Battery module with inwardly deformed cover

Abstract

A battery module includes a container, a plurality of battery cells within the container, and a cover attached to a side of the container and extending in a plane above the plurality of battery cells, where the cover includes an inner layer and an outer layer. When a thermal event occurs in one battery cell, the battery cover may deflect inwardly toward the battery cell.

Description

Technical Field

[0001] The present invention relates to a battery module, in particular to a battery module for a vehicle. Background Art

[0002] Rechargeable battery cells can be used in a variety of modern technology applications, such as electronic devices, electric bicycles, hybrid vehicles, electric vehicles, etc. In certain applications, the battery cells are contained in one or more battery modules including a plurality of battery cells. Therefore, a "battery module" as used herein refers to a plurality of battery cells connected in series and / or in parallel and housed in a mechanical structure. Optionally, the battery module may further include thermal management features, such as a cold plate, sensors for voltage, temperature or pressure, etc. The battery module may include a cover to protect the module. Battery cells sometimes experience adverse thermal runaway, in which the heat generated by a source (such as a battery cell) is greater than the ability of the module to dissipate heat to its surroundings. For example, thermal runaway occurs when a battery is short-circuited or damaged. This can result in an adverse temperature increase in the battery module and an undesirable deformation of the module cover. In particular, the battery cover can experience thermal expansion, which, when combined with ejected material from a damaged battery cell, can cause the cover to bend outward from the module. For example, as Figure 1 As shown, when a thermal event occurs in a prior art module having a single-layer cover 20 secured at point 24, the cover 20 bends outwardly from the battery cells 41 and thermal barriers 42. This outward deformation increases gaps 60 and 61 and can expose adjacent battery cells 41 to heat, including ejected hot particulate matter that can propagate thermal runaway. Summary of the invention

[0003] In one exemplary embodiment, a battery module is disclosed that includes a container, a plurality of battery cells within the container, and a cover attached to a side of the container and extending in a plane above the plurality of battery cells, wherein the cover includes an inner layer and an outer layer.

[0004] Additionally, the battery module may include one or more of the following features.

[0005] The battery module may include a thermal barrier separating a first group of the plurality of battery cells from a second group of the plurality of battery cells. The battery module may include a gap between the cover and top edges of the plurality of battery cells, and the thermal barrier extends upwardly toward the cover into the gap.

[0006] When a thermal event occurs in one or more of the plurality of battery cells in the battery module, the cover deforms inwardly toward the plurality of battery cells.

[0007] The inner layer of the battery module can be attached to the outer layer at at least two fixed locations. At least two fixed locations can be at two opposite edges of the cover. In addition, the fixed locations at the opposite edges of the inner layer can be attached to the outer layer at one or more additional locations within the perimeter of the cover. The attachments at the one or more additional locations within the perimeter of the cover can be welds. The inner layer can be attached to the outer layer by a laminate material located between the inner layer and the outer layer. The laminate material can include an adhesive material, an insulating material, or both. The inner layer can be attached to the outer layer by roll bonding.

[0008] The inner layer and the outer layer are formed of the same material, or the inner layer can be a first material and the outer layer can be a second material. Both the first material and the second material can be metals. The metal can be independently selected for each of the inner layer and the outer layer from carbon steel, alloy steel, copper, aluminum and zinc.

[0009] The thermal expansion coefficient of the inner layer may be greater than the thermal expansion coefficient of the outer layer.

[0010] The thickness of the cover may be 0.4 to 5 mm. The thickness of the inner layer may be 0.2 to 2.5 mm, and the thickness of the outer layer may be 0.1 to 2.5 mm. The thickness of the inner layer may be greater than the thickness of the outer layer.

[0011] The cell cover may include one or more vents to allow gases to exit the module.

[0012] In another exemplary embodiment, a battery module is disclosed, comprising a container, a plurality of battery cells within the container, a thermal barrier separating a first group of the plurality of battery cells from a second group of the plurality of battery cells, and a cover attached to a side of the container and extending in a plane above the plurality of battery cells, wherein the cover comprises an inner layer and an outer layer, wherein the inner layer is attached to the outer layer at at least two fixed locations, wherein a gap exists between the cover and a top edge of the plurality of battery cells and the thermal barrier extends upward toward the cover into the gap, wherein when a thermal event occurs within one or more of the plurality of battery cells, the cover deforms inwardly toward the plurality of battery cells, and wherein the battery cover comprises one or more vents to enable gases to vent out of the module.

[0013] The above features and advantages and other features and advantages of the present disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Other features, advantages and details appear, by way of example only, in the following detailed description, which refers to the accompanying drawings, in which:

[0015] Figure 1 is a schematic cross-sectional view of a prior art module cover of a module experiencing a thermal event;

[0016] Figure 2is a perspective view of a schematic diagram of a battery module;

[0017] Figure 3 It passes through Figure 2 A schematic partial cross-sectional view of a battery module taken along line AA';

[0018] Figure 4 It passes through Figure 2 A schematic partial cross-sectional view of a battery module experiencing a thermal event along line AA';

[0019] Figure 5 A in FIG. 1 is a cross-sectional schematic diagram of an example of a module cover disclosed herein; and

[0020] Figure 5 B to D in FIG. 1 are cross-sectional schematic diagrams of examples of a module cover as disclosed herein undergoing a thermal event. DETAILED DESCRIPTION

[0021] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate the same or corresponding parts and features.

[0022] According to an exemplary embodiment, Figure 2 As shown, the battery module 10 includes a container 30 and a cover 20. The cover may include optional vents 22. Figure 3 As shown, there are multiple groups 40 of battery cells 41 within the container 30, wherein each group 40 is separated from an adjacent group 40 by a thermal barrier 42. The thermal barrier extends beyond the top edge 45 of the battery cells 41 into a gap 60. The cover 20 is located above the battery cells 41 and the thermal barrier 42, with a small gap 61 between the top of the thermal barrier 42 and the cover 20. The cover 20 may optionally include one or more vents 22. The vents 22 may optionally include a vent cover 23 that is broken or removed due to a thermal event occurring under the vent cover 23. For example, the vent cover 23 may include a thin sheet of flexible material, such as mica. The cover 20 includes an outer layer 25 and an inner layer 26.

[0023] like Figure 4 As shown, in the event of a thermal event in one of the battery cell groups 41 43 , the double-layer structure of the cover 20 causes the cover to deform inwardly. This inward deformation can shrink or close the gap 61 above the thermal barrier 42, thereby inhibiting the thermal event from propagating to other battery cell groups 40.

[0024] The inward deformation may be the result of the inner layer 26 being closer to the thermal event than the outer layer 25, and therefore heating and expanding faster than the outer layer 25, causing the inward deformation. Additionally or alternatively, the inner layer 26 may have a higher coefficient of thermal expansion than the outer layer 25, causing the inner layer to expand more or more rapidly, thereby causing the inward deformation.

[0025] As an example of a structure, Figure 5 A in FIG. 1 shows a cover 20 having an inner layer 26 and an outer layer 25 physically connected at two or more fixed locations 24. The connection of the inner layer 26 and the outer layer 25 at the fixed locations 24 is required to cause the cover 20 to deform inwardly when the inner layer 26 expands during a thermal event.

[0026] like Figure 5 As shown in FIG. 1B , the inner layer 26 and the outer layer 25 may be physically connected over a continuous portion of the cover 20. The continuous portion may be the entire cover 20. Figure 5 As shown in C and D in FIG. 2 , the inner layer 26 and the outer layer 25 can be physically connected at separate isolated connection locations 27 spaced apart on the cover 20. These separate connection locations can be, for example, welds (eg, spot welds or weld lines).

[0027] The physical connection of the inner layer 26 and the outer layer 25 can be achieved by a bonding method such as roll bonding, coating (e.g., zinc coating), mechanical attachment (e.g., welding), or lamination using an intermediate material between the inner layer 26 and the outer layer 25, or a combination thereof. The intermediate material can be, for example, an adhesive or an insulating material. The intermediate material can be sacrificial so that it decomposes when a thermal event occurs. The intermediate material should be able to withstand the normal operating temperature of the battery module (e.g., -50°C to 120°C, or -40°C to 90°C).

[0028] The inner layer 26 and the outer layer 25 can be formed of the same material. In this case, since the inner layer 26 is close to the thermal event, the faster heating and expansion of the inner layer 26 causes inward deformation. The inner layer 26 and the outer layer 25 can be formed of different materials. If different materials are used, the inner layer 26 can be made of a material having a higher coefficient of thermal expansion than the material used for the outer layer 25. The materials selected for the inner layer 26 and the outer layer 25 must be able to withstand the normal operating temperature of the battery module and at least the initial temperature from the thermal event. For example, the material used for the inner layer 26 and the outer layer 25 may have a melting point greater than 500°C or at least 600°C, at least 700°C, at least 800°C, at least 900°C, at least 1000°C, or at least 1100°C.

[0029] Examples of materials that can be used to form the inner layer 26 and the outer layer 25 are steel (e.g., stainless steel, such as ferritic stainless steel or austenitic stainless steel; carbon steel; galvanized steel and aluminized steel), zinc, copper, copper-based alloys. For example, the combination of the inner layer 26 and the outer layer 25 can be a coated steel (e.g., carbon steel), wherein the coating can be zinc-based, such as pure Zn, Zn-Fe, Zn-Ni, Zn-Mg, Zn-Mg-Al, or aluminum-based, such as Al-Si or Al-Zn. As another example, the outer layer 25 can be carbon steel and the inner layer can be stainless steel. As another example, both the inner layer 26 and the outer layer 25 can be carbon steel.

[0030] The thickness of the cover can be, for example, greater than 0.4, at least 0.5, at least 0.6, at least 0.7, at least 0.8, at least 0.9, or at least 1 to 5, to 4, to 3, to 2, or to 1.5 millimeters (mm). The inner layer 26 and the outer layer 25 can have the same thickness or different thicknesses. According to an exemplary embodiment, the inner layer 26 is thicker than the outer layer 25. This structure will cause the cover to deflect more inwardly. According to another exemplary embodiment, the inner layer 26 is thinner than the outer layer 25. The thickness of the inner layer 26 and the outer layer 25 can be greater than 0.1, greater than 0.15, greater than 0.2, greater than 0.25, at least 0.3, at least 0.4, at least 0.5, at least 0.6, at least 0.7, at least 0.8 to 4, to 3.5, to 3 mm, respectively.

[0031] The terms "one" and "an" do not indicate a limitation of quantity, but rather indicate the presence of at least one of the referenced items. The term "or" means "and / or", unless the context clearly indicates otherwise. References to "an aspect" throughout the specification mean that a particular element (e.g., feature, structure, step, or characteristic) described in conjunction with that aspect is included in at least one aspect described herein, and may or may not be present in other aspects. In addition, it should be understood that the described elements may be combined in any suitable manner in various aspects.

[0032] When an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

[0033] Unless otherwise indicated herein, all test standards are the most recent standards in effect as of the filing date of the present application or, if priority is claimed, the filing date of the earliest priority application in which the test standards appear.

[0034] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0035] Although the above disclosure has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for its elements without departing from the scope thereof. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the disclosure without departing from the essential scope of the disclosure. Therefore, it is intended that the disclosure is not limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A battery module, comprising: container, a plurality of battery cells within the container, and A cover is attached to the side of the container and extends in a plane above the plurality of battery cells, wherein the cover includes an inner layer and an outer layer.

2. The battery module of claim 1 , further comprising a thermal barrier separating a first group of the plurality of battery cells from a second group of the plurality of battery cells, wherein a gap exists between the cover and top edges of the plurality of battery cells, and the thermal barrier extends upward toward the cover into the gap.

3. The battery module according to claim 1, wherein: The cover deforms inwardly toward the plurality of battery cells upon a thermal event occurring within one or more of the plurality of battery cells.

4. The battery module according to claim 1, wherein: The inner layer is attached to the outer layer at at least two fixed locations at two opposing edges of the cover.

5. The battery module according to claim 4, wherein: The inner layer is attached to the outer layer at one or more additional locations within the perimeter of the cover.

6. The battery module according to claim 5, wherein: The inner layer is attached to the outer layer at one or more additional locations within the perimeter of the cover, including spot welds, by a laminate material located between the inner and outer layers, or by roll bonding.

7. The battery module according to claim 1, wherein: The inner layer comprises a first material and the outer layer comprises a second material, wherein the first material and the second material are metals independently selected for each of the inner layer and the outer layer from steel, copper, and zinc.

8. The battery module according to claim 7, wherein: The thermal expansion coefficient of the inner layer is greater than the thermal expansion coefficient of the outer layer.

9. The battery module according to claim 1, wherein: The cover has a thickness of 0.4 to 5 mm, the inner layer has a thickness of 0.2 to 2.5 mm, and the outer layer has a thickness of 0.1 to 2.5 mm, as long as the thickness of the inner layer is greater than the thickness of the outer layer.

10. The battery module according to claim 1, wherein: The cell cover includes one or more vents to allow gases to exit the module.

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