ADHESIVE VENT PAD FOR A BATTERY MODULE

[0001] This application claims priority from and the benefit of U.S. Provisional Application Ser. No. 62/100,001, filed Jan. 5, 2015, entitled “MECHANICAL AND ELECTRICAL ASPECTS OF LITHIUM ION BATTERY MODULE WITH VERTICAL AND HORIZONTAL CONFIGURATIONS,” which is hereby incorporated by reference in its entirety for all purposes.

[0002] The present disclosure relates generally to the field of batteries and battery modules. More specifically, the present disclosure relates to an adhesive vent pad for enabling venting from a battery module.

[0003] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0004] A vehicle that uses one or more battery systems for providing all or a portion of the motive power for the vehicle can be referred to as an xEV, where the term “xEV” is defined herein to include all of the following vehicles, or any variations or combinations thereof, that use electric power for all or a portion of their vehicular motive force. For example, xEVs include electric vehicles (EVs) that utilize electric power for all motive force. As will be appreciated by those skilled in the art, hybrid electric vehicles (HEVs), also considered xEVs, combine an internal combustion engine propulsion system and a battery-powered electric propulsion system, such as 48 Volt (V) or 130V systems. The term HEV may include any variation of a hybrid electric vehicle. For example, full hybrid systems (FHEVs) may provide motive and other electrical power to the vehicle using one or more electric motors, using only an internal combustion engine, or using both. In contrast, mild hybrid systems (MHEVs) disable the internal combustion engine when the vehicle is idling and utilize a battery system to continue powering the air conditioning unit, radio, or other electronics, as well as to restart the engine when propulsion is desired. The mild hybrid system may also apply some level of power assist, during acceleration for example, to supplement the internal combustion engine. Mild hybrids are typically 96V to 130V and recover braking energy through a belt or crank integrated starter generator. Further, a micro-hybrid electric vehicle (mHEV) also uses a “Stop-Start” system similar to the mild hybrids, but the micro-hybrid systems of a mHEV may or may not supply power assist to the internal combustion engine and operates at a voltage below 60V. For the purposes of the present discussion, it should be noted that mHEVs typically do not technically use electric power provided directly to the crankshaft or transmission for any portion of the motive force of the vehicle, but an mHEV may still be considered as an xEV since it does use electric power to supplement a vehicle's power needs when the vehicle is idling with internal combustion engine disabled and recovers braking energy through an integrated starter generator. In addition, a plug-in electric vehicle (PEV) is any vehicle that can be charged from an external source of electricity, such as wall sockets, and the energy stored in the rechargeable battery packs drives or contributes to drive the wheels. PEVs are a subcategory of EVs that include all-electric or battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and electric vehicle conversions of hybrid electric vehicles and conventional internal combustion engine vehicles.

[0005] xEVs as described above may provide a number of advantages as compared to more traditional gas-powered vehicles using only internal combustion engines and traditional electrical systems, which are typically 12V systems powered by a lead acid battery. For example, xEVs may produce fewer undesirable emission products and may exhibit greater fuel efficiency as compared to traditional internal combustion vehicles and, in some cases, such xEVs may eliminate the use of gasoline entirely, as is the case of certain types of EVs or PEVs.

[0006] As technology continues to evolve, there is a need to provide improved power sources, particularly battery modules, for such vehicles. For example, in traditional configurations, battery modules may include a vent mechanism for venting gases from an inside of the battery module. The vent mechanism may enable venting in response to a pressure increase in the inside of the battery module (e.g., a pressure increase exceeding a venting pressure threshold of the battery module). Unfortunately, some traditional venting mechanisms for battery modules may be expensive, which drives up the cost of the battery module. Further, some traditional venting mechanisms may be limited to coarse calibration of the venting pressure threshold. Accordingly, it is now recognized that improved (e.g., more accurate, economic, and predictable) venting mechanisms for battery modules are desired.

[0007] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

[0008] The present disclosure relates to a battery module having a vent path with an exit port. The battery module also includes a vent pad disposed within the vent path and blocking at least a portion of the exit port, coupled to a boundary surface of the exit port via an adhesive layer between the vent pad and the boundary surface, and configured to enable venting through the exit port by separating from the boundary surface along the adhesive layer in response to a pressure against the vent pad exceeding a venting pressure threshold of the battery module.

[0009] The present disclosure also relates a housing of a battery module, where the housing includes a cover disposed over an opening in the housing, a vent path having an exit port disposed through a wall of the cover, and a vent pad blocking the exit port, coupled to a surface of the wall of the cover via an adhesive layer between the vent pad and the surface of the wall, and configured to enable venting through the exit port in response to a pressure within the vent path and against the vent pad exceeding a pressure threshold of the battery module.

[0010] The present disclosure also relates to a battery module having a vent path with an exit port. The battery module also includes a vent pad coupled to a first surface of the battery module through which the exit port extends and disposed over the vent opening. Further, the battery module includes a sharp edge facing the vent pad a first distance from a resting position of the vent pad, wherein the vent pad is configured to deflect from the resting position at least the first distance in response to a pressure within the vent path and against the vent pad exceeding a venting pressure threshold of the battery module, such that the sharp edge contacts and opens the vent pad to enable venting through the vent opening.

[0023] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0024] The battery systems described herein may be used to provide power to various types of electric vehicles (xEVs) and other high voltage energy storage/expending applications (e.g., electrical grid power storage systems). Such battery systems may include one or more battery modules, each battery module having a number of battery cells (e.g., lithium-ion (Li-ion) electrochemical cells) arranged and electrically interconnected to provide particular voltages and/or currents useful to power, for example, one or more components of an xEV. As another example, battery modules in accordance with present embodiments may be incorporated with or provide power to stationary power systems (e.g., non-automotive systems).

[0025] In accordance with embodiments of the present disclosure, the battery module may include a housing (e.g., plastic housing) configured to retain electrochemical cells (e.g., prismatic lithium-ion [Li-ion] electrochemical cells) within an inside of the housing. The housing may include features that seal the inside of the housing from an external environment outside of the housing. The housing may also include a vent path configured to enable gases to vent from the housing if an internal pressure within the inside of the housing exceeds a venting pressure threshold of the battery module. Specifically, the vent path may include an exit port having a vent opening. A vent pad (e.g., vent label, vent patch, adhesive vent label) may be disposed over the vent opening and coupled to the exit port (e.g., to a surface of the exit port at least partially defining the vent path) via an adhesive layer. For example, the adhesive layer may be disposed on the vent pad, and the adhesive layer of the vent pad may be pressed into the exit port (e.g., to the surface of the exit port at least partially defining the vent path) with the vent pad disposed over the vent opening.

[0026] During operation of the battery module, the electrochemical cells may thermally expand, causing the pressure on the inside of the housing to increase. Additionally or alternatively, gases may vent from the individual electrochemical cells into the inside of the housing, thereby causing the pressure on the inside of the housing to increase. The vent pad (and/or other features of the battery module) may be specifically calibrated to enable venting of the gases at a venting pressure threshold. For example, a material or texture of the housing, the vent pad, and/or the adhesive layer may be selected to enable venting of the gases at the venting pressure threshold. Additionally or alternatively, a specific pull-off strength of the adhesive layer (which may correspond directly or indirectly to the material or the texture of the adhesive layer) may be selected to enable venting of the gases at the venting pressure threshold. Further still, a thickness and/or a cross-sectional area of the vent pad, the vent opening, and/or the adhesive layer may be selected to enable venting of the gases at the venting pressure threshold. These and other features of the vent pad will be described in detail with reference to the figures below.

[0027] To help illustrate, FIG. 1 is a perspective view of an embodiment of a vehicle 10, which may utilize a regenerative braking system. Although the following discussion is presented in relation to vehicles with regenerative braking systems, the techniques described herein are adaptable to other vehicles that capture/store electrical energy with a battery, which may include electric-powered and gas-powered vehicles.

[0028] As discussed above, it would be desirable for a battery system 12 to be largely compatible with traditional vehicle designs. Accordingly, the battery system 12 may be placed in a location in the vehicle 10 that would have housed a traditional battery system. For example, as illustrated, the vehicle 10 may include the battery system 12 positioned similarly to a lead-acid battery of a typical combustion-engine vehicle (e.g., under the hood of the vehicle 10). Furthermore, as will be described in more detail below, the battery system 12 may be positioned to facilitate managing temperature of the battery system 12. For example, in some embodiments, positioning a battery system 12 under the hood of the vehicle 10 may enable an air duct to channel airflow over the battery system 12 and cool the battery system 12.

[0029] A more detailed view of the battery system 12 is described in FIG. 2. As depicted, the battery system 12 includes an energy storage component 13 coupled to an ignition system 14, an alternator 15, a vehicle console 16, and optionally to an electric motor 17. Generally, the energy storage component 13 may capture/store electrical energy generated in the vehicle 10 and output electrical energy to power electrical devices in the vehicle 10.

[0030] In other words, the battery system 12 may supply power to components of the vehicle's electrical system, which may include radiator cooling fans, climate control systems, electric power steering systems, active suspension systems, auto park systems, electric oil pumps, electric super/turbochargers, electric water pumps, heated windscreen/defrosters, window lift motors, vanity lights, tire pressure monitoring systems, sunroof motor controls, power seats, alarm systems, infotainment systems, navigation features, lane departure warning systems, electric parking brakes, external lights, or any combination thereof. Illustratively, in the depicted embodiment, the energy storage component 13 supplies power to the vehicle console 16 and the ignition system 14, which may be used to start (e.g., crank) the internal combustion engine 18.

[0031] Additionally, the energy storage component 13 may capture electrical energy generated by the alternator 15 and/or the electric motor 17. In some embodiments, the alternator 15 may generate electrical energy while the internal combustion engine 18 is running More specifically, the alternator 15 may convert the mechanical energy produced by the rotation of the internal combustion engine 18 into electrical energy. Additionally or alternatively, when the vehicle 10 includes an electric motor 17, the electric motor 17 may generate electrical energy by converting mechanical energy produced by the movement of the vehicle 10 (e.g., rotation of the wheels) into electrical energy. Thus, in some embodiments, the energy storage component 13 may capture electrical energy generated by the alternator 15 and/or the electric motor 17 during regenerative braking. As such, the alternator 15 and/or the electric motor 17 are generally referred to herein as a regenerative braking system.

[0032] To facilitate capturing and supplying electric energy, the energy storage component 13 may be electrically coupled to the vehicle's electric system via a bus 19. For example, the bus 19 may enable the energy storage component 13 to receive electrical energy generated by the alternator 15 and/or the electric motor 17. Additionally, the bus 19 may enable the energy storage component 13 to output electrical energy to the ignition system 14 and/or the vehicle console 16. Accordingly, when a 12 volt battery system 12 is used, the bus 19 may carry electrical power typically between 8-18 volts.

[0033] Additionally, as depicted, the energy storage component 13 may include multiple battery modules. For example, in the depicted embodiment, the energy storage component 13 includes a lithium ion (e.g., a first) battery module 20 in accordance with present embodiments, and a lead-acid (e.g., a second) battery module 22, where each battery module 20, 22 includes one or more battery cells. In other embodiments, the energy storage component 13 may include any number of battery modules. Additionally, although the lithium ion battery module 20 and lead-acid battery module 22 are depicted adjacent to one another, they may be positioned in different areas around the vehicle. For example, the lead-acid battery module 22 may be positioned in or about the interior of the vehicle 10 while the lithium ion battery module 20 may be positioned under the hood of the vehicle 10.

[0034] In some embodiments, the energy storage component 13 may include multiple battery modules to utilize multiple different battery chemistries. For example, when the lithium ion battery module 20 is used, performance of the battery system 12 may be improved since the lithium ion battery chemistry generally has a higher coulombic efficiency and/or a higher power charge acceptance rate (e.g., higher maximum charge current or charge voltage) than the lead-acid battery chemistry. As such, the capture, storage, and/or distribution efficiency of the battery system 12 may be improved.

[0035] To facilitate controlling the capturing and storing of electrical energy, the battery system 12 may additionally include a control module 24. More specifically, the control module 24 may control operations of components in the battery system 12, such as relays (e.g., switches) within energy storage component 13, the alternator 15, and/or the electric motor 17. For example, the control module 24 may regulate amount of electrical energy captured/supplied by each battery module 20 or 22 (e.g., to de-rate and re-rate the battery system 12), perform load balancing between the battery modules 20 and 22, determine a state of charge of each battery module 20 or 22, determine temperature of each battery module 20 or 22, control voltage output by the alternator 15 and/or the electric motor 17, and the like.

[0036] Accordingly, the control unit 24 may include one or more processor 26 and one or more memory 28. More specifically, the one or more processor 26 may include one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more general purpose processors, or any combination thereof. Additionally, the one or more memory 28 may include volatile memory, such as random access memory (RAM), and/or non-volatile memory, such as read-only memory (ROM), optical drives, hard disc drives, or solid-state drives. In some embodiments, the control unit 24 may include portions of a vehicle control unit (VCU) and/or a separate battery control module.

[0037] An overhead exploded perspective view of an embodiment of the battery module 20 for use in the vehicle 10 of FIG. 2 is shown in FIG. 3. In the illustrated embodiment, the battery module 20 (e.g., lithium ion [Li-ion] battery module) includes a housing 30 and electrochemical cells 32 disposed inside the housing 30. In the illustrated embodiment, six prismatic lithium-ion (Li-ion) electrochemical cells 32 are disposed in two stacks 34 within the housing 30, three electrochemical cells 32 in each stack 34. However, in other embodiments, the battery module 20 may include any number of electrochemical cells 32 (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, or more electrochemical cells), any type of electrochemical cell 32 (e.g., Li-ion, lithium polymer, lead-acid, nickel cadmium, or nickel metal hydride, prismatic, and/or cylindrical), and any arrangement of the electrochemical cells 32 (e.g., stacked, separated, or compartmentalized).

[0038] As shown, the electrochemical cells 32 may include terminals 36 extending upwardly (e.g., in direction 37) from terminal ends 39 of the electrochemical cells 32. Accordingly, the terminals 36 may extend into an opening 38 disposed in an upper side 40 or face of the housing 30. For example, the electrochemical cells 32 may be inserted into the housing 30 through the opening 38 in the upper side 40, and positioned within the housing 30 such that the terminals 36 of the electrochemical cells 32 are disposed in the opening 38. A bus bar carrier 42 may be disposed into the opening 38 and may retain bus bars 44 disposed thereon, where the bus bars 44 are configured to interface with the terminals 36 of the electrochemical cells 32. For example, the bus bars 44 may interface with the terminals 36 to electrically couple adjacent electrochemical cells 32 together. Depending on the embodiment, the bus bars 44 may couple the electrochemical cells 32 in series, in parallel, or some of the electrochemical cells 32 in series and some of the electrochemical cells 32 in parallel. Further, certain of the bus bars 44 may be configured to electrically couple the electrically interconnected group of electrochemical cells 32 with major terminals 46 of the battery module 20, where the major terminals 46 are configured to be coupled to a load (e.g., component(s) of the vehicle 10) to power the load. The electrochemical cells 32 also include vents 49 on the terminal ends 39 of the electrochemical cells 32 and configured to enable gases from within the electrochemical cells 32 to vent into the inside of the housing 30 in certain operating conditions (e.g., if a pressure within one or more individual electrochemical cell 32 exceeds a cell venting pressure threshold of the corresponding one or more individual electrochemical cells 32).

[0039] In accordance with the present disclosure, the housing 30 of the battery module 20 includes one or more covers configured to seal the housing 30. For example, the housing 30 may include a lateral cover 50 that fits over a lateral side 52 of the housing 30, where the lateral side 52 of the housing 30 retains, e.g., a printed circuit board (PCB) 52 and other electrical components of the battery module 20. An upper cover 54 may be disposed over the upper side 40 of the housing 30 (and over the bus bar carrier 42) to seal the upper side 40 of the housing 30. The upper cover 54 of the housing 30 may include a handle 56 embedded within the upper cover 54 and configured to facilitate transportation of the battery module 20 from one place to another. Further, the upper cover 54 may include one or more chambers 58 configured to at least partially define a vent path of the battery module 20. Further still, the upper cover 54 may include a vent spout 60 of the vent path through which gases or fluids may vent if an internal pressure within the housing 30 exceeds a venting pressure threshold of the battery module 20.

[0040] For example, an overhead perspective view of an embodiment of the battery module 20 of FIG. 3 is shown in FIG. 4, where the chambers 58 and the vent spout 60 of the upper cover 54 are illustrated transparently for clarity. FIG. 4 also includes a cutaway portion showing one of the electrochemical cells 32 disposed inside of the housing 30. Gases may vent from the electrochemical cells 32 into at least the chambers 58 of the upper cover 54 of the housing 30, where the chambers 58 define at least a portion of a vent path of the battery module 20. The vent path may also include an exit port 70 and the spout 60 (e.g., vent spout), where the exit port 70 extends through the spout 60. For example, in the illustrated embodiment, the exit port 70 extends through a wall 72 of one of the chambers 58 of the upper cover 54 (e.g., the wall 72 of the chamber 58 from which the spout 60 extends) and through the spout 60. It should be noted that, in another embodiment, the vent path may not include the spout 60, and the exit port 70 may only extend through the wall 72 of the chamber 58.

[0041] In accordance with present embodiments, a vent pad 76 (e.g., vent patch, vent label, adhesive vent label) is disposed over the exit port 70 to seal the exit port 70 from the inside of the housing 30 (e.g., to seal the exit port 70 from the chambers 58). The vent pad 76 may be coupled to the wall 72 of the chamber 58 (e.g., an inner surface of the wall 72) via an adhesive layer. In other embodiments, the vent pad 76 may be coupled, via the adhesive layer, to other surfaces adjacent a perimeter of the exit port 70, such as an outer surface of the wall 72 of the chamber 58 or to a surface of the spout 60. The adhesive layer may be initially disposed (e.g., before or during coupling of the vent pad 76 and the wall 72 of the chamber 58) on the vent pad 76, on the inner surface of the wall 72 of the chamber 58 (e.g., along a perimeter of the exit port 70), or both.

[0042] In general, the vent pad 76 is configured to block contaminants or objects outside of the battery module 20 from entering the housing 30, and to block gases from exiting the housing 30 through the exit port 70, unless an internal pressure within the vent path (e.g., within the chamber 58) and against the vent pad 76 exceeds a venting pressure threshold of the battery module 20 (e.g., of the vent pad 76 of the battery module 20). The venting pressure threshold may be calibrated by selecting or employing various characteristics of the vent pad 76, the exit port 70, the inner surface of the wall 72 to which the vent pad 76 is coupled (or some other surface to which the vent pad 76 is coupled, such as the outer surface of the wall 72 or a surface of the spout 60), the adhesive layer, and/or other features of the battery module 20. For example, a surface area of the vent pad 76 and/or the adhesive layer, and/or a wetted surface area of the vent pad 76 (e.g., where “wetted surface area” refers to the surface area of the vent pad 76 exposed to the exit port 70) may be determined and employed to provide a particular venting pressure threshold. Further, a thickness of the vent pad 76 and/or the adhesive layer may be determined and employed to provide a particular venting pressure threshold. Additionally or alternatively, a material or texture of the vent pad 76, the adhesive layer, and/or the wall 72 or other surface on which the vent pad 76 is disposed may be determined and employed to provide a particular venting pressure threshold. Further still, a pull-off strength of the adhesive layer may be determined and employed to provide a particular venting pressure threshold, although it should be noted that the pull-off strength of the adhesive layer may be at least in part a function of other calibration characteristics described above. For example, the materials and/or textures of the vent pad 76 and the surface to which the vent pad 76 is coupled may establish a particular bond strength. It should also be noted that the disclosed vent path and venting features (e.g., the exit port 70, the wall 72, the vent pad 76, the adhesive layer, the vent spout 60) may be included on the upper cover 54, or on or proximate to any other suitable portion of the housing 30. These and other features will be described in detail below with reference to the figures.

[0043] FIG. 5 is an overhead perspective view of an embodiment of the upper cover 54 for use in the battery module 20 of FIG. 3. The upper cover 54, for clarity, is rendered transparently in the illustrated embodiment. As shown, the chambers 58 of the upper cover 54 define at least a portion of a vent path of the battery module 20. In other words, the chambers 58 may receive vented gases until a pressure within the chambers 58 (e.g., within the vent path) and against the vent pad 76 exceeds a venting pressure threshold of the battery module 20. For example, the vent pad 76 disposed over the exit port 70 and coupled to the wall 72 (e.g., to the inner surface of the wall 72) via the adhesive layer may be exposed to at least one of the chambers 58 such that gases within the chamber 58 (e.g., within the vent path) press against the vent pad 76. If the pressure against the vent pad 76 (e.g., within the chamber(s) 58 of the vent path) exceeds the venting pressure threshold of the battery module 20, the vent pad 76 may enable venting through the exit port 70. Specifically, the vent pad 76 may be configured such that a surface area of the vent pad 76, a wetted surface area of the vent pad 76 (e.g., exposed to the exit port 70), a strength of the adhesive layer, a surface area of the vent pad 76 coupled to the inner surface of the wall 72 (or coupled to some other boundary or perimeter about the exit port 70), a nature (e.g., flexibility, porosity) of the material forming the vent pad 76, etc., operate together such that the internal pressure exceeding the venting pressure threshold of the battery module 20 may enable the vent pad 76 to pull away from the boundary or perimeter (e.g., the inner surface of the wall 72 of the chamber 58) to which the vent pad 76 is adhesively coupled, thereby exposing the exit port 70 and the chamber(s) 58 (e.g., of the vent path) to the environment 80. The gases vent through the exit port 70 that, in the illustrated embodiment, extends through the wall 72 and through the spout 60 (e.g., vent spout). In general, the spout 60 enables the gases to vent to an environment 80 external to the battery module 20, while also protecting the vent pad 76 from being torn via objects external to the housing 30 of the battery module 20.

[0044] It should be noted that, in accordance with present embodiments, the vent pad 76 is configured to enable venting by, in response to a pressure against the vent pad 76 exceeding the venting pressure threshold of the battery module 20, pulling away from the perimeter of the exit port 70 to which the vent pad 76 is adhesively coupled along the adhesive layer. However, in some embodiments, the vent pad 76 may be configured with redundancy measures in the event that the adhesive layer does not enable the vent pad 76 to pull away from the boundary of the exit port 70 to which the vent pad 76 is coupled. For example, the vent pad 76 may be configured to tear across a middle region of the vent pad 76 in response to an internal pressure of the battery module 20 (and against the vent pad 76) exceeding a secondary venting pressure threshold, which is generally greater than the venting pressure threshold.

[0045] Further, it should be noted that any calibration features of the vent pad 76, the adhesive layer, the exit port 70, the boundary or perimeter of the exit port 70 to which the vent pad 76 is coupled, or any other calibration features of the battery module 20 described herein with reference to calibrating the venting pressure threshold, may also be determined and employed to calibrate the secondary venting pressure threshold. Indeed, in some embodiments, certain of the calibration features may be determined and employed to enable the venting pressure threshold, and certain (other or the same) calibration features may be determined and employed to enable the secondary venting pressure threshold.

[0046] Further still, in some embodiments, the vent pad 76 may be configured to tear first (e.g., in response to the pressure against the vent pad 76 exceeding the venting pressure threshold), and pull away from the boundary or perimeter surface of the exit port 70 in the event the vent pad 76 does not tear (e.g., in response to the pressure against the vent pad 76 exceeding the secondary pressure threshold). It should also be noted that, in some embodiments, the vent pad 76 may be configured only to tear and to not pull away from the boundary surface of the exit port 70 along the adhesive layer 82.

[0047] FIG. 6 is a bottom perspective view of an embodiment of the cover 54 for use in the battery module 20 of FIG. 3. In the illustrated embodiment, the vent pad 76 includes a circular cross-sectional shape, although other suitable shapes in accordance with the present disclosure may be included. The vent pad 76 is disposed over the exit port 70, which also includes a circular cross-sectional shape, although other suitable shapes in accordance with the present disclosure may be included. As shown, an annular portion of the vent pad 76 overlaps with an annular portion of the inner surface of the wall 72 of the chamber 58 in which the exit port 70 is disposed (e.g., the perimeter or boundary surface around the exit port 70). In accordance with present embodiments, the overlapping annular portions of the vent pad 76 and the perimeter or boundary surface of the exit port 70 may include an adhesive layer 82 disposed therebetween. The adhesive layer 82 may be initially disposed on the vent pad 76, on the perimeter of the exit port 70 (e.g., on the inner surface of the wall 72), or both, and may operate to retain the vent pad 76 over the exit port 70. In some embodiments, the vent pad 76 may pull away from the wall 72 along the adhesive layer 82 if the pressure against the vent pad 76 (and, thus, within the vent path, or within the chamber(s) 58) exceeds the venting pressure threshold of the battery module 20. For example, the vent pad 76 and the adhesive layer 82 may separate from the wall 72 to enable gases to vent through the exit port 70. As previously described, the vent pad 76 (and/or other venting features) may be configured such that the vent pad 76 tears through a middle region if the internal pressure within the chamber 58 (and against the vent pad 76) exceeds the secondary venting pressure threshold of the battery module 20. The secondary venting pressure threshold is greater than the venting pressure threshold, where the venting pressure threshold, as previously described, is calibrated to enable the vent pad 76 to pull away from the wall 72 along the adhesive layer 82.

[0048] A cross-sectional view of an embodiment of the vent pad 76 disposed in a portion of the vent path is shown in FIG. 7. As previously described, an outer annular portion 90 of the vent pad 76 may overlap with an annular portion 92 of perimeter or boundary surface of the exit port 70 (e.g., along an inner surface 97 of the wall 72 of the chamber 58 and around the exit port 70). The vent pad 76 may be coupled at the outer annular portion 90 to the annular portion 92 of the inner surface 97 of the wall 72 via the adhesive layer 82. As shown, the adhesive layer 82 may substantially cover the entire outer annular portion 90 of the vent pad 76 that overlaps with the annular portion 92 of the inner surface 97 of the wall 72.

[0049] It should be noted that the vent pad 76 may be coupled to a different surface of the upper cover 54, or a different surface of the battery module 20. For example, the vent pad 76 may be coupled, via the adhesive layer 82, to an end surface 99 of the spout 60. Further, in embodiments not having the spout 60, the vent pad 76 may be coupled, via the adhesive layer 82, to an outer surface 101 of the wall 70 opposite to the inner surface 97. In general, the vent pad 76 may be coupled to a surface proximate an entrance 102 to the exit port 70 or proximate to an exit 105 of the exit port 70. As shown, the entrance 102 in the illustrated embodiment is even with the inner surface 97 of the wall 72 (e.g., in direction 107), and the exit 105 is even with an end of the spout 60 (e.g., in direction 107). However, in embodiments not having the spout 60, the exit 105 may be even with the outer surface 101 of the wall 72 (e.g., in direction 107) or even with some other surface of the upper cover 54 or battery module 20.

[0050] In other embodiments, the adhesive layer 82 may only be applied between a portion of the outer annular portion 90 of the vent pad 76 and the annular portion 92 of the inner wall 72. Indeed, such controlled application may be used for calibration purposes. For example, more or less surface area may include adhesive to increase or lessen the venting pressure threshold (e.g. relief threshold), respectively. A front view of an embodiment of the vent pad 76 covering the exit port 70 is shown in FIG. 8. In the illustrated embodiment, the adhesive layer 82 is arcuate with a radial width 100 equal to that of the overlapping annular portions 90, 92 of the vent pad 76 and the boundary surface of the exit port 70, respectively. However, the radial width 100 of the adhesive layer 82 may be smaller or larger than that of the overlapping annular portions 90, 92 based on calibration preference. The adhesive layer 82 may additionally (or alternatively) extend less than 360 degrees around the exit port 70. For example, the adhesive layer 82 may include multiple arcuate strips 104 (e.g., two or more arcuate strips 104) of less than 360 degrees arranged about the exit port 70 and between the overlapping annular portions 90, 92 of the vent pad 76 and the boundary surface of the exit port 70 (e.g., the wall 72 of the chamber 58), respectively. Further, as shown in the illustrated embodiment, the vent pad 76 may include a kiss-cut 113 or score grooved into the vent pad 76 to facilitate tearing of the vent pad 76 in response to the internal pressure within the vent path exceeding the secondary venting pressure threshold of the battery module 20, as previously described.

[0051] In general, the vent pad 76, the adhesive layer 82, the wall 72 (or other boundary or perimeter surface of the exit port 70), and the exit port 70 may be designed to calibrate the venting pressure threshold, in accordance with present embodiments, such that venting through the exit port 70 is enabled when an internal pressure within the vent path (e.g., within the chamber 58) and against the vent pad 76 exceeds the venting pressure threshold. For example, a particular surface texture of the boundary surface of the exit port 70, of the vent pad 76, of the adhesive layer 82, or a combination thereof may be specifically included to calibrate the venting pressure threshold of the battery module 20. Further, a particular thickness of the adhesive layer 82, thickness of the vent pad 76, thickness of the wall 72, surface area of the adhesive layer 82, wetted surface area of the vent pad 76, surface area of the vent pad 76, overlapping surface areas of the vent pad 76 and the boundary surface to the exit port 70, or a combination thereof may be specifically included to calibrate the venting pressure threshold (and/or the secondary venting pressure threshold) of the battery module 20. Further still, a particular material of the adhesive layer 82, material of the vent pad 76, material of the boundary surface of the exit port 70, pull-off strength of the adhesive layer 82 (which may correspond with materials and/or textures of the vent pad 76, the adhesive layer 82, the boundary surface to the exit port 70, etc.), or a combination thereof may be specifically included to calibrate the venting pressure threshold (and/or the secondary venting pressure threshold) of the battery module 20. In embodiments including multiple strips 104 of the adhesive layer 82, a particular number of the strips 104, a number of arcuate degrees per strip 104, other characteristics (e.g., thickness) or a combination thereof may be specifically included to calibrate the venting pressure threshold of the battery module 20. Further, to enable venting through the exit port 70, the vent pad 76 may be designed to pull away from the surface to which the vent pad 76 is coupled via the adhesive layer 82 (e.g., the wall 72 of the exit port 70) along the adhesive layer 82. In some embodiments, as previously described, the vent pad 76 may be designed to tear through a middle region 103 of the vent pad 76. It should be noted that the vent pad 76 may flex to an extent, by design, before pulling away from the boundary surface of the exit port 70 (e.g., the boundary surface extending along the wall 72). Certain of the venting calibration features described above may be specifically included to determine the one or more of the pressure thresholds for various venting modes (e.g., pull-away mode or tear mode) of the vent pad 76.

[0052] It should be noted that, in accordance with present embodiments, the disclosed vent pad 76, exit port 70, adhesive layer 82, and vent path may be included in any suitable area of the battery module 20 or housing 30 of the battery module 20. The embodiments and corresponding descriptions of the venting features with respect to the upper cover 54 are non-limiting.

[0053] Further, it should be noted that, in other embodiments, additional features may be included that enable the vent pad 76 to allow venting through the exit port 70. For example, cross-sectional side views of embodiments of the vent path (e.g., having the vent pad 76 disposed therein) are shown in FIGS. 9 and 10. In the illustrated embodiments, a sharp edge 106 is disposed a first distance 120 from the vent pad 76. The distance 120 may be specifically determined and employed for calibrating the venting pressure threshold of the battery module 20. In the embodiment shown in FIG. 9, the sharp edge 106 extends from a surface 108 within the spout 60. In the embodiment shown in FIG. 10, the sharp edge 106 is disposed within a loosely arranged bubble 109 disposed on (e.g., coupled to) the vent pad 76. For example, the bubble 109 is coupled or connected to the vent pad 76 along a connecting edge of the bubble 109. A rise in pressure within the vent path (e.g., within the chamber 58 of, or proximate to, the exit port 70) and against the vent pad 76 may cause the vent pad 76 to deflect or flex outwardly (e.g., in direction 107, as indicated by deflection 111 in FIG. 9) toward the sharp edge 106. As the vent pad 76 flexes outwardly, the connecting edge of the bubble 109 remains fixed to the vent pad 76. Thus, the bubble 109 becomes more and more taut, until the sharp edge 106 contacts the vent pad 76. The amount of deflection 111, which may be a property of the material or elasticity of the vent pad 76, may be specifically determined and employed for calibration of the venting pressure threshold of the battery module 20. It should also be noted that the bubble 109 in FIG. 10 may be coupled to the vent pad 76 along the connecting edge while the bobble 109 is in a relaxed condition during normal operating conditions, and while the vent pad 76 may be in a taut condition. Thus, the vent pad 76 may deflect or flex outwardly (e.g., in direction 107) more so than the bubble 109 (which is fixed to the vent pad 76 along the connecting edge) as the bubble 109 becomes increasingly more taut, thereby enabling the sharp edge 106 coupled to the bubble 109 to contact and open the vent pad 76, enabling venting through the exit port 70). Further, it should be noted that, in embodiments including the sharp edge 106, the vent pad 76 may be coupled to the boundary surface of the exit port 70 (e.g., to the wall 72 of the chamber 58) via some other coupling mechanism. It should also be noted that the vent pad 76 may include the kiss-cut 113 shown in FIG. 8, and that the sharp edge 106 may contact the grooves of the kiss-cut 113 to open the vent pad 76. It should also be noted that any number of sharp edges 106 may be included to facilitate opening of the vent pad 76, and that locations of the one or more sharp edges 106 (e.g., proximate a center of the vent pad 76, a perimeter of the vent pad 76, or anywhere else along the vent pad 76) may be determined and employed to calibrate the venting pressure threshold of the battery module 20.

[0054] Turning now to FIG. 11, a schematic view of an embodiment of a portion of a vent path 120 for use in the battery module 20 of the vehicle 10 of FIG. 2 is shown. In the illustrated embodiment, the vent path 120 includes the exit port 70 extending through at least the spout 60 and the wall 72 (e.g., any wall of the battery module). In other embodiments, the vent path 120 may not include the spout 60. As shown, multiple vent pads 76 may be disposed in various locations along the vent path 120. For example, one vent pad 76 may be coupled to the wall 72 (via the adhesive layer 82) over the entrance 102 to the exit port 70. A different vent pad 76 may be coupled to the wall 72 (via the adhesive layer 82) on a different surface of the wall 72, such as exit surface 112 of the wall 72. Further, a different vent pad 76 may be disposed over an exit of the exit port 70 (e.g., coupled via the adhesive layer 82 to the end surface 99 of the spout 60. It should be noted that any combination of the illustrated vent pads 76 may be included, in accordance with present embodiments, including only one of the illustrated vent pads 76. Further, any of the aforementioned vent features (e.g., the sharp edge 106, the bubble 109, the kiss cut 113) may be included. As previously described, if the internal pressure within the battery module 20 and against any of the vent pads 76 exceeds the venting pressure threshold of, for example, the vent pad 76, the vent pad(s) 76 in question may enable venting through at least the portion of the exit port 70 sealed by the vent pad 76. It should be noted that the vent path 110 (e.g., the exit port 70, the vent pad 76 disposed in the vent path 110, the adhesive layer 82, and, depending on the embodiment, other features of the battery module 20) may be located in any suitable are of the battery module. Further, as previously described, the vent pad 76, the exit port 70, the adhesive layer 82, and other features of the battery module 20 may include characteristics specifically determined for calibrating the venting pressure threshold of the battery module 20, as discussed above.

[0055] One or more of the disclosed embodiments, alone or in combination, may provide one or more technical effects useful in the manufacture of battery modules, and portions of battery modules. In general, embodiments of the present disclosure include a vent path having an exit port and a vent pad disposed over the exit port. An adhesive layer is disposed between the vent pad and a boundary or perimeter surface of the exit port. In accordance with present embodiments, the vent pad, the exit port, the boundary or perimeter surface of the exit port, the adhesive layer, and/or other features or components of the battery module may be designed to calibrate a venting pressure threshold of the battery module. In other words, characteristics of the vent pad, the exit port, the boundary or perimeter surface of the exit port, the adhesive layer, and/or the other features or components of the battery module may be included such that the vent pad enables venting through the exit port if a pressure inside the vent path (and against the vent pad) exceeds the venting pressure threshold. This provides a tunable and economic vent control feature. Also, certain characteristics such as porosity and flexibility may be utilized for calibration. The technical effects and technical problems in the specification are exemplary and are not limiting. It should be noted that the embodiments described in the specification may have other technical effects and can solve other technical problems.

[0056] While only certain features and embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the disclosed subject matter. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.