Method, device and system for determining thermal runaway of battery

Abstract

The embodiment of the invention discloses a method, a device and a system for determining thermal runaway of a battery. The battery thermal runaway determination method comprises the following steps: acquiring the real-time surface temperature of a target battery; when the real-time surface temperature exceeds a preset temperature threshold value, acquiring impedance data of a preset frequency point; converting the impedance data of the preset frequency point into temperature data based on a relation function of impedance and temperature of the preset frequency point; determining the temperature rise rate of the target battery according to the temperature data; and when the temperature rise rate exceeds a preset temperature rise rate threshold, determining that the target battery is in thermal runaway. According to the battery thermal runaway determination method, device and system provided by the embodiment of the invention, the battery thermal runaway determination efficiency can be ensured, and the battery thermal runaway can be found in time.

Description

Technical Field

[0001] Embodiments of the present invention relate to battery technology, and in particular, to a method, device and system for determining thermal runaway of a battery. Background Art

[0002] With the development of the new energy industry, batteries are being used more and more widely. At the same time, the safety of battery use has also received widespread attention. One of the most important safety issues is thermal runaway of the battery. Therefore, in order to avoid the harm caused by the failure to detect thermal runaway of the battery in time, it is necessary to determine whether the battery has thermal runaway in time.

[0003] At present, the existing methods for determining battery thermal runaway usually detect whether the voltage changes suddenly or use sensors to detect temperature to determine whether the battery is in thermal runaway. However, voltage mutations only indicate that thermal runaway is caused by an internal short circuit in the battery, and using sensors to detect temperature requires heat conduction, which has a certain time delay and cannot detect thermal runaway as early as possible. In addition, by performing sweep frequency measurement on the battery, each test requires sweep frequency measurement, which takes too long, affects work efficiency, and there is a problem that thermal runaway cannot be detected as early as possible. Summary of the invention

[0004] Embodiments of the present invention provide a method, device and system for determining battery thermal runaway, so as to ensure the efficiency of determining battery thermal runaway and timely discover battery thermal runaway.

[0005] In a first aspect, an embodiment of the present invention provides a method for determining thermal runaway of a battery, comprising:

[0006] Obtain the real-time surface temperature of the target battery;

[0007] When the real-time surface temperature exceeds a preset temperature threshold, acquiring impedance data at a preset frequency point;

[0008] Based on the relationship function between the impedance and the temperature at the preset frequency point, converting the impedance data at the preset frequency point into temperature data;

[0009] Determining a temperature rise rate of the target battery according to the temperature data;

[0010] When the temperature rise rate exceeds a preset temperature rise rate threshold, it is determined that the target battery is in thermal runaway.

[0011] Optionally, before obtaining the real-time surface temperature of the target battery, the method includes:

[0012] Obtaining electrochemical impedance spectra of the target battery at different temperatures;

[0013] The preset temperature threshold, the preset frequency point, and a relationship function between the impedance and the temperature at the preset frequency point are determined according to the electrochemical impedance spectrum.

[0014] Optionally, determining the preset temperature threshold and the preset frequency point and the relationship function between the impedance and temperature at the preset frequency point according to the electrochemical impedance spectrum includes:

[0015] According to the electrochemical impedance spectrum, the lowest temperature value among the temperatures at which the impedance variation with temperature in the electrochemical impedance spectrum exceeds a preset variation threshold is used as the preset temperature threshold;

[0016] The frequency point corresponding to the preset change threshold value at which the impedance change exceeds the preset change threshold value at each temperature value higher than the preset temperature threshold value is taken as the preset frequency point;

[0017] A relationship function between the impedance at the preset frequency point and each temperature higher than the preset temperature threshold is established.

[0018] Optionally, the converting the impedance data at the preset frequency point into temperature data based on the relationship function between the impedance at the preset frequency point and the temperature includes:

[0019] According to the relationship function, the impedances corresponding to the preset frequency points at at least two different times are converted into corresponding temperatures to obtain the temperatures at at least two different times.

[0020] Optionally, after determining that the target battery has thermal runaway, the method further includes:

[0021] A warning prompt of thermal runaway of the target battery is issued.

[0022] Optionally, the target battery is a lithium-ion battery.

[0023] In a second aspect, an embodiment of the present invention provides a device for determining thermal runaway of a battery, comprising:

[0024] A temperature acquisition module is used to obtain the real-time surface temperature of the target battery;

[0025] An impedance acquisition module, used to acquire impedance data at a preset frequency point when the real-time surface temperature exceeds a preset temperature threshold;

[0026] a temperature determination module, configured to convert the impedance data at the preset frequency point into temperature data based on a relationship function between the impedance and the temperature at the preset frequency point;

[0027] A rate determination module, used to determine the temperature rise rate of the target battery according to the temperature data;

[0028] The thermal runaway determination module is used to determine that the target battery is in thermal runaway when the temperature rise rate exceeds a preset temperature rise rate threshold.

[0029] Optionally, the battery thermal runaway determination device further includes:

[0030] An impedance spectrum acquisition module, used to acquire the electrochemical impedance spectrum of the target battery at different temperatures;

[0031] The function determination module is used to determine the preset temperature threshold and the preset frequency point and the relationship function between the impedance and the temperature at the preset frequency point according to the electrochemical impedance spectrum.

[0032] In a third aspect, an embodiment of the present invention provides a battery thermal runaway determination system, comprising a collection module and a controller, wherein the collection module is communicatively connected to the controller, and the device as described in the second aspect is integrated in the controller.

[0033] Optionally, the acquisition module includes a temperature sensor and an EIS (Electrochemical Impedance Spectroscopy) measurement unit, the temperature sensor is used to collect the temperature of the target battery, and the EIS measurement unit is used to collect real-time impedance data of the target battery.

[0034] The method, device and system for determining thermal runaway of a battery provided by an embodiment of the present invention include: obtaining the real-time surface temperature of the target battery; when the real-time surface temperature exceeds a preset temperature threshold, obtaining impedance data at a preset frequency point; based on the relationship function between the impedance and the temperature at the preset frequency point, converting the impedance data at the preset frequency point into temperature data; determining the temperature rise rate of the target battery according to the temperature data; and determining that the target battery is in thermal runaway when the temperature rise rate exceeds the preset temperature rise rate threshold. The method, device and system for determining thermal runaway of a battery provided by an embodiment of the present invention determine the temperature rise rate of the target battery based on the relationship function between the impedance and the temperature at the preset frequency point, and when the temperature rise rate exceeds the preset temperature rise rate threshold, the target battery is determined to be in thermal runaway, without the need for frequency sweep measurement, which solves the problem of too long time caused by frequency sweep measurement in the prior art, and the problem of error delay in the temperature detected by the temperature sensor when thermal runaway occurs when the temperature sensor is used alone to detect the real-time surface temperature of the battery in the prior art, thereby ensuring the efficiency of determining thermal runaway of the battery so as to timely discover the thermal runaway of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a flow chart of a method for determining battery thermal runaway provided in Embodiment 1 of the present invention;

[0036] Figure 2 is a flow chart of a method for determining battery thermal runaway provided in Embodiment 2 of the present invention;

[0037] Figure 3This is a structural block diagram of a device for determining battery thermal runaway provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0039] Embodiment 1

[0040] Figure 1 1 is a flow chart of a method for determining battery thermal runaway provided in Embodiment 1 of the present invention. This embodiment can be applied to aspects such as early warning of thermal runaway of batteries such as lithium-ion batteries. The method can be executed by a device for determining battery thermal runaway. The device can be integrated in a controller of a system for determining battery thermal runaway. The controller can be implemented in the form of software and / or hardware. The method specifically includes the following steps:

[0041] Step 110: Obtain the real-time surface temperature of the target battery.

[0042] The target battery may be a lithium-ion battery, the different temperatures may include 0-300 degrees Celsius, and the state of charge SOC of the target battery may be between 80% and 20%. The real-time surface temperature of the target battery may be detected by a temperature sensor, and the battery thermal runaway determination device is electrically connected to the temperature sensor to obtain the real-time surface temperature of the target battery.

[0043] In addition, before obtaining the real-time surface temperature of the target battery, obtain the electrochemical impedance spectrum of the target battery at different temperatures; according to the electrochemical impedance spectrum, determine the preset temperature threshold and the preset frequency point and the relationship function between the impedance and the temperature at the preset frequency point. Specifically, the lowest temperature value among the temperatures where the impedance change with temperature in the electrochemical impedance spectrum exceeds the preset change threshold is taken as the preset temperature threshold; the frequency point corresponding to the impedance change exceeding the preset change threshold at each temperature value higher than the preset temperature threshold is taken as the preset frequency point; establish the relationship function between the impedance at the preset frequency point and each temperature higher than the preset temperature threshold. The relationship function between impedance and temperature can be obtained by fitting such as linear fitting or by other methods, which are not limited here.

[0044] Step 120: When the real-time surface temperature exceeds a preset temperature threshold, impedance data at a preset frequency point is obtained.

[0045] Specifically, the real-time impedance data of the target battery can be detected by an EIS measurement unit, and the battery thermal runaway determination device is electrically connected to the EIS measurement unit to obtain the real-time impedance data of the target battery at a preset frequency point.

[0046] Step 130: based on the relationship function between the impedance and the temperature at the preset frequency point, convert the impedance data at the preset frequency point into temperature data.

[0047] Specifically, the relationship function between the impedance and the temperature at the preset frequency point may be an inverse proportional function or a composite function, which may be determined according to the actual changes in the impedance and the temperature, and is not limited here. The impedance data at the preset frequency point is substituted into the relationship function between the impedance and the temperature at the preset frequency point to obtain the corresponding temperature data.

[0048] Step 140: Determine the temperature rise rate of the target battery according to the temperature data.

[0049] Specifically, different impedance data correspond to different temperature data. For example, the ratio of the difference between the temperature data corresponding to two impedance data to the time difference corresponding to the difference between the temperature data is the temperature rise rate.

[0050] Step 150: When the temperature rise rate exceeds a preset temperature rise rate threshold, determine that the target battery is in thermal runaway.

[0051] Exemplarily, the preset temperature rise rate threshold is 3 degrees Celsius per second. If the current temperature rise rate of the target battery exceeds the preset temperature rise rate threshold, it can be determined that the target battery is in thermal runaway. At this time, a thermal runaway early warning prompt can be issued to prompt relevant personnel to take corresponding measures in time.

[0052] It should be noted that the specific values ​​of the above-mentioned preset thresholds and target thresholds can be determined according to the actual battery thermal runaway test requirements and are not limited here.

[0053] The method for determining thermal runaway of a battery provided in the present embodiment comprises: obtaining the real-time surface temperature of a target battery; when the real-time surface temperature exceeds a preset temperature threshold, obtaining impedance data at a preset frequency point; based on a relationship function between impedance and temperature at the preset frequency point, converting the impedance data at the preset frequency point into temperature data; determining the temperature rise rate of the target battery according to the temperature data, and determining that the target battery is in thermal runaway when the temperature rise rate exceeds the preset temperature rise rate threshold. Only a single frequency point is required, and no frequency sweep measurement is required, which solves the problem of too long time caused by frequency sweep measurement in the prior art, and the problem that in the prior art, only a temperature sensor is used to detect the real-time surface temperature of the battery, and when thermal runaway occurs, the temperature detected by the temperature sensor has an error delay, thereby ensuring the efficiency of determining thermal runaway of the battery so as to timely detect thermal runaway of the battery.

[0054] Embodiment 2

[0055] Figure 2: is a flow chart of a method for determining battery thermal runaway provided in Embodiment 2 of the present invention. This embodiment can be applied to aspects such as early warning of thermal runaway of batteries such as lithium-ion batteries. The method can be executed by a device for determining battery thermal runaway. The device can be integrated in a controller of a system for determining battery thermal runaway. The controller can be implemented in the form of software and / or hardware. The method specifically includes the following steps:

[0056] Step 210: Obtain the real-time surface temperature of the target battery.

[0057] The target battery may be a lithium-ion battery, and the different temperatures may include 0-300 degrees Celsius. The state of charge SOC of the target battery may be between 80% and 20%. The real-time surface temperature of the target battery may be detected by a temperature sensor, and the battery thermal runaway determination device is electrically connected to the temperature sensor to obtain the real-time surface temperature of the target battery.

[0058] In addition, before obtaining the real-time surface temperature of the target battery, obtain the electrochemical impedance spectrum of the target battery at different temperatures; according to the electrochemical impedance spectrum, determine the preset temperature threshold and the preset frequency point and the relationship function between the impedance and the temperature at the preset frequency point. Specifically, the lowest temperature value among the temperatures where the impedance change with temperature in the electrochemical impedance spectrum exceeds the preset change threshold is taken as the preset temperature threshold; the frequency point corresponding to the impedance change exceeding the preset change threshold at each temperature value higher than the preset temperature threshold is taken as the preset frequency point; establish the relationship function between the impedance at the preset frequency point and each temperature higher than the preset temperature threshold. The relationship function between impedance and temperature can be obtained by fitting such as curve fitting or by other methods, which are not limited here.

[0059] Step 220: When the real-time surface temperature exceeds a preset temperature threshold, impedance data at a preset frequency point is obtained.

[0060] Specifically, the real-time impedance data of the target battery can be detected by an EIS measurement unit, and the battery thermal runaway determination device is electrically connected to the EIS measurement unit to obtain the real-time impedance data of the target battery.

[0061] Step 230: Based on the relationship function between the impedance and the temperature at the preset frequency point, the impedance corresponding to the preset frequency point at at least two different times is converted into the corresponding temperature to obtain the temperature at at least two different times.

[0062] Exemplarily, the relationship function between impedance and temperature is an inverse proportional function or a composite function, impedance is negatively correlated with temperature, and impedance decreases as temperature increases. The interval between two different times is short, at the order of seconds.

[0063] Step 240: Determine the temperature rise rate of the target battery according to the temperatures at at least two different times.

[0064] Specifically, the temperature at two different times is subtracted to obtain the temperature difference, and the ratio of the temperature difference to the time difference is used as the temperature rise rate.

[0065] Step 250: When the temperature rise rate exceeds a preset temperature rise rate threshold, determine that the target battery is in thermal runaway.

[0066] For example, the temperature rise rate threshold is preset at 3 degrees Celsius per second. When the temperature rise rate exceeds the preset temperature rise rate threshold, an early warning of thermal runaway of the target battery may be issued to prompt relevant staff to take corresponding measures in a timely manner.

[0067] It should be noted that the specific values ​​of the parameters in this embodiment can be determined according to the actual thermal runaway test requirements and are not limited here.

[0068] The method for determining battery thermal runaway provided in the present embodiment determines the temperature rise rate of the target battery based on the relationship function between the impedance and the temperature at a preset frequency point. When the temperature rise rate exceeds the preset temperature rise rate threshold, the target battery is determined to be thermally runaway. Only a single frequency point is required, and no frequency sweep measurement is required. This solves the problem that the time taken for frequency sweep measurement in the prior art is too long, and the problem that the temperature detected by the temperature sensor has error delay when thermal runaway occurs when only the temperature sensor is used to detect the real-time surface temperature of the battery in the prior art. This ensures the efficiency of determining battery thermal runaway, so that battery thermal runaway can be discovered in a timely manner.

[0069] Embodiment 3

[0070] Figure 3 : is a structural block diagram of a battery thermal runaway determination device provided by Embodiment 3 of the present invention. Figure 3 The battery thermal runaway determination device includes: a temperature acquisition module 310, an impedance acquisition module 320, a temperature determination module 330, a rate determination module 340 and a thermal runaway determination module 350. The temperature acquisition module 310 is used to acquire the real-time surface temperature of the target battery; the impedance acquisition module 320 is used to acquire the impedance data at a preset frequency point when the real-time surface temperature exceeds the preset temperature threshold; the temperature determination module 330 is used to convert the impedance data at the preset frequency point into temperature data based on the relationship function between the impedance and the temperature at the preset frequency point; the rate determination module 340 is used to determine the temperature rise rate of the target battery according to the temperature data; and the thermal runaway determination module 350 is used to determine the thermal runaway of the target battery when the temperature rise rate exceeds the preset temperature rise rate threshold.

[0071] On the basis of the above implementation, the battery thermal runaway determination device further includes:

[0072] An impedance spectrum acquisition module, used to acquire the electrochemical impedance spectrum of the target battery at different temperatures before the temperature acquisition module 310 acquires the real-time surface temperature of the target battery;

[0073] The function determination module is used to determine the preset temperature threshold and the preset frequency point and the relationship function between the impedance and the temperature at the preset frequency point according to the electrochemical impedance spectrum.

[0074] In one embodiment, the function determination module includes:

[0075] A threshold determination unit, for determining, according to the electrochemical impedance spectrum, the lowest temperature value among the temperatures at which the impedance variation with temperature in the electrochemical impedance spectrum exceeds a preset variation threshold value as a preset temperature threshold value;

[0076] A frequency point determination unit, used to take the frequency point corresponding to the preset change threshold value at each temperature value higher than the preset temperature threshold value as the preset frequency point;

[0077] The function determination unit is used to establish a relationship function between the impedance at a preset frequency point and each temperature higher than a preset temperature threshold.

[0078] Optionally, the temperature determination module 330 is specifically configured to convert the impedances corresponding to the preset frequency points at at least two different times into corresponding temperatures according to the relationship function, so as to obtain the temperatures at at least two different times.

[0079] Optionally, the thermal runaway determination module 340 is further configured to issue a warning of thermal runaway of the target battery after determining that the target battery is in thermal runaway.

[0080] This embodiment also provides a battery thermal runaway determination system, including an acquisition module and a controller, the acquisition module is in communication with the controller, and the battery thermal runaway determination device as described in any embodiment of the present invention is integrated in the controller. The controller is used to obtain the electrochemical impedance spectrum of the target battery at different temperatures to determine whether the target battery has thermal runaway. The specific process can be referred to the above embodiment and will not be repeated here.

[0081] Optionally, the acquisition module includes a temperature sensor and an EIS impedance measurement unit, the temperature sensor is used to collect the real-time surface temperature of the target battery, and the EIS impedance measurement unit is used to collect real-time impedance data of the target battery.

[0082] Specifically, the temperature sensor is located on the surface of the target battery, which can collect the surface temperature of the target battery in real time and transmit the real-time collected temperature to the controller. The EIS impedance measurement unit collects the impedance data of the target battery in real time and transmits the real-time collected impedance data to the controller. When the temperature received by the controller exceeds the preset temperature threshold, the controller determines the temperature rise rate of the target battery based on the relationship function between impedance and temperature. When the temperature rise rate exceeds the preset temperature rise rate threshold, it is determined that the target battery is in thermal runaway.

[0083] The battery thermal runaway determination device and system provided in this embodiment and the battery thermal runaway determination method provided in any embodiment of the present invention belong to the same inventive concept and have corresponding beneficial effects. For technical details not detailed in this embodiment, please refer to the battery thermal runaway determination method provided in any embodiment of the present invention.

[0084] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for determining battery thermal runaway, characterized in that: include: Obtain the real-time surface temperature of the target battery; When the real-time surface temperature exceeds a preset temperature threshold, acquiring impedance data at a preset frequency point; Based on the relationship function between the impedance and the temperature at the preset frequency point, converting the impedance data at the preset frequency point into temperature data; Determining a temperature rise rate of the target battery according to the temperature data; When the temperature rise rate exceeds a preset temperature rise rate threshold, it is determined that the target battery is in thermal runaway.

2. The method for determining battery thermal runaway according to claim 1, characterized in that: Before obtaining the real-time surface temperature of the target battery, the method includes: Obtaining electrochemical impedance spectra of the target battery at different temperatures; The preset temperature threshold, the preset frequency point, and a relationship function between the impedance and the temperature at the preset frequency point are determined according to the electrochemical impedance spectrum.

3. The method for determining battery thermal runaway according to claim 2, characterized in that: The step of determining the preset temperature threshold, the preset frequency point, and the relationship function between the impedance and the temperature at the preset frequency point according to the electrochemical impedance spectrum includes: According to the electrochemical impedance spectrum, the lowest temperature value among the temperatures at which the impedance variation with temperature in the electrochemical impedance spectrum exceeds a preset variation threshold is used as the preset temperature threshold; The frequency point corresponding to the preset change threshold value at which the impedance change exceeds the preset change threshold value at each temperature value higher than the preset temperature threshold value is taken as the preset frequency point; A relationship function between the impedance at the preset frequency point and each temperature higher than the preset temperature threshold is established.

4. The method for determining battery thermal runaway according to claim 1, characterized in that: The step of converting the impedance data at the preset frequency point into temperature data based on the relationship function between the impedance at the preset frequency point and the temperature includes: According to the relationship function, the impedances corresponding to the preset frequency points at at least two different times are converted into corresponding temperatures to obtain the temperatures at at least two different times.

5. The method for determining battery thermal runaway according to claim 1, characterized in that: After determining that the target battery is in thermal runaway, the method includes: A warning prompt of thermal runaway of the target battery is issued.

6. The method for determining battery thermal runaway according to claim 1, characterized in that: The target battery is a lithium-ion battery.

7. A device for determining battery thermal runaway, characterized in that: include: A temperature acquisition module is used to obtain the real-time surface temperature of the target battery; An impedance acquisition module, used to acquire impedance data at a preset frequency point when the real-time surface temperature exceeds a preset temperature threshold; a temperature determination module, configured to convert the impedance data at the preset frequency point into temperature data based on a relationship function between the impedance and the temperature at the preset frequency point; A rate determination module, used to determine the temperature rise rate of the target battery according to the temperature data; The thermal runaway determination module is used to determine that the target battery is in thermal runaway when the temperature rise rate exceeds a preset temperature rise rate threshold.

8. The battery thermal runaway determination device according to claim 7, characterized in that: Also includes: An impedance spectrum acquisition module, used to acquire the electrochemical impedance spectrum of the target battery at different temperatures; The function determination module is used to determine the preset temperature threshold and the preset frequency point and the relationship function between the impedance and the temperature at the preset frequency point according to the electrochemical impedance spectrum.

9. A battery thermal runaway determination system, characterized in that: It comprises a collection module and a controller, wherein the collection module is communicatively connected to the controller, and the device as described in any one of claims 7-8 is integrated in the controller.

10. The battery thermal runaway determination system according to claim 9, characterized in that: The acquisition module includes a temperature sensor and an EIS impedance measurement unit. The temperature sensor is used to acquire the real-time surface temperature of the target battery, and the EIS impedance measurement unit is used to acquire the real-time impedance data of the target battery.

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