Self-discharge type judgment method and device of battery, electronic equipment and storage medium

Abstract

The invention particularly relates to a battery self-discharge type judgment method and device, electronic equipment and a storage medium, and the method comprises the steps: enabling a battery cell with abnormal self-discharge to stand for a first preset time and a second preset time in sequence at a first preset temperature, obtaining a first open-circuit voltage and a second open-circuit voltage, and calculating a first total self-discharge rate, then the battery cell with the abnormal self-discharge is subjected to standing at a second preset temperature for a third preset time and a fourth preset time respectively, a third open-circuit voltage and a fourth open-circuit voltage are obtained respectively, the low-temperature voltage drop of the battery cell with the abnormal self-discharge is calculated according to the third open-circuit voltage and the fourth open-circuit voltage, and if the low-temperature voltage drop is larger than or equal to the preset voltage drop, the battery cell with the abnormal self-discharge is started. If yes, it is judged that physical self-discharge exists in the battery cell with the abnormal self-discharge, the battery cell with the abnormal self-discharge stands at the first preset temperature for a fifth preset time, a fifth open-circuit voltage is obtained, then a second total self-discharge rate is calculated, and the self-discharge type of the battery cell with the abnormal self-discharge is judged based on the first total self-discharge rate and the second total self-discharge rate.

Description

Technical Field

[0001] The present application relates to the technical field of battery self-discharge detection, and in particular to a method, device, electronic device and storage medium for determining the self-discharge type of a battery. Background Art

[0002] Lithium-ion batteries are widely used in the digital and power energy industries due to their high energy density, long cycle life and no memory effect. However, when lithium-ion batteries are left in an open circuit, they will experience spontaneous capacity loss, which is called self-discharge. Excessive self-discharge will cause the battery storage voltage to drop too quickly, affecting the consistency of the battery voltage, and further affecting the life and capacity of the lithium battery pack. Therefore, in the production process of batteries, self-discharge screening is extremely important. However, self-discharge screening will inevitably cause some defective rates. The level of defective rates is related to the economic benefits of the enterprise. Reducing the self-discharge defective rate is a long-term pursuit of the enterprise.

[0003] Self-discharge can be divided into two categories, namely physical self-discharge and chemical self-discharge. Among them, chemical self-discharge is inherent in the battery cell and is inevitable. If the chemical self-discharge value is abnormally large, it is necessary to analyze the specific reasons, which may be excessive internal moisture, incomplete depolarization, etc.; physical self-discharge is mainly caused by internal micro-short circuits, mainly including dust particles in the process, diaphragm damage, ear warping and contact with the shell, abnormal diaphragm material, etc., so the self-discharge failure rate of the battery cell needs to be continuously reduced and optimized.

[0004] However, related technologies usually involve a large number of disassemblies of abnormal self-discharge cells to analyze their causes. The workload is often large and the verification results cannot be guaranteed, resulting in a high rate of cell self-discharge defects, which urgently needs to be resolved. Summary of the invention

[0005] The present application provides a method, device, electronic device and storage medium for determining the self-discharge type of a battery, so as to solve the problem that the self-discharge detection method in the related art is often unable to accurately distinguish between physical self-discharge and chemical self-discharge types, and a large number of disassembly of abnormal self-discharge cells are required to analyze the causes. The workload is often large and the verification results cannot be guaranteed, which leads to problems such as high self-discharge defect rate of the cells. Based on the self-discharge type determination method of the battery in the embodiment of the present application, the self-discharge type of the cell can be determined, and targeted analysis and improvement can be performed to reduce the self-discharge defect rate of the cell.

[0006] A first aspect of the present application provides a method for determining a self-discharge type of a battery, comprising the following steps:

[0007] Determine a self-discharge abnormal cell of a to-be-determined type, place the self-discharge abnormal cell of the to-be-determined type at a first preset temperature for a first preset time and a second preset time, respectively, and measure a first open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after being placed at the first preset time, and a second open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after being placed at the second preset time, and calculate a first total self-discharge rate of the self-discharge abnormal cell of the to-be-determined type according to the first open circuit voltage and the second open circuit voltage;

[0008] Setting a normal self-discharge cell, allowing the abnormal self-discharge cell of the type to be determined and the normal self-discharge cell to stand for a third preset time at a second preset temperature after standing for two times at the first preset temperature, until the normal self-discharge cell meets a preset stability condition, recording a third open circuit voltage of the abnormal self-discharge cell of the type to be determined, allowing the abnormal self-discharge cell of the type to be determined to stand for a fourth preset time at the second preset temperature after standing for the third preset time, measuring a fourth open circuit voltage of the abnormal self-discharge cell of the type to be determined after standing for the fourth preset time, calculating a low-temperature voltage drop of the abnormal self-discharge cell of the type to be determined based on the third open circuit voltage and the fourth open circuit voltage, and judging whether the abnormal self-discharge cell of the type to be determined has physical self-discharge based on the low-temperature voltage drop;

[0009] If the self-discharge abnormal battery cell of the to-be-determined type has physical self-discharge, the self-discharge abnormal battery cell of the to-be-determined type is left to stand for a fifth preset time at the first preset temperature, and the fifth open circuit voltage of the self-discharge abnormal battery cell of the to-be-determined type after standing for the fifth preset time is measured, and the second total self-discharge rate of the self-discharge abnormal battery cell of the to-be-determined type is calculated based on the second open circuit voltage and the fifth open circuit voltage, and the physical self-discharge ratio and chemical self-discharge ratio of the self-discharge abnormal battery cell of the to-be-determined type are obtained based on the first total self-discharge rate and the second total self-discharge rate, so as to determine the self-discharge type of the self-discharge abnormal battery cell of the to-be-determined type according to the physical self-discharge ratio and the chemical self-discharge ratio.

[0010] According to an embodiment of the present application, judging whether the self-discharge abnormal battery cell of the type to be determined has physical self-discharge according to the low-temperature voltage drop includes:

[0011] Determining whether the low temperature pressure drop is greater than or equal to a preset pressure drop;

[0012] If the low-temperature voltage drop is greater than or equal to the preset voltage drop, it is determined that the self-discharge abnormal battery cell of the to-be-determined type has physical self-discharge; otherwise, it is determined that the self-discharge abnormal battery cell of the to-be-determined type has no physical self-discharge.

[0013] According to an embodiment of the present application, the low-temperature voltage drop of the self-discharge abnormal battery cell of the type to be determined is the difference between the third open-circuit voltage and the fourth open-circuit voltage.

[0014] According to one embodiment of the present application, the first total self-discharge rate is:

[0015] K1 = (first open circuit voltage - second open circuit voltage) / room temperature standing time;

[0016] The second total self-discharge rate is:

[0017] K2 = (second open circuit voltage - fifth open circuit voltage) / low temperature standing time.

[0018] According to one embodiment of the present application, the first preset temperature is 25±2°C, and the second preset temperature is less than or equal to -20°C.

[0019] According to the method for determining the self-discharge type of a battery in an embodiment of the present application, a battery cell with abnormal self-discharge is allowed to stand for a first preset time and a second preset time at a first preset temperature, respectively, to obtain a first open circuit voltage and a second open circuit voltage, respectively, and a first total self-discharge rate is calculated. Then, the battery cell with abnormal self-discharge is allowed to stand for a third preset time and a fourth preset time at the second preset temperature, respectively, to obtain a third open circuit voltage and a fourth open circuit voltage, respectively. A low-temperature voltage drop of the battery cell with abnormal self-discharge is calculated based on the third open circuit voltage and the fourth open circuit voltage. If the low-temperature voltage drop is greater than or equal to the preset voltage drop, it is determined that physical self-discharge exists in the battery cell with abnormal self-discharge. The battery cell with abnormal self-discharge is allowed to stand for a fifth preset time at the first preset temperature, to obtain a fifth open circuit voltage, and then a second total self-discharge rate is calculated. Based on the first total self-discharge rate and the second total self-discharge rate, a physical self-discharge ratio and a chemical self-discharge ratio of the battery cell with abnormal self-discharge are obtained, and then the self-discharge type of the battery cell with abnormal self-discharge is determined. Thus, the problem that the self-discharge detection methods in related technologies are often unable to accurately distinguish between physical self-discharge and chemical self-discharge types, and that a large number of cells with abnormal self-discharge need to be disassembled to analyze the causes, which is often a large workload and cannot guarantee the verification results, thus leading to problems such as a high rate of cell self-discharge failure. The self-discharge type of lithium-ion batteries is determined through three stages of temperature control and static testing, and the ratio of physical self-discharge to chemical self-discharge is accurately distinguished, so that the cell self-discharge type can be determined, and targeted analysis and improvement can be carried out to reduce the cell self-discharge failure rate.

[0020] A second aspect of the present application provides a device for determining a self-discharge type of a battery, comprising:

[0021] a first calculation module, for determining a self-discharge abnormal cell of a to-be-determined type, placing the self-discharge abnormal cell of the to-be-determined type at a first preset temperature for a first preset time and a second preset time, respectively, and measuring a first open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after being placed at the first preset time, and a second open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after being placed at the second preset time, and calculating a first total self-discharge rate of the self-discharge abnormal cell of the to-be-determined type according to the first open circuit voltage and the second open circuit voltage;

[0022] a second calculation module, for setting a self-discharge normal cell, allowing the self-discharge abnormal cell of the to-be-determined type and the self-discharge normal cell to stand for a third preset time at the second preset temperature after standing for two times at the first preset temperature, until the self-discharge normal cell meets a preset stability condition, recording a third open circuit voltage of the self-discharge abnormal cell of the to-be-determined type, allowing the self-discharge abnormal cell of the to-be-determined type to stand for a fourth preset time at the second preset temperature after standing for the third preset time, measuring a fourth open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after standing for the fourth preset time, calculating a low-temperature voltage drop of the self-discharge abnormal cell of the to-be-determined type according to the third open circuit voltage and the fourth open circuit voltage, and judging whether the self-discharge abnormal cell of the to-be-determined type has physical self-discharge according to the low-temperature voltage drop;

[0023] A determination module is used for, if the self-discharge abnormal battery cell of the type to be determined has physical self-discharge, then allowing the self-discharge abnormal battery cell of the type to be determined to stand for a fifth preset time at the first preset temperature, measuring the fifth open circuit voltage of the self-discharge abnormal battery cell of the type to be determined after standing for the fifth preset time, calculating the second total self-discharge rate of the self-discharge abnormal battery cell of the type to be determined according to the second open circuit voltage and the fifth open circuit voltage, and obtaining the physical self-discharge ratio and chemical self-discharge ratio of the self-discharge abnormal battery cell of the type to be determined based on the first total self-discharge rate and the second total self-discharge rate, so as to determine the self-discharge type of the self-discharge abnormal battery cell of the type to be determined according to the physical self-discharge ratio and the chemical self-discharge ratio.

[0024] According to an embodiment of the present application, the second calculation module is specifically used to:

[0025] Determining whether the low temperature pressure drop is greater than or equal to a preset pressure drop;

[0026] If the low-temperature voltage drop is greater than or equal to the preset voltage drop, it is determined that the self-discharge abnormal battery cell of the to-be-determined type has physical self-discharge; otherwise, it is determined that the self-discharge abnormal battery cell of the to-be-determined type has no physical self-discharge.

[0027] According to an embodiment of the present application, the low-temperature voltage drop of the self-discharge abnormal battery cell of the type to be determined is the difference between the third open-circuit voltage and the fourth open-circuit voltage.

[0028] According to one embodiment of the present application, the first total self-discharge rate is:

[0029] K1 = (first open circuit voltage - second open circuit voltage) / room temperature standing time;

[0030] The second total self-discharge rate is:

[0031] K2 = (second open circuit voltage - fifth open circuit voltage) / low temperature standing time.

[0032] According to one embodiment of the present application, the first preset temperature is 25±2°C, and the second preset temperature is less than or equal to -20°C.

[0033] According to the self-discharge type determination device of the battery in the embodiment of the present application, the abnormal self-discharge cell is allowed to stand for a first preset time and a second preset time at a first preset temperature, respectively, to obtain a first open circuit voltage and a second open circuit voltage, respectively, and a first total self-discharge rate is calculated. Then, the abnormal self-discharge cell is allowed to stand for a third preset time and a fourth preset time at the second preset temperature, respectively, to obtain a third open circuit voltage and a fourth open circuit voltage, respectively. The low-temperature voltage drop of the abnormal self-discharge cell is calculated based on the third open circuit voltage and the fourth open circuit voltage. If the low-temperature voltage drop is greater than or equal to the preset voltage drop, it is determined that the abnormal self-discharge cell has physical self-discharge. The abnormal self-discharge cell is allowed to stand for a fifth preset time at the first preset temperature to obtain a fifth open circuit voltage, and then the second total self-discharge rate is calculated. Based on the first total self-discharge rate and the second total self-discharge rate, the physical self-discharge ratio and the chemical self-discharge ratio of the abnormal self-discharge cell are obtained, and then the self-discharge type of the abnormal self-discharge cell is determined. Thus, the problem that the self-discharge detection methods in related technologies are often unable to accurately distinguish between physical self-discharge and chemical self-discharge types, and that a large number of cells with abnormal self-discharge need to be disassembled to analyze the causes, which is often a large workload and cannot guarantee the verification results, thus leading to problems such as a high rate of cell self-discharge failure. The self-discharge type of lithium-ion batteries is determined through three stages of temperature control and static testing, and the ratio of physical self-discharge to chemical self-discharge is accurately distinguished, so that the cell self-discharge type can be determined, and targeted analysis and improvement can be carried out to reduce the cell self-discharge failure rate.

[0034] A third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for determining the self-discharge type of a battery as described in the above embodiment.

[0035] A fourth aspect of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the method for determining the self-discharge type of a battery as described in the above embodiment.

[0036] A fifth aspect of the present application provides a computer program product, including a computer program, which is executed to implement the method for determining the self-discharge type of a battery as described in the above embodiment.

[0037] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0039] Figure 1 A flowchart of a method for determining a self-discharge type of a battery provided according to an embodiment of the present application;

[0040] Figure 2 A flow chart of a method for identifying the self-discharge type of a lithium-ion battery according to an embodiment of the present application;

[0041] Figure 3 is a block diagram of an exemplary device for determining a self-discharge type of a battery according to an embodiment of the present application;

[0042] Figure 4 Schematic diagram of the structure of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0043] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0044] The following describes the method, device, electronic device and storage medium for determining the self-discharge type of a battery according to an embodiment of the present application with reference to the accompanying drawings. The self-discharge detection method of the related art mentioned in the above background technology is often unable to accurately distinguish between physical self-discharge and chemical self-discharge types, and requires a large number of disassembly of abnormal self-discharge cells to analyze the causes. The workload is often large and the verification results cannot be guaranteed, which leads to the problem of high self-discharge defect rate of the cells. The present application provides a method for determining the self-discharge type of a battery. In this method, the abnormal self-discharge cells are left to stand for a first preset time and a second preset time at a first preset temperature, respectively, to obtain a first open circuit voltage and a second open circuit voltage, respectively, and to calculate a first total self-discharge rate. Then, the abnormal self-discharge cells are placed at a first preset temperature for a first preset time and a second preset time. The battery is allowed to stand for a third preset time and a fourth preset time at a set temperature to obtain a third open circuit voltage and a fourth open circuit voltage respectively, and the low-temperature voltage drop of the battery cell with abnormal self-discharge is calculated according to the third open circuit voltage and the fourth open circuit voltage. If the low-temperature voltage drop is greater than or equal to the preset voltage drop, it is determined that physical self-discharge exists in the battery cell with abnormal self-discharge. The battery cell with abnormal self-discharge is allowed to stand for a fifth preset time at the first preset temperature to obtain a fifth open circuit voltage, and then the second total self-discharge rate is calculated. Based on the first total self-discharge rate and the second total self-discharge rate, the physical self-discharge ratio and the chemical self-discharge ratio of the battery cell with abnormal self-discharge are obtained, and then the self-discharge type of the battery cell with abnormal self-discharge is determined. Thus, the problem that the self-discharge detection methods in related technologies are often unable to accurately distinguish between physical self-discharge and chemical self-discharge types, and that a large number of cells with abnormal self-discharge need to be disassembled to analyze the causes, which is often a large workload and cannot guarantee the verification results, thus leading to problems such as a high rate of cell self-discharge failure. The self-discharge type of lithium-ion batteries is determined through three stages of temperature control and static testing, and the ratio of physical self-discharge to chemical self-discharge is accurately distinguished, so that the cell self-discharge type can be determined, and targeted analysis and improvement can be carried out to reduce the cell self-discharge failure rate.

[0045] Before introducing the embodiments of the present application, the relevant principles of lithium-ion battery self-discharge and the problems existing in the related technologies are first introduced. When the lithium-ion battery is in an open circuit idle state, the phenomenon of spontaneous capacity loss is called the self-discharge of the lithium-ion battery, which can also be called the charge retention capacity of the lithium-ion battery. The K value is a quantitative description of the rate of battery voltage drop. The calculation method is the difference in the open circuit voltage of the two tests divided by the time interval between the two voltage tests. If the K value is too large, it means that the battery storage voltage drops faster, and the voltage consistency of the battery with large self-discharge will become increasingly worse over time. According to the barrel principle, if the self-discharging abnormal battery and the normal battery form a module, the inconsistency of the self-discharge of each battery will lead to a reduction in the life of the lithium battery pack and a rapid decay of capacity, thereby affecting the use of the battery.

[0046] Therefore, in the process of battery cell production, self-discharge screening is very important. Through self-discharge screening, cells with large self-discharge can be eliminated to improve the self-discharge consistency and long-term performance of the battery cells. However, self-discharge screening will inevitably cause some defective rates, which will affect the economic benefits and long-term development pursuits of the technology industry. Therefore, it is necessary to identify the self-discharge type of battery cells to analyze the root cause of self-discharge according to the self-discharge type, so as to improve the self-discharge defect ratio from the source.

[0047] Among them, self-discharge can be divided into two categories according to the category, namely physical self-discharge and chemical self-discharge. Among them, chemical self-discharge is inherent in the battery cell and is inevitable. If the chemical self-discharge value is abnormally large, it is necessary to analyze the specific reasons, which may be excessive internal moisture, incomplete depolarization, etc.; physical self-discharge is mainly caused by internal micro-short circuits, mainly including dust particles in the process, diaphragm damage, pole ears lifting and contacting the shell, diaphragm material abnormalities, etc., so the battery cell self-discharge failure rate needs to be continuously reduced and optimized. Therefore, based on the above-mentioned existing problems, the embodiment of the present application needs to accurately distinguish the type of self-discharge anomaly, so that the self-discharge failure rate of the battery cell based on the self-discharge anomaly type can be continuously optimized, and it can provide a scientific basis for battery production and quality control.

[0048] Specifically, Figure 1 A schematic flow chart of a method for determining the self-discharge type of a battery provided in an embodiment of the present application.

[0049] like Figure 1 As shown, the method for determining the self-discharge type of the battery includes the following steps:

[0050] In step S101, a self-discharge abnormal cell of the to-be-determined type is determined, and the self-discharge abnormal cell of the to-be-determined type is left standing at a first preset temperature for a first preset time and a second preset time respectively, and a first open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after being left standing for the first preset time and a second open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after being left standing for the second preset time are measured, and a first total self-discharge rate of the self-discharge abnormal cell of the to-be-determined type is calculated based on the first open circuit voltage and the second open circuit voltage.

[0051] Among them, the first preset temperature, the first preset time and the second preset time can all be set by those skilled in the art according to actual test requirements and are not specifically limited here.

[0052] Specifically, the embodiment of the present application is mainly divided into three stages to determine the self-discharge type of the battery, namely, the first stage - the total self-discharge K of the static test at room temperature 1The second stage - low temperature to determine the self-discharge type, the third stage - normal temperature OCV (Open Circuit Voltage) recovery to obtain the ratio of physical self-discharge and chemical self-discharge.

[0053] Specifically, if Figure 2 As shown, in the first stage, first, the self-discharge abnormal cell of the to-be-determined type of the battery at a first preset temperature (e.g., 25±2°C) is determined, the self-discharge abnormal cell of the to-be-determined type is first allowed to stand for a first preset time (e.g., 6-12h) at the first preset temperature, and the first open circuit voltage OCV of the self-discharge abnormal cell of the to-be-determined type after standing for the first preset time is calculated. 1 ; Secondly, the self-discharge abnormal cell of the type to be determined is allowed to stand for a second preset time (e.g., 5-10 days) at the first preset temperature, and the second open circuit voltage OCV of the self-discharge abnormal cell of the type to be determined after the second preset time is calculated. 2 ; Finally, according to the first open circuit voltage OCV 1 and the second open circuit voltage OCV 2 Calculate the first total self-discharge rate K of the self-discharge abnormal battery cell of the type to be determined after two static periods 1 , which can be expressed as:

[0054] K 1 =(OCV 1 -OCV 2 ) / t 1 ;

[0055] Among them, t 1 is the standing time at room temperature (unit: day (d)).

[0056] That is to say, in the first stage - the total self-discharge K of the room temperature static test 1 First, select the self-discharge abnormal cell of the type to be determined and place it at room temperature of 25±2℃ for 6-12h. After 6-12h of standing, calculate the first open circuit voltage OCV of the self-discharge abnormal cell of the type to be determined. 1 ; Then, continue to let the self-discharge abnormal cell of the type to be determined, which has been left to stand for 6-12 hours, stand at 25±2°C for 5-10 days, and calculate the second open circuit voltage OCV of the self-discharge abnormal cell of the type to be determined at this time 2 ; Finally, according to the first open circuit voltage OCV 1 and the second open circuit voltage OCV 2 Calculate the first total self-discharge rate K of the self-discharge abnormal battery cell of the type to be determined at 25±2℃ after two static periods 1 =(OCV 1 -OCV 2) / t 1 .

[0057] For example, in the embodiment of the present application, a self-discharge abnormal cell of the type to be determined is placed at 25±2°C for 6 hours, and the first open circuit voltage OCV of the self-discharge abnormal cell of the type to be determined is tested at this time. 1 3226.3mv, then continue to stand at 25±2℃ for 7 days, at this time test the second open circuit voltage OCV of the self-discharge abnormal cell of the type to be determined 2 is 3221.1mv. Finally, the first total self-discharge rate K at 25±2℃ is obtained. 1 =(3226.3-3221.1) / 7=0.74mv / d.

[0058] In step S102, a self-discharge normal battery cell is set, and the self-discharge abnormal battery cell of the to-be-determined type and the self-discharge normal battery cell, which have been left standing twice at a first preset temperature, are left standing at a second preset temperature for a third preset time until the self-discharge normal battery cell meets a preset stability condition, and the third open circuit voltage of the self-discharge abnormal battery cell of the to-be-determined type is recorded, and the self-discharge abnormal battery cell of the to-be-determined type, which has been left standing for the third preset time, is left standing at the second preset temperature for a fourth preset time, and the fourth open circuit voltage of the self-discharge abnormal battery cell of the to-be-determined type after being left standing for the fourth preset time is measured, and the low-temperature voltage drop of the self-discharge abnormal battery cell of the to-be-determined type is calculated based on the third open circuit voltage and the fourth open circuit voltage, and it is determined whether the self-discharge abnormal battery cell of the to-be-determined type has physical self-discharge based on the low-temperature voltage drop.

[0059] According to an embodiment of the present application, judging whether there is physical self-discharge in a self-discharge abnormal battery cell of the type to be judged based on the low-temperature voltage drop includes: judging whether the low-temperature voltage drop is greater than or equal to a preset voltage drop; if the low-temperature voltage drop is greater than or equal to the preset voltage drop, judging that there is physical self-discharge in the self-discharge abnormal battery cell of the type to be judged, otherwise, judging that there is no physical self-discharge in the self-discharge abnormal battery cell of the type to be judged.

[0060] According to an embodiment of the present application, the low-temperature voltage drop of the self-discharge abnormal battery cell of the type to be determined is the difference between the third open-circuit voltage and the fourth open-circuit voltage.

[0061] Among them, the second preset temperature, the third preset time, the fourth preset time, the preset stability condition and the preset pressure drop can all be set by technical personnel in this field according to actual test requirements and are not specifically limited here.

[0062] Specifically, Figure 2As shown, in the second stage, first, add self-discharge normal cells as the base group, and place the self-discharge abnormal cells and self-discharge normal cells of the to-be-determined type after being left to stand for two times at the first preset temperature for a third preset time at the second preset temperature (for example, ≤-20°C), that is, place the self-discharge abnormal cells of the to-be-determined type after being left to stand in a constant temperature box, and the temperature of the incubator is set to ≤-20°C; secondly, monitor the OCV of the self-discharge abnormal cells and self-discharge normal cells of the to-be-determined type during the whole process. Since the OCV of the cells increases continuously with decreasing temperature, when the open circuit voltage of the self-discharge normal cells meets the preset stability condition, that is, after the open circuit voltage of the self-discharge normal cells rises to the highest point and stabilizes, it indicates that the internal temperature of the self-discharge abnormal cells of the to-be-determined type has dropped to the preset temperature at this time, and the stabilization time is used as the starting time of the standing, and the third open circuit voltage OCV of the self-discharge abnormal cells of the to-be-determined type is recorded at this time. 3 ; Again, the self-discharge abnormal battery cell of the type to be determined after being left standing for the third preset time is further left standing for a fourth preset time (e.g., 5-20 days) at the second preset temperature, and the fourth open circuit voltage OCV of the self-discharge abnormal battery cell of the type to be determined after being left standing for the fourth preset time is measured 4 , because when the temperature is ≤-20℃, the ionic conductivity of the electrolyte in the battery cell is very low, and the chemical self-discharge is basically reduced to 0. At this time, the self-discharge can be considered to be all physical self-discharge. Therefore, according to the third open circuit voltage OCV 3 and the fourth open circuit voltage OCV 4 Calculate the low temperature voltage drop of the self-discharge abnormal cell of the type to be determined △OCV=OCV 3 -OCV 4 ; Finally, excluding the test error, if the low-temperature voltage drop is greater than or equal to the preset voltage drop, that is, the low-temperature voltage drop △OCV≥1mv, it is determined that the self-discharge abnormal battery cell of the type to be determined has physical self-discharge; if the low-temperature voltage drop △OCV<1mv, it is determined that the self-discharge abnormal battery cell of the type to be determined does not have physical self-discharge.

[0063] That is to say, Figure 2 As shown, the self-discharge abnormal cells of the type to be determined after the first stage is completed are placed in a constant temperature thermostat, and the self-discharge normal cells are added as the base group, wherein the temperature of the thermostat is set to ≤-20°C, and the OCV of all cells is monitored. Since the OCV of the cell increases with the decrease in temperature, the third open circuit voltage OCV of the self-discharge abnormal cell of the type to be determined corresponding to the OCV of the self-discharge normal cell of the base group meets the preset stability condition is recorded. 3 , let the abnormal self-discharge cell stand for 5-20 days, and record the fourth open circuit voltage OCV of the abnormal self-discharge cell of the type to be determined at low temperature. 4 , according to the third open circuit voltage OCV 3 and the fourth open circuit voltage OCV4 Calculate the low temperature pressure drop △OCV=OCV 3 -OCV 4 Therefore, when the low-temperature voltage drop △OCV≥1mv, it is determined that physical self-discharge exists, and when the low-temperature voltage drop △OCV<1mv, it is determined that there is basically no physical self-discharge.

[0064] For example, in the embodiment of the present application, the self-discharge abnormal battery cell after the first stage is completed is placed in a constant temperature box with a temperature of -20°C, the OCV of all battery cells is monitored during the process, and the third open circuit voltage OCV of the self-discharge abnormal battery cell corresponding to the self-discharge normal battery cell of the base group is recorded when the OCV of the self-discharge normal battery cell meets the preset stability condition. 3 The fourth open circuit voltage OCV of the self-discharge abnormal cell of the type to be determined at this time is 3231.1mv. The self-discharge abnormal cell of the type to be determined at this time is left to stand for 15 days, and the fourth open circuit voltage OCV of the self-discharge abnormal cell of the type to be determined at this time at low temperature is recorded. 4 It is 3209.4mv, so we can calculate the low-temperature voltage drop △OCV=3231.1-3209.4=21.7mv, indicating the existence of physical self-discharge.

[0065] In step S103, if the self-discharge abnormal battery cell of the to-be-determined type has physical self-discharge, the self-discharge abnormal battery cell of the to-be-determined type is left to stand at a first preset temperature for a fifth preset time, and the fifth open circuit voltage of the self-discharge abnormal battery cell of the to-be-determined type after standing for the fifth preset time is measured, and the second total self-discharge rate of the self-discharge abnormal battery cell of the to-be-determined type is calculated based on the second open circuit voltage and the fifth open circuit voltage, and the physical self-discharge ratio and chemical self-discharge ratio of the self-discharge abnormal battery cell of the to-be-determined type are obtained based on the first total self-discharge rate and the second total self-discharge rate, so as to determine the self-discharge type of the self-discharge abnormal battery cell of the to-be-determined type according to the physical self-discharge ratio and the chemical self-discharge ratio.

[0066] The fifth preset time can be set by those skilled in the art according to actual test requirements and is not specifically limited here.

[0067] Specifically, based on the self-discharge abnormal cell of the type to be determined after standing at the second preset temperature, the self-discharge abnormal cell of the type to be determined is stood at the first preset temperature for a fifth preset time (e.g., 1-2d), and the fifth open circuit voltage OCV of the self-discharge abnormal cell of the type to be determined after standing for the fifth preset time is measured. 5 , calculate the second total self-discharge rate K of the self-discharge abnormal cell of the type to be determined according to the second open circuit voltage and the fifth open circuit voltage 2 , which can be expressed as:

[0068] K 2 =(OCV 2 -OCV 5 ) / t2 ;

[0069] Among them, t 2 is the low temperature standing time (unit: day (d)).

[0070] Furthermore, the physical self-discharge ratio and chemical self-discharge ratio of the self-discharge abnormal battery cell of the type to be determined are obtained based on the first total self-discharge ratio and the second total self-discharge ratio, so as to determine the self-discharge type of the self-discharge abnormal battery cell of the type to be determined according to the physical self-discharge ratio and the chemical self-discharge ratio.

[0071] That is to say, Figure 2 As shown, after the self-discharge abnormal cell of the type to be determined is left at the second preset temperature, the self-discharge abnormal cell of the type to be determined is left at 25±2°C for 1-2 days to obtain the fifth open circuit voltage OCV of the self-discharge abnormal cell of the type to be determined 5 , according to the second open circuit voltage OCV 2 and the fifth open circuit voltage OCV 5 Calculate the second total self-discharge rate K of the self-discharge abnormal cell of the type to be determined 2 =(OCV 2 -OCV 5 ) / t 2 , then, based on the first total self-discharge rate K 1 and the second total self-discharge rate K 2 Get the physical self-discharge ratio and chemical self-discharge ratio of the self-discharge abnormal cell of the type to be determined, where the physical self-discharge ratio = K 2 / K 1 *100%, chemical self-discharge ratio = 100% - K 2 / K 1 *100%, thereby determining the self-discharge type of the self-discharge abnormal battery cell of the type to be determined according to the physical self-discharge ratio and the chemical self-discharge ratio.

[0072] For example, after the second stage of low-temperature standing, the embodiment of the present application stands for 1-2 days at room temperature 25±2°C for the self-discharge abnormal battery cell of the type to be determined, and tests the fifth open circuit voltage OCV of the self-discharge abnormal battery cell of the type to be determined at this time. 5 is 3211.6mv, according to the second open circuit voltage OCV 2 and the fifth open circuit voltage OCV 5 Calculate the second total self-discharge rate K of the self-discharge abnormal cell of the type to be determined 2 =(3221.1-3211.6) / 15=0.63mv / d, thus based on the first total self-discharge rate K 1 and the second total self-discharge rate K 2Get the physical self-discharge ratio of the self-discharge abnormal cell of the type to be determined = K 2 / K 1 *100%=0.63 / 0.74=85.1%, and chemical self-discharge ratio=100%-85.1%=14.9%, indicating that the self-discharge abnormal cell to be determined is mainly physical self-discharge, and the internal short circuit of the cell needs to be checked.

[0073] Therefore, based on the above specific description, the embodiments of the present application can achieve the following beneficial effects:

[0074] (1) Confirm the self-discharge type through low-temperature self-discharge test;

[0075] (2) Through normal temperature recovery, the physical self-discharge value is quantified and the physical self-discharge ratio is determined;

[0076] (3) Identifying the self-discharge type of lithium-ion batteries through three different stages helps to improve the efficiency of battery production and quality control, reduce the defective rate, and thus improve the economic benefits of the enterprise.

[0077] According to the method for determining the self-discharge type of a battery in an embodiment of the present application, a battery cell with abnormal self-discharge is allowed to stand for a first preset time and a second preset time at a first preset temperature, respectively, to obtain a first open circuit voltage and a second open circuit voltage, respectively, and a first total self-discharge rate is calculated. Then, the battery cell with abnormal self-discharge is allowed to stand for a third preset time and a fourth preset time at the second preset temperature, respectively, to obtain a third open circuit voltage and a fourth open circuit voltage, respectively. A low-temperature voltage drop of the battery cell with abnormal self-discharge is calculated based on the third open circuit voltage and the fourth open circuit voltage. If the low-temperature voltage drop is greater than or equal to the preset voltage drop, it is determined that physical self-discharge exists in the battery cell with abnormal self-discharge. The battery cell with abnormal self-discharge is allowed to stand for a fifth preset time at the first preset temperature, to obtain a fifth open circuit voltage, and then a second total self-discharge rate is calculated. Based on the first total self-discharge rate and the second total self-discharge rate, a physical self-discharge ratio and a chemical self-discharge ratio of the battery cell with abnormal self-discharge are obtained, and then the self-discharge type of the battery cell with abnormal self-discharge is determined. Thus, the problem that the self-discharge detection methods in related technologies are often unable to accurately distinguish between physical self-discharge and chemical self-discharge types, and that a large number of cells with abnormal self-discharge need to be disassembled to analyze the causes, which is often a large workload and cannot guarantee the verification results, thus leading to problems such as a high rate of cell self-discharge failure. The self-discharge type of lithium-ion batteries is determined through three stages of temperature control and static testing, and the ratio of physical self-discharge to chemical self-discharge is accurately distinguished, so that the cell self-discharge type can be determined, and targeted analysis and improvement can be carried out to reduce the cell self-discharge failure rate.

[0078] Next, a device for determining the self-discharge type of a battery according to an embodiment of the present application will be described with reference to the accompanying drawings.

[0079] Figure 3 It is a block diagram of a device for determining a self-discharge type of a battery according to an embodiment of the present application.

[0080] like Figure 3 As shown, the battery self-discharge type determination device 10 includes: a first calculation module 100 , a second calculation module 200 and a determination module 300 .

[0081] The first calculation module 100 is used to determine the self-discharge abnormal cell of the type to be determined, and to place the self-discharge abnormal cell of the type to be determined at a first preset temperature for a first preset time and a second preset time, respectively, and to measure the first open circuit voltage of the self-discharge abnormal cell of the type to be determined after being placed for the first preset time, and the second open circuit voltage of the self-discharge abnormal cell of the type to be determined after being placed for the second preset time, and to calculate the first total self-discharge rate of the self-discharge abnormal cell of the type to be determined according to the first open circuit voltage and the second open circuit voltage;

[0082] The second calculation module 200 is used to set a self-discharge normal cell, and to place the self-discharge abnormal cell and the self-discharge normal cell of the type to be determined after being left standing for two times at the first preset temperature for a third preset time at the second preset temperature until the self-discharge normal cell meets a preset stability condition, and to record the third open circuit voltage of the self-discharge abnormal cell of the type to be determined, and to place the self-discharge abnormal cell of the type to be determined after being left standing for the third preset time at the second preset temperature for a fourth preset time, and to measure the fourth open circuit voltage of the self-discharge abnormal cell of the type to be determined after being left standing for the fourth preset time, and to calculate the low-temperature voltage drop of the self-discharge abnormal cell of the type to be determined according to the third open circuit voltage and the fourth open circuit voltage, and to judge whether the self-discharge abnormal cell of the type to be determined has physical self-discharge according to the low-temperature voltage drop;

[0083] The determination module 300 is used for allowing the self-discharge abnormal battery cell to stand for a fifth preset time at a first preset temperature, measuring the fifth open circuit voltage of the self-discharge abnormal battery cell of the type to be determined after standing for the fifth preset time, calculating the second total self-discharge rate of the self-discharge abnormal battery cell of the type to be determined based on the second open circuit voltage and the fifth open circuit voltage, and obtaining the physical self-discharge ratio and chemical self-discharge ratio of the self-discharge abnormal battery cell of the type to be determined based on the first total self-discharge ratio and the second total self-discharge ratio, so as to determine the self-discharge type of the self-discharge abnormal battery cell of the type to be determined according to the physical self-discharge ratio and the chemical self-discharge ratio.

[0084] According to one embodiment of the present application, the second calculation module 200 is specifically configured to:

[0085] Determine whether the low temperature pressure drop is greater than or equal to the preset pressure drop;

[0086] If the low-temperature voltage drop is greater than or equal to the preset voltage drop, it is determined that the self-discharge abnormal battery cell of the type to be determined has physical self-discharge; otherwise, it is determined that the self-discharge abnormal battery cell of the type to be determined has no physical self-discharge.

[0087] According to an embodiment of the present application, the low-temperature voltage drop of the self-discharge abnormal battery cell of the type to be determined is the difference between the third open-circuit voltage and the fourth open-circuit voltage.

[0088] According to one embodiment of the present application, the first total self-discharge rate is:

[0089] K1 = (first open circuit voltage - second open circuit voltage) / room temperature standing time;

[0090] The second total self-discharge rate is:

[0091] K2 = (second open circuit voltage - fifth open circuit voltage) / low temperature standing time.

[0092] According to an embodiment of the present application, the first preset temperature is 25±2°C, and the second preset temperature is less than or equal to 20°C.

[0093] According to the self-discharge type determination device of the battery in the embodiment of the present application, the abnormal self-discharge cell is allowed to stand for a first preset time and a second preset time at a first preset temperature, respectively, to obtain a first open circuit voltage and a second open circuit voltage, respectively, and a first total self-discharge rate is calculated. Then, the abnormal self-discharge cell is allowed to stand for a third preset time and a fourth preset time at the second preset temperature, respectively, to obtain a third open circuit voltage and a fourth open circuit voltage, respectively. The low-temperature voltage drop of the abnormal self-discharge cell is calculated based on the third open circuit voltage and the fourth open circuit voltage. If the low-temperature voltage drop is greater than or equal to the preset voltage drop, it is determined that the abnormal self-discharge cell has physical self-discharge. The abnormal self-discharge cell is allowed to stand for a fifth preset time at the first preset temperature to obtain a fifth open circuit voltage, and then the second total self-discharge rate is calculated. Based on the first total self-discharge rate and the second total self-discharge rate, the physical self-discharge ratio and the chemical self-discharge ratio of the abnormal self-discharge cell are obtained, and then the self-discharge type of the abnormal self-discharge cell is determined. Thus, the problem that the self-discharge detection methods in related technologies are often unable to accurately distinguish between physical self-discharge and chemical self-discharge types, and that a large number of cells with abnormal self-discharge need to be disassembled to analyze the causes, which is often a large workload and cannot guarantee the verification results, thus leading to problems such as a high rate of cell self-discharge failure. The self-discharge type of lithium-ion batteries is determined through three stages of temperature control and static testing, and the ratio of physical self-discharge to chemical self-discharge is accurately distinguished, so that the cell self-discharge type can be determined, and targeted analysis and improvement can be carried out to reduce the cell self-discharge failure rate.

[0094] Figure 4 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0095] Memory 401 , processor 402 , and a computer program stored in the memory 401 and executable on the processor 402 .

[0096] When the processor 402 executes the program, the method for determining the self-discharge type of the battery provided in the above embodiment is implemented.

[0097] Furthermore, the electronic device further comprises:

[0098] The communication interface 403 is used for communication between the memory 401 and the processor 402 .

[0099] The memory 401 is used to store computer programs that can be executed on the processor 402 .

[0100] The memory 401 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0101] If the memory 401, the processor 402 and the communication interface 403 are implemented independently, the communication interface 403, the memory 401 and the processor 402 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 4 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0102] Optionally, in a specific implementation, if the memory 401, the processor 402 and the communication interface 403 are integrated on a chip, the memory 401, the processor 402 and the communication interface 403 can communicate with each other through an internal interface.

[0103] The processor 402 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0104] This embodiment further provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the above-mentioned method for determining the self-discharge type of a battery is implemented.

[0105] This embodiment further provides a computer program product, including a computer program, which is executed to implement the method for determining the self-discharge type of a battery in the above embodiment.

[0106] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0107] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0108] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0109] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or N wirings (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or otherwise processing in a suitable manner if necessary, and then stored in a computer memory.

[0110] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0111] A person skilled in the art may understand that all or part of the steps in the above-mentioned embodiment method may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0112] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0113] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for determining the self-discharge type of a battery, characterized in that: The following steps are involved: Determine a self-discharge abnormal cell of a to-be-determined type, place the self-discharge abnormal cell of the to-be-determined type at a first preset temperature for a first preset time and a second preset time, respectively, and measure a first open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after being placed at the first preset time, and a second open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after being placed at the second preset time, and calculate a first total self-discharge rate of the self-discharge abnormal cell of the to-be-determined type according to the first open circuit voltage and the second open circuit voltage; Setting a normal self-discharge cell, allowing the abnormal self-discharge cell of the type to be determined and the normal self-discharge cell to stand for a third preset time at a second preset temperature after standing for two times at the first preset temperature, until the normal self-discharge cell meets a preset stability condition, recording a third open circuit voltage of the abnormal self-discharge cell of the type to be determined, allowing the abnormal self-discharge cell of the type to be determined to stand for a fourth preset time at the second preset temperature after standing for the third preset time, measuring a fourth open circuit voltage of the abnormal self-discharge cell of the type to be determined after standing for the fourth preset time, calculating a low-temperature voltage drop of the abnormal self-discharge cell of the type to be determined based on the third open circuit voltage and the fourth open circuit voltage, and judging whether the abnormal self-discharge cell of the type to be determined has physical self-discharge based on the low-temperature voltage drop; If the self-discharge abnormal battery cell of the to-be-determined type has physical self-discharge, the self-discharge abnormal battery cell of the to-be-determined type is left to stand for a fifth preset time at the first preset temperature, and the fifth open circuit voltage of the self-discharge abnormal battery cell of the to-be-determined type after standing for the fifth preset time is measured, and the second total self-discharge rate of the self-discharge abnormal battery cell of the to-be-determined type is calculated based on the second open circuit voltage and the fifth open circuit voltage, and the physical self-discharge ratio and chemical self-discharge ratio of the self-discharge abnormal battery cell of the to-be-determined type are obtained based on the first total self-discharge rate and the second total self-discharge rate, so as to determine the self-discharge type of the self-discharge abnormal battery cell of the to-be-determined type according to the physical self-discharge ratio and the chemical self-discharge ratio.

2. The method according to claim 1, characterized in that The step of judging whether the self-discharging abnormal battery cell of the type to be determined has physical self-discharging according to the low-temperature voltage drop comprises: Determining whether the low temperature pressure drop is greater than or equal to a preset pressure drop; If the low-temperature voltage drop is greater than or equal to the preset voltage drop, it is determined that the self-discharge abnormal battery cell of the to-be-determined type has physical self-discharge; otherwise, it is determined that the self-discharge abnormal battery cell of the to-be-determined type has no physical self-discharge.

3. The method according to claim 1, characterized in that The low-temperature voltage drop of the self-discharge abnormal battery cell of the type to be determined is the difference between the third open-circuit voltage and the fourth open-circuit voltage.

4. The method according to claim 1, characterized in that The first total self-discharge rate is: K1 = (first open circuit voltage - second open circuit voltage) / room temperature standing time; The second total self-discharge rate is: K2 = (second open circuit voltage - fifth open circuit voltage) / low temperature standing time.

5. The method according to claim 1, characterized in that The first preset temperature is 25±2°C, and the second preset temperature is less than or equal to -20°C.

6. A device for determining the self-discharge type of a battery, characterized in that: include: a first calculation module, for determining a self-discharge abnormal cell of a to-be-determined type, placing the self-discharge abnormal cell of the to-be-determined type at a first preset temperature for a first preset time and a second preset time, respectively, and measuring a first open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after being placed at the first preset time, and a second open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after being placed at the second preset time, and calculating a first total self-discharge rate of the self-discharge abnormal cell of the to-be-determined type according to the first open circuit voltage and the second open circuit voltage; a second calculation module, for setting a self-discharge normal cell, allowing the self-discharge abnormal cell of the to-be-determined type and the self-discharge normal cell to stand for a third preset time at the second preset temperature after standing for two times at the first preset temperature, until the self-discharge normal cell meets a preset stability condition, recording a third open circuit voltage of the self-discharge abnormal cell of the to-be-determined type, allowing the self-discharge abnormal cell of the to-be-determined type to stand for a fourth preset time at the second preset temperature after standing for the third preset time, measuring a fourth open circuit voltage of the self-discharge abnormal cell of the to-be-determined type after standing for the fourth preset time, calculating a low-temperature voltage drop of the self-discharge abnormal cell of the to-be-determined type according to the third open circuit voltage and the fourth open circuit voltage, and judging whether the self-discharge abnormal cell of the to-be-determined type has physical self-discharge according to the low-temperature voltage drop; A determination module is used for, if the self-discharge abnormal battery cell of the type to be determined has physical self-discharge, then allowing the self-discharge abnormal battery cell of the type to be determined to stand for a fifth preset time at the first preset temperature, measuring the fifth open circuit voltage of the self-discharge abnormal battery cell of the type to be determined after standing for the fifth preset time, calculating the second total self-discharge rate of the self-discharge abnormal battery cell of the type to be determined according to the second open circuit voltage and the fifth open circuit voltage, and obtaining the physical self-discharge ratio and chemical self-discharge ratio of the self-discharge abnormal battery cell of the type to be determined based on the first total self-discharge rate and the second total self-discharge rate, so as to determine the self-discharge type of the self-discharge abnormal battery cell of the type to be determined according to the physical self-discharge ratio and the chemical self-discharge ratio.

7. The device according to claim 6, characterized in that The second calculation module is specifically used for: Determining whether the low temperature pressure drop is greater than or equal to a preset pressure drop; If the low-temperature voltage drop is greater than or equal to the preset voltage drop, it is determined that the self-discharge abnormal battery cell of the to-be-determined type has physical self-discharge; otherwise, it is determined that the self-discharge abnormal battery cell of the to-be-determined type has no physical self-discharge.

8. The device according to claim 6, characterized in that The low-temperature voltage drop of the self-discharge abnormal battery cell of the type to be determined is the difference between the third open-circuit voltage and the fourth open-circuit voltage.

9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for determining the self-discharge type of a battery as described in any one of claims 1 to 5.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the method for determining the self-discharge type of a battery as described in any one of claims 1 to 5.

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