FIELD

The present disclosure relates generally to battery thermal runaway mitigation systems and methods, and in particular, to battery module-level temperature and effluent isolation systems and methods incorporating a ventilation system for isolating and venting effluents, which include liquid and/or gas, from cells within a module and from between individual modules.

BACKGROUND

The high energy density and efficiency of lithium ion batteries can in certain circumstances involve significant safety risks due to thermal runaway of one or more batteries. Thermal runaway in lithium ion batteries manifests a chain of events where battery cell temperature rapidly increases due to exothermic decomposition reactions within the battery cell, and such event may be further exacerbated by the flammability, combustion, and continued decomposition of the electrolytes within the battery cell. Thermal runaway events may occur spontaneously at 80°C, but have been reported to occur at temperatures as low as 66.5°C, and can lead to fire or explosion. While thermal runaway is generally uncontainable at the temperature of no return, because battery temperature tends to continually increase at a slow rate, and this serves as a safe warning system for approaching thermal runaway. See Wang, Q.; Ping, P.; Zhao, X.; Chu, G.; Sun, J.; Chen, C., Thermal Runaway Caused Fire and Explosion of Lithium Ion Battery. Journal of Power Sources 2012, 208, 210-224; Lyon, R. E.; Walters, R. N., Energy Release by Rechargeable Lithium-Ion Batteries in Thermal Runaway, 2016; and Wang, Q.; Sun, I.; Chu, G., Lithium Ion Battery Fire and Explosion. Fire Safety Science 2005, 8, 375-382, the entirety of the foregoing publications being incorporated herein by reference.

To improve the feasibility of lithium ion batteries in large machines and vehicles, preventative measures have been attempted to avoid thermal runaway events. The National Aeronautics and Space Administration (NASA) has conducted studies on lithium ion battery safety, naming three important thermal runaway event safety features, namely: a shutdown separator, a vent that is activated at a set pre-runaway temperature or pressure, and fusible links that melt and disconnect battery components. See Russell, S., Crewed Space Vehicle Battery Safety Requirements Revision D. 2017, the entirety of which is incorporated herein by reference. Separators, usually polyolefin microporous films, are perhaps the most widely used safety feature in lithium ion batteries and melt at approximately 130° C. NASA has utilized providing a physical distance between cells in a battery to avoid heat transfer, as well as providing heat-sink materials between cells. Additionally, NASA has employed steel tubes around battery cells to contain an explosion as much as possible.

Accordingly, it would be desirable to have systems and/or methods which stop or attenuate the effects of a battery thermal runaway event once the thermal runaway process has started.

SUMMARY

While venting is a technique employed in lithium ion batteries to mitigate negative outcomes of high internal temperatures, venting systems could potentially be improved to remove high temperature effluents of thermal runaway so as to contain failure of minor portions of a battery pack. Cell vents can be provided with weakened areas in a cell that rupture, or tear, below a specific pressure. Cell vents mitigate cell- level explosion by relieving pressure via releasing high temperature gas directly into the free air space between modules. This high temperature gas travels throughout the battery housing until reaching the single pack-level vent. The pack- level vent is a pressure-relief valve designed to open at a specific pressure and may or may not reseal. However, some cell- level vents may be employed with a liquid impermeable, gas permeable trap to collect liquid electrolyte spurting out during venting. Cell- level vents may release high temperature gas and smoke within the enclosed device, raising the temperature of adjacent modules before the gas or smoke can escape from the total enclosure through a surface- level vent. Thus, a characteristic of large- scale thermal runaway in battery packs can be that one module is the first to experience runaway, and then adjacent modules quickly follow because of the nearby accumulation of high-temperature vented effluents.

Generally, at least one implementation of the present disclosure includes a battery thermal runaway mitigation system and, in particular, a battery module-level temperature and effluent isolation system having a ventilation system for isolating and venting cell- level vented effluents from within a module and from between modules.

In an implementation of the present disclosure, isolated module venting systems mitigate accumulation of high-temperature vented effluents of one or more modules adjacent or proximate to the first-to-runaway module and/or other modules in the vicinity thereof. In implementations of the present disclosure, a module- level temperature and effluent isolation system is provided for adding a ventilation system to isolate and direct cell- level vented effluents within a module of a pack to at least one vent in the exterior of the pack, and also for removing effluent contact between separate modules with directional venting. Such venting could include dampers, flaps, doors, or the like which could be selectively and/or automatically actuated to allow venting or to discontinue venting responsive to an actuator connected thereto sensing one or more temperature, pressure, smoke and/or vapor levels falling outside of predetermined operational ranges. Physical barriers in the venting system can also serve to isolate high module temperatures. Modules could be subdivisions of cells in a defined space and/or in an open containment, and in such case can be supplied with a vent supplied with negative pressure so that cell- vented effluents are removed from the module area without entering the area of other modules within the pack. Modules could also be contained in a gastight vessel that does not allow for emission of effluents by physical barrier means and to the attached vent with or without applied negative pressure.

In implementations of the present disclosure, an energy storage device with risk of combustibility where combustion suppression is not applicable due to the self-reactivity of material internal to the device, is supplied with an insulating/isolating configuration of subdividing a collection of individual energy cells within the energy storage device that does not allow for gas to escape from any one subdivision to any other subdivision of the total device. A vent is provided on any face or surface of the subdivision allowing effluents to pass through, and a duct is attached to the vent on the subdivision leading to the exterior of the total device allowing vented effluents to exit the device completely. One or more heat shields or material may be provided for disallowing radiant heat in between adjacent surfaces, faces, corners, and/or edges of the box, case, container, etc., as well as surrounding ventilation components if ventilation components are adjacent to other subdivisions within the pack. It is to be understood, however, that if effluents cannot be totally contained or isolated, thermal runaway could still potentially be mitigated by reducing contact between modules in a significant manner, perhaps with a major portion of the effluents being vented with the minor portion of the effluent remaining in the pack and dispersed about adjacent modules.

In an exemplary implementation, 80% of the effluent could be vented, with the remaining 20% remaining in the pack.

In further implementations of the present disclosure, systems and methods include an apparatus for use in combination with an energy storage device having a container with a plurality of individual energy cells which experiences a risk of combustibility (where combustion suppression is not applicable due to the self-reactivity of material internal to the energy storage device). More specifically, the apparatus includes at least one portion or component configured for isolating and subdividing the plurality of individual energy cells into subdivisions and for preventing gas to escape from at least one subdivision to at least one other subdivision, and also, at least one vent in the at least one portion for selectively allowing effluents to pass therethrough. At least one duct is in fluid communication with the at least one vent leading to the exterior of the energy storage device, whereby, vented effluents are allowed to exit the energy storage device. Such implementations may include at least one heat shield or element substantially prohibiting radiant heat transfer between adjacent surfaces of the container, the plurality of individual energy cells, and the surrounding environment. It is to be understood that heat shields may be both separate from and/or a part of venting areas or materials, as desired, in various implementations of the present disclosure.

In other example implementations of the present disclosure, an apparatus is provided for use in combination with an energy storage device having a container with a plurality of individual energy cells capable of emitting effluent therefrom, and the apparatus includes at least one component configured for isolating and subdividing the plurality of individual energy cells into subdivisions and for preventing the effluent from escaping from one of the subdivisions to another subdivisions. At least one vent is in the component for selectively allowing the effluent from at least one of the energy cells to pass therethrough. At least one duct is in fluid communication with the at least one vent and the environment outside of the energy storage device, the at least one duct being configured for allowing the effluent to pass therethrough to the environment outside of the energy storage device, wherein, the vented effluent is allowed to exit the energy storage device. An actuator is configured to selectively or automatically allow or discontinue venting of the effluent in responsive to sensing at least one of temperature, pressure, smoke and vapor levels falling outside of a predetermined operational range.

In additional example implementations of the present disclosure, an energy storage system, which could include a lithium ion battery pack, is provided having a container with a plurality of individual energy cells capable of emitting effluent therefrom. The energy storage system includes at least one component configured for isolating and subdividing the plurality of individual energy cells into subdivisions and for preventing the effluent from escaping from one of the subdivisions to another subdivisions. At least one vent is in the component for selectively allowing the effluent from at least one of the energy cells to pass therethrough. At least one duct is in fluid communication with the at least one vent and the environment outside of the energy storage device, the at least one duct being configured for allowing the effluent to pass therethrough to the environment outside of the energy storage device, wherein, the vented effluent is allowed to exit the energy storage device. An actuator is configured to selectively or automatically allow or discontinue venting of the effluent in responsive to sensing at least one of temperature, pressure, smoke and vapor levels falling outside of a predetermined operational range.

In still further example implementations of the present disclosure, a method is provided including the steps of providing a container having a plurality of individual energy cells having fluid capable of becoming effluent and also providing at least one component configured for isolating and subdividing the plurality of individual energy cells into subdivisions and for preventing the effluent from escaping from at least one of the subdivisions to at least one other of the subdivisions. Also provided is at least one vent in the component for selectively allowing the effluent to pass therethrough. At least one duct is in fluid communication with the at least one vent and the environment outside of the energy storage device and is configured for allowing the effluent from an energy cell to pass therethrough to the environment outside of the energy storage device. An actuator is provided and is configured to selectively or automatically allow or discontinue effluent venting in responsive to sensing at least one of temperature, pressure, smoke and vapor levels falling outside of a predetermined operational range, and upon the actuator sensing at least one of temperature, pressure, smoke and vapor levels falling outside of a predetermined operational range, the method includes venting the effluent from the energy storage device.

The features, functions, and advantages that have been discussed can be achieved independently in various examples or may be combined in yet other examples, further details of which can be seen with reference to the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described exemplary aspects of the disclosure in general terms, various features and attendant advantages of the disclosed concepts will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, which are not necessarily drawn to scale, in which like reference characters designate the same or similar parts throughout the several views. The drawings form a part of the specification. Features shown in the drawings are meant as illustrative of some, but not all, embodiments of the present disclosure, unless otherwise explicitly indicated, and implications to the contrary are otherwise not to be made. Although in the drawings like reference numerals correspond to similar, though not necessarily identical, components and/or features, for the sake of brevity, reference numerals or features having a previously described function may not necessarily be described in connection with other drawings in which such components and/or features appear.

FIG. 1 is a schematic representation of an implementation of the present disclosure, including a battery module-level temperature and effluent isolation system having a ventilation system for isolating and venting cell- level vented effluents from within a module and from between modules;

FIG. 2 is another schematic representation of an implementation of the present disclosure, including a battery module-level temperature and effluent isolation system having a ventilation system for isolating and venting cell-level vented effluents, wherein at least one cell includes cell vents being weakened areas in the cell that tear when pressure exterior to the cell(s) applied to the weakened area(s) falls below a specific pressure; and

FIGs. 3A- 3F are a collection of schematic representations of various implementations of the present disclosure, including a battery module-level temperature and effluent isolation system having a ventilation system for isolating and venting cell- level vented effluents from within a module and from between modules.

DETAILED DESCRIPTION

Examples of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all examples of the disclosure are shown. Indeed, various exemplary aspects of the disclosure may be embodied in many different forms and should not be construed as limited to the examples set forth herein. Rather, these examples are provided so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like elements throughout.

Implementations, as described herein, of systems of module isolation, and methods emanating therefrom, may include a system, or apparatus, as shown in FIG. 1, generally 100 in the figures for use in combination with an energy storage device, generally 102, having a battery pack 104 with a plurality of individual modules, generally 106, with energy cells 108, which experience a risk of combustibility (where combustion suppression is not applicable due to the self-reactivity of material internal to the energy storage device).

More specifically, as shown in FIG. 1, the apparatus 100 includes at least one container or portion 104 having subdivisions, or compartments, 110a configured for isolating and subdividing the plurality of individual energy cells into subdivisions, or compartments,

110a and for preventing gas to escape from at least one compartment 110a to at least one other subdivision, and also, at least one vent 128 in the portion 130 for selectively allowing effluents from energy cells 108 to pass therethrough.

At least one duct 114 is in fluid communication with the at least one vent intake 142 leading to the exterior, or the environment outside of, the energy storage device, whereby, vented effluents are allowed to exit the energy storage device via an external pack lid or wall, generally W or 115. Such implementations may include container 104 having at least one heat shield or substance (not shown) substantially prohibiting radiant heat transfer between adjacent surfaces of the container 104, the plurality of individual energy cells 108, and the surrounding environment.

Such thermal isolation and venting as disclosed is applicable to any energy storage device that could be subdivided into modules by space or physical barriers. Venting configurations are provided for open (i.e., not gastight) modules 102a (FIG. 3C), with non- gastight lids 102 (FIGs. 3A and 3E) and/or closed (i.e., gastight) modules 102b (FIG. 3B).

Closed modules 102b function as cells grouped in a container that do not allow gas to escape the module except for the supplied vent 112 on the top 132 or any surface or face and/or wall of the container. Open modules 102a (FIG. 3C) could be a group of cells in a defined space within the pack, or a group of cells contained in an area by physical means, such as a box with a non-gastight lid or no lid.

Many battery packs are already supplied with a lid for covering modules made of metal or plastic. Ventilation in gastight modules may or may not be supplied with negative pressure to motivate module effluents, but venting in open modules often requires application of negative pressure, i.e., vacuum.

In an implementation of the disclosure having open modules 102a (FIG. 3C), the ventilation system will have an inlet 120 positioned adjacent to the grouping of cells, and upon a cell venting negative pressure, will pull vented effluents into an inlet, duct, vent, etc. such that vented effluents do not encroach upon adjacent modules. The open module ventilation system can be imagined as similar to an exhaust fan and can include an exhaust blower 124, fan, etc. If a non-airtight lid 126 is employed, a hole or opening 128 (FIGs. 1 , 3D and 3E) could be provided adjacent to or proximate to the vent opening to further encourage effluent movement toward the vent. A module could be open as a group of cells in a non barrier containment, as shown in FIG. 3E. To further prevent heat transfer between modules in a battery pack the walls, corners, or edges of modules adjacent to the walls, corners, or edges of other modules can be covered with fire blocking material 106a (FIG.l), such as intumescent putty, paint, etc.

In another implementation of the present disclosure, a battery, generally 130 (FIG. 2), which could be a lithium ion battery, is provided in a closed module case with a ventilation system assisted with negative pressure, where the module case is coated, painted, or lined with fire blocking material. Lithium ion battery packs often contain eight modules electrically and electronically connected within a large, common case. Modules are individually contained on four sides by four metal walls and a bottom, and a lid on the sixth, or top, side.

In at least one implementation of the present disclosure, the original lid is replaced with a lid 132 (FIGs. 1 and 3B) to contain the module in a way that if a cell-level vent were engaged, smoke and gas would stay within such modified, i.e., “new,” module-level containment 102b (FIG. 3A) prior to venting to the exterior of a battery pack in which the modules are contained. If desired, instead or, or in addition to lid 132, one or more walls or floor of the container 110 (or a wall of the battery pack 104) could be configured to vent effluent in a manner similar to the operation of lid 132 (FIG. 3C).

As shown in FIGs. 2 and 3F, an energy cell can have cell vents can be weakened areas 150 in a cell that tear when internal pressure in the cell(s) applied to the weakened area(s) reaches a specific pressure, thereby releasing effluent from the energy cell 108.

In another exemplary implementation of the present disclosure, the lid 132 (FIGs. 1 and 3B) of the module case is raised over the tops of the cells to allow a reasonable amount of space for effluent vent gases to reach the vent before exiting through the vent, and the lid 132 is secured to the four vertical containing side walls of the module- level containment, or container, 110 in a gastight fashion by way of any of various securing means (e.g. fasteners, adhesives, etc.). The vent 112 to the module case may be on a side or top of the newly contained module to direct cell venting effluent away from the cells within the module and out a surface-level vent in the walls or lid of the battery pack housing. A duct may be used between the new module-level containment 102b (FIG. 3B) and the battery pack exterior. In a further implementation as shown in FIG. 3F, a module 106 with a closed cell and a venting cell has a gastight sealed with an inlet 120 and an assisted vent 124.

As can be seen from the foregoing disclosure, implementations are provided wherein a module-level temperature and effluent isolation system includes a ventilation system using exhaust 124 to isolate and direct vented effluents from energy cells 108 within a module 106 of a battery pack 104 to at least one vent in the exterior of the pack 104, and also for removing effluent contact between separate modules 106 with directional venting. Such venting could include dampers, flaps, doors, or the like which could be selectively and/or automatically actuated to allow venting or to discontinue venting responsive to an actuator connected thereto sensing one or more temperature, pressure, smoke and/or vapor levels falling outside of predetermined operational ranges. Physical barriers in the venting system can also serve to isolate high module temperatures. Modules 106 could be subdivisions of cells in a defined space and/or in an open containment, and in such case can be supplied with a vent supplied with negative pressure so that cell- vented effluents are removed from the module area without entering the area of other modules within the pack. Modules could also be contained in a gastight vessel, such as containment 102b (FIG. 3B), that does not allow for emission of effluents by physical barrier means and to the attached vent with or without applied negative pressure.

Other implementations of the current subject matter will be apparent to those skilled in the art from a consideration of this specification or practice of the subject matter disclosed herein. Thus, the foregoing specification is considered merely exemplary of the current subject matter with the true scope thereof being defined by the following claims.