SYSTEMS FOR MULTIPLE USE OF ELECTROSTATIC DISCHARGE AND LIGHTNING PROTECTION FOR PREVENTION OF THERMAL RUNAWAY PROPAGATION CLMS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to, and the benefit of, Provisional Patent

Application No. 63/225,292, filed July 23, 2021, and titled “SYSTEMS AND METHODS FOR MULTIPLE USE OF ELECTROSTATIC DISCHARGE AND LIGHTENING PROTECTION SYSTEMS FOR PREVENTION OF THERMAL RUNAWAY PROPAGATION,” which is incorporated by reference herein in its entirety for all purposes.

FIELD OF INVENTION

[0002] The present disclosure generally relates to systems and methods for prevention of thermal propagation.

BACKGROUND OF THE INVENTION

[0003] The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may be inventions.

[0004] A battery module, for purposes of this disclosure, includes a plurality of electrically connected cells. These cells may, in turn, include a parallel, series, or combination of both, collection of electrochemical or electrostatic cells hereafter referred to collectively as “cells”, that can be charged electrically to provide a static potential for power or released electrical charge when needed. When cells are assembled into a battery module, the cells are often linked together through metal strips, straps, wires, bus bars, etc., that are welded, soldered, or otherwise fastened to each cell to link them together in the desired configuration.

[0005] A cell may be comprised of at least one positive electrode and at least one negative electrode. One common form of such a cell is the well-known secondary cells packaged in a cylindrical metal can, a pouch cell, or in a prismatic case. Examples of chemistry used in such secondary cells are Lithium Titanate Oxide (LTO), lithium cobalt oxide, lithium manganese, lithium iron phosphate, nickel cadmium, nickel zinc, and nickel metal hydride. Such cells are mass produced, driven for example by an ever-increasing consumer market that demands low-cost rechargeable energy for portable electronics, electric vehicles, and stationary energy storage.

[0006] Thermal runaway describes a process that may occur in a cell of a battery module that is accelerated by increased temperature, in turn releasing energy that further increases temperature. Thus, once a cell reaches some temperature level, the cell may go into thermal runaway. That temperature level is typically a “high” temperature and is often dependent on the chemistry of the cell.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] A more complete understanding of the present disclosure may be derived by referring to the detailed description and claims when considered in connection with the Figures, wherein like reference numbers refer to similar elements throughout the Figures, and where:

[0008] Figure 1 illustrates a dual use electrostatic protection system for transferring heat to the environment, in accordance with various embodiments; and

[0009] Figure 2 illustrates a dual use lightening protection system for transferring heat to the environment, in accordance with various embodiments.

SUMMARY

[0010] In an example embodiment, an aircraft thermal runaway protection system in an aircraft is disclosed, the system comprising: one or more of an electrostatic discharge system and a lightening protection system; and a battery module, wherein the battery module is connected to at least one of the electrostatic discharge system and the lightening protection system for thermal runaway protection of the battery module. [0011] In an example embodiment, an aircraft thermal runaway protection system in an aircraft is disclosed, the system comprising: a dual-purpose aircraft protection system comprising one or more of an electrostatic discharge system and a lightening protection system; and a battery module, wherein the battery module is connected to the dual-purpose aircraft protection system for thermal runaway protection of the battery module.

[0012] In an example embodiment, a method of protecting an aircraft from thermal runaway comprises: transferring energy, in the form of heat or electricity, from a battery module to a dual-purpose aircraft protection system comprising one or more of an electrostatic discharge system and a lightening protection system, wherein when the dual-purpose aircraft protection system is an electrostatic discharge system, the electrostatic discharge system is configured to both protect the aircraft from electrostatic discharge and to protect the aircraft from thermal runaway; and wherein when the dual-purpose aircraft protection system is a lightning protection system, the lightning protection system is configured to both protect the aircraft from electrostatic discharge and to protect the aircraft from thermal runaway.

DETAILED DESCRIPTION

[0013] The following description is of various example embodiments only, and is not intended to limit the scope, applicability or configuration of the present disclosure in any way. Rather, the following description is intended to provide a convenient illustration for implementing various embodiments including the best mode. As will become apparent, various changes may be made in the function and arrangement of the elements described in these embodiments, without departing from the scope of the appended claims. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Moreover, many of the manufacturing functions or steps may be outsourced to or performed by one or more third parties. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. As used herein, the terms “coupled,” “coupling,” or any other variation thereof, are intended to cover a physical connection, an electrical connection, a magnetic connection, an optical connection, a communicative connection, a functional connection, and/or any other connection.

[0014] For the sake of brevity, conventional techniques for mechanical system construction, management, operation, measurement, optimization, and/or control, as well as conventional techniques for mechanical power transfer, modulation, control, and/or use, may not be described in detail herein. Furthermore, the connecting lines shown in various figures contained herein are intended to represent example functional relationships and/or physical couplings between various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a modular structure.

[0015] Thermal runaway is a significant safety issue in the lithium-ion battery industry and a large variety of solutions have been proposed or implemented to attempt to address the safety issues. It is important that the thermal runaway not spread to neighboring cells, compounding the thermal event. Thus, it is very desirable that devices, systems and methods be devised that prevent thermal runaway in cells. Moreover, it is very desirable that devices, systems and methods be devised that prevent a cascade effect initiated from an initial thermal event.

[0016] Dual-purpose Electrostatic Discharge System

[0017] Electrostatic Dischargers (ESDs) exist on aircraft to safely dissipate potentially dangerous electrostatic charge that collects on the surface of aircraft. ESDs are also known as “static dischargers,” “static wicks,” or “static discharge wicks.” The devices take several forms, but generally are rod shaped devices that are distributed along the exterior of the aircraft wings, vertical stabilizers, winglets, and so forth. The ESDs are typically placed in locations proximate to where static charge tends to accumulate and dissipate from. For example, ESDs may be found on the trailing edges of aircraft ailerons, elevators, rudder, wing, horizontal and vertical stabilizer tips, and the like. The ESDs protect the aircraft by safely dissipating the charge. In an example embodiment, the ESDs are shaped with narrow tips that attract the charge and safely and slowly dissipate the charge into the air.

[0018] In an example embodiment, a battery heat dissipation system 100 is configured to dissipate heat through an electrostatic discharge system 130 on an aircraft. The battery heat dissipation system 100 comprises a device (e.g. battery module) 110, a heat transfer system 120, and an electrostatic discharge system 130.

[0019] In an example embodiment, the ESD system 130 comprises any suitable device for discharging electrostatic charge that may build up on the surface of an airplane. The ESD system 130 is at least partially exposed to airflow outside the aircraft. Thus, portions of ESD system 130 are configured to transfer heat to the passing airflow. In particular, surfaces of ESD system 130 that are exposed to passing airflow may be configured to cool the ESD system’s exterior surfaces for transferring heat from internal components of the aircraft. The ESD system 130 may comprise portions that are thermally conductive. Moreover, ESD system 130 is configured to perform both the purpose of electrostatic discharge and heat dispersion, from devices inside the aircraft, into the environment.

[0020] It is noted that although it is the static wicks that discharge the corona discharge into the atmosphere, the static wicks are typically connected, via a conductive path, to various parts of the aircraft, and typically are connected to the exterior surfaces of the aircraft, to the extent they may build up a corona voltage. Thus, the ESD system 130 may comprise not only the wicks, but the exterior surfaces of the aircraft and the connective path from those surfaces to the static wick. Any of these components, the exterior surfaces, the conductive path and the static wick, can be exposed to the passing air.

[0021] In an example embodiment, a device internal to the aircraft, such as a battery module, 110 may be coupled to ESD system 130. The device 110 may be coupled via a thermal path and/or electrical path. In one example embodiment, the device 110 is coupled to the ESD system via a thermal path (heat transfer system 120). In this example embodiment, the thermal path may comprise a solid material with relatively high thermal conductivity, such as aluminum, graphite, various metals, and the like. In this embodiment, the thermally conductive material may be in contact with both the device 110 and the ESD system 130 to transfer heat to the thermally conductive portions of the ESD system 130, from which the heat can be dissipated to the environment. In another example embodiment, the thermal path may comprise an active or passive thermally conductive fluid system, that is configured to transfer heat from the device 110 to the ESD system 130. Moreover, any suitable system for conducting heat from the device 110 to the ESD system 130 may be used.

[0022] In another example embodiment, the device 110 is coupled to the ESD system 130 via an electrical path. In this example embodiment, the device 110, e.g., a battery module, may discharge energy from the battery through the electrical path, to the ESD system 130. In this example embodiment, the ESD system 130 itself may serve as a resistor and may be configured to discharge the battery by the ESD system 130 heating up and then dissipating the heat to the environment. In another example embodiment, a resistance device may be located between the electrical path and the ESD system 130, but proximate the ESD system 130, such that as the resistance device heats up, the heat is transferred into the ESD system 130 and from there can be dissipated into the environment. In these ‘electrical path’ example embodiments, heat that may otherwise have been generated in a thermal runaway event of a cell or cells of the battery module, may be discharged or at least substantially discharged to the environment as opposed to being discharged to the internal portions of the aircraft. It is noted that the device may be any suitable device from which it is advantageous to transfer heat away from it to the outside environment. For example, the device 110 may comprise a lithium- ion battery, module, or pack, or any suitable energy storage device that is susceptible to thermal runaway.

[0023] Thus, the Electrostatic Discharge System described herein may be configured, in one example embodiment, to perform a dual-purpose: first to discharge electrostatic energy, and second to help remove heat and/or energy from an energy storage device to impede or eliminate thermal runaway.

[0024] Lightning Protection System

[0025] Lightning Protection Systems (LPS) exist in various aircraft to protect sensitive electronic devices and passengers from damage or injury when the aircraft is struck by lightning. In traditional aluminum clad aircraft, the metal performs this function by establishing a Faraday cage around the aircraft. Additionally or alternatively, the ‘skin’ around the cabin and interior compartments of the aircraft may be designed with a metal mesh that provides protection to the interior of the aircraft from lightening strikes. In an example embodiment, an aircraft surface may be made of a composite material, typically carbon fiber in a polymer matrix. Such surfaces do not conduct electricity well enough to create a Faraday cage. To resolve this, the composite matrix comprises layers that include expended metal mesh, perforated metal foil, or metal clad carbon fiber strands that establish a Faraday cage. The lightening protection system may further comprise expanded foils, embedded metallic wire, metallic picture frames, diverter strips, and/or the like.

[0026] In accordance with an example embodiment, an aircraft may comprise a heat dissipation system that works in conjunction with a lightening protection system on the aircraft. In an example embodiment, an aircraft may comprise a heat dissipation system comprising a device (e.g., a battery module) 210, the battery module may be connected electrically to lightening protection system 220. The device 210 may for example be electrically connected to the mesh or conductive wiring in the composite matrix of the surface structure.

[0027] Thus, the heat dissipation system 200 may be configured to conduct electricity from internal systems (e.g. device 210) to the surface. In an example embodiment, the device 110 is coupled to the LPS system 220 via an electrical path. In this example embodiment, the device 110, e.g., a battery module, may discharge energy from the battery through the electrical path, to the LPS system 220. In this example embodiment, the LPS system 220 itself may serve as a resistor and may be configured to discharge the battery by the LPS system 220 heating up and then dissipating the heat to the environment. In this example embodiment, heat that may otherwise have been generated in a thermal runaway event of a cell or cells of the battery module, may be discharged or at least substantially discharged to the environment as opposed to being discharged to the internal portions of the aircraft.

[0028] In an example embodiment, the battery module is thermally connected to the lightening protection system for transferring heat from the battery module to the lightening protection system, wherein the lightening protection system further transfers heat from the battery module to an environment surrounding the aircraft.

[0029] In an example embodiment, the lightening protection system performs its essential function of protecting the aircraft from lightning strikes but is also used as a heat dissipation mechanism due to its thermal conductivity and high surface area exposure to the outer surface of the aircraft. Thus, the LPS is configured as a dual-purpose LPS, serving to protect the aircraft from lightning strikes without, and battery thermal events within.

[0030] In another embodiment, an aircraft is configured to have both a dual- purpose LPS and a dual-purpose ESD. In this example embodiment, the LPS may be used in conjunction with the ESDs, simultaneously, to provide additional heat dissipation. In an example embodiment, both the ESD and the LPS are configured to be proximate the airflow over the exterior of the aircraft and thus to easily exchange heat/energy from the energy storage device 110/210 to the environment.

[0031] Thus, disclosed herein is a system, method and device for both reducing and delaying exothermic reaction due to external heating of a cell, all the way up to completely reducing and indefinitely delaying the exothermic reaction with sufficient discharge of the cell to an external dual-purpose system that is exposed to the air passing the airplane.

[0032] To mitigate or prevent thermal runaway, in accordance with an example embodiment, a battery module is configured to rapidly discharge a cell, to the environment through systems located on the exterior portions of the aircraft, when a predetermined temperature threshold is reached at the cell. A plurality of cells may be electrically coupled together to form a battery module.

[0033] In accordance with an example embodiment, the battery module is configured to keep the heat from the thermal event (including the discharging of the cells) away from the cells by discharging the energy to the environment through the ESD and LPS systems which serve as a load resistor for the discharged power. The load resistor, whether part of the ESD or LPS systems, or a stand alone resistor, may comprise resistive elements that may convert energy into heat.

[0034] In an example embodiment, surge protectors, wire bundle shields, ground straps, fuses and other means of isolating a lightning strike from internal electrical systems and people may be used.

[0035] In accordance with various example embodiments herein, the system

100/200 may further comprise a trigger system configured to initiate the transfer of heat from the battery module to at least one of the electrostatic discharge system and lightening protection system. By ‘transfer of heat’ the trigger system could initiate transfer of heat by any of the methods described herein (electrically discharging the battery reducing the energy available for thermal runaway heating, or directly removing heat from the cells. Some example embodiments may remove the heat without any trigger, such as where a thermal pathway is always present between the device and the ESD or LPS. However, in other embodiments, a trigger system may be configured to initiate the transfer based upon: a signal from a battery management system indicating that the battery module needs to be protected from thermal runaway; a temperature sensor indicating that a threshold temperature of the battery module has been exceeded; a thermal runaway sensor indicating that the battery module needs to be protected from thermal runaway; or a user command.

[0036] In an example embodiment, a method of protecting an aircraft from thermal runaway comprises: transferring energy, in the form of heat or electricity, from a battery module to a dual-purpose aircraft protection system comprising one or more of an electrostatic discharge system and a lightening protection system, wherein when the dual-purpose aircraft protection system is an electrostatic discharge system, the electrostatic discharge system is configured to both protect the aircraft from electrostatic discharge and to protect the aircraft from thermal runaway; and wherein when the dual-purpose aircraft protection system is a lightning protection system, the lightning protection system is configured to both protect the aircraft from electrostatic discharge and to protect the aircraft from thermal runaway.

[0037] While the principles of this disclosure have been shown in various embodiments, many modifications of structure, arrangements, proportions, elements, materials, and components (which are particularly adapted for a specific environment and operating requirements) may be used without departing from the principles and scope of this disclosure. These and other changes or modifications are intended to be included within the scope of the present disclosure and may be expressed in the following claims.

[0038] The present disclosure has been described with reference to various embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present disclosure. Accordingly, the specification is to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure. Likewise, benefits, other advantages, and solutions to problems have been described above with regard to various embodiments.

[0039] However, benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims. As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0040] When language similar to “at least one of A, B, or C” or “at least one of A, B, and C” is used in the claims or specification, the phrase is intended to mean any of the following: (1) at least one of A; (2) at least one of B; (3) at least one of C; (4) at least one of A and at least one of B; (5) at least one of B and at least one of C; (6) at least one of A and at least one of C; or (7) at least one of A, at least one of B, and at least one of C.