Trigger unit for triggering thermal runaway in battery

Abstract

A system for testing thermal runaway in a battery cell includes a first layer of first dielectric material at least partially wrapping the battery cell, and a wire at least partially wrapping the first layer of first dielectric material. The system also includes a second layer of a second dielectric material at least partially wrapping the wire, and a power source configured to supply power to the wire. In one example, the first layer of the first dielectric material includes a polyimide film and the second layer of the second dielectric material includes mica. The system also includes a temperature sensor in contact with the first layer, the second layer, and / or the battery cell. The controller is to receive a temperature reading from the temperature sensor and to control power provided by the power source to the wire based at least in part on the temperature reading.

Description

Technical Field

[0001] This disclosure relates generally to battery technology, and more specifically to techniques for testing thermal runaway in battery packs. Background Technology

[0002] A battery is a common power source, for example, providing direct current (DC) to a load. A battery has a positive terminal (cathode) and a negative terminal (anode). Multiple batteries can be connected in series and / or in parallel to form a high-voltage and / or high-power DC power source.

[0003] Rechargeable batteries can be charged and discharged, and this charge-discharge cycle can occur multiple times throughout the battery's lifespan. For example, once a battery is discharged during use, it can be charged using an applied current, during which the original components of the battery electrodes can be fully or at least partially restored by a reverse current. Examples of such rechargeable batteries include lead-acid batteries and lithium-ion batteries.

[0004] Batteries have a wide range of applications, including consumer electronics, wearable devices, computers, electric and non-electric vehicles, and / or many other devices or systems that use DC power. However, some challenging issues remain in operating battery packs. Attached Figure Description

[0005] Figure 1 A flowchart is shown of a method for forming a triggering unit to trigger or cause thermal runaway in a battery cell according to an embodiment of the present disclosure, and a method for operating the triggering unit.

[0006] Figure 2A , Figure 2B , Figure 2C , Figure 2D1 , Figure 2D2 , Figure 2E1 , Figure 2E2 , Figure 2F1 , Figure 2F2 , Figure 2G1 , Figure 2G2 , Figure 2H1 , Figure 2H2 and Figure 2I Together, embodiments according to this disclosure are illustrated. Figure 1 The method is a triggering unit at each stage of formation and operation.

[0007] Figure 3A The illustration depicts an embodiment according to the present disclosure during operation. Figure 2I The curve showing the temperature change over time when the trigger unit is activated.

[0008] Figure 3B Embodiments according to this disclosure are shown. Figure 2IA graph showing the power variation of the heating wire supplied to the trigger unit during operation.

[0009] The accompanying drawings are for illustrative purposes only and are not necessarily drawn to scale. Various variations, configurations, and other embodiments will be understood through the following detailed description. Summary of the Invention

[0010] This invention discloses a method and system for forming and operating a triggering unit capable of inducing thermal runaway in a battery cell. Inducing thermal runaway in a battery cell allows for testing of the battery cell during a thermal runaway event. Such testing may include, for example, measuring parameters related to thermal runaway in the battery cell, and evaluating the thermal runaway handling capability of the battery cell. This triggering unit can be advantageously used to test lithium-ion battery cells, although the battery cell under test can be other types, such as lead-acid battery cells or hydrogen fuel cell cells.

[0011] In one embodiment, a system for testing thermal runaway in a battery cell includes a trigger unit comprising a first layer of a first dielectric material at least partially enclosing the battery cell, and a wire at least partially enclosing the first layer of the first dielectric material. In one example, the wire comprises one or more metals. For example, the wire is a chromium alloy wire comprising a nickel-chromium alloy. Various example layouts of the wire around the first layer of the first dielectric material will be described below. The system also includes a second layer of a second dielectric material at least partially enclosing the wire, and a power source for supplying power to the wire. In one example, the power source is configured to supply power to the wire, thereby heating the wire and causing thermal runaway in the battery cell. In one example, the first layer of the first dielectric material comprises a polyimide film, and the second layer of the second dielectric material comprises mica. In one example, the second layer of the second dielectric material has a lower thermal conductivity than the first layer of the first dielectric material.

[0012] In one embodiment, the system further includes a temperature sensor in contact with at least one of the first layer, the second layer, and the battery cell. In some examples, a controller is configured to receive temperature readings from the temperature sensor and, at least in part, control the power supplied by the power source to the conductors based on those temperature readings. In some such examples, the controller is configured to control the power supplied by the power source to the conductors to maintain a constant or near-constant rise in the temperature reading. Many variations and implementations will be apparent in light of this disclosure. Detailed Implementation

[0013] General Overview

[0014] As mentioned above, several significant challenges remain regarding the operation of battery packs, such as lithium-ion battery packs. One major challenge of lithium-ion battery technology is thermal management. A persistent concern is the potential for thermal runaway in lithium-ion batteries during use, handling, and / or transportation. Thermal runaway occurs when a series of self-sustaining exothermic side reactions lead to complete battery failure, and in some cases, even fire and / or explosion. A battery cell experiencing thermal runaway may eject jets of hot gases, flames, and high-speed molten particulate matter (called ejecta). Due to the chemical nature of lithium-ion technology, lithium-ion batteries are susceptible to thermal runaway. Despite significant progress over time in improving battery performance (e.g., reducing capacity decay, increasing usable power, etc.), the challenges of thermal runaway and its propagation remain. For example, the materials and structure of a single battery cell or battery pack can lead to localized hot spots or overheating, resulting in battery failure. Furthermore, over-constraining battery cells can cause large pressure gradients, leading to the failure of mechanical components (e.g., plates and fasteners surrounding the battery cell). Similarly, preventing ejecta from escaping can cause localized hot spots to form instantaneously, triggering thermal runaway in nearby battery cells. Therefore, thermal runaway testing of the battery pack is necessary.

[0015] Therefore, this paper describes a technique for forming a triggering unit capable of triggering or causing thermal runaway in a battery cell. In one example, triggering thermal runaway in a battery cell allows for testing and / or measurement of parameters related to thermal runaway during a thermal runaway event, and allows for testing the thermal runaway handling capability of the battery cell. For example, the triggering unit is used to test the safety and robustness of the battery cell during a thermal runaway event. The battery cell for which the thermal runaway triggering mechanism is formed can be any suitable type of battery cell, such as a lithium-ion battery cell, a lead-acid battery cell, or a hydrogen fuel cell cell.

[0016] In one example, the trigger unit includes a first dielectric material that is at least partially wrapped around one or more sides of the battery cell. For example, in the orientation shown in the figures below, the top surface of the battery cell includes a cathode, the bottom surface of the battery cell includes an anode, and one or more sides (e.g., wrapped with the first dielectric material) extend from the top surface to the bottom surface, for example, as... Figure 2AAs shown. In one example, a first dielectric material is wrapped around the side of the battery cell using a suitable adhesive. In one example, the first dielectric material has a relatively low electrical conductivity and a relatively high thermal conductivity. For example, as described below, a wire is wrapped around the first dielectric material, and the low electrical conductivity ensures that adjacent turns of the wire are not short-circuited by the first dielectric material. In one example, the aim is to allow heat generated by the wire to reach the battery cell, for example, thereby heating the battery cell and triggering thermal runaway in the battery cell. Therefore, in one example, the first dielectric material has a relatively high thermal conductivity, for example, thereby allowing heat from the wire to reach the battery cell, as described below. In one example, the first dielectric material is capable of withstanding high temperatures, such as at least 300°C, at least 400°C, at least 500°C, or at least 600°C, without significant melting. The ability to withstand high temperatures prevents or at least reduces the possibility that the dielectric material will melt during the heating of the battery cell, thereby triggering thermal runaway. In one example, the first dielectric material is an insulating tape, such as a polyimide film, for example... adhesive tape.

[0017] In one implementation, a wire is applied to and around a first dielectric material, wherein the wire meanders around the first dielectric material and at least partially wraps around it. In one example, the wire is secured to the first dielectric material using a suitable adhesive. Various example layouts of the wire will be described below. For example, the layout described below... Figure 2D1 An example first layout of the wires is shown, while the following description... Figure 2D2 An example second layout of the wires is shown.

[0018] In one example, the lead or end of the wire extends from near the bottom surface of the battery cell, including the anode. For example, during a malfunction of the battery cell (e.g., during thermal runaway or for other reasons), the battery cell may release gas, referred to herein as a “venting” of the battery cell. For example, a pressure relief valve or diaphragm may be located on or near the cathode or positive terminal of the battery cell, such as on or near the top surface of the battery cell, where, during such a venting event, the pressure relief valve or diaphragm may rupture, thereby releasing such gas. For example, a venting event may occur during thermal runaway triggered by a triggering unit. Since such gas is vented from or near the top surface of the battery cell, the end of the wire extends from or near the bottom surface of the battery cell, including the negative or positive terminal, as... Figure 2D1 and Figure 2D2As shown, for example, this avoids or reduces the chance of the wire end coming into contact with the exhaust gas. In one embodiment, the wire comprises a conductive material with relatively high resistivity, thereby enabling the wire to generate sufficient heat to trigger thermal runaway in the battery cell. Therefore, the wire acts as a heating element in the triggering unit. In one example, a nickel-chromium alloy wire can be used, wherein the nickel-chromium alloy comprises, for example, an alloy of nickel, chromium, and / or one or more other metals.

[0019] In one implementation, the temperature sensor is connected to the triggering unit. In one example, the temperature sensor is led out from near the bottom surface of the battery cell, including the anode, for example, because venting events may occur on the top surface of the battery cell, as described above. In one example, a thermocouple (e.g., a 30-gauge thermocouple) is used as the temperature sensor, but any other suitable type of temperature sensor may also be used.

[0020] In one example, a second dielectric material is used to wrap at least a portion of one or more sides of the battery cell. Thus, the second dielectric material wraps around and holds the wires in place. In one example, the second dielectric material has a relatively low thermal conductivity. For example, the thermal conductivity of the second dielectric material is lower than that of the first dielectric material. The low thermal conductivity of the second dielectric material ensures that most of the heat generated by the wires is trapped within the second dielectric material and transferred to the battery cell through the relatively high thermal conductivity of the first dielectric material, thereby triggering a thermal runaway process. In one example, a pressure-sensitive adhesive (PSA) backing dielectric material (e.g., PSA-backed mica) is used as the second dielectric material.

[0021] In one implementation, during trigger unit operation, a power source applies a voltage V to the trigger unit's leads, thereby generating a current I within the leads. In one example, a controller regulates the power supplied to the leads, for example, based on feedback from a temperature T measured by a temperature sensor attached to the battery cell. The power supplied to the leads heats the leads (e.g., a relatively high-resistance lead acts as a heating element), which in turn heats the battery cell and triggers thermal runaway within the battery cell. The power source can control the power supplied to the leads of the trigger unit, for example, by regulating the voltage V and / or current I applied to the leads of the trigger unit. The controller receives feedback from the temperature T from the temperature sensor and regulates the power source accordingly. For example, the controller is designed to ensure a relatively smooth rise in the battery cell's temperature T (e.g., a constant or near-constant temperature slope) and thereby regulates the power supplied to the leads. The controller is designed to maintain a constant or substantially constant rise in temperature T, for example, simulating a real-world battery cell thermal runaway state where the temperature may rise at a constant or substantially constant slope. Once the battery cell heats up to a certain point, it begins a self-heating process, indicating that thermal runaway has begun. Once the self-heating process begins, the controller reduces the power supplied to the wires and stops supplying any power in the event of thermal runaway.

[0022] According to some embodiments of this disclosure, these different methods can be used alone or in combination to test a battery cell by triggering a thermal runaway event in the battery cell. Many variations and embodiments will be apparent from the present disclosure.

[0023] As used herein, the term “about” indicates that the listed value may vary slightly, or be within acceptable tolerances, as long as such variation does not cause the process or equipment to be nonconforming. For example, for some elements, “about” may refer to a variation of ±0.1%; for others, “about” may refer to a variation of ±1% or ±10%, or any point thereof. In this document, terms defined in the singular also encompass terms defined in the plural, and vice versa.

[0024] Any range of values ​​mentioned in this document explicitly includes every value (including fractions and integers) within that range. For example, the range of “at least 50” or “at least about 50” mentioned in this document includes all integers and real numbers of 50 and above, and the range of “less than 50” or “less than about 50” mentioned in this document includes all integers and real numbers of 49 and below.

[0025] The terms “substantially” or “essentially” used in this article are also used with a negative connotation, referring to the complete or near-complete lack of an action, characteristic, attribute, state, structure, item, or result. For example, a “substantially” flat surface is either completely flat or nearly flat, such that its effect is the same as if it were completely flat.

[0026] Methodology

[0027] Figure 1 A flowchart of a method 100 for forming a triggering unit 200 according to an embodiment of the present disclosure to trigger or cause thermal runaway in a battery cell 204 is shown, and the operation of the method is described. Figure 2A , Figure 2B , Figure 2C , Figure 2D1 , Figure 2D2 , Figure 2E1 , Figure 2E2 , Figure 2F1 , Figure 2F2 , Figure 2G1 , Figure 2G2 , Figure 2H1 , Figure 2H2 and Figure 2I Together, they illustrate embodiments according to this disclosure. Figure 1 The various formation and operation stages of the trigger unit 200 in the method 100 shown are described below. Figure 1 and Figures 2A to 2I .

[0028] As described above, the triggering unit 200 is used to trigger thermal runaway in the battery cell, for example, to test the battery cell and / or measure parameters related to thermal runaway in the battery cell during a thermal runaway event. For example, one challenge of battery technology (e.g., lithium-ion battery technology) is thermal management. A persistent concern is the possibility of thermal runaway occurring in batteries (e.g., lithium-ion batteries) during use, handling, and / or transportation. Thermal runaway occurs when a series of self-sustaining exothermic side reactions cause the battery cell to fail completely, and in some cases, trigger a fire and / or explosion. A battery cell experiencing thermal runaway may eject hot gases, flames, and high-speed molten particulate ejecta (referred to as ejecta). Due to the chemical properties of lithium-ion technology, lithium-ion batteries are susceptible to thermal runaway. For example, the materials and structure of a single battery cell or battery pack may cause localized hot spots or overheating, leading to battery cell failure. Furthermore, over-constraining a battery cell can result in large pressure gradients, leading to failure of mechanical components (e.g., plates and fasteners surrounding the battery cell). Similarly, preventing ejecta from escaping can cause localized hot spots to form instantaneously, which can trigger thermal runaway in nearby battery cells.

[0029] therefore, Figure 1Method 100 describes an example process for triggering thermal runaway in a battery cell, for example, to test the thermal runaway handling capability of such a battery cell. For example, as described below, triggering unit 200 is used to test the safety and robustness of thermal runaway in a battery cell. Triggering unit 200 is a triggering mechanism for triggering thermal runaway in a battery cell, for example, to test the temperature at which thermal runaway occurs, to test whether the battery cell can withstand a specific temperature, and / or to test one or more other parameters (for example) related to thermal runaway in battery cell 204.

[0030] At 104 of method 100, at least a portion of one or more sides 207 of the battery cell 204 is wrapped with a first layer of dielectric material 212. In one example, the dielectric material 212 has a relatively high thermal conductivity (e.g., compared to the thermal conductivity of the dielectric material 250 described below). In one example, the top surface 205 of the battery cell 204 includes a cathode, the bottom surface 206 of the battery cell 204 includes an anode, and one or more sides 207 extend from the top surface 205 to the bottom surface 206, for example, as... Figure 2A As shown.

[0031] exist Figure 2A In the example, battery cell 204 is cylindrical. Therefore, battery cell 204 has a single side 207 extending between top surface 205 and bottom surface 206. However, in other examples, battery 204 can have other shapes. For example, the top surface 205 and bottom surface 206 of battery cell 204 can be square, rectangular, triangular, or elliptical. In some such examples, multiple sides can extend between the top and bottom surfaces. More generally, battery cell 204 can have appropriate dimensions and can have any suitable shape or specification, depending on the specific application.

[0032] In one embodiment, battery cell 204 can be any suitable type of battery cell. For example, battery cell 204 can be a lithium-ion battery cell, but it can also be other suitable types, such as a lead-acid battery cell or a hydrogen fuel cell cell. In one embodiment, battery cell 204 contains an electrolyte located within a corresponding container, although... Figure 2A The electrolyte is not shown. The battery cell can be housed within a casing, such as a plastic or metal casing. In addition to the battery cell 204, such a casing may also house or contain other components.

[0033] Figure 2B An example of the first layer of dielectric material 212 adjacent to the battery cell 204 is shown, and Figure 2CA first layer of dielectric material 212 is shown enclosing the side 207 of the battery cell 204. In one example, the dielectric material 212 is attached to the side 207 by an adhesive. In one example, the dielectric material 212 is an insulating tape or a polyimide film, for example... Adhesive tape. In some cases, the first layer of dielectric material 212 completely covers the side 207, while in other cases, the first layer of dielectric material 212 may only partially cover the side 207 (e.g., almost covering most of the middle portion of the side 207, but not covering the ends near 205 and 206). In still other cases, the first layer of dielectric material 212 may cover the side 207 in a barbershop-style manner, thereby alternating between covered and uncovered portions of the side 207.

[0034] In one example, the thermal conductivity of the dielectric material 212 is at least 0.3 W / mK (watts per meter-K), or at least 0.4 W / mK, at least 0.6 W / mK, at least 0.8 W / mK, or at least 1 W / mK. Therefore, heat can be transferred to the battery cell under test through the first dielectric material 212, as will be explained below.

[0035] In one example, the dielectric material 212 is capable of withstanding high temperatures, such as at least 300°C, at least 400°C, at least 500°C, or at least 600°C, without substantially melting. In one example, this high-temperature resistance prevents or at least reduces the likelihood of the dielectric material 212 melting during thermal runaway of the battery cell 204. Furthermore, the dielectric material 212 will prevent short circuits in the heating wire used subsequently, as described below.

[0036] It should be noted that during normal or routine operation of battery cell 204 or other parts of battery cell 204, dielectric material 212 does not encapsulate battery cell 204. Instead, dielectric material 212 encapsulates battery cell 204 to form trigger unit 200 and to test whether battery cell 204 has experienced thermal runaway.

[0037] The dielectric material 212 offers numerous benefits. For example, it forms both a thermal pathway to the battery cell 204 and an electrical barrier layer between the battery cell 204 and the subsequently added heating wire 220. This allows heat from the heating wire 220 to be effectively transferred to the battery cell 204 due to the relatively high thermal conductivity of the dielectric material 212, and prevents short circuits in the coil of the heating wire 220 due to its electrical insulating properties. Therefore, for example, if any outer layer or layer of the battery cell 204 melts during testing, the first dielectric material 212 prevents short circuits between the molten material and portions of the subsequently added heating wire, such as in… Figure 1 As stated in 108 places.

[0038] Then, method 100 proceeds from 104 to 108. At 108, a wire 220 is applied to and around the first dielectric material 212, the wire 220 meandering around the dielectric material 212 and at least partially enclosing the first dielectric material 212. In one example, the lead or end of the wire 220 extends from near the bottom surface 206 of the battery cell 204, which includes the anode. In one example, the wire 220 is secured to the first dielectric material 212 using adhesive or other suitable fasteners.

[0039] Figure 2D1 An example shape of a wire 220a wrapped in dielectric material 212 is shown, and Figure 2D2 Another example shape of the wire 220b wrapped in dielectric material 212 is shown. (Reference) Figure 2D1 The wire 220a has ends or leads 221a and 222a that extend from near the bottom surface 206, which includes the negative or anode terminal of the battery cell 204. Therefore, the ends 221a and 222a are closer to the anode of the battery cell than to the cathode.

[0040] When a battery cell malfunctions (e.g., thermal runaway or other causes), the battery cell may release gases, referred to herein as "venting" of the battery cell. For example, a pressure relief valve or diaphragm may be located on or near the cathode or positive terminal of battery cell 204, such as on or near the top surface of battery cell 204, where, in such a venting event, the pressure relief valve or diaphragm may rupture, thereby releasing these gases. For example, a venting event may occur during thermal runaway triggered by triggering unit 200. Because these gases are vented from or near the top surface of battery cell 204, the ends of the wires or leads 221a and 222a extend from or near the bottom surface 206, which includes the negative or positive terminal of battery cell 204, as shown below. Figure 2D1 As shown, for example, this avoids or reduces the chance of leads 221a and 222a coming into contact with the exhaust gas.

[0041] like Figure 2D1 As further shown, the conductor 220a includes multiple extension portions 216 and multiple loop portions 225. For example, the extension portions 226 extend from near the bottom surface 206 (e.g., anode) of the battery cell 204 to the top surface 205 (e.g., cathode) of the battery cell 204. Near the top surface 205, the conductor 220a folds back or turns at the loop portions 225 and now extends from near the top surface 205 of the battery cell 204 to the bottom surface 206 of the battery cell 204. This extension and looping of the conductor 220a continues, such that the conductor 220a covers a large area of ​​the dielectric material 212.

[0042] In one example, at or near the loop portion 225, the ends of the respective extensions are attached to the first layer of dielectric material 212 using dielectric material tape 224 (e.g., which may be the same as or different from dielectric material 212). For example, Figure 2D1 A magnified view of a portion of wire 220a is further shown, along with two examples of such tape 224. Tape 224 secures wire 220a in place, for example, by attaching wire 220a to dielectric material 212. In another example, other suitable methods may be used to secure wire 220a in place relative to dielectric material 212.

[0043] Now for reference Figure 2D2 This illustrates another example shape of the wire 220b wrapped in dielectric material 212. Figure 2D1 Similar to the example shown, Figure 2D2 The wire 220b shown has ends or leads 221b and 222b that extend from near the bottom surface 206 and include the negative or anode terminals of the battery cell 204. The above description regarding lead positioning and venting also applies here.

[0044] like Figure 2D2 As further shown, the wire 220b includes a vertical spiral shape or a spring shape and is wrapped around the battery cell 204. For example, the wire 220b starts from end 221b and forms multiple loops around the battery cell 204, extending from the bottom surface 206 near the bottom surface 206 of the battery cell 204 to the top surface 205, as shown. When the loop reaches the top surface 205 near the bottom surface 206 of the battery cell 204, a portion 229 of the wire 220b extends from the top surface 205 near the bottom surface 206 of the battery cell 204 to end 222b near the bottom surface 206 of the battery cell 204.

[0045] In one embodiment, to prevent a short circuit between portion 229 of conductor 220b and the coil of conductor 220b, portion 229 of conductor 220b and the coil of conductor 220b are separated by dielectric material tape 228, such as polyimide film tape. adhesive tape. Figure 2D2 The tape 228 is shown as semi-transparent, thus revealing the coil of the wire 220b beneath the tape 228, although in the actual implementation of the trigger unit 200, the tape 228 may not be semi-transparent (for example).

[0046] In one embodiment, wires 220a and / or 220b comprise a conductive material with relatively high resistivity, such that when current flows through wires 220a and / or 220b, wires 220a and / or 220b can generate sufficient heat, or otherwise apply heat to wires 220a and / or 220b, thereby triggering thermal runaway in battery cell 204. In one example, nichrome wire may be used.

[0047] Nickel-chromium alloys comprise a range of alloys, such as nickel and chromium, and / or may also contain iron. In some examples, nickel-chromium alloys may also contain one or more other elements. Nickel-chromium alloys are also known as NiCr, nickel-chromium, or nickel-chromium. Nickel-chromium alloys can be used as resistance wires in heating applications, such as as heating elements. For example, a nickel-chromium alloy contains 80% nickel and 20% chromium by weight, although other combinations of nickel and chromium (and / or one or more other metals) are also possible. In one example, the resistivity of wires 220a and / or 220b is, for example, at least 80 μΩ-cm, or at least 100 μΩ-cm, or at least 110 μΩ-cm. In one example, 30 gauge nickel-chromium alloy wire can be used. In another example, fine copper wire and / or other suitable wires that can be used as heating elements may also be used.

[0048] Figure 2D1 and Figure 2D2 Two example layouts of the conductor are shown, although conductor 220 can be arranged in many other ways, for example, as long as conductor 220 at least partially covers dielectric material 212 and is capable of heating battery cell 204. In another example, conductor 220 can be replaced by other suitable heating devices. For example, a flexible printed circuit board (PCB) containing a heating element can be used instead of conductor 220. For example, the flexible PCB can cover dielectric material 212 and battery cell 204. In one example, conductive traces on the flexible PCB can act as heating elements to heat the battery cell.

[0049] Refer again Figure 1 Method 100 proceeds from 108 to 112. At 112, a temperature sensor 230 is attached to the trigger unit 200. In one example, the temperature sensor 230 extends from near the bottom surface 206 of the battery cell 204, which includes the anode, for example, where an venting event may occur on the top surface 205 of the battery cell 204 as described above. In one example, a thermocouple (e.g., a 30-gauge thermocouple) is used as the temperature sensor, but any other suitable type of temperature sensor may also be used.

[0050] For example, Figure 2E1 An example location of the temperature sensor 230 is shown for the wire 220a. Figure 2E2An example location of the temperature sensor 230 on the wire 220b is shown. In one example, the temperature sensor 230 may be located on the bottom surface 206 of the battery cell 204, as shown. Figure 2E2 As shown. Therefore, the temperature sensor 230 can be connected to the battery cell 204 (e.g., Figure 2E2 (as shown), dielectric material 212 and dielectric material 250 (described below) are one or more contacts.

[0051] In one example, dielectric tape 231 can be adhered to the ends 221, 222 of the wires and the ends of the thermocouple 230, for example, thereby fixing the ends 221, 222 of the wires and the ends of the thermocouple 230 (e.g., so that they do not move significantly relative to each other), thereby reducing the possibility of accidental short circuits between them, such as... Figure 2F1 and Figure 2F2 As shown. Tape 231 can be any suitable tape, such as polyimide film tape, for example... adhesive tape.

[0052] Refer again Figure 1 Method 100 proceeds from 112 to 116. At 116, at least a portion of one or more sides of the battery cell 204 is wrapped with a second dielectric material 250, such that the wire 220 is located between the first dielectric material 212 and the second dielectric material 250. For example, Figure 2G1 A second dielectric material 250 is shown adjacent to the battery cell 204, which includes wire 222a, and... Figure 2G2 A second dielectric material 250 is shown encapsulating a battery cell 204 including wire 222a. Similarly, Figure 2H1 A second dielectric material 250 is shown adjacent to the battery cell 204, which includes wire 222b, and... Figure 2G2 The second dielectric material 250 is shown encapsulating the battery cell 204, which includes the wire 222b.

[0053] exist Figure 2G2 and Figure 2H2 In this example, dielectric material 250 is shown as semi-transparent, thus revealing the wires and thermocouples beneath it. However, in the actual implementation of trigger unit 200, dielectric material 250 may not be semi-transparent in one example.

[0054] In one example, dielectric material 250 has a relatively low thermal conductivity. For example, the thermal conductivity of dielectric material 250 is less than that of dielectric material 212. The low thermal conductivity of dielectric material 250 ensures that most of the heat generated by wires 220a and / or 220 is trapped or conducted inward and transferred to the battery cell 204 through the relatively high thermal conductivity of the first dielectric layer 212. Therefore, the second dielectric layer 250 acts as a thermal barrier, thereby preventing or reducing the escape of heat from wires 220 from the battery cell 204 and firmly securing wires 220 in place.

[0055] In one example, dielectric material 250 employs a pressure-sensitive adhesive (PSA) backing dielectric material, thereby enabling dielectric material 250 to easily encapsulate battery cell 250. An exemplary material is mica, such as PSA-backed mica. For example, the thermal conductivity of dielectric material 250 (e.g., perpendicular to the plane of dielectric material 250) may be, for example, at most 0.2 W / mK, or at most 0.3 W / mK, or at most 0.5 W / mK, or at most 1 W / mK, or at most 2 W / mK. For example, the thermal conductivity of muscovite (e.g., perpendicular to the plane of the mica sheet) is approximately 0.3 W / mK. As described above, for example, the thermal conductivity of dielectric material 250 is less than the thermal conductivity of dielectric material 212.

[0056] In some cases, the second dielectric layer 250 completely covers the conductor 220 and the underlying first dielectric layer 212, while in other cases, the second dielectric layer 250 may only partially cover the conductor 220 and / or the underlying first dielectric layer 212. As mentioned above, one benefit of the second dielectric layer 250 is that it traps heat, thereby inducing thermal runaway in the battery cell under test, so complete coverage is helpful for this.

[0057] Figure 2G2 and / or Figure 2H2 The final system 200 is a trigger unit that can be used to test the thermal runaway of the battery cell 204. Figure 2G2 or Figure 2H2 Any of the triggering units in the circuit can be used, the difference between these two triggering units being the way the wire 220 wraps around the battery unit 204. As described above, Figures 2A to 2H2 Two example ways in which the wire 220 is wrapped around the battery cell 204 are shown, but in another example, the wire 220 may also be wrapped in other suitable ways.

[0058] Therefore, procedures 104, 108, 112, and 116 of method 100 describe the formation of an example triggering unit for triggering thermal runaway in battery cell 204. Subsequent procedure 120 of method 100 describes the operation of the triggering unit.

[0059] Refer again Figure 1 Method 100 proceeds from 116 to 120. In 120, a voltage V (e.g., via power supply 272) is applied to the wire 220 of the triggering unit 200 to generate a current I within the wire 220, and the controller 270 adjusts the power supplied to the wire 220 (e.g., based on feedback of the temperature T measured by a temperature sensor attached to the battery cell 204) to trigger thermal runaway in the battery cell. Figure 2I An example arrangement of controller 270 and power supply 272 is shown. Power supply 272 is capable of controlling the power supplied to the wire 220 of trigger unit 200, for example, by adjusting the voltage V and / or current I applied to the wire 220 of trigger unit 200. Controller 270 receives temperature T from temperature sensor 230 and adjusts power supply 272 based on temperature T.

[0060] Although not shown, in this example, controller 272 includes or is coupled to a communication chip, for example, for communicating with temperature sensor 230. In one embodiment, controller 270 includes a microprocessor coupled to a computer-readable storage medium (e.g., memory or data storage device). In one embodiment, the computer-readable storage medium stores instructions or code that, when executed by the microprocessor, cause the microprocessor to perform operations to regulate power supply 270 based on temperature T, as described herein. In another example, controller 270 may be implemented using suitable hardware circuitry.

[0061] In one example, the thermal runaway triggering process 120 is executed when battery cell 204 is in a non-operating state. In another example, the thermal runaway triggering process 120 is executed when battery cell 204 is in an operating state (e.g., supplying power to a load). In one example, if battery cell 204 is supplying power to a load and process 120 is executed, the operation of battery cell 204 may cause some additional heat generated by internal losses within the battery cell, in addition to the heat generated by wire 220. In another example, for example, battery cell 204 may be undergoing a charging process when the thermal runaway triggering process 120 is executed. In another example, the state of charge of battery cell 120 may be between 0% and 100% when the thermal runaway triggering process 120 is executed. Therefore, in one example, the thermal runaway triggering process 120 can be executed in any operating, non-operating, and / or charging state of battery cell 204.

[0062] Figure 3A The illustration depicts an operation according to an embodiment of the present disclosure. Figure 2I Figure 304 shows the temperature change over time of the trigger unit 200. Figure 3B The illustration depicts an operation provided during operation triggering unit 200 according to an embodiment of the present disclosure. Figure 2IThe curve 308 shows the change in power of the heating wire 220 of the trigger unit 200 over time.

[0063] Referring to curves 304 and 308, before time t0, the wire 220 of the trigger unit 200 is not energized, and the temperature T is the ambient temperature. Starting from time t0, the wire 220 of the trigger unit 200 is energized, causing the temperature T to rise. For example, since the wire 220 is a heating element with relatively high resistivity, the temperature of the wire 220 will rise with the power supplied to the wire 220.

[0064] As shown in graphs 304 and 308, controller 270 is designed to ensure a relatively smooth rise in temperature T of battery cell 204 (e.g., a constant or near-constant temperature slope), and thereby regulate the power delivered to conductor 200. Therefore, power delivery graph 308 is not smooth and has peaks and troughs. Controller 270 is designed to maintain a constant or substantially constant rise in temperature T, for example, thereby simulating a real battery cell thermal runaway state, where the temperature may rise at a constant or substantially constant slope.

[0065] At time t1 (see Figure 308), the average power increases, as the power supplied to wire 220 heats up, which in turn causes the temperature inside battery cell 204 to rise. Starting at time t1, controller 270 begins to reduce the average power, for example, because battery cell 204 begins a self-heating process from time t1, indicating that thermal runaway has begun. Self-heating continues until time t2, and the power gradually decreases from time t1 to time t2. At time t2, thermal runaway occurs inside battery cell 204, and the temperature T suddenly rises.

[0066] Please note that, for ease of description, Figure 1 The various processes in method 100 are displayed in a specific order. However, according to some implementations, one or more processes may be executed in a different order, or not at all (and are therefore optional). Given this disclosure, numerous variations of method 100 and the techniques described herein will become apparent.

[0067] Further exemplary implementations

[0068] The following examples illustrate further implementations, from which various arrangements and configurations can be clearly seen.

[0069] Example 1. A system for testing thermal runaway in a battery cell, comprising: a first layer of a first dielectric material that at least partially encapsulates the battery cell; a wire comprising one or more metals that at least partially encapsulates the first layer of the first dielectric material; a second layer of a second dielectric material that at least partially encapsulates the wire; and a power source configured to supply power to the wire.

[0070] Example 2. The system according to Example 1 further includes: a temperature sensor in contact with the first layer, the second layer and / or the battery cell.

[0071] Example 3. The system according to Example 2 further includes: a controller configured to receive temperature readings from the temperature sensor and to control the power supplied to the conductor by the power source based at least in part on the temperature readings.

[0072] Example 4. The system according to Example 3, wherein the controller is configured to control the power supplied to the conductor by the power source, wherein the power supplied to the conductor generates heat, and wherein the controller controls the power source such that the temperature reading from the temperature sensor maintains a substantially constant rate of change.

[0073] Example 5. A system according to any one of Examples 3 to 4, wherein the controller is configured to stop the power supply or reduce the amount of power supplied to the wire in response to thermal runaway triggered in the battery cell.

[0074] Example 6. A system according to any one of Examples 1 to 5, wherein the power source is configured to supply power to the wire, thereby heating the wire and causing thermal runaway in the battery cell.

[0075] Example 7. A system according to any one of Examples 1 to 6, wherein the wire includes: a first extension portion extending from near the anode of the battery cell to near the cathode of the battery cell; a second extension portion extending from near the cathode of the battery cell to near the anode of the battery cell; and a loopback portion connecting the first extension portion and the second extension portion.

[0076] Example 8. A system according to any one of Examples 1 to 7, wherein the wire has a first end and a second end, the first end and the second end being close to the anode of the battery cell and away from the cathode of the battery cell.

[0077] Example 9. A system according to any one of Examples 1 to 8, wherein: the wire is arranged in a vertical spiral around the battery cell; the vertical spiral has a first end near the anode of the battery cell and a second end near the cathode of the battery cell; the first end of the wire connects the first end of the vertical spiral to the power source, such that the first end of the wire is closer to the anode than the cathode; the second end of the wire connects the second end of the vertical spiral to the power source; and the second end of the wire is at least partially disposed above the vertical spiral and spaced apart from the vertical spiral by a third dielectric material.

[0078] Example 10. A system according to any one of Examples 1 to 9, wherein the conductor is a nickel-chromium alloy conductor comprising nickel and chromium.

[0079] Example 11. A system according to any one of Examples 1 to 10, wherein the second layer of the second dielectric material has a lower thermal conductivity than the first layer of the first dielectric material.

[0080] Example 12. A system according to any one of Examples 1 to 11, wherein the first layer of the first dielectric material comprises a polyimide film, and the second layer of the second dielectric material comprises mica.

[0081] Example 13. A method of forming and operating a thermal runaway triggering unit for a battery cell, the method comprising: having a first layer of a first dielectric material at least partially cover a surface of the battery cell, the surface extending from the cathode to the anode of the battery cell; having a wire at least partially cover the first layer of the first dielectric material; having a second layer of a second dielectric material at least partially cover the wire; and connecting the wire to a power source.

[0082] Example 14. The method according to Example 13 further includes: arranging a temperature sensor in contact with at least one of the first layer, the second layer, and the battery cell.

[0083] Example 15. The method according to any one of Examples 13 to 14 further includes: supplying power from the power source to the wire, thereby heating the wire and causing thermal runaway in the battery cell.

[0084] Example 16. The method according to any one of Examples 13 to 15 further includes: arranging a temperature sensor in contact with at least one of the first layer, the second layer, and the battery cell; supplying power from the power source to the wire, thereby heating the wire and causing thermal runaway in the battery cell; and regulating the power from the power source to the wire based at least in part on the output of the temperature sensor.

[0085] Example 17. According to the method of Example 16, wherein adjusting the power from the power source to the wire includes: adjusting the power from the power source to the wire such that one or both of the following (i) at least a portion of the temperature rise has a constant or nearly constant slope, and (ii) in response to thermal runaway in the battery cell, reducing or removing the power source.

[0086] Example 18. A system for testing a battery cell, comprising: a wire including one or more metals, at least partially enclosing the battery cell; an electrical barrier layer located between the wire and the battery cell; and a thermal barrier layer located on the wire.

[0087] Example 19. The system according to Example 18 further includes: a thermocouple for measuring the temperature rise of the battery cell.

[0088] Example 20. The system according to Example 19 further includes: a power source for supplying power to the conductor; and a controller for regulating the power supplied to the conductor based at least in part on temperature readings from the thermocouple.

[0089] The foregoing description of exemplary embodiments is for illustrative and descriptive purposes only. It is not intended to be exhaustive or to limit this disclosure to the precise form disclosed. Various modifications and variations are possible in light of this disclosure. The scope of this disclosure is not limited by this detailed description but by the appended claims. Future applications claiming priority to this application may assert the disclosed subject matter in different ways and may generally include any set of one or more limiting conditions disclosed or otherwise argued herein.

Claims

1. A system for testing thermal runaway in a battery cell, comprising: The first layer of first dielectric material at least partially encapsulates the battery cell; A wire, comprising one or more metals, at least partially encapsulates the first layer of a first dielectric material; A second layer of second dielectric material, which at least partially encapsulates the conductor; as well as The power supply is configured to supply power to the conductor.

2. The system according to claim 1, further comprising: Temperature sensors that are in contact with the first layer, the second layer and / or the battery cell.

3. The system according to claim 2, further comprising: A controller configured to receive temperature readings from the temperature sensor and to control the power supplied to the conductor by the power source based at least in part on the temperature readings.

4. The system according to claim 3, wherein, The controller is configured to control the power supplied to the conductor by the power source, wherein the power supplied to the conductor generates heat, and wherein the controller controls the power source such that the temperature reading from the temperature sensor maintains a substantially constant rate of change.

5. The system according to claim 3, wherein, The controller is configured to stop supplying power or reduce the amount of power supplied to the wire in response to thermal runaway triggered in the battery cell.

6. The system according to claim 1, wherein, The power supply is configured to supply power to the wire, thereby heating the wire and causing thermal runaway in the battery cell.

7. The system according to claim 1, wherein, The wire includes: a first extension portion that extends from near the anode of the battery cell to near the cathode of the battery cell; The second extension extends from near the cathode of the battery cell to near the anode of the battery cell; and The loop portion connects the first extension portion and the second extension portion.

8. The system according to claim 1, wherein, The wire has a first end and a second end, the first end and the second end being close to the anode of the battery cell and far away from the cathode of the battery cell.

9. The system according to claim 1, wherein: The wire is arranged in a vertical spiral around the battery cell; The vertical spiral has a first end near the anode of the battery cell and a second end near the cathode of the battery cell; The first end of the wire connects the first end of the vertical helix to the power source, such that the first end of the wire is closer to the anode than the cathode; The second end of the wire connects the second end of the vertical helix to the power source; and The second end of the conductor is at least partially positioned above the vertical helix and is separated from the vertical helix by a third layer of dielectric material.

10. The system according to claim 1, wherein, The conductor is a nickel-chromium alloy conductor that includes nickel and chromium.

11. The system according to claim 1, wherein, The second dielectric material of the second layer has a lower thermal conductivity than the first dielectric material of the first layer.

12. The system according to claim 1, wherein, The first dielectric material of the first layer comprises a polyimide film, and the second dielectric material of the second layer comprises mica.

13. A method for forming and operating a thermal runaway triggering unit for a battery cell, the method comprising: The first layer of first dielectric material at least partially covers the surface of the battery cell, the surface extending from the cathode to the anode of the battery cell; The conductor is at least partially wrapped around the first layer of the first dielectric material; The second layer of the second dielectric material at least partially encapsulates the conductor; and Connect the wire to the power source.

14. The method of claim 13, further comprising: A temperature sensor is arranged to contact at least one of the first layer, the second layer, and the battery cell.

15. The method of claim 13, further comprising: Power is supplied to the wire from the power source, thereby heating the wire and causing thermal runaway in the battery cell.

16. The method of claim 13, further comprising: A temperature sensor is arranged to contact at least one of the first layer, the second layer, and the battery cell; Power is supplied to the wire from the power source, thereby heating the wire and causing thermal runaway in the battery cell; and The power from the power source to the conductor is regulated at least in part based on the output of the temperature sensor.

17. The method according to claim 16, wherein, Adjusting the power from the power source to the conductor includes: The power from the power source to the wire is adjusted such that one or both of the following occur: (i) at least a portion of the temperature rise has a constant or nearly constant slope, and (ii) in response to thermal runaway in the battery cell, the power source is reduced or removed.

18. A system for testing battery cells, comprising: A wire, comprising one or more metals, at least partially encapsulates a battery cell; An electrical barrier layer is located between the conductor and the battery cell; as well as A thermal barrier layer located on the conductor.

19. The system of claim 18, further comprising: Thermocouples used to measure the temperature rise of the battery cell.

20. The system of claim 19, further comprising: A power source, which supplies power to the conductor; as well as A controller for adjusting the power supplied to the conductor based at least in part on temperature readings from the thermocouple.

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