Sample coupled chemistor for thermal event detection

Abstract

The present disclosure provides a "sample-coupled chemiresistor for thermal event detection". A battery thermal event detection system includes a battery, a chemiresistor, and a temperature-sensitive sample in contact with a surface of the battery. The sample is configured to release a gas configured to change the resistance of the chemiresistor in response to a change in the battery temperature. The system also includes a controller coupled to the chemiresistor and configured to reduce the power supplied by the battery in response to detecting that a change in the resistance is greater than a threshold change.

Description

Technical Field

[0001] The present disclosure relates to temperature management of a high voltage traction battery. Background Art

[0002] Overheating of battery cells can lead to the emission of undesirable gases such as hydrogen, methane and carbon monoxide. Therefore, temperature measurement within a high-voltage traction battery pack is critical to detect when a cell exceeds its maximum operating temperature. However, in a conventional battery pack, it may not be possible to detect a single thermal event because a limited number of thermistors typically measure the average temperature of multiple cells. In addition, monitoring the temperature of all cells in the battery pack would increase the cost and complexity of the system. Summary of the invention

[0003] According to one embodiment, a battery thermal event detection system is disclosed. The battery thermal event detection system includes a battery, a chemiresistor, and a temperature-sensitive sample in contact with a surface of the battery. The sample is configured to release a gas configured to change the resistance of the chemiresistor in response to a change in the battery temperature. The system also includes a controller coupled to the chemiresistor and configured to reduce the power supplied by the battery in response to detecting a resistance change greater than a threshold change.

[0004] According to one or more embodiments, the change in battery temperature may correspond to a change in a predetermined threshold temperature that exceeds the sample release gas. The sample may be a single-phase chemical. In other embodiments, the sample may be a compound sample containing chemical substances on a supporting medium. In addition, the supporting medium may include at least one layer of porous material. The at least one layer of porous material may be activated carbon, molecular sieve, zeolite, porous PTFE, metal-organic framework or encapsulation material. In one or more embodiments, the controller may also be configured to terminate the power supplied by the battery in response to detecting a change in the resistance of the chemiresistor. When the resistance change of the chemiresistor is greater than a predetermined resistance threshold change, the controller may detect this change. In one or more embodiments, the chemiresistor may be a metal oxide semiconductor, a conductive polymer or a nanomaterial. In some embodiments, the nanomaterial may be graphene, carbon, a nanotube or a nanoparticle.

[0005] According to one embodiment, a method for controlling a battery thermal event detection system is disclosed. The method includes: in response to a temperature change in the battery, releasing gas from a temperature sensitive sample contacting a surface of the battery to change the resistance of a chemi-resistor; and reducing, by a controller, power supplied by the battery in response to detecting that the resistance change exceeds a predetermined resistance change, thereby reducing or stopping heat generation.

[0006] According to one or more embodiments, reducing may include terminating the power supplied by the battery. Releasing may include causing the chemical substance to evolve from a bound state to a vapor or gas state. In some embodiments, the chemical substance in a bound state may be stored in a support medium having at least one layer.

[0007] According to one embodiment, a system for monitoring the temperature of a battery pack is disclosed. The system includes: at least one battery cell, a chemi-resistor having a certain resistance within the battery pack, and at least one temperature-sensitive sample. Each sample corresponds to and contacts each battery cell, and the sample is configured to release gas to change resistance in response to a change in battery cell temperature. The system also includes a controller coupled to the chemi-resistor and configured to reduce the power supplied by the battery pack in response to detecting a resistance change greater than a threshold change.

[0008] According to one or more embodiments, the change in the temperature of the battery cell may correspond to the battery cell reaching a threshold temperature at which the sample releases gas. The sample may be a single-phase chemical. In other embodiments, the sample may be a compound sample containing a chemical on a supporting medium. The supporting medium may include at least one layer of porous material. The at least one layer may be activated carbon, a molecular sieve, a zeolite, a porous PTFE, a metal-organic framework, or an encapsulating material. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1A A partial schematic diagram of a battery thermal event detection system according to one embodiment is shown.

[0010] Figure 1B A partial schematic diagram of a battery thermal event detection system according to one embodiment is shown.

[0011] Figure 2A A schematic diagram of a battery pack according to one embodiment is shown.

[0012] Figure 2B A schematic diagram of a battery pack according to another embodiment is shown.

[0013] Figure 3A A schematic diagram of a battery thermal event detection system according to an embodiment is shown.

[0014] Figure 3B A schematic diagram of a battery thermal event detection system according to an embodiment is shown. DETAILED DESCRIPTION

[0015] As required, detailed embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the present invention, and the present invention may be embodied in various alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show the details of a particular component. Therefore, the specific structural details and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to adopt the present invention in different ways.

[0016] According to one embodiment, a battery thermal event detection system is disclosed. The system couples a chemiresistor to a temperature-sensitive sample containing a chemical substance and in contact with one or more battery cells. When the heat transferred from one or more overheated battery cells causes the sample temperature to exceed the threshold temperature of the exhaust, the chemical substance will evolve from a bound state to a gaseous state as a gas (or vapor). The presence of the chemical substance causes the ohmic resistance of the chemiresistor to change. The system of this embodiment replaces multiple connections and sensors with chemical substances, which transmit information about thermal events from one or more battery cells to a controller through the atmosphere within the battery pack, thereby reducing cost and complexity. The system of this embodiment will allow the controller to take appropriate action to reduce the heat generated by the flow of current when the battery exceeds a given temperature threshold, and will prevent operation under overheating conditions. By using a single hard-wired sensor coupled to a volatile chemical substance, production costs can be reduced, safety can be improved, and performance can be enhanced.

[0017] refer to Figure 1A -B, shows a partial schematic diagram of a battery thermal event detection (or interchangeably, thermal management) system 100 according to one embodiment. A battery surface 110 is in contact with a temperature sensitive sample 120. The battery surface 110 may be any surface of a battery cell. The battery surface 110 and the temperature sensitive sample 120 of a battery cell may be sealed within a battery pack containing one or more battery cells. Each battery cell may have a temperature sensitive sample 120 in contact with the surface 110. The temperature sensitive sample 120 contains a chemical substance. During normal operation, i.e., at normal operating temperature, the chemical substance is in a combined phase (e.g., condensed or absorbed). When the battery exceeds its maximum operating temperature (T max, for example 80°C), as reflected by the temperature change of surface 110, the chemical substance is thermally released from sample 120 in a gaseous or vaporous state. The chemical substance in sample 120 can be a single-phase chemical substance on a supporting medium or a compound sample containing a chemical substance. The supporting medium can be, but is not limited to, a layered material having at least one layer of porous material, such as activated carbon, molecular sieves, zeolites, porous PTFE, metal-organic frameworks, or encapsulating materials (e.g., microspheres). Various forms of such materials are commercially available, including films, powders, papers, pastes, or tapes that can be easily attached to battery cells. The compound sample containing the chemical substance can be prepared by saturating the supporting medium by controlled exposure of the supporting medium to a liquid phase, vapor phase, or gas phase of the chemical substance. In certain embodiments, the chemical substance can be, but is not limited to, carbon dioxide, methane, toluene, hydrogen, alkanes, or organic solvents. The release temperature of sample 120 is the temperature at which the chemical substance evolves from a bound state to a gaseous or vaporous state, in which case the chemical substance is released within the battery pack. Temperature-specific release can be based on selected phase transitions (i.e., liquid-gas, solid-gas); desorption from porous adsorbents (e.g., activated carbon, molecular sieves); or outgassing from microspheres. The materials used are selected so that the release temperature corresponds to the T of the battery. max .

[0018] The battery thermal event detection system 100 also includes a chemi-resistor 130. The system 100 including the sample 120 and the chemi-resistor 130 can be in a sealed battery pack where chemicals can quickly reach detectable concentration levels while maintaining a level that is safe for both people and equipment. The chemi-resistor 130 can be based on various technologies, such as but not limited to metal oxide semiconductors, conductive polymers, and nanomaterials, such as graphene, carbon nanotubes, and nanoparticles. The chemi-resistor 130 is installed in the battery pack, and the resistance of the chemi-resistor is monitored by a controller. The controller can be a stand-alone controller, a battery energy control module (BECM), or a controller that communicates with the BECM. Figure 1B As shown in FIG, during a thermal event (where the battery temperature exceeds T max) chemical gases or vapors released by the sample 120 diffuse into the chemiresistor 130 and change its resistance. Above Tmax, a relatively small amount (e.g., <1000ppm) of chemical substances diffuses within the battery pack and causes the chemiresistor to change its ohmic resistance. Below Tmax, there is no gas or vapor within the battery pack, and the chemiresistor 130 maintains a nominal resistance. The BECM measures the resistance change of the chemiresistor 130, and the BECM takes appropriate action to prevent further heating of the battery cell. If a smaller resistance change is measured, a Wheatstone bridge can be used. When the BECM measures a considerable change in the resistance of the chemiresistor 130, the BECM can open the battery contactor or cut off the power supplied to the contactor. The BECM can also limit the amount of current being output by the battery in order to reduce the power consumption generated as heat in the battery cell (e.g., Joule heating). Alternatively, the chemiresistor 130 can be placed in an interlock circuit, and the BECM opens the contactor under similar conditions. Since the power supplied by the battery generates heat (Joule heating, P = RI) when current flows through the battery cells 2 ), so reducing or terminating the power supplied by the battery can prevent the risk of overheating of the battery cells.

[0019] Figure 2A Schematic diagram of a battery cell module 200 according to one embodiment is shown. A battery pack may include one or more battery cell modules 200. The battery cell module 200 includes individual battery cells 210 having a battery cell surface. In this embodiment, each battery cell 210 has a temperature sensitive sample 220 contacting the surface. In another embodiment, as Figure 2B As shown, the module 200 includes individual battery cells 210 having surfaces. In this embodiment, a single temperature sensitive sample 220 spans across the surface of each battery cell 210. Figure 2A -B, the sample is located on the top surface of the battery cell 210, but this illustration is not intended to be limiting and the temperature sensitive sample 220 may be placed on any surface of the battery cell 210.

[0020] Figure 3A and Figure 3B Shown is the inclusion Figure 2ASchematic diagram of a battery thermal event detection system 300 of an embodiment of the present invention, wherein each battery cell 310 has its own contact surface temperature sensitive sample 320. A sealed battery pack 305 includes the battery cells 310 and the temperature sensitive sample 320. A chemi-resistor 330 is also within the battery pack 305 and is connected to a controller (or BECM) 335. Within the normal operating temperature range of the battery pack 305, the chemi-resistor has a resistance R. When a single battery cell of the battery pack 305 overheats and the temperature reaches T max When a voltage drop is detected, chemical 340 is released within battery pack 305, as shown by cell 325. Chemical 340 changes the resistance of chemical-sensitive resistor 330, which is monitored by BECM 335. Upon receiving or detecting the change in resistance (by comparing to a predetermined resistance threshold change), the BECM can reduce or shut off the power supplied by battery pack 305. Figure 2B In the depicted embodiment, although not shown in the figure, similar thermal events in a single battery cell will similarly release chemicals. In this way, the system 300 can learn when a single battery cell within the battery pack is overheated. Although not shown, the battery thermal event detection system of this embodiment is able to detect thermal events in multiple battery cells because the sample will release gas from multiple battery cells when overheated. The system will detect the gas through the resistance change of the chemical sensitive resistor and reduce or terminate the power supplied by the battery.

[0021] The battery thermal event detection system disclosed herein can improve the driving range and available power of electric vehicles. The battery cell temperature is controlled in a safe and cost-effective manner because it couples a chemistor and a temperature-sensitive sample and involves one (or optionally, multiple) sensors to monitor multiple battery cells in a battery pack. In addition, the thermal event detection system does not need to include additional wires because the occurrence of a thermal event is indicated by the chemical substances via the atmosphere within the battery pack. The battery thermal event detection system provides versatility in thermal management because individual battery cells or other components can be monitored. As a non-limiting example, the battery thermal event detection system can be used on any type of battery or battery pack, including but not limited to high-voltage traction batteries, stationary energy storage devices, fuel cells, consumer electronics, and aerospace.

[0022] Although exemplary embodiments are described above, this does not mean that these embodiments describe all possible forms of the present invention. Rather, the words used in this specification are descriptive rather than restrictive, and it should be understood that various changes can be made without departing from the spirit and scope of the present invention. In addition, the features of various implementation embodiments can be combined to form other embodiments of the present invention.

[0023] According to the present invention, a battery event detection system is provided, the system comprising: a battery, a chemiresistor, a temperature-sensitive sample in contact with the surface of the battery and configured to release a temperature-sensitive sample configured to change the resistance of the chemiresistor in response to a change in the battery temperature, and a controller coupled to the chemiresistor and configured to reduce the power supplied by the battery in response to detecting a resistance change greater than a threshold change.

[0024] According to one embodiment, the change in battery temperature corresponds to a change above a predetermined threshold temperature at which the sample releases gases.

[0025] According to one embodiment, the sample is a single phase chemical substance.

[0026] According to one embodiment, the sample is a compound sample comprising a chemical substance on a support medium.

[0027] According to one embodiment, the supporting medium comprises at least one layer of porous material.

[0028] According to one embodiment, at least one layer of porous material is activated carbon, molecular sieve, zeolite, porous PTFE, metal-organic framework or encapsulation material.

[0029] According to one embodiment, the controller is further configured to terminate power supplied by the battery in response to detecting a change in resistance of the chemistor.

[0030] According to one embodiment, when the resistance change of the chemiresistor is greater than a predetermined resistance threshold change, the controller may detect the change.

[0031] According to one embodiment, the chemiresistor is a metal oxide semiconductor, a conductive polymer or a nanomaterial.

[0032] According to one embodiment, the nanomaterial is graphene, carbon, nanotubes or nanoparticles.

[0033] According to the present invention, a method for controlling a battery thermal event detection system releases gas from a temperature sensitive sample contacting a battery surface to change the resistance of a chemi-resistor in response to a temperature change in the battery; and a controller reduces power supplied by the battery in response to detecting that the resistance change exceeds a predetermined resistance change, thereby reducing or stopping heat generation.

[0034] According to one embodiment, reducing includes terminating power supplied by the battery.

[0035] According to one embodiment, releasing includes evolving the chemical substance from a bound state to a vapor or gaseous state.

[0036] According to one embodiment, the chemical species in a bound state are stored in a support medium having at least one layer.

[0037] According to the present invention, a system for monitoring the temperature of a battery pack is provided, the system having at least one battery cell, a chemi-resistor having a certain resistance within the battery pack, at least one temperature-sensitive sample, and a controller, each of the samples corresponding to and in contact with each battery cell and configured to release gas to change the resistance in response to a change in the battery cell temperature, the controller being coupled to the chemi-resistor and configured to reduce the power supplied by the battery pack in response to detecting a resistance change greater than a threshold change.

[0038] According to one embodiment, the change in the battery cell temperature corresponds to the battery cell reaching a threshold temperature at which the sample releases gas.

[0039] According to one embodiment, the sample is a single phase chemical substance.

[0040] According to one embodiment, the sample is a compound sample comprising a chemical substance on a support medium.

[0041] According to one embodiment, the supporting medium comprises at least one layer of porous material.

[0042] According to one embodiment, at least one layer is activated carbon, a molecular sieve, a zeolite, a porous PTFE, a metal-organic framework or an encapsulating material.

Claims

1. A battery thermal event detection system, comprising: Batteries; Chemical sensitive resistor; a temperature sensitive sample in contact with a surface of the battery and configured to release a gas configured to change the resistance of the chemiresistor in response to a battery temperature exceeding a maximum operating temperature of the battery; as well as A controller is coupled to the chemistor and is configured to reduce power supplied by the battery in response to detecting that the resistance change is greater than a threshold change.

2. The battery thermal event detection system of claim 1, wherein the battery temperature exceeding the maximum operating temperature of the battery corresponds to a change exceeding a predetermined threshold temperature at which the sample releases the gas.

3. The battery thermal event detection system as described in claim 1, wherein the sample is a single-phase chemical substance. 4 . The battery thermal event detection system as claimed in claim 1 , wherein the sample is a compound sample containing chemical substances on a supporting medium. 5 . The battery thermal event detection system as claimed in claim 4 , wherein the supporting medium comprises at least one layer of porous material. 6 . The battery thermal event detection system as claimed in claim 5 , wherein the at least one layer of porous material is activated carbon, molecular sieve, zeolite, porous PTFE, metal-organic framework or encapsulation material. 7 . The battery thermal event detection system of claim 1 , wherein the controller is further configured to terminate power supplied by the battery in response to detecting a change in resistance of the chemi-resistor.

8. The battery thermal event detection system of claim 1, wherein when a resistance change of the chemiresistor is greater than a predetermined resistance threshold change, the controller detects the change.

9. The battery thermal event detection system as claimed in claim 1, wherein the chemiresistor is a metal oxide semiconductor, a conductive polymer or a nanomaterial. 10 . The battery thermal event detection system according to claim 9 , wherein the nanomaterial is graphene, carbon, nanotubes or nanoparticles.

11. A method for controlling a battery thermal event detection system, comprising: releasing a gas from a temperature sensitive sample contacting a surface of the battery to change the resistance of a chemiresistor in response to a temperature in the battery exceeding a maximum operating temperature of the battery; as well as Power supplied by the battery is reduced by a controller in response to detecting that the change in resistance exceeds a threshold change in resistance, thereby reducing or stopping heating.

12. The method of claim 11, wherein the reducing comprises terminating power supplied by the battery.

13. The method of claim 11, wherein the releasing comprises evolving the chemical substance from a bound state to a vapor or gaseous state.

14. The method of claim 13, wherein the chemical species in the bound state is stored in a supporting medium having at least one layer.

Images