Thermally triggered adhesive release for battery maintenance

Abstract

Aspects of the present disclosure include systems and methods for battery maintenance using thermally triggered adhesive release. An exemplary method may include receiving a battery pack having an adhesive layer at an interface between a cooling plate and a component. A heating fluid is directed through the enclosed volume of the cooling plate, and the temperature of the adhesive layer is measured. In response to determining that the temperature has reached the target temperature, a load is applied to the component until the component is removed.

Description

Technical Field

[0001] The present disclosure relates to battery cell technology, and in particular to heat-triggered adhesive release for battery maintenance. Background Art

[0002] High voltage electrical systems are increasingly used to power onboard functions of mobile and stationary systems. For example, in motor vehicles, the need to increase fuel economy and reduce emissions has led to the development of advanced electric vehicles (EVs). EVs rely on a rechargeable energy storage system (RESS), which typically includes one or more high voltage battery packs and an electric drive train for delivering power from the batteries to the wheels. The battery pack may include any number of interconnected battery modules, depending on the power requirements of a given application. Each battery module includes a collection of conductively coupled electrochemical cells. The battery pack is configured to provide a direct current (DC) output voltage at a level suitable for powering a coupled electrical and / or mechanical load (e.g., an electric motor).

[0003] Modern automotive high-voltage battery packs often use adhesives and sealants to connect structural components and manage various dynamic behaviors inside the battery pack. For example, adhesives can be used to hold battery cells during high acceleration events, to reduce the thermal resistance of gaps between power electronics or battery cells and heat sink components, and / or to restrict gas or liquids within the battery pack from entering specific areas or leaving the battery pack assembly. There are many properties that are important to the performance of adhesives or sealants in batteries, and these properties can vary depending on the needs of a specific application. However, regardless of the primary function of the adhesive, bond strength, overall strength, and Young's modulus are decisive for maintaining the necessary bond to prevent separation of the corresponding joints. Summary of the invention

[0004] In an exemplary embodiment, a vehicle includes an electric motor, a battery pack electrically coupled to the electric motor, and a thermal management system coupled to the battery pack. The thermal management system includes a cooling plate, an upper tray, and a lower tray, the upper tray and the lower tray being coupled to opposing surfaces of the cooling plate to define an enclosed volume therebetween. The thermal management system also includes a memory, computer-readable instructions, and one or more processors for executing the computer-readable instructions. The computer-readable instructions control the one or more processors to perform operations. The operations include modifying at least one of a flow rate and a temperature of a heating fluid through the enclosed volume, measuring a temperature of an adhesive layer of a component coupled to the cooling plate and the battery pack, and in response to determining that the temperature has reached a target temperature, applying a load to the component until the component is removed.

[0005] In addition to one or more features described herein, in some embodiments, applying the load to the component includes applying one or more of a peel load, a shear load, and a tensile load to the component until cohesive failure or adhesive failure of the adhesive layer.

[0006] In some embodiments, the enclosed volume includes one or more fluid flow channels, a fluid inlet, and a fluid outlet for circulation of a heated fluid.

[0007] In some embodiments, modifying at least one of a flow rate and a temperature of the heating fluid through the enclosed volume comprises increasing one or more of the flow rate and the temperature in response to the measured temperature being below a target temperature. In some embodiments, modifying at least one of a flow rate and a temperature of the heating fluid through the enclosed volume comprises decreasing one or more of the flow rate and the temperature in response to the measured temperature being above a target temperature.

[0008] In some embodiments, in response to the temperature of the component being within a predetermined threshold of a thermal limit, the temperature of the component is measured and one or more of the flow rate and temperature of the heating fluid is reduced.

[0009] In another exemplary embodiment, the thermal management system may include a cooling plate, an upper tray, and a lower tray, the upper tray and the lower tray being joined to opposing surfaces of the cooling plate to define an enclosed volume therebetween. The thermal management system may also include a memory, computer-readable instructions, and one or more processors for executing the computer-readable instructions. The computer-readable instructions control the one or more processors to perform operations. The operations include modifying at least one of a flow rate and a temperature of a heating fluid through the enclosed volume, measuring a temperature of an adhesive layer coupled to a component of the cooling plate and the battery pack, and in response to determining that the temperature has reached a target temperature, applying a load to the component until the component is removed.

[0010] In yet another exemplary embodiment, a method for heat-triggered adhesive release for battery maintenance may include receiving a battery pack having an adhesive layer at an interface between a cooling plate and a component. A heating fluid is directed through an enclosed volume of the cooling plate, and a temperature of the adhesive layer is measured. In response to determining that the temperature has reached a target temperature, a load is applied to the component until the component is removed.

[0011] In some embodiments, the adhesive comprises a material having a known bond strength as a function of temperature.

[0012] In some embodiments, directing the heating fluid through the enclosed volume causes convective heat transfer from the heating fluid to the adhesive layer.

[0013] In some embodiments, applying a load to the component includes applying one or more of a peel load, a shear load, and a tensile load to the component until cohesive failure or adhesive failure of the adhesive layer.

[0014] In some embodiments, the enclosed volume includes one or more fluid flow channels, a fluid inlet, and a fluid outlet for circulation of a heated fluid.

[0015] In some embodiments, in response to the temperature of the component being within a predetermined threshold of a thermal limit, the temperature of the component is measured and one or more of the flow rate and temperature of the heating fluid is reduced.

[0016] In some embodiments, preparatory maintenance including disassembly is performed prior to directing the heating fluid through the enclosed volume of the cooling plate.

[0017] In some embodiments, removed components are replaced with new components.

[0018] The above features and advantages and other features and advantages of the present disclosure are apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other features, advantages and details appear, by way of example only, from the following detailed description, which refers to the accompanying drawings, in which:

[0020] Figure 1 is a vehicle configured according to one or more embodiments;

[0021] Figure 2 is a battery pack configured according to one or more embodiments;

[0022] Figure 3 is configured according to one or more embodiments Figure 2 Thermal management system for battery packs;

[0023] Figure 4 is a graph depicting the relationship between bond strength and temperature according to one or more embodiments;

[0024] Figure 5 is a flow chart according to one or more embodiments; and

[0025] Figure 6 A computer system according to one or more embodiments. DETAILED DESCRIPTION

[0026] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or use. It should be understood that throughout the drawings, corresponding reference numerals represent identical or corresponding components and features. As used herein, the term module refers to a processing circuit, which may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality.

[0027] As mentioned earlier, modern automotive high-voltage battery packs typically use adhesives and sealants to connect structural components and manage the dynamic behavior inside the battery pack. Due to the complexity of battery components and packaging constraints, adhesive joints can be very large, spanning up to the order of square meters, and may be inaccessible after the assembly process.

[0028] However, it may be necessary to disassemble, remanufacture, rework, and recycle battery packs and / or individual components (e.g., cells) for maintenance. For example, regular monitoring of the battery's state of health (SOH) is critical to assessing its performance and detecting any potential problems early. Battery pack monitoring involves measuring the capacity, internal resistance, and voltage characteristics of the battery to assess its overall health and remaining life. In some cases, individual cells may deteriorate faster than other cells, resulting in an imbalance in the battery pack. In this case, replacing the degraded battery can help restore the battery's performance. These situations typically require removing localized cells, structural, electrical and thermal components, and / or resolving internal electrical faults (e.g., short circuits). Unfortunately, the size and positioning of bonded joints in a battery pack may make disassembly challenging or impossible when maintaining the battery pack or at the end of its life.

[0029] Furthermore, these procedures are ideally accomplished while minimizing the waste generated when handling all or part of the functional portions of the battery pack. The bonded portions of the battery pack must typically be processed in large modular pieces or sections to avoid damage or breakage of the cells or critical components. Current solutions involve shredding and chemical processing of large assemblies to separate recyclable materials, as well as the use of very weak adhesives that act as fuses during disassembly. These relatively weak adhesives allow for easier maintenance, but push cost, complexity, and mass into other structural components and result in non-optimal designs.

[0030] The present disclosure introduces the use of heat-triggered adhesive release for battery pack maintenance. A method for thermally weakening relatively strong adhesive joints in a battery pack during end-of-life and / or remanufacturing scenarios without sacrificing the performance of the joint design during vehicle operation is described herein, rather than relying on relatively weak adhesives with poor structural and / or stability tradeoffs. In some embodiments, the adhesive joint can be changed from a structural state (relatively high bond strength) to a usable state (relatively low bond strength) by applying targeted heating at the adhesive joint. In some embodiments, heat is applied by flowing a heating fluid (air, coolant, water, etc.) through a manifold, duct, or channel in a structural element of a rechargeable energy storage system (RESS) to heat the surface bonded to the corresponding adhesive joint. The structural element may include, for example, an existing thermal management system of a battery pack, such as a cooling plate.

[0031] In accordance with one or more embodiments, utilizing pre-existing structural elements of a battery pack to deliver a targeted heat-triggered adhesive release provides several technical advantages over other battery pack maintenance methods. Notably, a high-strength adhesive can be used during the life of the battery module / battery pack to improve battery cell retention and stability, which can be selectively removed during the end of life or maintenance without damaging thermal management devices (heat sinks), electrical isolation surfaces, or causing battery rupture. Other advantages are possible. For example, the heating operation provided can be controlled so that the adhesive itself exceeds a specified temperature for a specified breakdown duration without overheating non-target components and structures. In other words, the targeted heating described herein allows the adhesive joint to reach a higher temperature than the rest of the RESS assembly, so that any temperature sensitive components remain within their operating and safety limits.

[0032] According to an exemplary embodiment, the vehicle Figure 1 1. The vehicle 100 is generally indicated at 100. The vehicle 100 is shown in the form of an automobile having a body 102. The body 102 includes a passenger compartment 104, within which a steering wheel, front seats, and rear passenger seats (not shown separately) are arranged. A plurality of components are arranged within the body 102, including, for example, an electric motor 106 (shown by a projection under the front hood). The electric motor 106 is shown only for ease of illustration and discussion. It should be understood that the configuration, location, size, arrangement, etc. of the electric motor 106 are not meant to be particularly limited, and all such configurations (including multi-motor configurations) are within the intended scope of the present disclosure.

[0033] The electric motor 106 is powered via a battery pack 108 (shown by a projection near the rear of the vehicle 100). The battery pack 108 is shown for ease of illustration and discussion only. It should be understood that the configuration, location, size, arrangement, etc. of the battery pack 108 is not meant to be particularly limited, and all such configurations (including separate configurations) are within the intended scope of the present disclosure. In addition, while the present disclosure is primarily discussed in the context of a battery pack 108 configured for an electric motor 106 of the vehicle 100, the aspects described herein may be similarly incorporated within any system (vehicle, building, or other) having an energy storage system (e.g., one or more battery packs or modules), and all such configurations and applications are within the intended scope of the present disclosure.

[0034] During normal operation, the battery cells (see Figure 2 ) must be maintained within regulated temperature ranges (limits) to operate efficiently and prevent damage or degradation (deterioration). These temperature limits are more limited during battery cell operation (such as when the motor 106 is drawing from the battery pack 108) than during non-operating conditions due to the current draw through the battery pack 108 under load.

[0035] When used in automotive applications, adhesives and polymers used in batteries typically have relatively low glass transition temperatures. This is a result of the need to cure battery components at low or room temperature rather than in an oven to limit exposure of the battery cells to high temperatures. In some embodiments, a heat-triggered adhesive release scheme can take advantage of the relatively low glass transition temperature found in automotive adhesives. In particular, the adhesive can be selected so that the glass transition temperature is below the maximum temperature limit of the temperature-sensitive component (e.g., a battery cell) so that the targeted application of heat to the adhesive can soften the adhesive to a low adhesion, high elongation usable state without damaging the component. In this way, the component can be removed without thermal damage. In some embodiments, the targeted application of heat to the adhesive can be directed to the adhesive through a pre-existing thermal management system (e.g., a cooling plate) of the battery pack 108. About Figure 2 and Figure 3 The configuration and use of thermal management systems and cold plates are discussed in more detail.

[0036] Figure 2 A battery pack (eg, Figure 1 An example configuration of a battery pack 108). Figure 2 As shown, the battery pack 108 includes a plurality of battery cells 202 arranged in a battery stack 204. Each of the battery cells 202 in the battery pack 108 generates and stores electrical energy through an exothermic electrochemical reaction. Note that for ease of illustration and discussion, Figure 2 The battery pack 108 is depicted in a disassembled state.

[0037] In some embodiments, the battery pack 108 includes an outer shell or housing 206. The housing 206 is configured to maintain the arrangement of the battery cells 202 in the battery stack 204, protect the battery cells 202 from damage, and facilitate installation of the battery pack 108 in its operating environment (such as in a battery pack as previously discussed). Figure 1 In some embodiments, the housing 206 includes a first side panel 208 , a second side panel 210 , and a cover or top panel 212 attached to the first side panel 208 and the second side panel 210 .

[0038] In some embodiments, the battery pack 108 includes a thermal management system 214 configured to manage heat transfer from the battery pack 204 to the environment. In some embodiments, the thermal management system 214 includes a cooling plate 216 (also referred to as a cold plate). In some embodiments, the thermal management system 214 and / or the cooling plate 216 are attached to the first side plate 208 and / or the second side plate 210 to secure the battery stack 204 within the housing 206.

[0039] In some embodiments, an adhesive layer 218 is applied between the cooling plate 216 and the battery stack 204 to secure the battery stack 204 to the thermal management system 214. As previously described, the adhesive layer 218 can be made of a material selected such that the glass transition temperature of the adhesive layer 218 is lower than the maximum temperature (thermal limit) of one or more temperature sensitive components (e.g., the battery cells 202 of the battery stack 204). In this way, the adhesive layer 218 can be weakened until the component can be easily removed for maintenance, replacement, etc. The heat-triggered adhesive release of the adhesive layer 218 (referred to as "heat-triggered adhesive release") is described in more detail below.

[0040] like Figure 2 As further shown in FIG. 1 , in some embodiments, the battery pack 108 includes a first interconnect board (ICB) 220 and a second interconnect board ICB 222. In some embodiments, the interconnect boards 220, 222 can be attached to the top plate 212, such as pre-assembled with the top plate 212. Thus, the interconnect boards 220, 222, the first side plate 208, the second side plate 210, the top plate 212, and the cooling plate 216 define an enclosure for the battery pack 108.

[0041] In some embodiments, each of the battery cells 202 of the battery stack 204 includes a first terminal 224 (also referred to as an electrical terminal or contact piece) and a second terminal 226, each of which is arranged on an opposite end of the corresponding battery cell, as shown. In some embodiments, one of the first terminal 224 and the second terminal 226 is a positive terminal, and the other terminal is a negative terminal. In some embodiments, the first terminal 224 is electrically coupled to the first interconnect plate 220, and the second terminal 226 is coupled to the second interconnect plate 222.

[0042] Heat triggered adhesive release

[0043] In some embodiments, the adhesive glass transition strength and overall properties of the adhesive layer 218 are formulated such that the adhesive strength and material elongation provide a predetermined (designed) battery cell retention metric for the battery stack 204 at the maximum battery operating temperature, such that the possibility of damage to the battery cell 202 during an impact and / or other high load event does not result in battery damage, while ensuring that the adhesive strength can still be degraded before exceeding the temperature design limit of the battery cell. It is observed that as the material strength begins to degrade below the glass transition temperature, the adhesive strength and hardness will decrease. Figure 4 The relationship between bond (adhesive) strength and temperature is described in more detail.

[0044] In some embodiments, the adhesive layer 218 includes one or more chemical additives and / or release agents. Chemical additives and / or release agents can be selected to provide a reaction that facilitates degradation / removal of the adhesive layer 218. The reaction can be permanent (latching) or temporary. Temporary degradation will require the maintenance process (removal) to be completed while maintaining sufficient adhesive temperature, while the latching reaction will allow the battery pack 108 to cool before the subsystem is removed (i.e., before removing one or more of the battery pack 204 or the battery cell 202). In some embodiments, the latching reaction requires more targeted heating to reduce the accidental degradation of adjacent subsystems. In some embodiments, chemical additives reduce overall material strength and / or surface adhesive bonding, resulting in material failure of the adhesive layer 218 during removal. In some embodiments, a release agent can be applied to a substrate (an attached component, for example, applied to a thermal management system 214, a cold plate 216, a battery stack 204, etc.) before applying the adhesive layer 218. In some embodiments, the release agent can be activated to trigger adhesive failure, thereby causing the adhesive layer 218 to detach from the substrate.

[0045] It is observed that any adhesive heating needs to be provided in a delicate and engineered manner to prevent damage to the battery cells 202, damage to the battery stack 204, and / or reduced life of the battery pack 108. In some embodiments, targeted application of localized heating to the adhesive layer 218 is achieved by flowing a temperature-regulating fluid (air, coolant, etc.) through a pre-existing channel system or manifold that is designed into one or both of the joined components and against which the adhesive layer 218 is applied (e.g., to the interface between the cooling plate 216 and the battery pack 204 on which the adhesive layer 218 is formed and / or deposited). For example, the temperature-regulating fluid may pass through channels in the cooling plate 216.

[0046] Utilizing fluid-based heating directly at the bonding surface allows adhesive layer 218 to be exposed to the thermal energy of the heating process before other components in the system and achieve higher temperatures than other components not in direct contact with the bonding surface.

[0047] Notably, heating the adhesive layer 218 via a pre-existing channel system or manifold in this manner allows for convective heat transfer, providing improved thermal energy control compared to primarily conduction-based heating systems that tend to overheat. For example, conduction-based systems (such as immersion ovens) require heat to be applied externally to the battery pack 108 and therefore do not naturally isolate the adhesive joint from the temperature sensitive components. In another example, while heated probes / wires allow a conductive heat path to be applied directly to the adhesive, these types of systems require excessive heating of the probe / wire to achieve the desired temperature in the adhesive joint, in part because the thermal mass of the probe is significantly lower than the joint being heated. The result is uncontrolled overheating of the sensitive component itself, which also requires physical proximity to the component, which is typically prohibited.

[0048] In some embodiments, the fluid manifold for heating the adhesive layer 218 can be formed using existing structural components (such as the corrugated hollow portions in the cooling plate 216), and / or can be uniquely designed for fluid flow, such as a coolant system or exhaust manifold in any subcomponent / portion of the thermal management system 214 and / or the battery pack 108.

[0049] In some embodiments, to separate the structural thermal interface adhesive for cell retention to the cooling system (i.e., to cause heat-triggered adhesive release of adhesive layer 218), a heated fluid (e.g., air) may be delivered to a manifold in thermal management system 214 and flowed under adhesive layer 218 to increase the temperature of cooling plate 216. As the temperature of the metal material of cooling plate 216 increases, adhesive layer 218 bonds to the surface of cooling plate 216.

[0050] In some embodiments, adhesive layer 218 includes a relatively low interfacial thermal resistance (i.e., lower interfacial thermal resistance than battery stack 204), a relatively low thermal mass (e.g., compared to cooling plate 216 and battery stack 204), and a relatively thin through-plane bond line (i.e., less thickness orthogonal to the heating path than other components). In this manner, adhesive layer 218 will heat at a faster rate than other interface components (e.g., battery stack 204).

[0051] Note that while an adjacent cell (e.g., battery cell 202 of battery stack 204) will initially increase in temperature at a similar rate as adhesive layer 218 due to the high thermal conductivity of the adhesive layer 218 thermal interface, the significantly higher thermal mass of the cell interior and the interfacial resistance through the electrolyte to the cell exterior surface will cause adhesive layer 218 to reach the necessary temperature to enter a usable condition before the cell interior reaches sufficient temperature to trigger damage and / or degradation of the materials inside battery cell 202. Advantageously, the targeted and convective heat transfer properties of the heat-triggered adhesive release described herein allow for significantly faster heating of the bond joint using a lower temperature heat source, allowing for a maximum possible temperature at adhesive layer 218 while remaining within the design (thermally limited) temperature of the battery components.

[0052] In some embodiments, the maintenance transition temperature for removing adhesive layer 218 is set so that the thermal resistance between the temperature sensitive component (electronic device, battery cell, etc.) and the heat source (e.g., a heating fluid delivered via a manifold) is greater than the thermal resistance between adhesive layer 218 and the heat source. Alternatively or additionally, in some embodiments, the maintenance transition temperature may be set taking into account the thermal mass of the temperature sensitive component relative to the thermal mass of adhesive layer 218 so that adhesive layer 218 will reach the use (target or soak) temperature before the temperature sensitive component reaches its thermal limit.

[0053] In some embodiments, thermal analysis (e.g., 3D computational fluid dynamics or CFD) may be performed to determine and / or evaluate time at temperature (also referred to as soak time) and confirm that the flow of heated fluid does not result in time at temperature of temperature sensitive components that may cause denaturation, chemical degradation, and / or melting under one or more estimated varying conditions. The estimated varying conditions may take into account process variations such as adhesive coverage, thickness, flow restrictions, deterioration states requiring maintenance, etc. In some embodiments, thermal analysis includes evaluating the thermal mass of the adhesive joint, degradation temperatures, and adjacent thermal paths in series.

[0054] In some embodiments, the heating of adhesive layer 218 is controlled to ensure that adhesive layer 218 is sufficiently soft during removal so that the delamination force is below a predetermined threshold. For example, the delamination force can be maintained below a threshold above which empirically known adverse effects may occur. These effects may include, for example, plastic deformation, rupture of coolant carrying channels, rupture of combustion gas carrying channels, loss of isolation in dielectric coatings, etc.

[0055] In some embodiments, heating of the adhesive layer 218 is controlled by manipulating the flow rate and / or temperature of a heating fluid through a manifold of the thermal management system 214. In some embodiments, heating of the adhesive layer 218 is controlled so that the temperature of surrounding components (including the component to be removed and adjacent components) does not exceed thermal constraints or critical performance thresholds. For example, if a battery cell exceeds its temperature limit, the battery cell may experience battery cell damage, while exceeding storage and non-operating temperature limits will result in internal degradation of the chemical and electrical components of the battery cell, which will result in a reduction in operating life or charge / discharge performance after a period of time determined by the battery cell design. In another example, exposing other adhesive or seal joints in the battery pack 108 to the maintenance temperatures required to remove the adhesive layer 218 may result in accidental failure and / or accidental release of other components (other modules) in the battery pack 108.

[0056] Once adhesive layer 218 has been soaked at the maintenance transition temperature (a temperature sufficient to reduce the bond strength below a predetermined value), the component (eg, battery stack 204 ) may be removed.

[0057] There are two general techniques for removing the adhesive layer 218 after soaking. First, the target subsystem (e.g., battery stack 204) can be removed using peel, shear, and / or tensile loads, resulting in cohesive or failure adhesive failure of the adhesive layer 218 (depending on the prior art for ensuring adhesive degradation as described above). In some embodiments, the target subsystem is removed by initiating failure of the adhesive layer 218 at the edge of the adhesive layer 218. For example, by applying a force at the edge of the adhesive layer 218 after soaking. In this way, the deflection is maintained in the elastic deformation area of ​​the subsystem / heat sink (e.g., cooling plate 216).

[0058] In some embodiments, prior to removing a subsystem, testing and / or simulation of the process (via, for example, 3D finite element analysis or FEA) may be performed to assess that other systems remaining after maintenance do not experience plastic deformation beyond a predetermined tolerance, and / or that the stress paths acting on adhesive layer 218 prioritize debonding failure in the adhesive material rather than emphasizing progressive failure. In this way, the energy applied to surrounding systems may be reduced.

[0059] Alternatively (secondarily), the target subsystem (e.g., battery stack 204) can be disassembled by cutting adhesive layer 218 using a tool. In some embodiments, a wire cutting method can be used to cut adhesive layer 218 in a similar manner to that performed in other industrial or maintenance applications (e.g., in windshield removal). It is worth noting that cutting adhesive layer 218 can be made easier by reducing the overall or bonding strength (and therefore the hardness) of the adhesive material using the previously described heating method. In some embodiments, ropes, cables, and / or harnesses can be routed around adhesive layer 218 so that the cables / or harnesses surround areas on three or more sides of the target component. In this way, force can be applied to adhesive layer 218, and the target component can be under tension from one or more ends substantially at the same time. In some embodiments, ropes, cables, and / or harnesses are then pulled through adhesive layer 218, thereby cutting the adhesive material and releasing the target subsystem. For charging subsystems where maintaining isolation in the coated surface is critical, in some embodiments, a flange or dielectric separator may be placed on the target subsystem to deflect the cords, cables and / or harnesses toward the mating substrate (adhesive interface) in a manner that adheres to (maintains) design clearance requirements.

[0060] The overall method for heat-triggered adhesive release generally includes the following steps:

[0061] Step 1. During assembly, place adhesive on the surface of the component interface (eg, battery cell, cold plate, etc.) In some embodiments, the adhesive has a known bond strength versus temperature profile.

[0062] Step 2. Mating the two or more parts and wetting the adhesive.

[0063] Step 3. Allowing the adhesive to cure to define an adhesive bond between the two or more components.

[0064] Step 4. Perform necessary disassembly / preparatory maintenance so that the target component (module, battery cell, battery cell array, cold plate, other component) can be removed from the bonded joint.

[0065] Step 5. Flow hot air or heated fluid through the battery cold plate / thermal management system (via, for example, a manifold as previously described). For example, the hot air or heated fluid may be passed through the system at a temperature of 60 degrees Celsius, but other temperatures are within the contemplated scope of the present disclosure.

[0066] Step 6. Monitor the battery cell temperature and / or adhesive temperature.

[0067] Step 7. Once the adhesive joint has reached the target temperature for the desired amount of time, remove the battery cell, module, battery cell array, cold plate, other component, etc.

[0068] Step 8. Clean the system. In some embodiments, residual adhesive material is removed from the interface so that new adhesive can be positioned without interference.

[0069] Step 9. Allow the system to cool.

[0070] Step 10. For maintenance applications, replace the target component with a new component. For example, the removed battery pack 204 (or battery cells, modules, cooling plates, etc.) can be replaced with a new and / or repaired component.

[0071] Figure 3 A thermal management system (eg, Figure 2 Example configuration of a thermal management system 214). Figure 3 As shown, the thermal management system 214 includes a cooling plate 216. In some embodiments, the cooling plate 216 can be operated via air cooling. In some embodiments, the cooling plate 216 can be operated via a cooling fluid (not separately shown).

[0072] In some embodiments, the thermal management system 214 may include an upper tray 302 and a lower tray 304 that can be sealably engaged to opposing surfaces of the cooling plate 216 to define an enclosed volume 306 between the upper tray 302 and the lower tray 304. In some embodiments, the cooling plate 216 may include a peripherally disposed raised lip 308. In some embodiments, the cooling plate 216 and the upper tray 302 may be complementarily shaped to allow for sealable engagement around the perimeter of the cooling plate 216 at the raised lip 308.

[0073] In some embodiments, the enclosed volume 306 may include one or more fluid flow channels 310 and fluid inlet and outlet couplings 312 to enable a cooling fluid (not separately shown) to circulate through the enclosed volume 306. Although not meant to be particularly limited, the cooling fluid may include, for example, air, water, glycols (e.g., ethylene glycol, propylene glycol, etc.), dielectric fluids (e.g., mineral oil, synthetic oil, etc.), fluorinated liquids (e.g., perfluorocarbons (PFCs)), hydrofluoroolefins, coolant mixtures, and / or phase change materials (PCMs).

[0074] As previously mentioned, in some embodiments, heat is applied to the adhesive layer 318 by flowing a heating fluid (air, water, the heated cooling fluid itself, etc.) through pre-existing fluid flow channels 310 provided for the cooling fluid. Alternatively or additionally, in some embodiments, the cooling plate 216 may be provided with one or more dedicated channels (any fluid flow channels 310) reserved specifically for the heating fluid.

[0075] In some embodiments, the cooling plate 216 includes one or more elongated ribs 314 defining a fluid flow channel 310 (also referred to as a coolant or refrigerant circulation tube). In some embodiments, the ribs 314 rise from a bottom surface 316 of the cooling plate 216 to contact an opposite side (not separately shown) of the upper tray 302. In some embodiments, the ribs 314, the upper tray 302, and the raised lip 308 can be complementarily shaped and sealably connected to define the enclosed volume 306.

[0076] In some embodiments, the rib 314 may include one or more through slots 318, and the upper tray 302 may include one or more complementary through slots 320. As used herein, the slots are "complementary" because they are physically aligned (i.e., such that they are vertically stacked). In some embodiments, a sealable joint (not separately shown) is formed around the perimeter of the through slots 318, 320 at the interface of the rib 314 and the upper tray 302.

[0077] The ribs 314 can be arranged as desired, and can be, for example, periodic and discontinuous (as shown). In other embodiments, the ribs 314 can be made of a single shape that is continuous along the length of the ribs 314 (not separately shown).

[0078] In some embodiments, the lower tray 304 serves as a carrier for engagement with the cooling plate 216. In some embodiments, the lower tray 304 can include one or more support ribs 322 that extend upwardly to engage with the underside of the ribs 314. The support ribs 322 can extend transversely (as shown) to the elongated ribs 314 and / or along the length of the ribs 314 (not separately shown). In some embodiments, the lower tray 304 includes an attachment slot 324 to engage with an angled or barbed retention feature (not shown) of an external component (e.g., a portion of the battery pack 108 and / or a mounting structure within the vehicle 100).

[0079] The upper tray 302, the lower tray 304 and the cooling plate 216 can be made of a metal or a metal alloy. For example, in some embodiments, the upper tray 302, the lower tray 304 and / or the cooling plate 216 can be manufactured from a clad aluminum alloy sheet stock. The ribs 314, the through slots 318, 320, the support ribs 322 and / or the attachment slots 324 can be stamped, cut (e.g., by a laser or water jet process), or alternatively manufactured. Variable height features (e.g., ribs 314, raised lips 308, etc.) can be press formed, roll formed, hydraulically formed, or alternatively manufactured. The upper tray 302, the lower tray 304 and the cooling plate 216 can be sealably joined by any effective bonding process (including, for example, brazing).

[0080] Figure 4A graph 400 is shown that depicts the relationship between bond strength (here, measured in MPa along the Y-axis) and temperature (here, measured in degrees Celsius along the X-axis) of an exemplary adhesive according to one or more embodiments. Figure 4 As shown, the bond strength decreases as the temperature of the adhesive increases, as defined by the bond strength curve 402. The bond strength curve 402 is merely illustrative, and it should be readily appreciated that the bond strength curve 402 will vary depending on the adhesive selected for a given application.

[0081] like Figure 4 As further shown in FIG. 4 , there is a maintenance temperature 404 that causes the bond strength of the adhesive to drop below a predetermined removal threshold 406. In some embodiments, the maintenance temperature 404 is the glass transition temperature of the corresponding adhesive, although temperatures above and below the glass transition temperature may be used (note that to facilitate component removal, temperatures below the glass transition temperature should only be used when necessary to prevent thermal loads on the target component and / or other components from exceeding specifications (i.e., when there is insufficient thermal bandwidth to achieve the glass transition temperature without risking component damage and / or degradation). It is observed that the maintenance temperature 404 is below the maximum temperature limit 408 of the temperature sensitive component (the target component and / or another component).

[0082] In some embodiments, the thermal load (heating) of adhesive layer 218 can be actively monitored via attached and / or embedded thermocouples (not separately shown). In some embodiments, incidental heating of the target component and / or any other component can be similarly measured while applying heat to adhesive layer 218.

[0083] In some embodiments, the measured temperature of adhesive layer 218 is compared to a predetermined target, such as maintenance temperature 404. In some embodiments, the measured temperature of the target component and / or any other component may be compared to a predetermined threshold, such as maximum temperature limit 408.

[0084] In some embodiments, the heating fluid (see Figure 3 ) can be changed in response to the measured temperature of adhesive layer 218 and / or the measured temperature of the target component and / or any other component. For example, the temperature and / or flow rate of the heating fluid can be increased to increase heat transfer into adhesive layer 218, or decreased to reduce heat transfer into adhesive layer 218, as needed. In some embodiments, the temperature and / or flow rate of the heating fluid can be actively adjusted until adhesive layer 218 reaches maintenance temperature 404. In some embodiments, the temperature and / or flow rate of the heating fluid can be actively adjusted to maintain maintenance temperature 404 for a designed soak time.

[0085] Reference now Figure 5 , a flowchart 500 for battery maintenance utilizing heat-triggered adhesive release is generally shown according to an embodiment. Although depicted in a particular order, Figure 5 The blocks depicted in the drawings may be rearranged, subdivided, and / or combined.

[0086] At block 502, the method includes receiving a battery pack including an adhesive layer at an interface between a cooling plate and a component. In some embodiments, the adhesive is made of a material having a known bond strength as a function of temperature.

[0087] At block 504, the method includes directing a heating fluid through the enclosed volume of the cooling plate. In some embodiments, directing the heating fluid through the enclosed volume causes convective heat transfer from the heating fluid to the adhesive layer. In some embodiments, the enclosed volume includes one or more fluid flow channels, a fluid inlet, and a fluid outlet for circulation of the heating fluid. The heating fluid can be directed through the enclosed volume of the cooling plate by actuating one or more valves connected to a source of the heating fluid, the source of the heating fluid being connected to the fluid inlet (the source and valves are not shown separately).

[0088] At block 506, the method includes measuring the temperature of the adhesive layer. The temperature may be measured using, for example, a thermocouple.

[0089] At block 508, the method includes: in response to determining that the temperature has reached the target temperature, applying a load to the component until the component is removed. In some embodiments, applying the load to the component includes applying one or more of a peel load, a shear load, and a tensile load to the component until cohesive failure or adhesive failure of the adhesive layer occurs. In some embodiments, a component of the thermal management system can direct the load by activating, directing, or otherwise controlling a device (e.g., an actuator coupled to a pressing structure) to apply the load.

[0090] In some embodiments, the method includes measuring a temperature of the component, and reducing one or more of a flow rate and a temperature of the heating fluid in response to the temperature of the component being within a predetermined threshold of a thermal limit.

[0091] In some embodiments, the method includes performing pre-maintenance, such as disassembly, prior to directing the heating fluid through the enclosed volume of the cooling plate.

[0092] In some embodiments, the method includes replacing the removed component with a new component.

[0093] Figure 6108 and / or battery pack 108. In some embodiments, the computer system 600 may be implemented as an external system (e.g., as a module communicatively coupled to the vehicle 100 and / or the battery pack 108) and / or as an internal system (e.g., as a Figure 1 The computer system 600 may be incorporated into an electronic control unit or ECU of the vehicle 100. In some embodiments, the computer system 600 may be configured to receive signals (eg, adhesive temperature, component temperature, etc.) from one or more battery cells or components of the battery pack.

[0094] The computer system 600 includes at least one processing device 602, which typically includes one or more processors for performing various functions, such as controlling a motor (e.g., Figure 1 106 ) to one or more wheels of a vehicle (e.g., vehicle 100 ), controlling one or more batteries (e.g., Figure 1 The invention can also be used to control the charge / discharge rate of the battery pack 108), control the delivery (temperature and flow rate) of a heating fluid to an adhesive layer (e.g., adhesive layer 218), and / or monitor the state (e.g., temperature) of the adhesive or any other component of the battery pack (e.g., a battery cell).

[0095] Components of computer system 600 include a processing device 602, such as one or more processors or processing units, a system memory 604, and a bus 606 that couples various system components including system memory 604 to processing device 602. System memory 604 may include various computer system readable media. Such media may be any available media that can be accessed by processing device 602, and includes both volatile and nonvolatile media and removable and non-removable media.

[0096] For example, system memory 604 includes non-volatile memory 608, such as a hard drive, and may also include volatile memory 610, such as random access memory (RAM) and / or cache memory. Computer system 600 may also include other removable / non-removable, volatile / non-volatile computer system storage media.

[0097] The system memory 604 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments described herein. For example, the system memory 604 stores various program modules that generally perform the functions and / or methods of the embodiments described herein. One or more modules 612, 614 may be included to perform functions related to the monitoring and / or control of the battery pack 108, for example, determining one or more current battery temperatures, the current state of charge of the battery pack 108 and / or any battery of the battery pack 108, the charging duration, the charging current and / or voltage, etc. The computer system 600 is not limited thereto, because other modules may be included depending on the desired function of the vehicle 100. As used herein, the term "module" refers to a processing circuit, which may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated or group) and a memory that executes one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functions. For example, a module may be configured to stop charging and / or otherwise isolate one or more batteries of the battery pack of the vehicle 100 via software, hardware, and / or firmware.

[0098] The processing device 602 may also be configured to communicate with one or more external devices 616, such as a keyboard, a pointing device, and / or any device that enables the processing device 602 to communicate with one or more other computing devices (e.g., a network card, a modem, a vehicle ECU, etc.). Communication with various devices may occur via input / output (I / O) interfaces 618 and 620.

[0099] The processing device 602 may also communicate with one or more networks 622, such as a local area network (LAN), a general wide area network (WAN), a bus network, and / or a public network (e.g., the Internet) via a network adapter 624. In some embodiments, the network adapter 624 is or includes an optical network adapter for communicating over an optical network. It should be understood that, although not shown, other hardware and / or software components may be used in conjunction with the computer system 600. Examples include, but are not limited to, microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, and data archival storage systems, among others.

[0100] The terms "one" and "an" do not indicate a limitation of quantity, but rather indicate the presence of at least one of the referenced item. Unless the context clearly indicates otherwise, the term "or" means "and / or". References to "aspects" throughout the specification mean that a particular element (e.g., a 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 the various aspects.

[0101] 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.

[0102] Unless otherwise indicated herein, all test standards are the most current standards in effect as of the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the test standards appear.

[0103] 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.

[0104] 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 its scope. In addition, many modifications may be made to adapt specific circumstances or materials to the teachings of the disclosure without departing from the basic 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 method for heat-triggered adhesive release for battery maintenance, the method comprising: receiving a battery pack including an adhesive layer at an interface between the cooling plate and the component; directing a heating fluid through the enclosed volume of the cooling plate; measuring a temperature of the adhesive layer; as well as In response to determining that the temperature has reached the target temperature, a load is applied to the component until the component is removed.

2. The method according to claim 1, wherein: The adhesive comprises a material having a known bond strength as a function of temperature.

3. The method according to claim 1, wherein: Directing the heating fluid through the enclosed volume causes convective heat transfer from the heating fluid to the adhesive layer. 4 . The method of claim 1 , wherein applying the load to the component comprises applying one or more of a peel load, a shear load, and a tensile load to the component until cohesive failure or adhesive failure of the adhesive layer.

5. The method according to claim 1, wherein: The enclosed volume includes one or more fluid flow channels for circulating the heating fluid, a fluid inlet, and a fluid outlet.

6. The method according to claim 1, further comprising: measuring the temperature of the component; as well as In response to the temperature of the component being within a predetermined threshold of a thermal limit, one or more of a flow rate and a temperature of the heating fluid is reduced. 7 . The method of claim 1 , further comprising performing preparatory maintenance including disassembly prior to directing the heating fluid through the enclosed volume of the cooling plate.

8. The method of claim 1, further comprising replacing the removed component with a new component.

9. The method of claim 1, wherein the adhesive comprises a material having a known bond strength as a function of temperature, and wherein the target temperature is determined to achieve a target bond strength.

10. The method according to claim 9, wherein: Applying a load to the component includes applying a load sufficient to overcome the target bond strength.

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