Debondable adhesive assembly for battery packs

Abstract

The present disclosure provides a "Debondable Adhesive Assembly for a Battery Pack". A debondable adhesive assembly for use in a battery pack includes a UV-curable release layer configured to be disposed between a first battery pack component and a second battery pack component, and an adhesive configured to bond the battery pack component to the second component. The UV-curable release layer is activatable by ultraviolet radiation to reduce the adhesive strength of the adhesive and facilitate debonding of the battery pack component from the second component.

Description

Cross-references to related applications

[0001] This application claims the benefits of U.S. Provisional Applications Nos. 63 / 721,756, 63 / 721,761, 63 / 721,767, 63 / 721,771 and 63 / 721,779, filed November 18, 2024, the disclosures of which are hereby incorporated by reference in their entirety. Technical Field

[0002] This disclosure generally relates to bonded traction battery pack components, and more specifically, to debonded adhesive assemblies. Background Technology

[0003] Adhesives are used in traction battery packs to bond various components together. Sometimes, it may be desirable to remove the adhesive. This removal may be necessary to allow separation of components during battery pack maintenance or repair. Summary of the Invention

[0004] In some aspects, the technology described herein relates to a detangleable adhesive assembly for use in a battery pack, comprising: a UV-curable release layer configured to be disposed between a first battery pack component and a second battery pack component; and an adhesive configured to bond the battery pack component to the second component, wherein the UV-curable release layer can be activated by ultraviolet radiation to reduce the adhesive strength of the adhesive and facilitate the detangle of the battery pack component from the second component.

[0005] In some respects, the technology described herein relates to a debonded adhesive assembly, wherein the first battery pack component is a cell stack; and the second battery pack component is a heat exchange plate of a traction battery pack.

[0006] In some respects, the technology described herein relates to a desandable adhesive assembly, wherein the first battery pack component is a battery cell.

[0007] In some respects, the technology described herein relates to a removable adhesive assembly, wherein the UV-curable release layer comprises 5% to 30% by weight of a silicone diacrylate, 10% to 20% by weight of an alicyclic epoxide, and 6% to 10% by weight of a phosphate.

[0008] In some respects, the technology described herein relates to a detangleable adhesive assembly, wherein the adhesive comprises one or more oligomers selected from the group consisting of siloxane diacrylates, epoxy acrylates, polyurethane acrylates, and polyester acrylates.

[0009] In some respects, the technology described herein relates to a removable adhesive assembly, wherein the UV-curable release layer further comprises an organic peroxide present in an amount of 5% to 6% by weight.

[0010] In some respects, the technology described herein relates to a removable adhesive assembly, wherein the UV-curable release layer comprises a cationic photoinitiator selected from iodonium and phosphonium salts.

[0011] In some respects, the technology described herein relates to a removable adhesive assembly, wherein the UV-curable release layer has a peripheral region that extends beyond the interface between the first battery pack component and the second battery pack component by a distance ranging from 1 mm to 20 mm.

[0012] In some respects, the technology described herein relates to a detangleable adhesive assembly comprising a plurality of discrete segments, each segment bonding one or more individual battery cells of the first battery pack component to the second battery pack component.

[0013] In some respects, the technology described herein relates to a detangleable adhesive assembly that further includes a thermal interface material disposed between the adhesive and the first battery pack component.

[0014] In some aspects, the technology described herein relates to a method for detaching a first battery pack component from a second battery pack component, comprising: exposing a first portion of a UV-curable release layer to ultraviolet radiation, the UV-curable release layer having a second portion extending between the first battery pack component and the second battery pack component; activating the UV-curable release layer to reduce the adhesive strength of the adhesive bonding the first battery pack component to the second battery pack component; and separating the first battery pack component from the second battery pack component.

[0015] In some respects, the technology described herein relates to a method in which exposing the UV-curable release layer to ultraviolet radiation includes directing the ultraviolet radiation to a peripheral region of the UV-curable release layer that extends beyond the interface between the first battery pack component and the second battery pack component.

[0016] In some respects, the techniques described herein relate to a method in which activation of the UV-curable release layer initiates the polymerization of cationic components within the UV-curable release layer.

[0017] In some respects, the technology described herein relates to a method in which the UV-curable release layer comprises 5% to 30% by weight of a silicone diacrylate, 10% to 20% by weight of an alicyclic epoxide, and 6% to 10% by weight of a phosphate.

[0018] In some respects, the techniques described herein relate to a method in which the adhesive comprises one or more oligomers selected from the group consisting of siloxane diacrylates, epoxy acrylates, polyurethane acrylates, and polyester acrylates.

[0019] In some respects, the technology described herein relates to a method in which the UV-curable release layer and the adhesive are part of a removable adhesive assembly, and the method further includes dividing the removable adhesive assembly into a plurality of discrete segments, each segment bonding one or more individual battery cells of the first battery pack component to the second battery pack component.

[0020] In some respects, the technology described herein relates to a method that further includes placing a thermal interface material between the adhesive and the first battery pack component.

[0021] In some respects, the techniques described herein relate to a method in which the UV-curable release layer comprises a cationic photoinitiator selected from iodonium and phosphonium salts.

[0022] In some respects, the techniques described herein relate to a method in which the UV-curable release layer further includes an organic peroxide present in an amount of 5% to 6% by weight.

[0023] In some respects, the technology described herein relates to a method in which the UV-curable release layer has a peripheral region that extends beyond the interface between the first battery pack component and the second battery pack component by a distance ranging from 1 mm to 20 mm. Attached Figure Description

[0024] According to the specific embodiments, various features and advantages of the disclosed examples will become apparent to those skilled in the art. The accompanying drawings of the specific embodiments can be briefly described as follows: Figure 1 A side view of an electrified vehicle with a battery pack is shown.

[0025] Figure 2 It shows Figure 1 An unfolded perspective view of the battery pack.

[0026] Figure 3 The cell stack is shown in Figure 2 The cross-sectional view taken at line 3-3 in the figure.

[0027] Figure 4 It shows Figure 3 A close-up view of the area.

[0028] Figure 5 It shows Figure 4 A close-up view of the area.

[0029] Figure 6 It shows Figure 2 A top view of a battery cell stack inside a housing tray. Detailed Implementation

[0030] This disclosure relates to debonded adhesives and assemblies incorporating such adhesives. In some embodiments, the debonded adhesive bonds components together but can be selectively weakened or peeled off upon exposure to specific stimuli, such as ultraviolet (UV) light, heat, or chemical agents. In the context of battery packs, debonded adhesives are used to bond components such as battery cells, cell holders, modules, thermal barriers, and housing assemblies during manufacturing and assembly.

[0031] Using removable adhesives in battery packs facilitates easier maintenance, repair, or replacement of individual components. Traditional adhesives form relatively permanent bonds that can be difficult to break.

[0032] In some examples, the removable adhesive assembly includes a UV-curable release layer that can be activated upon exposure to UV light. Activation of the release layer causes the adhesive to lose its bond strength and allows the bonded parts to separate without requiring excessive force.

[0033] refer to Figure 1 The electrified vehicle 10 includes a traction battery pack 14, a motor 18, and wheels 22. The battery pack 14 supplies power to the motor 18, which converts electrical energy into mechanical power to drive the wheels 22. The traction battery pack 14 may be a relatively high-voltage battery.

[0034] In an exemplary embodiment, the traction battery pack 14 is fixed to the bottom 26 of the electric vehicle 10. In other examples, the traction battery pack 14 may be located elsewhere on the electric vehicle 10.

[0035] Electrified vehicle 10 is a purely electric vehicle. In other examples, electrified vehicle 10 is a hybrid electric vehicle that selectively uses torque provided by an internal combustion engine (as a replacement or supplement to the electric motor) to drive the wheels. In general, electrified vehicle 10 can be any type of vehicle with a traction battery pack.

[0036] Although the different examples have the specific components shown in the illustrations, the embodiments of this disclosure are not limited to those particular combinations. Some components or features from one example may be used in combination with features or components from another example. In addition, the various drawings accompanying this disclosure are not necessarily drawn to scale, and some features may be enlarged or minimized to show certain details of a particular component or arrangement.

[0037] Now for reference Figure 2 and Figure 3 The example battery pack 14 includes a housing assembly 30 having a cover 34 and a tray 38. The cover 34 is secured to the tray 38 to establish an interior area 42. In this example, the cover 34 may be welded to the tray 38. In other examples, the cover 34 may be secured to the tray 38 using other types of fasteners, such as adhesives or mechanical fasteners. Although an exemplary housing assembly 30 is shown in the figures, the shape, size, and configuration of the housing assembly 30 may vary within the scope of this disclosure.

[0038] The battery pack 14 includes various components housed within an internal region 42. In this example, the components include multiple cell stacks 46, each cell stack including multiple individual battery cells 50 arranged along a respective cell stack axis A and multiple thermal barrier assemblies 56. The cell stacks 46 are clamped between a pair of end plates 58 along the respective cell stack axis A.

[0039] A thermal barrier assembly 56 is sandwiched between groups of battery cells 50 along the cell stack axis A. A group of battery cells 50 may include, for example, four individual battery cells 50. In other examples, a group of battery cells 50 may include other numbers of individual battery cells 50. In some examples, a group of individual battery cells 50 includes a single battery cell within the group of battery cells 50.

[0040] Example battery pack 14 includes four cell stacks 46 within an internal region 42. In other examples, battery pack 14 may employ other numbers of cell stacks 46. Therefore, the teachings of this disclosure should not be regarded as... Figure 2 and Figure 3 The exact configuration shown is illustrated. Furthermore, while the cell stacks 46 of the exemplary embodiment are positioned side-by-side relative to each other within the inner region 42, other configurations are contemplated within the scope of this disclosure. These include, but are not limited to, embodiments in which the cell stacks 46 are stacked on top of each other.

[0041] In an exemplary embodiment, battery cell 50 is a pouch-type lithium-ion cell. However, within the scope of this disclosure, battery cells having other geometries (cylindrical, prismatic, etc.), other chemical substances (nickel-metal hydride, lead-acid, etc.), or both may be used alternatively.

[0042] Now for reference Figures 4 to 6And continue to refer to Figure 2 and Figure 3 Each of the example cell stacks 46 is mounted on a heat exchange plate 60. Coolant can circulate through the heat exchange plate 60 to manage the thermal levels in the battery cells 50 and other components.

[0043] In this example, a desiccant adhesive assembly 64 is used to secure each of the cell stacks 46 (one type of battery component) to one of the heat exchange plates 60 (another type of battery component). The example desiccant adhesive assembly 64 includes a UV release layer 68 and adhesive 72 disposed on both sides of the UV release layer 68. In some examples, a thermal interface material may be positioned between the desiccant adhesive assembly 64 and the cell stacks 46, or between the desiccant adhesive assembly 64 and the heat exchange plate 60.

[0044] UV release layer 68 is UV-curable. For the purposes of this disclosure, "UV release layer" refers to a layer that undergoes a chemical change when exposed to ultraviolet (UV) radiation that supports or promotes the release of an adhesive. This process is known as UV curing, in which the layer is activated by UV light to reduce adhesive strength and allow separation of the bonded parts.

[0045] The UV release layer 68 can be activated by UV radiation to reduce the adhesion strength of the adhesive 72 and promote the debonding of the cell stack 46 from the heat exchange plate 60. To activate the UV release layer 68, it can be exposed to UV radiation emitted from UV light 80 (see...). Figure 6 ).

[0046] The removable adhesive assembly 64 can be a film having thin pressure-sensitive adhesive layers applied to both sides. The removable adhesive assembly 64 can be used as a base layer prior to the application of structural adhesives, gap-filling adhesives, and other sealants.

[0047] In this example, the removable adhesive assembly 64 includes a peripheral region 76 that protrudes beyond the interface distance D between the cell stack 46 and the heat exchange plate 60. In this example, the distance D is a few millimeters, for example, in the range of 1 to 20 millimeters. In a specific example, the distance D is 10 millimeters. The peripheral region 76 is exposed and not positioned between the cell stack 46 and the heat exchange plate 60.

[0048] In this example, UV light 80 directs UV radiation onto the peripheral region 76 to activate the UV stripping layer 68. UV light 80 can direct UV radiation onto the peripheral region 76 for, for example, one minute or two minutes.

[0049] After activation, the UV light 80 can then be removed, but the activation of the UV release layer 68 induced by UV radiation continues to propagate along interface I through the UV release layer 68. After a period of time, the activation of the UV release layer 68 has sufficiently disrupted the bond between the cell stack 46 and the heat exchange plate 60, allowing the cell stack 46 or individual battery cells 50 to be removed and replaced or repaired. In some examples, activation may take several days to disrupt the bond, allowing the cell stack 46 or individual battery cells 50 to be removed.

[0050] In some examples, the debonded adhesive assembly 64 may be divided into several segments, each segment bonding one or more battery cells 50 to the heat exchange plate 60. In such examples, one or more segments may be activated to facilitate the removal of one or more battery cells 50 instead of the entire cell stack 46.

[0051] Activation-initiated polymerization of UV release layer 68. In some examples, the chemicals of UV release layer 68 may include cationic components (such as iodonium and phosphonium salts) to initiate cationic polymerization that does not require UV exposure of the area of ​​UV release layer 68 within and covered by interface I. In some examples, 0.5 to 1 second of UV exposure is sufficient to decompose the cationic photoinitiator to initiate polymerization. The use of cationic chemicals in photoinitiation promotes complete polymerization of the cationic components. Extending the UV coating a few millimeters beyond interface I provides an exposure area that allows UV radiation to initiate cationic polymerization of the covered area along interface I.

[0052] In some examples, adhesive 72 may comprise oligomers of silicone diacrylates that peel and detach upon UV exposure. Adhesive 72 may alternatively or additionally comprise oligomers of epoxy acrylates, polyurethane acrylates, polyester acrylates, or some combination thereof. Adhesive 72 may additionally comprise alicyclic epoxides that provide mechanical properties.

[0053] In some examples, the UV release layer 68 may be 5% to 30% by weight of a silicone diacrylate, 10% to 20% by weight of an alicyclic epoxide, and 6% to 10% by weight of a phosphate. In some examples, these cationic photoinitiators may be obtained as a 50% salt solution in a solvent (such as propylene carbonate). The silicone diacrylate may provide peeling or debonding upon UV exposure in the peripheral region 76. The alicyclic epoxide and phosphate may provide curing in the covered areas that are inaccessible to UV radiation at interface I.

[0054] The UV stripping layer 68 may additionally include 5% to 6% by weight of organic peroxides to provide free radicals upon exposure to heat energy, which is not solely dependent on exposure to UV radiation.

[0055] In some examples, the binder may incorporate a type I photoinitiator, a type II photoinitiator, or both, as well as an amine synergist (such as a tertiary amine) to enhance free radical polymerization.

[0056] Although described in conjunction with cell stack 46 and heat exchange plate 60, the battery pack components bonded by the desiccant adhesive assembly can be any suitable element within the battery pack, and are not limited to battery cells or heat exchange plates. For example, battery pack components may include cell holders, module frames, thermal barriers, housing covers, trays, busbars, control modules, or other structural or functional components common in battery packs. For instance, the desiccant adhesive assembly can bond a housing tray to a housing cover. The desiccant adhesive assembly is suitable for use with a wide variety of battery pack components, thereby facilitating the maintainability, repair, or replacement of various components within the battery pack architecture.

[0057] According to another exemplary embodiment, the desiccant adhesive assembly can be an adhesive composition incorporating nanoparticles with relatively high thermal conductivity to facilitate heat transfer. The particles may include nanodiamond particles (single or polycrystalline with a size of 30 to 250 nanometers), copper particles, or both. These thermally conductive particles can be incorporated into adhesives used within the battery pack, whether the adhesive is a structural adhesive, a gap-filling adhesive, or a pressure-sensitive adhesive. The thermally conductive particles can also be incorporated into plastic housing components (such as trays) during molding and can be applied as a topcoat after molding. A diamond and copper particle coating can also be applied to the entire outer surface of the battery cell, over the adhesive, over the plastic tray, and over the cooling plate.

[0058] Known structural adhesives contain fillers such as silica, calcium silicate, wollastonite, and alumina, which are not as thermally conductive as, for example, nanodiamond particles. Heat transfer within the battery pack can be increased by incorporating diamond nanoparticles and / or copper nanoparticles into the adhesive composition or by applying a diamond coating to the surrounding surfaces above the battery cell, plastic tray, metal parts, or within the dielectric layer.

[0059] In another exemplary embodiment, debonding of the adhesive in the battery pack is facilitated by placing mechanical barriers between the cells. The mechanical barriers can be metallic or non-metallic. Example metallic barriers can be any metal with thermal conductivity for heat dissipation. Example non-metallic barriers are shrink-fit films based on polyester, polycarbonate, or polyvinylidene fluoride (PVDF). PVDF is a dielectric and can help minimize dielectric losses within the battery pack.

[0060] In a specific example, a heat-release hot-melt adhesive film is glazed on both sides of a shrink film. The resulting structure is then wrapped around each battery cell. The surface of the hot-melt shrink film faces the battery cell on a first side and the structural adhesive on the opposite second side. Melting the hot-melt adhesive film allows the battery cells to detach.

[0061] In another exemplary embodiment, an inert resin is incorporated into the adhesive used to bond components of the battery pack. The inert resin can facilitate thermal debonding of the adhesive. The inert resin can be a resin that debonds by heat and bonds by cooling. The inert resin can be a non-crosslinked resin that provides barrier properties. Example: The inserted resin does not interfere with or reduce the functional properties required of the adhesive.

[0062] Structural adhesives currently supplied by adhesive manufacturers are typically based on chemicals that crosslink to form a network that is difficult to detangle, especially when the filler content is relatively high. Incorporating inert resins into structural adhesives without sacrificing the adhesive's crosslinking ability or the barrier properties of adhesive residues in the system can promote detangle formation through heat or radiation exposure (such as UV).

[0063] The foregoing description is exemplary in nature and not restrictive. Variations and modifications made to the disclosed examples will become apparent to those skilled in the art, and such variations and modifications do not necessarily depart from the spirit of this disclosure. Therefore, the scope of protection accorded to this disclosure can only be determined by studying the following claims.

[0064] According to the embodiments of the invention described above, the invention is further characterized in that a thermal interface material is disposed between the adhesive and the first battery pack component.

[0065] According to embodiments of the invention described above, the UV-curable release layer comprises a cationic photoinitiator selected from iodonium salts and phosphonium salts.

[0066] According to embodiments of the invention described above, the UV-curable release layer further includes an organic peroxide present in an amount of 5% to 6% by weight.

Claims

1. A removable adhesive assembly for use in a battery pack, comprising: A UV-curable release layer is configured to be disposed between a first battery pack component and a second battery pack component; as well as An adhesive configured to bond the battery pack component to the second component, wherein the UV-curable release layer is activated by ultraviolet radiation to reduce the adhesive strength of the adhesive and facilitate the detachment of the battery pack component from the second component.

2. The desandable adhesive assembly according to claim 1, wherein the first battery pack component is a cell stack; and the second battery pack component is a heat exchange plate of a traction battery pack.

3. The detachable adhesive assembly as claimed in claim 1, wherein the first battery pack component is a battery cell.

4. The removable adhesive assembly according to claim 1, wherein the UV-curable release layer comprises 5% to 30% by weight of siloxane diacrylate, 10% to 20% by weight of alicyclic epoxide and 6% to 10% by weight of phosphate.

5. The removable adhesive assembly of claim 1, wherein the adhesive comprises one or more oligomers selected from the group consisting of siloxane diacrylates, epoxy acrylates, polyurethane acrylates, and polyester acrylates.

6. The removable adhesive assembly of claim 1, wherein the UV-curable release layer further comprises an organic peroxide present in an amount of 5% to 6% by weight, and optionally, wherein the UV-curable release layer comprises a cationic photoinitiator selected from iodonium salts and phosphonium salts.

7. The removable adhesive assembly of claim 1, wherein the UV-curable release layer has a peripheral region extending beyond the interface between the first battery pack component and the second battery pack component by a distance ranging from 1 mm to 20 mm.

8. The removable adhesive assembly of claim 1, wherein the removable adhesive assembly comprises a plurality of discrete segments, each segment bonding one or more individual battery cells of the first battery pack component to the second battery pack component.

9. The desandable adhesive assembly of claim 1, further comprising a thermal interface material disposed between the adhesive and the first battery pack component.

10. A method for detaching a first battery pack component from a second battery pack component, comprising: A first portion of a UV-curable release layer is exposed to ultraviolet radiation, the UV-curable release layer having a second portion extending between the first battery pack component and the second battery pack component; Activate the UV-curable release layer to reduce the adhesive strength of the adhesive that bonds the first battery pack component to the second battery pack component; as well as Separate the first battery pack component from the second battery pack component.

11. The method of claim 10, wherein exposing the UV-curable release layer to ultraviolet radiation includes directing ultraviolet radiation to a peripheral region of the UV-curable release layer, the peripheral region extending beyond the interface between the first battery pack component and the second battery pack component, and optionally, wherein activating the UV-curable release layer initiates polymerization of the cationic components within the UV-curable release layer.

12. The method of claim 10, wherein the UV-curable release layer comprises 5% to 30% by weight of siloxane diacrylate, 10% to 20% by weight of alicyclic epoxide, and 6% to 10% by weight of phosphate.

13. The method of claim 10, wherein the adhesive comprises one or more oligomers selected from the group consisting of siloxane diacrylates, epoxy acrylates, polyurethane acrylates, and polyester acrylates.

14. The method of claim 10, wherein the UV-curable release layer and the adhesive are part of a removable adhesive assembly, and the method further comprises dividing the removable adhesive assembly into a plurality of discrete segments, each segment bonding one or more individual battery cells of the first battery pack component to the second battery pack component.

15. The method of claim 10, wherein the UV-curable release layer has a peripheral region that extends beyond the interface between the first battery pack component and the second battery pack component by a distance ranging from 1 mm to 20 mm.

Images