A method for quickly identifying micro-short circuit in lithium ion battery module

Abstract

The present application relates to the field of lithium ion battery module detection, and discloses a kind of lithium ion battery module in micro short circuit fast identification method, comprising: standard battery module is discharged to empty electricity state;Standard battery module is charged with first system, and the total voltage of standard battery module is obtained, and the charging potential of each single cell;Standard battery module is discharged with second system, and the total voltage of standard battery module is obtained, and the discharge potential of each single cell;According to the total voltage of standard battery module, the charging potential of each single cell, the total voltage of discharge and the discharge potential of each single cell, calculate reference voltage;The value of the voltage of the battery module to be measured is compared with the value of reference voltage to obtain the voltage difference value, and the preset threshold value is compared to determine whether the battery module to be measured appears internal micro short circuit signal.The present application can quantitatively analyze the degree of internal micro short circuit in battery module, and the test method is simple and accurate.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery module testing technology, specifically to a method for rapid identification of micro-short circuits within lithium-ion battery modules. Background Technology

[0002] Lithium-ion battery modules, as a new type of high-energy green battery module, are widely used in new energy vehicles and other fields, which puts forward higher requirements for the safety of lithium-ion battery modules; at the same time, the safety issues of lithium-ion battery modules are becoming increasingly prominent, attracting great attention from the industry.

[0003] Lithium-ion battery modules are highly susceptible to thermal runaway under abusive conditions, including thermal abuse, mechanical abuse, and electrical abuse. Internal short circuits are the most common form of electrical abuse and a significant contributing factor to self-initiated thermal runaway safety issues in ternary lithium-ion battery modules (depending on the severity of the internal short circuit, its resistance, and the relative magnitude of heat generation and dissipation). When the short-circuit resistance of the battery module is low, an internal short circuit can cause a sudden drop in voltage and a sharp increase in current and temperature, generating a large amount of heat in a short time, potentially triggering thermal runaway. When the short-circuit resistance is high, i.e., a small-scale internal short circuit, known as a micro-short circuit, it does not cause significant changes in voltage, current, and temperature in a short time and is difficult to detect, only manifesting as an excessively high self-discharge rate. However, if a micro-short circuit develops over a long period, the differences between battery modules gradually increase, and with the gradual accumulation of heat, safety problems may arise. Therefore, effective control of internal micro-short circuits in battery modules is essential.

[0004] Traditional short-circuit detection methods for power battery modules can only detect battery modules in non-operating states, which is time-consuming and cannot accurately detect battery modules in use, resulting in low detection accuracy. Furthermore, they cannot identify some potential micro-short-circuit signals. Moreover, while there is relatively more research on external short circuits in individual battery modules, there is relatively less research on short circuits within battery module groups, especially the real-time detection of micro-short-circuit faults within battery module groups. Existing battery module management technologies struggle to effectively identify micro-short-circuit faults.

[0005] Existing technology collects the terminal voltage Ui and output current I of each individual battery module in a secondary battery module group, calculates the equivalent internal resistance Zi of each individual battery module, and determines whether a micro-short circuit has occurred in the individual battery module by the difference ΔZi between Zi and a reference resistor. The reference resistor is the average of the equivalent internal resistances of all individual battery modules in the battery module group. If the number of individual battery modules connected in series in the battery module group is large, the existing micro-short circuit detection method involves a large computational load for real-time calculation of the equivalent internal resistance of each individual battery module, placing high demands on the hardware of the Battery Management System (BMS) and making implementation difficult. Furthermore, as the battery module group ages, the inconsistency between the individual battery modules increases. Using the ΔZi value to determine micro-short circuits can easily misinterpret inconsistencies as micro-short circuits, and can also misreport changes in internal resistance caused by faults such as contact resistance as micro-short circuits, resulting in a high probability of misjudgment and poor applicability. Therefore, real-time monitoring and detection of micro-short circuits is of great significance for the safe operation of power battery modules and the development of management systems.

[0006] Therefore, under current conditions, finding a method to accurately identify micro-short-circuit signals in battery modules is a critical issue. Based on this, it is necessary to develop an online detection method for identifying and warning of micro-short-circuit signals in lithium-ion battery modules. Summary of the Invention

[0007] This invention provides a rapid identification method for micro-short circuits within lithium-ion battery modules, which can quantitatively analyze the consumption of active lithium in the battery module. The testing method is simple and highly accurate.

[0008] Therefore, the present invention provides the following technical solution: A method for rapid identification of micro-short circuits within a lithium-ion battery module, the method comprising: Step 1: Discharge the standard battery module to a fully charged state; Step 2: Charge the standard battery module using the first system to obtain the total charging voltage of the standard battery module and the charging potential of each individual cell. Step 3: Discharge the standard battery module under the second system to obtain the total discharge voltage of the standard battery module and the discharge potential of each individual cell. Step 4: Calculate the reference voltage based on the total charging voltage of the standard battery module, the charging potential of each individual cell, the total discharging voltage of the standard battery module, and the discharging potential of each individual cell. Step 5: Compare the voltage value of the battery module under test with the reference voltage value to obtain the constant voltage difference value, and compare the constant voltage difference value with a preset threshold to determine whether the battery module under test has an internal micro short circuit signal.

[0009] Optionally, in step 2, when charging the standard battery module under the first system, the standard battery module is charged with a constant current T1 using a current I1, and the corresponding total voltage is denoted as V. mbc1 The potentials of individual cells 1 through n are denoted as: V m1bc1 ...V mnbc1 Let stand for 1-10 seconds, then use I 2c Discharge 1-10s, I 2c The total voltage corresponding to charging from 1 to 3.3 seconds is denoted as V'. mbc1 The total charging voltage of a standard battery module, and the potentials of individual cells 1 through n are respectively denoted as: V' m1bc1 ...V' mnbc1 That is, the charging potential of each individual cell; then repeat the above charging-resting steps n times, until the total voltage of the charging module or the individual cell voltage is greater than the charging cutoff voltage V1.

[0010] Optionally, in step 2, the cycling conditions of the battery in the standard battery module are: cycling temperature -20℃ to 55℃; current I1 range is I1≤0.5C, where C is a unit of current; cutoff voltage V1 range is V1≤4.6V; current I 2c The range is I 2c ≥2C.

[0011] Optionally, in step 3, when discharging the standard battery module under the second system, the standard battery module is discharged at a constant current of I2 for T2, and the corresponding total voltage is denoted as V. mbd1 The voltage of a single unit is V. m1bd1 ...V mnbd1 Let stand for 1-10 seconds, then use I 2d Charging for 1-10 seconds, I 2d The total voltage corresponding to 1-3.3 seconds of discharge is denoted as V'. mbd1 The total discharge voltage of a standard battery module, and the potentials of individual cells 1 through n are respectively denoted as: V' m1bd1 ...V' mnbd1 That is, the discharge potential of each individual cell; then the above discharge-resting steps can be repeated n' times, until the total voltage of the discharge module or the individual cell voltage is less than or equal to the discharge cutoff voltage V'1.

[0012] Optionally, in step 3, the cycling conditions of the battery in the standard battery module are: cycling temperature -20℃ to 55℃; current I2 range is I2≤0.5C, and cutoff voltage V'1 range is V'1≤2.0V; current I2d The range is I 2d ≥2C.

[0013] Optionally, in step 4, the battery pulse voltage data of individual cells in the standard battery module under certain conditions and the average value V' of the pulse voltage of all individual cells at different states of charge (SOC) / depth of discharge (DOD) are obtained. mpcn or V' mpdn This is the reference voltage.

[0014] Optionally, in step 5, the potential difference between the pulse of a single cell in the battery module under test and the reference voltage at the same charging and discharging time is calculated: △V' mnbcn =V' mnbcn - V' mpcn △V' mnbdn =V' mnbdn - V' mpdn In the formula, △V' mnbcn For the charging potential difference, V' mnbcn It is the charging voltage of the nth individual cell, V' mpcn It is the average value at different SOC times during charging; △V' mnbdn V' is the discharge potential difference. mnbdn It is the discharge voltage of the nth individual cell, V' mpdn It is the average value at different DOD times of discharge.

[0015] Optionally, in step 5, when comparing the constant voltage difference value with a preset threshold to determine whether the battery module under test has an internal micro-short circuit signal, the following situations are included: ① When DOD is 20%-50% or 70%-90%, 10mV≤△V' mnbdn When the voltage is <20mV, it is considered that a micro short circuit signal has been detected in the battery of the battery module under test; ②When DOD is between 20% and 50% or between 70% and 90%, △V' mnbcn >20mV or ΔV' mnbdn When the voltage is greater than 20mV, it is considered that a serious micro-short circuit has occurred in the battery of the battery module under test. ③△V' mnbdn ≤10mV and ΔV' mnbcn When the voltage is ≤10mV, the battery performance in the battery module under test is considered to be good. ④When the depth of charge / discharge (DOD) range exists outside of 20%-50% or 70%-90%, ΔV' is also present. mnbdnIf the voltage is greater than 10mV, it is considered that the individual cells in the battery module under test may have inconsistent voltages due to aging.

[0016] A rapid identification device for micro-short circuits within a lithium-ion battery module, the device comprising: The battery discharge unit discharges the standard battery module to a completely empty state; The battery charging unit charges the standard battery module using a first system to obtain the total charging voltage of the standard battery module and the charging potential of each individual cell. The battery discharge unit discharges the standard battery module under a second system to obtain the total discharge voltage of the standard battery module and the discharge potential of each individual cell. The reference voltage calculation unit calculates the reference voltage based on the total charging voltage of the standard battery module, the charging potential of each individual cell, the total discharging voltage of the standard battery module, and the discharging potential of each individual cell. The micro-short circuit determination unit compares the voltage value of the battery module under test with the reference voltage value to obtain a constant voltage difference value, and compares the constant voltage difference value with a preset threshold to determine whether the battery module under test has an internal micro-short circuit signal.

[0017] A computer-readable storage medium having a computer program stored thereon, the computer program being executed by a processor to perform the steps of the rapid identification method for micro short circuits within a lithium-ion battery module.

[0018] The rapid identification method for micro-short circuits within lithium-ion battery modules provided by this invention can quantitatively analyze the active lithium consumption in the battery module, providing significant guidance for the design and development of battery modules. On one hand, it allows for the design of the positive and negative electrode capacity ratio of the battery module; on the other hand, it enables pre-lithiation of the negative electrode based on actual failure mechanism analysis, further improving the cycle life of the battery module and preventing insufficient or excessive lithium replenishment of the negative electrode during battery module manufacturing, which could affect the subsequent use of the battery module. Furthermore, the testing method of this invention is simple and highly accurate. Compared with existing technologies, this invention has the following technical advantages: (1) The detection method of the present invention can accurately identify the micro short circuit signal in the individual cell of the battery module. It can not only identify the micro short circuit signal offline, but also identify the micro short circuit signal online, which improves the timeliness of the identification of the short circuit signal of the battery module. (2) The real-time battery module internal short circuit detection method described in this invention can further shorten the internal micro short circuit identification time, and compare the open circuit voltage of a single battery module with the reference battery module voltage, and judge whether the battery module has an abnormal voltage in real time by comparing the comparison value, which is accurate and efficient. (3) Another advantage of the present invention is that the method can be used in the battery module management system, reducing the false detection rate caused by the inconsistency of individual cells due to the aging of the battery module. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0020] Figure 1 This is a flowchart of a method for rapid identification of micro short circuits within a lithium-ion battery module according to a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a rapid micro-short circuit identification device in a lithium-ion battery module according to a specific embodiment of the present invention; Figure 3 The voltage difference diagrams during the charging process of Embodiments 1 and 2 of the present invention are shown. Figure 4 This is a voltage difference diagram of the charging process in Comparative Example 1 of the present invention. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0023] This invention addresses the problem of identifying micro-short-circuit signals in lithium-ion battery modules by providing an online identification method for determining whether a micro-short-circuit has occurred in the lithium-ion battery module. This method can effectively and accurately determine whether a micro-short circuit has occurred in the lithium-ion battery module. Figure 1 The diagram shown is a flowchart of a method for rapid identification of micro-short circuits within a lithium-ion battery module according to an embodiment of the present invention, including the following steps: Step 101: Discharge the standard battery module to a depleted state.

[0024] Step 102: Charge the standard battery module for a certain period of time according to a certain system to obtain the total charging voltage of the standard battery module and the charging potential of each individual cell.

[0025] The standard battery module is charged with a constant current I1 to T1, and the corresponding total voltage is denoted as V. mbc1 The potentials of individual cells 1 through n are denoted as: V m1bc1 ...V mnbc1 Let it stand for 1-10 seconds, then I 2c Discharge 1-10s, I 2c The total voltage corresponding to charging from 1 to 3.3 seconds is denoted as V'. mbc1 The potentials of individual cells 1 through n are denoted as: V' m1bc1 ...V' mnbc1 Then the charging-resting steps can be repeated n times until the total voltage of the charging module or the voltage of a single cell is greater than the charging cutoff voltage V1.

[0026] The battery cycling conditions are: cycling temperature -20℃ to 55℃; current I1 range I1≤0.5C; cutoff voltage V1 range V1≤4.6V. Current I 2c The range is I 2c ≥2C.

[0027] Step 103: Discharge the standard battery module for a certain period of time according to a certain regime to obtain the total discharge voltage of the standard battery module and the discharge potential of each individual cell.

[0028] The standard battery module is discharged at a constant current of I2 for T2, and the corresponding total voltage is denoted as V. mbd1 The voltage of a single unit is V. m1bd1 ...V mnbd1 Let it stand for 1-10 seconds, then I 2d Charging for 1-10 seconds, I 2d The total voltage corresponding to 1-3.3 seconds of discharge is denoted as V'. mbd1 The potentials of individual cells 1 through n are denoted as: V' m1bd1 ...V' mnbd1 Then the above discharge-resting steps can be repeated n' times, until the total voltage of the discharge module or the voltage of a single cell is less than or equal to the discharge cutoff voltage.

[0029] The battery cycling conditions are: cycling temperature -20℃ to 55℃; current I2 range I2≤0.5C; cutoff voltage V'1 range V'1≤2.0V. Current I 2d The range is I 2d ≥2C.

[0030] Step 104: Calculate the reference voltage based on the total charging voltage of the standard battery module, the charging potential of each individual cell, the total discharging voltage of the standard battery module, and the discharging potential of each individual cell.

[0031] Obtain the pulse voltage data of individual cells in a standard battery module under certain conditions, as well as the average pulse voltage V' of all individual cells at different states of charge (SOC) / depths of discharge (DOD). mpcn or V' mpdn The reference voltage is calculated by adding the values ​​of 1 to n batteries and then dividing by n to obtain the average value.

[0032] Step 105: Compare the voltage value of the battery module under test with the reference voltage value, and compare the constant voltage difference value with a preset threshold to determine whether the battery module under test has an internal micro-short circuit signal. The positive electrode of the battery module under test is a lithium-rich manganese-based positive electrode material or a ternary positive electrode material, and the negative electrode active material is a carbon-based negative electrode material or a graphite negative electrode material.

[0033] Calculate the potential difference between the pulse voltage and the reference voltage of a single cell in a series module at the same charge / discharge time: △V' mnbcn =V' mnbcn - V' mpcn △V' mnbdn =V' mnbdn - V' mpdn In the formula, △V' mnbcn For the charging potential difference, V' mnbcn It is the charging voltage of the nth individual cell, V' mpcn It is the average value at different SOC times during charging; △V' mnbdn V' is the discharge potential difference. mnbdn It is the discharge voltage of the nth individual cell, V' mpdn It is the average value at different DOD times of discharge.

[0034] Compare with threshold voltage: ① When DOD is 20%-50% or 70%-90%, 10mV≤△V' mnbdn A voltage of <20mV indicates that a micro short circuit signal has been detected in the battery. ② When the percentage is 20%-50% or 70%-90%, △V' mnbcn >20mV or ΔV' mnbdn A voltage greater than 20mV indicates a severe micro-short circuit in the battery.

[0035] ③△V' mnbdn ≤10mV and ΔV'mnbcn A voltage ≤10mV indicates good battery performance. ④ When ΔV' exists in other depth of charge / discharge ranges besides 20%-50% or 70%-90%, mnbdn If the voltage is >10mV, it is believed that the voltage of individual cells in the module may be inconsistent due to aging or other reasons.

[0036] Example 1 Step 1: Cyclic Test: The 20Ah 1P5S module with ternary cathode material and graphite anode material is charged at a constant current of 0.33C to a total voltage of 21V or a single cell voltage of 4.2V. Then, it is charged at a constant voltage of 4.2V to a current of 1 / 20C. After resting for 30 minutes, the battery is discharged at a constant current of 0.33C to a single cell voltage of 2.8V. The battery is subjected to 3 cycles of charge and discharge test.

[0037] Step 2: Charge the standard battery module at 0.1C to 3.6V, let it rest for 10s, then discharge at 2C for 10s and charge at 2C for 3.3s. Record the total voltage corresponding to this period as V'. mbc1 The potentials of individual cells 1 through n are denoted as: V' m1bc1 ...V' mnbc1 Repeat the above steps to charge to 3.6V, 3.65V, 3.675V, 3.725V, 3.75V, 3.8V, and 4.2V respectively. Step 3: Then, discharge the standard battery module at 0.1C to 3.8V, let it rest for 10 seconds, then charge at 0.1C for 10 seconds, discharge at 0.1C for 3.3 seconds, and repeat the above steps to charge to 3.75V, 3.725V, 3.675V, 3.65V, and 3.6V respectively; record the voltage of the battery module after each pulse, as shown in Table 1. Figure 3 As shown in the figure.

[0038] Step 4: Obtain the pulse voltage data of individual cells in the series module under certain conditions, and the average pulse voltage V' of all individual cells at different SOC / DOD. mpcn or V' mpdn The reference voltage; Step 5: Subtract the voltage at the same time in Step 3 and Step 2 from the reference voltage and compare it with the threshold voltage. It is found that when the voltage of the battery module under test 1 is greater than 3.6V and less than or equal to 3.8V, the voltage difference is greater than 20mV, indicating that the battery module under test has a serious internal micro short circuit.

[0039] Example 2 Step 1: Cyclic Test: The 20Ah 1P5S module with ternary cathode material and graphite anode material is charged at a constant current of 0.33C to a total voltage of 21V or a single cell voltage of 4.2V. Then, it is charged at a constant voltage of 4.2V to a current of 1 / 20C. After resting for 30 minutes, the battery is discharged at a constant current of 0.33C to a single cell voltage of 2.8V. The battery is subjected to 3 cycles of charge and discharge test.

[0040] Step 2: Charge the standard battery module at 0.1C to 3.6V, let it rest for 10s, then discharge at 2C for 10s and charge at 2C for 3.3s. Record the total voltage corresponding to this period as V'. mbc1 The potentials of individual cells 1 through n are denoted as: V' m1bc1 ...V' mnbc1 Repeat the above steps to charge to 3.6V, 3.65V, 3.675V, 3.725V, 3.75V, 3.8V, and 4.2V respectively. Step 3: Then, discharge the standard battery module at 0.1C to 3.8V, let it rest for 10 seconds, then charge at 0.1C for 10 seconds, discharge at 0.1C for 3.3 seconds, and repeat the above steps to charge to 3.75V, 3.725V, 3.675V, 3.65V, and 3.6V respectively; record the voltage of the battery module after each pulse, as shown in Table 1. Figure 3 As shown.

[0041] Step 4: Obtain the pulse voltage data of individual cells in the series module under certain conditions, and the average pulse voltage V' of all individual cells at different SOC / DOD. mpcn or V' mpdn The reference voltage; Step 5: Subtract the individual cell voltages from Step 3 and Step 2 from the reference voltages of the same depth of charge / discharge (SOC) or depth of discharge (DOD), and compare them with the threshold voltages. If the test battery module ΔV'cn≤10mV and ΔV'dn≤10mV, then the test battery module 2 is considered to have no micro-short circuit signal.

[0042] Table 1. Voltage differences between single cell 1 and reference discharge at different stages after resting in Examples 1 and 2.

[0043] Comparative Example 1 Step 1: Capacity test: The 20Ah battery module with lithium manganese oxide as the positive electrode material and graphite as the negative electrode material is charged at a constant current of 0.33C to a voltage of 4.2V, and then charged at a constant voltage of 4.2V to a current of 1 / 20C. After standing for 30 minutes, the battery module is discharged at a constant current of 0.33C to a voltage of 2.8V. The battery module is subjected to 3 cycles of charge and discharge test.

[0044] Step 2: Charge the standard battery module at 0.1C for 60 minutes, then let it stand for 3 hours. Repeat the above steps until the battery module voltage reaches 4.2V, then let it stand for another 3 hours. Then discharge the standard battery module at 0.1C for 10 minutes, then let it stand for 3 hours. Repeat the above steps until the battery module discharge voltage reaches 2.8V, then let it stand for another 3 hours. Record the voltage of the battery module after standing at different stages, as shown in Table 1.

[0045] Step 3: Charge the battery module 1 under test at 0.1C for 60 minutes, then let it stand for 3 hours. Repeat the above steps 6 times. Record the voltage of the battery module after standing at different stages, as shown in Table 2.

[0046] Table 2. Voltage differences between Comparative Example 1 single cell 5 and reference cell after different stages of discharge and resting.

[0047] Step 4: Subtract the individual cell voltages from Steps 3 and 2 from the reference voltage of the same depth of charge / discharge (SOC) or DOD, and compare this with the threshold voltage. It was found that when the voltage of the tested battery module 1 is greater than 3.6V and less than or equal to 3.8V, the voltage difference is greater than 20mV, indicating a severe internal micro-short circuit in the tested battery module 1. Based on this result, a severe micro-short circuit signal was found in the tested battery module 1. However, testing the short-circuit internal resistance of individual cell 5 in this module revealed that the internal resistance of individual cell 5 was normal, indicating that no short circuit occurred under these conditions. The results are as follows. Figure 4 As shown.

[0048] Accordingly, embodiments of the present invention also provide a rapid identification device for micro-short circuits within a lithium-ion battery module, such as... Figure 2 The diagram shown is a structural schematic of the device. This micro-short circuit rapid identification device within a lithium-ion battery module includes the following modules: The battery discharge unit 201 discharges the standard battery module to a completely empty state. The battery charging unit 202 charges the standard battery module under a first regime to obtain the total charging voltage of the standard battery module and the charging potential of each individual cell. The battery discharge unit 203 discharges the standard battery module under a second system to obtain the total discharge voltage of the standard battery module and the discharge potential of each individual cell. The reference voltage calculation unit 204 calculates the reference voltage based on the total charging voltage of the standard battery module, the charging potential of each individual cell, the total discharging voltage of the standard battery module, and the discharging potential of each individual cell. The micro-short circuit determination unit 205 compares the voltage value of the battery module under test with the value of the reference voltage to obtain a constant voltage difference value, and compares the constant voltage difference value with a preset threshold to determine whether the battery module under test has an internal micro-short circuit signal.

[0049] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0050] The present invention also provides a storage medium, which is a computer-readable storage medium storing a computer program thereon, the computer program being executable when it runs. Figure 1 The method shown may include some or all of the steps. The storage medium may include read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, etc. The storage medium may also include non-volatile memory or non-transitory memory, etc.

[0051] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer program are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data provider to another website, computer, server, or data provider via wired or wireless means.

[0052] The embodiments of the present invention have been described in detail above. Specific implementation methods have been used to illustrate the present invention. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and systems of the present invention, and are merely some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention, and the content of this specification should not be construed as a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for rapid identification of micro-short circuits within a lithium-ion battery module, characterized in that, The method includes: Step 1: Discharge the standard battery module to a fully charged state; Step 2: Charge the standard battery module using the first system to obtain the total charging voltage of the standard battery module and the charging potential of each individual cell. Step 3: Discharge the standard battery module under the second system to obtain the total discharge voltage of the standard battery module and the discharge potential of each individual cell. Step 4: Calculate the reference voltage based on the total charging voltage of the standard battery module, the charging potential of each individual cell, the total discharging voltage of the standard battery module, and the discharging potential of each individual cell. Step 5: Compare the voltage value of the battery module under test with the reference voltage value to obtain the constant voltage difference value, and compare the constant voltage difference value with a preset threshold to determine whether the battery module under test has an internal micro short circuit signal.

2. The method for rapid identification of micro-short circuits within a lithium-ion battery module according to claim 1, characterized in that, In step 2, when the standard battery module is charged under the first system, the standard battery module is charged with a constant current T1 using a current I1, and the corresponding total voltage is denoted as V. mbc1 The potentials of individual cells 1 through n are denoted as: V m1bc1 ...V mnbc1 Let stand for 1-10 seconds, then use I 2c Discharge 1-10s, I 2c The total voltage corresponding to charging from 1 to 3.3 seconds is denoted as V'. mbc1 The total charging voltage of a standard battery module, and the potentials of individual cells 1 through n are respectively denoted as: V' m1bc1 ...V' mnbc1 That is, the charging potential of each individual cell; then repeat the above charging-resting steps n times, until the total voltage of the charging module or the individual cell voltage is greater than the charging cutoff voltage V1.

3. The method for rapid identification of micro-short circuits within a lithium-ion battery module according to claim 2, characterized in that, In step 2, the cycling conditions for the batteries in the standard battery module are: cycling temperature -20℃ to 55℃; current I1 range is I1≤0.5C, where C is a unit of current; cutoff voltage V1 range is V1≤4.6V; current I 2c The range is I 2c ≥2C.

4. The method for rapid identification of micro-short circuits within a lithium-ion battery module according to claim 1, characterized in that, In step 3, when discharging the standard battery module under the second system, the standard battery module is discharged at a constant current of I2 for T2, and the corresponding total voltage is recorded as V. mbd1 The voltage of a single unit is V. m1bd1 ...V mnbd1 Let stand for 1-10 seconds, then use I 2d Charging for 1-10 seconds, I 2d The total voltage corresponding to 1-3.3 seconds of discharge is denoted as V'. mbd1 The total discharge voltage of a standard battery module, and the potentials of individual cells 1 through n are respectively denoted as: V' m1bd1 ...V' mnbd1 That is, the discharge potential of each individual cell; then repeat the above discharge-resting steps n' times, until the total voltage of the discharge module or the individual cell voltage is less than or equal to the discharge cutoff voltage V'1.

5. The method for rapid identification of micro-short circuits within a lithium-ion battery module according to claim 4, characterized in that, In step 3, the cycling conditions for the batteries in the standard battery module are: cycling temperature -20℃ to 55℃; current I2 range is I2≤0.5C; cutoff voltage V'1 range is V'1≤2.0V; current I 2d The range is I 2d ≥2C.

6. The method for rapid identification of micro-short circuits within a lithium-ion battery module according to claim 1, characterized in that, In step 4, obtain the battery pulse voltage data of individual cells in the standard battery module under certain conditions, as well as the average pulse voltage V' of all individual cells at different states of charge (SOC) / depths of discharge (DOD). mpcn or V' mpdn This is the reference voltage.

7. The method for rapid identification of micro-short circuits within a lithium-ion battery module according to claim 1, characterized in that, In step 5, calculate the potential difference between the pulse of a single cell in the battery module under test and the reference voltage at the same charging and discharging time: △V' mnbcn =V' mnbcn - V' mpcn △V' mnbdn =V' mnbdn - V' mpdn In the formula, △V' mnbcn For the charging potential difference, V' mnbcn It is the charging voltage of the nth individual cell, V' mpcn It is the average value at different SOC times during charging; △V' mnbdn V' is the discharge potential difference. mnbdn It is the discharge voltage of the nth individual cell, V' mpdn It is the average value at different DOD times of discharge.

8. The method for rapid identification of micro-short circuits within a lithium-ion battery module according to claim 7, characterized in that, In step 5, when comparing the constant voltage difference value with a preset threshold to determine whether the battery module under test has an internal micro-short circuit signal, the following situations are included: ① When DOD is 20%-50% or 70%-90%, 10mV≤△V' mnbdn When the voltage is <20mV, it is considered that a micro short circuit signal has been detected in the battery of the battery module under test; ②When DOD is between 20% and 50% or between 70% and 90%, △V' mnbcn >20mV or ΔV' mnbdn When the voltage is greater than 20mV, it is considered that a serious micro-short circuit has occurred in the battery of the battery module under test. ③△V' mnbdn ≤10mV and ΔV' mnbcn When the voltage is ≤10mV, the battery performance in the battery module under test is considered to be good. ④When the depth of charge / discharge (DOD) range exists outside of 20%-50% or 70%-90%, ΔV' is also present. mnbdn If the voltage is greater than 10mV, it is considered that the voltage of the individual cells in the battery module under test may be inconsistent due to aging.

9. A rapid identification device for micro-short circuits within a lithium-ion battery module, characterized in that, The device includes: The battery discharge unit discharges the standard battery module to a completely empty state; The battery charging unit charges the standard battery module using a first system to obtain the total charging voltage of the standard battery module and the charging potential of each individual cell. The battery discharge unit discharges the standard battery module under a second system to obtain the total discharge voltage of the standard battery module and the discharge potential of each individual cell. The reference voltage calculation unit calculates the reference voltage based on the total charging voltage of the standard battery module, the charging potential of each individual cell, the total discharging voltage of the standard battery module, and the discharging potential of each individual cell. The micro-short circuit determination unit compares the voltage value of the battery module under test with the reference voltage value to obtain a constant voltage difference value, and compares the constant voltage difference value with a preset threshold to determine whether the battery module under test has an internal micro-short circuit signal.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is run by the processor, it performs the steps of the rapid identification method for micro short circuits in a lithium-ion battery module as described in any one of claims 1 to 8.

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