Removable adhesive assembly for battery pack

Abstract

A removable adhesive assembly for use in a battery pack includes a UV-curable release layer configured to be positioned 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 activated by ultraviolet radiation to reduce the adhesive strength and facilitate separation of the battery pack component from the second component.

Description

CROSS-REFERENCE TO RELATED REGISTRATIONS

[0001] This application claims the benefit of preliminary US applications Nos. 63 / 721,756; 63 / 721,761; 63 / 721,767; 63 / 721,771; and 63 / 721,779, each filed on November 18, 2024, the disclosures of which are hereby incorporated in full by reference. AREA OF TECHNOLOGY

[0002] This disclosure relates generally to the bonding of traction battery pack components and in particular to detachable adhesive assemblies. GENERAL STATE OF THE ART

[0003] Adhesives are used in traction battery packs to bond various components together. Occasionally, it may be necessary to loosen the adhesive. This might be required to separate the components during maintenance or repair of the battery pack. SUMMARY

[0004] In some aspects, the techniques described herein relate to a removable adhesive assembly for use in a battery pack, comprising: a UV-curable release layer configured to be positioned 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 is activatable by ultraviolet radiation to reduce the adhesive strength and facilitate separation of the battery pack component from the second component.

[0005] In some aspects, the techniques described herein relate to a detachable adhesive assembly, wherein the first battery pack component is a cell stack; and the second battery pack component is a heat exchanger plate of a traction battery pack.

[0006] In some aspects, the techniques described herein relate to a detachable adhesive assembly, where the first battery pack component is a battery cell.

[0007] In some aspects, the techniques described herein relate to a releasable adhesive assembly, wherein the UV-curable release layer comprises 5 to 30 wt% silicone diacrylate, 10 to 20 wt% cycloaliphatic epoxy and 6 to 10 wt% phosphate salt.

[0008] In some aspects, the techniques described herein relate to a soluble adhesive assembly, wherein the adhesive comprises one or more oligomers selected from a group consisting of silicone diacrylate, epoxy acrylate, urethane acrylate and polyester acrylate.

[0009] In some aspects, the techniques described herein relate to a soluble adhesive assembly, wherein the UV-curable release layer further includes an organic peroxide present in an amount of 5 to 6 percent by weight.

[0010] In some aspects, the techniques described herein relate to a soluble adhesive assembly, wherein the UV-curable release layer includes a cationic photoinitiator selected from iodonium salts and phosphonium salts.

[0011] In some aspects, the techniques described herein relate to a removable adhesive assembly, wherein the UV-curable release layer has a circumferential area extending beyond an interface between the first and second battery pack components by a distance in the range of 1 to 20 millimeters.

[0012] In some aspects, the techniques described herein relate to a detachable adhesive assembly, wherein the detachable adhesive assembly comprises a plurality of separate sub-assemblies, each sub-assembly bonding one or more individual battery cells of the first battery pack component to the second battery pack component.

[0013] In some aspects, the techniques described herein relate to a removable adhesive assembly which further includes a thermally conductive material positioned between the adhesive and the first battery pack component.

[0014] In some aspects, the techniques described herein relate to a method for separating a first battery pack component from a second battery pack component, which includes: exposing a first section of a UV-curable separator to ultraviolet radiation, wherein the UV-curable separator has a second section extending between the first battery pack component and the second battery pack component; activating the UV-curable separator to reduce the adhesive strength of an 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 aspects, the techniques described herein relate to a process in which the exposure of the UV-curable separator to ultraviolet radiation involves directing ultraviolet radiation onto a circumferential area of ​​the UV-curable separator that extends beyond an interface between the first battery pack component and the second battery pack component.

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

[0017] In some aspects, the techniques described herein relate to a process in which the UV-curable release layer comprises 5 to 30 wt% silicone diacrylate, 10 to 20 wt% cycloaliphatic epoxy and 6 to 10 wt% phosphate salt.

[0018] In some aspects, the techniques described herein relate to a process wherein the adhesive includes one or more oligomers selected from a group consisting of silicone diacrylate, epoxy acrylate, urethane acrylate and polyester acrylate.

[0019] In some aspects, the techniques described herein relate to a process wherein the UV-curable release layer and the adhesive are parts of a releasable adhesive assembly, and further comprising subdividing the releasable adhesive assembly into a plurality of separate sub-parts, each sub-part bonding one or more individual battery cells of the first battery pack component to the second battery pack component.

[0020] In some aspects, the techniques described herein relate to a procedure that further involves the arrangement of a thermally conductive material between the adhesive and the first battery pack component.

[0021] In some aspects, the techniques described herein relate to a process in which the UV-curable separating layer includes a cationic photoinitiator selected from iodonium salts and phosphonium salts.

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

[0023] In some aspects, the techniques described herein relate to a process wherein the UV-curable separating layer has a circumferential area extending beyond an interface between the first battery pack component and the second battery pack component by a distance in a range of 1 to 20 millimeters. 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, partially expanded view of the battery pack of the Fig. 1. Fig. Figure 3 illustrates a cross-sectional view through a stack of cells along line 3-3 in Fig. 2. Fig. Figure 4 illustrates a close-up view of an area of ​​the Fig. 3. Fig. Figure 5 illustrates a close-up view of an area of ​​the Fig. 4. Fig. Figure 6 illustrates a top view of one of the cell stacks of the Fig. 2 within an enclosing shell. DETAILED DESCRIPTION

[0025] This disclosure relates to releasable adhesives and assemblies containing such adhesives. In some embodiments, the releasable adhesives bond components but can be selectively weakened or dissolved when exposed to a specific stimulus, such as ultraviolet (UV) light, heat, or chemical agents. In the context of battery packs, releasable adhesives are used to bond components, such as battery cells, cell holders, modules, thermal barriers, and casing assemblies, during manufacturing and assembly.

[0026] The use of releasable adhesives in battery packs can simplify maintenance, repair, or replacement of individual components. Conventional adhesives form comparatively permanent bonds that can be difficult to break.

[0027] In some examples, a releasable adhesive assembly includes a UV-curable release layer that can be activated when exposed to UV light. Activating the release layer causes the adhesive to lose its bond strength, allowing the bonded components to be separated without excessive force.

[0028] With reference to Fig. Figure 1 includes an electrified vehicle 10, a traction battery pack 14, an electric motor 18, and wheels 22. The 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] With reference to the Fig. 2 and Fig. Figure 3 shows that the exemplary battery pack 14 includes an enclosure assembly 30 comprising a cover 34 and a shell 38. The cover 34 is attached to the shell 38 to form an interior space 42. In this example, the cover 34 may be welded to the shell 38. In other examples, the cover 34 could be attached to the shell 38 using other types of connections, such as adhesive or mechanical fasteners. While an exemplary enclosure assembly 30 is shown in the drawings, the enclosure assembly 30 may vary in size, shape, and configuration within the scope of this disclosure.

[0033] The battery pack 14 includes various components housed within the interior 42. In this example, the components include a plurality of cell stacks 46, each containing a plurality of individual battery cells 50 and a plurality of thermal barrier assemblies 56, arranged along a respective cell stack axis A. The cell stacks 46 are inserted along their respective cell stack axis A between a pair of end plates 58.

[0034] The thermal barrier assemblies 56 are inserted between groups of battery cells 50 along the cell stack axis A. The groups of battery cells 50 can, for example, contain four individual battery cells 50. In other examples, the groups of battery cells 50 could contain a different number of individual battery cells 50. In some examples, the group of individual battery cells 50 contains a single battery cell 50.

[0035] The exemplary battery pack 14 includes four cell stacks 46 within the interior 42. The battery pack 14 could employ a different number of cell stacks 46 in other examples. Thus, the teachings of this revelation should not be considered in relation to the exact configuration shown in the Fig. 2 and Fig. Figure 3 shows that while the cell stacks 46 of the exemplary embodiment are positioned side by side within the interior area 42, other configurations within the scope of this disclosure are also considered. This includes, among others, embodiments in which the cell stacks 46 are stacked on top of each other.

[0036] In the exemplary embodiment, the battery cells are 50 lithium-ion pouch cells. Alternatively, however, battery cells having other geometries (cylindrical, prismatic, etc.), other chemical compositions (nickel-metal hydride, lead-acid, etc.), or both, could be used within the scope of protection of this disclosure.

[0037] With reference to the Fig. 4-6 and with continued reference to the Fig. 2 and Fig. In Figure 3, the exemplary cell stacks 46 are each arranged on a heat exchanger plate 60. A coolant can circulate through the heat exchanger plate 60 to regulate thermal energy levels in the battery cells 50 and other components.

[0038] In this example, a removable adhesive assembly 64 is used to attach each of the cell stacks 46, a type of battery component, to one of the heat exchange plates 60, another type of battery component. The exemplary removable adhesive assembly 64 includes a UV release layer 68 and an adhesive 72 arranged on both sides of the UV release layer 68. In some examples, a thermally conductive material could be positioned between the removable adhesive assembly 64 and the cell stack 46 or between the removable adhesive assembly 64 and the heat exchange plate 60.

[0039] The 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, which enables or facilitates the release of an adhesive. This process is known as UV curing, in which the layer is activated by UV light to reduce the adhesive strength and allow the separation of bonded components.

[0040] The UV release layer 68 can be activated by UV radiation to reduce the adhesive strength of the adhesive 72 and to facilitate the separation of the cell stack 46 from the heat exchanger plate 60. To activate the UV release layer 68, it can be exposed to UV radiation emitted by a UV light 80 (see Fig. 6).

[0041] The releasable adhesive assembly 64 can be a film with a thin layer of pressure-sensitive adhesive applied to both sides. The releasable adhesive assembly 64 can be used as a base layer before applying assembly adhesives, gap-filling adhesives, and other sealants.

[0042] In this example, the releasable adhesive assembly 64 includes a circumferential region 76 that projects a distance D beyond an interface I between the cell stacks 46 and the heat exchange plate 60. In this example, the distance D is a few millimeters, approximately in a range of 1 to 20 millimeters. In a specific example, the distance D is 10 millimeters. The circumferential region 76 is exposed and not located between the cell stack 46 and the heat exchange plate 60.

[0043] In this example, the UV light 80 directs UV radiation onto the circumferential area 76 to activate the UV separating layer 68. The UV light 80 can direct the UV radiation onto the circumferential area 76 for approximately one or two minutes.

[0044] After activation, the UV light 80 can then be removed, but the activation of the UV separator 68 initiated by the UV radiation continues to propagate along the interface I through the UV separator 68. After some time, the activation of the UV separator 68 has sufficiently disrupted the bond between the cell stack 46 and the heat exchanger plate 60, so that the cell stack 46 or individual battery cells 50 can be removed and replaced or serviced. In some cases, it may take several days for the activation to disrupt the bond, allowing the cell stack 46 or individual battery cells 50 to be removed.

[0045] In some examples, the removable adhesive assembly 64 could be subdivided to include several sections, each of which bonds one or more battery cells 50 to the heat exchanger plate 60. In such examples, one or more sections could be activated to facilitate the removal of one or more battery cells 50 instead of the entire cell stack 46.

[0046] Activation of the UV release layer 68 initiates polymerization. In some examples, the chemistry of the UV release layer 68 may include cationic components, such as iodonium and phosphonium salts, to initiate cationic polymerization, which does not require UV exposure for the areas of the UV release layer 68 that are within and covered by interface I. In some examples, 0.5 seconds to 1 second of UV exposure is sufficient to degrade the cationic photoinitiator and initiate polymerization. The use of cationic chemistry for photoinitiation facilitates complete polymerization of the cationic components. By extending the UV coating a few millimeters beyond interface I, an exposed area is provided that allows UV light to initiate cationic polymerization of the covered areas along interface I.

[0047] In some examples, adhesive 72 may contain oligomers of silicone diacrylate that separate and dissolve upon UV exposure. Alternatively, or additionally, adhesive 72 may contain oligomers of epoxy acrylate, urethane acrylate, polyester acrylate, or a combination thereof. Adhesive 72 may also contain cycloaliphatic epoxy, which provides mechanical properties.

[0048] In some examples, the UV separation layer 68 can contain 5 to 30 wt% silicone diacrylate, 10 to 20 wt% cycloaliphatic epoxy, and 6 to 10 wt% phosphate salt. These cationic photoinitiators are available in some examples as a 50% salt solution in a solvent, such as propylene carbonate. The silicone diacrylate can provide separation or dissolution upon UV exposure in the perimeter area 76. The cycloaliphatic epoxy and phosphate salt can provide curing in the covered areas of interface I, which cannot be reached by UV radiation.

[0049] The UV separating layer 68 can additionally contain 5 to 6 percent by weight of organic peroxide to provide the free radical upon exposure to heat energy, which does not depend solely on exposure to UV radiation.

[0050] In some examples, the adhesive may contain type I photoinitiators, type II photoinitiators, or both together with an amine synergist, such as a tertiary amine, to increase free radical polymerization.

[0051] While described in connection with the cell stacks 46 and the heat exchanger plate 60, the battery pack component bonded by the removable adhesive assembly can be any suitable element within the battery pack and is not limited to a battery cell or a heat exchanger plate. For example, the battery pack component could include cell holders, module frames, thermal barriers, casing covers, trays, busbars, control modules, or other structural or functional components commonly found in battery packs. The removable adhesive assembly could, for example, bond the casing tray to the casing cover. The removable adhesive assembly is adaptable for use with a wide variety of battery pack components, thus facilitating the serviceability, repair, or replacement of various elements within the battery pack architecture.

[0052] A releasable adhesive assembly according to another exemplary embodiment can be an adhesive composition containing nanoparticles with relatively high thermal conductivity to facilitate heat energy transfer. The particles can include nanodiamond particles (monocrystalline or polycrystalline with a size of 30 to 250 nanometers), copper particles, or both. These thermally conductive particles could be included in adhesives used within a battery pack, regardless of whether the adhesive is an assembly adhesive, a gap-filling adhesive, or a pressure-sensitive adhesive. The thermally conductive particles could also be integrated into the plastic encapsulation components, such as shells, during molding and could be applied as a top layer after molding.The diamond and copper particle coating could also be applied to the entire outer surface of the battery cells, over the adhesives, over the plastic shell, over the cooling plates.

[0053] Common assembly adhesives contain fillers such as silicon dioxide, calcium silicate, wollastonite, and aluminum oxide, which are not as thermally conductive as, for example, nanodiamond particles. Integrating diamond and / or copper nanoparticles within the adhesive composition or applying a diamond coating to the surrounding surfaces above the battery cell, the plastic casing, and the metal parts within the dielectric layers can increase heat transfer within the battery pack.

[0054] In another exemplary embodiment, the removal of adhesives in a battery pack is facilitated by placing mechanical barriers between the cells. These mechanical barriers can be metal or non-metal. An exemplary metal barrier could be any metal with thermal conductivity for heat dissipation. An exemplary non-metallic barrier is a heat-shrink tubing film based on polyester, polycarbonate, or polyvinylidene fluoride (PVDF). PVDF is a dielectric and could help minimize dielectric loss within the pack.

[0055] In a specific example, a thermally soluble hot melt adhesive film is applied to both sides of a shrink film. The resulting assembly is then wrapped around each battery cell. The hot melt and shrink film surfaces face a mounting adhesive on one side of the battery cell and a mounting adhesive on the opposite side. Melting the hot melt adhesive film releases the battery cells.

[0056] In another exemplary embodiment, an inert resin is integrated into an adhesive that bonds components of a battery pack. The inert resin can facilitate thermal dissolution of the adhesive. The inert resin can be a resin that dissolves upon heat and bonds upon cooling. The inert resin can be a resin that does not crosslink but provides barrier properties. The exemplary inert resin does not impair the reduction of requirements for the functional properties of the adhesive.

[0057] Current assembly adhesive(s) supplied by adhesive manufacturers are typically based on chemicals that crosslink to form a network that is difficult to remove, especially with a relatively high filler content. Incorporating an inert resin into the assembly adhesive, without sacrificing the adhesive's crosslinking ability or the barrier properties of the adhesive residues in the system, can facilitate removal by heat or radiation exposure, such as UV radiation.

[0058] The preceding description is exemplary and not limiting. Variations and modifications of the disclosed examples may be apparent to a person skilled in the art, which 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.

[0059] According to one embodiment of the above invention, the invention is further characterized by arranging a thermally conductive material between the adhesive and the first battery pack component.

[0060] According to one embodiment of the above invention, the UV-curable separating layer comprises a cationic photoinitiator selected from iodonium salts and phosphonium salts.

[0061] According to one embodiment of the above invention, the UV-curable release layer further comprises an organic peroxide present in an amount of 5 to 6 percent by weight. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 721,756

[0001] US 63 / 721,761

[0001] US 63 / 721,767

[0001] US 63 / 721,771

[0001] US 63 / 721,779

[0001]

Claims

[1] Detachable adhesive assembly for use in a battery pack, comprising: a UV-curable separating layer configured to be positioned 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 is activatable by ultraviolet radiation to reduce the adhesive strength and facilitate the separation of the battery pack component from the second component. [2] Detachable 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 exchanger plate of a traction battery pack. [3] Detachable adhesive assembly according to claim 1, wherein the first battery pack component is a battery cell. [4] Soluble adhesive assembly according to claim 1, wherein the UV-curable release layer comprises 5 to 30 wt% silicone diacrylate, 10 to 20 wt% cycloaliphatic epoxy and 6 to 10 wt% phosphate salt. [5] Releasable adhesive assembly according to claim 1, wherein the adhesive comprises one or more oligomers selected from the group consisting of silicone diacrylate, epoxy acrylate, urethane acrylate and polyester acrylate. [6] Soluble adhesive assembly according to claim 1, wherein the UV-curable release layer further comprises an organic peroxide present in an amount of 5 to 6 percent by weight, and wherein the UV-curable release layer optionally comprises a cationic photoinitiator selected from iodonium salts and phosphonium salts. [7] Removable adhesive assembly according to claim 1, wherein the UV-curable release layer has a circumferential area extending beyond an interface between the first and the second battery pack component by a distance in a range of 1 to 20 millimeters. [8] Detachable adhesive assembly according to claim 1, wherein the detachable adhesive assembly comprises a plurality of separate parts, each part bonding one or more individual battery cells of the first battery pack component to the second battery pack component. [9] Detachable adhesive assembly according to claim 1, further comprising a thermally conductive material arranged between the adhesive and the first battery pack component. [10] Method for separating a first battery pack component from a second battery pack component, comprising: Exposure of a first section of a UV-curable separator to ultraviolet radiation, wherein the UV-curable separator has a second section 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 an 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. [11] Method according to claim 10, wherein the exposure of the UV-curable separator to ultraviolet radiation comprises directing ultraviolet radiation onto a circumferential region of the UV-curable separator extending beyond an interface between the first battery pack component and the second battery pack component, and wherein the activation of the UV-curable separator optionally initiates a polymerization of cationic components within the UV-curable separator. [12] Method according to claim 10, wherein the UV-curable release layer comprises 5 to 30 wt% silicone diacrylate, 10 to 20 wt% cycloaliphatic epoxy and 6 to 10 wt% phosphate salt. [13] Method according to claim 10, wherein the adhesive comprises one or more oligomers selected from the group consisting of silicone diacrylate, epoxy acrylate, urethane acrylate and polyester acrylate. [14] Method according to claim 10, wherein the UV-curable release layer and the adhesive are parts of a releasable adhesive assembly, and further comprising subdividing the releasable adhesive assembly into a plurality of separate parts, each part bonding one or more individual battery cells of the first battery pack component to the second battery pack component. [15] Method according to claim 10, wherein the UV-curable separating layer has a circumferential area extending beyond an interface between the first battery pack component and the second battery pack component by a distance in a range of 1 to 20 millimeters.

Images