Battery module gas sensors for battery cell monitoring

Abstract

The present invention provides a battery monitoring system and method. The battery monitoring system may include a battery module and a battery management circuit. The battery module includes a battery cell and a gas sensor, and the gas sensor is configured to detect the presence of gas within the battery module. The battery management circuit is configured to receive a sensor signal from the gas sensor, determine whether the sensor signal indicates the presence of gas within the battery module, and take action in response to determining that the sensor signal indicates the presence of gas. The action may include increasing cooling of the battery cell, limiting the maximum load that can be applied to the battery module, disconnecting the battery module, or providing a warning. The battery module may also include a component doped with a chemical substance that begins to outgas above an activation temperature. The gas sensor may be configured to detect the chemical substance.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims the benefit of U.S. Provisional Application No. 62 / 808,220, filed on February 20, 2019, which is hereby incorporated by reference in its entirety. Summary of the invention

[0003] Battery modules with multiple battery cells are used in various applications. For example, electric vehicles may use battery modules with a large number of battery cells (e.g., hundreds or thousands of battery cells per module). It is important not to operate the battery module outside its safe operating area. When battery cells such as lithium-ion battery cells are operated above their safe operating temperature, damage may occur. As the temperature rises, pressure may accumulate in the battery cells. For example, the electrolyte gel inside the battery cell may begin to bubble or produce steam, which will cause the pressure inside the battery cell to increase. Battery cells typically have vents that allow gas or liquid to escape when the pressure increases beyond the actuation pressure of the vent. It is desirable to prevent the battery cells from reaching the point of ventilation. In addition, if the temperature inside the battery cell continues to rise, a thermal runaway event may occur. It is also desirable to prevent thermal runaway events.

[0004] The battery management system is used to monitor the operation of the battery modules to ensure that they are operated within a safe operating area. One way to monitor the temperature of the battery cells is to use a temperature sensor, such as a thermistor or a thermocouple. When the battery module contains multiple battery cells, multiple temperature sensors may be required to adequately monitor the temperature of the battery cells. In some systems, the thermal properties of the battery modules are modeled, and the model can be used to reduce the number of temperature sensors. However, such systems may not be able to detect local temperature increases over time to prevent damage to one or more battery cells. Therefore, it is desirable to identify local increases in temperature inside the battery module. It is also desirable to identify local temperature increases without using a temperature sensor for each battery cell. It is also desirable to predict and prevent potential battery cell ventilation. It is also desirable to detect the occurrence of battery cell ventilation. It is also desirable to predict and prevent thermal runaway events. According to some embodiments of the present disclosure, one or more gas sensors are used in a battery module to provide improved monitoring of the battery module.

[0005] In some embodiments, the battery monitoring system of the present disclosure may include a battery module and a battery management circuit. The battery module includes a plurality of battery cells and a gas sensor configured to detect the presence of gas within the battery module. The battery management circuit is configured to receive a sensor signal from the gas sensor, determine whether the sensor signal indicates the presence of gas within the battery module, and take action in response to determining that the sensor signal indicates the presence of gas.

[0006] In some embodiments, the action includes using a battery cooling system to provide increased cooling for the plurality of battery cells. In some embodiments, the action includes limiting a maximum load that can be applied to the battery module. In some embodiments, the action includes disconnecting the battery module from the load. In some embodiments, the action includes using a user interface to provide a warning.

[0007] In some embodiments, the battery module includes a component doped with a chemical. When the temperature of the component rises above an activation temperature, the component begins to outgas the chemical. In some embodiments, the gas sensor is configured to detect the chemical. In some embodiments, the component includes an adhesive for securing the plurality of battery cells in the battery module.

[0008] In some embodiments, the battery module includes a first gas sensor and a second gas sensor, wherein the first gas sensor is configured to detect at least one chemical indicative of battery cell overheating and the second gas sensor is configured to detect at least one chemical indicative of battery cell venting.

[0009] In some embodiments, the battery module includes a first gas sensor and a second gas sensor, wherein the first gas sensor is configured to detect at least one chemical indicative of battery cell venting and the second gas sensor is configured to detect at least one chemical indicative of battery cell thermal runaway.

[0010] In some embodiments, the battery management circuit is configured to determine whether the sensor signal indicates the presence of gas within the battery module by determining whether the sensor signal indicates a gas concentration greater than a threshold value.

[0011] In some embodiments, the battery management circuit is configured to determine a first battery module condition when the sensor signal indicates that the gas concentration is greater than a first threshold, and to determine a second battery module condition when the sensor signal indicates that the gas concentration is greater than a second threshold greater than the first threshold.

[0012] In some embodiments, the system further includes a temperature sensor, and the battery management circuit is configured to receive a temperature sensor signal from the temperature sensor and determine the battery module condition based on the sensor signal and the temperature sensor signal.

[0013] In some embodiments of the present disclosure, a battery monitoring method is provided. The method includes receiving a sensor signal from a gas sensor, the gas sensor being configured to detect the presence of gas within a battery module, wherein the battery module includes a plurality of battery cells. The method also includes determining, using a battery management circuit, whether the sensor signal indicates the presence of gas within the battery module, and taking an action in response to determining that the sensor signal indicates the presence of gas. In some embodiments, the action includes the actions discussed above.

[0014] In some embodiments, the method further comprises doping a component of the battery module with a chemical, wherein the component begins to outgas the chemical when the temperature of the component rises above an activation temperature. The method further comprises detecting the chemical using a gas sensor. In some embodiments, the component comprises an adhesive, and the method further comprises securing the plurality of battery cells in the battery module using the adhesive.

[0015] In some embodiments, the method includes receiving a first sensor signal and a second sensor signal from a first gas sensor and a second gas sensor. In some embodiments, the first gas sensor is configured to detect at least one chemical indicative of battery cell overheating, and the second gas sensor is configured to detect at least one chemical indicative of battery cell venting. In some embodiments, the first gas sensor is configured to detect at least one chemical indicative of battery cell venting, and the second gas sensor is configured to detect at least one chemical indicative of a battery cell thermal runaway event.

[0016] In some embodiments, determining whether the sensor signal indicates the presence of gas within the battery module includes determining whether the sensor signal indicates a gas concentration greater than a threshold.

[0017] In some embodiments, determining whether the sensor signal indicates the presence of gas within the battery module includes determining a first battery module condition when the sensor signal indicates that the gas concentration is greater than a first threshold, and determining a second battery module condition when the sensor signal indicates that the gas concentration is greater than a second threshold greater than the first threshold. In some embodiments, taking an action includes taking a first action in response to determining the first battery module condition, and taking a second action in response to determining the second battery module condition.

[0018] In some embodiments, the method further includes receiving a temperature sensor signal from a temperature sensor and determining a battery module condition based on the sensor signal and the temperature sensor signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present disclosure according to one or more various embodiments is described in detail with reference to the following drawings. The drawings are provided for illustrative purposes only and depict only typical or exemplary embodiments. These drawings are provided to facilitate understanding of the concepts disclosed herein and should not be considered to limit the breadth, scope or applicability of these concepts. It should be noted that for clarity and ease of illustration, these drawings are not necessarily drawn to scale.

[0020] Figure 1 shows an illustrative plot of gas concentrations in a battery module according to some embodiments of the present disclosure;

[0021] Figure 2 shows a block diagram of an exemplary battery module 200 according to some embodiments of the present disclosure;

[0022] Figure 3 shows an illustrative plot of gas concentration and temperature in a battery module according to some embodiments of the present disclosure;

[0023] Figure 4 An illustrative plot showing gas concentrations and adjustable thresholds in a battery module according to some embodiments of the present disclosure; and

[0024] Figure 5 A system diagram of an illustrative battery system 100 for use in an electric vehicle is shown, according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0025] According to the present disclosure, a gas sensor is provided in a battery module to determine the battery module status. In some embodiments, the gas sensor is used to determine the temperature of the battery cell. In some embodiments, the gas sensor is used to predict a battery cell ventilation event. In some embodiments, the gas sensor is used to detect the occurrence of a battery cell ventilation event. In some embodiments, the gas sensor is used to predict the occurrence of thermal runaway. In some embodiments, the gas sensor is used to detect the occurrence of a thermal event.

[0026] Battery cell venting is a hazardous event that can cause explosions and fires, which can then propagate to other nearby battery cells. In electric vehicle design, it is important to prevent battery cell venting through mechanical design and software control. If these mechanisms are not sufficient, it is useful to detect venting events in order to, for example, warn the driver and safely shut down vehicle power.

[0027] Testing was conducted to analyze conditions inside a battery module when cells were purposefully overheated to induce cell venting. Overheating of the battery cells was accomplished using Nichrome wire. Gas sensors were included inside the battery module enclosure. Review of the test data showed, for example, that the detected gas concentration increased steadily for up to 20 minutes before the heated cell actually vented. The lithium-ion battery cells vented at approximately 130°C. As testing progressed, the cells were heated from ambient temperature to 130°C, and the gas concentration increased perceptibly between 100°C and 130°C.

[0028] It is believed that the cell releases gas before full venting, or something in thermal contact with the cell releases gas. For example, gas may be released when a material melts or when a material is heated and begins to outgas.

[0029] Figure 1 An illustrative drawing 100 of gas concentration in a battery module according to some embodiments of the present disclosure is shown. Drawing 100 is a simplified drawing showing gas concentration as the temperature of a battery cell increases. As shown, drawing 100 is divided into four temperature regions. The first temperature region is the safe operating region. In this region, the temperature of the battery cell is in its normal operating region. As shown, the gas concentration is negligible. The second temperature region is the cell overheat region. In this region, the temperature of the battery cell is higher than its normal operating temperature. At the low end of the cell overheat region, the gas concentration is still negligible. As the battery cell temperature increases in the battery overheat region, the gas concentration begins to increase at a relatively low rate until the temperature reaches the cell vent region. In the cell vent region, the pressure inside the battery cell exceeds the activation pressure of its vent, and the battery cell begins to discharge gas and / or liquid into the battery module. As shown, the gas concentration increases at a higher rate in the cell vent region. The last temperature region is the thermal runaway region. In this region, overheating of the battery cell can damage the internal structure of the battery, resulting in a short circuit. This can then cause a fire and possibly an explosion. In this region, the battery cell temperature and the gas concentration in the battery module increase rapidly.

[0030] It should be understood that the specific temperature area and gas concentration of the battery module will be determined based on the specific battery cells used and the overall design of the battery module. For example, different types of batteries experience ventilation and thermal runaway at different temperatures. As another example, the internal volume of the battery module will affect the gas concentration level. It should also be understood that the battery module can be designed to achieve the desired relationship between the battery cell temperature and the gas concentration. For example, in some battery modules, the battery cells are fixed inside the battery module using an adhesive. The adhesive may be in direct contact with the battery cells, and some adhesives release volatile organic compounds (VOCs) when the adhesive is heated above a certain temperature. For example, the adhesive may begin to emit steam at about 100°C, which is lower than the battery cell ventilation temperature. Therefore, an adhesive can be selected to provide an advance warning of potential battery cell ventilation. This advance warning enables one or more actions to be taken to prevent damage to the battery cell.

[0031] In some embodiments, materials may be added to the battery module to obtain a desired relationship between gas concentration and battery cell temperature. For example, one or more components of the battery module (e.g., an adhesive) may be doped with a chemical such that when the temperature of the component increases above an activation temperature, the component begins to outgas the chemical so that it can be detected with a gas sensor. As another example, a component may be added to the battery module to begin outgassing at a desired temperature. Such components (e.g., a gel or adhesive) may be added to the outside of the battery cell to enable accurate identification of localized overheating.

[0032] In some embodiments, by detecting a specific chemical signature (e.g., using an appropriately matched gas sensor substrate) and measuring its concentration, the concentration can be correlated to one or more specific temperature points. Thus, a single sensor can provide complete coverage for all cells in a battery module. For example, a battery module can be modeled or designed so that the gas concentration measured by a single sensor is correlated to one or more expected battery cell temperatures.

[0033] Figure 2 A block diagram of an exemplary battery module 200 according to some embodiments of the present disclosure is shown. The battery module 200 includes a plurality of battery cells 202 arranged in two layers, with a cooling plate 204 positioned between the two layers. In some embodiments, the ends of the battery cells 202 are fixed to the cooling plate 204 via an adhesive. The adhesive can provide good physical and thermal coupling between the battery cells 202 and the cooling plate 204. The cooling plate 204 extends beyond the outer housing of the battery module 200 on one side and includes input and output ports. Figure 2The cooling system not shown in the figure provides the supplied cooling fluid to the input port of the cooling plate 204 and receives the returned cooling fluid from the output port. The flow rate and / or temperature of the cooling fluid are controlled by the cooling system. The cooling system maintains the temperature of the battery cell 202 within the normal operating temperature range during operation.

[0034] The battery module 200 also includes gas sensors 206a and 206b and temperature sensors 208a and 208b. Gas sensors 206a and 206b can be any suitable gas sensors for detecting the gas emitted when the temperature of one or more of the battery cells 202 rises beyond its normal temperature range. As shown, the gas sensor 206a is positioned at the top of the battery module. In some embodiments, this position is preferred because hot air rises and the gas emitted due to overheating is expected to rise as well. This position can enable gas to be detected faster than other positions. As shown, the gas sensor 206b is positioned at the bottom of the battery module. In some embodiments, the positioning of the cooling plate 204 can make this position preferred in the lower half of the battery module. When the hot air rises, the cooling plate 204 will cool the air at the top of the lower half of the battery module and cause convective airflow to occur, thereby moving the emitted gas through the gas sensor 206b. The temperature sensors 208a and 208b can be positioned at any suitable position for measuring the temperature within the battery module 200. Although the temperature sensor may not immediately detect a local temperature increase in the battery cell, it can detect such an increase if the local temperature increase persists. Therefore, the gas concentration and one or more temperature readings can be used together to determine the condition of the battery module. It should be understood that the design and layout of the battery module 200 are merely illustrative and the sensors may be positioned in any suitable location. In some embodiments, one or more guides may be used to direct the flow of thermal energy toward the location of the gas sensor or multiple gas sensors. It should also be understood that although the battery module 200 is shown as having two layers of battery cells 202, more or fewer layers of battery cells may be used. It should also be understood that more or fewer gas and temperature sensors may be used. In some embodiments, the battery module includes a single layer of battery cells and a single gas sensor.

[0035] Figure 3Illustrative plots of gas concentration and temperature in a battery module according to some embodiments of the present disclosure are shown. Plot 300 is a simplified plot showing gas concentration 302 in a battery module over time. Plot 310 is a simplified plot showing temperature 312 in a battery module over time. The time axes of plots 300 and 310 are aligned and correspond to the same time. Before time t1, gas concentration 302 and temperature 312 remain at relatively constant levels, which can correspond to a battery module operating in a normal operating region. Between time t1 and time t2, gas concentration 302 begins to increase, while temperature 312 remains at its constant level. During this time interval, the battery module may begin to experience a battery cell overheat condition, but before the overheat is reflected at the temperature sensor. At time t2, temperature 312 also begins to rise, so after time t2, both gas concentration 302 and temperature 312 are rising. This can correspond to a battery cell overheat condition continuing or getting worse.

[0036] Drawing 300 depicts two thresholds, a lower threshold 304a and an upper threshold 304b. In some embodiments, when the gas concentration 302 crosses the upper threshold 304, a battery module condition (e.g., a battery overheat event) can be declared. For example, the upper threshold 304 can be selected so that when the gas concentration 302 crosses this threshold, the battery module condition can be declared with high confidence. In some embodiments, by using temperature 312 in combination with gas concentration 302, the battery module condition can be detected earlier with high confidence. For example, when the gas concentration 302 crosses the lower threshold 304a but is lower than the upper threshold 304b, the temperature 312 can be analyzed to determine whether to declare the battery module condition with high confidence. In some embodiments, a comparison of temperature changes or temperature levels to a threshold value can be used in conjunction with the gas concentration 302. For example, the battery module condition may be declared when the gas concentration 302 crosses a threshold (e.g., the lower threshold 304a) and one of the following conditions is met: (1) the slope of the temperature 312 is positive; (2) the slope of the temperature 312 is greater than the threshold; (3) the temperature 312 is greater than the threshold, or a combination thereof.

[0037] As described above, the gas sensor can be any suitable gas sensor for detecting gases emitted when the temperature of a battery cell rises beyond its normal temperature range. Such gas sensors can detect (a) gas emissions from the adhesive when the battery cell is in an overheated condition, (b) gases emitted from the battery cell during ventilation, and (c) gases emitted during thermal runaway. In some embodiments, multiple gas sensors tuned in different ways are used to detect different types of gases. A first gas sensor can be used to detect gas emissions from an adhesive (e.g., an adhesive doped with a chemical). A second gas sensor can be used to detect gases (e.g., CO, CO2, and H2) emitted during cell ventilation and thermal runaway. A third gas sensor can be used to detect gases emitted during cell ventilation and thermal runaway. In some embodiments, a single gas sensor can be configured to independently detect different types of gases.

[0038] In some embodiments, one or more gas concentration thresholds may be used to determine battery module conditions. For example, a threshold may be set to identify when a battery module enters a battery cell overheating region, but before the battery cell reaches ventilation. Such a threshold may be set at below Figure 1 When the gas concentration is below the threshold, the battery module condition is determined to be normal. When the gas concentration is above the threshold, the battery module condition is determined to be in a battery cell overheat condition, which predicts the onset of cell ventilation. A second higher threshold may be used to identify when cell ventilation occurs. For example, such a threshold may be set at Figure 1 When the gas concentration is above a second higher threshold, the battery module condition is determined to be in a cell venting condition, which predicts the onset of a thermal runaway event. A third higher threshold may be used to identify when a thermal runaway event occurs. Such a threshold may be set above Figure 1 The level of the upper horizontal dashed line.

[0039] In some embodiments, the gas concentration in the battery module may change during normal operation of the battery module. For example, the longer the battery module operates, the gas concentration may gradually increase. As another example, the gas concentration may also increase under heavy load. Therefore, the use and condition of the battery module can be monitored, and the threshold value can be adjusted according to the use. For example, if it is expected that the gas concentration will gradually increase during the continuous operation of the battery module, one or more threshold values ​​can also be gradually increased. As another example, when the battery module is not in use, the gas concentration in the battery module is expected to decrease over time. Therefore, one or more threshold values ​​can be reduced based on the last reading of the gas concentration and the time when the battery module is not in use. By adjusting one or more threshold values ​​based on the operating conditions of the battery module, false alarms can be eliminated. The expected normal change in gas concentration can be determined by operating the battery module under a range of normal operating conditions and observing the change in gas concentration.

[0040] Figure 4 An illustrative drawing 400 of a gas concentration 402 and an adjustable threshold 404 in a battery module according to some embodiments of the present disclosure is shown. Drawing 400 is a simplified drawing showing changes in gas concentration 402 over time when the battery module is under a load (e.g., a relatively constant load). As shown, the threshold 404 varies over time and can therefore be adjusted based on the operating conditions of the battery module. In some embodiments, a battery management circuit is used to determine the adjustable threshold. For example, the adjustable threshold can be determined by first calculating the expected gas concentration in the battery module based on the load over time and information about how the battery module is expected to operate under the load, and then adding an offset (e.g., a fixed amount or a percentage amount). Figure 4 , threshold 404 increases linearly over time under a relatively constant load. By using an adjustable threshold (e.g., based on expected gas concentrations), a battery overheat event can be quickly predicted or identified. The gas concentration 402 in the battery module increases linearly as expected before time t1. However, at time t1, the gas concentration 402 begins to increase at a faster rate, indicating that a battery overheat condition may be imminent. At time t2, the gas concentration 402 crosses the adjustable threshold 404. At this point, the battery management circuit can declare a battery module condition (e.g., a battery overheat event) and take one or more actions as described herein.

[0041] The battery module of the present disclosure, for example Figure 2 The battery module 200 can be used in various applications. For example, the battery module can be used for grid energy storage. As another example, the battery module can be used in an electric vehicle.

[0042] Figure 5A system diagram of an exemplary battery system 500 for use in an electric vehicle according to some embodiments of the present disclosure is shown. The battery system 500 includes one or more battery modules 502 coupled to an electric vehicle subsystem 510. In some embodiments, each of the one or more battery modules 502 includes a plurality of battery cells. In some embodiments, the one or more battery modules 502 each correspond to Figure 2 A battery module 200 is provided. Figure 3 The electric vehicle subsystems depicted in are exemplary, and additional or fewer subsystems may be included in an electric vehicle. It should be understood that the electric vehicle subsystem may include circuits for performing functions. In some embodiments, the circuit may include hardware (e.g., one or more ASICs) or a combination of hardware and software (e.g., one or more hardware CPUs for executing software instructions stored in a memory) or a combination thereof. As shown, the electric vehicle subsystem includes a battery management system 512, one or more electric drive units 514, a battery cooling system 516, and a user interface 518.

[0043] The battery management system 512 monitors and controls the operation of the battery module 502. The battery management system 512 receives sensor signals from the battery module 502. In some embodiments, the battery management system 512 receives sensor signals from gas sensors (e.g., Figure 2 In some embodiments, the battery management system 512 receives sensor signals from gas sensors and temperature sensors (e.g., Figure 2 The temperature sensors 208a and 208b of the battery module 208a and 208b receive the sensor signals. The battery management system 512 (e.g., the battery management circuit) evaluates the sensor signals and determines the condition of the battery module. When the condition of the battery module exceeds its normal operating condition, the battery management system 512 can take one or more actions.

[0044] The battery cooling system 516 provides cooling for one or more battery modules 502. In some embodiments, the battery cooling system 516 provides cooling fluid to each battery module independently. The battery management system 512 is configured to control the battery cooling system 516 to maintain the one or more battery modules 502 within a normal temperature range.

[0045] One or more electric drive units 514 provide propulsion to the electric vehicle. When the electric vehicle is rapidly accelerated, the one or more electric drive units 514 provide a large load on the one or more battery modules 502. This may cause the temperature of the battery modules to increase. The battery management system 512 can respond to the large load by causing the battery cooling system 516 to provide increased cooling to the battery modules 502. For example, the coolant flow rate can be increased and / or the coolant temperature can be reduced to remove the heat generated by the large load.

[0046] The user interface 518 can be any suitable user interface. In some embodiments, the user interface includes a display screen (e.g., a dashboard display). For example, the display screen can be an LCD display, an OLED display, and an LED display or any other type of display. In some embodiments, the user interface includes a speaker. The user interface can operate under the control of the battery management system 512 to present information (e.g., visual and / or audio information) to the user.

[0047] According to the present disclosure, the battery management system 512 can use one or more gas sensors to correlate gas concentrations with battery cell temperatures. By monitoring gas concentrations, the battery management system 512 is able to determine in which temperature region (e.g., a safe operating region, a cell overheat region, a cell vent region, or a thermal runaway region) the battery cell is operating as explained above. In some embodiments, the battery management circuit is configured to receive a sensor signal from a gas sensor, determine whether the sensor signal indicates the presence of gas within the battery module (e.g., by combining the sensor signal with the above Figure 1 , 3 and 4) and in response to determining that the sensor signal indicates the presence of gas, takes action. In some embodiments, the battery management circuit adjusts the threshold value based on the use of the battery module. When the presence of gas indicates that the battery module is in a cell overheat condition, this predicts the start of cell ventilation. Depending on the cause of the cell overheat, this determination can provide sufficient time (e.g., a few minutes or up to 20 minutes or more) to prevent the occurrence of ventilation.

[0048] The battery management circuit may take one or more actions to prevent ventilation from occurring. For example, the battery management circuit may perform one or more of the following actions: increase cooling (e.g., by instructing the battery cooling system to increase cooling); reduce the current in the battery module (e.g., by limiting the maximum load that can be applied to the battery module); provide a warning to the user (e.g., display a warning or alarm using a user interface); and disconnect the battery module (e.g., by activating a contactor coupled to the electrical output of the battery module). In some embodiments, if the gas concentration continues to increase, the battery management circuit may take action progressively. For example, the battery management circuit may first increase cooling. If the gas concentration continues to increase, the battery management circuit may additionally reduce the current in the battery module. If the gas concentration continues to increase, the battery management circuit may display a warning to the user. If the gas concentration continues to increase, the battery management circuit may disconnect the battery module to shut down the vehicle. In some embodiments, when the battery cell is operating in a cell overheating region, the battery management circuit may take one or more first actions (e.g., try to prevent cell ventilation), and when the battery cell is operating in a cell ventilation region, one or more second actions may be taken (e.g., try to prevent thermal runaway). When the battery cell is operating in the thermal runaway region, the battery management circuit may take one or more third actions (eg, disconnecting the battery).

[0049] It should be understood that the battery management circuit may evaluate the gas concentration of a single gas sensor or the concentration of multiple gas sensors (each gas sensor is configured to detect a different type of gas) to determine in which temperature zone the battery cell is operating. It should also be understood that the battery management circuit may receive one or more additional sensor signals (e.g., a temperature sensor signal or a pressure sensor signal) to evaluate additional information to determine the temperature of the battery cell. For example, if the battery cell is slowly overheating, the gas concentration may first begin to increase, then the temperature reading of the temperature sensor may begin to increase, and then the pressure reading from the pressure sensor may begin to increase after ventilation or thermal runaway (e.g., a large pressure increase may occur after ventilation, and a large pressure increase again after thermal runaway). Therefore, by using information from one or more additional sensors, the battery management circuit is able to more accurately determine the temperature of the battery cell and more accurately predict the start of cell ventilation or thermal runaway. For example, if the gas concentration increases at a slow rate and crosses a threshold, the battery management circuit may not be sure that the battery cell is operating in the cell overheating zone unless the temperature reading also indicates an increase in temperature. However, if there is a relatively rapid increase in gas concentration (e.g., a high rate of change), the battery management circuitry may determine that the battery cell is operating in a cell overheat region, regardless of whether the temperature reading indicates an elevated temperature. Thus, the battery management circuitry may use both gas concentration and gas concentration changes to determine battery module conditions.

[0050] It should also be understood that the techniques of the present disclosure can relate the concentration of a detected gas (e.g., released from an adhesive) measured by a single gas sensor to the temperature of that material. By proxy, the techniques of the present disclosure also enable the concentration to be related to the battery cell temperature. Thus, the battery cell temperature can be determined based on the presence of gas in the battery module (e.g., when the material is configured to outgas at a specific temperature) or the concentration of gas in the battery module (e.g., based on empirical data that relates battery cell temperature to gas concentration).

[0051] The technology of the present disclosure provides various improvements to the design and operation of battery modules. In a battery module, unless each individual cell in the module has its own temperature sensor measurement, there will always be incomplete temperature sensing coverage. For battery modules equipped with a large number of battery cells, it is impractical to provide each battery cell with its own temperature sensor. When not every battery cell has its own temperature sensor, the battery cell temperature measurements are inferred or modeled, making it difficult or impossible to detect localized or individual cell temperature increases prior to cell ventilation. The use of the gas sensor of the present disclosure overcomes these problems and provides early warning of the onset of cell ventilation, thereby enabling action to be taken to reduce the possibility of cell ventilation and thermal runaway.

[0052] The foregoing is merely an illustration of the principles of the present disclosure, and various modifications may be made by those skilled in the art without departing from the scope of the present disclosure. The above embodiments are provided for illustration rather than limitation. In addition to the forms explicitly described herein, the present disclosure may also take many forms. Therefore, it should be emphasized that the present disclosure is not limited to the methods, systems, and devices explicitly disclosed, but is intended to include variations and modifications of the present invention within the spirit of the following claims.

Claims

1. A battery system, comprising: A battery module, the battery module comprising: a plurality of battery cells; a component thermally coupled to the plurality of battery cells, wherein the component is configured to release a gas when a temperature of the component rises above an activation temperature that is lower than a cell venting temperature range, wherein the cell venting temperature range initiates venting of at least one of the plurality of battery cells; and a gas sensor configured to detect the presence of the gas within the battery module; and A battery management circuit, the battery management circuit being configured to: receiving a sensor signal from the gas sensor; determining whether the sensor signal indicates that the gas is present in the battery module; and In response to determining that the sensor signal indicates the presence of the gas, an action is taken.

2. The system according to claim 1, further comprising: A battery cooling system is configured to provide cooling to the plurality of battery cells, wherein the actions include providing increased cooling to the plurality of battery cells using the battery cooling system.

3. The system according to claim 1, wherein: The action includes one of limiting a maximum load that can be applied to the battery module and disconnecting the battery module from a load.

4. The system according to claim 1, further comprising: A user interface, wherein the action comprises providing an alert using the user interface.

5. The system of claim 1, wherein: The components are doped with chemical substances; When the temperature of the component rises above the activation temperature, the component begins to outgas the chemical; and The gas sensor is configured to detect the chemical substance.

6. The system according to claim 5, wherein: The component includes an adhesive for fixing the plurality of battery cells in the battery module.

7. The system according to claim 1, wherein: The gas sensor includes a first gas sensor configured to detect at least one chemical substance indicative of overheating of the battery cell, the battery module further comprising: A second gas sensor is configured to detect at least one chemical species indicative of battery cell venting.

8. The system according to claim 1, wherein: The gas sensor includes a first gas sensor configured to detect at least one chemical substance indicative of battery cell venting, the battery module further comprising: A second gas sensor is configured to detect at least one chemical species indicative of a battery cell thermal runaway event.

9. The system according to claim 1, wherein: The battery management circuit is configured to determine whether the sensor signal indicates that the gas is present in the battery module by: A determination is made as to whether the sensor signal indicates that a concentration of the gas is greater than a threshold value.

10. The system according to claim 1, wherein: The battery management circuit is configured to: When the sensor signal indicates that the concentration of the gas is greater than a first threshold, determining a first battery module condition; and A second battery module condition is determined when the sensor signal indicates that the concentration of the gas is greater than a second threshold that is greater than the first threshold.

11. The system of claim 1 , further comprising: At least one temperature sensor, wherein: The battery management circuit is configured to: receiving at least one temperature sensor signal from the at least one temperature sensor; and A battery module condition is determined based on the sensor signal and the at least one temperature sensor signal.

12. A battery monitoring method, the method comprising: releasing gas from a component thermally coupled to a plurality of battery cells when a temperature of the component rises above an activation temperature that is lower than a cell venting temperature range, wherein the cell venting temperature range initiates venting of at least one of the plurality of battery cells; receiving a sensor signal from a gas sensor configured to detect the presence of a gas within a battery module, wherein the battery module includes the plurality of battery cells; determining, using battery management circuitry, whether the sensor signal indicates that the gas is present in the battery module; and In response to determining that the sensor signal indicates the presence of the gas, an action is taken.

13. The method according to claim 12, wherein: Taking the action includes providing increased cooling to the plurality of battery cells using a battery cooling system.

14. The method according to claim 12, wherein: Taking the action includes one of limiting a maximum load that can be applied to the battery module and disconnecting the battery module from a load.

15. The method according to claim 12, wherein: Taking the action includes providing an alert using a user interface.

16. The method according to claim 12, further comprising: doping the component of the battery module with a chemical, wherein the component begins to outgas the chemical when the temperature of the component rises above an activation temperature; and The chemical substance is detected using the gas sensor.

17. The method according to claim 16, wherein: The component includes an adhesive, and the method further includes: The plurality of battery cells are fixed in the battery module using the adhesive.

18. The method according to claim 12, wherein: The gas sensor includes a first gas sensor configured to detect at least one chemical substance indicative of overheating of the battery cell, the method further comprising: A second sensor signal is received from a second gas sensor configured to detect at least one chemical species indicative of cell venting.

19. The method according to claim 12, wherein: The gas sensor includes a first gas sensor configured to detect at least one chemical indicative of battery cell venting, the method further comprising: A second sensor signal is received from a second gas sensor configured to detect at least one chemical species indicative of a battery cell thermal runaway event.

20. The method according to claim 12, wherein: Determining whether the sensor signal indicates that the gas is present within the battery module includes determining whether the sensor signal indicates that a concentration of the gas is greater than a threshold.

21. The method of claim 12, wherein: Determining whether the sensor signal indicates that the gas is present in the battery module includes: When the sensor signal indicates that the concentration of the gas is greater than a first threshold, determining a first battery module condition; and determining a second battery module condition when the sensor signal indicates that the concentration of the gas is greater than a second threshold value that is greater than the first threshold value; and Taking said actions includes: taking a first action in response to determining the first battery module condition; and A second action is taken in response to determining the second battery module condition.

22. The method of claim 12, further comprising: receiving at least one temperature sensor signal from at least one temperature sensor; as well as A battery module condition is determined based on the sensor signal and the at least one temperature sensor signal.

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