Battery assembly with vents from battery containers with pressure surge covers that use electrical interlocks to detect thermal events

Abstract

Battery assembly (100) comprising: one or more electrochemical battery cells (102); a module housing (104) in which the one or more battery cells (102) are accommodated, wherein the module housing (104) has a wall with a fluid connection configured to that the gas generated by the one or more battery cells (102) is released through them; a pressure burst cap (118) movably mounted on the module housing (104) for selectively switching between a closed position in which the pressure burst cap (118) covers the fluid port, and an open position in which the pressure burst cap (118) at least partially releases the fluid connection; and an electrical interlock circuit (122) configured to be connectable to a controller (130) and comprising an electrical circuit line (124) attached to the pressure rupture cap (118) and the module housing (104), the electrical circuit line (124) maintaining the pressure rupture cap (118) in the closed position and configured to fail at a preset breaking force to generate an interrupt signal within the electrical interlock circuit (122) indicative of a thermal event; wherein the circuit line (124) is made as an electrical wire that is guided through the interior of the module housing (104) and extends into and through the pressure rupture cap (118).

Description

[0001] This description relates generally to electrochemical devices. In particular, aspects of this description relate to thermal management systems for detecting thermal runaway (TR) events in battery assemblies.

[0002] Today's production vehicles, such as the modern automobile, are originally equipped with a powertrain that propels the vehicle and supplies the vehicle's on-board electronics. In motor vehicles, for example, the powertrain typically consists of a prime mover that transmits drive torque to the vehicle's drive system (e.g., differential, axle shafts, cam modules, wheels, and so on) via an automatic or manual transmission. In the past, motor vehicles were powered by piston internal combustion engines because they were readily available, relatively inexpensive, lightweight, and highly efficient. These engines include compression-ignition (CI) diesel engines, spark-ignition (SI) gasoline engines, two-, four-, and six-stroke engines, and rotary engines, to name just a few.Hybrid electric and fully electric vehicles (collectively referred to as “electric vehicles”), on the other hand, use alternative energy sources to power the vehicle, thus minimizing or eliminating the dependence on a fossil fuel-based engine for traction power.

[0003] A fully electric vehicle (FEV)—colloquially referred to as an "electric car"—is an electric-powered vehicle configuration that completely eliminates the internal combustion engine and associated peripheral components of the propulsion system, instead utilizing a rechargeable energy storage system (RESS) and a traction motor for vehicle propulsion. The engine assembly, fuel supply, and exhaust system of an internal combustion engine vehicle are replaced in a battery-assisted FEV by one or more traction motors, rechargeable battery cells, and cooling and charging equipment. Hybrid electric vehicle (HEV) powertrains, on the other hand, utilize multiple traction power sources to propel the vehicle, typically an internal combustion engine in conjunction with a battery- or fuel-cell-powered traction motor.Because electric vehicles are capable of deriving their power from sources other than the engine, HEV engines can be fully or partially shut down while the vehicle is powered by the electric motor(s).

[0004] High-voltage electrical systems regulate the power transfer between the traction motors and the rechargeable battery packs that provide the energy required to operate many hybrid-electric and all-electric powertrains. To provide the power capacity and energy density required to propel a vehicle at desired speeds and ranges, modern traction battery packs combine multiple battery cells (e.g., 8-16+ cells / stack) into individual battery modules (e.g., 10-40+ modules / pack), electrically connected in series or parallel, and mounted on the vehicle chassis, for example, through a battery pack enclosure or carrier plate.On the battery side of the high-voltage grid, a DC-DC converter is electrically connected to the traction battery(ies) to boost the voltage supply to a main DC bus and a DC-DC inverter module (PIM). A high-frequency, large-capacity capacitor can be placed between the positive and negative terminals of the main DC bus to ensure electrical stability and store additional electrical energy. A dedicated electronic battery control module (EBCM), in conjunction with a powertrain control module (PCM) and the power electronics of each motor, regulates the operation of the battery pack(s) and traction motor(s).

[0005] The individual cells of a battery pack can generate a significant amount of heat during the pack's charge and discharge cycles. This cell heat is generated primarily through exothermic chemical reactions and losses due to activation energy, chemical transport, and resistance to ion migration. A series of exothermic and gas-forming reactions can occur in lithium-ion batteries as cell temperatures rise, placing the battery assembly into an unstable state. Such thermal processes, if left unchecked, can lead to an accelerated, heat-generating condition known as "thermal runaway," a condition in which the battery system is unable to return the internal battery components to normal operating temperatures. An integrated battery cooling system can be employed to prevent these undesirable overheating conditions in such battery packs.Active thermal management (ATM) systems, for example, use a central control unit or a dedicated control module to regulate the operation of a cooling circuit that circulates coolant through the heat-generating battery components. Indirect liquid cooling systems, a heat-transferring coolant circulates through a network of internal channels and tubes within the battery enclosure. In contrast, direct liquid cooling—or "liquid immersion cooling" (LIC)—systems immerse the battery cells in a directly conductive liquid dielectric.

[0006] DE 10 2020 004 558 A1 describes a device for detecting a pressure drop in the event of bursting elements in a battery housing with at least one cell module consisting of several individual battery cells. The device is characterized in that a current loop is provided which comprises a current conductor with at least one predetermined breaking point, wherein a cavity arranged in the housing is closed off from the interior volume of the housing by a movable cover, wherein the current conductor extends partially over the cover, and wherein the cavity is connected to the interior volume of the housing via a pressure equalization bore.

[0007] DE 10 2010 005 097 A1 describes a temperature-controlled battery cell arrangement comprising a plurality of individual battery cells, a support structure that surrounds each of the battery cells individually, at least partially, over a flat surface, and a temperature control medium that can be brought into thermal contact with the support structure. The battery cell arrangement is characterized in that the receiving structure has receiving pockets arranged in layers, each receiving pocket providing at least two flat pocket walls between which at least one battery cell can be inserted, and in that two adjacent receiving pockets are joined together in such a way that at least one through-channel through which the temperature control medium can flow is provided between the adjacent receiving pockets.

[0008] Presented are pressure burst covers with electrified locks for gas vents in battery containers, exemplary methods for manufacturing and using such pressure burst covers, and, in one application, electrically powered vehicles equipped with such locked pressure burst covers for detecting thermal events in lithium-class traction battery packs. For example, battery module housings or battery cell housings (collectively referred to as "battery containers") with liquid vents for the passive evacuation of gases generated in the battery are known. These gas vents are covered with rupture discs, plates, or other similarly suitable valve designs (collectively referred to as "caps" or "lids") that extend over the vents and, if desired, seal them liquid-tight.Each pressure rupture cover may have a one-piece, disc-shaped construction and be secured by one or more electrical leads of a low-voltage (LV) interlock circuit. The electrical lead(s) may extend through or over an exterior surface of the vent cover and may be electrically connected to a voltage measuring device integrated with or connected to a system controller. In one example, the electrical lead consists essentially of an electrically conductive wire fixedly attached to both the vent cover and the battery container, with the cover being movably attached to the container. Likewise, the pressure rupture cover may consist essentially of an electrically non-conductive disc or plate.

[0009] This design provides thermal runaway detection by using the integrated low-voltage interlock circuit lead(s) to monitor the displacement of the pressure relief valve. When a battery cell or module experiences thermal runaway, it can generate a large amount of heat and gas, which in turn causes pressure to build up within the battery container. When the resulting internal pressure reaches or exceeds a predefined burst pressure threshold, the interlock circuit leads partially fail or rupture. In doing so, the pressure burst cover can physically separate from the container to release the internal heat and gas pressure from the battery system. Disconnecting the interlock lead(s) in this manner also results in an open circuit in the TR detection system.A microcontroller can monitor the interlock circuit and use the opening of the circuit to indicate the onset of a thermal runaway. Rapid and accurate detection of a TR event allows the system to more quickly automate remedial actions to mitigate the effects of the thermal event.

[0010] Existing thermal runaway detection methods often rely on package-level architectures for sensor placement and control strategies. In contrast, the presented concepts utilize cell-level and / or module-level detection and control without the need to attach dedicated sensors and communication devices to each cell / module. Eliminating the placement of sensors and connectors on each cell / module in a battery system with dozens / hundreds of modules / cells helps reduce the number of system parts and costs, decrease manufacturing time and costs, and simplify the overall system design. Additional benefits include reduced battery system weight and volume and the associated savings in vehicle size and weight.In addition to reducing system complexity and vehicle weight, thermal management is also improved, increasing battery capacity, resulting in improved overall vehicle efficiency and a longer range.

[0011] The invention is defined by the independent claim.

[0012] This description relates to pressure rupture covers with electrified interlocks for gas vents of battery assemblies, including individual battery cell assemblies or individual battery module assemblies. A battery assembly according to the invention comprises a module housing in which one or more electrochemical battery cells are housed. The module housing includes at least one wall with a fluid port through which gases generated by the cells are vented. A pressure rupture cap is movably mounted on the module housing for selectively switching between a closed and an open position. In the closed position, the pressure rupture cap covers the fluid port. In the open position, however, the pressure rupture cap partially or completely exposes the port. The battery assembly also includes an electrical interlock circuit configured to be connectable to a controller.The electrical interlock circuit includes a circuit lead, the circuit lead being attached to a pressure rupture cap and the module housing. The circuit lead maintains the pressure rupture cap in the closed position and is configured to fail at a preset rupture force to generate an interrupt signal within the electrical interlock circuit indicating a thermal event. The circuit lead is constructed as an electrical wire routed through the interior of the module housing and extending into and through the pressure rupture cap.

[0013] The description refers to motor vehicles with lithium-class traction battery packs that use one of the pressure burst covers described here to detect the onset of a thermal event.As used herein, the terms “vehicle” and “motor vehicle” may be used interchangeably and synonymously to include any relevant vehicle platform, such as passenger vehicles (ICE, HEV, FEV, fuel cell, fully and semi-autonomous vehicles, and so on), commercial vehicles, industrial vehicles, tracked vehicles, off-road and all-terrain vehicles (ATVs), motorcycles, agricultural equipment, e-scooters, e-bikes, personal watercraft, aircraft, and so on. For non-automotive applications, the described concepts may be implemented for any logically relevant use, including stand-alone power plants and portable power units, photovoltaic systems, pumping systems, machine tools, server systems, and so on. Although not limited per se, the described concepts may be particularly advantageous for use with lithium-class prismatic traction batteries.

[0014] A motor vehicle comprises a vehicle body with a passenger compartment, a plurality of wheels attached to the vehicle body (for example, via corner modules coupled to a unibody or body-on-frame chassis), and other standard original equipment. In electric-powered vehicles, one or more electric traction motors operate alone (for example, in FEV powertrains) or in conjunction with an internal combustion engine (for example, in HEV powertrains) to selectively drive one or more of the wheels and propel the vehicle. A rechargeable traction battery pack is attached to the vehicle body, for example, via a housing or carrier mounted on the vehicle chassis, and is electrically connected to the traction motor, i.e., to transfer electrical power to it.

[0015] Continuing the previous discussion, the traction battery pack includes an electrical interlock circuit electrically connected to a fixed or remote controller and includes a network of circuit wires. The traction battery pack also includes a group of lithium-class battery cells, such as prismatic, can, or pouch battery cells. Each battery cell comprises a battery stack with one or more working electrode pairs, one or more separators, one or more insulators, and an ion-transferring electrolyte. Each battery stack is housed in a corresponding cell enclosure having a wall with a fluid port through which cell gases generated by the battery stack are vented.A pressure rupture cap is movably attached to each cell casing to transition from a closed position, where the pressure rupture cap covers the cell casing's fluid port, to an open position, where the pressure rupture cap exposes the fluid port. A circuit cable within the network of circuit cables movably attaches each pressure rupture cap to its cell casing. The circuit cable holds the pressure rupture cap in the closed position; when subjected to a minimal tensile / torsional rupture force caused by elevated pressures within the cell casing, the cable partially or completely fails. In doing so, the lead at least partially detaches the pressure rupture cap from the cell casing, causing the cap to transition to the open position. Simultaneously, the failed lead generates an open signal within the electrical interlock circuit, indicating a thermal runaway.

[0016] The description also relates to methods of manufacturing workflows, computer readable media (CRM) for operation, and control logic for using the described pressure rupture covers, battery assemblies, and / or vehicles, the description of which is useful in understanding the present battery assembly. In one example, a method of manufacturing a battery assembly is presented. This representative method comprises, in any order and in any combination with any of the options and features described above and below, manufacturing, assembling, receiving, or retrieving (collectively, "receiving") an electrochemical battery cell; receiving a battery container; placing the battery cell within the battery container, the battery container having a container wall with a liquid opening configured to evacuate gas generated by the cell therethrough;Placing a pressure rupture cap over the fluid opening such that the pressure rupture cap is capable of selectively transitioning from a closed position in which the pressure rupture cap covers the fluid opening to an open position in which the pressure rupture cap at least partially exposes the fluid opening; incorporating an electrical interlock circuit configured to be connectable to a controller and including a circuit lead; and attaching the circuit lead to the pressure rupture cap and the battery container, the circuit lead maintaining the pressure rupture cap in the closed position and being configured to fail at a preset rupture force, thereby generating an interrupt signal within the electrical interlock circuit indicative of a thermal event.

[0017] In one embodiment, the pressure rupture cap is movably attached to the battery container by the circuit lead such that the pressure rupture cap selectively moves from the closed to the open position upon circuit lead failure. Optional embodiments may utilize a separate mechanism for pivotally, slidably, or detachably attaching the pressure rupture cap to the battery container such that the circuit lead primarily serves to hold the cap closed and initiate an open circuit in response to the occurrence of a TR event. In another option, the circuit lead may deform, fracture, or completely break at the preset breaking force (collectively referred to as "failure"), causing all or part of the pressure rupture cap to physically detach from the battery container.

[0018] In one embodiment, a first side of the pressure rupture cap is attached to a first portion of the module housing by a first segment of the circuit line, and a second side of the pressure rupture cap is attached to a second portion of the module housing by a second segment of the circuit line.

[0019] In one embodiment, the circuit line consists of an electrical wire formed from an electrically conductive material. The circuit line is permanently attached to both the pressure rupture cap and the module housing.

[0020] If desired, the conduit may extend over the outer surfaces of both the pressure rupture cap and the battery container. Alternatively, the circuit conduit may be formed integrally with the cap or container, so that the conduit extends through the cap / container.

[0021] In one embodiment, the circuit conduit comprises a pin and sleeve connector, a pin and socket connector, and / or a single-pole connector that holds the pressure burst cap in the closed position and is configured to fail by opening at the preset burst force.

[0022] In all of the batteries, methods, and vehicles described, the pressure rupture cap may extend the entire length of the fluid port in the closed position, obscuring it. Alternatively, the pressure rupture cap may be substantially flush with the container wall and enclose the fluid port. In the closed position, the pressure rupture cap may seal the fluid port (for example, with a polymer gasket or sealing ring). However, when the cap is moved to the open position, the fluid port is exposed. The pressure rupture cap may be manufactured as a one-piece structure, made entirely or partially from a high-temperature, flame-resistant, and slow-burning polymer material.

[0023] In one embodiment, the circuit line maintains an electrical voltage across at least one branch of the electrical interlock circuit, which voltage is detectable by the controller. The interrupt signal can be generated by interrupting the electrical voltage across the electrical interlock circuit when the circuit line fails at the preset breaking force.

[0024] As previously mentioned, the battery unit may be a battery module or a battery cell. In a battery module application, the battery container may comprise a battery module casing, and the electrochemical battery cell may comprise a group of lithium-class battery cells. In a battery cell application, the battery container may comprise a battery cell casing, and the electrochemical battery cell may comprise a plurality of working electrodes, a separator, an insulator, and an electrolyte, all contained within the battery cell casing. Fig. 1 is a partially schematic side view of a motor vehicle having an electrified powertrain, a rechargeable traction battery pack, and a pack monitoring system for detecting a thermal incident in the traction battery pack. Fig. Figure 2 is an enlarged perspective view of a representative battery assembly in the form of a battery module with a battery case vent covered by a pressure rupture cap that utilizes an electrified interlock line to detect thermal events. Fig. 3A and Fig. 3B are schematic plan view illustrations of another representative battery assembly in the form of a prismatic lithium-class battery cell with a pressure rupture cap closed with an attached electrical locking cable ( Fig. 3A), and the pressure rupture disc, which is opened with the electrically isolated locking cable ( Fig. 3B).

[0025] For the purposes of this detailed description, unless expressly excluded: the singular includes the plural and vice versa; the words "and" and "or" apply in both the subjunctive and disjunctive moods; the words "each" and "all" mean "each and all"; and the words "including," "including," "comprising," "with," and the like each mean "including without limitation." Furthermore, words of approximation such as "approximately," "almost," "substantially," "generally," "about," and the like may be used herein to mean "at, near, or almost at," or "within 0-5% of," or "within acceptable manufacturing tolerances," or any logical combination thereof, for example.Finally, directional adjectives and adverbs such as "front", "rear", "inside", "outside", "starboard", "port", "vertical", "horizontal", "up", "down", "forward", "backward", "left", "right" and so on can refer to a motor vehicle, for example, the forward travel of a motor vehicle when the vehicle is operated on a horizontal driving surface.

[0026] With reference to the drawings, in which like reference numerals refer to like features in the several views, Fig. 1 illustrates a representative motor vehicle, generally designated 10, which is depicted here for discussion purposes as an electric sedan. The depicted motor vehicle 10—also referred to herein as a “motor vehicle” or “vehicle” for short—is merely an exemplary application with which new aspects of this description may be practiced. Likewise, the incorporation of the present concepts into an FEV powertrain should be understood as a non-limiting implementation of the described features. It is understood that aspects and features of this description may be applied to other powertrain architectures, incorporated into any logically relevant type of vehicle, and utilized for both automotive and non-automotive applications. Furthermore, only selected components of the motor vehicles, battery assemblies, and pressure rupture caps are shown and described in detail herein.Nevertheless, the vehicles, assemblies, and caps described below may include numerous additional and alternative features and other available peripheral components to perform the various methods and functions of this description.

[0027] The representative vehicle 10 of Fig. 1 is originally equipped with a vehicle telecommunications and information unit ("telematics") 14 that communicates wirelessly, for example, via cell towers, base stations, mobile switching centers, satellite services, and so forth, with a remote or "off-board" cloud computing host service 24 (for example, OnStar®). Some of the other vehicle hardware components 16 that are included in Fig. 1 include, by way of non-limiting examples, an electronic video display device 18, a microphone 28, audio speakers 30, and various user input controls 32 (e.g., buttons, knobs, touchscreens, joysticks, pedals, and so on). These hardware components 16 may function as a human-machine interface (HMI), allowing the user to communicate with the telematics unit 14 and other components located within or remote from the vehicle 10. A microphone 28, for example, allows occupants to input verbal or other audible commands. Conversely, a speaker 30 provides audible output to a vehicle occupant and may be either a standalone speaker designed for use with the telematics unit 14 or may be part of an audio system 22.The audio system 22 is connected to a network connection interface 34 and an audio bus 20 to receive analog information and reproduce it as sound through one or more speaker components.

[0028] Communicatively coupled to the telematics unit 14 is a network connection interface 34, suitable examples of which include twisted pair / fiber optic Ethernet switches, parallel / serial communication buses, local area network (LAN) interfaces, controller area network (CAN) interfaces, and the like. The network connection interface 34 enables the vehicle hardware 16 to send and receive signals with each other and with various systems both onboard and external to the vehicle body 12. In this way, the vehicle 10 can perform various vehicle functions, such as modulating powertrain power, activating a braking system, regulating the charging and discharging of a vehicle battery, and other automatic functions.For example, the telematics unit 14 may exchange signals with a powertrain control module (PCM) 52, an advanced driver assistance system (ADAS) module 54, an electronic battery control module (EBCM) 56, an steering control module (SCM) 58, a brake system control module (BSCM) 60, and various other vehicle ECUs such as a transmission control module (TCM), an engine control module (ECM), and so on.

[0029] With further reference to Fig. 1, the telematics unit 14 is an in-vehicle computing device that provides a mix of services both individually and through its communication with other networked devices. This telematics unit 14 generally consists of one or more processors 40, each of which may be embodied as a discrete microprocessor, an application-specific integrated circuit (ASIC), or a dedicated control module. The vehicle 10 may provide centralized vehicle control via a central processing unit (CPU) 36 operatively coupled to a real-time clock (RTC) 42 and one or more electronic storage devices 38, each of which may take the form of a CD-ROM, a magnetic disk, an integrated circuit (IC), solid-state drive (SSD), hard disk drive (HDD), flash memory, semiconductor memory (e.g., various types of RAM or ROM), and so on.

[0030] Long-range communication (LRC) with remote devices outside the vehicle may be provided via one or more or all of a cellular chipset / component, a wireless modem, or a navigation and positioning chipset / component (e.g., GPS transceiver), all of which are listed collectively at 44. Short-range wireless connection may be established via an SRC device 46 (e.g., a Bluetooth® unit or an NFC transceiver), a DSRC component 48, and / or a dual antenna 50. The communication devices described above may enable data exchange as part of a periodic broadcast in a vehicle-to-vehicle (V2V) or vehicle-to-general communication (V2X) system, e.g., vehicle-to-infrastructure (V2I), and so on.

[0031] The CPU 36 receives sensor data from one or more sensing devices using, for example, photodetection, radar, laser, ultrasound, optics, infrared, or other suitable technologies, including short-range communication technologies (for example, DSRC) or ultra-wide-band (UWB) radio technologies, to perform, for example, automated vehicle operation or a vehicle navigation service. According to the illustrated example, the motor vehicle 10 may be equipped with one or more digital cameras 62, one or more range sensors 64, one or more vehicle speed sensors 66, one or more vehicle dynamics sensors 68, and the necessary filtering, classification, fusion, and analysis hardware and software for processing raw sensor data.The type, placement, number and interoperability of the distributed arrangement of vehicle sensors can be adapted individually or collectively to a specific vehicle platform to achieve the desired level of automation and the associated autonomous vehicle operation.

[0032] To drive the motor vehicle 10, an electrified drive train is capable of generating a traction torque and transmitting it to one or more of the drive wheels 26 of the vehicle. The drive train is Fig. 1 is generally represented by an electric traction motor (M) 78 connected to a rechargeable energy storage system (RESS), which may be in the form of a chassis-mounted traction battery pack 70. The traction battery pack 70 of Fig. 1 uses one or more battery modules 72, each containing a group of battery cells 74, such as stacked lithium, zinc, nickel, or organosilicon-class battery cells of the prismatic, pouch, or cylindrical type. One or more traction motors, such as the traction motor (M) 78, draw electrical power from and optionally supply electrical power to the battery pack 70. A power inverter module (PIM) 80 electrically connects the battery pack 70 to the motor(s) 78 and modulates the transfer of electrical current between them. The presented concepts are similarly applicable to HEV- and ICE-based powertrains. Module management, cell sensing, and module-to-module or module-to-host communication functions can be integrated directly into each battery module 72 and performed by an integrated electronics package, such as a wireless cell monitoring unit (CMU) 76.

[0033] Under abnormal operating conditions, the battery pack 70 may become damaged or malfunction, causing one or more of the cells 74 in the battery modules 72 to generate excessive heat, sometimes exceeding 400 to 500 degrees Celsius (°C). If left unchecked, the cell(s) may enter an uncontrollable self-heating cycle known as "thermal runaway," which can result in the release of high-temperature, high-pressure gases. The electrically interlocking covers for the gas vents of battery containers presented here facilitate early detection of battery operating characteristics that indicate an impending TR event. The battery monitoring systems presented here eliminate the need for individual pressure sensors that detect thermal runaway by monitoring an absolute or relative pressure at each cell.Instead, battery monitoring systems employ simplified, low-cost designs that combine a low-voltage interlock circuit with vent-covering pressure rupture discs for detecting thermal propagation. The pressure rupture disc is a type of pressure relief valve that opens to allow airflow through a liquid vent when a pressure differential develops between the two opposing major surfaces of the disc. An electrical interlock line is attached to or passes through the pressure rupture disc; if the rupture disc is forced open by high internal TR gas pressure, the line is designed to fail, allowing a system controller to detect the impending TR event.

[0034] The integration of a low-voltage interlock circuit with vent-covering burst caps on the battery system cells / modules enables quick and easy detection of a cell / module in thermal runaway, while reducing the number of system parts and costs, reducing manufacturing time and costs, and simplifying the overall system design. The pressure rupture disc is designed to physically open to relieve the pressure inside the corresponding battery container. When the pressure rupture disc is pushed open to relieve the internal gas pressure, it physically opens the electrical interlock circuit by deforming, breaking, or interrupting the wire. A system microcontroller or voltage sensor monitors the voltage on each leg of the interlock circuit during battery system operation.When one of the lines is physically opened due to the opening of the rupture disc, the microcontroller or voltage sensor detects a loss of voltage signal on that line. The microcontroller / sensor uses the voltage loss as a condition indicator that the pressure rupture disc has opened as a direct result of a thermal runaway event.

[0035] Fig. 2 shows a more detailed illustration of a representative battery assembly 100 that may be used as a lithium-class prismatic traction battery module for powering the electrified powertrain and electronic components of a motor vehicle, such as the vehicle hardware components 16 and the traction motor 78 of the motor vehicle 10 in Fig. 1. However, it should be appreciated that the described battery system concepts can be implemented in both vehicle and non-vehicle applications. Furthermore, references to a "battery assembly" in the specification and claims may refer to a battery pack assembly, a battery module assembly, a battery cell assembly, or any other applicable electrochemical device having a container that utilizes a liquid vent to remove gases generated within the cell and is susceptible to excessively high operating temperatures.

[0036] In the non-limiting example of Fig. 2, a group of prismatic battery cells 102 is stacked side by side and arranged in a rectangular array (e.g., five rows of thirty (30) cells per row) enclosed within an electrically insulated and protective battery container 104 (also referred to herein as a "module housing"). This module housing 104 may be divided into two distinct sections: a power electronics compartment 106 containing a selection of battery power electronics (e.g., traction PIM, CMU, sensor package, and so on); and a cell compartment 108 containing the stacked battery cells 102, a sensor lead assembly (not shown), and an interconnect board (not shown). The housing 104 may be constructed of a metallic, polymeric, or fiber-reinforced polymer (FRP) material, including combinations thereof, to meet various mechanical, manufacturing, and thermal design specifications.The battery module housing 104 may have a relatively flat construction with an octahedral shape, as shown, or may be constructed in other regular and irregular geometric configurations to accommodate application-specific parameters. Likewise, the battery assembly 100 may include rectilinear stacks of prismatic lithium-ion can cells sharing a common housing, as shown, or it may include a cluster or staggered arrangement of battery cells, may include pouch-like cells, cylinder-like cells, or another cell form factor, and / or may utilize other suitable battery technologies, such as those described above with respect to the battery cells 74 of FIG. Fig. 1 described.

[0037] An inspection view on the underside of Fig. Figure 2 is an enlarged, side sectional view showing a top wall 105 of the battery module housing 104 with a housing vent 107 through which gases generated by one of the cells 102 in the cell compartment 108 of the housing 104 are discharged. Similarly, each of the battery cells 102 of Fig. 2 with an electrically insulated and protective prismatic cell casing 112 (view from above) having a cell head 114 attached to an upper end of the cell casing 112. The cell head 114 is provided with a cell vent 111 ( Fig. 3A and Fig. 3B) through which gases generated by a jellyroll battery stack (shown obscured at 116) contained within the interior of the housing 112 are expelled. A jellyroll battery stack 116 may include one or more pairs of working electrodes (anode and cathode), a separating sheet disposed between and separating each pair of working electrodes, an insulating sheet wrapped around the stack, and an electrically neutral (liquid, solid, or quasi-solid) electrolyte for transferring ions between the anode(s) and cathode(s). Alternative system designs may use only a single gas evacuation vent (e.g., housing vent 107) or only gas evacuation cell vents (e.g., housing vents 111), which may take on similar or different shapes, sizes, and positions than those shown in the drawings.

[0038] To protect the internal contents of a battery assembly during normal system operation, a pressure rupture cover may cover and conceal the evacuation fluid opening in the battery container. As a non-limiting example, Fig. 2, a disc-shaped pressure rupture cap 120 is shown movably attached to the outer surface of the top wall 105 of the battery module housing 104 and covering the housing opening 107. Also shown is a rectangular pressure rupture cap 120, which is movably attached to an outer surface of the cell head 114 of the cell housing 112 and covers the cell vent 111. The vent cover plate 118 and the plate 120, both examples of a pressure rupture cover or cap, may each be manufactured as a one-piece structure formed entirely or partially from a high-temperature, flame-resistant, and slow-burning polymer material (e.g., polybenzimidazole (PBI), polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), and so on). The pressure burst covers illustrated may take on a variety of different shapes, sizes, and materials without deviating from the intended scope of this disclosure.

[0039] To allow the evacuation of gases generated in the cell from a battery container, a pressure rupture cap exposes the underlying fluid opening to allow a measurable fluid flow through the opening under certain operating conditions. As shown in Fig. For example, as best seen in Figure 3A, the pressure rupture cap 120 is fixedly mounted in a closed position in which the plate 118 covers and conceals the entire cell vent 111. In the closed position, the pressure rupture cap 120 is substantially flush with an outer surface of a sidewall of the cell head 114 and extends the length and height of the cell vent 111. It may also be desirable for the pressure rupture cap 120, when in the closed position, to fluid-tightly seal the vent opening 111 (e.g., with a polymer gasket or sealing ring). Once the internal pressure inside the cell housing 112 reaches or exceeds a predefined threshold for the burst pressure (for example, 40 bar), the pressure burst cap 120 is forced outwardly into an open position in which the plate 120 partially or completely exposes the cell vent 111, as best shown in Fig. 3B. It may also be desirable for the pressure rupture cap 120 to fully detach from the cell housing 112 and seal the vent opening 111 when moved to the open position. The pressure rupture cap 118 functions in a similar manner to the pressure rupture cap 120 to securely cover and selectively release the housing vent 107.

[0040] An electrical interlock circuit 122 monitors the battery assembly to detect the occurrence of any one of several predefined thermal events. In accordance with the illustrated example, the interlock circuit 122 is Fig. 2 by a network of electrified circuit lines 124 connected via interlock bus interfaces 126 to a stationary or remote processor, microcontroller, sensor device, or a network of controllers / processors / devices (collectively represented by the electronic battery control module (EBCM) 130 of Fig. 3A and Fig. 3B). For the individual battery cells 102, each circuit lead 124 may be fabricated as an electrical wire that is fixedly attached to and extends over the adjacent exterior surfaces of the pressure rupture cap 120 and the cell can head 114. For the battery module 100, the circuit lead 124 may be fabricated as an electrical wire that is routed through the interior of the module can 104 and extends into and through the pressure rupture cap 118 (for example, for insulation and weatherproofing). It should be noted that the circuit leads 124 may adopt any suitable electrical connector configuration and may be connected to the battery can and the pressure rupture cover in any suitable manner.

[0041] Each of the circuit leads 124 may consist essentially of a (jacketed or unsheathed) electrical wire made entirely or partially of an electrically conductive material (e.g., copper). In this case, the lead 124 may extend continuously from one end of the cell casing 112 across the plate 120 to the other end of the casing 112. To facilitate packaging and electrical connection of the battery cells 102, it may be most efficient to route the lead 124 along the top or bottom surface of the battery container and the pressure rupture cover. For each of the illustrated applications, the circuit lead 124 may be fixedly attached to the cap and battery (e.g., by adhesives, press fits, clamps, closures, etc.) or integrated into the cap and battery (e.g., by two-shot overmolding, threading, etc.).In each case, a left (first) side of the pressure rupture cap or panel 118, 120 is fixedly attached to a left (first) portion of the header 114 by a particular (first) segment of the circuit wire 124, while a right (second) side of the panel 120 is fixedly attached to a right (second) portion of the header 114 by another (second) segment of the wire 124. Optional system architectures may include a pin and barrel connector, a pin and socket connector, a single-pole connector, a crimp connector, a terminal block connector, and so on (in . Fig. 2 together with 128) which holds the pressure burst cap in the closed position and opens at a preset burst force.

[0042] During normal system operation, an interlock circuit line maintains its corresponding pressure rupture cap in a closed position; when subjected to a tensile / torsional force that meets or exceeds a preset breaking force, the line fails in whole or in part to generate an interlock circuit signal indicating a thermal event and simultaneously releasing the rupture cap. Fig. 3B, for example, the prismatic lithium battery cells 102 have entered the thermal runaway state, and the electrochemical jellyroll stack 116 within the cell casing 112 has begun to expel high-temperature and high-pressure gases. This gas creates an expansion force (arrow F TR ) on an inner side of the pressure burst cap 120, which pushes the plate 120 outwards (for example, vertically upwards in Fig. 3A). By pushing the plate 120 open, the expanding gas simultaneously exerts a tensile force on the locking circuit line 124. If the tensile force exceeds a preset threshold breaking force, the circuit line 124 deforms, cracks, or breaks, causing the pressure rupture cap 120 to move from the closed position ( Fig. 3A) into the open position ( Fig. 3B) and physically detaches from the cell casing head 114, as shown. The material, thickness, and / or cross-sectional geometry of the lead 124 can be designed so that the yield strength of the lead corresponds to a fracture force predicted upon insertion of the TR.

[0043] If the interlock circuit line 124 fails due to the release of TR gas, an open circuit signal is generated in the electrical interlock circuit 122 and detected by the EBCM 130. Specifically, the electrical interlock circuit 122 can maintain a continuous or constant electrical voltage across the entire circuit line 124 during normal operation of the battery system. The EBCM 130 systematically monitors the interlock circuit 122 for this voltage signal to ensure that none of the pressure rupture caps have opened. If a line 124 fails, an open circuit is created by the interruption of electrical voltage across the electrical interlock circuit; the EBCM 130 detects and characterizes this open circuit as a thermal runaway.When TR is detected, countermeasures can be taken to stop or mitigate the effects of the thermal event.

Claims

[1] Battery assembly (100) comprising: one or more electrochemical battery cells (102); a module housing (104) in which the one or more battery cells (102) are accommodated, wherein the module housing (104) has a wall with a fluid connection configured to that the gas generated by the one or more battery cells (102) is released through them; a pressure burst cap (118) movably mounted on the module housing (104) for selectively switching between a closed position in which the pressure burst cap (118) covers the fluid port, and an open position in which the pressure burst cap (118) at least partially releases the fluid connection; and an electrical interlock circuit (122) configured to be connectable to a controller (130) and comprising an electrical circuit line (124) attached to the pressure rupture cap (118) and the module housing (104), the electrical circuit line (124) maintaining the pressure rupture cap (118) in the closed position and configured to fail at a preset breaking force to generate an interrupt signal within the electrical interlock circuit (122) indicative of a thermal event; wherein the circuit line (124) is made as an electrical wire that is guided through the interior of the module housing (104) and extends into and through the pressure rupture cap (118). [2] The battery assembly (100) of claim 1, wherein the circuit lead (124) movably secures the pressure rupture cap (118) to the module housing (104) such that the pressure rupture cap (118) selectively moves from the closed position to the open position upon failure of the circuit lead (124). [3] The battery assembly (100) of claim 2, wherein the circuit lead (124) is comprised of an electrical wire formed from an electrically conductive material and fixedly attached to both the pressure rupture cap (118) and the module housing (104). [4] The battery assembly (100) of claim 1, wherein the circuit lead (124) ruptures at the preset breaking force such that the pressure burst cap (118) physically separates from the module housing (104). [5] The battery assembly (100) of claim 1, wherein a first side of the pressure rupture cap (118) is attached to a first portion of the module housing (104) by a first segment of the circuit line (124) and a second side of the pressure rupture cap (118) is attached to a second portion of the module housing (104) by a second segment of the circuit line (124). [6] The battery assembly (100) of claim 1, wherein the pressure rupture cap (118) extends over the fluid port and is flush with the wall in the closed position. [7] The battery assembly (100) of claim 1, wherein the electrical circuit line (124) maintains an electrical voltage across the electrical interlock circuit (122) that is detectable by the controller (130), and wherein the interrupt signal is generateable by interrupting the electrical voltage across the electrical interlock circuit (122) when the electrical circuit line (124) fails at the preset breaking force. [8] The battery assembly (100) of claim 1, wherein the circuit lead (124) comprises a pin and sleeve connector, a pin and socket connector, and / or a single-pole connector that maintains the pressure burst cap (118) in the closed position and is configured to fail by opening at the preset burst force. [9] The battery assembly (100) of claim 1, wherein the pressure rupture cap (118) is made of a polymeric material as a one-piece structure.

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