EP4720572A1 - Systems and methods for testing a substrate's response to thermal runaway of a battery - Google Patents

Abstract

A system for testing the response of a substrate to thermal runaway of a battery can comprise a nozzle defining one or more openings at an exit of the nozzle, a first conduit configured to direct gas and fuel to the nozzle such that the gas and fuel flow through each of the opening(s) of the nozzle, and a second conduit configured to direct grit from the grit supply out of the nozzle.

Description

SYSTEMS AND METHODS FOR TESTING A SUBSTRATE’S RESPONSE TO THERMAL RUNAWAY OF A BATTERY

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to European Patent Application No. 23176112.3, filed May 30, 2023, the entire contents of which are incorporated herein by reference.

FIELD OF INVENTION

[0002] The present invention relates generally to systems for testing the response of a substrate to thermal runaway of a battery.

BACKGROUND

[0003] Electric vehicles are growing in popularity with the fast advances of lithium-ion battery (LIB) technology. However, one concern with electric vehicles and the batteries that they employ is fire safety. An electric vehicle’s battery may be at risk of thermal runaway when exposed to electric, thermal, and mechanical abuses. Thermal runaway is a process in which an increase in temperature of the battery causes the battery to release energy that further increases the temperature of the battery, creating a positive feedback loop that can have destructive results. When thermal runaway occurs, the battery may reach a high temperature, a fire may develop on the battery and surrounding materials, and battery cells may explode and discharge debris outward.

[0004] To protect occupants of electric vehicles from thermal runaway scenarios, batteries of electric vehicles can be encased in a material that can withstand high temperatures, fire, and debris impingement for enough time to give occupants the opportunity to safely exit the vehicle. The protective ability of a material can be assessed using a test that simulates conditions of a thermal runaway scenario. However, current tests may not subject a material to conditions that are representative of what occurs during thermal runaway of a battery, which can pose challenges for accurately assessing the material’s protective ability.

[0005] Some tests use a torch to generate a flame to test a material’s flame retardancy. However, those tests do not simulate the debris impingement that can occur in a thermal runaway scenario. The results they produce thus may not fully reflect a material’s ability to protect occupants from thermal runaway of a battery. [0006] Other tests expose a material to high-temperature gas and particles released from the ignition of a pyrotechnic to ascertain whether the exposure will compromise the material’s integrity within a specified amount of time. But the intensity of the high-temperature gas and particles emitted from a pyrotechnic are inflexible in operating conditions, which may be too high to permit differentiation between the performances of different materials.

[0007] Finally, some tests use a sand blaster alongside a torch that generates a flame in an alternative operation to both test a material’s flame retardancy and its resilience to debris impingement. While these tests may better simulate a thermal runaway scenario than those that employ a torch alone, the grit material that the tests employ may not reach the high temperature that battery debris can reach in a thermal runaway scenario. Accordingly, the conditions produced in current torch-sand blaster combination tests may not be fully representative of what occurs during thermal runaway of a battery.

SUMMARY

[0008] The present systems can be used to test the response of a substrate to thermal runaway of a battery in a manner that better simulates thermal runaway conditions than conventional tests. Some systems can comprise a torch comprising a nozzle defining one or more openings at an exit of the nozzle, a first conduit, and a second conduit. The first conduit can be configured to direct oxidizing gas and fuel through the opening(s) of the nozzle, and the gas and fuel can be ignited to generate a partially premixed flame. The second conduit can be configured to direct grit out of the nozzle carried by gas, which can be compressed air.

[0009] The torch can be configured such that the flow of gas and fuel from the first conduit — and thus the flame generated therefrom — is concentrated about the grit to facilitate heating thereof. For example, the second conduit can have a first maximum interior transverse dimension at an exit of the second conduit and, for each of the opening(s) of the nozzle through which the gas and fuel flow, a transverse distance between a centerline of the second conduit at the second conduit’s exit and an interior surface of the nozzle that circumscribes the opening can be greater than half the first maximum interior transverse dimension while still being less than or equal to 2 times the first maximum interior transverse dimension. With the gas and fuel concentrated about the grit flowing out of the nozzle, the flame generated from the ignition of the gas and fuel can better heat the grit such that the grit can have a relatively high temperature. The substrate being tested can be exposed to the flame generated by the torch and impinged with the heated grit at conditions that are representative of those that occur during thermal runaway of a battery.

[0010] Some of the present systems for testing the response of a substrate to thermal runaway of a battery comprise a torch, and some of the present methods for testing the response of the substrate to thermal runaway of a battery using the system comprise exposing the substrate to a flame generated by the torch. The torch, in some embodiments, has an oxygencontaining gas supply and a fuel supply. In some embodiments, the torch has a nozzle defining one or more openings at an exit of the nozzle. The one or more openings of the nozzle, in some embodiments, comprise no more than 5 openings. In some embodiments, the torch comprises a first conduit configured to direct gas from the oxygen-containing gas supply and fuel from the fuel supply to the nozzle such that the gas and fuel flow through the opening(s) of the nozzle. The torch, in some embodiments, has an exit through which gas from the oxygencontaining gas supply and fuel from the fuel supply are permitted to exit the torch. The opening(s) of the nozzle, in some embodiments, define the exit of the torch. In some embodiments, the torch comprises an ignitor disposed downstream of the exit of the torch. In some methods, a maximum temperature of the flame is between 1,000 and 2,000 °C.

[0011] The torch, in some embodiments, has a grit supply, and some methods comprise impinging the substrate with grit from the grit supply. In some embodiments, the torch has a second conduit. The second conduit, in some embodiments, is configured to direct grit from the grit supply out of the nozzle. In some embodiments, an exit of the second conduit is disposed upstream of the exit of the torch. In some embodiments, the opening(s) of the nozzle and the second conduit define the exit of the torch. In some methods, the grit is at a temperature that is greater than 200 °C upon impingement of the substrate.

[0012] The second conduit, in some embodiments, has a first maximum interior transverse dimension at an exit of the second conduit through which grit from the grit supply is permitted to exit the second conduit. In some embodiments, for each of the opening(s) of the nozzle, a transverse distance between a centerline of the second conduit at the exit of the second conduit and an interior surface of the nozzle circumscribing the opening is greater than half of the first maximum interior transverse dimension and less than or equal to 2 times the first maximum interior transverse dimension. In some embodiments, the second conduit includes a linear portion. The linear portion, in some embodiments, has a second maximum interior transverse dimension and a length that is at least 50 times the second maximum interior transverse dimension. [0013] The second conduit, in some embodiments, has a first interior cross-sectional area at the exit of the second conduit and the opening(s) of the nozzle have a second interior cross- sectional area. The second interior cross-sectional area, in some embodiments, is greater than the first interior cross-sectional area and less than or equal to 30 times the first interior cross- sectional area. The exit of the torch, in some embodiments, has a third interior cross-sectional area that is from 2 to 30 times the first interior cross-sectional area. In some embodiments, the first conduit surrounds the second conduit to define a volume between the first conduit and the second conduit. The volume, in some embodiments, has a fourth interior cross-sectional area that is from 20 to 40 times the first interior cross-sectional area.

[0014] In some embodiments, the torch comprises a second gas supply. The second gas supply, in some embodiments, is in fluid communication with the second conduit such that gas is permitted to flow from the second gas supply to the second conduit. The second conduit, in some embodiments, is configured to direct the gas from the second gas supply out of the nozzle with the grit from the grit supply. In some embodiments, the second gas supply is in fluid communication with the grit supply such that gas is permitted to flow from the second gas supply to the grit supply.

[0015] In some embodiments, the system comprises a frame configured to position a substrate in front of and in fixed relation relative to the nozzle. In some embodiments, a distance between the nozzle and the substrate is between 1.25 and 50.0 centimeters.

[0016] In some methods, once begun, the impinging is performed continuously until bum- through of the substrate. In some methods, the substrate comprises a sheet of material, the sheet of material comprising a polymer.

[0017] The term “coupled” is defined as connected, although not necessarily directly, and not necessarily mechanically; two items that are “coupled” may be unitary with each other. The terms “a” and “an” are defined as one or more unless this disclosure explicitly requires otherwise. The term “substantially” is defined as largely but not necessarily wholly what is specified — and includes what is specified; e.g., substantially 90 degrees includes 90 degrees and substantially parallel includes parallel — as understood by a person of ordinary skill in the art. In any disclosed embodiment, the term “about” may be substituted with “within [a percentage] of’ what is specified, where the percentage includes 0.1, 1, 5, and 10 percent.

[0018] The terms “comprise” and any form thereof such as “comprises” and “comprising,” “have” and any form thereof such as “has” and “having,” and “include” and any form thereof such as “includes” and “including” are open-ended linking verbs. As a result, a product or system that “comprises,” “has,” or “includes” one or more elements possesses those one or more elements but is not limited to possessing only those elements. Likewise, a method that “comprises,” “has,” or “includes” one or more steps possesses those one or more steps but is not limited to possessing only those one or more steps.

[0019] Any embodiment of any of the products, systems, and methods can consist of or consist essentially of — rather than comprise/have/include — any of the described steps, elements, and/or features. Thus, in any of the claims, the term “consisting of’ or “consisting essentially of’ can be substituted for any of the open-ended linking verbs recited above in order to change the scope of a given claim from what it would otherwise be using the open-ended linking verb.

[0020] Further, a device or system that is configured in a certain way is configured in at least that way, but it can also be configured in other ways than those specifically described.

[0021] The feature or features of one embodiment may be applied to other embodiments, even though not described or illustrated, unless expressly prohibited by this disclosure or the nature of the embodiments.

[0022] Some details associated with the embodiments described above and others are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following drawings illustrate by way of example and not limitation. For the sake of brevity and clarity, every feature of a given structure is not always labeled in every figure in which that structure appears. Identical reference numbers do not necessarily indicate an identical structure. Rather, the same reference number may be used to indicate a similar feature or a feature with similar functionality, as may non-identical reference numbers.

[0024] FIG. 1A is a schematic diagram of one of the present systems for testing a substrate’s response to thermal runaway of a battery, wherein the system comprises a frame configured to hold the substrate and a torch that can direct oxy gen-containing gas, fuel, and grit toward the substrate while the substrate is held in the frame.

[0025] FIG. IB is a partial perspective view of the system of FIG. 1 A and illustrates the positioning of a nozzle of the torch relative to the portion of the frame configured to hold the substrate.

[0026] FIG. 1C is a sectional view of a burner assembly of the torch of the system of FIG.

1 A, the burner assembly including an exit of the torch. In the depicted embodiment, the burner assembly comprises the nozzle of the torch, a first conduit configured to direct oxygencontaining gas and fuel to the nozzle, and a second conduit configured to direct grit out of the nozzle, where opening(s) at the nozzle’s exit and the second conduit together define the exit of the torch.

[0027] FIG. 2 is a sectional view of a burner assembly that is usable in some of the present systems and is substantially the same as the burner assembly of FIG. 1C, except that the exit of the second conduit is disposed upstream of the exit of the torch such that the opening(s) of the nozzle alone define the exit of the torch.

[0028] FIG. 3 is a to-scale front view of a burner assembly that is usable in some of the present systems, showing a nozzle having multiple openings and a second conduit.

[0029] FIG. 4 is a partial, enlarged sectional view of the burner assembly of FIG. 1C and illustrates the relative sizing of the nozzle, the first conduit, and the second conduit.

[0030] FIG. 5A illustrates a step in one of the present methods using the system of FIG. 1A in which the substrate is exposed to a flame that the torch generates from the oxy gen-containing gas and fuel and the substrate is impinged with grit.

[0031] FIG. 5B illustrates bum-through of the substrate in some of the present methods after the impinging is performed continuously.

[0032] FIG. 6A illustrates a test conducted using the system of FIGs. 1A-1C in which a substrate was exposed to a flame generated from air and propane and was impinged by number 46 grit.

[0033] FIG. 6B is a picture of the substrate taken during the test of FIG. 5 A using an infrared camera and illustrates a temperature of the portion of the substrate exposed to the flame.

[0034] FIG. 7A illustrates simulated temperatures of a flame generated using one of the present torches.

[0035] FIG. 7B illustrates simulated velocities of gas exiting the nozzle of the torch of FIG. 7A.

[0036] FIG. 7C illustrates simulated velocities of grit exiting the nozzle of the torch of FIG. 7A.

[0037] FIG. 7D illustrates simulated temperatures of grit exiting the nozzle of the torch of FIG. 7A. DETAILED DESCRIPTION

[0038] Referring to FIGs. 1A-1C, shown is one of the present systems 10 for testing the response of a substrate 22 to thermal runaway of a battery (e.g., of an electric vehicle). System 10 can comprise a torch 14 that can be configured to generate a flame and direct grit out of the torch. Furthermore, system 10 can comprise a frame 18 that can be configured to hold substrate 22 and can be positioned relative to torch 14 such that the substrate, when held in the frame, can be exposed to the flame and impinged by the grit to simulate the conditions that the substrate would be exposed to during thermal runway of a battery encased by the substrate.

[0039] As shown, torch 14 can comprise multiple containers — each comprising, for example, a tank (e.g., configured to hold gas and/or liquid) or a silo — that can hold flamegenerating materials and grit: an oxygen-containing gas supply 26, a fuel supply 30, and a grit supply 34.

[0040] Oxy gen-containing gas supply 26 and fuel supply 30 can contain gas and fuel, respectively, that can be readily ignited when mixed to generate a flame having an adequate temperature for the thermal-runaway simulation. The gas that can be held in oxygencontaining gas supply 26 can comprise, for example, air or concentrated oxygen, e.g., greater than or equal to any one of, or between any two of, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 99% (up to and including 100%) of the gas, by volume, can comprise oxygen. And fuel that fuel supply 30 can hold can comprise, for example, methane, propane, and/or liquefied petroleum gas (LPG).

[0041] Torch 14 can be configured such that gas from oxy gen-containing gas supply 26 and fuel from fuel supply 30 can be mixed prior to ignition thereof. To do so, torch 14 can comprise a burner assembly 36 that is in fluid communication with both oxygen-containing gas supply 26 and fuel supply 30 such that mixing occurs in the burner assembly. For example, as shown, torch 14 can comprise at least one gas line 46 and at least one fuel line 50, where gas is permitted to flow from oxy gen-containing gas supply 26 to a first gas inlet 58a of burner assembly 36 through one or more of the gas line(s) and fuel is permitted to flow from fuel supply 30 to a fuel inlet 62 of the burner assembly through one or more of the fuel line(s). Burner assembly 36 can comprise a first conduit 70a in fluid communication with both first gas inlet 58a and fuel inlet 62 such that the gas and fuel can enter and mix in the first conduit, which can be configured to direct the gas and the fuel to a nozzle 38 of torch 14 such that the gas and fuel flow through one or more openings 40 of the nozzle at the nozzle’s exit 44 and exit the torch. Torch 14 can comprise an ignitor 90 — which can be configured to, for example, generate a spark, heat one or more heating elements, generate a pilot flame, and/or the like for ignition — disposed downstream of the torch’s exit 42 to ignite the mixture and generate a flame.

[0042] At least through such pre-mixing, torch 14 can provide a more uniform flame and/or a higher flame velocity, such as when compared to a surface-mixed torch, which may better represent the conditions created by battery thermal runaway. To illustrate, a flame velocity provided by torch 14 can be greater than or equal to any one of, or between any two of: 45, 50, 55, 60, 65, 70, 75, 80, 85, and 90 m/s (FIG. 7B).

[0043] Grit supply 34 can hold grit that can simulate the material that would impinge on substrate 22 during thermal runaway of a battery. The grit that grit supply 34 can hold can be grit number 30, 36, 40, 46, 54, 60, or 70 — preferably grit number 46 or similar — under the American National Standards Institute (ANSI) standard B74. 12-2001, Table 3. For examples, ones of particles of the grit having a size that is less than or equal to any one of, or between any two of, 750, 600, 580, 560, 540, 520, 500, 480, or 460 micrometers (pm) can account for at least 90% of the particles of the grit, and an average size of the particles of the grit can be less than or equal to any one of, or between any two of, 450, 425, 400, 375, 350, 325, or 300 pm (e.g., less than or equal to 350 pm, such as about 330 pm). As used herein, a size of a particle can be the equivalent diameter of the particle if modelled as a sphere. The grit preferably comprises metal oxide particles such as aluminum oxide (AI2O3) particles.

[0044] Torch 14 can be configured such that the grit from grit supply 34 can be emitted out of burner assembly 36 with the gas and fuel from oxygen-containing gas supply 26 and fuel supply 30, which can allow the grit to be heated by the flame generated from the gas and fuel to more accurately simulate the conditions of thermal runaway of the battery. To do so, grit supply 26 can be in fluid communication with burner assembly 36, such as via at least one grit supply line 54 through which grit can flow from the grit supply to a grit inlet 66 of the burner assembly. Burner assembly 36 can comprise a second conduit 70b in fluid communication with grit inlet 66 such that the second conduit can receive the grit from grit supply 26. Second conduit 70b can be configured to direct the grit out of nozzle 38 such that the grit can flow out of torch 14 with the gas and fuel that, when ignited, can heat the grit.

[0045] Whether the ignition source (e.g., ignitor 90) is disposed downstream or upstream of torch exit 42, the ignition source can be positioned downstream of an exit 72 of second conduit 70b. Moreover, torch 14’s nozzle 38 may lack a convergent-divergent section; to illustrate (e.g., up until opening(s) 40), the nozzle can have a substantially constant cross- sectional area. In one or more of these ways, grit provided by second conduit 70b may not be overheated (e.g., melted) and/or over sped by torch 14, allowing the torch to provide grit to a substrate at a temperature and velocity that better reflect conditions of battery thermal runaway. For example, grit provided by torch 14 to a substrate may be at a temperature that is less than the melting point of the grit and/or can be provided to the substrate a velocity that is less than 100 m/s, such as less than or equal to any one of, or between any two of: 100, 90, 80, 70, 60, 50, and 40 m/s. To facilitate the flow of grit from grit supply 34 to burner assembly 36 and thus to second conduit 70b, the grit supply can be disposed higher than the burner assembly (and thus its second conduit) such that grit can fall through grit supply line(s) 54 under the force of gravity. Furthermore, torch 14 can comprise one or more mechanisms to stir, agitate, and/or fluidize grit in grit supply 34 to encourage the grit to flow to burner assembly 36 and its second conduit 70b. In the embodiment shown, torch 14 can be configured to permit gas to be injected into grit supply 34 to fluidize the grit, which can be gas from a second gas supply 28 (e.g., a tank configured to hold gas) that contains, for example, compressed air. For example, torch 14 can comprise multiple gas lines 46, and gas can be permitted to flow from second gas supply 28 to grit supply 34 through one or more of the gas lines, thereby promoting grit flow through grit supply line 54. Employing a second gas supply 28 for grit fluidization that is independent of oxygen-containing gas supply 26 can beneficially allow different gases to be used for fluidization and flame generation; while concentrated oxygen (e.g., gas in which at least 30%, up to and including 100%, of the gas, by volume, can comprise oxygen) may be well-suited as an oxidizing gas for flame generation, it can pose fire risks if used for grit fluidization. Thus, oxygen-containing gas supply 26 can contain concentrated oxygen for flame generation while second gas supply 28 can contain an inert gas like compressed air. In other embodiments, however, system 10 need not include a second gas supply 28, and oxy gen-containing gas supply 26 can supply gas to grit supply 34 for grit fluidization, e.g., gas can be permitted to flow from the oxy gen-containing gas supply to the grit supply through one or more of gas lines 46 disposed upstream of burner assembly 36 (e.g., without flowing through the burner assembly) such that the gas can enter the grit supply and fluidize grit disposed therein.

[0046] To facilitate the flow of grit through second conduit 70b and out of nozzle 38, torch 14 can be configured to direct gas to the second conduit, which can entrain the grit that burner assembly 36 receives from grit supply 34 to propel the grit through the second conduit and out of the nozzle. As shown, the gas that torch 14 can direct to second conduit 70b can be from second gas supply 28. For example, torch 14 can comprise multiple gas lines 46 and can be configured such that gas can flow from second gas supply 28 to a second gas inlet 58b of burner assembly 26 through one or more of the gas lines. In other embodiments, however, the gas that torch 14 can direct to second conduit 70b can be from oxy gen-containing gas supply 26, e.g., such that gas can flow from the oxy gen-containing gas supply to second gas inlet 58b through one or more of gas lines 46. Second gas inlet 58b can be in fluid communication with grit inlet 66 and second conduit 70b such that the gas — whether from second gas supply 28 or oxy gencontaining gas supply 26 — can entrain the grit and propel it through the second conduit.

[0047] Torch 14 can comprise one or more mechanisms to control the flow of gas, fuel, and grit from oxygen-containing gas supply 26, fuel supply 30, grit supply 34, and optional second gas supply 28. Such control can be desirable to control the temperature of the flame generated by torch 14 and the rate at which grit impinges on substrate 22 in accordance with target simulation conditions. For example, the ratio of gas and fuel flowing through first conduit 70a and the flow rate of the mixture through torch 14’ s exit 42 can affect the temperature of the flame generated from the ignition of the mixture. And the rate at which gas enters second conduit 70b (and, optionally, grit supply 34 for fluidization) can affect the rate at which grit is directed through the second conduit and out of torch 14 for impingement on substrate 22.

[0048] As shown, such control can be effected with two or more (e.g., three or more) pressure regulators 74 and/or a plurality of valves 78 (e.g., gate valves, ball valves, and/or the like). For example, pressure regulators 74 can be disposed upstream of burner assembly 36 (and thus of its first and second conduits 70a and 70b), with at least one of the pressure regulators in fluid communication with oxygen-containing gas supply 26 and at least another one of the pressure regulators in fluid communication with fuel supply 30 to control the pressure of gas and fuel flowing to the burner assembly (and of gas flowing to grit supply 34 for grit fluidification if the oxygen-containing gas supply is used for that purpose). If system 10 includes a second gas supply 28, at least one of pressure regulators 74 can be in fluid communication with the second gas supply to control the pressure of gas flowing to burner assembly 36 and/or to grit supply 34 from the second gas supply. Furthermore, one or more of valves 78 can be configured control the rate at which gas flows from oxy gen-containing gas supply 26 to first conduit 70a, one or more of the valves can be configured to control the rate at which fuel flows from fuel supply 30 to the first conduit, and one or more of the valves can be configured to control the rate at which grit flows from the grit supply to second conduit 70b. For grit fluidization, at least one of valves 78 can be configured to control the rate at which gas flows to grit supply 34, whether from optional second gas supply 28 (e.g., as shown) or from oxy gen-containing gas supply 26. And for grit entrainment, at least one of valves 78 can be configured to control the rate at which gas flows to second conduit 70b, whether from optional second gas supply 28 (e.g., as shown), or from oxygen-containing gas supply 26.

[0049] To facilitate appropriate pressure regulation and/or valve control, torch 14 can further comprise a plurality of flow sensors 82 and/or one or more temperature sensors 94. At least one of flow sensors 82 can be configured to measure a rate at which gas from oxygencontaining gas supply 26 flows toward first conduit 70a, at least one of the flows sensors can be configured to measure the rate at which fuel from fuel supply 30 flows toward the first conduit, at least one of the flow sensors can be configured to measure the rate at which gas (whether from second gas supply 28 or the oxygen-containing gas supply) flows toward grit supply 34, and/or at least one of the flow sensors can be configured to measure the rate at which gas flows toward second conduit 70b (whether from the second gas supply or the oxy gencontaining gas supply). Flow sensors 82 can thus provide flow rate information usable to control pressure regulators 74 and/or valves 78 (e.g., manually or, if system 10 includes a controller, automatically) and thus the flow rates of gas, fuel, and grit that can affect the temperature of the flame generated by torch 14 and the rate at which grit impinges substrate 22. One or more temperature sensors 94, which can comprise, for example, a thermocouple and/or an infrared camera, can be configured to measure a temperature of the flame generated by the torch. For example, a thermocouple can be disposed downstream of torch 14’s exit 42 to measure the flame temperature. Based on the target flame temperature, such information can be used to control the flow rates of gas and fuel to first conduit 70a and thus the temperature of the flame generated from the ignition of the gas-fuel mixture. Furthermore, at least one temperature sensor (e.g., a thermocouple) can be disposed downstream of substrate 22 to measure and record a temperature of a downstream surface of the substrate that is not exposed to the flame.

[0050] Torch 14 can also comprise at least two check valves 86. One of check valves 86 can be disposed between oxy gen-containing gas supply 26 and first and/or second conduits 70a and 70b such that fluid cannot flow from the first conduit or from the second conduit to the oxygen-containing gas supply through the check valve. Furthermore, one of check valves 86 can be disposed between fuel supply 30 and first conduit 70a such that fluid cannot flow from the first conduit to the fuel supply through the check valve. If system 10 includes a second gas supply 28, one of check valves 86 can be disposed between the second gas supply and the second conduit such that fluid cannot flow from the second conduit to the second gas supply through the check valve.

[0051] The arrangement and relative sizes of nozzle 38 and second conduit 70b can facilitate the heating of grit exiting torch 14 and thus the accuracy of the thermal runaway simulation. First, as shown in FIG. 1C, exit 42 of torch 14 through which gas from oxy gencontaining gas supply 26 and fuel from fuel supply 30 are permitted to exit the torch can be defined by opening(s) 40 of nozzle 38 and second conduit 70b (e.g., exit 72 of the second conduit can coincide with or extend downstream of the nozzle’s exit 42), or — as shown in FIG. 2 — the second conduit’s exit can be disposed upstream of the exit of the torch through which the gas and fuel are emitted such that the nozzle’s opening(s) alone define that exit. Preferably, second conduit 70b’s exit 72 is disposed upstream of or at nozzle 38’s exit 44 (e.g., with a distance between the second conduit’s exit and the nozzle’s exit being less than or equal to any one of, or between any two of, 20, 18, 16, 14, 12, 10, 8, or 6 millimeters (mm)) to facilitate the combination of grit leaving the second conduit with the gas-fuel mixture emitted from torch 14’s exit 42 prior to ignition thereof. If second conduit 70b’s exit 72 extends past nozzle 38’s exit 44, the extension is preferably relatively minimal such that the second conduit’s exit remains upstream of ignitor 90 for pre-ignition combination of the grit and gasfuel mixture; for example, a distance between the second conduit’s exit and the nozzle’s exit can be less than or equal to any one of, or between any two of, 30, 26, 22, 18, 14, 10, 6, or 2 mm. A temperature of the flame generated from the ignition of the gas-fuel mixture may be higher near the ignition point such that the combination of the grit with the gas-fuel mixture prior to ignition can allow the grit to be exposed to the higher flame temperature to facilitate heating.

[0052] Furthermore, opening(s) 40 of nozzle 38 can comprise no more than 5 openings such that the flame that the torch generates is concentrated about the grit. As shown, nozzle 38 includes a single opening 40 at its exit 44. When both opening 40 and second conduit 70b define exit 42 of torch 14 (FIG. 1C), the torch’s exit can comprise a portion of the opening that is disposed between second conduit 70b and an interior surface 48 of the nozzle that circumscribes the opening. However, when second conduit 70b’s exit 72 is disposed upstream of exit 42 of torch 14 (FIG. 2), the torch’s exit can comprise opening 40 itself.

[0053] Nevertheless, and referring to FIG. 3, a nozzle 38’s opening(s) 40 can comprise any suitable number of openings, such as greater than or equal to any one of, or between any two of: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 openings (e.g., 52 openings, as shown). To illustrate, the openings can be disposed in concentric rings, and, in each of the rings, the openings of the ring can be disposed relative to one another at equiangular intervals about the center of the nozzle. Each of the rings can be disposed at a same radial distance from each adjacent one of the rings (e.g., .25 inches, as shown). Further, openings 40 of FIG. 3’s nozzle can have substantially the same cross-sectional area (e.g., diameter). In one or more of these ways, the openings 40 can facilitate flame stabilization by, for example, encouraging laminar flow of fuel and gas out of nozzle 38.

[0054] In FIG. 3’s nozzle 38, a portion of the nozzle upstream of openings 40 can be in fluid communication with each of the openings. To illustrate, openings 40 can be defined by a plate at exit 44 of the nozzle.

[0055] Referring additionally to FIG. 4, whether both nozzle 38’s opening(s) 40 and second conduit 70b or the nozzle’s opening(s) alone define torch 14’s exit 42, exit 72 of second conduit 70b can be sized to promote an appropriate velocity of grit exiting the second conduit. For example, as shown, second conduit 70b can have a first maximum interior transverse dimension 98a (e.g., an interior diameter, if the second conduit has a circular cross-section) at the second conduit’s exit 72 that can be, for example, less than or equal to any one of, or between any two of, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, or 2 mm (e.g., less than or equal to 8 mm, such as less than or equal to 4.5 mm), and can likewise have a first interior cross-sectional area at the second conduit’s exit that is less than or equal to any one of, or between any two of, 100, 90, 80, 70, 60, 50, 40, 35, 30, 25, 20, 15, or 10 mm² (e.g., less than or equal to 35 mm², such as less than or equal to 15 mm²), which can promote grit velocities that accurately simulate a thermal runaway scenario.

[0056] To facilitate an adequate flow of the gas-fuel mixture for the generation of a gritheating flame, opening(s) 40 of nozzle 38 can have a second interior cross-sectional area (e.g., the collective cross-sectional area of the opening(s)) that is greater than the first interior cross- sectional area of second conduit 70b’s exit 72. However, opening(s) 40 can remain relatively close to second conduit 70b’s exit 72 and their second interior cross-sectional area need not significantly exceed the first interior cross-sectional area such that the flame generated by torch 14 is concentrated about the grit that the second conduit directs out of nozzle 38. For example, for each of opening(s) 40, there can be a transverse distance 100 between second conduit 70b’s centerline 76 at the second conduit’s exit 72 and an interior surface 48 of the nozzle that circumscribes the opening; the transverse distance can be a component, measured in a direction that is parallel to first maximum interior transverse dimension 98a, of a total distance between the centerline and the circumscribing interior surface. For each of opening(s) 40, transverse distance 100 can be greater than half first maximum interior transverse dimension 98a but still less than or equal to any one of, or between any two of, 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.9, 0.8, 0.7, 0.6, or 0.5 times the first maximum interior transverse dimension, such as less than or equal to any one of, or between any two of, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, or 4 mm (e.g., less than or equal to 8 mm). The second interior cross-sectional area of opening(s) 40 can likewise be less than or equal to any one of, or between any two of, 40.0, 30.0, 20.0, 18.0, 16.0, 14.0, 12.0, 10.0, 5.0, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, or 1.5 times (e.g., less than or equal to 30 times, such as from 2 times to 30 times) the first interior cross-sectional area of second conduit 70b, such as less than or equal to any one of, or between any two of, 2200, 2000, 1800, 1600, 1400, 1200, 1000, 800, 600, 500, 400, 300, 200, 175, 150, or 125 mm² (e.g., less than or equal to 150 mm²). Such a transverse distance 100 (relative to first maximum interior transverse dimension 98a) and/or second maximum interior cross-sectional area (relative to the first maximum interior cross-sectional area) can be critical for the gas-fuel mixture — and thus the flame generated therefrom — to remain relatively close to the grit and thereby promote heating of the grit for an accurate simulation of thermal runaway of a battery. [0057] Exit 42 of torch 14 can have a third interior cross-sectional area that can be the same as the second interior cross-sectional area of opening(s) 40 when the opening(s) define the exit (FIG. 2). If opening(s) 40 and second conduit 70b together define exit 42 of torch 14 (FIG. 1C), the third interior cross-sectional area can still be greater than the first cross-sectional area as well — albeit smaller than the second interior cross-sectional area — to promote adequate flow of the gas-fuel mixture. But, as with the second interior cross-sectional area, the third interior cross-sectional area need not be significantly greater than the first interior cross-sectional area such that flame concentration can be maintained about the grit. For example, the third interior cross-sectional area can be less than or equal to any one of, or between any two of, 40.0, 30.0, 20.0, 18.0, 16.0, 14.0, 12.0, 10.0, 5.0, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, or 1.5 times (e.g., less than or equal to 30 times, such as from 2 times to 30 times) the first interior cross-sectional area, such as less than or equal to any one of, or between any two of, 2200, 2000, 1800, 1600, 1400, 1200, 1000, 800, 600, 500, 400, 300, 200, 175, 150, 125, 100, or 75 mm² (e.g., less than or equal to 150 mm² or less than or equal to 125 mm²).

[0058] As shown, first conduit 70a that directs gas from oxy gen-containing gas supply 26 and fuel from fuel supply 30 to nozzle 38 can surround second conduit 70b to define a volume 106 between the first and second conduits. Volume 106 can have a fourth interior cross- sectional area that is larger than the first, second, and third interior cross-sectional areas of second conduit 70b’s exit 72, nozzle 38’s opening(s) 40, and torch 14’s exit 42, respectively, to further promote the flow of the gas-fuel mixture, within appropriate limits to facilitate flow into the smaller flow area of the nozzle. For example, the fourth interior cross-sectional area can be less than or equal to any one of, or between any two of, 40, 35, 30, 25, 20 15, 14, 13, 12, 11, 10, 9, 8, 7, or 6 times (e.g., from 10 to 40 times) the first interior cross-sectional area of second conduit 70b’s exit 72.

[0059] Furthermore, to generate turbulent flow in second conduit 70b that can facilitate the combination of grit with the gas-fuel mixture, the second conduit can comprise a linear portion 102 (which can make up the entirety of the second conduit) having a second maximum interior transverse dimension 98b (e.g., an interior diameter, if the linear portion of the second conduit has a circular cross-section) that is relatively small relative to length 108 of the linear portion (FIGs. 1C, 2, and 3). For example, length 108 of linear portion 102 can be greater than or equal to any one of, or between any two of, 20, 30, 40, 50, 60, 70, 80, 90, or 100 times (e.g., greater than or equal to 50 times) second maximum interior transverse dimension 98b, such as greater than or equal to any one of, or between any two of, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 600, 700, or 800 mm (e.g., greater than or equal to 275 mm). Second maximum interior transverse dimension 98b in linear portion 102 is optionally the same as first maximum interior transverse dimension 98a at second conduit 70b’s exit 72, such as less than or equal to any one of, or between any two of, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, or 2 mm (e.g., less than or equal to 8 mm, such as less than or equal to 4.5 mm), which can facilitate the acceleration of grit in the second conduit.

[0060] Referring again to FIGs. 1A and IB, system 10’s frame 18 can be configured to position substrate 22 in front of and in fixed relation relative to nozzle 38 such that the substrate can be exposed to the flame that torch 14 generates and impinged by the grit directed out of the nozzle. To illustrate, a portion of frame 18 configured to hold substrate 22 can define two channels 122, each configured to receive a respective one of opposing sides of the substrate, and can comprise, for each of the channels, at least one fastener 126 that, when tightened, can impinge on and thus hold the side of the substrate in the channel.

[0061] Frame 18 can position substrate 22 such that a distance 110 between nozzle 38 and the substrate is sufficient to allow heating of the grit but short enough to permit grit to impinge on the substrate with an adequate velocity for the thermal runaway simulation. For example, frame 18 can position substrate 22 such that distance 110 is greater than or equal to any one of, or between any two of, 1.25, 1.5, 1.75, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 20.0, 30.0, 40.0, or 50.0 cm (e.g., between 1.25 and 13.0 cm). Furthermore, while in some embodiments frame 18 can hold substrate 22 at only one position relative to nozzle 38, in other embodiments the frame can hold the substrate at different positions relative to the nozzle (e.g., to simulate different conditions); for example, a portion of the frame that is configured to hold the substrate can, when unsecured, be movable relative to the nozzle and can be secured at a desired position to hold the substrate in fixed relation relative to the nozzle. [0062] Referring to FIGs. 4A and 4B, illustrated are some of the present methods for testing the response of a substrate (e.g., 22) to thermal runaway of a battery, which can be performed using any of the above-described systems (e.g., 10). The substrate tested can comprise a sheet of material — which can have opposing planar surfaces — being investigated for use to encase a battery (e.g., a battery of an electric vehicle), such as a sheet of a material comprising a polymer and/or a metal. For example, the sheet of material can comprise a polymer like polypropylene and, optionally, a plurality of nonwoven, woven, and/or unidirectional fibers (e.g., glass fibers, carbon fibers, and/or the like) dispersed in the polymer. The system’s frame (e.g., 18) can hold the substrate such that the substrate is in front of and in fixed relation relative to the system’s nozzle (e.g., 38).

[0063] Some methods comprise a step of exposing the substrate to a flame (e.g., 114) generated by the torch (e.g., 14) (FIG. 5A). As described above, the flame can be generated from gas from the oxy gen-containing gas supply (e.g., 26) and fuel from the fuel supply (e.g., 30) that are directed by the first conduit (e.g., 70a) to the nozzle such that the gas and fuel flow through the opening(s) (e.g., 40) of the nozzle and out of an exit (e.g., 42) of the torch; the gas and fuel can be ignited using, for example, an ignitor (e.g., 90) disposed downstream of the torch’s exit. The flame can have a temperature and a heat power that appropriately simulate thermal runaway conditions, which can depend on the type of battery being simulated. For example, a maximum temperature of the flame can be greater than or equal to any one of, or between any two of, 500, 600, 700, 800, 900, 1,000, 1,100, 1,200, 1,300, 1,400, 1,500, 1,600, 1,700, 1,800, 1,900, or 2,000 °C (e.g., between 1,000 and 2,000 °C or between 1,500 and 2,000 °C), and a heat power of the flame can be greater than or equal to any one of, or between any two of, 500, 1,000, 2,000, 3,000, 4,000, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 11,000, or 12,000 Watts (W) to simulate athermal runaway scenario.

[0064] The flow of gas from the oxy gen-containing gas supply and fuel from the fuel supply can be controlled as described above to achieve a gas-fuel ratio and a mixture flow rate required to achieve a target temperature and heat power. For example, if the gas from the oxygencontaining gas supply is air (e.g., with less than or equal to 30% of the gas, by volume, comprising oxygen), relatively more air than fuel can be directed through the first conduit and out of the nozzle’s exit, e.g., with a flow rate of the air through the first conduit being at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or 20 times a flow rate of fuel through the first conduit. To illustrate, a flow rate of air through the first conduit can be greater than or equal to any one of, or between any two of, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, or 200 standard cubic feet per hour (SCFH) and a flow rate of fuel, such as propane, through the first conduit can be greater than or equal to any one of or between any two of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, or 50 SCFH. However, different flow rates can be used depending on the gas and fuel used (e.g., a lower gas flow rate may be used with gases having a higher concentration of oxygen and a lower fuel flow rate may be used with fuels having a higher energy density).

[0065] Some methods also comprise a step of impinging the substrate with grit (e.g., 118) from the grit supply (e.g., 34) (FIG. 5A), which as noted above can be achieved by directing the grit out of the nozzle with the second conduit (e.g., 70b), such as by directing gas (e.g., from a second gas supply (e.g., 28) or the oxygen-containing gas supply) through the second conduit to entrain the grit. The flow of grit and gas to the second conduit (and of gas to the grit supply for fluidization, if employed) can be controlled as described above to achieve a grit flow rate and velocity that are representative of what occurs in a particular thermal runaway scenario (which can depend on, for example, the type of battery being simulated). For example, a rate at which the grit flows through the second conduit can be greater than or equal to any one of, or between any two of, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0 grams per second (g/s) (e.g., greater than or equal to 1.75 g/s, such as between 1.75 and 2.25 g/s), and a velocity of the grit at the exit (e.g., 72) of the second conduit can be greater than or equal to any one of, or between any two of, 20, 40, 60, 80, 100, 120, 140, 160, 180, 200 meters per second (m/s) (e.g., greater than or equal to 26 m/s, such as between 26 and 38 m/s). Any suitable flow rate of gas through second conduit can be employed to achieve such flow rates and velocities of grit; to illustrate, a flow rate of gas through the second conduit can be relatively large, such as greater than or equal to any one of, or between any two of, 10, 100, 200, 300, 400, or 500 SCFH (e.g., greater than or equal to 40 SCFH or greater than or equal to 80 SCFH). [0066] As described above, the flow of the gas-fuel mixture out of the nozzle can remain relatively close to the grit and the grit can accordingly be disposed in the flame generated from the gas-fuel mixture such that the flame heats the grit. With the flame concentrated about the grit, there can be a relatively high heat flux on the portion of the substrate exposed to the flame and impinged by the grit, such as a heat flux that is greater than or equal to any one of, or between any two of, 25, 50, 100, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 500, 600, 700, 800, 900, 1000 kW/m² The grit can thus have a relatively high temperature upon impingement of the substrate, such as a temperature that is greater than or equal to any one of, or between any two of, 200, 300, 400, 500, 600, 700, 800, 900, or 1,000 °C (e.g., greater than 750 °C). Such high-temperature grit impinging on the substrate can more accurately simulate the thermal runaway scenario.

[0067] A distance (e.g., 110) between the nozzle and the substrate can be long enough to allow adequate heating of the grit and short enough to allow the grit to maintain adequate velocity for impingement on the substrate. For example, the distance between the nozzle and the substrate can be greater than or equal to any one of, or between any two of, 1.25, 1.5, 1.75, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 20.0, 30.0, 40.0, or 50.0 cm (e.g., between 1.25 and 13.0 cm).

[0068] Once begun, the impinging can be performed continuously until bum-through of the substrate (e.g., until a hole is formed through the portion of the substrate exposed to the flame and impinged on by the grit) (FIG. 5B), although in other embodiments the impinging can be performed intermittently. In particular, the impinging can be can be performed during intervals lasting, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more seconds, and such intervals can be separated by, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more seconds. During the time between impingement intervals, the substrate can continue to be exposed to the flame. Such a cyclic mode of grit impingement can be used to differentiate substrate materials from one another based on, for example, how many cycles of grit impingement the substrates withstand before failure (e.g., bum-through).

[0069] With the substrate being exposed to a flame concentrated about the grit that impinges on the substrate, the amount of time for bum-through to occur may more accurately reflect the bum-through time in a thermal runaway scenario, compared to conventional tests that employ a flame alone or grit that is not subject to the same level of heating. EXAMPLES

[0070] The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters that can be changed or modified to yield essentially the same results.

Example 1

[0071] Referring to FIGs. 5 A and 5B, the response of a substrate to thermal runaway of a battery was tested using the system of FIGs. 1A-1C. The substrate tested was a sheet of PPcompound Hl 030 from SABIC® that had a thickness of 4 mm.

[0072] In a first test, the substrate was only exposed to a flame generated by the torch, and in a second test the substrate was exposed to a flame generated by the torch and impinged by grit directed out of the nozzle of the torch. In both tests, the flame was generated by directing propane and compressed air through the first conduit and out of the exit of the torch for ignition. The flow rate of the propane was 15 SCFH and the flow rate of the air was 50 SCFH. In both tests, a temperature of the resulting flame exceeded 1,000 °C, a heat power of the flame was about 12 kW, and a heat flux at the portion of the substrate exposed to the flame was between 300 and 500 kW/m²

[0073] In the second test in which the substrate was impinged by grit, the grit was grit number 46, with particles having an average size of 330 pm. The grit was directed out of the nozzle at a rate of 2 g/s. To propel the grit out of the nozzle, air was directed through the second conduit at a flow rate of 100 SCFH to entrain and accelerate the grit for impingement on the substrate.

[0074] In the first test with no grit impingement, bum-through of the substrate occurred in about 5 minutes, while in the second test with both flame exposure and grit impingement bum- through of the substrate occurred in about 1.5 minutes. The tests illustrated how the combination of the flame and grit can cause significantly faster bum-through, which may more accurately simulate what might occur during thermal runaway of a battery.

Example 2

[0075] A computational fluid dynamics simulation was performed to simulate flame and grit temperatures, gas velocities, and grit velocities that can be achieved when generating a flame and emitting Number 46 grit from one of the present torches. In the simulated torch, the first conduit had an internal diameter of 0.75 inches (19.05 mm), the second conduit had an internal diameter of 0.152 inches (3.86 mm), and the nozzle had an internal diameter of 0.50 inches (12.7 mm). FIG. 7A illustrates the simulated flame temperatures in Celsius, FIG. 7B illustrates simulated velocities of gas exiting the nozzle from the second conduit in meters per second, FIG. 7C illustrates simulated velocities of grit exiting the nozzle from the second conduit in meters per second, and FIG. 7D illustrates simulated temperatures of grit exiting the nozzle from the second conduit in Celsius.

[0076] The above specification and examples provide a complete description of the structure and use of illustrative embodiments. Although certain embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this invention. As such, the various illustrative embodiments of the products, systems, and methods are not intended to be limited to the particular forms disclosed. Rather, they include all modifications and alternatives falling within the scope of the claims, and embodiments other than the one shown may include some or all of the features of the depicted embodiment. For example, elements may be omitted or combined as a unitary structure, and/or connections may be substituted. Further, where appropriate, aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples having comparable or different properties and/or functions, and addressing the same or different problems. Similarly, it will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments.

[0077] The claims are not intended to include, and should not be interpreted to include, means-plus- or step-plus-function limitations, unless such a limitation is explicitly recited in a given claim using the phrase(s) “means for” or “step for,” respectively.

Claims

1. A system for testing the response of a substrate to thermal runaway of a battery, the system comprising: a torch having: an oxy gen-containing gas supply, a fuel supply, and a grit supply; a nozzle defining one or more openings at an exit of the nozzle; a first conduit configured to direct gas from the oxy gen-containing gas supply and fuel from the fuel supply to the nozzle such that the gas and fuel flow through each of the opening(s) of the nozzle; and a second conduit configured to direct grit from the grit supply out of the nozzle, the second conduit having a first maximum interior transverse dimension at an exit of the second conduit through which grit from the grit supply is permitted to exit the second conduit; and wherein the opening(s) of the nozzle or the opening(s) of the nozzle and the second conduit define an exit of the torch through which gas from the oxygen-containing gas supply and fuel from the fuel supply are permitted to exit the torch; a frame configured to position a substrate in front of and in fixed relation relative to the nozzle; and an ignitor disposed downstream of the exit of the torch.

2. The system of claim 1, wherein: the second conduit has a first interior cross-sectional area at the exit of the second conduit; and the opening(s) of the nozzle have a second interior cross-sectional area that is: greater than the first interior cross-sectional area; and less than or equal to 30 times the first interior cross-sectional area.

3. The system of claim 1 or 2, wherein: the second conduit has a first interior cross-sectional area at the exit of the second conduit; and the exit of the torch has a third interior cross-sectional area that is from 2 times to 30 times the first interior cross-sectional area.

4. The system of any of claims 1-3, wherein the one or more openings of the nozzle comprise no more than 5 openings.

5. The system of any of claims 1-4, wherein the second conduit includes a linear portion having a second maximum interior transverse dimension and a length that is at least 50 times the second maximum interior transverse dimension.

6. The system of any of claims 1-5, wherein: the second conduit has a first interior cross-sectional area at the exit of the second conduit; the first conduit surrounds the second conduit to define a volume between the first conduit and the second conduit; and the volume has a fourth interior cross-sectional area that is from 20 to 40 times the first interior cross-sectional area.

7. The system of any of claims 1-6, wherein the torch comprises a second gas supply that is in fluid communication with: the second conduit such that gas is permitted to flow from the second gas supply to the second conduit, the second conduit configured to direct the gas from the second gas supply out of the nozzle with the grit from the grit supply; and the grit supply such that gas is permitted to flow from the second gas supply to the grit supply.

8. The system of any of claims 1-7, wherein the exit of the second conduit is disposed upstream of the exit of the torch.

9. The system of any of claims 1-8, wherein for each of the opening(s) of the nozzle, a transverse distance between a centerline of the second conduit at the exit of the second conduit and an interior surface of the nozzle circumscribing the opening is: greater than half of the first maximum interior transverse dimension; and less than or equal to 2 times the first maximum interior transverse dimension.

10. A method for testing the response of a substrate to thermal runaway of a battery using the system of any of claims 1-9, the method comprising: exposing the substrate to a flame generated by the torch; and impinging the substrate with grit from the grit supply.

11. The method of claim 10, wherein the grit is at a temperature that is greater than 200 °C upon impingement of the substrate.

12. The method of claim 10 or 11, wherein a maximum temperature of the flame is between 1,000 and 2,000 °C.

13. The method of any of claims 10-12, wherein a distance between the nozzle and the substrate is between 1.25 and 50.0 centimeters.

14. The method of any of claims 10-13, wherein, once begun, the impinging is performed continuously until bum-through of the substrate.

15. The method of any of claims 10-14, wherein the substrate comprises a sheet of material, the sheet of material comprising a polymer.