CN116569438A - Thermal runaway detection system for battery within enclosure and method of using same - Google Patents

Abstract

A battery thermal runaway detection sensor system for use within a battery enclosure housing one or more batteries. The system has at least one gas sensor for detecting an exhaust condition of the battery cell and providing a sensed output in real time. A microcontroller determines power management and signal conditioning outputs for a particular battery exhaust gas concentration based on the sensed outputs from the at least one gas sensor. Methods of using such sensor systems are also described.

Description

Thermal runaway detection system for battery within enclosure and method of using same

Cross Reference to Related Applications

The present application is a continuation-in-part application from U.S. application Ser. No. 17/021,711, filed on even 15, 9, 2020, and claims the benefit of U.S. provisional application Ser. No. 63/202,962, filed on even 1,7, 2021, each of which is hereby incorporated by reference in its entirety.

Technical Field

The present disclosure relates generally to a detection system for detecting battery failure, and more particularly to a detection system for detecting thermal runaway of a battery within a housing, such as a battery for use with an electric vehicle, fig. 2 (a), or a stationary battery energy storage system, fig. 2 (b). The present disclosure also relates to methods of detecting thermal runaway in a battery using such systems.

Background

As lithium ion battery technology improves, the battery energy density continues to increase, and this in turn increases the risk of battery failure. Thermal runaway of lithium ion batteries is an important safety issue for electric vehicles. For example, global technical specifications No. 20 regarding Electric Vehicle Safety (EVS) proposed by United Nations (United states) require that a warning be issued 5 minutes in advance before evolving into a dangerous situation caused by thermal runaway.

Referring to fig. 1 (a), 1 (b), thermal runaway of a lithium ion-based battery is a process in which an exothermic reaction occurs within a failed battery cell, such that the internal temperature increases, which in turn releases energy to sustain internal degradation reactions and increases the temperature until the battery cell eventually fails, which is typically accompanied by abrupt release of electrolyte and decomposed gas products, possibly leading to a fire. In modern lithium batteries the risk of explosion can be reduced by incorporating a controlled venting site design in the battery cell (see fig. 4), but in most liquid electrolyte lithium based batteries the risk of fire and explosion due to thermal runaway is not eliminated.

Returning to fig. 1 (a), 1 (b), certain triggers and abuse conditions may lead to breakdown or failure of the battery, e.g., a lithium ion battery cell, which in turn may cause thermal runaway. Thermal runaway may be caused by, for example, external shorts, internal shorts (particles, dendrites, individual failures, bumps/punctures), overcharging, overdischarging, external heating, or overheating (self-heating). Accompanying the temperature rise is the generation of gas. If the heat dissipation is faster than the heat generation, the result is safe.

However, if left unhindered, or if the heat cannot be dissipated faster than it is generated, this may lead to a rapid increase in temperature, release of flammable and dangerous gases during the exhaust, flame and possibly explosion. This is particularly problematic for vehicles with large battery systems, as shown in fig. 3, and particularly battery electric vehicles and stationary storage, in which case thermal runaway of the individual battery cells (fig. 4) may result in a series of thermal runaway events that may engulf the entire battery pack, resulting in catastrophic fire and release of harmful gases. Although the battery pack may be constructed to passively contain several failed battery cells and meet EVS specifications, thermal runaway propagation may still occur. Therefore, it is very important to detect that the battery cells inside the pack are experiencing thermal runaway.

Sensors have been developed for detecting thermal runaway. However, simple gas sensors, such as hydrocarbon sensors, can only detect electrolyte gas concentrations, but also have cross sensitivity to other gases and significant drift, and thus make long-lived thermal runaway detection sensors poor.

Thus, there is a need for a powerful, fast and reliable early detection system for detecting thermal runaway in mobile and stationary applications.

Citation of any reference herein is not an admission that it constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents and information.

Disclosure of Invention

A detection system is disclosed that addresses the challenges of rapid, robust thermal runaway detection within a battery enclosure that is generally unaffected by electrochemistry, cell packaging (cylindrical, prismatic, or pouch), cell size, and cell configuration (series/parallel) by identifying the nature of the initial cell venting common among numerous design types and responding to venting of the gas of a failed cell.

During the thermal runaway decomposition reaction, when the errant cell is in a high state of charge, fig. 1 (b), the cell converts a large amount of cathode and electrolyte material into gas and discharges the pressurized gas mixture over a time span of seconds. In typical cell chemistries such as lithium manganese cobalt oxide (NMC) cells, lithium Cobalt Oxide (LCO) and lithium iron phosphate (LFP) cells, thermal runaway tests show the release of several gases, including large amounts of carbon dioxide and hydrogen, see fig. 5. Carbon dioxide is typically evolved during the oxidation reaction of carbonate solvents, and hydrogen is typically released as a product of the water reduction derived from the combustion reaction of carbon monoxide and/or free lithium, where methane and ethane compounds are also present in the reduction reaction of electrolyte and ethylene carbonate at the lithiated anode.

The use of such systems is also disclosed for detecting (e.g., early detection of) thermal runaway, thereby helping to prevent cell-to-cell propagation of thermal runaway from a single cell, for example. In one embodiment, cell venting is detected. In one embodiment, thermal runaway is detected. In one embodiment, thermal runaway decomposition products are detected.

In other examples of the present disclosure, at least one additional sensor is provided for detecting a secondary condition of the battery and providing information in real time regarding the rate of progression of the battery cell venting and thermal runaway, the information comprising pressure or temperature, wherein the microcontroller provides the rate of progression of thermal runaway based on the provided information from the secondary sensor. The at least one additional sensor may detect pressure or temperature in the battery compartment housing to determine the rate of progression of the vent/the thermal runaway. A sensor housing may be provided for enclosing the at least one sensor and the at least one secondary sensor. The outputs from the primary and secondary gas sensors allow for distinguishing electrolyte leakage from exhaust/thermal runaway. System software may be embedded within the sensor microcontroller to determine if a threshold level of thermal runaway has been exceeded and send an alert to the battery management microcontroller or the charging system controller.

In still other example embodiments, the threshold level of thermal runaway is selected from the following: (i) carbon dioxide levels greater than about 10,000 ppm; (ii) hydrogen levels greater than about 40,000 ppm; (iii) carbon dioxide levels above its lower explosion limit; (iv) a hydrogen level above its lower explosion limit; and (v) any combination thereof. A multi-chip printed circuit board may be provided for mounting on a battery management controller printed circuit board. A power management system may be provided that enables a fast data acquisition mode during charging/discharging of an active battery system, and a reduced acquisition rate/lower power mode when the battery system is neither charging nor discharging. The detection system may send a wake-up command to the main battery system controller when an exhaust/thermal runaway is detected. The sensor system may comprise a plurality of gas sensors selected from more than one hydrogen sensor, more than one carbon monoxide sensor, more than one carbon dioxide sensor, and any combination of any of the foregoing to achieve redundancy in safety critical applications. The detection system may also include a humidity sensor, a pressure sensor, a temperature sensor, or any combination thereof.

In another example embodiment, a method for detecting a thermal runaway condition of a battery within a battery enclosure is provided. The method comprises providing a detection system as described above, measuring and/or analyzing one or more gases emitted from the battery, and determining whether the analyzed gas level is at or above a predetermined threshold level indicative of thermal runaway of the battery. The analyzed gas may comprise hydrogen, carbon monoxide, carbon dioxide, or any combination thereof.

This summary is not intended to identify essential features of the claimed subject matter, nor is it intended to be used to determine the scope of the claimed subject matter. It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide an overview or framework for understanding the nature and character of the disclosure.

Drawings

The accompanying drawings are incorporated in and constitute a part of this specification. It is to be understood that the drawings illustrate only some examples of the present disclosure, and that other examples or combinations of examples not specifically illustrated in the drawings are still possible within the scope of the present disclosure. Examples will now be described in further detail by using the accompanying drawings, in which:

fig. 1 (a) is a flowchart showing the progress of thermal runaway;

FIG. 1 (b) is a graph of thermal runaway and temperature;

FIG. 2 (a) is a typical battery pack in an electric vehicle;

FIG. 2 (b) is a diagram of a typical battery pack in an energy stationary storage housing;

FIG. 3 shows a battery thermal runaway detector;

FIG. 4 illustrates a typical battery cell before and after thermal runaway;

FIG. 5 is a graph of gases released from thermal runaway events in cells having different electrochemistry: LCO/NMC, NMC and LFP;

FIG. 6 is a plot of cascading thermal runaway propagation through a packet enclosure, where an initial cell triggers thermal runaway of several neighboring cells;

FIG. 7 is a plot of the hydrogen concentration rising immediately after initial venting followed by a slight rise in pressure within the enclosure within one minute thereafter as the gas expands beyond the package level venting capability;

FIG. 8 is a plot of thermal runaway initiation showing a rapid rise in carbon dioxide concentration within the enclosure; and is also provided with

Fig. 9 is a schematic diagram of a thermal runaway management system.

Detailed Description

In describing the illustrative, non-limiting embodiments shown in the drawings, specific terminology will be resorted to for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. Several embodiments are described for illustrative purposes, it being understood that the description and claims are not limited to the embodiments shown, and other embodiments not specifically shown in the drawings may be within the scope of the present disclosure.

The battery thermal runaway detector is pre-positioned within the void air space of a typical battery enclosure, such as that shown in fig. 3. The housing completely encloses one or more battery modules, each battery module having one or more battery cells aligned parallel or in series with each other. The battery cells of each module are in electrical communication with adjacent battery cells, and the battery modules are in electrical communication with each adjacent module. A battery controller communicates with each battery module and/or battery cell. The battery controller may operate each battery cell directly or through a module, such as turning on/off the battery cell or controlling the voltage output of each battery cell.

The housing protects the battery cells and modules from water, debris, and from electrical hazards within the housing. The housing void space volume (the volume of air space within the housing) can vary from as little as a few liters up to 200 liters or more, which typically contains air. The battery enclosure is typically provided with an air venting feature comprising a single or multiple small openings to achieve pressure equalization inside and outside the enclosure to prevent strain and damage to the package. These openings are typically protected by a hydrophobic membrane that allows air exchange but prevents liquid water from flowing directly into the housing. The housing may also contain a valve or similar device for safely venting excess pressure generated by thermal runaway from the housing, thereby reducing the risk of explosion and hazardous shrapnel.

Turning to fig. 9, a thermal runaway detector or detection system 100 is shown according to one non-limiting exemplary embodiment of the present disclosure. The detection system 100 resides within the cell housing void space as in fig. 3 and includes a primary detector, here a gas detector 110. The detection system 100 also includes a pressure sensor 112, a Relative Humidity (RH) sensor 114, and/or a temperature sensor 116.

In one embodiment of any of the detection systems described herein, the primary gas detector 100 includes one or more sensors for detecting decomposition products formed during thermal runaway.

For example, in one embodiment of any of the detection systems described herein, the primary gas detector 110 includes one or more sensors, and in one embodiment one or more of the following: CO ₂ Sensor, carbon monoxide (CO) sensor, HF sensor, H ₂ A gas sensor and/or a water vapor sensor.

In one embodiment of any of the detection systems described herein, the primary gas detector 110 comprises CO ₂ Sensor, CO sensor, HF sensor, H ₂ A gas sensor and a water vapor sensor.

In one embodiment of any of the detection systems described herein, the primary gas detector 110 comprises CO ₂ Sensor, CO sensor, HF sensor and H ₂ A gas sensor.

In another embodiment of any of the detection systems described herein, the primary gas detector 110 comprises CO ₂ Sensor, CO sensor, H ₂ A gas sensor and a water vapor sensor.

In another embodiment of any of the detection systems described herein, the primary gas detector 110 comprises CO ₂ Sensor, CO sensor and H ₂ A gas sensor.

In another embodiment of any of the detection systems described herein, the primary gas sensor 110 examines its unique physical properties without chemically interacting with the sensed gas, thereby providing a reliable and powerful primary sensor.

In another embodiment of any of the detection systems described herein, the primary gas detector 110 further comprises one or more secondary gas sensors for detecting one or more gases emitted from the battery cells prior to thermal runaway (e.g., during initial cell venting of the SEI decomposed gas products and electrolytes).

For example, in one embodiment of any of the detection systems described herein, the primary gas detector 110 further includes one or more secondary gas sensors for detecting one or more of the following: methane, ethane, oxygen, nitrogen oxides, volatile organic compounds, esters, hydrogen sulfide, sulfur oxides, ammonia, chlorine, propane, ozone, ethanol, hydrocarbons, hydrogen cyanide, combustible gases, flammable gases, toxic gases, corrosive gases, oxidizing gases, and/or reducing gases.

In another embodiment of any of the detection systems described herein, the primary gas detector 110 further comprises one or more secondary gas sensors for detecting one or more of the following: CH (CH) ₄ 、C ₂ H ₂ 、C ₂ H ₄ 、C ₂ H ₆ Diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylene Carbonate (EC), ethylmethyl carbonate (EMC), C ₄ H ₁₀ 、C ₃ H ₆ 、C ₃ H ₈ And/or POF ₃ 。

In one embodiment of any of the detection systems described herein, the gas detector 100 includes one or more primary sensors for detecting decomposition products formed during thermal runaway and one or more secondary gas sensors for detecting one or more gases emitted from the battery cells prior to thermal runaway (e.g., during initial cell venting of the decomposed gas products and electrolyte).

The detectors/sensors 110-116 are positioned around the housing and any suitable combination of detectors and/or sensors 110-116 may be utilized.

The thermal runaway detection system 100 also contains a voltage regulator 120 that provides and regulates power sufficient to operate the sensors 110-116, the microcontroller or microprocessor 118, and the communication transceiver 122. The sensor elements 110-116 are electrically connected to a microcontroller 118 within the detection system 100. The microcontroller 118 interprets the sensor output from each of the sensors 110-116 and provides the necessary signal conditioning to convert the raw sensor signal into an engineered value for each component. The values are then transmitted to a communication transceiver 122 that provides a data stream of sensor information to a battery management system master controller or other electronic monitoring system.

In the use of CO ₂ The gas sensor 110, as one of the primary gas sensors 110, detects carbon dioxide levels in the enclosure (fig. 3) and has long-term reliability and fast response time (within 6 seconds to record events). The carbon dioxide background concentration levels are generally below 1,000ppm, and these concentrations can easily exceed 60,000ppm within the housing during cell venting conditions, providing a very powerful gas signal for detection, as shown in fig. 8. In the case where the jet velocity during venting typically exceeds 200 meters/second, diffusion of carbon dioxide within the housing void space occurs very rapidly, reaching the gas sensor 110 in 2 seconds or less, whether or not the sensor is in close proximity to the venting battery cell.

In one embodiment of any of the detection systems described herein, a method for detecting CO ₂ Is an infrared (e.g., near-dispersive infrared) spectrum sensor.

For example, in one embodiment of any of the detection systems described herein, the gas sensor 110 provides an output to a processing device 118 that can determine whether the sensed condition exceeds a predetermined threshold or whether the sensed condition changes rapidly.

In one embodiment of any of the detection systems described herein, the predetermined threshold for detecting a concentration of carbon dioxide signaling a thermal runaway event is greater than about 1,000ppm, such as greater than about 10,000ppm, greater than about 20,000ppm, greater than about 30,000ppm, greater than about 40,000ppm, greater than about 50,000ppm, greater than about 60,000ppm, or greater than about 75,000ppm. In one embodiment of any of the detection systems described herein, the predetermined threshold for detecting carbon dioxide concentration signaling a thermal runaway event is greater than about 10,000ppm.

Thus, in one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event occurs when the concentration of carbon dioxide detected by the sensor is greater than about 1,000ppm, such as greater than about 10,000ppm, greater than about 20,000ppm, greater than about 30,000ppm, greater than about 40,000ppm, greater than about 50,000ppm, greater than about 60,000ppm, or greater than about 75,000ppm. In one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event occurs when the concentration of carbon dioxide detected by the sensor is greater than about 10,000ppm.

In a similar manner, the background concentration of hydrogen in the atmosphere is typically around 200-300 ppb. The hydrogen concentration inside the cell housing can easily exceed 140,000ppm under cell venting conditions, which also provides a strong signal-to-noise ratio for gas detection, as shown in fig. 7.

In one embodiment of any of the detection systems described herein, a method for detecting H ₂ Is a heat conduction sensor.

In one embodiment of any of the detection systems described herein, the predetermined threshold for detecting a hydrogen concentration signaling a thermal runaway event is greater than about 200ppb, such as greater than about 300ppb, greater than about 1ppm, greater than about 100ppm, greater than about 1,000ppm, greater than about 10,000ppm, greater than about 40,000ppm, greater than about 50,000ppm, greater than about 100,000ppm, or greater than about 150,000ppm. In one embodiment of any of the detection systems described herein, the predetermined threshold for detecting hydrogen concentration signaling a thermal runaway event trigger is greater than about 40,000ppm.

Thus, in one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event occurs when the concentration of hydrogen detected by the sensor is greater than 200ppb, such as greater than about 300ppb, greater than about 1ppm, greater than about 100ppm, greater than about 1,000ppm, greater than about 10,000ppm, greater than about 50,000ppm, greater than about 100,000ppm, or greater than about 150,000ppm. In one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event occurs when the concentration of hydrogen gas detected by the sensor is greater than 40,000ppm.

In one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event occurs when the concentration of hydrogen gas detected by the sensor is above its lower explosion limit (4%).

In one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event occurs when the concentration of CO detected by the sensor is above its dangerous limit and/or its lower explosion limit (12.5%).

Heat transfer and CO of hydrogen ₂ The principle of non-dispersive infrared measurement of primary sensors is used in powerful absolute measurement devices, which have limited cross sensitivity to other gases, making them ideal choices for such applications, where there is little or no opportunity to recalibrate or repair the device in the field. This is generally because the measurement principle is chosen based on the unique physical behavior of the gas molecules when they do not chemically interact with the target gas or other gases in the environment.

In one embodiment of any of the detection systems described herein, the secondary gas sensor is MO-based _x Or a Pellistor sensor (e.g., for detecting hydrocarbons).

The pressure sensor 112 detects the gas pressure level in the void space of the battery enclosure. The nominal gas pressure within the enclosure is approximately atmospheric pressure. During thermal runaway venting, if the venting phase is highly energetic, as in the case of a battery cell in a 100% state of charge as shown in fig. 6, the pressure may suddenly rise. The pressure rise initially accompanying this may be very low, especially in the case of smaller cells or cells having a much lower state of charge, as shown in fig. 8. When relying on a housing exhaust system, an increase in gas pressure or temperature may provide information about the rate of thermal runaway. The pressure sensor 112 is small and low cost, has a fast time response at low power consumption, but has been shown to provide poor data during a slow exhaust event where the battery enclosure exhaust system allows release of trapped gases at a rate that counteracts the gas generation. However, when used to supplement the gas sensor 110, the pressure sensor 112 may provide valuable insight regarding the progress of thermal runaway, as it cascades from the starting cell to the neighboring cell within the enclosure, as shown in fig. 6, in which case the continuous increase in hydrogen gas concentration and the accompanying pressure spike indicate that thermal runaway has progressed to the other cell, which leads to a cascade failure of the package.

Temperature sensor 116 detects the temperature within the housing void space and, like pressure sensor 112, may be used in conjunction with gas sensor 110 to estimate the rate of progression of thermal runaway (fig. 6). The gradual increase in temperature with each successive cell thermal runaway provides critical data to determine whether the reaction has stopped or is proceeding at a rate that requires immediate safety measures to be taken, such as providing protective countermeasures including, but not limited to, introducing water or fire extinguishing agents, actively cooling, introducing dilution air or nitrogen, and electrically isolating or discharging the suspected cell.

In one embodiment, the temperature sensor 116 detects a temperature in a range of about 100 ℃ to about 1200 ℃, such as about 600 ℃ to about 1000 ℃.

The relative humidity sensor 114 monitors the humidity within the void space of the enclosure and may also be used in conjunction with the gas sensor 110 to observe a significant change in water vapor within the enclosure that indicates the formation of water vapor due to the decomposition reaction products.

The detection system 100 may be used in a variety of suitable applications. In the embodiment shown in fig. 2 (a), 3, the detection system 100 is implemented in a vehicle having a battery housing, a power distribution unit, and a battery controller and/or Motor Control Unit (MCU). The battery case may be composed of a plurality of battery cells, and may be accommodated within the battery case.

The sensors 110-116 each output a sensed signal to a processing device, such as a microcontroller 118. The microcontroller 118 converts the analog sensor signal to an engineered value and transmits the data, such as in the form of an alarm signal or an output signal, to the battery management system via the wired or wireless transceiver 122. The microcontroller 118 may also determine whether the values from the sensors 110-116 exceed a critical threshold at which the sensors indicate cell venting, and provide algorithms to determine whether the sensors 110-116 are operating properly and within specifications. The detection system 100 may utilize redundant sensors 110-116 to meet the security index level.

One or more of the sensors 110-116 are located in free space within a battery housing (fig. 3) of the vehicle such that the sensors 110-116 communicate (e.g., gas or pressure communication) with the air space proximate the battery and/or battery compartment and receive and detect conditions caused by the battery cell venting. The sensors 110-116 provide outputs to the processing device 118, which may determine whether the sensed condition exceeds a predetermined threshold (i.e., if exceeded, a threshold that signals that thermal runaway-based cell venting has been initiated) or whether the sensed condition is changing rapidly. The entire system 100, including the sensors 110-116, microcontroller 118, regulator 120, and transceiver 122, may all be housed in a single sensor housing and positioned at one location in the battery compartment. In another embodiment, the system 100 may be a separate device each having its own housing, and each housing is positioned at a separate location in the battery compartment, including surface mounting on the battery management system electronics.

As shown and described, the detection system solves the problem of reliably detecting thermal runaway in lithium ion batteries, where the degassing precursor of thermal runaway can occur over a time span of seconds or hours. The detection system measures a plurality of physical parameters of the degassing event, which may allow for detection of fast thermal runaway as well as slower events. Multiple detection techniques reduce the risk of false positives and false negatives and provide sufficient redundancy to meet market safety requirements. The system measures at a minimum hydrogen and/or carbon dioxide concentration and may be supplemented with air pressure and or temperature and humidity within the enclosure.

In other variations, the detection system may also comprise hydrocarbon detection of the electrolyte, comprising methane, ester, and ethane gases. During initial cell venting prior to thermal runaway, the vented gas contains a concentration of H sufficient to be detected by a separate sensor ₂ 、CO、CO ₂ And hydrocarbons. By combining them into a single sensor platform with signal conditioning and analysis, it is possible to determine with relative certainty that an event is a single cell experiencing thermal runaway, and by monitoring the gas simultaneously, the difference between less urgent electrolyte leakage and a more urgent thermal runaway condition. Heat transfer and CO of hydrogen ₂ The use of the principle of non-dispersive infrared measurement of sensors is a powerful absolute measurement device with limited cross sensitivity to other gases, making it an ideal choice for such applications, where there is little or no opportunity to recalibrate or repair the device in the field.

Referring more particularly to fig. 6, an example runaway is shown. In this illustrative example, thermal runaway is cascaded from one cell to an adjacent cell. Starting from t=0, the battery system operates under normal conditions, and the hydrogen level 150, temperature 160, pressure 170 are all normal. At a first period t=1, the first single battery cell of the first battery module experiences thermal runaway. As a result, it releases gas, here hydrogen. The hydrogen sensor of the gas detector 110 measures the hydrogen level and has a sensed gas level output. Which transmits the sensed gas level output to the microcontroller 118. In addition, the pressure sensor 112 detects pressure and has a sensed pressure output. Which then transmits the sensed pressure output to the microcontroller 118. Further, the temperature sensor 116 measures the temperature in the housing and provides a sensed temperature output. Which transmits the sensed temperature output to the microcontroller 118.

The sensors 110-116 immediately send the sensed output to the microcontroller 118 in real time without delay or human intervention. The sensors 110-116 may send the sensed output to the microcontroller 118 continuously or intermittently at random or for a predetermined period of time, such as several times per second.

In the example embodiment of fig. 6, a cascading thermal runaway event is shown propagating through the packet enclosure, in which case the initial cell triggers thermal runaway in the neighboring cells. The microcontroller 118 receives sensed gas, pressure and temperature outputs from the gas sensor 110, the pressure sensor 112 and the temperature sensor 116, respectively. At t=1, both the hydrogen gas concentration 150 and the pressure 170 exhibit spikes. However, the temperature 160 increases only slightly. Venting in the cell housing rapidly dissipates the pressure 170 back to normal levels, but the hydrogen is vented more slowly and remains at an elevated level. Based on these conditions and the receipt of the sensed output, the microcontroller 118 determines that at least the first battery cell has experienced a thermal runaway event and generates an alert signal that it sends to the battery controller. For example, in response, the battery controller may take a first response, such as to indicate to an operator that maintenance is needed, to reduce the voltage requirements of the battery module, or to control the battery so that it does not become so hot.

At t=2 in the example embodiment of fig. 6, another battery cell undergoes thermal runaway. Here, the microprocessor 118 determines that there is another peak in the gas and pressure, respectively, based on the sensed outputs from the gas sensor 150 and the pressure sensor 160, and the temperature slightly increases again. Due to the exhaust conditions, the pressure returns to normal again quite rapidly, but the temperature and hydrogen levels continue to be in the ascending mode. Thus, the microprocessor 118 determines that another thermal runaway event has occurred and sends another alarm signal to the battery controller. The battery controller may continue to take the same response or may upgrade the response, such as by shortening the alarm response time, for example, by indicating that immediate maintenance is required, or by disconnecting one or more of the battery modules. The microcontroller 118 determines that there are additional spikes at t=3, 4. The various levels of gas, temperature, and pressure may vary based on the exhaust conditions and the particular thermal runaway event. For example, after t=4, the pressure may drop as the housing hydrophobic vent fails, but spike as additional cells within the housing fail with each successive cell thermal runaway event. The microcontroller 118 or battery controller may further determine that the event exists in a cascade mode and take additional responsive action. The responsive actions may be sent from the battery controller to the microcontroller 118 through the transceiver 122, which then controls the operation of the battery cells and modules.

Turning to fig. 7, another example thermal runaway event is illustrated. Here, the system 100 has a gas sensor 110, here a hydrogen sensor, and a pressure sensor 112. At t=1, the hydrogen concentration 150 rises immediately after the initial venting, followed by a slight increase in pressure 170 within the enclosure at t=2 (one minute after t=1) as the gas expands beyond the packet level venting capability. Thus, at t=1, the microprocessor 118 generates an alarm that thermal runaway has been initiated. The pressure rise at T2 in fig. 7 indicates a delayed response of the pressure signal in this example, where hydrogen gas above the lower exposure limit is present at T1, but the pressure does not increase significantly for more than one minute.

Turning to fig. 8, yet another example embodiment is shown. Here, the gas detector 110 is a carbon dioxide sensor. The plot shows that the carbon dioxide concentration 150 increases within the enclosure while the pressure 170 remains the same and the temperature 160 exhibits a slight increase. At t=2, the microcontroller 118 determines that thermal runaway has occurred and generates an alert to the battery controller of its party.

Thus, the microcontroller 118 uses sensed outputs from the gas sensor 110, the pressure sensor 112, the RH sensor 114, and/or the temperature sensor 116, respectively, to determine whether a thermal runaway event or other condition exists within the battery enclosure. The microcontroller 118 may be based on a determination of a single sensed output or a combination of sensed outputs. For example, the microcontroller 118 may determine that thermal runaway is likely to occur based on the presence of an individual gas spike and then reference the sensed pressure output and/or the sensed temperature output to determine whether the thermal runaway event is cascading to additional cells throughout the package by utilizing a combination of gas measurements to determine an initial thermal runaway event and monitoring the increase in pressure or temperature to evaluate the magnitude of the event. An increase in temperature or pressure within the package consistent with a high gas concentration level indicates that the countermeasure is not isolating the event to a single cell and generates an alert that escalates the response. For example, the initial alert may be to inform the vehicle owner to send the vehicle for repair as soon as possible, and the escalation alert may be to inform the vehicle occupant to drive the vehicle to the side of the road, leave the vehicle, and the BMS will shut down the vehicle except for the heat exchanger system in an attempt to slow down the process. However, if the temperature and pressure do not increase, the microcontroller 118 may determine that the thermal event has ceased and has been isolated to a single cell or group of cells and not generate an alert to escalate the response. Thus, in the example given, the alert will continue to inform the vehicle owner to service the vehicle.

It should be noted that the microcontroller 118 is configured to receive the sensed output, determine spikes, and send an alert to the battery controller via the transceiver 122. However, the microcontroller operation may instead be performed by the battery controller itself, and the sensed output may be transmitted to the battery controller through the transceiver. The response action signal may be sent directly from the battery controller to the battery unit through transceiver 122.

Advantages of the detection system 100 include, for example, the use of specific combinations of sensors to achieve layering of chemical and thermal-physical related detection mechanisms of phenomena associated with thermal runaway events using known validated and field proven sensor technologies. The system is rarely, if ever, customized for a variety of xEV case discovery/cell configurations/electrochemistry. The system also has a very fast time response (typically 3 to 5 seconds) in an environment where positive detection of thermal runaway requires a fast response with minimal risk of false-missing/false-detection. The system is compact and can operate in multiple modes to reduce parasitic power consumption when the battery enclosure is neither actively charging nor discharging. These modes may utilize information received from the battery management system within the sensor assembly 100 in active modes (driving or charging) where fast detection is critical and power consumption is less important or in passive modes where power consumption is critical and the sampling rate may be reduced to reduce device power consumption.

The systems and methods of the present invention include operations performed by one or more processing devices, including microprocessor 118. Note that the processing device may be any suitable device, such as a processor, microprocessor, controller, application Specific Integrated Circuit (ASIC), or the like. The processing device may be used in combination with other suitable components, such as a display device, memory or storage device, input device (touch screen), wireless module (for RF, bluetooth, infrared, wiFi, etc.). The information may be stored on a computer medium, such as a computer hard drive, or any other suitable data storage device that may be located on or in communication with the processing device. The whole process is automated by the processing means and does not require any human interaction. Thus, unless otherwise indicated, the process may occur in substantially real-time without any delay or manual operation.

In another aspect, the present disclosure is directed to a method of detecting thermal runaway of a battery (e.g., detecting thermal runaway of one or more battery cells) within a housing.

In one embodiment, the method comprises:

(i) Providing a detection system according to any of the embodiments described herein within the battery housing;

(ii) Measuring and/or analyzing one or more gases emitted from the cell;

(iii) It is determined whether the analyzed gas level is at or above a predetermined threshold level indicative of thermal runaway of the battery.

In one embodiment, the analyzed gas includes hydrogen, carbon monoxide, carbon dioxide, or any combination thereof.

In one embodiment, any of the detection systems and/or methods described herein do not perform the following steps: i) Receiving the sensor signal, ii) evaluating the sensor signal with respect to a threshold value, or iii) generating an alarm based on the result of the evaluation, or any combination of the foregoing.

In another embodiment, any of the detection systems and/or methods described herein does not monitor the ambient gas in the ambient gas environment.

It will be apparent to those skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings that modifications, combinations, sub-combinations, and variations can be made without departing from the spirit or scope of the disclosure. Likewise, each of the examples described may be used alone or in combination with other examples. Those skilled in the art will appreciate various combinations of examples not specifically described or illustrated herein that are still within the scope of the present disclosure. In this regard, it should be understood that the present disclosure is not limited to the particular examples set forth, and that the examples of the present disclosure are intended to be illustrative, rather than limiting.

As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Similarly, the adjective "another" when used to introduce elements is intended to mean one or more elements. The terms "comprising," "including," "having," and similar terms are intended to be inclusive such that there may be additional elements other than the listed elements.

Furthermore, no particular order is intended to be inferred, in the event that the method described above or the appended method claims do not explicitly require the order in which their steps are followed or no order is otherwise required based on the description or claim language. Also, where the appended method claims do not expressly refer to the steps mentioned in the above description, it should not be assumed that the claims require said steps.

Claims (20)

1. A battery thermal runaway detection sensor system for use within a battery enclosure housing one or more batteries, the sensor system comprising:

(i) At least one primary gas sensor for detecting a thermal runaway condition of the battery cell and providing a sensed output in real time; and

(ii) A microcontroller that determines power management and signals regarding the concentration of a particular battery thermal runaway gas based on the sensed output from the at least one primary gas sensor and provides the sensed output in real time.

2. The detection system of claim 1, wherein the system further comprises a secondary gas sensor for detecting an electrolyte leakage condition.

3. The detection system of claim 1 or claim 2, wherein the primary gas sensor comprises one or more of: CO ₂ Sensor, CO sensor, HF sensor, H ₂ A sensor and/or a water vapor sensor.

4. A detection system according to any one of claims 1 to 3, wherein the primary gas sensor comprises one or more of: CO ₂ Sensor, CO sensor and/or H ₂ A sensor.

5. The detection system of any one of claims 2 to 4, wherein the secondary gas sensor comprises a sensor for detecting one or more of: methane, ethane, oxygen, nitrogen oxides, volatile organic compounds, esters, hydrogen sulfide, sulfur oxides, ammonia, chlorine, propane, ozone, ethanol, hydrocarbons, hydrogen cyanide, combustible gases, flammable gases, toxic gases, corrosive gases, oxidizing gases, reducing gases, or any combination of any of the foregoing.

6. The detection system of any one of claims 2 to 5, wherein the secondary gas sensor comprises a sensor for detecting one or more of: CH (CH) ₄ 、C ₂ H ₂ 、C ₂ H ₄ 、C ₂ H ₆ Diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylene Carbonate (EC), ethylmethyl carbonate (EMC),C ₄ H ₁₀ 、C ₃ H ₆ 、C ₃ H ₈ 、POF ₃ Or any combination of any of the foregoing.

7. The detection system of any one of claims 2 to 6, wherein the at least one primary gas sensor detects the level of hydrogen gas, carbon monoxide gas and/or carbon dioxide gas in the cell compartment housing.

8. The detection system of any one of claims 1 to 7, further comprising at least one additional sensor for detecting a secondary condition of the battery and providing information in real time about a rate of progression of cell venting and thermal runaway, the information comprising pressure or temperature, wherein the microcontroller provides the rate of progression of thermal runaway based on the provided information from the secondary sensor.

9. The detection system of claim 8, wherein the at least one additional sensor detects pressure or temperature in the battery compartment housing to determine a rate of progression of exhaust/thermal runaway.

10. The detection system of any one of claims 1 to 9, further comprising a sensor housing that encloses the at least one sensor and the at least one secondary sensor.

11. The detection system of any one of claims 1 to 10, wherein the output from the primary and secondary gas sensors allows for distinguishing between electrolyte leakage and exhaust/thermal runaway.

12. The detection system of any one of claims 1 to 11, wherein system software is embedded within the sensor microcontroller to determine if a threshold level of thermal runaway has been exceeded and to send an alert to the battery management microcontroller or the charging system controller.

13. The detection system of claim 12, wherein the threshold level of thermal runaway is selected from the group consisting of:

(i) Carbon dioxide levels greater than about 10,000 ppm;

(ii) Hydrogen levels greater than about 40,000 ppm;

(iii) Carbon dioxide levels above its lower explosion limit;

(iv) Hydrogen levels above its lower explosion limit; and

(v) Any combination thereof.

14. The detection system according to any one of claims 1 to 13, which is constituted by a multi-chip printed circuit board to be mounted on a battery management controller printed circuit board.

15. The detection system of any one of claims 1 to 14, comprising a power management system that enables a fast data acquisition mode during active battery system charging/discharging and a reduced acquisition rate/lower power mode when the battery system is neither charging nor discharging.

16. The detection system of any one of claims 1 to 15, wherein the system is capable of sending a wake-up command to a master battery system controller upon detection of an exhaust/thermal runaway.

17. The detection system of any one of claims 1 to 16, wherein the sensor system comprises a plurality of gas sensors selected from more than one hydrogen sensor, more than one carbon monoxide sensor, more than one carbon dioxide sensor, and any combination of any of the foregoing to achieve redundancy in safety critical applications.

18. The detection system of any one of claims 1 to 17, wherein the system further comprises a humidity sensor, a pressure sensor, a temperature sensor, or any combination thereof.

19. A method of detecting a thermal runaway condition of a battery within a battery enclosure, the method comprising:

(i) Providing a detection system according to any one of claims 1 to 18 within the battery housing;

(ii) Measuring and/or analyzing one or more gases emitted from the cell;

(iii) It is determined whether the analyzed gas level is at or above a predetermined threshold level indicative of thermal runaway of the battery.

20. The method of claim 19, wherein the gas analyzed comprises hydrogen, carbon monoxide, carbon dioxide, or any combination thereof.