Traction battery insulator assembly with encapsulated structural body

Abstract

A traction battery assembly includes a plurality of battery cells arranged in a linear array, a substrate supporting the array, and an insulator assembly. The insulator assembly includes outer compressible layers, at least one thermal insulation layer, and a metal layer.The metal layer includes a metal plate encapsulated in a dielectric material such that all surfaces of the metal plate are covered by the dielectric material, the layers secured together to form a unitary stack, the metal layer being disposed against and with the at least one thermal insulation layer, the at least one thermal insulation layer being disposed between the outer compressible layers, and the insulator assembly being disposed between an adjacent pair of the battery cells and received on the substrate such that a portion of the dielectric material lies between the substrate and the metal plate.

Description

FIELD OF TECHNOLOGY

[0001] The present disclosure relates to traction battery assemblies for motor vehicles and, more particularly, to insulator assemblies disposed within the battery array. GENERAL STATE OF THE ART

[0002] Vehicles, such as battery electric vehicles and hybrid electric vehicles, include a traction battery assembly that acts as the power source for the vehicle. The traction battery may include components and systems to help manage the vehicle's power and operation. The traction battery may also include high-voltage components and may include an air or liquid thermal management system to control the battery's temperature. SUMMARY

[0003] According to one embodiment, a traction battery assembly includes a plurality of battery cells arranged in a linear array, a substrate supporting the array, and an insulator assembly. The insulator assembly includes outer compressible layers, at least one thermal insulation layer, and a metal layer.The metal layer includes a metal plate encapsulated in a dielectric material such that all surfaces of the metal plate are covered by the dielectric material, the layers secured together to form a unitary stack, the metal layer being disposed against and with the at least one thermal insulation layer, the at least one thermal insulation layer being disposed between the outer compressible layers, and the insulator assembly being disposed between an adjacent pair of the battery cells and received on the substrate such that a portion of the dielectric material lies between the substrate and the metal plate.

[0004] According to another embodiment, a traction battery assembly includes a substrate, an array of battery cells disposed on the substrate, and an insulator assembly. The insulator assembly includes a stack of: first and second outer compressible planar bodies; first and second planar thermal insulation bodies disposed between the first and second outer bodies; and a planar structural body including a metal plate encapsulated in a dielectric material such that all surfaces of the metal plate are covered by the dielectric material. The structural body has a first side disposed against the first thermal insulation body and a second side disposed against the second thermal insulation body.The insulator assembly is disposed between an adjacent pair of battery cells and is received on the substrate such that a portion of the dielectric material lies between the substrate and the metal plate.

[0005] According to yet another embodiment, a method includes stacking a metal plate onto a first foil of dielectric material, the metal plate and the first foil having substantially the same cross-sectional area; trimming an entire perimeter of the metal plate to expose an edge portion of the first foil, the edge portion completely circumscribing the perimeter of the metal plate; disposing a second foil over the metal plate, the second foil having substantially the same cross-sectional area as the first foil; adhering the second foil to the first foil to completely encapsulate the metal plate, forming a structural body; and stacking the structural body, the first and second outer compressible bodies, and at least one thermal insulation body to form an insulator assembly. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram of an exemplary hybrid vehicle. Fig. 2 is a side view of a battery array. Fig. 3 is an exploded view of an insulator assembly. Fig. 4 is a perspective view of the insulator assembly. Fig. 5 is a side view of the insulator assembly installed on a substrate of the battery assembly, with other components of the battery array omitted for illustrative purposes. Fig. 6 is a schematic view of a process for manufacturing a metal layer of the insulator assembly and assembling the insulator assembly. DETAILED DESCRIPTION

[0006] This specification describes embodiments of the present disclosure. It should be understood, however, that the disclosed embodiments are merely examples, and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or reduced to show details of specific components. Therefore, specific structural and functional details disclosed in this specification are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.It will be understood by those of ordinary skill in the art that various features illustrated and described with reference to any of the figures may be combined with features illustrated in one or more other figures to produce embodiments not explicitly illustrated or described. The illustrated combinations of features provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of this disclosure may be desirable for particular applications or implementations.

[0007] Fig. 1 depicts a schematic representation of a plug-in hybrid-electric vehicle (PHEV). However, certain embodiments may also be implemented in the context of non-plug-in hybrid vehicles and fully electric vehicles. The vehicle 12 includes one or more electric machines 14 mechanically connected to a hybrid transmission 16. The electric machines 14 may be capable of operating as an electric motor or generator. Furthermore, the hybrid transmission 16 may be mechanically connected to an engine 18. The hybrid transmission 16 may also be mechanically connected to a driveshaft 20 that is mechanically connected to the wheels 22. The electric machines 14 may provide propulsion and braking functions when the engine 18 is on or off.The electric machines 14 also function as generators and can provide fuel efficiency benefits by recovering energy through regenerative braking. The electric machines 14 reduce pollutant emissions and increase fuel efficiency by reducing the workload on the engine 18.

[0008] A traction battery or battery pack 24 stores energy that can be used by the electric machines 14. The traction battery 24 typically provides a high-voltage direct current (DC) output from one or more battery cell arrays, sometimes referred to as battery cell stacks, within the traction battery 24. The battery cell arrays include one or more battery cells.

[0009] Battery cells, such as prismatic cells, pouch cells, cylindrical cells, or any other cell type, convert stored chemical energy into electrical energy. The cells may contain a casing, a positive electrode (cathode), and a negative electrode (anode). An electrolyte allows ions to move between the anode and cathode during discharge and then back again during recharging. Terminals may allow current to flow out of the cell for use by the vehicle.

[0010] Different battery pack configurations may be available to suit individual vehicle variables, including installation constraints and power requirements. The battery cells can be thermally regulated using a thermal management system. Examples of thermal management systems include air cooling systems, liquid cooling systems, and a combination of an air and liquid cooling system.

[0011] The traction battery 24 may be electrically connected to one or more power electronics modules 26 through one or more contactors (not shown). The one or more contactors isolate the traction battery 24 from other components when open and connect the traction battery 24 to other components when closed. The power electronics module 26 may be electrically connected to the electric machines 14 and may provide the ability to transfer electrical energy bidirectionally between the traction battery 24 and the electric machines 14. For example, a typical traction battery 24 may provide a DC voltage, while the electric machines 14 may require a three-phase alternating current (AC) voltage to operate.The power electronics module 26 can convert the DC voltage into a three-phase AC voltage as required by the electric machines 14. In a regeneration mode, the power electronics module 26 can convert the three-phase AC voltage from the electric machines 14, which act as generators, into the DC voltage required by the traction battery 24. The description in this document applies equally to all-electric vehicles. In an all-electric vehicle, the hybrid transmission 16 can be a gear box connected to an electric machine 14, and the motor 18 is not present.

[0012] In addition to providing power for propulsion, the traction battery 24 can provide power for other vehicle electrical systems. A typical system may include a DC / DC converter module 28 that converts the high-voltage DC output of the traction battery 24 into a low-voltage DC supply compatible with other vehicle components. Other high-voltage loads, such as compressors and electric heaters, may be directly connected to the high-voltage supply without the use of a DC / DC converter module 28. In a typical vehicle, the low-voltage systems are electrically connected to an auxiliary battery 30, such as a 12-volt battery.

[0013] A battery energy control module (BECM) 33 may be in communication with the traction battery 24. The BECM 33 may function as a controller for the traction battery 24 and may also include an electronic monitoring system that manages the temperature and state of charge of each of the battery cells. The traction battery 24 may include a temperature sensor 31, such as a thermistor or other temperature indicator. The temperature sensor 31 may be in communication with the BECM 33 to provide temperature data regarding the traction battery 24.

[0014] The vehicle 12 may be recharged by a charging station connected to an external power source 36. The external power source 36 may be electrically connected to an electric vehicle supply equipment (EVSE) 38. The external power source 36 may provide DC or AC electrical power to the EVSE 38. The EVSE 38 may have a charging connector 40 for plugging into a charging port 34 of the vehicle 12. The charging port 34 may be any type of connector configured to transfer power from the EVSE 38 to the vehicle 12. The charging port 34 may be electrically connected to a charging device or an on-board power conversion module 32. The power conversion module 32 may condition the power supplied by the EVSE 38 to provide the proper voltage and current levels to the traction battery 24.The power conversion module 32 may interface with the EVSE 38 to coordinate power delivery to the vehicle 12. The EVSE connector 40 may have pins that mate with corresponding recesses of the charging port 34.

[0015] The various components discussed may have one or more associated controllers for controlling and monitoring the operation of the components. The controllers may communicate via a serial bus, such as a Controller Area Network (CAN), or via dedicated electrical wiring.

[0016] With reference to Fig. 2, the traction battery assembly 24 includes one or more battery arrays 52, each having a plurality of battery cells 54 arranged in a stack. It is understood that the battery 24 may include one, two, three, four, or more arrays or stacks of battery cells and associated components.

[0017] Each of the battery cells 54 may have opposing main sides 56. The cells may be pouch cells, prismatic cells, or the like. Terminals 60 extend from the secondary side(s) 58. Each cell 54 may have two terminals 60, e.g., a positive terminal and a negative terminal, with the positive and negative terminals extending from a different secondary side 58. In other embodiments, the terminals may be located on the same secondary side.

[0018] The array 52 may be held together by a pair of end plates and rails or other clamping elements (not shown) connecting the end plates to provide compression and retention of the cells. Each end plate may be adjacent to the main side 56 of the first or last cell. The arrays 52 may include additional support structure, insulator assemblies (described below), or cooling features. The traction battery 24 may include more or fewer of the battery arrays 52 described above depending on power requirements, installation constraints, the desired electric range of the vehicle, and other factors.

[0019] The cells 54 in each array 52 may be wired in series, parallel, or a combination thereof. If more than one array is provided, the arrays may be connected in series, parallel, or a combination thereof. The battery cells 54 may be electrically connected to one another with one or more busbars.

[0020] Each array includes one or more insulator assemblies 70 disposed between an adjacent pair of cells 54. The insulator assemblies 70 may be interleaved with the battery cells 54 at regular intervals. In the illustrated embodiment, one insulator assembly 70 is provided every two cells. That is, within the array 52, two battery cells 54, one insulator assembly 70, two battery cells, etc. alternate. However, this is merely an exemplary embodiment. In some embodiments, three or more cells may be stacked together between each of the insulator assemblies 70. In other embodiments, the battery cells and insulator assemblies 70 may alternate individually. The insulator assemblies 70 serve several purposes, including thermal insulation, compressibility to accommodate sizing tolerances, and isolating the groups of cells from one another.

[0021] Each of the battery cell arrays 52, including the cells 54 and the insulator assembly 70, is supported by a substrate 72. The substrate 72 may be a tray of a battery casing or may be a cold plate or other cooling device.

[0022] With reference to Fig. 3 through 5, each insulator assembly 70 may be formed by a stack of a plurality of bodies or layers. In the illustrated embodiment, the insulator assembly 70 includes a first outer layer 74 and a second outer layer 76. The outer layers 74, 76 may be formed from compressible bodies having a planar shape that matches or substantially matches the size of the battery cells 54. For example, the outer layer 74, 76 may be thin or sheet-like rectangular prisms having major sides 84 that are much wider than a thickness of the minor sides 86. The compressible bodies may be formed from foam or other compressible material.

[0023] Between the first and second outer layers 74, 76 lie at least one thermal insulation layer 77 and a structural layer, e.g., a metal layer 82. In the illustrated embodiment, a plurality of thermal insulation layers 77 are provided, with at least one insulation layer on both sides of the metal layer 82. As shown in the example, one grouping of thermal insulation layers 78 is provided between the outer layer 74 and the metal layer 82, and another grouping of thermal insulation layers 80 is provided between the metal layer 82 and the outer layer 76. In the illustrated example, each grouping 78, 80 includes two insulation layers, but in other embodiments, additional or fewer layers may be provided.Each of the insulation layers 77 may be the same or they may be different types of insulation layers provided within each of the groups 78, 80.

[0024] The thermal insulation layers reduce heat transfer between adjacent cells. The thermal insulation layer 77 can be formed from mica, aerogel, or any other suitable insulator. Each thermal insulation layer 77 can be a planar sheet-like body having major sides 88 and minor sides 90.

[0025] The metal layer 82 may include a metal plate 92 encapsulated in a dielectric material 94 that completely surrounds the metal plate 82 such that all surfaces of the metal plate 92 are encapsulated. The metal layer may be made of steel (e.g., stainless or non-stainless), copper, aluminum, or another suitable metal. The metal layer 82 provides structural rigidity, puncture resistance, and heat dissipation to the assembly 70. The inclusion of the metal layer 82 may result in a thinner assembly 72 and increase the heat dissipation capability of the metal plate 82, allowing a reduction in the thickness or number of insulation layers. The dielectric layers may be a polymer, such as a polymer including polyimide. Other examples include PET or other thermoplastics.

[0026] The fully encapsulated dielectric material 94 can further reduce the weight and thickness of the metal layer 82. This configuration can also allow for a thinner metal layer, e.g., 0.04 millimeters (mm) compared to 0.1 mm, thereby reducing the weight and thickness of the assembly 70. The fully encapsulated dielectric material 94 can also prevent direct contact with the metal and covers any rough edges or burrs that may have formed on the metal during the manufacturing process.

[0027] The metal layer 82 has major sides 104 and minor sides 106 defined by the dielectric material 94. The metal layer 82 is sandwiched between the insulating layers 78 and 80, with the major side 88 of the insulating body 110 positioned against the major side 106 of the metal layer 82, and with the major side 88 of the insulating body 112 positioned against the other major side 106 of the metal layer 82.

[0028] The dielectric material 94 allows the metal layer 82 to be received directly on the substrate 72, with the bottom surface 100 positioned against a top surface of the substrate 102. The substrate 72 may be made of metal, such as a metal tub or a metal cold plate (e.g., a liquid-cooled heat exchanger), and the dielectric material 94 electrically insulates the metal layer 82 from the substrate 72.

[0029] Fig.6 illustrates an exemplary manufacturing process 200 for producing the metal layer of the insulator assembly and for assembling the stack. In a first step (not shown), a first foil or sheet of dielectric material 210 is cut. In the illustrated embodiment, the dielectric material 210 is cut into a rectangular shape having a length 212 and a width 214. In step 202, a metal plate 216 is stacked onto the dielectric material 210. The metal plate 216 is substantially the same size as the dielectric material 210, which has the same length 212 and the same width 214. That is, the metal plate 216 and the dielectric material 210 have substantially the same cross-sectional area. As used herein, "substantially" means within 3 percent.

[0030] In step 204, the metal plate 216 is trimmed around its entire circumference to expose an edge portion 218 of the first foil 210. The edge portion 218 completely circumscribes the circumference of the metal plate 216.

[0031] In step 206, a second sheet of dielectric material 220 is placed on top of the metal plate 216 to form a stack, with the metal plate 216 sandwiched between the first and second sheets of dielectric material 210, 220. The second sheet 220 has substantially the same length 212 and width 214 as the first sheet. That is, the first and second sheets have substantially the same cross-sectional area so that the edges 222 of the sheets are aligned when stacked at operation 206. The edge portions 218 that are outside the perimeter of the metal plate 216 come together to form an area to adhere the first and second sheets to each other to completely encapsulate the metal plate 216. After step 206, a fully formed metal layer is produced.

[0032] In step 208, the fully formed metal layer is stacked with the other components of the insulator assembly, which are then all secured together to form the final insulator assembly that can be integrated into a battery array. For example, in step 208, the metal layer is placed between first and second outer compressible bodies, with at least one thermal insulation body sandwiched between one of the compressible bodies and the metal layer. In another example, the metal layer is sandwiched between first and second insulation bodies framed by first and second outer compressible bodies to form the insulator assembly stack.

[0033] All of these layers of the insulator assembly are joined together to form a cohesive unit. For example, an adhesive or double-sided tape may be applied between each of the different layers of the insulator assembly. Alternatively, the layers may be bonded or otherwise secured by mechanical means.

[0034] Although exemplary embodiments are described above, these embodiments are not intended to describe all possible forms encompassed by the claims. The terms used in the specification are terms of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As described above, the features of various embodiments may be combined to form further embodiments of the invention that may not be expressly described or illustrated.While various embodiments may have been described as advantageous or preferred over other prior art embodiments or implementations with respect to one or more desired characteristics, one of ordinary skill in the art will recognize that one or more features or characteristics may be compromised to achieve the desired overall system attributes, depending on the specific application and implementation. These attributes may include, but are not limited to, strength, durability, marketability, appearance, buildability, size, serviceability, weight, manufacturability, ease of assembly, etc. Accordingly, embodiments described as less desirable than other prior art embodiments or implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.

[0035] According to the present invention, a traction battery assembly is provided, comprising: a plurality of battery cells arranged in a linear array; a substrate supporting the array;and an insulator assembly including: outer compressible layers, at least one thermal insulation layer, and a metal layer including a metal plate encapsulated in a dielectric material such that all surfaces of the metal plate are covered by the dielectric material, the layers secured together to form a unitary stack, the metal layer being disposed against the at least one thermal insulation layer and with the metal layer, the at least one thermal insulation layer being disposed between the outer compressible layers, and the insulator assembly being disposed between an adjacent pair of the battery cells and received on the substrate such that a portion of the dielectric material lies between the substrate and the metal plate.;

[0036] According to one embodiment, the insulator assembly further includes a second thermal insulation layer disposed against the metal layer opposite the at least one thermal insulation layer.

[0037] According to one embodiment, the at least one thermal insulation layer is a plurality of thermal insulation layers arranged between the metal layer and one of the outer layers.

[0038] According to one embodiment, the dielectric material is a polymer.

[0039] In one embodiment, the polymer comprises polyimide.

[0040] According to one embodiment, the metal plate is made of steel.

[0041] According to one embodiment, the insulator assembly is a plurality of insulator assemblies, and each of the plurality of insulator assemblies is disposed between an adjacent pair of the battery cells.

[0042] According to one embodiment, the substrate is a tray of a battery housing.

[0043] According to one embodiment, the substrate is a cold plate.

[0044] According to one embodiment, the metal layer is secured to the at least one thermal insulation layer by adhesive.

[0045] According to the present invention, a traction battery assembly is provided, comprising: a substrate; an array of battery cells disposed on the substrate;and an insulator assembly including a stack of: first and second outer compressible planar bodies, first and second planar thermal insulation bodies disposed between the first and second outer bodies, and a planar structural body including a metal plate encapsulated in a dielectric material such that all surfaces of the metal plate are covered by the dielectric material, the structural body having a first side disposed against the first thermal insulation body and a second side disposed against the second thermal insulation body, the insulator assembly being disposed between an adjacent pair of the battery cells and received on the substrate such that a portion of the dielectric material lies between the substrate and the metal plate.;

[0046] According to one embodiment, the structural body is joined to the first and second thermal insulation bodies.

[0047] According to one embodiment, the insulator assembly further includes a third planar thermal insulation body joined to the first outer body and disposed between the first planar thermal insulation body and the first outer body.

[0048] According to one embodiment, the compressible planar bodies are foam bodies.

[0049] According to one embodiment, the planar thermal insulation bodies are formed from mica or aerogel.

[0050] According to one embodiment, the dielectric material is a polymer.

[0051] According to the present invention, a method includes: stacking a metal plate on a first foil of dielectric material, the metal plate and the first foil having a substantially equal cross-sectional area; trimming an entire perimeter of the metal plate to expose an edge portion of the first foil, the edge portion completely circumscribing the perimeter of the metal plate; disposing a second foil over the metal plate, the second foil having a substantially equal cross-sectional area as the first foil; adhering the second foil to the first foil to completely encapsulate the metal plate, forming a structural body; and stacking the structural body, the first and second outer compressible bodies, and at least one thermal insulation body to form an insulator assembly.

[0052] In one aspect of the invention, the method includes: assembling a battery array by arranging battery cells in an array and placing the insulator assembly between an adjacent pair of the battery cells.

[0053] In one aspect of the invention, the first and second films are made of the same material.

[0054] In one aspect of the invention, the first and second films comprise polyimide.

Claims

[1] Traction battery assembly comprising: a plurality of battery cells arranged in a linear array; a substrate supporting the array; and an insulator assembly that includes: outer compressible layers, at least one thermal insulation layer and a metal layer including a metal plate encapsulated in a dielectric material such that all surfaces of the metal plate are covered by the dielectric material, the layers secured together to form a unitary stack, the metal layer being disposed against and with the at least one thermal insulation layer, the at least one thermal insulation layer being disposed between the outer compressible layers, and the insulator assembly being disposed between an adjacent pair of the battery cells and received on the substrate such that a portion of the dielectric material lies between the substrate and the metal plate. [2] The traction battery assembly of claim 1, wherein the insulator assembly further includes a second thermal insulation layer disposed against the metal layer opposite the at least one thermal insulation layer. [3] The traction battery assembly of claim 1, wherein the at least one thermal insulation layer is a plurality of thermal insulation layers disposed between the metal layer and one of the outer layers. [4] The traction battery assembly of claim 1, wherein the dielectric material is a polymer. [5] The traction battery assembly of claim 4, wherein the polymer includes polyimide. [6] The traction battery assembly of claim 1, wherein the metal plate is made of steel. [7] The traction battery assembly of claim 1, wherein the insulator assembly is a plurality of insulator assemblies, and each of the plurality of insulator assemblies is disposed between an adjacent pair of the battery cells. [8] The traction battery assembly of claim 1, wherein the substrate is a tray of a battery housing. [9] The traction battery assembly of claim 1, wherein the substrate is a cold plate. [10] The traction battery assembly of claim 1, wherein the metal layer is secured to the at least one thermal insulation layer by adhesive. [11] Traction battery assembly comprising: a substrate; an array of battery cells arranged on the substrate; and an insulator assembly comprising a stack of: a first and a second outer compressible planar body, a first and a second planar thermal insulation body arranged between the first and the second outer body, and a planar structural body including a metal plate encapsulated in a dielectric material such that all surfaces of the metal plate are covered by the dielectric material, the structural body having a first side disposed against the first thermal insulation body and a second side disposed against the second thermal insulation body, and the insulator assembly is disposed between an adjacent pair of the battery cells and received on the substrate such that a portion of the dielectric material lies between the substrate and the metal plate. [12] The traction battery assembly according to claim 11, wherein the structural body is joined to the first and second thermal insulation bodies. [13] The traction battery assembly of claim 11, wherein the insulator assembly further includes a third planar thermal insulation body joined to the first outer body and disposed between the first planar thermal insulation body and the first outer body. [14] A traction battery assembly according to claim 11, wherein the compressible planar bodies are foam bodies, wherein the planar thermal insulation bodies are formed of mica or aerogel. [15] Procedure comprising: Stacking a metal plate on a first foil of dielectric material, the metal plate and the first foil having a substantially equal cross-sectional area; trimming an entire circumference of the metal plate to expose an edge portion of the first foil, the edge portion completely circumscribing the circumference of the metal plate; disposing a second foil over the metal plate, the second foil having a substantially equal cross-sectional area as the first foil; Adhering the second film to the first film to completely encapsulate the metal plate, forming a structural body; and Stacking the structural body, the first and second outer compressible bodies, and at least one thermal insulation body to form an insulator assembly.

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