THERMAL BLOCK FOR TRACTION BATTERY PACK

Abstract

A traction battery pack assembly comprises a cell stack within an interior of an enclosure. The cell stack includes a plurality of battery cells arranged along a cell stack axis and at least one thermal barrier also arranged along the cell stack axis. The at least one thermal barrier has a plurality of more compressible parts attached to a plurality of less compressible parts to form at least one channel configured to direct a liquid coolant through the cell stack.

Description

AREA OF TECHNOLOGY

[0001] This disclosure describes in detail exemplary assemblies that guide liquid coolant within a battery pack, and in particular thermal barriers that guide the liquid coolant between cells of a cell stack. GENERAL STATE OF THE ART

[0002] Electrified vehicles differ from conventional motor vehicles in that they incorporate a powertrain featuring one or more electric motors. These electric motors can power the vehicles instead of, or in addition to, an internal combustion engine. A traction battery pack assembly can supply power to the electric motors. As part of an immersion heat management system, liquid coolant can be circulated through the traction battery pack to help regulate thermal energy within it. SUMMARY

[0003] In some aspects, the techniques described herein relate to a traction battery pack assembly comprising: a cell stack within an interior of an enclosure, wherein the cell stack comprises a plurality of battery cells arranged along a cell stack axis, and at least one thermal barrier arranged along the cell stack axis, wherein the at least one thermal barrier has a plurality of more compressible parts attached to a plurality of less compressible parts to form at least one channel configured to pass a liquid coolant through the cell stack.

[0004] In some aspects, the techniques described herein relate to an assembly in which at least one channel opens to a first side of the cell stack and to an opposite second side of the cell stack.

[0005] In some aspects, the techniques described herein relate to an assembly in which at least one channel has a rectangular cross-section.

[0006] In some aspects, the techniques described herein relate to an assembly, where the first side is a first horizontal side and the second side is a second horizontal side.

[0007] In some aspects, the techniques described herein relate to an assembly in which the at least one channel is arranged between axially adjacent battery cells within the plurality of battery cells.

[0008] In some aspects, the techniques described herein relate to an assembly in which at least one thermal barrier is compressible.

[0009] In some aspects, the techniques described herein relate to an assembly, where the multitude of more compressible parts is a multitude of foam parts.

[0010] In some aspects, the techniques described herein relate to an assembly, where the multitude of less compressible parts is a multitude of metal parts.

[0011] In some aspects, the techniques described herein relate to an assembly, where the multitude of metal parts is a multitude of aluminum parts.

[0012] In some aspects, the techniques described herein relate to an assembly in which the plurality of less compressible parts provides at least two sides of a liquid coolant channel through the cell stack and the plurality of more compressible parts provides at least two other sides of the liquid coolant channel.

[0013] In some aspects, the techniques described herein relate to an assembly, wherein the multitude of less compressible parts provide opposite horizontal sides of the liquid coolant channel, and wherein the multitude of more compressible parts provide opposite vertical sides of the liquid coolant channel.

[0014] In some aspects, the techniques described herein relate to an assembly in which each of the multitude of more compressible parts includes sections that are inserted between two of the less compressible parts within the multitude of less compressible parts.

[0015] In some aspects, the techniques described herein relate to an assembly in which the multitude of more compressible parts are attached to the multitude of less compressible parts using an adhesive.

[0016] In some aspects, the techniques described herein relate to an assembly, where the multitude of more compressible parts is a multitude of foam strips and the multitude of less compressible parts is a multitude of metal strips.

[0017] In some aspects, the techniques described herein relate to an assembly, where the cell stack is one of a multitude of cell stacks within the interior.

[0018] In some aspects, the techniques described herein relate to an assembly, where the liquid coolant is a dielectric liquid coolant.

[0019] In some aspects, the techniques described herein relate to a traction battery pack assembly comprising: at least one first battery cell of a cell stack; at least one second battery cell of the cell stack; and a thermal barrier assembly of the cell stack, wherein the thermal barrier assembly is arranged axially between the at least one first battery cell and the at least one second battery cell, wherein the thermal barrier assembly comprises a plurality of foam parts inserted between a plurality of first metal parts and a plurality of second metal parts, and wherein the thermal barrier assembly is configured to guide a liquid coolant through the cell stack between the at least one first battery cell and the at least one second battery cell.

[0020] In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein the thermal barrier assembly forms at least one liquid coolant channel.

[0021] In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein the multitude of foam parts and the multitude of metal parts form the at least one liquid coolant channel.

[0022] In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein each of the multiple metal parts is glued to two of the multiple foam parts.

[0023] The embodiments, examples, and alternatives described in the preceding paragraphs, the claims, or the following description and drawings, which may include any of their various aspects or individual features, can be considered independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, provided such features are not incompatible. BRIEF DESCRIPTION OF THE FIGURES

[0024] The various features and advantages of the disclosed examples will be apparent to the person skilled in the art from the detailed description. The figures accompanying the detailed description can be briefly described as follows: Fig. Figure 1 illustrates a side view of an electrified vehicle that has a battery pack. Fig. Figure 2 illustrates a perspective, schematic view of the battery pack of the Fig. 1. Fig. Figure 3 illustrates a side view of a section of the battery pack. Fig. 2, showing a section of a cell stack positioned between an envelope cover and an envelope shell. Fig. Figure 4 illustrates a perspective view of a thermal barrier made from the cell stack of the Fig. 3. Fig. Figure 5 illustrates an end view of the thermal barrier of the Fig. 4. Fig. Figure 6 illustrates an enlarged view of the thermal barrier of the Fig. 4. DETAILED DESCRIPTION

[0025] An immersion heat control system can be used to regulate thermal energy in a traction battery pack. In such a traction battery pack, at least some components are immersed in a liquid coolant. The immersed components may include a cell stack.

[0026] This disclosure relates to guiding the liquid coolant through the cell stack using channels provided by a compressible barrier. During operation, cells may swell. Because the thermal barrier is compressible, it can accommodate this swelling.

[0027] With reference to Fig. Figure 1 includes an electrified vehicle 10 comprising a traction battery pack 14, an electric motor 18, and wheels 22. The traction battery pack 14 supplies power to an electric motor 18, which can convert electrical power into mechanical power to drive the wheels 22. The traction battery pack 14 can be a battery with a relatively high voltage.

[0028] In the exemplary embodiment, the traction battery pack 14 is secured to an underbody 26 of the electrified vehicle 10. In other examples, the traction battery pack 14 could be located elsewhere on the electrified vehicle 10.

[0029] The electrified vehicle 10 is a fully electric vehicle. In other examples, the electrified vehicle 10 is a hybrid electric vehicle that selectively drives wheels using torque provided by an internal combustion engine instead of, or in addition to, an electric motor. Generally, the electrified vehicle 10 could be any type of vehicle that incorporates a traction battery pack.

[0030] Although the different examples feature the specific components shown in the illustrations, embodiments of this disclosure are not limited to these specific combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another of the examples. Furthermore, the various figures accompanying this disclosure are not necessarily to scale, and some features may be enlarged or reduced to show certain details of a specific component or arrangement.

[0031] Fig. 2 and Fig. Figure 3 illustrates additional details of the exemplary battery pack 14. In this example, the battery pack 14 includes an enclosure assembly 30. The enclosure assembly 30 includes a cover 34 and a shell 38. In this example, the cover 34 is located vertically above the shell 38. However, in other examples, the cover 34 could be located below or on one side of the shell 38.

[0032] Various terms, such as "vertical", "above", "below", "top" and "bottom", are used in the different drawings to refer to the arrangement of the components of the battery pack 14 and should not otherwise be considered restrictive. These terms refer to the general orientation of the battery pack 14 when it is installed within the vehicle 10. Fig. 1 is built in.

[0033] In one example of this disclosure, the cover 34 is welded to the shell 38. While welding is mentioned, the cover 34 and the shell 38 could be joined using other fluid-tight joining techniques, such as adhesives. Furthermore, while an exemplary enclosing assembly 30 is shown in the drawings, the enclosing assembly 30 can vary in size, shape, and configuration within the scope of this disclosure.

[0034] In this disclosure, a cell stack 42 is arranged within an interior space of the enclosing assembly 30. The exemplary cell stack 42 comprises a plurality of individual battery cells 46 arranged along a cell stack axis A, and a plurality of thermal barriers 50. Each of the thermal barriers 50 can be inserted along the cell stack axis between two of the battery cells 46.

[0035] The cell stack 42 could contain any number of battery cells 46. The battery pack 14 could incorporate any number of cell stacks 42 within the casing assembly 30. Thus, this disclosure is not limited to the Fig. The exact configuration shown is limited to 2. While the battery cells 46 and the thermal break devices 50 of the Fig. 3 are positioned next to each other relative to each other, other configurations within the scope of this disclosure are also considered, including, among others, embodiments in which the battery cells 46 and the thermal barriers 50 are stacked on top of each other, for example.

[0036] In one embodiment, the battery cells are 46 prismatic lithium-ion cells. However, within the scope of this disclosure, alternatively battery cells could be used that have other geometries (cylindrical, pouch, etc.), other chemical compositions (nickel-metal hydride, lead-acid, etc.), or both.

[0037] The cell stack 42 is arranged in the interior of the encapsulation assembly 30 between the shell 38 and the cover 34. A thermal control system is used to regulate thermal energy levels within the battery pack 14. The exemplary thermal control system is configured to circulate a non-conductive (i.e., a dielectric) coolant C over areas of the cell stack 42 to regulate thermal energy within the cell stack 42, for example, by using the coolant C to absorb heat from the cell stack 42. The thermal control system is an immersion thermal control system because at least sections of the battery pack 14, here at least the battery cells 46 of the cell stack 42, are immersed in the coolant C.

[0038] In this example, the coolant C generally flows from an inlet 54 formed in the cover 34 to an outlet 58 formed in the basin 38 at an end of the casing assembly 30 opposite the inlet 54.

[0039] The cell stack 42 has a top surface 62, opposing outer sides 64, and a bottom surface 66. Within the interior of the casing assembly 30, a portion of the coolant C is guided between the battery cells 46 through the cell stack 42 via at least one channel 70 formed by the thermal barriers 50. Thermal energy can be transferred between the coolant and the battery cells 46 as the coolant C moves between the battery cells 46 through the at least one channel 70.

[0040] With reference to the Fig. 4-6 and with further reference to the Fig. 2 and Fig.3 The exemplary thermal barriers 50 include a variety of more highly compressible parts 78 and a variety of less compressible parts 82. The thermal barriers 50 can each be positioned between axially adjacent cells 46 of the cell stack 42.

[0041] The more compressible parts 78 are vertically offset from the less compressible parts 82. In this example, the more compressible parts 78 overlap the less compressible parts 82 vertically by approximately 2 millimeters. Each of the less compressible parts 82 is attached to two of the more compressible parts 78. The more compressible parts 78 are inserted between less compressible parts 82 on a first axial side and less compressible parts 82 on an opposite second axial side.

[0042] The more compressible parts 78 can be made of foam, such as polymer-based foam. The less compressible parts 82 can be made of metallic material, such as aluminum. Both the more compressible parts 78 and the less compressible parts 82 are strips and, in this example, have rectangular cross-sections. The more compressible parts 78 are 10 millimeters high and 3 millimeters wide in this example, and the less compressible parts 82 are 8 millimeters high and 1.5 millimeters wide.

[0043] The uppermost, more compressible part 78 contacts a bottom surface of the casing cover 34 and is glued to two of the less compressible parts 82. The lowermost, more compressible part 78 contacts a base of the casing shell 38 and is glued to two of the less compressible parts 82. The remaining more compressible parts 78 are glued to four of the less compressible parts 82. Adhesive can be used to bond the less compressible parts 82 and the more compressible parts 78 together. When installed inside the battery pack 14, the cell stack 42 can be compressed along the cell stack axis A, causing the more compressible parts 78 to be slightly compressed at their corners. In this example, the more compressible parts 78 are compressed by 0.5 millimeters by each of the less compressible parts 82.

[0044] At the top and bottom of the cell stack 42, the contact between the thermal barrier 50 and the encapsulation assembly 30 can help to disperse venting byproducts within areas of the interior of the battery pack 14, for example, during a thermal event in which one or more of the battery cells 46 vent. The venting byproducts are vented from the battery cells 46 into the liquid coolant and then guided laterally outwards instead of along the cell stack axis A.

[0045] In this example, the thermal barriers 50 each include four of the more compressible parts 78, which are inserted between three of the less compressible parts on a first axial side and three of the less compressible parts on an opposite, second axial side.

[0046] The at least one channel 70 of the exemplary thermal barriers 50 includes three channels 86, which have a circumferential edge that is completely formed by the thermal barrier 50. The channels 86 open to the opposite outer sides of the cell stack 42 and to the second side of the cell stack 42. The channels 86 extend through the cell stack 42. The liquid coolant introduced through the inlet 54 can be guided through the channels 86 and thus through the cell stack 42.

[0047] In another example, one or more of the thermal barriers 50 could be rotated around the cell stack axis A with the cell stack 42, so that the channels 70 extend vertically rather than horizontally.

[0048] The exemplary channels 86 have a rectangular cross-section. The more compressible parts 78 form the top and bottom surfaces of the channels 86. The less compressible parts 82 form opposite horizontal surfaces of the channels 86. A different number of more compressible parts 78 and less compressible parts 82 could be used to form more than three channels 86 or fewer than three channels 86.

[0049] The liquid coolant can also be guided through channels 90 through the cell stack 42, which have edges formed on the top and bottom by the less compressible parts 82, on one horizontal side by one of the more compressible parts 78 and on the other horizontal side by one of the battery cells 46.

[0050] Features of disclosed examples include a thermal barrier that provides space for a flow of coolant between cells and guides a flow moving between cells. The thermal barrier can be provided by a variety of strips—some more compressible than others. The use of strips can facilitate fabrication. Material webs, such as mica material webs, may not be necessary.

[0051] The preceding description is exemplary and not limiting. A person skilled in the art may deduce variations and modifications of the disclosed examples that do not necessarily deviate from the core of this disclosure. Therefore, the scope of protection granted by this disclosure can only be determined by reading the following patent claims.

Claims

[1] Traction battery pack assembly comprising: a cell stack within an interior of an enclosure, wherein the cell stack comprises a plurality of battery cells arranged along a cell stack axis and at least one thermal barrier arranged along the cell stack axis, wherein the at least one thermal barrier has a plurality of more compressible parts attached to a plurality of less compressible parts to form at least one channel configured to direct a liquid coolant through the cell stack. [2] Assembly according to claim 1, wherein the at least one channel opens to a first side of the cell stack and to an opposite second side of the cell stack and wherein the at least one channel optionally has a rectangular cross-section. [3] Assembly according to claim 2, wherein the first side is a first horizontal side and the second side is a second horizontal side. [4] Assembly according to claim 2, wherein the at least one channel between axially adjacent battery cells is arranged within the plurality of battery cells. [5] Assembly according to claim 1, wherein the at least one thermal barrier is compressible and wherein optionally the plurality of more compressible parts is a plurality of foam parts. [6] Assembly according to claim 5, wherein the plurality of less compressible parts is a plurality of metal parts and wherein optionally the plurality of metal parts is a plurality of aluminium parts. [7] Assembly according to claim 1, wherein the plurality of less compressible parts provides at least two sides of a liquid coolant channel through the cell stack and the plurality of more compressible parts provides at least two other sides of the liquid coolant channel and wherein optionally the plurality of less compressible parts provides opposite horizontal sides of the liquid coolant channel, wherein the plurality of more compressible parts provides opposite vertical sides of the liquid coolant channel. [8] Assembly according to claim 7, wherein each of the plurality of more compressible parts includes sections that are inserted between two of the less compressible parts within the plurality of less compressible parts. [9] Assembly according to claim 7, wherein the plurality of more compressible parts is attached to the plurality of less compressible parts using an adhesive. [10] Assembly according to claim 7, wherein the plurality of more compressible parts is a plurality of foam strips and the plurality of less compressible parts is a plurality of metal strips. [11] Assembly according to claim 1, wherein the cell stack is one of a plurality of cell stacks within the interior. [12] Assembly according to claim 1, wherein the liquid coolant is a dielectric liquid coolant. [13] Traction battery pack assembly comprising: at least one first battery cell of a cell stack; at least one second battery cell of a cell stack; and a thermal barrier assembly of the cell stack, wherein the thermal barrier assembly is arranged axially between the at least one first battery cell and the at least one second battery cell, wherein the thermal barrier assembly includes a plurality of foam parts inserted between a plurality of first metal parts and a plurality of second metal parts, wherein the thermal barrier assembly is configured to guide a liquid coolant through the cell stack between the at least one first battery cell and the at least one second battery cell. [14] Traction battery pack assembly according to claim 13, wherein the heat barrier assembly forms at least one liquid coolant channel and wherein optionally the plurality of foam parts and the plurality of metal parts form the at least one liquid coolant channel. [15] Traction battery pack assembly according to claim 13, wherein each of the plurality of metal parts is glued to two of the foam parts of the plurality of foam parts.

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