Compressed battery thermal barrier and method

Abstract

Multilayer thermal barriers, battery modules, and related methods are disclosed. In one example, the elastic layer of the multilayer thermal barrier is sized to a footprint substantially the same size as a lithium-ion pouch cell. A configuration is shown in which the thermal insulating layer extends laterally beyond the footprint.

Description

[Technical Field]

[0001] Priority claims This application claims the benefit of priority to U.S. Patent Application No. 63 / 426,304, filed November 17, 2022, which is incorporated herein by reference in its entirety.

[0002] Technical Field The present disclosure generally relates to materials, systems, and methods for preventing or mitigating thermal events, such as thermal runaway problems, in energy storage systems. In particular, the present disclosure provides thermal barrier materials. The present disclosure further relates to battery modules or packs having one or more battery cells that include the thermal barrier material, as well as systems that include these battery modules or packs. Examples generally described may include aerogel materials. [Background technology]

[0003] Lithium-ion batteries (LIBs) are widely used in powering portable electronic devices such as mobile phones, tablets, laptops, power tools, and other high-current devices such as electric vehicles because of their high operating voltage, low memory effect, and high energy density compared to conventional batteries. However, safety concerns have arisen due to the susceptibility of LIBs to catastrophic failure under "abuse conditions," such as when rechargeable batteries are overcharged (charged beyond their design voltage), overdischarged, or operated or exposed to high temperatures and pressures. Summary of the Invention

[0004] Effective insulation and heat dissipation strategies are needed to address these and other technical challenges in LIBs to prevent the occurrence of cascading thermal runaway events. [Brief explanation of the drawings]

[0005] [Figure 1A] 1A-1C illustrate side views of selected portions of a battery module, according to some exemplary embodiments. [Figure 1B] 1A-1C illustrate top views of selected portions of a battery module, according to some exemplary embodiments. [Figure 2A] 1 illustrates a side view of a selected portion of a multi-layer thermal barrier, according to some exemplary embodiments. [Figure 2B] 1 illustrates a side view of a selected portion of a multi-layer thermal barrier, according to some exemplary embodiments. [Figure 2C] 1 illustrates a side view of a selected portion of a multi-layer thermal barrier, according to some exemplary embodiments. [Figure 2D] 1 illustrates a side view of a selected portion of a multi-layer thermal barrier, according to some exemplary embodiments. [Figure 2E] 1A-1C illustrate side views of selected portions of a battery module, according to some exemplary embodiments. [Figure 2F] 1A-1C illustrate side views of selected portions of a battery module, according to some exemplary embodiments. [Figure 3A] 1 illustrates a side view of a selected portion of a multi-layer thermal barrier, according to some exemplary embodiments. [Figure 3B] 1 illustrates a side view of a selected portion of a multi-layer thermal barrier, according to some exemplary embodiments. [Figure 3C] 1 illustrates a side view of a selected portion of a multi-layer thermal barrier, according to some exemplary embodiments. [Figure 4] 1 illustrates a flow diagram of a method according to some exemplary aspects. [Figure 5] 1 illustrates an electronic device according to some example aspects. [Figure 6] 1 illustrates an electric vehicle in accordance with some exemplary embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0006] Description of Aspects The following description and drawings sufficiently describe particular embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in or substituted for other embodiments. Aspects set forth in the claims encompass all available equivalents of those claims.

[0007] overview The present disclosure is directed to a battery module with a multi-layer thermal barrier. The multi-layer thermal barrier includes at least a thermal insulation layer to prevent fire / heat propagation in extreme situations such as thermal runaway. The multi-layer thermal barrier may optionally include an elastic layer and a thermally conductive layer. The elastic layer is for accommodating volumetric changes of the battery cells. The conductive layer is for better regulating the flow of heat generated by the battery cells and protecting the thermal insulation layer from particle impact during thermal runaway. The multi-layer thermal barrier design prevents any damage to the battery cells during compression during initial assembly and subsequent operation of the battery module.

[0008] Insulating layers between battery cells, such as lithium-ion battery (LIB) cells, can function as safety components that prevent or reduce excessive heat transfer between the cells. Preventing / reducing heat transfer between cells can perform the important safety function of reducing the likelihood of and / or delaying the onset of a "thermal runaway" event.

[0009] However, the requirements for an effective thermal barrier layer between cells go beyond simple thermal insulation properties. The environment within a battery pack may impose demands beyond the thermal regime and, in some embodiments, may include specific mechanical properties. In one exemplary embodiment, the thermal barrier may also preferably exhibit a degree of durability, so that the thermal barrier can form and act as a barrier or channel to prevent ejecta from a thermal runaway event from degrading other components of the battery pack (including other LIB cells). In other embodiments, an effective thermal barrier may also exhibit specific mechanical properties that reflect the dynamic conditions within the battery pack. This may include mechanical resilience and compressibility to accommodate the expansion and contraction of battery cells during charge and discharge. The mechanical resilience and compressibility enable the thermal barrier to consistently maintain contact with adjacent cells through the dimensional changes typically exhibited by cells during operation and charge cycles. Achieving these demanding performance goals is challenging for the many different types of insulating materials that may be used as thermal barriers.

[0010] In the embodiments described below, various multilayer thermal barriers are described that include an insulating layer stacked with one or more different layers. In various embodiments, the different layers may exhibit different properties, such that the multilayer thermal barrier as a composite element may meet multiple design criteria more effectively than a single layer (e.g., a single layer of insulating material). In some embodiments, an insulating layer may be stacked with (and / or attached to) an elastic layer, such that the multilayer stack may achieve both the mechanical and thermal requirements necessary for the thermal barrier to be effective. In some embodiments, one or more of the layers of the multilayer thermal barrier may have an extended region, such that the contour or outline ("footprint") of one or more layers of the multilayer thermal barrier extends beyond the footprint of the corresponding LIB cell.

[0011] Materials for the insulating layer The insulating materials described in the examples below can be used as a single heat-resistant layer or in combination with other layers that provide additional functionality to the multilayer construction, such as mechanical strength, compressibility, heat dissipation / conduction, etc. The insulating layers of the multilayer materials described herein are responsible for ensuring containment and control of heat flow from heat-generating components in small spaces, providing safety and fire prevention for such products in the fields of electronics, industrial, and automotive technology.

[0012] In many aspects of the present disclosure, the insulating layer functions as a flame / fire deflector layer, either by itself or in combination with other materials that enhance its ability to contain and control heat flow. For example, the insulating layer itself may be flame and / or hot gas resistant and may further include entrained particulate materials that modify or enhance heat containment and control.

[0013] One example of a highly effective insulating layer includes aerogel. Aerogel describes a class of materials based on their structure: low density, open-cell structure, large surface area (often 900 m / g or greater), and sub-nanometer pore size. The pores may be filled with a gas, such as air. Aerogels can be distinguished from other porous materials by their physical and structural properties. Aerogel material is an exemplary insulating material, but the invention is not limited thereto. Other thermal insulating materials, such as mica, microporous silica, ceramic fibers, mineral felt, and combinations thereof (both with and without aerogel material), may also be used in the examples of the present disclosure.

[0014] Selected examples of aerogel formation and properties are described below. In some examples, precursor materials are gelled to form a network of solvent-filled pores. The solvent is then extracted, leaving a porous matrix. A variety of different aerogel compositions are known, and they may be inorganic, organic, and inorganic / organic hybrids. Inorganic aerogels are generally based on metal alkoxides and include materials such as silica, zirconia, alumina, and other oxides. Organic aerogels include, but are not limited to, urethane aerogels, resorcinol formaldehyde aerogels, and polyimide aerogels.

[0015] Inorganic aerogels can generally be formed from metal oxide or metal alkoxide materials. The metal oxide or metal alkoxide materials can be based on the oxide or alkoxide of any metal capable of forming an oxide. Such metals include, but are not limited to, silicon, aluminum, titanium, zirconium, hafnium, yttrium, vanadium, cerium, and the like. Inorganic silica aerogels are traditionally made via the hydrolysis and condensation of silica-based alkoxides (e.g., tetraethoxysilane) or via the gelation of silicic acid or water glass. Other relevant inorganic precursor materials for silica-based aerogel synthesis include, but are not limited to, metal silicates such as sodium silicate or potassium silicate, alkoxysilanes, partially hydrolyzed alkoxysilanes, tetraethoxysilane (TEOS), partially hydrolyzed TEOS, condensation polymers of TEOS, tetramethoxysilane (TMOS), partially hydrolyzed TMOS, condensation polymers of TMOS, tetra-n-propoxysilane, partially hydrolyzed and / or condensation polymers of tetra-n-propoxysilane, polyethylsilicate, partially hydrolyzed polyethylsilicate, monomeric alkylalkoxysilanes, bis-trialkoxyalkyl or arylsilanes, polyhedral silsesquioxanes, or combinations thereof.

[0016] In certain embodiments of the present disclosure, pre-hydrolyzed TEOS, such as Silbond H-5 (SBH5, Silbond Corp), which is hydrolyzed to a water / silica ratio of about 1.9 to 2, may be used as commercially available or may be further hydrolyzed before incorporation into the gelation process. Partially hydrolyzed TEOS or TMOS, such as polyethyl silicate (Silbond 40) or polymethyl silicate, may also be used as commercially available or may be further hydrolyzed before incorporation into the gelation process.

[0017] Inorganic aerogels can also include gel precursors containing at least one hydrophobic group, such as alkyl metal alkoxides, cycloalkyl metal alkoxides, and aryl metal alkoxides, which can impart or improve certain properties to the gel, such as stability and hydrophobicity. Inorganic silica aerogels, specifically, can include hydrophobic precursors such as alkyl silanes or aryl silanes. The hydrophobic gel precursor may be used as the primary precursor material to form the framework of the gel material. However, hydrophobic gel precursors are more commonly used as co-precursors in combination with simple metal alkoxides to form amalgam aerogels. Hydrophobic inorganic precursor materials for silica-based aerogel synthesis include, but are not limited to, trimethylmethoxysilane (TMS), dimethyldimethoxysilane (DMS), methyltrimethoxysilane (MTMS), trimethylethoxysilane, dimethyldiethoxysilane (DMDS), methyltriethoxysilane (MTES), ethyltriethoxysilane (ETES), diethyldiethoxysilane, dimethyldiethoxysilane (DMDES), ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane (PhTES), hexamethyldisilazane, and hexaethyldisilazane. Any derivatives of any of the above precursors may also be used, particularly certain polymers of other chemical groups may be added to or crosslinked with one or more of the above precursors.

[0018] Organic aerogels are generally formed from carbon-based polymer precursors. Such polymeric materials include, but are not limited to, resorcinol formaldehyde (RF), polyimides, polyacrylates, polymethyl methacrylates, acrylate oligomers, polyoxyalkylenes, polyurethanes, polyphenols, polybutadiene, trialkoxysilyl-terminated polydimethylsiloxanes, polystyrenes, polyacrylonitriles, polyfurfural, melamine-formaldehyde, cresol formaldehyde, phenol-furfural, polyethers, polyols, polyisocyanates, polyhydroxybenzenes, polyvinyl alcohol dialdehyde, polycyanurates, polyacrylamides, various epoxies, agar, agarose, chitosan, and combinations thereof. As an example, organic RF aerogels are generally prepared from the sol-gel polymerization of resorcinol or melamine with formaldehyde under alkaline conditions.

[0019] Organic / inorganic hybrid aerogels are primarily composed of organically modified silica ("ormosil") aerogels. These ormosil materials contain organic components covalently bonded to the silica network. Ormosils are typically formed by the hydrolysis and condensation of an organically modified silane, R-Si(OX)3, with a conventional alkoxide precursor, Y(OX)4. In these formulas, X can represent, for example, CH3, CH5, CH7, or CH9; Y can represent, for example, Si, Ti, Zr, or Al; and R can be any organic fragment, such as methyl, ethyl, propyl, butyl, isopropyl, methacrylate, acrylate, vinyl, or epoxide. Additionally, the organic components in ormosil aerogels can be dispersed throughout the silica network or chemically bonded to it.

[0020] Aerogels can be formed from flexible gel precursors. Various flexible layers, including flexible fiber-reinforced aerogels, can be easily combined and shaped to obtain a preform that, when mechanically compressed along one or more axes, provides an object with high compressive strength along any of those axes.

[0021] One method of aerogel formation involves batch casting. Batch casting involves catalyzing an entire volume of sol to simultaneously induce gelation throughout that volume. Gel formation techniques involve adjusting the pH and / or temperature of a dilute metal oxide sol to a point where gelation occurs. Materials suitable for forming inorganic aerogels include oxides of most metals capable of forming oxides, such as silicon, aluminum, titanium, zirconium, hafnium, yttrium, and vanadium. Particularly preferred are gels formed primarily from alcoholic solutions of hydrolyzed silicate esters (alcogels) due to their ready availability and low cost. Organic aerogels can also be made from melamine formaldehyde, resorcinol formaldehyde, and the like.

[0022] As mentioned above, the aerogel may be organic, inorganic, or a mixture thereof. In some examples, the aerogel includes silica-based aerogel. One or more layers within the thermal barrier may include a reinforcing material. The reinforcing material may be any material that provides resilience, compliance, or structural stability to the aerogel material. Examples of reinforcing materials include, but are not limited to, open-cell macroporous framework reinforcement materials, closed-cell macroporous framework reinforcement materials, open-cell membranes, honeycomb reinforcement materials, polymeric reinforcement materials, and fibrous reinforcement materials such as, for example, staple fibers, woven materials, nonwoven materials, needled nonwovens, battings, webs, mats, and felts.

[0023] The reinforcing material can be selected from organic polymer-based fibers, inorganic fibers, carbon-based fibers, or combinations thereof. The inorganic fibers can be selected from glass fibers, rock fibers, metal fibers, boron fibers, ceramic fibers, basalt fibers, or combinations thereof. In some examples, the reinforcing material can include a reinforcement comprising multiple layers of material.

[0024] In addition to thermal insulating layers, thermally conductive layers in combination with thermal insulating layers are effective in directing unwanted heat to desired external locations, such as external heat dissipation fins, heat dissipation enclosures, or other external structures for dissipating unwanted heat to the ambient air. In one example, one or more thermally conductive layers help dissipate heat from localized heat loads within a battery module or pack. Examples of highly thermally conductive materials include carbon fiber, graphite, silicon carbide, metals including, but not limited to, copper, stainless steel, aluminum, and the like, as well as combinations thereof.

[0025] Insulation Layer Assembly In some embodiments, any of the multilayer thermal barriers described herein can be coupled to a heat sink as a way to further facilitate heat distribution and removal. It is understood that there are various heat sink types and configurations, as well as different techniques for coupling a heat sink to a thermally conductive layer, and the present disclosure is not limited to the use of any one type of heat sink / coupling technique. For example, at least one thermally conductive layer of the multilayer materials disclosed herein can be in thermal communication with an element of a battery module or pack's cooling system, such as a cold plate or cooling channel of the cooling system (i.e., "active cooling"). In another example, at least one thermally conductive layer of the multilayer materials described herein can be in thermal communication with other elements of a battery pack, battery module, or battery system that can function as a heat sink, such as a wall of the pack, module, or system, or with other elements of the multilayer material disposed between battery cells. Thermal communication between the thermally conductive layer of the multilayer material and a heat sink element in a battery system can allow excess heat to be removed from the cell(s) adjacent to the multilayer material to the heat sink, thereby reducing the impact, severity, or propagation of thermal events that may generate excess heat.

[0026] As described herein, a multilayer thermal barrier includes one or more insulating layers (such as aerogel, using the materials and methods described above) and at least one other layer. In some embodiments, in addition to the one or more thermal insulating layers, the multilayer thermal barrier assembly may include one or more of: (a) one or more thermally conductive layers and / or (b) one or more elastic material layers. In one example, the elastic layer, when included in the multilayer thermal barrier, may compress to accommodate expansion of one or more battery cells adjacent to the multilayer thermal barrier. In one scenario, the battery cells may expand during a charge cycle and contract during a discharge cycle. A multilayer thermal barrier including an elastic layer may compress in response to applied pressure from an adjacent expanding cell and expand in response to a decrease in pressure as the cell contracts. In one example, the elastic layer may also absorb permanent volumetric expansion caused by degradation and / or thermal runaway of any battery cell, rather than simply responding to cyclic, reversible expansion and contraction. The elastic material layer may include, but is not limited to, foam, fiber, fabric, sponge, spring structure, rubber, polymer, and combinations thereof.

[0027] As also described herein, the multilayer thermal barrier may also include one or more thermally conductive layers to facilitate heat transfer. The thermally conductive layers may also protect the insulating and elastic layers disposed between the thermally conductive layers from particle impact in the event of thermal runaway. In some embodiments, the thermally conductive layers each have a footprint (defined by width x length) equal to the footprint of the elastic layer and / or equal to the footprint of the battery cell 112 (defined by the width and length of the electrodes). In some embodiments, any of the multilayer thermal barriers described herein may be compatible with any configuration of battery cell, including, but not limited to, prismatic cells or pouch cells.

[0028] Pouch cell with thermal barrier 1A shows an example of a battery module 100 including a multi-layer thermal barrier of the present disclosure. The battery module 100 includes multiple cells 112, all of which are housed in a pouch 114. The battery module 100 also includes electrical contacts 116, a bus 118, electrical circuitry 119, and a thermal barrier 120.

[0029] The cells 112 of the battery module 100 may include lithium-ion cells, although the invention is not limited thereto. Other electrochemical cell and battery configurations that benefit from a thermal barrier are also within the scope of the invention.

[0030] In the illustrated embodiment, groups of cells 112 are grouped together in corresponding pouches 114. The pouches 114 are electrically connected to one another within the group 110 of pouches 114.

[0031] Within the pouch 114, the electrodes (not shown), separator (not shown), and electrolyte (not shown) of the battery cell 112 are disposed in a central portion of the pouch 114 defined by a footprint 126, with the edges of the pouch 114 filled with additional electrolyte. The major surfaces (width x length) of the battery cell 112 are defined as the footprint of the battery cell 112. For other battery cell shapes, the footprint may include other area shapes, such as an oval, a diamond, or other shapes. Terminals 116 are configured to contact the cell(s) 112 and extend from the pouch 114, as shown. Pouch cells or prismatic cells are frequently used in electric vehicle battery modules and can be used in the embodiments and examples discussed herein.

[0032] In addition to encasing the cells 112, each of the pouches 114 also includes electrical contacts 116 that connect to the cells 112. In the example of FIG. 1A, multiple terminals 116 from individual cells 112 of the group 110 are coupled together, either physically or electrically.

[0033] The terminals 116 may be connected to a bus 118 or other similar electrical structure. In one example, the bus 118 includes a slot that narrows from one side to another. When the terminals 116 slide into the bus 118, they compress, creating a robust electrical connection that does not require fasteners or tools for assembly. The bus 118 may be connected to an electrical circuit 119.

[0034] The battery module 100 further includes a thermal barrier 120 positioned between the cells 110. In some embodiments, the thermal barrier 120 may include a single layer. For example, the thermal barrier 120 may include a thermal insulation layer 122 made from an insulating material (e.g., aerogel, ceramic fiber). In some examples, the single barrier layer may be coated with a protective barrier, such as a polymer encapsulant or an inorganic or organic material coating. In some examples, the protective barrier may be applied using a dip coating process, doctor blade, vapor coating, spin coating, spraying, chemical vapor deposition, or the like. In other examples, the polymer encapsulant may be physically applied in the form of a polymer film.

[0035] In other embodiments, the thermal barrier 120 can be a multi-layer thermal barrier 120 including a thermal insulating layer 122 and at least one elastic layer 124. In the example of Figure 1A, two elastic layers 124 are shown positioned on opposite major surfaces of the thermal insulating layer 122, such that the thermal insulating layer 122 is between the opposite major surfaces of the two elastic layers 124, although the invention is not so limited.

[0036] As described in more detail below, the dimensions (i.e., width and length) of the major surfaces of the elastic layer(s) 124 can be approximately the same (e.g., 5% or less) as the dimensions (i.e., width and length) of the major surfaces of the thermal insulation layer 122. In other embodiments, the height and length dimensions of the major surfaces of the elastic layer(s) 124 and the insulation layer 122 can be different. For convenience, the width and length of the major surfaces are referred to as "footprints." In some embodiments, the footprint of the elastic layer is the same as the footprint of the battery cell 112 (defined by the width x length of the electrodes).

[0037] As shown in the exemplary battery module 100, the thermal insulation layer 122 extends laterally beyond the footprint 126 of the resilient layer 124 by a distance indicated by dimension 128. Dimension 128 may be configured and dimensioned to fit within a battery compartment, a battery pack frame, or other similar externally imposed design constraints. The battery cells 112 within the battery module 100 are compressed against each other during assembly to maintain pressure within each battery cell 112. The pressure on each of the battery cells 112 maintains electrical contact between the active components of the battery cells 112 disposed within the pouch 114. For example, the stack of cells 112 is compressed as indicated by arrow 102 in FIG. 1A .

[0038] The compression operation also compresses the multi-layer thermal barrier 120. In configurations where multiple layers of the multi-layer thermal barrier 120 extend laterally beyond the footprint 126, the laterally extending portions may not compress but instead curl upward and downward or have bulging edges. This can cause undesirable interference with the pouch 114 and terminals 116. Excessive curling or expansion can damage the terminals 116.

[0039] 1A , only the thermal insulation layer 122 extends laterally beyond the footprint 126. This provides a thermal barrier that is wider than the footprint 126, improving thermal protection between the cells 112 or subunits 110. However, undesirable curling of other layers of the multilayer thermal barrier 120 is avoided by configuring other layers, such as the elastic layer 124, to be sized with a footprint that is substantially the same size as the footprint 126. In one example, the thermal insulation layer 122 extends beyond the footprint 126 to block the transfer of heat and venting material between the battery subunits 110.

[0040] In one embodiment, one or more thermal conductor layers are also included as part of the multilayer thermal barrier 120. The one or more thermal conductor layers help remove excess heat from the cell(s) 112 adjacent to the multilayer material to a heat sink. FIG. 1B shows a cross-sectional view of the battery module 100 along line AA, including a heat sink 130. A subunit 110 is shown with a thermal insulation layer 122 extending laterally beyond the footprint 126. The inclusion of one or more thermal conductor layers in the multilayer thermal barrier 120 facilitates lateral thermal conduction within the one or more thermal conductor layers and to the heat sink 130 through thermal contact at the interface 132. In one example, an additional thermal conductor, e.g., a metal layer, is coupled between the thermally conductive layer in the multilayer thermal barrier 120 and the heat sink 130 to provide a continuous lateral thermal path from the center of the cell 112 to the heat sink 130.

[0041] In some embodiments, the lateral extension of the thermal insulation layer 122 provides additional thermal protection between the cells 112 or groups 110 of cells 112. In one example, the thermal insulation layer (122) extends beyond the footprint 126 to block heat and ejecta generated by a thermal runaway event from transferring between battery subunits 110.

[0042] Thermal Barrier Configuration Thermal barriers, particularly multilayer thermal barriers, are composite structures that can be designed to have multiple properties that cannot be easily achieved with a single layer alone due to the different properties of the various layers. For example, as described above, thermal barriers generally include a thermal insulating layer, but various other configurations may include one or more different layers to achieve purposes not strictly related to thermal insulation. In various embodiments, the one or more different layers may include, but are not limited to, an elastic layer, a thermally conductive layer, a dust barrier, etc. The dimensions of the various layers are designed to fulfill their respective purposes. For example, the insulating layer may extend beyond the footprint of the battery cells to better block heat during thermal runaway. The insulating layer may have thin edges to prevent accidental damage to the battery cell pouch or terminals. The elastic and conductive layers typically fit the same footprint as the battery cells, providing appropriate pressure between the battery cells and dissipating the heat generated by the battery cells.

[0043] 2A-2D show selected configurations of multi-layer thermal barriers. The compositions of the various layers are described above. Those descriptions are equally applicable to similar layers in the configurations described below.

[0044] Referring initially to FIG. 2A, the multi-layer thermal barrier 200 includes a thermal insulating layer 202, a first elastic layer 204A, a second elastic layer 204B (collectively, elastic layers 204), a first thermally conductive layer 206A, and a second thermally conductive layer 206B (collectively, thermally conductive layers 206).

[0045] As shown, the thermal insulation layer 202, fabricated from any of the materials described above, may have one or more dimensions that extend beyond the corresponding dimensions of one or more of the other layers. In the case of the multi-layer thermal barrier 200, the thermal insulation layer 202, in the illustrated dimensions, extends beyond all of the elastic layer 204 and the thermal conductor layer 206 by dimension 209. In other embodiments not shown, one or more of the elastic layer 204 and / or the thermally conductive layer 206 may have one or more dimensions that are comparable to the corresponding dimensions of the thermal insulation layer 202.

[0046] In some embodiments of the multi-layer thermal barrier 200, the thermally conductive layers 206A and 206B are adjacent to opposite major surfaces of the thermal insulation layer 202. In some embodiments, the thermally conductive layers 206A and 206B are in direct contact with the corresponding major surfaces of the thermal insulation layer 202. In other embodiments, the thermally conductive layers 206A and 206B are in indirect contact with the corresponding major surfaces of the thermal insulation layer 202. In indirect contact embodiments, an adhesive or thermally conductive adhesive / interface material (e.g., graphite paste, conductive particle-filled adhesive) may be disposed between the thermally conductive layers 206A and 206B and the thermal insulation layer 202.

[0047] The elastic layers 204 of the multi-layer thermal barrier 200 are in contact with the thermally conductive layers 206, such that both the thermally insulating layer 202 and the thermally conductive layer 206 are between the elastic layers 204A and 204B. In some embodiments, the elastic layers 204 are in direct contact with the corresponding thermally conductive layers 206. In other embodiments, an adhesive or other layer may be present between one of the elastic layers 204 and the corresponding thermally conductive layer 206.

[0048] 2B is a multi-layer thermal barrier 210 having an alternative configuration to the multi-layer thermal barrier 200 of FIG. 2A. The multi-layer thermal barrier 210 includes a thermally insulating layer 212, a first elastic layer 214A, a second elastic layer 214B, a first thermally conductive layer 216A, and a second thermally conductive layer 216B.

[0049] The materials of the various layers of the multi-layer thermal barrier 210 are the same as those described above. In some embodiments, the thermally insulating layer extends a distance 229 beyond one or more dimensions of the elastic layer 214 and / or the thermally conductive layer 216.

[0050] The layer configuration of the multi-layer thermal barrier 210 includes a first resilient layer 214A and a second resilient layer 214B in contact with opposite major surfaces of the thermal insulation layer 212. In some embodiments, the first resilient layer 214A and the second resilient layer 214B are in direct contact with the corresponding major surfaces of the thermal insulation layer 212. In other embodiments, the first resilient layer 214A and the second resilient layer 214B are in indirect contact with the thermal insulation layer 212 using an adhesive, an encapsulation or coating of the thermal insulation layer, or some other material interposed therebetween.

[0051] The multi-layer thermal barrier 220 is shown in Figure 2C. The multi-layer thermal barrier 220 includes a thermally insulating layer 222, a first resilient layer 224A, a second resilient layer 224B, and a thermally conductive layer 226. The compositions and materials of these layers are described above.

[0052] The thermally conductive layer 226 of the multi-layer thermal barrier 220 is configured to encapsulate the thermally insulating layer 222. The thermally conductive layer 226 provides increased conduction capacity. The encapsulating layer 226 also protects the insulating layer 222 from particle bombardment during a thermal runaway event. In embodiments where the thermally insulating layer 222 is fabricated from an aerogel material, the encapsulating thermally conductive layer 226 prevents aerogel dust from escaping from the insulating layer 222.

[0053] In some embodiments, thermally conductive layer 226 is formed from a single, unitary element, such as a compatible polymer layer containing thermally conductive filler particles. In other embodiments, the single, unitary element can be a graphite layer. In other embodiments, thermally conductive layer 226 can be a metal layer, a metal alloy layer, a carbon layer, another thermally conductive layer, or a combination thereof. In other embodiments, thermally conductive layer 226 is formed from one or more separate elements bonded together (e.g., bonded panels similar to the first and second thermally conductive layers described above).

[0054] The multi-layer thermal barrier 220 also includes a first elastic layer 224A and a second elastic layer 224B disposed on the exposed surface(s) of the thermally conductive layer 226, such that the thermally conductive layer 226 is between the thermally insulating layer 222 and the first elastic layer 224A and the second elastic layer 224B.

[0055] Dimension 228 indicates the width of first resilient layer 224 A and second resilient layer 224 B. As shown, portion 223 of thermal insulation layer 222 extends laterally beyond dimension 228 by dimension 229.

[0056] The multi-layer thermal barrier 230 shown in FIG. 2D includes a thermal insulating layer 232, a first elastic layer 234A, a second elastic layer 234B (collectively, elastic layers 234), a first thermally conductive layer 236A, and a second thermally conductive layer 236B (collectively, thermally conductive layers 236).

[0057] In multi-layer thermal barrier 230, first resilient layer 234A is located between thermally insulating layer 232 and first thermally conductive layer 236A. Second resilient layer 234B is located between thermally insulating layer 232 and second thermally conductive layer 236B. Resilient layer 234 and thermally conductive layer 236 have a width indicated by dimension 238. Portion 233 of thermally insulating layer 232 extends laterally beyond dimension 238 by dimension 239.

[0058] Portion 233 of thermal insulation layer 232 of multilayer thermal barrier 230 is further modified from a first thickness 242 to a second thickness 244 that is less than first thickness 242. In one example, material is removed from thermal insulation layer 232 to reduce the thickness of portion 233. Exemplary techniques for reducing the thickness of thermal insulation layer 232 from thickness 242 to thickness 244 include, but are not limited to, cutting with a blade (e.g., skiving) or initially forming portion 233 different from an intermediate portion of thermal insulation layer 232 (e.g., via a mold or die). In one example, portion 233 is compressed or otherwise formed from first thickness 242 to second thickness 244. Exemplary methods of reduction include, but are not limited to, rolling, stamping, or other similar techniques.

[0059] 2E shows a cross-sectional view of a portion of a battery module including a thermal insulating layer 240, similar to the cross-section along line AA in FIG. 1A or line DD in FIG. 2C. The thermal barrier 240 can include any of the embodiments described above in the context of FIGS. 1 and 2A-2D.

[0060] Both the conductive layer 246 and the aforementioned thermal insulating layer of the thermal barrier 240 have footprints that are larger than the footprint of the elastic layer 243. The footprint of the elastic layer 243 is defined by a length 248 by a width 247. The footprint of the elastic layer 243 may be the same as the footprint of a battery cell (not shown). The conductive layer 246 is in direct contact with the cold plate 245, although the elastic layer 243 may optionally not be in direct contact with the cold plate 245. For example, the elastic layer 243 may be separated from the cold plate 245 by a space 241, which is filled with the conductive layer 246.

[0061] 2F shows a cross-sectional view of a battery module 250 similar to module 100 taken along line BB in FIG. 1A or line CC in FIG. 2C. The battery module includes a thermal barrier 251. Battery module 250 may include any of the embodiments described above in the context of FIGS. 1 and 2A-2D.

[0062] The battery module 250 includes a group of battery cells 110. Each group 110 includes one or more battery cells 112. The battery module 250 further includes a multi-layer thermal barrier 251 including a conductive layer 256 and an elastic layer 254. The multi-layer thermal barrier 251 may further include a thermal insulating layer encapsulated in the conductive layer 256. The multi-layer thermal barrier 251 has a thickness 252.

[0063] Although the conductive layer 256 of the multilayer thermal barrier 251 in the battery module 250 is shown in direct contact with the cold plate 245, the present disclosure is not limited thereto. In one embodiment, the elastic layer 254 is not in direct contact with the cold plate 245. For example, the elastic layer can be separated from the cold plate 245 by a distance 253, with the distance 253 being filled with the conductive layer 256. As such, the conductive layer has a T-shaped cross section along its thickness. The T-shaped cross section increases the contact area between the conductive layer 256 and the cold plate 245, increasing the rate of heat dissipation.

[0064] 3A-3C illustrate the compression of a multi-layer thermal barrier 300 according to one example. In FIG. 3A, the multi-layer thermal barrier 300 includes a thermal insulation layer 302. The multi-layer thermal barrier 300 also includes top and bottom resilient layers 304 and top and bottom thermal conductor layers 306. In the example of FIG. 3A, the top and bottom resilient layers 304 are positioned between the thermal insulation layer 302 and the top and bottom thermal conductor layers 306. The thermal insulation layer 302 is shown having an initial thickness 312, and the entire multi-layer thermal barrier 300 is shown having a thickness 310.

[0065] In Figure 3B, the multilayer thermal barrier 300 is compressed, as indicated by arrow 308. In Figure 3B, the thickness 310 decreases to a thickness approaching thickness 312 as the elastic layer 304 is compressed. In Figure 3C, the thickness 310 is further decreased to a thickness substantially equal to thickness 312.

[0066] While the exemplary multi-layer thermal barrier and associated battery module described above shows multiple elastic layers and multiple thermal conductor layers with a single thermal insulation layer, the invention is not so limited. Other examples include multi-layer thermal barriers with fewer or more layers depending on elasticity, thermal barrier, and thermal conduction requirements.

[0067] FIG. 4 shows a flow diagram of an example manufacturing method. In operation 402, several lithium-ion pouch cells are stacked. In operation 404, a multi-layer thermal barrier is stacked between the cells in the stack of lithium-ion pouch cells. In one example, the multi-layer thermal barrier includes an aerogel thermal insulation layer, a thermally conductive layer, and an elastic layer stacked together with the aerogel thermal insulation layer and the thermally conductive layer, the elastic layer being sized to a footprint substantially the same size as the lithium-ion pouch cells, and the aerogel thermal insulation layer extending laterally beyond the footprint. In operation 406, the battery module is compressed, causing the elastic layer of the multi-layer thermal barrier to compress to a portion of its original thickness.

[0068] Battery modules including the above-described multi-layer thermal barriers have been used in several electronic devices. Figure 5 shows an exemplary electronic device 500 including a battery module 510. The battery module 510 is coupled to functional electronics 520 by circuitry 512. In the illustrated example, the battery module 510 and circuitry 512 are housed in a housing 502. A charging port 514 is shown coupled to the battery module 510 to facilitate recharging the battery module 510 when needed.

[0069] In one example, functional electronics 520 includes devices such as semiconductor devices with transistors and memory circuits, including, but not limited to, telephones, computers, display screens, navigation systems, etc.

[0070] FIG. 6 illustrates another electronic system utilizing a battery module including a multi-layer thermal barrier as described above. An electric vehicle 600 is illustrated in FIG. 6. The electric vehicle 600 includes a chassis 602 and wheels 622. In the illustrated example, each wheel 622 is coupled to a drive motor 620. A battery module 610 is shown coupled to the drive motor 620 by circuitry 606. A charge port 604 is shown coupled to the battery module 610 to facilitate recharging the battery module 610 when needed.

[0071] Examples of electric vehicles 600 include, but are not limited to, consumer vehicles such as cars and trucks. Commercial vehicles such as tractors and semi-trucks are also within the scope of the present invention. Although a four-wheeled vehicle is shown, the present invention is not so limited. Two-wheeled vehicles, such as motorcycles and scooters, are also within the scope of the present invention.

[0072] In order to more fully describe the methods and apparatus disclosed herein, a non-limiting list of aspects is provided herein.

[0073] Aspect 1. A multi-layer thermal barrier comprising: a thermal insulating layer; a thermally conductive layer; and an elastic layer stacked together with said thermal insulating layer and said thermally conductive layer, said elastic layer being sized to a footprint substantially the same size as a lithium ion pouch cell, and said thermal insulating layer extending laterally beyond said footprint.

[0074] Embodiment 2. The multilayer thermal barrier of embodiment 1, wherein the thermal insulation layer comprises an aerogel material.

[0075] Aspect 3. The multi-layer thermal barrier of aspect 1, wherein the thermally conductive layer is sized to a footprint of substantially the same size as the elastic layer.

[0076] Aspect 4. The multilayer thermal barrier of Aspect 1, wherein the thermal insulation layer is between the elastic layer and the thermal insulation layer.

[0077] Aspect 5. The multilayer thermal barrier of Aspect 1, wherein the thermally conductive layer includes a first thermally conductive layer and a second thermally conductive layer, and the thermally insulating layer is between and in direct contact with the first thermally conductive layer and the second thermally conductive layer.

[0078] Aspect 6. The multilayer thermal barrier of Aspect 5, wherein the elastic layer comprises a first elastic layer and a second elastic layer, the first elastic layer being in direct contact with the first thermally conductive layer, and the second elastic layer being in direct contact with the second thermally conductive layer.

[0079] Aspect 7. The multilayer thermal barrier of Aspect 6, wherein the elastic layer comprises a first elastic layer and a second elastic layer, and the thermal insulation layer is between and in direct contact with the first elastic layer and the second elastic layer.

[0080] Aspect 8. The multilayer thermal barrier of Aspect 7, wherein the thermally conductive layer comprises a first thermally conductive layer and a second thermally conductive layer, the first thermally conductive layer being in direct contact with the first elastic layer, and the second thermally conductive layer being in direct contact with the second elastic layer.

[0081] Aspect 9. The multilayer thermal barrier of Aspect 1, wherein the thermal insulation layer includes a first portion overlapping a corresponding portion of one or both of the thermally conductive layer and the elastic layer, the first portion having a first thickness, and a second portion extending beyond the footprint, the second portion having a second thickness smaller than that of the first portion.

[0082] Aspect 10. A battery module comprising: a stack of lithium ion pouch cells; and a multi-layer thermal barrier positioned between cells in the stack of lithium ion pouch cells, the multi-layer thermal barrier including a thermal insulating layer, a thermally conductive layer, and an elastic layer stacked together with the thermal insulating layer and the thermally conductive layer, the elastic layer being sized to a footprint substantially the same size as a lithium ion pouch cell, and the thermal insulating layer extending laterally beyond the footprint.

[0083] Aspect 11. The battery module of aspect 10, wherein the thermal insulation layer comprises an aerogel material.

[0084] Aspect 12. The battery module of aspect 10, wherein one or more pouch cells in the stack of lithium ion pouch cells include opposing terminal electrodes extending from the pouch.

[0085] Embodiment 13. The battery module of embodiment 10, wherein the multi-layer thermal barrier is located between two multi-pouch cell subunits.

[0086] Aspect 14. The battery module of aspect 10, further comprising a heat sink in contact with a side of the stack of lithium ion pouch cells and thermally coupled to the thermally conductive layer.

[0087] Aspect 15. The battery module of aspect 10, wherein the thermally conductive layer encapsulates the thermally insulating layer.

[0088] Aspect 16. A method of making a battery module, the method comprising: stacking several battery cells to form a stack of battery cells; stacking a multi-layer thermal barrier between cells in the stack of battery cells, the multi-layer thermal barrier comprising an aerogel thermal insulation layer, a thermal conduction layer, and an elastic layer stacked together with the aerogel thermal insulation layer and the thermal conduction layer, the elastic layer being sized to a footprint substantially the same size as a battery cell, and the aerogel thermal insulation layer extending laterally beyond the footprint; and compressing the battery module, wherein the elastic layer of the multi-layer thermal barrier compresses to a portion of its original thickness.

[0089] Aspect 17. The method of aspect 16, further comprising reducing the thickness of a portion of the aerogel thermal insulation layer that extends laterally beyond the footprint.

[0090] Aspect 18. The method of aspect 17, wherein reducing the thickness comprises compressing the portion.

[0091] Aspect 19. The method of aspect 17, wherein reducing the thickness comprises removing material from the portion of the aerogel thermal insulation layer.

[0092] Aspect 20. The method of aspect 16, wherein compressing the battery module comprises compressing the multilayer thermal barrier until a thickness of a central portion of the multilayer thermal barrier is substantially equal to a thickness of a portion of the aerogel thermal insulation layer that extends laterally beyond the footprint.

[0093] The above description is intended to be illustrative, not limiting. For example, the above-described aspects (or one or more aspects thereof) may be used in combination with each other. Other aspects may be employed, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to enable the reader to quickly grasp 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, various features may be grouped together to streamline the disclosure. This should not be construed as intending that any unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter lies in less than all features of a particular disclosed embodiment. Accordingly, the following claims are incorporated into the Detailed Description herein, 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 variations. The scope of the invention should be determined with reference to the appended claims, along with the full range of equivalents to which such claims are entitled.

[0094] Although the inventive subject matter has been generally described with reference to certain exemplary embodiments, various modifications and changes can be made to these embodiments without departing from the broader scope of the disclosed embodiments. Such embodiments of the inventive subject matter may be referred to herein, individually or collectively, by the term "invention" for convenience only, and this is not intended to intentionally limit the scope of this application to any single disclosure or inventive concept where multiple inventions are in fact disclosed.

[0095] The embodiments illustrated herein are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of the present disclosure. Therefore, the detailed description is not to be construed in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0096] As used herein, the term "or" may be interpreted in either an inclusive or exclusive sense. Furthermore, multiple instances may be provided for resources, operations, or structures described herein as a single instance. Moreover, boundaries between various resources, operations, modules, engines, and data stores are somewhat arbitrary, and particular operations are illustrated in the context of specific exemplary configurations. Other allocations of functionality are contemplated and may be included within the scope of various aspects of the disclosure. In general, structures and functionality that are represented as separate resources in an exemplary configuration may be implemented as a combined structure or resource. Similarly, structures and functionality that are represented as a single resource may be implemented as separate resources. These and other variations, modifications, additions, and improvements are within the scope of the aspects of the disclosure as expressed by the appended claims. Accordingly, the specification and drawings should be regarded in an illustrative and not a restrictive sense.

[0097] The foregoing description, for purposes of illustration, has been set forth with reference to specific exemplary embodiments. However, the foregoing exemplary description is not intended to be exhaustive or to limit possible exemplary embodiments to the precise forms disclosed. Many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to best explain the principles involved and their practical application, thereby enabling those skilled in the art to best utilize various exemplary embodiments, with their various modifications, as suited to the particular uses intended.

[0098] It is also understood that terms such as "first" and "second" may be used herein to describe various elements, but these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first contact can be referred to as a second contact, and similarly, a second contact can be referred to as a first contact, without departing from the scope of the present exemplary embodiment. Although the first contact and the second contact are both contacts, they are not the same contact.

[0099] The terminology used in the description of exemplary embodiments herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. As used in the description of the exemplary embodiments and the accompanying examples, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "and / or," as used herein, is also understood to refer to and encompass any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms "comprise" and / or "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0100] As used herein, the term "if" may be interpreted 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 interpreted to mean "upon determining" or "in response to determining" or "upon detecting [the stated condition or event]" or "in response to detecting [the stated condition or event]," depending on the context.

Claims

1. A multi-layer thermal barrier comprising: a thermal insulating layer; a thermally conductive layer; a resilient layer stacked together with the thermally insulating layer and the thermally conductive layer, the resilient layer being sized to a footprint substantially the same size as a lithium-ion pouch cell; The multi-layer thermal barrier, wherein the thermal insulating layer extends laterally beyond the footprint.

2. The multi-layer thermal barrier of claim 1 , wherein the thermal insulation layer comprises an aerogel material.

3. The multi-layer thermal barrier of claim 1 , wherein the thermally conductive layer is sized to a footprint substantially the same size as the resilient layer.

4. The multi-layer thermal barrier of claim 1 , wherein the thermal insulating layer is between the resilient layer and the thermal insulating layer.

5. the thermally conductive layer includes a first thermally conductive layer and a second thermally conductive layer; The multi-layer thermal barrier of claim 1 , wherein the thermally insulating layer is between and in direct contact with the first and second thermally conductive layers.

6. the elastic layer includes a first elastic layer and a second elastic layer; The multi-layer thermal barrier of claim 5 , wherein the first elastic layer is in direct contact with the first thermally conductive layer and the second elastic layer is in direct contact with the second thermally conductive layer.

7. the elastic layer includes a first elastic layer and a second elastic layer; The multi-layer thermal barrier of claim 6 , wherein the thermal insulating layer is between and in direct contact with the first and second resilient layers.

8. the thermally conductive layer includes a first thermally conductive layer and a second thermally conductive layer; The multi-layer thermal barrier of claim 7 , wherein the first thermally conductive layer is in direct contact with the first elastic layer and the second thermally conductive layer is in direct contact with the second elastic layer.

9. The thermal insulation layer is a first portion overlapping a corresponding portion of one or both of the thermally conductive layer and the elastic layer, the first portion having a first thickness; a second portion extending beyond the footprint, the second portion having a second thickness less than the first portion.

10. A battery module, A stack of lithium-ion pouch cells, a multi-layer thermal barrier positioned between cells in the stack of lithium-ion pouch cells, a thermal insulating layer; a thermally conductive layer; a resilient layer stacked together with the thermally insulating layer and the thermally conductive layer, the resilient layer being sized to a footprint substantially the same size as a lithium-ion pouch cell; the multi-layer thermal barrier, wherein the thermal insulation layer extends laterally beyond the footprint.

11. The battery module of claim 10 , wherein the thermal insulation layer comprises an aerogel material.

12. 11. The battery module of claim 10, wherein one or more pouch cells in the stack of lithium ion pouch cells include opposing terminal electrodes extending from the pouch.

13. 11. The battery module of claim 10, wherein the multi-layer thermal barrier is located between two multi-pouch cell subunits.

14. 11. The battery module of claim 10, further comprising a heat sink in contact with a side of the stack of lithium-ion pouch cells and thermally coupled to the thermally conductive layer.

15. The battery module of claim 10 , wherein the thermally conductive layer encapsulates the thermally insulating layer.

16. 1. A method of fabricating a battery module, comprising: stacking several battery cells to form a stack of battery cells; stacking a multi-layer thermal barrier between cells in the stack of battery cells, the multi-layer thermal barrier comprising: an aerogel thermal insulation layer; a thermally conductive layer; a resilient layer stacked together with the aerogel thermal insulation layer and the thermal conduction layer, the resilient layer being sized to a footprint substantially the same size as a battery cell; the stacking, wherein the aerogel thermal insulation layer extends laterally beyond the footprint; compressing the battery module, wherein the resilient layer of the multi-layer thermal barrier compresses to a portion of its original thickness.

17. 17. The method of claim 16, further comprising reducing a thickness of a portion of the aerogel thermal insulation layer that extends laterally beyond the footprint.

18. The method of claim 17 , wherein reducing the thickness comprises compressing the portion.

19. 20. The method of claim 17, wherein reducing the thickness comprises removing material from the portion of the aerogel thermal insulation layer.

20. 17. The method of claim 16, wherein compressing the battery module comprises compressing the multilayer thermal barrier until a thickness of a central portion of the multilayer thermal barrier is substantially equal to a thickness of a portion of the aerogel thermal insulation layer that extends laterally beyond the footprint.

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