Double-walled battery enclosure to provide heat transfer

Abstract

A double-walled enclosure for thermal management of a battery pack includes an inner hollow structure having an inner surface and an outer surface, wherein one or more battery modules are disposed in the inner hollow structure, and an outer hollow structure having an inner surface, wherein the outer surface of the inner hollow structure is in contact with the inner surface of the outer hollow structure, or the outer surface of the inner hollow structure forms at least one channel with the inner surface of the outer hollow structure through which a heat transfer fluid flows, and wherein the inner hollow structure is formed from a polymer material such that the inner hollow structure is in thermal contact with the heat transfer fluid to provide thermal management for the battery pack.

Description

[Technical Field]

[0001] The present invention relates to a battery enclosure used to provide thermal management of a battery, or a battery module and / or battery pack. [Background technology]

[0002] The statements in this section provide background information related to the present disclosure and definitions of some of the terms used in the disclosure, and do not necessarily constitute prior art.

[0003] Currently, electric vehicles (EVs) and hybrid electric vehicles (HEVs) commonly use aluminum plates to transfer heat between the battery pack and the battery. These plates are typically located at the bottom of the battery pack, which typically contains multiple batteries or battery modules. The plates allow fluid to circulate through them for heat transfer purposes. Common fluid types include water or a water / glycol mixture. Because aluminum plates are electrically conductive, a polymer foam pad or adhesive layer is typically placed between the battery and the cooling plate within the battery pack. This pad is in physical contact with both the battery and the cooling plate. The use of this pad also eliminates air gaps caused by assembly tolerances and roughness of the outer surfaces of the battery and the cooling plate. The combination of this pad or adhesive layer with the aluminum plate can adversely affect the cost, assembly, recycling, and weight of the battery pack / cooling plate combination.

[0004] Another type of cooling plate can be formed by using a film or composite foil as a flexible top layer and connecting it to a rigid bottom plate. This film or composite foil has a very thin cross-section, on the order of 100 micrometers (μm) or less. The composite foil is inflated like a balloon by the fluid circulating inside. All contact force to the battery is achieved through this inflation technique. However, the performance and durability of this type of cooling plate have yet to be established, as the thin cross-section of the inflatable film has limited thermal conductivity and is susceptible to tearing. Additionally, the thin film or composite foil may not be able to withstand the weight or dynamic forces exerted by the battery it is intended to support.

[0005] Finally, a third method of battery heat removal has limited use in some automotive hybrid vehicles, such as the McLaren Speedtail. This method involves surrounding the battery with a dielectric fluid. This type of thermal management process requires the dielectric fluid to be circulated or forced to flow through an external heat exchanger, which removes the heat generated by the battery. Furthermore, the use of dielectric fluid in this method relies on the availability of such large quantities and the associated costs. Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present disclosure to overcome the aforementioned drawbacks and to provide an improved battery enclosure for use in thermal management of a battery or battery pack. [Means for solving the problem]

[0007] In this regard, the present disclosure generally includes a double-walled enclosure for thermal management of a battery. The double-walled enclosure includes an inner hollow structure having an inner surface and an outer surface, the inner hollow structure having one or more battery modules disposed therein, and an outer hollow structure having an inner surface, the outer surface of the inner hollow structure being in contact with the inner surface of the outer hollow structure, or the outer surface of the inner hollow structure forming at least one channel with the inner surface of the outer hollow structure through which a heat transfer fluid flows. The inner hollow structure includes a polymer material such that the inner hollow structure is in thermal contact with the heat transfer fluid, thereby providing thermal management for the battery pack. The polymer material may include a thermally conductive polymer material.

[0008] The inner hollow structure of the double-walled enclosure has a wall thickness ranging from about 0.3 millimeters (mm) to about 2.5 mm. Similarly, the outer hollow structure has a wall thickness ranging from about 1 mm to about 5 mm.

[0009] A cavity may be formed between one or more battery modules and an interior surface of the inner hollow structure, and the cavity is at least partially filled with a heat transfer medium, which may include, but is not limited to, a single-phase dielectric fluid, a multi-phase dielectric fluid, a phase change material, or a combination thereof.

[0010] The at least one channel formed between the inner hollow structures and the outer hollow structures may be located above, below, at least one side of, or a combination thereof with respect to one or more battery modules. The heat transfer fluid flowing through the at least one channel may be, but is not limited to, water, glycol, or a water / glycol mixture. The heat transfer fluid may be circulated through a radiator, chiller, heat exchanger, or the like.

[0011] The polymeric material forming the inner hollow structure may include an elastomer, a thermoplastic, a thermoplastic elastomer (TPE), or a combination thereof. If desired, the polymeric material may have a Shore A hardness ranging from about 40 to 100, or a Shore D hardness ranging from 20 to about 75. Generally, if improved thermal conductivity is desired, the polymeric material may be a thermally conductive polymeric material. Generally, thermally conductive polymeric materials may include polymers having inherent thermal conductivity, blends of polymers where one or more polymers in the blend have inherent thermal conductivity, composite polymeric materials including at least one polymer configured as a polymer matrix and a thermally conductive filler dispersed in the polymer matrix, or combinations thereof.

[0012] When the thermally conductive polymer material composition includes a composite polymer material having a polymer matrix with a thermally conductive filler dispersed therein, the thermally conductive filler may include a plurality of particles having a composition selected from the group consisting of boron nitride, alumina, aluminum nitride, silicon nitride, silicon carbide, graphene, carbon nanotubes, or mixtures thereof. The polymer matrix may include an elastomer, thermoplastic resin, or thermoplastic elastomer (TPE) having a Shore A hardness ranging from about 40 to 100 or a Shore D hardness ranging from 20 to about 75. Alternatively, the composite polymer material composition may include a plurality of boron nitride particles dispersed in a thermoplastic elastomer (TPE) having a Shore A hardness ranging from about 70 to about 80. The content of the thermally conductive filler may range from about 5 wt% to about 25 wt% based on the total weight of the composite polymer material.

[0013] The composition of the outer hollow structure may include any standard or known polymer composition capable of providing structural support to the battery pack, including, but not limited to, high density polyethylene (HDPE), polypropylene (PP), or polyamide (PA), or combinations thereof, either as copolymers, polymer blends / mixtures, multilayer structures, or composites.

[0014] According to one aspect of the present disclosure, the inner hollow structure may include one or more structural elements configured to support the weight of the battery or function as bump stops configured to assist in battery placement and retention. These structural elements may be of the same or different composition as the inner hollow structure. Furthermore, these structural elements may be integrally formed with the inner hollow structure or formed as insert members connected to the inner hollow structure.

[0015] According to another aspect of the present disclosure, at least one of the exterior surface of the inner hollow structure or the interior surface of the outer hollow structure may optionally include one or more features configured to increase rigidity and to facilitate fluid mixing by directing fluid flow. These features may protrude into at least one channel, provided that at least a portion of the exterior surface of the inner hollow structure forming part of said at least one channel is flat so as to maintain at least 50% surface contact with the heat transfer fluid in said at least one channel. The inner hollow structure and the outer hollow structure undergo a volumetric change of less than about 15% upon allowing the heat transfer fluid to flow through the at least one channel.

[0016] According to another aspect of the present disclosure, there is provided a battery pack with thermal management, the battery pack including at least one battery module and a double-walled enclosure having an inner hollow structure and an outer hollow structure, as described above and further defined herein.

[0017] According to another aspect of the present disclosure, the double-walled enclosure may be used to provide thermal management of at least one battery in an electric vehicle (EV) or hybrid electric vehicle (HEV).

[0018] According to yet another aspect of the present disclosure, there is provided a process for forming a battery pack configured for thermal management. The process includes providing a polymer material, molding an inner hollow structure from the polymer material, the inner hollow structure having an outer surface surrounding the outer surface of the inner hollow structure, the outer surface of the inner hollow structure being in contact with the inner surface of the outer hollow structure or forming at least one channel with the inner surface of the outer hollow structure; providing at least one battery; assembling the at least one battery within the inner hollow structure such that one or more cavities are formed between the battery and the inner surface of the inner hollow structure; filling the one or more cavities with a heat transfer medium; and allowing the heat transfer fluid to flow through at least one channel located between the inner surface of the outer hollow structure and the outer surface of the inner hollow structure. The molding process may utilize one or a combination of blow molding, injection molding, compression molding, and rotational molding.

[0019] Optionally, the process may further include forming one or more structural elements in the inner hollow structure to support the weight of a battery or battery module or to act as bump stops to aid in the placement and retention of such a battery. These structural elements may be formed by a molding process such as blow molding utilizing, for example, "Ship-in-Bottle" (SIB) technology or "Tank Advance Process Technology (TAPT)."

[0020] Optionally, the process may further include forming one or more features protruding from the interior surface of the outer hollow structure or the exterior surface of the inner hollow structure into at least one channel to improve stiffness and / or to facilitate mixing of the fluids by directing fluid flow.

[0021] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples set forth herein are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. [Brief explanation of the drawings]

[0022] In order to provide a thorough understanding of the present disclosure, various embodiments will now be described by way of example only and with reference to the accompanying drawings, in which the components are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the present invention.

[0023] [Figure 1A] FIG. 1A is a schematic diagram showing a cutaway peripheral view of a battery pack including a battery within a double-walled enclosure formed in accordance with the teachings of the present disclosure. [Figure 1B] FIG. 1B is a cross-sectional view of the battery pack and enclosure of FIG. 1A taken along the x-axis. [Figure 2A] FIG. 2A is a cross-sectional view of another battery pack formed in accordance with the teachings of the present disclosure. [Figure 2B] FIG. 2B is a cross-sectional view of yet another battery pack formed in accordance with the teachings of the present disclosure. [Figure 3] FIG. 3 is a cross-sectional view of another battery pack and enclosure similar to that shown in FIG. 1B, where one or more structural supports are provided within the structure of the double-walled enclosure. [Figure 4A] FIG. 4A is a schematic diagram showing a cutaway peripheral view of a battery pack including a battery within another double-walled enclosure formed in accordance with the teachings of the present disclosure. [Figure 4B] FIG. 4B is a cross-sectional view of the battery pack and enclosure of FIG. 4A taken along the x-axis. [Figure 5] FIG. 5 is a perspective cross-sectional view of a portion of the enclosure highlighting fluid flow through protruding features into one or more channels of the enclosure. [Figure 6] FIG. 6 is a flow chart of a process for forming a battery pack including a battery within a double-walled enclosure in accordance with the teachings of the present disclosure.

[0024] These figures are provided for illustrative purposes only and are not intended to limit the scope of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following description is merely exemplary and is not intended to limit the present disclosure, its applications, or uses. For example, battery enclosures manufactured and used in accordance with the teachings described herein are described throughout this disclosure in the context of thermal management of batteries or battery packs in electric vehicles (EVs) or hybrid electric vehicles (HEVs) to more fully explain the structural elements and their uses. Incorporation and use of the battery enclosure in other applications, including, but not limited to, other electrical appliances or devices utilizing batteries or battery packs, is also considered within the scope of this disclosure. Furthermore, power electronic devices, such as metal-oxide semiconductor field-effect transistors (MOSFETs), gate-turn-off thyristors (GTOs), insulated-gate bipolar transistors (IGBTs), and integrated gate-commutated thyristors (IGCTs), are widely used to improve the efficiency of power delivery in fields such as consumer electronics, industrial equipment, communications equipment, transportation systems, and power grids, and could greatly benefit from the double-walled enclosure concepts described in this disclosure. It should be understood that corresponding reference numerals indicate like or corresponding parts and features throughout this specification and the drawings.

[0026] As used herein, the term "battery cell" refers to the basic electrochemical unit of a battery, including an anode and a cathode, as well as any components used to convert stored chemical energy into electricity, such as electrodes, separators, and electrolytes. In contrast, the terms "battery" or "battery module" refer to at least one battery cell contained within a housing, along with electrical connections and control and protection electronics. The term "battery pack" refers to a collection of multiple batteries, i.e., multiple battery modules, connected together in series or parallel to increase the voltage or capacity generated by the collection of batteries secured within the housing.

[0027] While embodiments are described herein to allow for a clear and concise specification, it is intended and will be understood that these embodiments may be combined or separated in various ways without departing from the scope of the invention. For example, it will be understood that all preferred features described herein are applicable to all aspects described herein.

[0028] The present disclosure provides a double-walled enclosure for thermal management of a battery. The double-walled enclosure typically includes an inner hollow structure housing one or more battery modules and an outer hollow structure surrounding or containing the inner hollow structure. One or more cavities are formed between the battery and an inner surface of the inner hollow structure. Similarly, at least one channel is formed between an outer surface of the inner hollow structure and the outer hollow structure. To provide thermal management for the battery, the at least one channel is configured to allow a heat transfer fluid to flow through it. The at least one channel may be located on the top of the battery, the bottom of the battery, one or more sides of the battery, or a combination thereof.

[0029] During operation, the cavity between the battery and the inner hollow structure may be filled with a heat transfer medium. Further, at least one channel contains a heat transfer fluid flowing therethrough. Heat generated by the battery is transferred via the heat transfer medium to the inner hollow structure, through the inner hollow structure, and to the heat transfer fluid flowing through at least one channel located between the inner hollow structure and the outer hollow structure.

[0030] The heat transfer medium may include, but is not limited to, a single-phase dielectric fluid, a multi-phase dielectric fluid, a phase change material, or a combination thereof. The phase change material may include, but is not limited to, paraffin, a sugar alcohol, a salt hydrate, or a combination thereof. Examples of single-phase dielectric fluids include, but are not limited to, Kryo51 and Kryo20 (LAUDA Dr. R. Wobser GmbH & Co. KG, Germany) and Xenitron 3221 (Croda International PLC, United Kingdom). Examples of multi-phase dielectric fluids include, but are not limited to, Novec 7000 (3M Company, United States). In a preferred design of the inner hollow structure, the amount of heat transfer medium required to fill the cavity may be minimized due to the cost and weight of the medium. While most designs of the double-walled enclosures in this disclosure are described as having a stationary heat transfer medium, those skilled in the art will understand that the heat transfer material may be circulated or flowing without departing from this disclosure.

[0031] The heat transfer fluid may include a heat transfer material that is liquid at normal ambient temperatures. The heat transfer fluid may include, but is not limited to, water, glycol, or a water / glycol mixture.

[0032] To facilitate the transfer of heat from the heat transfer medium to the heat transfer fluid, the inner hollow structure typically includes a polymer material so that the inner hollow structure is in thermal contact with the heat transfer fluid, thereby providing thermal management for the battery pack. The polymer material may include an elastomer, a thermoplastic resin, a thermoplastic elastomer (TPE), or a combination thereof. The TPE used as the polymer material may include, but is not limited to, a styrenic block copolymer (TPE-S), a polyolefin blend (TPE-O), a thermoplastic polyurethane (TPE-U), a thermoplastic polyester (TPE-E), a thermoplastic polyamide (TPE-A), or a mixture thereof. Alternatively, the thermoplastic resin used as the polymer material may include, but is not limited to, high-density polyethylene (HDPE), polypropylene (PP), polyamide (PA), polyethylene terephthalate (PET), or a mixture thereof. The polymer material is selected based on a combination of properties, including, but not limited to, hardness, cost, environmental impact, and available processing methods for forming the inner hollow structure. The type of polymer material selected for a particular application may influence the wall thickness of the inner hollow structure to ensure necessary or desired contact with the battery, heat transfer fluid, and / or outer hollow structure.

[0033] Optionally, the polymeric material may have a Shore A hardness in the range of about 40 to 100, or a Shore D hardness in the range of 20 to about 75. To improve thermal conductivity, the polymeric material may be a thermally conductive polymeric material. Generally, thermally conductive polymeric materials may include polymers having inherent thermal conductivity, blends of polymers where one or more polymers in the blend have inherent thermal conductivity, composite polymeric materials including at least one polymer configured as a polymer matrix and thermally conductive fillers dispersed in the polymer matrix, or combinations thereof.

[0034] Polymers with inherent thermal conductivity may be used alone, in blends with other polymers, or as at least part of a polymer matrix forming a composite polymer material. Thermally conductive polymer materials include, but are not limited to, thermally conductive epoxy resins, polyimides (PI), polyoxymethylene (POM), polycarbonates (PC), or other high-performance engineering polymers. Optionally, thermally conductive polymer materials may include conjugated polymers with rigid conjugated backbones and strong intermolecular π-π stacking interactions, such as diamine-cured epoxy resins with liquid crystalline structures containing biphenyl functional groups. The inherent thermal conductivity of thermally conductive polymer materials can be enhanced by creating physical structures based on the degree of crystallinity, crystal grain size, crystal grain (crystallite) orientation, molecular chain length, the degree of amorphous domain bonding with crystallites, etc., or by tailoring the functional structure of the polymer chains during polymer synthesis and processing.

[0035] When the thermally conductive polymer material used to form the inner hollow structure is a composite polymer material in which a thermally conductive filler is dispersed in a polymer matrix, the polymer matrix provides a relatively soft and flexible composite polymer material that enables efficient heat transfer. In this regard, the thermally conductive filler can provide good thermal conductivity, while the polymer matrix is ​​sufficiently soft and pliable to directly eliminate gaps and provide good physical contact between the surface of the inner hollow structure and the battery disposed therein, as well as between the heat transfer medium filling the cavity formed therein and the surface of the inner hollow structure. Alternatively, the polymer matrix may be a harder polymer material such as high-density polyethylene (HDPE) or polypropylene (PP). In this case, the heat transfer medium fills the cavity formed therein and provides good contact and heat transfer. Because the thermally conductive filler may exhibit low electrical conductivity, the use of a composite polymer material can also effectively provide electrical insulation for the battery pack.

[0036] Furthermore, by allowing a heat transfer fluid to flow through one or more channels between the inner hollow structure and the outer hollow structure, the material used to form the inner hollow structure and the outer hollow structure may change in volume by 20% or less, may change in volume by less than 15%, may change in volume by about 10% or less, or may change in volume by 5% or less.

[0037] While the double-walled enclosure of the present disclosure does not have the same thermal conductivity as conventional commercially available aluminum cooling plates, the thermal conductivity provided by the polymer material of the inner hollow structure and the presence of the heat transfer medium and fluid can provide the necessary or desired performance for battery pack thermal management while directly providing the necessary electrical insulation without the need for an additional insulating layer required with the use of conventional aluminum cooling plates. Furthermore, double-walled enclosures formed in accordance with the teachings of the present disclosure offer additional advantages over conventional cooling plates, such as reduced manufacturing costs, lighter weight, easier assembly, reduced likelihood of short circuits occurring within the battery pack, and in some cases (e.g., compared to the use of adhesive layers and polymer pads), easier recycling. The process of forming the double-walled enclosure opens up the possibility of commercially viable production of products for smaller markets due to tooling differences and lower investment costs required compared to the manufacturing processes associated with conventional cooling plates.

[0038] For purposes of this disclosure, the terms "about" and "substantially" as used herein in connection with measurable numbers and ranges refer to expected variations known to those of ordinary skill in the art (e.g., limits and variability of measurement).

[0039] For purposes of this disclosure, the terms "at least one" and "one or more of" may be used interchangeably and may be synonymous. These terms refer to the inclusion of a single element or multiple elements, which may be expressed by adding the suffix "(s)" after the element. For example, "at least one channel," "one or more channels," and "channel(s)" may be used interchangeably and intended to be synonymous.

[0040] 1A and 1B, a battery pack 1 is shown with one or more battery modules 10, each having a positive terminal 15 (+) and a negative terminal 15 (−) disposed within a double-walled enclosure 3. FIG. 1B shows a cross-sectional view of the battery pack of FIG. 1A taken along the x-axis. The double-walled enclosure 3 generally includes an inner hollow structure 7 or housing and an outer hollow structure 5 or housing that surrounds or encloses the inner hollow structure 7. One or more battery modules 10 are disposed within the inner hollow structure 7. One or more cavities 20 are formed between the battery 10 and an inner surface 8 of the inner hollow structure 7 and may be filled with a heat transfer medium 22. The one or more cavities 20 may be formed around a portion of the periphery of the battery 10 or, as shown in FIG. 1B, may be formed around the entire periphery of the battery 10. Additionally, at least one channel 25 is formed between the outer surface 9 of the inner hollow structure 7 and the inner surface 6 of the outer hollow structure 5. The at least one channel 25 may be filled with a heat transfer fluid 27 .

[0041] As shown in FIGS. 1A and 1B , to more fully describe the structure and use of the double-walled enclosure 3, most figures shown herein show at least one channel 25 disposed on the top of the battery 10 or battery module 10. Where no channel 25 exists between the inner hollow structure 7 and the outer hollow structure 5, the outer surface 8 of the inner hollow structure 7 contacts the inner surface 6 of the outer hollow structure 5. However, as shown in FIG. 2A , the at least one channel 25 may be disposed upside down, in which case the at least one channel 25 is disposed on the bottom of the battery 10 or battery module 10, or on both the top and bottom of the battery 10. Similarly, as shown in FIG. 2B , the at least one channel 25 may be disposed on one or more sides of the battery 10 or battery module 10 in the battery pack 1, as needed or desired for a particular application. Thus, the at least one channel 25 may be disposed on the top, bottom, one or more sides, or a combination thereof, of the battery 10 without departing from the scope of this disclosure.

[0042] As shown in FIGS. 1A, 1B, 2A, and 2B, the use of a polymer material to form the inner hollow structure 7 overcomes any inherent surface roughness or irregularities of the battery 10 and provides the inner surface 9 of the inner hollow structure 7 with sufficient ability to conformally establish contact with the battery 10 and / or to fully contact the heat transfer medium 22 present in the cavity 20 formed therebetween. Additionally, the outer surface 9 of the inner hollow structure 7 can maintain at least 50% surface contact with the heat transfer fluid 27 in at least one channel 25 disposed between the outer hollow structure 5 and the inner hollow structure 7. Alternatively, the surface contact maintained by the inner hollow structure 7 with the heat transfer fluid 27 can be between 50% and 100%, greater than 50% but less than 100%, between 55% and 95%, or from about 60% to about 90%. For purposes of this disclosure, the term "between" is intended to include the limits of the specified range.

[0043] 3, the inner hollow structure 7 may include one or more structural elements 30, 35 configured to support the weight of the battery or function as bump stops configured to assist in battery placement and retention. These structural elements 35 may be of the same composition as the inner hollow structure 7. Alternatively, the structural elements 30 may be of a different composition than the inner hollow structure 7. The structural elements 30, 35 may be integrally formed with the inner hollow structure 7 or may be formed as inserts connected to the inner hollow structure 7.

[0044] For purposes of this disclosure, the terms “integrally formed” or “integrally formed” mean that the structural element 35 and the inner hollow structure 7 are molded or formed as a single piece, and / or that the structural element 35 and the inner hollow structure 7 are formed separately and then joined to form a “leak-tight” hollow structure 7 using one or more of ultrasonic welding, spin welding, vibration welding, hot plate welding, infrared welding, laser welding, and an overmolding process. Alternatively, the structural element 35 may be formed as a single piece. Any process known to those skilled in the art capable of forming a single piece from a polymeric material may be used, including, but not limited to, injection molding or blow molding. Similarly, the inner hollow structure 7 and the outer hollow structure 5 may be integrally formed through the use of techniques such as, but not limited to, ship-in-bottle (SIB) technology or tank advance processing technology (TAPT) implemented via blow molding. Additional information regarding SIBs or TAPTs can be found in U.S. Patent Publication Nos. 2005 / 0040566, 2005 / 0040567, and 2021 / 0379811, each of which is incorporated by reference in its entirety. The use of TAPTs provides the added benefit of not exposing the battery pack to heat during the blow molding process.

[0045] The inner hollow structure 7 is formed to have a wall thickness ranging from about 0.3 millimeters (mm) to about 2.5 mm. Alternatively, the wall thickness may range from about 0.5 mm to about 2.3 mm, or from about 1.0 mm to about 2.0 mm. Similarly, the wall thickness of the outer hollow structure 5 ranges from about 1.0 mm to about 5.0 mm, or from about 1.5 mm to about 4.0 mm, to ensure the structural integrity of the double-walled enclosure 3. The wall thicknesses of the top, bottom, and / or sides of the inner hollow structure 7 and / or outer hollow structure 5 may be the same or different, depending on the structural design and manufacturing parameters used for a particular application. For example, the wall thickness may vary depending on the thickness required to provide sufficient rigidity to support the weight of the battery and to maintain stress levels within the inner hollow structure 7 and / or outer hollow structure 5 below the yield stress of the material used to form those structures 5, 7.

[0046] As shown in FIGS. 4A and 4B , a battery pack 1 similar to that shown in FIGS. 1A and 1B is provided, in which at least one sloped structural support 50 divides the channels 25, thereby allowing the heat transfer fluid 27 to flow in multiple directions. Those skilled in the art will understand that solid structural supports can be used in place of the sloped structural support 50 without departing from the scope of the present disclosure. However, the sloped structural support 50 design may be desirable depending on the type of manufacturing process (e.g., blow molding, etc.) selected to form the outer hollow structure 5. The use of the sloped structural support 50 design results in a small area (a) where heat transfer is severely restricted due to the lack of thermal contact between the outer surface 9 of the inner hollow structure 7 and the heat transfer fluid 27. The presence of this small area (a) does not affect the ability of the double-walled enclosure 3 to provide thermal management for the battery 10.

[0047] Referring to FIG. 5, a cross-sectional view of the battery pack 1 in the region of the channels 25 of FIGS. 4A and 4B is shown. In FIG. 5, the outer surface 9 of the inner hollow structure 7 is contoured, from which at least one feature 40 emanates and protrudes into at least one channel 25 to provide additional rigidity and guide or control the flow of the heat transfer fluid 27. Those skilled in the art will understand that these features 40 may protrude into one or more channels 25 from the outer surface 9 of the inner hollow structure 7 (see FIG. 4), the inner surface 6 of the outer hollow structure 5, or both surfaces 6, 9, without departing from the scope of this disclosure. The shape of the features 40 may be, but is not limited to, cylindrical, elliptical, or angular. The number, shape, and placement of the features 40 are selected to provide a desired flow and / or mixing of the heat transfer fluid 27 within the channels 25. In FIG. 5, the path (→) provides for fluid mixing in the presence of features 40 protruding into one or more channels 25. Heat transfer fluid 27 may include any type of heat transfer liquid, including, but not limited to, water, glycol, or a water / glycol mixture.

[0048] When the inner hollow structure 7 is formed of a thermally conductive polymer material, including a composite polymer material, the composite polymer material generally consists of, consists essentially of, or includes a thermally conductive filler dispersed within a polymer matrix. The thermally conductive filler may exhibit low electrical conductivity to aid in the electrical insulation of the battery. For purposes of this disclosure, a thermally conductive filler exhibiting low electrical conductivity is defined as 9.9×10 5 S / m order or less, or 9.9 x 10 4 The electrical conductivity of the thermally conductive filler is defined as being on the order of S / m or less. Alternatively, the electrical conductivity of the thermally conductive filler is low enough to be classified as an electrical insulator.

[0049] The thermally conductive filler comprises a plurality of particles, the composition of which includes boron nitride, alumina, aluminum nitride, silicon nitride, silicon carbide, graphene, graphite, carbon nanotubes (single-walled or multi-walled), or mixtures thereof. The particles may have shapes including, but not limited to, spherical, flat (e.g., platelet-like), irregular, or elongated (e.g., fibrous) shapes. The particles may be described as particles having any feasible crystalline morphology that provides thermal conductivity. Alternatively, boron nitride used as a thermally conductive filler provides desirable levels of thermal conductivity and electrical insulation for use in many applications. Boron nitride (BN) particles used as a thermally conductive filler may have either a hexagonal (H-BN) or cubic (C-BN) crystalline structure, and the thermally conductive filler may be H-BN.

[0050] The polymer matrix may comprise an elastomer, thermoplastic resin, or thermoplastic elastomer (TPE) having a Shore A hardness ranging from about 40 to 100, or a Shore D hardness ranging from 20 to about 75. Alternatively, the polymer matrix is ​​a thermoplastic elastomer (TPE), which may have a Shore A hardness ranging from about 50 to about 90, or a Shore D hardness ranging from about 45 to about 75, or a Shore A hardness ranging from about 70 to about 80. The Shore A hardness and / or Shore D hardness may be measured by the Shore® (Durometer) test according to ASTM D22440 00, ISO 7619, and ISO 868; DIN 53505; and / or JIS K 6301 (which has been replaced by JIS K 6253). Alternatively, the polymer matrix may be a thermoplastic resin having a Shore D hardness in the range of about 60-75.

[0051] According to one aspect of the present disclosure, the composition of the composite polymer material 70 includes a plurality of boron nitride particles dispersed within a thermoplastic elastomer (TPE) having a Shore A hardness ranging from about 70 to about 80.

[0052] The thermally conductive filler may be dispersed within the polymer matrix using any known mixing technique for dispersing solid particles in a liquid polymer. Upon mixing, the thermally conductive filler content ranges from about 5% to about 30% by weight, based on the total weight of the composite polymer material. Alternatively, the thermally conductive filler content may range from about 5% to about 25% by weight, or from about 10% to about 20% by weight, based on the total weight of the composite polymer material.

[0053] The outer hollow structure 5 is formed of a "hard" polymer to provide physical and mechanical protection for the battery pack. The outer hollow structure may include, but is not limited to, high density polyethylene (HDPE), polypropylene (PP), polyamide (PA), or combinations thereof as copolymers, polymer blends / mixtures, multilayer structures, or composites. The outer hollow structure may further include multiple fillers, such as fiber or particulate reinforcing materials (e.g., glass, carbon, etc.), which can improve structural performance and provide thermal runaway mitigation.

[0054] According to another aspect of the present disclosure, a battery pack with thermal management is provided. Referring again to Figures 1-5, the battery pack 1 generally includes at least one battery 10 and a double-walled enclosure 3 configured as described above and further defined in this section. The double-walled enclosure 3 may be used to provide thermal management for the at least one battery 10 in an electric vehicle (EV) or hybrid electric vehicle (HEV).

[0055] 6, according to another aspect of the present disclosure, there is provided a process 100 for forming a battery pack configured as described above and further defined herein. The process 100 generally includes providing a polymer material 105, molding an inner hollow structure from the polymer material 110, having an outer surface and an inner surface, molding an outer hollow structure 115, having an inner surface surrounding the outer surface of the inner hollow structure, wherein the outer surface of the inner hollow structure is in contact with the inner surface of the outer hollow structure or forms at least one channel with the inner surface of the outer hollow structure, providing at least one battery 120, assembling the at least one battery within the inner hollow structure 125 such that one or more cavities are formed between the battery and the inner surface of the inner hollow structure, filling the one or more cavities with a heat transfer medium 130, and allowing a heat transfer fluid to flow through at least one channel located between the inner surface of the outer hollow structure and the outer surface of the inner hollow structure 135. The molding process 120, 115 in this process may be one or a combination selected from the group consisting of blow molding, injection molding, compression molding, and rotational molding.

[0056] If desired, the process 100 may further include step 140 of forming one or more structural elements in the inner hollow structure to support the weight of the battery or battery module or to act as bump stops to aid in battery placement and retention. These structural elements may be formed by a molding process such as blow molding using, for example, Ship-in-Bottle (SIB) technology or Tank Advance Process Technology (TAPT).

[0057] If desired, the process 100 may further include forming 145A, 145B one or more features protruding from the interior surface 145A of the outer hollow structure or the exterior surface 145B of the inner hollow structure into at least one channel to improve stiffness and / or promote fluid mixing by directing fluid flow. This additional forming step 145A, 145B is typically incorporated into the molding process 110 by including an additional step in creating the mold used in the molding process, such as using 3D printing or placing an insert in the mold.

[0058] If desired, step 125 of assembling at least one battery in the inner hollow structure may be performed in combination with step 110 of molding the inner hollow structure using the "Ship-in-Bottle (SIB)" technique or "Tank Advance Processing Technology (TAPT)" during blow molding. Alternatively, assembling step 125 may include disposing one or more battery modules within the inner hollow structure having an opening. After disposing the battery, the opening is closed using any one or more of ultrasonic welding, spin welding, vibration welding, hot plate welding, infrared welding, laser welding, and overmolding techniques to form a "leak-tight" hollow structure. The one or more battery modules disposed within the inner hollow structure may have any known cell format, including, but not limited to, prismatic, cylindrical, pouch, or a combination thereof.

[0059] Those skilled in the art will understand that the process steps of the method described above and in Figure 6, as well as those further defined in this section, are not limited to being performed in the order described, but may be performed in any desired or necessary order based on the selection of materials and the manufacturing equipment and techniques selected for processing the materials. Each process step may be performed sequentially or simultaneously, and such steps may be combined and coordinated or performed as part of other process steps. Alternatively, if desired, the process steps may be performed in the order provided.

[0060] Given this disclosure, one of ordinary skill in the art will recognize that many changes can be made to the specific embodiments disclosed herein and still obtain like or similar results without departing from or exceeding the spirit or scope of the present disclosure. One of ordinary skill in the art will recognize that any property described herein is a property that is routinely measured and can be obtained by several different methods. The methods described herein are representative of such and other methods, and other methods may be used without departing from the scope of the present disclosure.

[0061] The foregoing description of various aspects of the present invention has been presented for purposes of illustration and description. It is not exhaustive and is not intended to limit the invention to the precise form disclosed. Many modifications or variations are possible in light of the above teachings. The form discussed was chosen and described in order to best illustrate the principles of the invention and its practical application, thereby enabling those skilled in the art to utilize the invention in various forms and with various modifications suited to the particular use contemplated. Therefore, the present invention is not limited to the preferred exemplary embodiment described above. Rather, numerous variations utilizing the illustrated solutions are possible, even in fundamentally different embodiments. All such modifications and variations are within the scope of the present invention, as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

1. 1. A double-walled enclosure for thermal management of a battery pack, comprising: an inner hollow structure having an inner surface and an outer surface; One or more battery modules are disposed within the inner hollow structure; an outer hollow structure having an inner surface; The outer surface of the inner hollow structure is in contact with the inner surface of the outer hollow structure, or the outer surface of the inner hollow structure forms at least one channel with the inner surface of the outer hollow structure through which a heat transfer fluid flows; the inner hollow structure comprises a polymer material such that the inner hollow structure is in thermal contact with the heat transfer fluid to provide the thermal management of the battery pack; Double walled enclosure.

2. the inner hollow structure has a wall thickness in the range of about 0.3 millimeters (mm) to about 2.5 mm; the outer hollow structure has a wall thickness ranging from about 1.0 mm to about 5.0 mm; The double-walled enclosure of claim 1 .

3. one or more cavities are formed between the one or more battery modules and the inner surface of the inner hollow structure; the one or more cavities are at least partially filled with a heat transfer medium; A double-walled enclosure according to claim 1 or 2.

4. the heat transfer medium in the one or more cavities is a single-phase dielectric fluid, a multi-phase dielectric fluid, a phase change material, or a combination thereof; the heat transfer fluid in the at least one channel is either water, glycol, or a water / glycol mixture; 4. The double-walled enclosure of claim 3.

5. The polymeric material comprises an elastomer, a thermoplastic, a thermoplastic elastomer (TPE), or a combination thereof. A double-walled enclosure according to any one of claims 1 to 4.

6. The polymeric material has a Shore A hardness in the range of about 40 to 100, or a Shore D hardness in the range of 20 to about 75. A double-walled enclosure according to any one of claims 1 to 5.

7. the polymer material is a thermally conductive polymer material; A double-walled enclosure according to any one of claims 1 to 6.

8. The thermally conductive polymeric material includes a polymer having an inherent thermal conductivity, a blend of polymers in which one or more polymers in the blend have an inherent thermal conductivity, a composite polymeric material comprising at least one polymer configured as a polymer matrix and a thermally conductive filler dispersed in the polymer matrix, or a combination thereof.

8. The double-walled enclosure of claim 7.

9. the thermally conductive filler comprises a plurality of particles having a composition selected from the group consisting of boron nitride, alumina, aluminum nitride, silicon nitride, silicon carbide, graphene, carbon nanotubes, or mixtures thereof; 9. The double-walled enclosure of claim 8.

10. The polymeric material composition comprises a composite polymeric material containing a plurality of boron nitride particles dispersed in a thermoplastic elastomer (TPE) matrix having a Shore A hardness ranging from about 70 to about 80. A double-walled enclosure according to any one of claims 1 to 6.

11. the outer hollow structure comprises high density polyethylene (HDPE), polypropylene (PP) or polyamide (PA), or a combination thereof, either as a copolymer, polymer blend / mixture, multilayer structure or composite material; A double-walled enclosure according to any one of claims 1 to 10.

12. the at least one channel is located above, below, at least one side of, or a combination thereof with respect to the one or more battery modules; A double-walled enclosure according to any preceding claim.

13. the inner hollow structure includes one or more structural elements that function as bump stops configured to support the weight of the one or more battery modules and / or assist in battery placement and retention; the one or more structural elements are formed integrally with the inner hollow structure or as an insert connected to the inner hollow structure; A double-walled enclosure according to any preceding claim.

14. at least one of the exterior surface of the inner hollow structure or the interior surface of the outer hollow structure includes one or more features configured to increase stiffness and / or to promote mixing of fluids by directing fluid flow; the at least one feature projects into the at least one channel; A double-walled enclosure according to any preceding claim.

15. at least a portion of the exterior surface of the inner hollow structure forming a portion of the at least one channel is flat so as to maintain at least 50% surface contact with the heat transfer fluid within the at least one channel; A double-walled enclosure according to any preceding claim.

16. the inner hollow structure and the outer hollow structure permitting the heat transfer fluid to flow through the at least one channel to undergo a volume change of less than about 15%. A double-walled enclosure according to any preceding claim.

17. The thermally conductive polymer material comprises a composite polymer material having a polymer matrix with a thermally conductive filler dispersed therein, such that the content of the thermally conductive filler ranges from about 5 wt % to about 25 wt % based on the total weight of the composite polymer material. A double-walled enclosure according to any one of claims 7 to 9.

18. 1. A battery pack with thermal management, comprising: at least one battery; a double-walled enclosure according to any one of claims 1 to 17; The double-walled enclosure comprises: an inner hollow structure having an inner surface and an outer surface; One or more battery modules are disposed within the inner hollow structure; an outer hollow structure having an inner surface; The outer surface of the inner hollow structure is in contact with the inner surface of the outer hollow structure, or the outer surface of the inner hollow structure forms at least one channel with the inner surface of the outer hollow structure through which a heat transfer fluid flows; the inner hollow structure comprises a polymer material such that the inner hollow structure is in thermal contact with the heat transfer fluid to provide the thermal management of the battery pack; Battery pack.

19. the polymeric material comprises a thermally conductive polymeric material; 20. The battery pack of claim 18.

20. the thermally conductive polymer material includes a composite polymer material having a polymer matrix with a thermally conductive filler dispersed therein; the thermally conductive filler comprises a plurality of particles having a composition selected from the group consisting of boron nitride, alumina, silicon nitride, graphene, carbon nanotubes, or mixtures thereof; the polymer matrix is ​​an elastomer, thermoplastic or thermoplastic elastomer (TPE) having a Shore A hardness in the range of about 40 to 100, or a Shore D hardness in the range of 20 to about 75; The content of the thermally conductive filler ranges from about 5 wt % to about 25 wt %, based on the total weight of the composite polymer material.

20. The battery pack of claim 19.

21. Use of a double-walled enclosure according to any of claims 1 to 17 to provide thermal management of one or more battery modules in an electric vehicle (EV) or hybrid electric vehicle (HEV).

22. A process for forming a battery pack according to any one of claims 18 to 20 configured for thermal management, comprising: providing a polymeric material; molding an inner hollow structure from said polymeric material; wherein the inner hollow structure has an outer surface and an inner surface; forming an outer hollow structure having an interior surface surrounding the exterior surface of the inner hollow structure; wherein the outer surface of the inner hollow structure is in contact with the inner surface of the outer hollow structure, or the outer surface of the inner hollow structure forms at least one channel with the inner surface of the outer hollow structure; providing at least one battery; assembling at least one battery within the inner hollow structure such that one or more cavities are formed between the battery and the interior surface of the inner hollow structure; filling the one or more cavities with a heat transfer medium; and allowing a heat transfer fluid to flow through the at least one channel located between the interior surface of the outer hollow structure and the exterior surface of the inner hollow structure. process.

23. The molding is carried out using a method selected from the group consisting of blow molding, injection molding, compression molding, rotational molding, or a combination thereof; 23. The process of claim 22.

24. forming one or more structural elements in the inner hollow structure configured to support the weight of the battery and / or to function as bump stops, the one or more structural elements being of the same or different composition as the composition of the inner hollow structure; and / or forming one or more features protruding from the interior surface of the outer hollow structure or the exterior surface of the inner hollow structure into the at least one channel; the features are configured to increase stiffness and / or to promote mixing of the fluid by directing fluid flow; 24. The process of claim 22 or 23.

25. The molding method includes using "Ship-in-Bottle (SIB)" technology or "Tank Advance Process Technology (TAPT)" A process according to any one of claims 22 to 24.

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