer to a penetration depth in a range of about 2 nm to 800 pm.

[0134] Aspect 2 includes the battery' module of Aspect 1, wherein the conformal coating encapsulates the isolation material layer.

[0135] Aspect 3 includes the battery module of any one of Aspects 1-2, wherein the penetration depth ranges from about 150 pm to about 250 pm.

[0136] Aspect 4 includes the battery' module of any one of Aspects 1-3, wherein the conformal coating is formed from a substantially crystalline material.

[0137] Aspect 5 includes the battery module of any one of Aspects 1-4, wherein the isolation material layer includes an aerogel material with a reinforcing network layer.

[0138] Aspect 6 includes the battery module of any one of Aspects 1-5, and in particular of Aspect 5, wherein the reinforcing network layer includes a polymer foam.

[0139] Aspect 7 includes the battery module of any one of Aspects 1-6, and in particular of Aspect 5, wherein the reinforcing network layer includes a fiber layer.

[0140] Aspect 8 includes the battery module of any one of Aspects 1-7, and in particular of Aspect 5, wherein the aerogel material includes a silica-based aerogel.

[0141] Aspect 9 includes the battery module of any one of Aspects 1-8, and in particular of Aspect 5, wherein the reinforcing network layer is encapsulated by the isolation material layer.

[0142] Aspect 10 includes the battery' module of any one of Aspects 1-9, wherein the conformal coating includes pary lene.

[0143] Aspect 11 includes the battery module of any one of Aspects 1-10. wherein the isolation material layer includes aerogel particles mixed with a carrier.

[0144] Aspect 12 includes a method of forming a thermal barrier, comprising forming an aerogel material, the aerogel material having pores, exposing the aerogel material to a vapor phase of a coating monomer, penetrating the pores with the vapor phase of the coating monomer to a penetration depth, and polymerizing the coating monomer on the aerogel material to form a conformal coating on aerogel structures between an exterior surface and the penetration depth.

[0145] Aspect 13 includes the method of aspect 12, wherein the coating monomer includes a parylene monomer.

[0146] Aspect 14 includes the method of any one of aspects 12-13, wherein forming the aerogel material involves forming the aerogel material at least partially within a reinforcing network.

[0147] Aspect 15 includes the method of any one of aspects 12-14, and in particular Aspect 14, wherein the reinforcing network is a fiber layer network.

[0148] Aspect 16 includes the method of any one of aspects 12-15, and in particular Aspect 14, wherein the reinforcing network is a foam network.

[0149] Aspect 17 includes the method of any one of aspects 12-16, wherein the penetration depth ranges from about 0.5 microns to 1.0 microns.

[0150] Aspect 18 includes the method of any one of aspects 12-17, wherein polymerizing the coating monomer includes polymerizing below about 40°C.

[0151] Aspect 19 includes a thermal barrier. The thermal barrier includes an isolation material layer having pores, and a conformal coating over an exterior surface of the isolation material layer. The conformal coating is formed by a method including exposing the isolation material layer to a vapor phase of a coating monomer, penetrating the pores with the vapor phase of the coating monomer to a penetration depth, and polymerizing the coating monomer on the isolation material layer to form a conformal coating on pore structures between the exterior surface and the penetration depth.

[0152] Aspect 20 includes the thermal barrier of aspect 19, wherein the penetration depth ranges from about 0.5 microns to 1.0 microns.

[0153] Aspect 21 includes the thermal barrier of any one of aspects 19-20, wherein the isolation material layer includes aerogel particles mixed with a carrier.

[0154] Aspect 22 includes the thermal barrier of any one of aspects 19-21 , wherein the isolation material layer at least partially penetrates a reinforcing network layer.

[0155] The above description is intended to be illustrative, and not restrictive. In one aspect, the above-described aspects (or one or more aspects thereof) may be used in combination with each other. Other aspects can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, variousfeatures may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed aspect. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate aspect, and it is contemplated that such aspects can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0156] Although an overview of the inventive subject matter has been described with reference to specific aspects, various modifications and changes may be made to these aspects without departing from the broader scope of aspects of the present disclosure. Such aspects of the inventive subject matter may be referred to herein, individually or collectively, by the term "invention'’ merely for convenience and without intending to voluntarily limit the scope of this application to any single disclosure or inventive concept if more than one is, in fact, disclosed.

[0157] The aspects illustrated herein are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed. Other aspects may be used and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. The Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of various aspects is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled.

[0158] As used herein, the term "or” may be construed in either an inclusive or exclusive sense. Moreover, plural instances may be provided for resources, operations, or structures described herein as a single instance. Additionally, boundaries between various resources, operations, modules, engines, and data stores are somewhat arbitrary, and particular operations are illustrated in a context of specific illustrative configurations. Other allocations of functionality are envisioned and may fall within a scope of various aspects of the present disclosure. In general, structures and functionality presented as separate resources in the aspect configurations may be implemented as a combined structure or resource. Similarly, structures and functionality’ presented as a single resource may be implemented as separate resources. These and other variations, modifications, additions,and improvements fall within a scope of aspects of the present disclosure as represented by the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

[0159] The foregoing description, for the purpose of explanation, has been described with reference to specific aspects. However, the illustrative discussions above are not intended to be exhaustive or to limit the possible aspects to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The aspects were chosen and described in order to best explain the principles involved and their practical applications, to thereby enable others skilled in the art to best utilize the various aspects with various modifications as are suited to the particular use contemplated.

[0160] It will also be understood that, although the terms “first,’’ “second,” and so forth may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For aspect, a first contact could be termed a second contact, and, similarly, a second contact could be termed a first contact, without departing from the scope of the present aspects. The first contact and the second contact are both contacts, but they are not the same contact.

[0161] The terminology used in the description of the aspects herein is for the purpose of describing particular aspects only and is not intended to be limiting. As used in the description of the aspects and the appended aspects, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and / or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0162] As used herein, the term “if’ may be construed to mean “when” or “upon” or “in response to determining” or “in response to detecting,” depending on the context. Similarly, the phrase “if it is determined” or “if [a stated condition or event] is detected” may be construed to mean “upon determining” or “in response to determining” or “upondetecting [the stated condition or event]” or "in response to detecting [the stated condition or event],” depending on the context.EXEMPLIFICATION

[0163] The present invention may be further illustrated by the following nonlimiting examples describing the thermal barrier properties before and / or after conformal coating / encapsulating. The following examples are described for illustrative purposes only and are not intended to be limiting the scope of the various embodiments of the current invention in any way.Example 1: Impact of parylene coating / encapsulation on BET surface area

[0164] Two types of parylene, parylene-C and parylene-N, were conformally coated to isolation material layers. The isolation material layers were fiber reinforced silica aerogels. A solid state parylene source material was vaporized into a vapor phase at 150°C in a vaporizer. The vapor was pyrolyzed in a pyrolysis chamber at 680°C. The pyrolyzed vapor was introduced to a coating chamber where the isolation material layer was exposed in the pyrolyzed vapor phase parylene. A typical temperature of the coating chamber ranges from about 20°C to about 35°C (e.g., 25°C, 30°C, etc.). The isolation material layer did not need to be heated. The pyrolyzed vapor was conformally coated on the surface of the isolation material layer, including the fibers of the reinforcing structure, surface pores of the aerogel material, and the structural pores of the reinforcing structure. A typical non-coated isolation material layer has a thickness of about 2.46 mm, size of about 0.0261 m2, a weight of about 535 g / m2, and a density of about 0.2134 g / cm3prior to coating / encapsulating. The coating weight ranged from about 50 g / m2to about 400 g / m2. An example of a heavy coating weight is about 364 g / m2. The coating weight is the weight of coating applied divided by the weight of the non-coated isolation material layer. For example, the coating weight is 10% if an isolation material layer of 500g is coated with 50g of conformal coating.

[0165] Different coating weights of parylene-C and parylene-N were obtained by controlling the process parameters until the designed coating weight in Table 1 was reached. The major process control parameters included the deposition time and the amount ofcoating source material (e.g., dimers) charged to the coating system. Other process parameters to control the coating weight may include vacuum level, isolation material layer temperature, pyrolysis temperature, and the properties (e.g., porosity , pore structure, composition) of the isolation materials.

[0166] As shown in Table 1, the parylene coated isolation material layers had lower BET surface area than non-coated isolation material layers. The non-coated isolation material layers had BET surface areas ranging from about 270 m2 / g to about 325 m2 / g. Both the parylene-C and parylene-N coated isolation material layers demonstrated lower BET surface areas, ranging from about 95 m2 / g to about 255 m2 / g. The BET surface area decreased with the increasing coating weights regardless of the type of coating used (i.e., parylene-C or parylene-N). With coating weights between 11 wt% to 15 wt%, the BET surface areas were above 200 m2 / g. The BET surface areas were in the 100 m2 / g to 200 m2 / g range with coating weights between 15 wt% to 35 wt%. The BET surface areas were below 100 m2 / g when the coating weights were around 40%.

[0167] The normalized BET surface area was calculated based on the weight of the isolation material layer only without considering the weight of the conformal coatings. The normalized BET surface areas of the isolation material layers ranged from 130 m2 / g to 400 m2 / g. Isolation material layers with less than about 15% coating had a BET surface area range similar to the BET surface area range of the non-coated isolation material layers. In other words, selected coating weight and ty pe of coating material do not reduce the normalized BET surface area of the isolation material layers. For example, the 12.38% parylene-C coated isolation material layer showed a normalized BET surface area of 386.06 m2 / g.Table 1.BET surface area of conformally coated isolation material layer„„rNormalized BET„ Coating BET surface areaCoating ChemistryP, , , surface areaIm / gl[m7glParylene-N (Light) 32.86% 125.1584 186.41Parylene-N (Light) 28.27% 173.9628 242.54Parylene-N (Light) 26.53% 226.0985 307.74Parylene-N (Light) 27.45% 218.4863 301.15Parylene-N (Light) 20.81% 250.7413 316.63Parylene-N (Light) 27.97% 197.3277 273.95Parylene-C (Light) 16.27% 196.5790 234.78Parylene-C (Light) 18.39% 196.7262 241.05Parylene-C (Light) 13.23% 220.5034 254.12Parylene-C (Light) 11.90% 224.9477 255.33Parylene-C (Light) 12.38% 338.2677 386.06Parylene-C (Light) 12.09% 254.7867 289.83Parylene-N (Heavy) 41.49% 99.9258 170.78Parylene-N (Heavy) 39.65% 95.9094 158.93Parylene-N (Heavy) 32.26% 178.3433 263.28Parylene-N (Heavy) 39.57% 166.7068 275.87Parylene-N (Heavy) 34.70% 187.6666 287.39Parylene-N (Heavy) 31.72% 199.0694 291.55Parylene-C (Heavy) 23.03% 102.5265 133.20Parylene-C (Heavy) 25.63% 168.4268 226.46Parylene-C (Heavy) 15.36% 209.1659 247.12Parylene-C (Heavy) 22.31% 186.4046 239.93Parylene-C (Heavy) 23.43% 229.6044 299.86Parylene-C (Heavy) 15.92% 227.4969 270.57Uncoated Control 0.00% 274.0663 274.07Uncoated Control 0.00% 307.4050 307.41Uncoated Control 0.00% 288.5490 288.55Uncoated Control 0.00% 281.1033 281.10Uncoated Control 0.00% 321.8333 321.83Uncoated Control 0.00% 277.9228 277.92Uncoated Control 0.00% 266.5698 266.57Uncoated Control 0.00% 279.4705 279.47Example 2: Impact of coating / encapsulation on thermal conductivity

[0168] Two types of parylene, namely parylene-C and parylene-N, were each conformally coated over isolation material layers by two coating weights (light and heavy as shown in Table 2) according to the method in example 1. The isolation material layers were fiber reinforced silica aerogels.

[0169] Each of the four groups (light parylene-C, heavy parylene-C. light parylene- N, heavy parylene-N) included 32 duplicated samples. The maximum, minimum, and average values of the 32 duplicated samples in each of the 4 groups are listed in Table 2. The mean coating w eight of the light parylene-C coated samples w as about 14.18%, which correlated to about 42.93 g / m2per each side of the isolation material layer. The meancoating weight of the heavy parylene-C coated samples was about 19.51 %, which correlated to about 65.93 g / m2per each side of the isolation material layer. The mean coating weight of the light parylene-N coated samples was about 25.35%, which correlated to about 91.12 g / m2per each side of the isolation material layer. The mean coating weight of the heavy parylene-N coated samples was about 33.18%, which correlated to about 134.83 g / m2per each side of the isolation material layer.Table 2.

[0170] The effect of the parylene coating on the thermal conductivity of the isolation material layer shown in Table 2 are plotted in Figure 11. The thermal conductivity (Tc) of each sample was measured both before and after coating. The y-axis is the difference between the Tc of the coated isolation material layer and the Tc of the same isolation material layer prior to coating. All isolation material layers show positive value on the y-axis meaning that all samples experienced an increased Tc due to the application of the coating. The x-axis represents the average Tc before and after coating. As the coat weight percentages increased, the y-axis values moved in the direction from lower left to upper right of the graph (both the difference and the average Tc measurements increased as a function of coat weight applied). This test indicates that there was a statistically significant increase in Tc as a function of the coating application.

[0171] For example, light Parylene-C coating slightly increased the conductivity of the isolation material layer by about 1.5 mW / m-K to about 2.5 mW / tn-K, while the heavyParylene-C coating further increased the conductivity of the isolation material layers by about 2 mW / m-K to about 2.75 mW / m-K. In comparison, parylene-N caused more of a thermal conductivity increases compared to the parylene-C coating. For light parylene-N coating weight samples, thermal conductivity increased about 2.5 mW / m K to about 5 mW / m-K. For heavy parylene-N coating weight, thermal conductivity increased about 2.75 mW / m-K to about 9 mW / m-K.Example 3: Impact of coating / encapsulation on heat of combustion

[0172] Parylene-C and parylene-N coated isolation material layers were prepared according to the method disclosed in Example 1 until the coating weights in Table 3 were achieved. The isolation material layers were fiber reinforced silica aerogels. The samples shown in Table 3 were analyzed for HoC and the results are shown Figures 12 and 13.

[0173] The HoC values w ere tested using oxygen bomb calorimeter. Each of the non-coated isolation material layers was pulverized using a rotary '‘swing mill” grinder, until the ground samples were less than 60 mesh. The ground samples were compressed into a pellet thereafter for HoC tests. The conformally coated isolation material layers were compressed into a pellet without milling. This is because the conformal coating binds the components of the isolation material layers together such that the grinder was not able to pulverize the conformally coated isolation material layers.Table 3. Impact of coating on HoC of the parylene-C and parylene-N coated isolation material layers

[0174] Figure 12 illustrates the heat of combustion values at different coating weights (where the sample from Table 3 is identified with its coating weight). The two heat isolation material layers without parylene coating had HoC of 1062 cal / g and 1000 cal / g. The HoC of the coated / encapsulated isolation material layer was proportional with the parylene coating amount as shown in Figure 12. The HoC of the isolation material layers was between 1500 cal / g to 4500 cal / g with coating weights that ranged from about 10 wt% to about 40 wt%.

[0175] Figure 13 illustrates the impacts of different types of parylene coating on the HoC of the isolation material layer. Parylene-C coating / encapsulation slightly increased the HoC from an average of about 1000 cal / g to an average of about 1800 cal / g. Parylene-N coating / encapsulation increased the HoC to an average of about 3100 cal / g. The greater increase in the HoC of parylene-N coated isolation material layers was likely due to the higher coating weight compared to the parylene-C coated isolation material layers. As shown in Table 3, the parylene C coating weights ranged from about 10 wt% to about 20 wt%, while the parylene-N coating weights ranged from about 15wt% to about 40wt%.Example 4; Impact of coating / encansulation on TGA and DSC

[0176] Parylene-C and parylene-N coated isolation material layers were prepared according to the method disclosed in Example 1 until the coating weights in Table 4 were achieved. The isolation material layers were fiber reinforced silica aerogels. The TGA test and the DSC test were performed on the respective samples listed in Table 4. The weight loss (from the TGA test), heat release (from the DSC test), onset temperature (from the DSC test), and peak temperature (from the DSC test) results are respectively shown in Figures 14-17.

[0177] Figure 14 and Table 4 illustrate the weight / mass loss of the parylene-C and parylene-N coated isolation material layer during TGA testing. The average weight loss of the tested coated isolation material layers (thermal barriers) corresponded to the coating weights. The average weight loss of the non-coated isolation material layer was about 5.5%. The parylene-C samples having a coating weight that ranged from about 10%-20% (see Table 4) had an average weight loss of about 18%. The parylene-N samples having a coating weight that ranged from about 25%-40% (see Table 4) had an average weight loss of about 35%.

[0178] Figure 15 illustrates the heat release of the parylene-C and parylene-N coated isolation material layer during DSC testing. Table 4 illustrates the heat release of the parylene-C and parylene-N coated isolation material layer during DSC testing. The average heat release of the coated isolation material layer corresponded to the coating weights. The average heat release of the non-coated isolation material layer was about 500 J / g. The parylene-C samples having a coating weight that ranged from about 10%-20% (see Table 4) had an average heat release of about 2000 J / g. The parylene-N samples having a coating weight that ranged from about 25%-40% (see Table 4) had an average heat release of about 3750 J / g.Table 4

[0179] Figures 16 and 17 illustrate the onset temperature and peak temperature, respectively, of the parylene-C and parylene-N coated isolation material layer respectively during DSC testing. Table 4 illustrates the onset temperature and peak temperature, respectively, of the parylene-C and parylene-N coated isolation material layer during DSC testing. Both the parylene-C and parylene-N coated samples demonstrated lower onset temperature at about 250°C as show n in Figure 16, compared to the onset temperature of about 550°C for the non-coated isolation material layer. Different from the weight loss and heat release results, the onset temperature and peak temperature were independent from the coating types and coating weights. In other words, the onset temperature and the peak temperature were not affected by coating types and coating weights. The isolation material layers with different types of coating and with different coating weights showed similaronset temperature and peak temperature statistically, compared to the non-coated isolation material layer.Example 5: Impact of coating / encapsulating on shrinkage of the isolation material layer

[0180] Parylene-C and parylene-N coated isolation material layers were prepared according to the method disclosed in Example 1 until the coating weights in Table 5 were achieved. The isolation material layers were fiber reinforced silica aerogels.

[0181] The coated and non-coated isolation material layers were subject to a hot surface test. Shrinkages of the coated and non-coated isolation material layers represent the differences in length, width, and thickness before and after the hot surface test. In a hot surface test, an isolation material layer is placed on a hot surface. A hot wall of an oven was used in this example. The hot surface temperature was ramped to about 950°C or more at a ramp rate of about 35°C / min. The temperature of the isolation material layer was about 930°C + 10°C on the opposite side of the hot surface.Table 5.Shrinkage of parylene-C and parylene-N coated isolation materialSample ID Parylene % Coating L-Shrink W-Shrink Tks-ShrinkJ PG-341- 23-M25 C (light) 13.25% 2.39% 3.16% 6.11%JPG-341- 23-S17 C (light) 14.38% 2.65% 3.21% 6.17%J PG-341- 24-M14 C (heavy) 18.72% 2.37% 3.40% 4.30%JPG-341- 24-S11 C (heavy) 20.98% 3.88% 3.13% 6.64%JPG-341-23-S3 N (light) 22.52% 2.91% 2.87% 5.26%JPG-341-23-M2 N (light) 24.58% 3.00% 3.38% 0.53%J PG-341- 24-M27 N (heavy) 29.04% 3.48% 2.93% 4.17%J PG-341- 24-S23 N (heavy) 29.19% 2.76% 2.08% 9.99%SI Control None 0.00% 5.07% 3.98% 9.12%M2 Control None 0.00% 3.15% 2.55% 10.97%

[0182] Figure 18 illustrates the dimension shrinkage of the non-coated, parylene-C, and parylene-N coated isolation material layers listed in Table 5. Both parylene-C and parylene-N coated isolation material layer showed less shrinkage compared to the noncoated isolation material layer. The coating weight was about 13% to 30% as listed in Table 5. The thickness shrinkage of the non-coated isolation material was about 9% to 10% of the original thickness before hot surface testing. The parylene coated isolation material layersshowed a thickness shrinkage of about 0.53% to about 9.99% of the original thickness before hot surface test, while the coating w eight of the samples ranged from about 13 wt% to about 30 wt%. The pary lene coatings also reduced the shrinkage in length and width, but the percentage of shrinkage reduction in length and width were less than the percentage of shrinkage in the thicknesses.Example 6: Impact of coating / encapsulation on strain of the isolation material layer

[0183] Parylene-C and parylene-N coated isolation material layers were prepared according to the method disclosed in Example 1 until the coating weights in Table 6 were achieved. The isolation material layers were fiber reinforced silica aerogels.Table 6.Compression set of of the paryl ene-C and paryl ene-N coated isolation material laye rsSample ID Pa rylene Type CoatWeight % Coating 0.2 psi tks [mm] Strain @ 1 Mpa Compressi on Set (%)JPG-341-23-M5 N Medium 24.22% 2.88 39.61 5.17%JPG-341-23-M5 N Medium 24.22% 2.80 39.51 10.88%JPG-341-23-M5 N Med ium 24.22% 2.95 40.75 11.48%JPG-341-23-M9 N Medium 27.23% 2.53 37.79 20.83%JPG-341-23-M9 N Medium 27.23% 2.62 36.28 16.32%JPG-341-23-M9 N Medium 27.23% 2.71 37.81 15.59%JPG-341-23-M 13 N Med ium 20.68% 2.43 43.05 19.55%JPG-341-23-M 13 N Medium 20.68% 2.45 41.79 -21.37%JPG-341-23-M 13 N Medium 20.68% 2.59 42.16 17.25%JPG-341-23-M 18 C Light 14.40% 2.57 42.54 12.55%JPG-341-23-M 18 C Light 14.40% 2.34 47.65 14.99%JPG-341-23-M20 C Light 14.87% 3.14 47.18 7.00%J PG-341-23-S5 N Medium 26.53% 2.61 29.67 31.07%J PG-341- 23- S14 N Medium 23.67% 2.53 38.00 40.80%J PG-341-23- S25 C Light 11.90% 2.70 43.51 21.83%J PG-341-23- S31 C Light 12.78% 2.51 41.92 22.83%JPG-341-24-M1 C Medium 23.43% 2.42 45.16 14.97%JPG-341-24-M 12 C Medium 17.02% 2.78 39.80 13.93%JPG-341-24-M 18 N Heavy 34.70% 2.94 28.98 14.91%JPG-341-24-M32 N Heavy 35.65% 2.82 33.05 19.52%J PG-341- 24- S13 C Medium 22.31% 2.86 43.55 30.50%J PG-341-24- S16 C Light 19.10% 2.95 45.18 31.70%J PG-341-24- S19 N Heavy 29.81% 2.71 33.26 24.06%J PG-341-24- S30 N Heavy 31.03% 3.18 35.45 29.00%J PG-341-50-S1 N / A None 0.00% 3.17 48.77 38.39%J PG-341-50-S2 N / A None 0.00% 2.57 48.86 36.02%JPG-341-50-M2 N / A None 0.00% 2.13 49.12 7.34%JPG-341-50-M3 N / A None 0.00% 2.26 48.62 12.44%

[0184] Figure 19 illustrates the strain of non-coated, parylene-C, and parylene-N coated isolation material layers. Light coating weights were less than 20 wt%. medium coating weights ranged from about 20 wt% to less than 28 wt%. and heavy coating weightsare greater than 28 wt%. Regardless of the coating type being parylene-C or parylene-N, the strain decreased as the coating weight increased. In other words, increasing coating weights caused the isolation material layer to be stiffer. The isolation layer without coating demonstrated an average strain of about 48.8%. The average strain reduced to about 44.7% for light coating, to about average 39.6% for medium coating, and to an average of about 32.7% for heavy coating. The strain values in this example were measured using a pressure of 1 MPa. For example, if a 2 mm sample was compressed down to 1 mm when a force of 1 MPa is applied, the strain rate achieved is 50%.Example 7; Impact of coating / encapsulating on density increase of the isolation material layer

[0185] Parylene-C and parylene-N coated isolation material layers were prepared according to the method disclosed in Example 1 until the coating weights in Table 7 were achieved. The isolation material layers were fiber reinforced silica aerogels.

[0186] Figure 20 illustrates the density increase of the isolation material layers according to the increase of the pary lene coating amount. The density of the coated isolation material layer increased with the increased coating weights. As the coating weights increased from about 10 wt% to about 45 wt%, the density of the coated isolation material layer increased from about 0.01 g / cm3to about 0.12 g / cm3. The coating density was proportional to the coating weight. The linear fit of the increase of the density to the coating weights is represented by :Density increase = —0.022276 + 0.3112922 X percentage of coating weight

[0187] Figure 21 illustrates the correlation between the strain values and the densities of the uncoated. parylene-C, and parylene-N coated isolation material layers of this Example.

[0188] As shown in Figure 21, the density of the uncoated isolation material layers ranged about 0.21 g / cm3to about 0.23 g / cm3. The strain was tested under 1 Mpa pressure. The density was tested under 0.2PSI. Both the densities of the parylene-C and parylene-N coated isolation material layers were increased compared to the density of the non-coatedisolation material layers. The density increase of the isolation material layers was proportional to the coating weights of the parylene-C or parylene-N. Regardless of the types of coating, i.e., parylene-C or parylene-N, the strain at 1 MPa showed a strong correlation with the densities of the coated isolation materials. The higher the density, the lower the strain of the isolation material layer. In other words, the higher the density, the stiffer the isolating material layer.Table 7Strain of the parylene-C and parylene-N coated isolation material layersCoating type coating weight % Strain @ 1 MPa tks @ 1 MpaParylene-N (Light) 24.22% 39.6094 1.7365Parylene-N (Light) 24.22% 39.5068 1.6965Parylene-N (Light) 24.22% 40.7513 1.7465Parylene-N (Light) 27.23% 37.7873 1.5762Parylene-N (Light) 27.23% 36.2755 1.6669Parylene-N (Light) 27.23% 37.8099 1.6865Parylene-N (Light) 20.68% 43.0465 1.3865Parylene-N (Light) 20.68% 41.7851 1.4269Parylene-N (Light) 20.68% 42.1565 1.4973Parylene-C (Light) 14.40% 42.5429 1.4765Parylene-C (Light) 14.40% 47.6512 1.2265Parylene-C (Light) 14.87% 47.1752 1.6565Parylene-N (Light) 26.53% 29.6698 1.8365Parylene-N (Light) 23.67% 38.0033 1.5665Parylene-C (Light) 11.90% 43.5128 1.5269Parylene-C (Light) 12.78% 41.9189 1.4569Parylene-C (Heavy) 23.43% 45.1574 1.3265Parylene-C (Heavy) 17.02% 39.7996 1.6762Parylene-N (Heavy) 34.70% 28.9764 2.0865Parylene-N (Heavy) 35.65% 33.0495 1.8865Parylene-C (Heavy) 22.31% 43.545 1.6165Parylene-C (Heavy) 19.10% 45.18 1.6165Parylene-N (Heavy) 29.81% 33.262 1.8065Parylene-N (Heavy) 31.03% 35.4517 2.0554Example 8; Impact of coating / encapsulation on compression set of the isolation material layer

[0189] Parylene-C and parylene-N coated isolation material layers were prepared according to the method disclosed in Example 1 until the coating weights in Table 8 were achieved. The isolation material layers were fiber reinforced silica aerogels.

[0190] Figure 22 illustrates the compression set of the parylene-C and parylene-N coated isolation material layer compared to the non-coated isolation material layer. The non-coated isolation material layers had an average compression set of about 86% (x-axis N / A), while the average compression sets of the parylene-C and parylene-N coated isolation material layer were about 84% and about 88%, respectively. Statistically, the impact of the parylene coating on the compression set of the isolation material layer was minimal. For example, the parylene-N coating increased the compression set of the isolation material layers by about 2% of the original compression set of the isolation material layers.Table 8.Compression set of of the parylene-C and parylene-N coated isolation material layersMass Coating Starting Tks Starting DensitySample ID Coating Type Compression Set[g] [%] [0.2psi] [0.2 psi]JPG-341-23-S9 1.5 N 27.45% 2.60 0.285 92.82%JPG-341-23-S9 1.57 N 27.45% 2.72 0.285 95.51%JPG-341-23-S9 1.58 N 27.45% 2.80 0.279 98.20%JPG-341-23-S19 1.17 C 13.23% 2.58 0.224 74.94%JPG-341-23-S19 1.25 C 13.23% 2.59 0.238 88.81%JPG-341-23-S19 1.2 C 13.23% 2.58 0.229 82.21%JPG-341-24-S7 1.43 C 18.11% 3.13 0.226 94.36%JPG-341-24-S7 1.57 C 18.11% 3.24 0.239 94.18%JPG-341-24-S16 1.26 C 19.10% 2.62 0.237 69.49%JPG-341-24-S25 2.21 N 36.66% 3.47 0.314 82.68%JPG-341-24-S25 2.19 N 36.66% 3.34 0.324 79.57%JPG-341-24-S25 2.01 N 36.66% 3.27 0.303 87.86%JPG-341- 50-S2 1.1 N / A 0.00% 2.62 0.207 90.08%JPG-341- 50-S3 0.97 N / A 0.00% 2.20 0.217 83.17%JPG-341- 50-S3 1.07 N / A 0.00% 2.33 0.226 85.16%Example 9; Impact of aerogel sintering and coating / encapsulation on compression set of the isolation material layer

[0191] Parylene-C and parylene-N coated isolation material layers were prepared according to the method disclosed in Example 1 until the coating weights in Table 9 were achieved. The isolation material layers were fiber reinforced silica aerogels that were exposed to additional sintering during their formation.

[0192] Figure 23 illustrates the compression set of the parylene-C and parylene-N coated isolation material layers compared to the non-coated isolation material layer. The non-coated isolation material layers had an average compression set of about 10% (x-axis N / A), while the average compression sets of the parylene-C and parylene-N coated isolationmaterial layer were about 16% and about 42%, respectively. The additional sintering of the aerogel material had a relatively significant impact on the compression set.Table 9.Example 10: Impact of coating / encapsulation on dust of the isolation material layer

[0193] Multiple parylene-C and parylene-N coated isolation material layers were prepared according to the method in Example 1. The average values of the sample characterizations were listed in Table 10. The isolation material layers were fiber reinforced silica aerogels.

[0194] Figure 24 illustrates the dust of the parylene-C and parylene-N coated isolation material layers. The dust amount from the uncoated and conformally coated isolation material layers was measured by a DustTrak™ from DRX. The DustTrak™ had a 2 to 3-inch hose placed over its pump’s inlet port. A slight vacuum was created at the inlet to the hose when the DustTrak™ was turned on. The hose was slowly “rastered” back and forth over the isolation material layer for a set period of time (2 minutes). A consistent height of a few millimeters over the isolation material layer was maintained while rastering the hose back and forth. 6 background check tests were done by rastering the hose in air without any sample.

[0195] The 7 non-coated isolation material layers had a mean dust amount of about 8.73 mg / m3. The 6 background check tests showed a mean dust amount of 0.02 without any samples in the background. The two parylene C conformal coating with 12.25 wt% and37.28 wt% coating weight reduced the dust amount to 1.08 mg / m3and 0.657 mg / m3, respectively. The three parylene N conformally coated isolation material layers with 13.93 wt%, 31.01 wt%, and 29.66 wt% coating weight reduced the dust amount to 0.009 mg / m3, 0.074 mg / m3, and 1.46 mg / m3, respectively. The parylene N coatings were heavier than the parylene-C coatings, which lead to a lower mean dust amount of 0.51 mg / m3for parylene-N coated isolation material layers compared to the mean dust amount of 0.87 mg / m3for parylene-C coated isolation material layers (see Table 11).Table 10.Table 11.Mean dust amountDustSamples description3[mg / m ]Parylene-N 0.51Parylene-C 0.87Uncoated 8.73 background check 0.02

[0196] It is to be understood that the ranges provided herein include the stated range and any value or sub-range within the stated range, as if such values or sub-ranges were explicitly recited. For example, a range of from about 10% to about 30% should be interpreted to include not only the explicitly recited limits of about 10% to about 30%, but also to include individual values, such as about 12%, about 15.5%, 27%, etc., and subranges, such as from about 10% to about 15%, from about 14% to about 28%, etc. Furthermore, when “about" and / or “substantially” are / is utilized to describe a value, they are meant to encompass minor variations (up to + / - 10%) from the stated value.

[0197] While several aspects have been described in detail, it is to be understood that the disclosed aspects may be modified. Therefore, the foregoing description is to be considered non-limiting.

Claims

What is claimed is:

1. A battery module, comprising: a number of cells electrically coupled together; an isolation material layer between at least two cells in the number of cells, the isolation material layer including an outer porous surface; and a conformal coating over the outer porous surface of the isolation material layer, wherein the conformal coating penetrates the outer porous surface of the isolation material layer to a penetration depth in a range of about 2 nanometers to about 2 mm.

2. The battery module of claim 1, wherein the conformal coating encapsulates the isolation material layer.

3. The battery module of claim 1, wherein the penetration depth ranges from about 150 microns to about 250 microns.

4. The battery module of claim 1, wherein the conformal coating is formed from a substantially crystalline material.

5. The battery module of claim 1, wherein the isolation material layer includes an aerogel material with a reinforcing network layer.

6. The battery module of claim 5, wherein the reinforcing network layer includes a polymer foam.

7. The battery module of claim 5, wherein the reinforcing network layer includes a fiber layer.

8. The battery module of claim 5, wherein the aerogel material includes a silica-based aerogel.

9. The battery module of claim 5, wherein the reinforcing network layer is partially covered by the isolation material layer.

10. The battery module of claim 1, wherein the conformal coating includes parylene.

11. The battery module of claim 1, wherein the isolation material layer includes aerogel particles mixed with a carrier.

12. A method of forming a thermal barrier, comprising: forming an aerogel material, the aerogel material having pores; exposing the aerogel material to a vapor phase of a coating monomer; penetrating the pores with the vapor phase of the coating monomer to a penetration depth; and polymerizing the coating monomer on the aerogel material to form a conformal coating on aerogel structures between an exterior surface of the aerogel material and the penetration depth.

13. The method of claim 12, wherein the coating monomer includes a parylene monomer.

14. The method of claim 12, wherein forming the aerogel material involves forming the aerogel material at least partially within a reinforcing network.

15. The method of claim 14, wherein the reinforcing network is a fiber layer network.

16. The method of claim 14, wherein the reinforcing network is a foam network.

17. The method of claim 12, wherein the penetration depth ranges from about 2 nanometers to about 2 mm.

18. The method of claim 12, wherein polymerizing the coating monomer includes polymerizing below about 40°C.

19. A thermal barrier, comprising: an isolation material layer having pores; and a conformal coating over an exterior surface of the isolation material layer, the conformal coating formed by a method including: exposing the isolation material layer to a vapor phase of a coating monomer; penetrating the pores with the vapor phase of the coating monomer to a penetration depth; and polymerizing the coating monomer on the isolation material layer to form a conformal coating on pore structures between the exterior surface and the penetration depth.

20. The thermal barrier of claim 19, wherein the penetration depth ranges from about 2 nanometers to about 2 mm.

21. The thermal barrier of claim 19, wherein the isolation material layer includes aerogel particles mixed with a carrier.

22. The thermal barrier of claim 19. wherein the isolation material layer at least partially penetrates a reinforcing network layer.

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