FIELD OF THE INVENTION

The present invention generally relates to battery powered electronic devices, and to controlled damaging of unmanned electronic devices powered by rechargeable lithium type batteries, in particular.

BACKGROUND OF THE INVENTION

A rechargeable lithium battery is a type of rechargeable battery commonly used in electronic products. Lithium batteries are characterized by very high energy density relative to other types of rechargeable batteries, for example more than double that of some nickel-metal hydride cells. A lithium-ion cell typically includes a metal oxide, sulfur, iron phosphate based, or air cathode; usually a graphite based (sometimes in combination with varying amounts of silicon) or carbon based, lithium titanate, anode; and an electrolyte from organic solvents. The anode and cathode undergo reversible reactions with lithium ions during charging and discharging. Rechargeable lithium batteries are also valued for high power density, quality performance over a broad range of temperatures, and low self-discharge rate. Moreover, rechargeable lithium batteries are adaptable for use in a variety of cell designs and configurations (e.g., prismatic, cylindrical, flat, coin or pouch designs), as well as with both liquid organic electrolytes, solid state electrolytes, and polymer electrolytes.

Rechargeable lithium batteries are also known for their susceptibility to combusting or exploding under certain conditions. This phenomenon is typically caused by electrical faults, particularly from internal short circuits, which can develop from an accumulation of latent defects and/or operational defects. Latent defects may involve the presence of contaminants, or manufacturing deficiencies, which could lead to physical contact between the anode and the cathode or their respective current collectors. Operational defects may include, for example: the growth of lithium dendrites caused by lithium metal plating in the battery; the growth of copper dendrites caused by copper plating (when the battery cells use copper current collectors); tears or holes formed in the separator due to physical or thermal stresses that create an opportunity for the anode and cathode to come into physical contact; and manufacturing faults during cell assembly. Short circuits in the lithium battery cell may also result from degradation and environmental effects, such as physical impacts (e.g., falls or vibrations), large swings in temperature, physical shocks, and the like. An internal (or external) short circuit can trigger an exothermic chain reaction of the chemicals in the cell. This may lead to a rapid temperature increase which can decompose the electrolyte to produce flammable gases and a consequent buildup of pressure in the cell, causing the cell to swell or rupture, along with possible decomposition of metal oxide cathodes. The combination of generated heat, decomposition of the metal oxide cathode, and flammable components of the electrolyte (in a decomposed or original form) may lead to combustion or ignition of the cell, and in some cases explosion. The combustion may subsequently propagate to other battery cells in a multi-cell module or pack, causing the entire battery to explode or go up in flames.

The rapid self-heating of a cell driven by exothermic reactions of cell materials releasing stored energy, where the reactions are accelerated by the increased temperature, which in turn instigates a further temperature increase in a positive feedback loop, describes a process known as “thermal runaway”. At a critical temperature, thermal runaway may cause a sudden increase in cell temperature leading to combustion. When a short circuit develops, internal lithium battery cell temperatures can rise in just a matter of seconds to unsafe levels, thereby inducing thermal runaway and consequent combustion, which can propagate to surrounding cells. As rechargeable lithium batteries are more reactive and have poorer thermal stability compared to other types of batteries, they are more susceptible to thermal runaway in certain conditions. Such conditions may include: high temperature operation (e.g., above 80 ^s C) or overcharging (e.g., high rate charge at low temperatures); conditions that may produce internal shorts, such as lithium plating or copper plating; and/or manufacturing defects or defects resulting from use, misuse, or abuse. At elevated temperatures, cathode decomposition produces oxygen which reacts exothermically with organic material in the battery cell (e.g., flammable organic solvent electrolyte and carbon anode). The highly exothermic chain reaction is extremely rapid and can induce thermal runaway and reach excessive temperatures and pressures (e.g., 700 ^s C to 1000 ^s C and about 500psi) in only a few seconds. Once the chain reaction begins it cannot effectively be stopped nor extinguished and will ultimately lead to combustion of the cell and (following the cell propagation effect) of the entire battery.

In summary, an initial internally developed fault or defect in a rechargeable lithium battery cell can trigger an internal short circuit, which in turn elicits heating and subsequently exothermic chain reactions, leading to irreversible thermal runaway and ultimately combustion/explosion. Cell heating from high environmental temperatures, rapid charging, high load discharging, and proximity between neighboring cells in a battery package, are factors that increase the potential for thermal runaway.

Serious safety hazards are thus posed by a wide range of rechargeable lithium battery powered devices, ranging from laptops and cellphones to electric or hybrid vehicles, with dangerous incidents frequently reported and numerous product recalls. The risk of such incidents is rising as the demands on the performance and size of cell and battery package increases, the cell energy density becomes greater, and rechargeable lithium batteries grow more prevalent in commercial products. Combustion of lithium battery cells may occur even under normal use without any prior warning. Consequently, many manufacturers attempt to minimize or prevent the possibility of lithium battery combustion by various means, such as by employing diagnostic tools and by ensuring suitable storage and operating conditions of the device. Some devices incorporate protection mechanisms for rechargeable lithium batteries at the cell or battery package level to protect against over-charging, over-discharging, overheating, short-circuiting or other potentially dangerous conditions. For example, some mechanisms may terminate the battery current if certain operating limits are exceeded. However, in certain cases it may be desirable to actively destroy or damage an electronic device powered by a lithium battery. Such a destruction needs to be carried out in a safe, controlled, and secure manner while avoiding harm to individuals and surrounding property. For example, an electronic device may contain sensitive or secretive information and/or confidential material or components which needs to be kept away from unauthorized parties. The device may be situated remotely or in a location with limited or difficult access, which can complicate the ability to remove confidential information or material from the device and/or render it unusable, undecipherable and/or inaccessible.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there is thus provided a method for initiating a combustion of a rechargeable lithium battery powering an unmanned electronic device. The method comprises the step of altering a state of a selected initiation cell of the rechargeable lithium battery, responsively to a trigger event, the altered state causing an internal short circuit in the initiation cell, triggering a thermal runaway process and combustion of the battery, for damaging at least a targeted portion of the device. Altering a state of a selected initiation cell of the battery may comprise modifying at least one electrical property or thermal property of the initiation cell, via a cell state regulator coupled to the battery, using energy derived from the battery. Altering a state of a selected initiation cell of the battery may comprise at least one action of: externally heating the initiation cell; overcharging the initiation cell; applying a reverse polarity to the initiation cell; applying an external short circuit to the initiation cell; or applying a forced discharge to the initiation cell. Externally heating the initiation cell may comprise applying heat to the initiation cell via a heating element coupled to at least a portion of the initiation cell, the heating element powered by electrical energy extracted from at least one cell of the battery. The method may further comprise a preliminary procedure of selecting a modality for causing an internal short circuit in the initiation cell to trigger thermal runaway, in accordance with at least one parameter or condition. The method may further comprise a preliminary procedure of selecting the initiation cell in accordance with at least one parameter or condition. The initiation cell may be selected based on at least one parameter of: a maximum power output available from at least one cell of the battery; a minimum energy required to initiate thermal runaway in at least one cell of the battery; and a maximum damage distance respective of dimensions of the battery. The trigger event may comprise receiving an activation signal from a remote activator. The trigger event may comprise a detection of at least one initiation condition in accordance with preloaded instructions in the device. The device may comprise an unmanned vehicle.

In accordance with another aspect of the present invention, there is thus provided a system for initiating a combustion of a rechargeable lithium battery powering an unmanned electronic device. The system comprises a cell state regulator, coupled to the rechargeable lithium battery and configured to alter a state of a selected initiation cell of the rechargeable lithium battery, responsively to a trigger event, the altered state causing an internal short circuit in the initiation cell, triggering a thermal runaway process and combustion of the battery, for damaging at least a targeted portion of the device. The cell state regulator may be configured to alter a state of a selected initiation cell by modifying at least one electrical property or thermal property thereof, using energy derived from the battery. Altering a state of a selected initiation cell of the battery may include at least one action of: externally heating the initiation cell; overcharging the initiation cell; applying a reverse polarity to the initiation cell; applying an external short circuit to the initiation cell; or applying a forced discharge to the initiation cell. The cell state regulator may comprise a heating element coupled to at least a portion of the initiation cell, the heating element configured to externally heat the initiation cell, the heating element powered by electrical energy extracted from at least one cell of the battery. The system may further comprise at least one sensor, configured for detecting at least one parameter of the battery, wherein the state of the initiation cell is altered in accordance with the detected parameter. The system may further comprise a processor, configured for selecting a modality for causing an internal short circuit in the initiation cell to trigger thermal runaway, in accordance with at least one parameter or condition. The system may further comprise a processor, configured for selecting the initiation cell in accordance with at least one parameter or condition. The initiation cell may be selected based on at least one parameter of: a maximum power output available from at least one cell of the battery; a minimum energy required to initiate thermal runaway in at least one cell of the battery; and a maximum damage distance respective of dimensions of the battery. The system may further comprise a remote activator, communicatively coupled with the device, and configured to send an activation signal to the device, where the trigger event comprises receiving an activation signal from the remote activator. The trigger event may comprise a detection of at least one initiation condition in accordance with preloaded instructions in the device. The device may comprise an unmanned vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which:

Figure 1 is a schematic illustration of a system for initiating a combustion of a rechargeable lithium battery powering an unmanned electronic device, constructed and operative in accordance with an embodiment of the present invention;

Figure 2 is an illustration of an exemplary arrangement for a system for initiating a combustion of a rechargeable lithium battery using an external heating approach, constructed and operative in accordance with an embodiment of the present invention;

Figure 3A is an illustration of a first exemplary configuration of an initiation cell in a rechargeable lithium battery pack, constructed and operative in accordance with an embodiment of the present invention;

Figure 3B is an illustration of a second exemplary configuration of an initiation cell in a rechargeable lithium battery pack, constructed and operative in accordance with an embodiment of the present invention;

Figure 4 is a schematic illustration of the propagation of thermal runaway within a battery pack leading to an explosion, operative in accordance with an embodiment of the present invention; and

Figure 5 is a flow diagram of a method for initiating a combustion of a rechargeable lithium battery powering an unmanned electronic device, operative in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention overcomes the disadvantages of the prior art by providing a novel method and system for actively implementing a controlled damaging of an unmanned electronic device powered by a rechargeable lithium battery, by initiating a combustion of the lithium battery. The disclosed method and system is operative to instigate an irreversible thermal runaway process in the device battery by altering a state of at least one cell of the battery, such as by modifying at least one electrical property or thermal property of the cell, to cause an initiated (i.e., not spontaneous) combustion of the battery and subsequent damaging or destruction of the electronic device powered by the batter. For example, an external heating element in proximity to one of the cells in a multi-cell lithium battery may be directed to heat the proximal cell using electrical energy derived from other cells in the battery pack. The operating voltage of the heating element may be scaled to the voltage of the group of cells from which the electrical energy is derived. A trigger event to activate the initiation cell combustion may include the receipt of a trigger signal from a remote source, or the detection of selected trigger conditions by the device itself.

The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. For a better understanding of certain embodiments and to show how the same may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings in which like numerals designate corresponding elements or sections throughout.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

As used herein, the singular forms “a”, “an” and “the” are intended to include plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” or “comprising”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements components and/or groups or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups or combinations thereof. As used herein the terms “comprises”, “comprising”, “includes”, “including”, “having” and their conjugates mean “including but not limited to”. The term “consisting of’ means “including and limited to”.

As used herein, the term “and/or” includes any and all possible combinations or one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative (“or”).

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and claims and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. Rather, these terms are only used to distinguish one element, component, region, layer and/or section, from another element, component, region, layer and/or section.

It will be understood that when an element is referred to as being “on”, “attached” to, “operatively coupled” to, “operatively linked” to, “operatively engaged” with, “connected” to, “coupled” with, “contacting”, “added to”, etc., another element, it can be directly on, attached to, connected to, operatively coupled to, operatively engaged with, coupled with, added to, and/or contacting the other element or intervening elements can also be present. In contrast, when an element is referred to as being “directly contacting” another element or “directly added” to another element, there are no intervening elements and/or steps present.

Whenever the term “about” is used, it is meant to refer to a measurable value such as an amount, a temporal duration, and the like, and is meant to encompass variations from the specified value, as such variations are appropriate to perform the disclosed methods. Certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Whenever terms “plurality” and “a plurality” are used it is meant to include, for example, “multiple” or “two or more”. The terms “plurality” or “a plurality” may be used throughout the specification to describe two or more components, devices, elements, units, parameters, or the like. The term set when used herein may include one or more items. Unless explicitly stated, the method embodiments described herein are not constrained to a particular order or sequence. Additionally, some of the described method embodiments or elements thereof can occur or be performed simultaneously, at the same point in time, or concurrently.

As used herein the term “method” refers to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures.

Throughout, this disclosure mentions “disclosed embodiments”, “disclosed systems” and “disclosed methods”, which refer to examples of inventive ideas, concepts, and/or manifestations described herein. Many related and unrelated embodiments are described throughout this disclosure. The fact that some “disclosed embodiments” are described as exhibiting a feature or characteristic does not mean that other disclosed embodiments necessarily share that feature or characteristic.

This disclosure employs open-ended permissive language, indicating for example, that some embodiments “may” employ, involve, or include specific features. The use of the term “may” and other open-ended terminology is intended to indicate that although not every embodiment may employ the specific disclosed feature, at least one embodiment employs the specific disclosed feature. The terms “user” and “operator” are used interchangeably herein to refer to any individual person or group of persons using or operating a method or system according to an embodiment of the present invention, such as a person implementing a controlled combustion of an unmanned electronic device.

The term “battery” in general, and the terms “lithium battery” or “rechargeable lithium battery (RLB)” in particular, as used herein refers to any lithium based rechargeable battery containing any number of electrochemical cells (or groups of cells) connected in any configuration (e.g., series, parallel, and combinations of series and parallel), including also a single-celled battery, as well as encompassing all types of cell form factors (e.g., including but not limited to: cylindrical, prismatic, pouch, coin, and button cells), sizes, and cell designs (e.g., including but not limited to: jelly-roll design cells, bobbin cells, cells with Z-fold electrodes, cells with dog-bone folded electrodes, cells with elliptically folded electrodes, and parallel plate stacked electrode cells, whether bi-polar or not). A LIB generally includes at least a pair of electrodes (anode, cathode), an electrolyte for conducting lithium ions (liquid, solid, semi-solid and/or polymer), and a separator. The battery may be integrated with or form part of at least one electrical or electronic device or component (e.g., including but not limited to at least one of: a capacitor; a supercapacitor; a printed circuit board (PCB); a semi-conductor device, electronics, a passive electronic component, a battery management system; an electronic control unit; a power adapter; a charger; a wireless charging system; a fuse; a sensor; a positive temperature coefficient (PTC) device; a current interrupt device (CID); and any combination thereof). The terms “battery” and “battery pack” are used interchangeably herein. It is noted that “lithium battery” herein encompasses Li-metal rechargeable batteries, lithium-ion (Li-ion) rechargeable batteries, and Li-ion polymer rechargeable batteries, as well as these types of batteries as including but not limited to: reserve type batteries, thermal type batteries, so-called lithium-ion capacitors, and Li-air and Li-sulfur batteries. The disclosed embodiments are applicable to all types of rechargeable lithium battery chemistries, including but not limited to cathodes whose active material is based on nickel manganese cobalt oxides (NMC), nickel cobalt aluminum oxides (NCA), lithium cobalt oxides (LCO), lithium ion manganese oxide (LMO), sulfur, and lithium iron phosphates (LFP) (each cathode in a range of effective stoichiometries), anodes whose active material is based on graphite, hard carbon, soft carbon, lithium titanate (LTO), lithium metal, silicon, silicon-carbon composites, silicon graphite composites, tin.

The term “combustion” is used herein broadly to encompass all forms of destructive battery states following or caused by thermal runaway, including but not limited to a lithium battery and/or at least one cell thereof, undergoing, at least partially: combustion, ignition, a fire, explosion, enflaming, rupturing, leaking of electrolyte solution, swelling, venting, and the like.

The term “damage” is used herein to broadly encompass any form of harm, damage, or destruction of an electronic device, rendering at least a portion of the device (including but not limited to electronics, components or data contained in the device) unusable, undecipherable, unidentifiable, and/or inaccessible.

Reference is now made to Figure 1 , which is a schematic illustration of a system, generally referenced 100, for initiating a combustion of a rechargeable lithium battery powering an unmanned electronic device, constructed and operative in accordance with an embodiment of the present invention. System 100 is configured to implement a controlled damaging of an electronic device 120, which is powered by a lithium-ion battery 122 composed of a plurality of battery cells 124. Device 120 is described herein for exemplary purposes as an unmanned aerial vehicle (UAV) or “drone” but may alternatively represent a different type of unmanned electrical vehicle operating in any environment (e.g., air, land or sea). More generally, the disclosed embodiments may be applied to any device that is powered by at least one multi-cell rechargeable lithium battery. Non-limiting examples may include: electric or hybrid vehicles, such as automobiles, buses, vans, aircrafts or maritime vessels; two-wheeled or three-wheeled electric/hybrid vehicles; electric bicycles (e-bikes); electric scooters (e-scooters); appliances; electronic devices; medical devices; mobile devices; energy storage devices; uninterrupted power supplies; batteries for device charging; batteries for electric vehicle charging; satellites; robots; and the like.

System 100 includes an activator 115 of an operator unit 1 10, and a cell state regulator 126 of electronic device 120. Operator unit 1 10 may be remotely located from electronic device 120. Activator 1 15 is communicatively coupled with cell state regulator 126, such as to enable transmission (and optionally reception) of signals, over any suitable data communication channel or network, using any type of channel or network model and any signal transmission protocol (e.g., wired, wireless, radio, WiFi, Bluetooth, and the like).

Operator unit 1 10 may be embodied by any type of electronic device with computing and signal transmission/reception capabilities, including but not limited to: a mobile computer; a desktop computer; a smartphone; a laptop computer; a netbook computer; a tablet computer; or any combination of the above. Alternatively, operator unit 1 10 may be a basic remote-control device, such as embodied only by activator 1 15. It is noted that system 100 may generally include a plurality of operator units operable by multiple respective users, although a single operator unit 110 is depicted for exemplary purposes.

Activator 115 is configured to send an activation signal 1 17 to cell state regulator 126 to trigger the activation of an initiated battery combustion. Activation signal 117 may be, for example, a radio frequency signal in any wavelength, or a wired or wireless communication signal. Cell state regulator 126 is configured to alter a state of at least one battery cell 124 of battery 122, as will be elaborated upon further hereinbelow.

The components and devices of system 1 10 may be based in hardware, software, or combinations thereof. It is appreciated that the functionality associated with each of the devices or components of system 1 10 may be distributed among multiple devices or components, which may reside at a single location or at multiple locations. System 100 may optionally include and/or be associated with additional components not shown in Figure 1 , for enabling the implementation of the disclosed subject matter. For example, operating unit 1 10 may include: an electrical sensor (not shown), for detecting one or more electrical properties of the battery, such as a voltage or current measuring device; a processor (not shown), for receiving and processing information from other components, such as detected parameters of the battery; a user interface (not shown) for allowing a user to control various parameters or settings associated with system 100; a memory or storage device (not shown), for storing information relating to the operation of system 100; a display device (not shown) for visually displaying information relating to the operation of system 100, and/or a camera or imaging device (not shown) for capturing images of the operation of system 100.

The operation of system 100 will now be described in general terms, followed by specific examples. An authorized decision is made to implement a controlled damaging of unmanned electronic device 120. In particular, an owner or operator of device 120, or other individual authorized to decide on the damaging thereof, resolves to implement a controlled damaging, such as in order to prevent unwanted access to confidential material contained in device 120. After the decision is made, the operator activates an initiated combustion of battery 124 by deploying activator 1 15, such as via a manual action (e.g., by pressing a button or toggling a switch) or by entering a command (e.g., via a touch-screen user interface, or by providing speech instructions in a voice recognition setup). Activator 1 15 may also be configured to receive instructions remotely, such as from: a service center, a monitoring station, and/or a remote server, application or database in a cloud computing network, where the instructions may be provided in real-time or at a predetermined, programmable, or self-initiated time (e.g., based on a set of rules).

Upon deployment, activator 115 sends an activation signal 117 to device 120. Cell state regulator 126 receives activation signal 117 and initiates a combustion of battery 122. The initiation may be performed immediately or upon the fulfillment of at least one initiation condition, such as a scheduled time in the future, conditions in the environment in which the device is operating (e.g., weather or climate conditions), detection of the device by unauthorized parties, and/or based on at least one parameter of battery 122 (e.g., state of charge, temperature, voltage). According to an embodiment of the present invention, device 120 is preloaded with activation trigger instructions (i.e., and does not need to receive an activation signal from operator unit 1 10), such that device 120 is programmed or configured to automatically initiate a battery combustion process if and when selected initiation conditions are met, such as based on a scheduled time, based on environmental conditions (such as weather), based on an unauthorized detection or accessing of device 120, and/or based on at least one detected parameters of battery 122. To initiate a combustion of battery 122, cell state regulator 126 alters a state of a selected cell 124 of battery 122 to cause an internal short circuit and trigger a thermal runaway process. In particular, cell state regulator 126 modifies at least one electrical property or thermal property of an initiation cell 124i of battery cells 124. Initiation cell 124i may be a single cell or a group of cells in any position of the battery cell pack. The initiation cell 124i may be selected based on various criteria. For example, selection criteria may include: the position or location of the initiation cell 124i within the battery pack 122; the proximity of the initiation cell 124i to at least one target item in device 120 to be damaged; and the type and size of the cell relative to the size of the target item.

Cell state regulator 126 may modify at least one property of initiation cell 124i to alter a state thereof. The altered state is operable to introduce one or more defects into initiation cell 124i causing an internal short circuit and triggering thermal runway leading to combustion of initiation cell 124i. The combustion of initiation cell 124i propagates to other battery cells 124 which undergo combustion in turn, resulting in combustion of battery 122 and the damaging of (at least a targeted portion of) device 120. Such propagating combustion may serve to maximize the effectiveness of the damage incurred by device 120.

In one example, cell state regulator 126 applies external heating to initiation cell 124i to trigger thermal runaway. The external heating may be delivered via a heating element in proximity to initiation cell 124i. For example, the heating element may be coupled to a top portion, a bottom portion, and/or a side portion of initiation cell 124i. The heating element may receive electrical energy extracted from other cells 124 of battery 122 and direct the extracted energy in the form of heat to initiation cell 124i. External heating of an initiation cell may result in a high likelihood of an internal short circuit and thermal runaway regardless of the state of the cell, however the time required to initiate combustion may be dependent on several factors, such as the state of charge of the initiation cell, the power rating of the heating element, and the electrical power supplied to the heating element. The input voltage of the heating element is scaled to the voltage that can by supplied by the battery cells from which the electrical energy is derived. The heating element may be configured in an optimal location with respect to the initiation cell in order to maximize the effect of the heating to initiate combustion. The geometry of the heating element may be adapted to maximize heat flow to the initiation cell. An increased power rating of the heating element generally reduces the time to initiate combustion. In general, the higher the state of charge of the initiation cell, the greater the force of the combustion.

Reference is made to Figure 2, which is an illustration of an exemplary arrangement for a system for initiating a combustion of a rechargeable lithium battery using an external heating approach, constructed and operative in accordance with an embodiment of the present invention. The arrangement includes a battery 132 composed of multiple battery cells 134, with a heating element 136 coupled to an initiation cell 134i. In certain cases, a lithium battery is separated from electronic device components by a separator, such as for safety reasons. In the example of Fig.2, battery 132 is separated from a target electronic device 130 (depicted as a printed circuit board (PCB) for exemplary purposes) by a distance of “x” via a separator 137 of thickness “y”. The destructive force of the initiated combustion event is operable to overcome distance “x” and thickness “y” of separator 137. Battery 132 may be embodied for example by lithium-ion battery pack having a 6S2P configuration with 18650 cells. The initiation cell may be in any position. For example, Figure 3A illustrates a first exemplary configuration of an initiation cell (144i) in a rechargeable lithium battery pack 142 having a 6S2P configuration, where the initiation cell 144i is positioned at a corner location of battery pack 142. For another example, Figure 3B illustrates a second exemplary configuration of an initiation cell (154i) in a rechargeable lithium battery pack 152 having a 6S2P configuration, where the initiation cell 154i is positioned at a middle edge location of battery pack 152. The location of the initiation cell (which may be a group of cells) may depend on the form factor of the cells in a pack of cells, the location of the device target portion to be damaged, the design of the device, and other factors. The location of the initiation cell and its orientation with respect to the propagation cells may be selected so as to maximize the effect of the initiated combustion.

Upon activation, heating element 136 applies heat to initiation cell 134i. The applied heat causes an internal short circuit in initiation cell 134i triggering thermal runaway and combustion, followed by a propagating combustion along other cells 134 in battery 132. The initiated combustion may be configured with sufficient force to ensure that the propagating combustion reaches all other cells 134 of battery 132, or at least a plurality of cells 134 thereof. The operation of heating element 136 may be effected from electrical power extracted from cells 134 of battery 132, which may include power derived from initiation cell 134i itself. Accordingly, there is no need for an external power source to operate heating element, as all required power may be derived internally from battery 132.

In another example, altering a state of the initiation cell is achieved by overcharging. Referring back to Figure 1 , cell state regulator 126 may overcharge initiation cell 124i to trigger thermal runaway, such as by delivering a constant current to initiation cell 124i. This may require preliminary charging of battery to a selected initial state of charge (SOC) prior to overcharging. The excess electrical energy in the cell from overcharging leads to generated heat and thermal runaway. An overcharging approach may result in a high likelihood of an internal short circuit and thermal runaway. However, combustion may take a relatively long time if the initiation cell is at a low state of charge. Overcharging may drain energy from other cells that is not used to initiate thermal runaway, and could lead to venting, swelling, or rupturing of the cell instead of combustion.

A further example of altering a cell state relates to the cell polarity. In particular, cell state regulator 126 may apply a reverse polarity to initiation cell 124i to trigger thermal runaway, such as by first fully discharging cell 124i, for example via an external resistor, and then recharging cell 124i with the polarities reversed. This approach does not require preliminary charging of battery 122 but may take a relatively long time to initiate combustion. Applying a reverse polarity may drain energy from other cells that is not used to initiate thermal runaway.

In yet another example, cell state regulator 126 may apply an external short circuit to initiation cell 124i to trigger thermal runaway, such as by connecting the positive and negative cell terminals to an external resistor. An external short-circuiting approach may not always generate enough heat, especially at low states of charge, to lead to thermal runaway or cell combustion.

In yet a further example, cell state regulator 126 may apply a forced discharge of initiation cell 124i to a low or negative voltage (e.g., OV) so as to trigger thermal runaway. A forced discharging approach may take a relatively long time to initiate combustion and may drain energy from other cells that is not used to initiate thermal runaway.

The initiation cell may need to undergo a preliminary preparation prior to the cell state alteration. For example, it may be necessary to remove at least one protective component from the battery cell, such as a positive temperature coefficient (PTC) or a current interrupt device (CID). If the PTC is not removed, then the cell state alteration may be terminated before reaching combustion since the cell temperature will trigger the PTC to prevent current inflow into the cell. If the CID is not removed, then the cell state alteration may be terminated before reaching combustion since high cell currents applied in the cell state alteration will trigger the CID to prevent current inflow into the cell. It may also be necessary to apply preliminary charging of the initiation cell to a selected state of charge (SOC) sufficient to initiate a significant combustion. The preliminary charging may be optimized such that the cell is brought to a sufficient level of SOC as quickly as possible to maximize the energy available for combustion. The cell can then be subjected to external heating, overcharging or other property modification directed to trigger thermal runaway and initiate combustion.

The series-parallel connections between the cells in the pack may be reconfigured near the time of the activation trigger of the initiation cell so as to optimize the pack current and voltage for a given thermal runaway generation approach. A MOSFET switching circuit may be employed to isolate the initiation cell from the rest of the cells in the battery and/or to reconfigure the series-parallel connections to maximize the electrical energy supplied to the initiation cell.

The cell state alteration may take into account relevant information, such as an initial state or characteristics of battery 122, which may be obtained using one or more battery monitoring devices. For example, a processor (not shown) may determine a maximum power output available from a selected cell, and/or may determine a minimum energy required to initiate thermal runaway in a selected cell, for evaluating the selected cell suitability as an initiation cell. The processor may evaluate several possible approaches for initiating thermal runaway in the selected cell, according to the received data, and may determine and select an optimal approach, such as in order to optimize the combustion and/or to maximize the likelihood and impact of damage to the target device portion.

The state alteration of initiation cell 124i is directed to cause internal defects and an internal short circuit that leads to thermal runway and the resultant combustion of initiation cell 124i. The combustion of initiation cell 124i triggers a propagating combustion of adjoining cells 124 of battery 122, which in turn propagates to further cells 124 until eventually all (or at least a plurality) of cells 124 in battery 122 undergoes combustion. Reference is made to Figure 4, which is a schematic illustration of the propagation of thermal runaway within a battery pack leading to an explosion, operative in accordance with an embodiment of the present invention. In a first stage 161 , a battery pack is provided. In a second stage 162, an initiation cell (located at the lower lefthand corner) undergoes an cell state alteration to cause an internal short circuit and trigger thermal runaway. In a third stage 163, the combustion of the initiation cell propagates to an initial first group of cells adjacent to the initiation cell. In a next stage 164, the combustion propagates to a larger group of cells adjacent to the first group. In a next stage 165, the combustion has propagated to substantially all of the battery cells. In a final stage 166, the battery has exploded.

It will be appreciated that the disclosed embodiments may provide for a reliable and safe technique for actively damaging an unmanned electronic device powered by a rechargeable lithium battery. The disclosed embodiments may provide enhanced security, such as by preventing the transfer of assets or confidential material to unwanted parties, and may extend mission capabilities in the case of a drone device. The disclosed embodiments may be implemented in a straightforward manner, using an existing onboard battery to produce an initiated (non-spontaneous) combustion or explosion causing a targeted damaging of the electronic device. The power required to initiate the battery combustion may be derived entirely from the battery itself such that no external power source is required. Moreover, there is no need to reduce the payload or cargo size or weight of the device, since the combustion source is the battery that is normally used to power the device, thereby eliminating the need to sacrifice features of the device (for example, the range of a drone device) in order to provide a mechanism for targeted damaging of the device to protect confidential information or material contained onboard.

The following table provides experimental results of the disclosed embodiments applied to different battery types under different conditions.

Table 1

Reference is now made to Figure 5, which is a flow diagram of a method for initiating a combustion of a rechargeable lithium battery powering an unmanned electronic device, operative in accordance with an embodiment of the present invention. In procedure 182, a trigger event is detected for initiating combustion of a rechargeable lithium battery powering an unmanned electronic device. Referring to Figure 1 , an initiated combustion of battery 124 of electronic device 120 is triggered by a trigger event, such as the receipt of an activation signal 117 from an external activator 115, or the detection of at least one initiation condition in accordance with preloaded instructions in device 120 or following receipt of an activation signal 1 17. The initiation condition may include a scheduled time, an unauthorized detection or accessing of device 120, at least one environmental condition; and/or at least one parameter of battery 124.

In procedure 183, a state of a selected initiation cell of the lithium batters is altered to cause an internal short circuit in the initiation cell, triggering a thermal runaway process and combustion of the battery. The state of the initiation cell may be altered by modifying at least one electrical property or thermal property thereof. Referring to Figure 1 , cell state regulator 126 modifies a property of initiation cell 124i of battery 122 to alter its state, responsive to the detected triggering event. The initiation cell state alteration may be implemented through various modalities. In a first example (sub-procedure 184), the initiation cell is heated with a heating element using electrical energy extracted from cells in the battery. Referring to Figure 2, a proximal heating element 136 applies heat to initiation cell 134i, causing an internal short circuit in initiation cell 134i triggering thermal runaway and combustion. The operation of heating element 136 is powered by electrical energy extracted from cells 134 of battery 132 (which may include energy derived from initiation cell 134i itself). The operating voltage of the heating element may be scaled to the voltage of the cells from which the electrical energy is derived. In a second example (sub-procedure 185), the initiation cell undergoes overcharging. Referring to Figure 1 , cell state regulator 126 overcharges initiation cell 124i such as by delivering a constant current to initiation cell 124i, to cause an internal short circuit triggering thermal runaway and combustion. In another example (subprocedure 186), a reverse polarity is applied to the initiation cell. Referring to Figure 1 , cell state regulator 126 applies a reverse polarity to initiation cell 124i to trigger thermal runaway, such as by fully discharging initiation cell 124i (e.g., via an external resistor) and then recharging initiation cell 124i with the polarities reversed. In a further example (sub-procedure 187), an external short circuit is applied to the initiation cell. Referring to Figure 1 , cell state regulator 126 applies an external short circuit to initiation cell 124i to cause an internal short circuit triggering thermal runaway and combustion, such as by connecting the positive and negative cell terminals to an external resistor. In yet a further example (subprocedure 188), the initiation cell undergoes forced discharging. Referring to Figure 1 , cell state regulator 126 applies a forced discharge to initiation cell 124i to a low or negative voltage, to cause an internal short circuit triggering thermal runaway and combustion.

Due to the modified property and altered state thereof, initiation cell 124i undergoes internal defects causing an internal short circuit leading to thermal runway and cell combustion. The combustion of initiation cell 124i propagates to adjoining cells 124 of battery 122 which in turn propagates to further cells 124, leading to combustion (and/or explosion) of battery 122 and resulting in a targeted damaging of device 120 for rendering confidential information or material contained in device 120 unusable, undecipherable, and/or inaccessible. While certain embodiments of the disclosed subject matter have been described, so as to enable one of skill in the art to practice the present invention, the preceding description is intended to be exemplary only. It should not be used to limit the scope of the disclosed subject matter, which should be determined by reference to the following claims.