CN117691288A

CN117691288A - Traction battery pack separator and ventilation path establishment method

Info

Publication number: CN117691288A
Application number: CN202311106893.3A
Authority: CN
Inventors: 穆罕默德雷萨·埃夫特哈里; 丹尼尔·本杰明·科克; 帕特里克·丹尼尔·马圭尔; 布罗克·邓拉普; 迈克尔·E·雷布林
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2022-09-02
Filing date: 2023-08-30
Publication date: 2024-03-12

Abstract

The present disclosure provides a "traction battery pack separator and ventilation path establishment method". A traction battery pack assembly comprising: a battery pack housing providing an interior region; and at least one cell stack comprising a battery cell and at least one separator distributed along a cell stack axis. The at least one divider divides the interior region into a plurality of compartments. Each of the compartments accommodates at least one of the battery cells.

Description

Traction battery pack separator and ventilation path establishment method

Cross Reference to Related Applications

The present application claims priority from U.S. provisional application No. 63/403445, filed on month 9 and 2 of 2022, which is incorporated herein by reference.

Technical Field

The present disclosure relates generally to dividing the area of a traction battery pack to facilitate ventilation of battery cells of the traction battery pack.

Background

The traction battery pack of an motorized vehicle may include a battery cell stack arranged in one or more cell stacks. Sometimes, the pressure and thermal energy in one or more of the battery cells may increase. In response, gases and debris may be released from those battery cells.

Disclosure of Invention

In some aspects, the technology described herein relates to a traction battery pack assembly comprising: a battery pack housing providing an interior region; and at least one cell stack comprising a plurality of battery cells and at least one divider distributed along a cell stack axis, the at least one divider dividing the interior region into a plurality of compartments, each of the compartments holding at least one of the battery cells.

In some aspects, the technology described herein relates to an assembly wherein the at least one divider is biased against the battery pack housing.

In some aspects, the technology described herein relates to an assembly wherein the at least one divider is biased against a housing cover of the battery pack housing.

In some aspects, the technology described herein relates to an assembly wherein the at least one separator is adhered to the battery pack housing, the beam of the battery pack housing, or both.

In some aspects, the technology described herein relates to an assembly wherein the at least one divider is at least one metal or metal alloy divider.

In some aspects, the technology described herein relates to an assembly wherein the at least one divider includes a tab portion that protrudes outward from the cell stack axis beyond the plurality of battery cells.

In some aspects, the technology described herein relates to an assembly wherein the tab portion includes a first section that curves toward an axial end of the cell stack and a second section that curves away from the axial end of the cell stack.

In some aspects, the technology described herein relates to an assembly wherein the tab portion protrudes vertically upward beyond the plurality of battery cells.

In some aspects, the technology described herein relates to an assembly wherein the at least one separator is sandwiched between a plurality of porous separators along the cell stack axis.

In some aspects, the technology described herein relates to an assembly wherein the porous spacer is foam.

In some aspects, the technology described herein relates to an assembly wherein the porous spacer is an aerogel.

In some aspects, the technology described herein relates to an assembly wherein the plurality of compartments are fluidly isolated from each other.

In some aspects, the technology described herein relates to an assembly wherein the at least one cell stack includes a first cell stack and a second cell stack, and further comprising a beam assembly disposed between the first cell stack and the second cell stack.

In some aspects, the technology described herein relates to an assembly wherein a plurality of compartments are configured to vent through at least one opening in the beam assembly to an interior of the beam assembly.

In some aspects, the technology described herein relates to a method of establishing a ventilation path within a battery pack, the method comprising: within a battery pack housing, an interior region of the battery pack housing is divided into a plurality of compartments using at least one partition of a cell stack, each of the compartments housing at least one battery cell of the cell stack.

In some aspects, the technology described herein relates to a method comprising biasing the at least one divider against a portion of the battery pack housing.

In some aspects, the technology described herein relates to a method wherein the portion of the battery pack housing is a housing cover.

In some aspects, the technology described herein relates to a method comprising buckling the at least one separator when the at least one separator is biased against the portion of the battery pack housing.

In some aspects, the techniques described herein relate to a method wherein the buckling is buckling of a tab portion of the at least one separator that protrudes outward from the cell stack axis beyond the at least one cell of the cell stack, the tab portion including a first section that curves toward an axial end of the cell stack and a second section that curves away from the axial end of the cell stack.

In some aspects, the technology described herein relates to a method further comprising venting gas from at least one battery cell of a given one of the compartments to an interior of a beam assembly located in the interior region.

Embodiments, examples, and alternatives of the foregoing paragraphs, claims, or the following description and drawings, including any of their various aspects or respective individual features, may be employed separately or in any combination. Features described in connection with one embodiment are applicable to all embodiments unless such features are incompatible.

Drawings

Various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The drawings that accompany the detailed description can be briefly described as follows:

FIG. 1 illustrates a side view of an example motorized vehicle.

Fig. 2 shows an exploded perspective view of a battery pack from the motorized vehicle of fig. 1, and schematically illustrates a cell stack of the battery pack.

Fig. 3 shows a cross-sectional view taken at line 3-3 in fig. 2.

Fig. 3A shows a close-up of the area of fig. 3.

Fig. 4 shows a perspective view of a portion of a cell stack from the battery pack of fig. 2 alongside a portion of a beam assembly from the battery pack of fig. 2.

FIG. 5 shows a schematic top view of the venting of gas and debris from the compartment into the beam assembly shown in FIG. 4.

Detailed Description

The present disclosure details exemplary methods and systems for dividing an interior region of a traction battery pack. The partitioning may help contain and direct gases and debris that are vented from one or more battery cells during a thermal event. Directing the vented gases and debris away from other battery cells (other battery cells that are not vented) may help prevent thermal events from cascading to those other battery cells.

Referring to fig. 1, an motorized vehicle 10 includes a battery pack 14, a motor 18, and wheels 22. The battery pack 14 powers an electric motor 18 that may convert electrical power to mechanical power to drive wheels 22.

In the exemplary embodiment, battery pack 14 is secured to underbody 26 of electric vehicle 10. In other examples, the battery pack 14 may be located elsewhere on the motorized vehicle 10.

The motorized vehicle 10 is a pure electric vehicle. In other examples, the motorized vehicle 10 is a hybrid electric vehicle that selectively uses torque provided by an internal combustion engine (as an alternative or in addition to an electric motor) to drive wheels. In general, the motorized vehicle 10 may be any type of vehicle having a battery pack.

Referring now to fig. 2-5, the battery pack 14 includes a plurality of battery cells 30 held within a battery pack housing 34. In the exemplary embodiment, housing 34 includes a housing cover 38 and a housing tray 42. The housing cover 38 is secured to the housing tray 42 to provide an interior region 44 that accommodates the cell stack 30. The housing cover 38 may be secured to the housing tray 42 using, for example, mechanical fasteners (not shown).

Each of the cell stacks 30 includes a plurality of battery cells 50 (or simply "cells") and at least one divider 54 distributed along a respective cell stack axis a. The cell stacks 30 each extend from a first axial end 56A to an opposite second axial end 56B.

Within each cell stack 30, the battery cells 50 are stacked side-by-side with respect to one another along a cell stack axis a. The battery cell 50 stores and supplies electric power. Although a particular number of cell stacks 30 and cells 50 are shown in the various figures of the present disclosure, the battery pack 14 may include any number of cell stacks 30 having any number of individual cells 50.

In one embodiment, the battery cell 50 is a lithium ion pouch cell. However, battery cells having other geometries (cylindrical, prismatic, etc.), other chemistries (nickel-metal hydride, lead acid, etc.), or both, may alternatively be used within the scope of the present disclosure.

The example battery cell 50 may include tab terminals extending from the housing. For example, an aluminum film may provide the housing.

Sometimes, the pressure and thermal energy in one or more of the battery cells 50 may increase. For example, the pressure and thermal energy increases may be due to an overcharge condition. The pressure and thermal energy increases may cause the associated battery cells 50 to rupture and release gases and debris.

The gas and debris may be released from the associated battery cells 50 through designated vents in the housing (such as a diaphragm that yields in response to an increase in pressure) or through the ruptured area of the associated battery cells 50. If a designated vent, the vent may be positioned to direct the flow of vented gases and debris away from the terminals of the battery cells 50.

In these examples, the battery pack 14 includes a beam assembly 66 disposed between the cell stacks 30. The exemplary beam assembly 66 extends longitudinally in a direction parallel to the cell stack axis a. The beam assembly 66 and the cell stack axis a extend in the vehicle transverse direction (i.e., from the driver side to the passenger side).

In this example, the beam assembly 66 includes two beams 70 sandwiching a barrier 74. In this example, the two beams 70 have a "C" shaped cross-section and are positioned to provide a first channel 78A within the beam assembly 66 on a first side of the barrier 74 and another second channel 78B within the beam assembly 66 on an opposite second side of the barrier 74.

The beam assembly 66 includes a plurality of openings 82 in each of the beams 70. Gases and debris vented from the interior of the battery cell 50 may move through at least one of the openings 82 into the passage 78A or 78B within the beam assembly 66. The gas and debris are transferred through the passage 78A or 78B to an area outside of the battery pack 14.

To help direct gas through the openings 82 of the beam assembly 66, the dividers 54 protrude outwardly from the stack axis a beyond the plurality of battery cells 50. In this example, the separator 54 protrudes outwardly far enough to contact the battery pack housing 34. In some examples, the area of the battery pack housing 34 contacted by the separator 54 is lined with organic paper.

Extending the divider 54 to the housing 34 and the beam 70 divides the interior region 44 into a plurality of compartments 86.

The divider 54 may be bonded to the housing 34 and the beam 70 to seal the compartment 86. The adhesive may be an epoxy-based, silicone-based or acrylic-based adhesive with a heat-resistant additive. The adhesion of the separator 54 to the housing 34 and the beam 70 helps to improve the torsional rigidity and bending rigidity of the battery pack. Each of these compartments 86 holds at least one of the battery cells 50 of a given one of the cell stacks 30. In this example, three of the compartments 86 each hold four of the battery cells 50 of a given cell stack 30, and two of the compartments 86 hold two of the battery cells 50 of a given cell stack 30. Each of the compartments 86 is fluidly isolated from the other compartments 86. The beam assembly 66 and the housing 34 establish other boundaries of the compartment 86.

Gases and debris exhausted from one or more of the battery cells 50 in a given one of the compartments 86 are directed through one of the openings 82 into the passage 78A of the beam assembly 66, rather than flowing through the battery cells 50 outside the given one of the compartments 86. The flow of gas through the battery cells 50 may cause thermal events to occur in those battery cells 50 in the other compartments 86.

For example, the openings 82 in the beams 70 may each be covered by a diaphragm. The membrane ruptures to allow gas to flow from one of the compartments 86 into the channel 78A or 78B. The diaphragm prevents the vented gases from flowing back from the passage 78A or 78B through one of the openings 82 to one of the compartments 86 of the battery cell 50 that remains unventilated.

In this example, the dividers 54 each include a tab portion 90 that protrudes outward from the cell stack axis a beyond the plurality of battery cells 50. The exemplary tab portion 90 protrudes vertically upward beyond the plurality of battery cells 50 and contacts the housing cover 38. For purposes of this disclosure, vertical is the general orientation of the reference ground and the motorized vehicle 10 during operation.

The example tab portion 90 includes a first section 92 that curves toward the axial end 56A of the cell stack 30 and a second section 94 that curves away from the axial end 56A of the cell stack 30. Biasing may be facilitated using both the first section 92 and the second section 94. In another example, the tab portion 90 includes only the first section 92, but the first section 92 extends such that the first section 92 may contact the housing cover 38.

When the housing cover 38 is secured to the housing tray 42, the housing cover 38 is pulled closer to the housing tray 42 and pressed down against the tab portion 90. This flexes the exemplary tab portion 90 in direction D (fig. 3A).

The exemplary divider 54 is a metal or metal alloy, such as aluminum. In this example, the divider 54 has a nominal thickness of one millimeter. In another example, the divider 54 may be a polymer-based material or another type of non-metallic material.

When the housing cover 38 is secured to the housing tray 42, the tab portion 90 is biased against the housing cover 38. The bias helps to seal the compartments 86 from each other. Although biased against the housing cover 38 in this example, the divider 54 may alternatively be biased against another portion of the housing 34. In some examples, the divider 54 may alternatively or additionally be adhered to the housing cover 38 or the housing tray 42.

In the exemplary embodiment, each of the cell stacks 30 includes a plurality of spacers 98. The spacers 54 are each sandwiched between a pair of spacers 98. Exemplary spacers 98 are porous spacers, which are foam or aerogel. The spacers 98 may help inhibit heat energy transfer from one compartment 86 to another. If desired, the spacer 98 may be an insulating material to reduce heat transfer from the cell stack 30 being vented to an adjacent cell stack 30 that is not yet vented. The spacer 98 may also act as a compliant layer to first allow some lower limit on cell swelling and expansion, then compress to provide a higher limit on cell swelling and expansion as the cell tries to swell more over time and use. The spacer 98 may also act as a compliant barrier to further seal between the cell stacks 30, wherein the second section 94 is not fully or securely closed against the housing 34.

In these examples, the dividing is accomplished using the tab portion 90 of the divider 54. In another example, a separate structure from the partition 54 may be used. For example, foam tapes may be positioned between the housing 34 and the cell stack 30 to divide the interior region 44. The foam tapes are distributed along the axis of the cell stack even though the foam tapes may not extend between any of the cells of the cell stack.

Thus, a method of establishing a ventilation path for one or more of the battery cells 50 includes using at least one of the dividers 54 of the cell stack 30 to divide the interior region 44 of the battery pack housing 34 into compartments 86. Each of the compartments 86 houses one or more of the battery cells 50. The method may include biasing the divider 54 against a portion of the battery pack housing 34, here the housing cover 38.

The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Accordingly, the scope of protection afforded the present disclosure can only be determined by studying the following claims.

Claims

1. A traction battery pack assembly, comprising:

a battery pack housing providing an interior region; and

at least one cell stack comprising a plurality of battery cells and at least one divider distributed along a cell stack axis, the at least one divider dividing the interior region into a plurality of compartments, each of the compartments holding at least one of the battery cells.

2. The assembly of claim 1, wherein the at least one divider is biased against the battery pack housing, and optionally wherein the at least one divider is biased against a housing cover of the battery pack housing.

3. The assembly of claim 1, wherein the at least one divider is adhered to the battery pack housing, a beam of the battery pack housing, or both.

4. The assembly of claim 1, wherein the at least one divider is at least one metal or metal alloy divider.

5. The assembly of claim 1, wherein the at least one divider comprises a tab portion that protrudes outwardly from the cell stack axis beyond the plurality of battery cells, and optionally wherein the tab portion protrudes vertically upward beyond the plurality of battery cells.

6. The assembly of claim 5, wherein the tab portion comprises a first section that curves toward an axial end of the cell stack and a second section that curves away from the axial end of the cell stack.

7. The assembly of claim 1, wherein the at least one spacer is sandwiched between a plurality of porous spacers along the cell stack axis, and optionally wherein the porous spacers are foam or aerogel.

8. The assembly of claim 1, wherein the plurality of compartments are fluidly isolated from each other.

9. The assembly of claim 1, wherein the at least one cell stack comprises a first cell stack and a second cell stack, and further comprising a beam assembly disposed between the first cell stack and the second cell stack, and optionally wherein a plurality of compartments are configured to vent through at least one opening in the beam assembly to an interior of the beam assembly.

10. A method of establishing a vent path within a battery pack, comprising:

within a battery pack housing, an interior region of the battery pack housing is divided into a plurality of compartments, each containing at least one battery cell of the battery stack, using at least one divider of the battery cell stack.

11. The method of claim 10, further comprising biasing the at least one divider against a portion of the battery pack housing.

12. The method of claim 11, wherein the portion of the battery pack housing is a housing cover.

13. The method of claim 11, further comprising buckling the at least one spacer when biasing the at least one spacer against the portion of the battery pack housing.

14. The method of claim 13, wherein the buckling is buckling of a tab portion of the at least one divider that protrudes outward from a cell stack axis beyond the at least one cell of the cell stack, the tab portion comprising a first section that curves toward an axial end of the cell stack and a second section that curves away from the axial end of the cell stack.

15. The method of claim 10, further comprising venting gas from at least one battery cell of a given one of the compartments to an interior of a beam assembly located in the interior region.