Battery state evaluation method, battery state evaluation device and computer storage medium

Abstract

The invention discloses a battery state evaluation method, a battery state evaluation device and a computer storage medium. The method comprises the following steps: determining a first battery voltage; standing the battery at a first preset temperature for a first preset duration, and obtaining a second battery voltage; under the condition that the battery meets the first preset condition, allowing the battery to stand for a second preset duration at a second preset temperature and stand for a third preset duration at the first preset temperature in sequence, and acquiring a third battery voltage; under the condition that the battery meets a second preset condition, standing the battery at the first preset temperature for a fourth preset duration, and obtaining a fourth battery voltage; and determining a K value according to the fourth battery voltage and the third battery voltage so as to evaluate the self-discharge state of the battery. According to the method, primary screening is carried out on the battery twice, the situation of screening leakage of the battery cell with a large K value is reduced, meanwhile, battery cell polarization of the battery is fully eliminated based on normal-temperature standing and high-temperature standing, K value calculation is more accurate, and the battery state evaluation effect is improved.

Description

Technical Field

[0001] The present application relates to the technical field of battery status evaluation, and in particular to a battery status evaluation method, a computer-readable storage medium, and a battery status evaluation device. 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. The phenomenon of spontaneous capacity loss when lithium-ion batteries are in an open circuit state is called self-discharge of lithium-ion batteries. If batteries with abnormal self-discharge are combined with normal batteries to form a module, the inconsistency of self-discharge of each battery will lead to a reduction in the life of the lithium battery module and a rapid decay of the capacity of the battery module, thus affecting the use of the battery module.

[0003] To solve the above technical problems, the related technology uses K value to evaluate and screen the self-discharge status of the battery. Specifically, the voltages OCV1 and OCV2 are obtained in the order of charging the battery → storing for a period of time T1 → testing voltage OCV1 → storing for a period of time T2 → testing voltage OCV2. The K value of the battery is calculated by the ratio of the difference between OCV1 and OCV2 and the difference between the two storage times. The larger the K value, the faster the battery storage voltage drops, that is, there is a self-discharge anomaly. However, the voltage fluctuation obtained by this technical solution is large and distorted, resulting in a large error in the calculated K value, which reduces the effectiveness of the battery status assessment. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the first purpose of the present application is to propose a battery status assessment method, which performs two preliminary screenings on the battery based on the battery voltage obtained by standing at room temperature and standing at high temperature, reduces the occurrence of missed screening of cells with large K values, and can fully eliminate the polarization of the battery cells based on standing at room temperature and standing at high temperature, so that the obtained battery voltage is more accurate, the K value calculation is more accurate, and the battery status assessment effect is greatly improved.

[0005] A second object of the present application is to provide a computer-readable storage medium.

[0006] The third objective of the present application is to provide a battery status assessment device.

[0007] To achieve the above-mentioned purpose, the first embodiment of the present application proposes a battery state evaluation method, which includes: charging the battery to a target SOC (States of Charge) and obtaining a first battery voltage of the battery; allowing the battery to stand for a first preset time at a first preset temperature, and obtaining a second battery voltage of the battery after standing; when it is determined that the battery meets the first preset condition based on the first battery voltage and the second battery voltage, allowing the battery to stand for a second preset time at the second preset temperature and for a third preset time at the first preset temperature in sequence, and obtaining a third battery voltage of the battery after standing, wherein the second preset temperature is greater than the first preset temperature; when it is determined that the battery meets the second preset condition based on the second battery voltage and the third battery voltage, allowing the battery to stand for a fourth preset time at the first preset temperature, and obtaining a fourth battery voltage of the battery after standing; determining the K value of the battery based on the fourth battery voltage, the third battery voltage and the fourth preset time, so as to evaluate the self-discharge state of the battery based on the K value of the battery.

[0008] According to the battery state evaluation method of the embodiment of the present application, the battery is first charged to a target SOC and a first battery voltage of the battery is obtained. The battery is then allowed to stand for a first preset time at a first preset temperature and a second battery voltage of the battery after standing is obtained. When it is determined that the battery meets the first preset condition based on the first battery voltage and the second battery voltage, the battery is allowed to stand for a second preset time at the second preset temperature and for a third preset time at the first preset temperature in sequence, and a third battery voltage of the battery after standing is obtained, wherein the second preset temperature is greater than the first preset temperature. When it is determined that the battery meets the second preset condition based on the second battery voltage and the third battery voltage, the battery is allowed to stand for a fourth preset time at the first preset temperature and a fourth battery voltage of the battery after standing is obtained. The K value of the battery is determined based on the fourth battery voltage, the third battery voltage and the fourth preset time, so as to evaluate the self-discharge state of the battery based on the K value of the battery. Therefore, the method performs two preliminary screenings on the battery based on the battery voltages obtained by standing at room temperature and at high temperature, thereby reducing the occurrence of missed screening of cells with large K values. At the same time, the polarization of the battery cells can be fully eliminated based on standing at room temperature and at high temperature, so that the obtained battery voltage is more precise and the K value calculation is more accurate, which greatly improves the battery status assessment effect.

[0009] In addition, the battery status evaluation method according to the above embodiment of the present application may also have the following additional technical features:

[0010] According to an embodiment of the present application, after obtaining the battery voltage, the battery status evaluation method includes: obtaining the current battery temperature of the battery; and correcting the battery voltage based on the current battery temperature and a first preset temperature.

[0011] According to one embodiment of the present application, the battery voltage is corrected based on the current battery temperature and the first preset temperature, including: obtaining the difference between the current battery temperature and the first preset temperature to obtain the first temperature; obtaining the product of the first temperature and the preset temperature compensation coefficient to obtain the compensation voltage; obtaining the sum of the battery voltage and the compensation voltage to obtain the corrected battery voltage.

[0012] According to one embodiment of the present application, determining that a battery satisfies a first preset condition based on a first battery voltage and a second battery voltage includes: obtaining a difference between the first battery voltage and the second battery voltage to obtain a first voltage drop, and determining that the battery satisfies the first preset condition when the first voltage drop is less than or equal to the first preset voltage drop.

[0013] According to one embodiment of the present application, determining whether a battery satisfies a second preset condition based on a second battery voltage and a third battery voltage includes: obtaining a voltage difference between the second battery voltage and the third battery voltage to obtain a second voltage drop, and determining that the battery satisfies the second preset condition when the second voltage drop is less than or equal to the second preset voltage drop.

[0014] According to one embodiment of the present application, the K value of the battery is determined according to the fourth battery voltage, the third battery voltage and the fourth preset time, including: obtaining the voltage difference between the fourth battery voltage and the third battery voltage to obtain the third voltage drop; obtaining the ratio between the third voltage drop and the fourth preset time to obtain the K value of the battery.

[0015] According to one embodiment of the present application, the self-discharge state of the battery is evaluated according to the K value of the battery, including: when the K value of the battery is less than or equal to a preset K value, determining that the battery is in a normal self-discharge state; when the K value of the battery is greater than the preset K value, determining that the battery is in an abnormal self-discharge state.

[0016] According to one embodiment of the present application, charging a battery to a target SOC includes: performing a capacity division operation on the battery, and charging the battery after the capacity division operation to the target SOC based on constant current charging.

[0017] To achieve the above-mentioned purpose, a second aspect of the present application proposes a computer-readable storage medium on which a battery status evaluation program is stored. When the battery status evaluation program is executed by a processor, the above-mentioned battery status evaluation method is implemented.

[0018] According to the computer-readable storage medium of the embodiment of the present application, the above-mentioned battery status evaluation method is implemented when the battery status evaluation program is executed by the processor. Based on the above-mentioned battery status evaluation method, the battery is preliminarily screened twice based on the battery voltages obtained by standing at room temperature and standing at high temperature, so as to reduce the occurrence of missed screening of cells with large K values. At the same time, the polarization of the battery cells can be fully eliminated based on standing at room temperature and standing at high temperature, so that the obtained battery voltage is more precise, the K value calculation is more accurate, and the battery status evaluation effect is greatly improved.

[0019] To achieve the above-mentioned purpose, the third aspect of the present application proposes a battery state evaluation device, which includes: a first acquisition module, which is used to charge the battery to a target SOC and obtain a first battery voltage of the battery; a second acquisition module, which allows the battery to stand for a first preset time at a first preset temperature and obtain a second battery voltage of the battery after standing; a third acquisition module, which, when it is determined that the battery meets the first preset condition according to the first battery voltage and the second battery voltage, allows the battery to stand for a second preset time at the second preset temperature and for a third preset time at the first preset temperature in sequence, and obtains a third battery voltage of the battery after standing, wherein the second preset temperature is greater than the first preset temperature; a fourth acquisition module, which, when it is determined that the battery meets the second preset condition according to the second battery voltage and the third battery voltage, allows the battery to stand for a fourth preset time at the first preset temperature and obtain a fourth battery voltage of the battery after standing; a state evaluation module, which is used to determine the K value of the battery according to the fourth battery voltage, the third battery voltage and the fourth preset time, so as to evaluate the self-discharge state of the battery according to the K value of the battery.

[0020] According to the battery state evaluation device of the embodiment of the present application, the battery is charged to a target SOC through a first acquisition module, and the first battery voltage of the battery is obtained; the battery is allowed to stand at a first preset temperature for a first preset time through a second acquisition module, and the second battery voltage of the battery after standing is obtained; when it is determined through a third acquisition module that the battery meets a first preset condition based on the first battery voltage and the second battery voltage, the battery is allowed to stand at the second preset temperature for a second preset time and at the first preset temperature for a third preset time in sequence, and the third battery voltage of the battery after standing is obtained, wherein the second preset temperature is greater than the first preset temperature; when it is determined through a fourth acquisition module that the battery meets the second preset condition based on the second battery voltage and the third battery voltage, the battery is allowed to stand at the first preset temperature for a fourth preset time, and the fourth battery voltage of the battery after standing is obtained; the state evaluation module determines the K value of the battery based on the fourth battery voltage, the third battery voltage and the fourth preset time, so as to evaluate the self-discharge state of the battery based on the K value of the battery. Therefore, the device performs two preliminary screenings on the battery based on the battery voltages obtained at room temperature and high temperature, reducing the occurrence of missed screening of cells with large K values. At the same time, the polarization of the battery cells can be fully eliminated based on room temperature and high temperature, making the obtained battery voltage more precise and the K value calculation more accurate, greatly improving the battery status assessment effect.

[0021] 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

[0022] Figure 1 is a flow chart of a battery status evaluation method according to an embodiment of the present application;

[0023] Figure 2 is an open circuit voltage-temperature relationship curve according to a specific embodiment of the present application;

[0024] Figure 3 is a flow chart of a battery status evaluation method according to a specific embodiment of the present application;

[0025] Figure 4 Schematic diagram of the connection of a battery status assessment device according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] 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.

[0027] The following describes a battery status evaluation method, a computer-readable storage medium, and a battery status evaluation device proposed in embodiments of the present application with reference to the accompanying drawings.

[0028] Figure 1 The figure is a flow chart of a battery status evaluation method according to an embodiment of the present application.

[0029] like Figure 1 As shown, the battery status evaluation method of the embodiment of the present application may include:

[0030] S1, charging the battery to a target SOC and obtaining a first battery voltage OCV1 of the battery;

[0031] S2, leaving the battery at a first preset temperature for a first preset time, and obtaining a second battery voltage OCV2 of the battery after the standing time;

[0032] S3, when it is determined according to the first battery voltage OCV1 and the second battery voltage OCV2 that the battery meets the first preset condition, sequentially placing the battery at a second preset temperature for a second preset time and at a first preset temperature for a third preset time, and obtaining a third battery voltage of the battery after the standing time, wherein the second preset temperature is greater than the first preset temperature;

[0033] S4, when it is determined that the battery meets the second preset condition according to the second battery voltage OCV2 and the third battery voltage OCV3, the battery is allowed to stand for a fourth preset time at the first preset temperature, and a fourth battery voltage OCV4 of the battery after the standing time is obtained;

[0034] S5, determining a K value of the battery according to the fourth battery voltage OCV4, the third battery voltage OCV3 and a fourth preset time, so as to evaluate the self-discharge state of the battery according to the K value of the battery.

[0035] Specifically, the first battery voltage OCV1, the second battery voltage OCV2, the third battery voltage OCV3 and OCV4 are all open circuit voltages of the battery. Among them, the first battery voltage OCV1 is the initial open circuit voltage of the battery of the battery state evaluation method, that is, the battery voltage before step S2 is performed. Specifically, the battery is first charged to the target SOC, and the target SOC can be set according to the actual situation, such as 3%-35% SOC, to meet the discharge detection requirements in the subsequent static process, and then the open circuit voltage of the battery when charging is completed is obtained to obtain the first battery voltage OCV1 of the battery.

[0036] When the battery is at rest at the first preset temperature, it is at room temperature, which cools the battery on the one hand, and eliminates the polarization of the battery cell on the other hand. When the battery is at rest at the second preset temperature, it is at high temperature, which accelerates and fully eliminates the polarization of the battery cell based on the high temperature, so that the obtained battery voltage is more accurate and the calculated K value is more accurate. The specific temperature can be set according to the actual situation, for example, the first preset temperature is 25±2℃, and the second preset temperature is 45±2℃.

[0037] The first preset time length, the second preset time length, the third preset time length and the fourth preset time length are static time lengths, and the specific time can be set according to actual conditions. For example, the first preset time length is 6-12h, the second preset time length is 24-48h, the third preset time length is 12±1h, and the fourth preset time length is 96±2h.

[0038] The following takes the first preset temperature as 25±2°C, the second preset temperature as 45±2°C, the first preset time as 6h, the second preset time as 24h, the third preset time as 12h, and the fourth preset time as 96h as an example to describe the battery status evaluation method in detail.

[0039] First, when the battery is charged to 30%, stop charging the battery and obtain the open circuit voltage of the battery when charging is completed, that is, the first battery voltage OCV1. Then, let the battery stand at 25±2℃ for 6h. On the one hand, the battery is fully cooled based on standing at room temperature, and on the other hand, the polarization of the battery cell is eliminated, and the open circuit voltage of the battery after standing is obtained, that is, the second battery voltage OCV2. Then, according to the first battery voltage OCV1 and the second battery voltage OCV2, it is judged whether the battery voltage drop of the battery during the standing process meets the requirements. If it does, it is determined that the battery meets the first preset condition, and the following steps are continued; if not, it is determined that the battery is abnormal, and the first preset condition is met, and the following steps are no longer performed. This completes the first preliminary screening of the battery.

[0040] Then, the battery that meets the first preset condition is placed at 45±2℃ for 24h, i.e., high-temperature placement, so as to fully eliminate the polarization of the battery cell through high-temperature placement, and after the high-temperature placement, the battery is cooled at 25℃±2℃ for 12h, and the open circuit voltage of the battery after placement, i.e., the third battery voltage OCV3, is recorded. According to the second battery voltage OCV2 and the third battery voltage OCV3, it is judged whether the battery voltage drop during the placement process meets the requirements. If so, it is determined that the battery meets the second preset condition, and the following steps are continued; if not, it is determined that the battery is abnormal and does not meet the second preset condition, and the following steps are no longer performed. The second preliminary screening of the battery is thus completed.

[0041] Then, the battery meeting the second preset condition is placed at 25°C ± 2°C for 96 hours, and the open circuit voltage of the battery, i.e., the fourth battery voltage OCV4, is tested. The rate of decrease of the battery voltage within 96 hours is determined based on the fourth battery voltage OCV4 and the third battery voltage OCV3, so as to calculate the K value of the battery, and evaluate the self-discharge state of the battery based on the K value of the battery. Among them, if the K value is too large, it means that the battery storage voltage decreases too fast, and it is considered that the battery has self-discharge abnormality.

[0042] Therefore, this embodiment performs two preliminary screenings before obtaining the K value to reduce the number of cells with large K values ​​that are missed. At the same time, normal temperature standing and high temperature standing are added before calculating the K value to fully eliminate the polarization of the battery cells, so that the obtained battery voltage is more accurate and the K value calculation is more accurate.

[0043] In one embodiment of the present application, charging a battery to a target SOC includes: performing a capacity division operation on the battery, and charging the battery after the capacity division operation to the target SOC based on constant current charging.

[0044] For example, the battery to be tested is charged after capacity division and then charged to 30% SOC at a low current of 0.2C in an environment of 25±2°C, and the instantaneous open circuit voltage of the battery after charging is recorded to obtain the first battery voltage OCV1 of the battery.

[0045] In one embodiment of the present application, after obtaining the battery voltage, the method includes: obtaining the current battery temperature of the battery; and correcting the battery voltage based on the current battery temperature and the first preset temperature.

[0046] That is to say, after obtaining the first battery voltage OCV1, the second battery voltage OCV2, the third battery voltage OCV3 and the fourth battery voltage OCV4 of the battery, the measured battery voltage is corrected and calibrated based on the current battery temperature when the corresponding battery voltage is obtained and the first preset temperature, so that the obtained battery voltage is more accurate, which is used for the initial screening judgment and K value calculation in the evaluation process, so that the evaluation result is more accurate. Among them, the current battery temperature can be obtained by contacting the battery cover with the temperature probe of the OCV tester.

[0047] In one embodiment of the present application, the battery voltage is corrected based on the current battery temperature and the first preset temperature, including: obtaining the difference between the current battery temperature and the first preset temperature to obtain the first temperature; obtaining the product of the first temperature and the preset temperature compensation coefficient to obtain the compensation voltage; obtaining the sum of the battery voltage and the compensation voltage to obtain the corrected battery voltage.

[0048] Specifically, the preset temperature compensation coefficient may be determined based on an experiment. For example, a method for obtaining the preset temperature compensation coefficient includes the following steps:

[0049] S21, placing the lithium-ion battery cells after capacity replenishment in a constant temperature box, adjusting the temperature in the constant temperature box to 22°C, 25°C, 27°C, 29°C, and 31°C for temperature increase testing;

[0050] S22, standing at each constant temperature for 4 hours, collecting the open circuit voltage (OCV) of the battery after standing;

[0051] S32, then adjust the temperature in the constant temperature box to 31°C, 29°C, 27°C, 25°C, and 22°C for cooling test;

[0052] S24, standing at each constant temperature for 4 hours, collecting the open circuit voltage (OCV) of the battery after standing;

[0053] S25, calculate the average OCV of the OCV at the same temperature during the heating and cooling process to eliminate the influence of the battery storage time at different temperatures;

[0054] S26, drawing -temperature curve, obtain the linear fitting function, and obtain the relationship between the battery open circuit voltage OCV and temperature. Assume that the relationship between the battery open circuit voltage OCV and temperature obtained based on the linear fitting is as follows Figure 2 As shown, the preset temperature compensation coefficient is determined to be 0.0992, and the preset calculation equation for the corrected battery voltage is:

[0055] OCV 修正 =OCV+(T-25)*0.0992 (1)

[0056] Among them, OCV 修正 is the corrected battery voltage, OCV is the measured battery voltage, T is the battery cell temperature, and 25 is the first preset temperature.

[0057] For example, when charging the battery to the target SOC, the first battery voltage OCV1 and the current battery temperature T1 at the end of charging are obtained, and the first battery voltage OCV1 and the current battery temperature T1 are substituted into formula (1) to calculate the corrected first battery voltage OCV 1修正 Then, the battery is left at a first preset temperature for a first preset time, and the second battery voltage OCV2 and the current battery temperature T2 after the rest are obtained. The second battery voltage OCV2 and the battery temperature T2 are substituted into formula (1) to calculate the corrected second battery voltage OCV 2修正 According to the battery voltage OCV 1修正 and battery voltage OCV 2修正When it is determined that the battery meets the first preset condition, the battery is left at rest for a second preset time at a second preset temperature and for a third preset time at a first preset temperature, and a third battery voltage OCV3 and a current battery temperature T3 of the battery after rest are obtained. The third battery voltage OCV3 and the battery temperature T3 are substituted into formula (1) to calculate a corrected third battery voltage OCV 3修正 According to the battery voltage OCV 2修正 and battery voltage OCV 3修正 When it is determined that the battery meets the second preset condition, the battery is left at the first preset temperature for a fourth preset time, and the fourth battery voltage OCV4 and the current battery temperature T4 after the rest are obtained. The fourth battery voltage OCV4 and the battery temperature T4 are substituted into formula (1) to calculate the corrected fourth battery voltage OCV 4修正 Finally, according to the battery voltage OCV 4修正 、Battery voltage OCV 3修正 And a fourth preset time length determines a K value of the battery, so as to evaluate the self-discharge state of the battery according to the K value of the battery.

[0058] In one embodiment of the present application, determining that a battery satisfies a first preset condition based on a first battery voltage OCV1 and a second battery voltage OCV2 includes: obtaining a difference between the first battery voltage OCV1 and the second battery voltage OCV2 to obtain a first voltage drop, and determining that the battery satisfies the first preset condition when the first voltage drop is less than or equal to the first preset voltage drop.

[0059] Specifically, the first preset voltage drop can be set according to actual conditions, or can be determined based on the difference between the first battery voltage and the second battery voltage obtained by testing each battery in the same batch of batteries. For example, the first preset voltage drop is Assuming that there are n batteries in the same batch as the battery, the above test is performed on the n batteries respectively to obtain the first battery voltage OCV of each battery. 1i and the second battery voltage OCV 2-i , then calculate the first cell voltage OCV of each cell 1-i and the second battery voltage OCV 2-i The difference △OCV 1-i =OCV 1-i -OCV 2-i , the △OCV of n batteries 1-i Take the average calculation to get Calculate △OCV of n batteries simultaneously 1-i The standard deviation of σ1 is obtained, and the first preset voltage drop is calculated

[0060] Obtain the difference between the first battery voltage OCV1 and the second battery voltage OCV2 of the battery, that is, the first voltage drop △OCV1. If Then it is considered that the battery meets the first preset condition, that is, the battery passes the first preliminary screening. Then it is considered that the battery does not meet the first preset condition, has abnormal self-discharge, and fails the first preliminary screening.

[0061] In one embodiment of the present application, determining whether a battery satisfies a second preset condition based on a second battery voltage OCV2 and a third battery voltage OCV3 includes: obtaining a difference between the second battery voltage OCV2 and the third battery voltage OCV3 to obtain a second voltage drop, and determining that the battery satisfies the second preset condition when the second voltage drop is less than or equal to the second preset voltage drop.

[0062] Specifically, the second preset voltage drop can be set according to actual conditions. Referring to the method for determining the first preset voltage drop, the second preset voltage drop can also be determined based on the difference between the second battery voltage and the third battery voltage obtained by testing each battery in the same batch of batteries. For example, the second preset voltage drop is Assuming that there are a total of n batteries in the same batch as the battery, the above test is performed on the n batteries respectively to obtain the second battery voltage OCV of each battery. 2-i and the third battery voltage OCV 3-i , then calculate the second battery voltage OCV of each battery 2-i and the third battery voltage OCV 3-i The difference △OCV 2-i =OCV 2-i -OCV 3-i , the △OCV of n batteries 2-i Take the average calculation to get Calculate △OCV of n batteries simultaneously 2-i The standard deviation is taken to get σ2, which is then calculated to be below the preset voltage threshold

[0063] Obtain the difference between the second battery voltage OCV2 and the third battery voltage OCV3 of the battery, that is, the second voltage drop △OCV2. If Then it is considered that the battery meets the second preset condition, that is, the battery passes the second preliminary screening. Then it is considered that the battery does not meet the second preset condition, has abnormal self-discharge, and fails the second preliminary screening.

[0064] In one embodiment of the present application, the K value of the battery is determined according to the fourth battery voltage OCV4, the third battery voltage OCV3 and the fourth preset time, including: obtaining the voltage difference between the fourth battery voltage OCV4 and the third battery voltage OCV3 to obtain the third voltage drop; obtaining the ratio between the third voltage drop and the fourth preset time to obtain the K value of the battery.

[0065] That is, the K value of the battery=(OCV4-OCV3) / Δt, wherein Δt is the number of hours between OCV3 and OCV4, ie, the fourth preset time length.

[0066] In one embodiment of the present application, the self-discharge state of the battery is evaluated according to the K value of the battery, including: when the K value of the battery is less than or equal to a preset K value, determining that the battery is in a normal self-discharge state; when the K value of the battery is greater than the preset K value, determining that the battery is in an abnormal self-discharge state.

[0067] Specifically, the preset K value can be set based on actual conditions. Taking the preset K value of 0.028mv / h as an example, if the calculated actual K value of the battery is >0.028mv / h, the battery is an abnormal self-discharge battery; if the actual K value of the battery is ≤0.028mv / h, the battery is a normal battery.

[0068] As a specific embodiment of the present application, the target SOC is 30% SOC, the first preset temperature is 25±2°C, the second preset temperature is 45±2°C, the first preset time is 6h, the second preset time is 24h, the third preset time is 12h, the fourth preset time is 96h, the preset temperature compensation coefficient is 0.0992, the first preset voltage drop is ΔOCV1+3σ1, the second preset voltage drop is ΔOCV2+3σ2, and the preset K value is 0.028mv / h. Figure 3 As shown, the battery status assessment method may include the following steps:

[0069] Phase 1:

[0070] S101, recharge the battery after capacity division, charge it to 30% SOC at a low current of 0.2C at 25±2°C, and record the instantaneous battery voltage OCV1 after charging and the current battery temperature T1.

[0071] S102, OCV 1修正 =OCV1+(T1-25)*0.0992.

[0072] S103, leaving the battery at 25±2°C for 6 hours, recording the battery voltage OCV2 and the current battery temperature T2.

[0073] S104, OCV 2修正=OCV2+(T2-25)*0.0992.

[0074] S105, △OCV1=OCV 1修正 -OCV 2修正 .

[0075] S106, determine whether ΔOCV1 is less than or equal to ΔOCV1+3σ1. If yes, execute step S107; if no, execute step S117.

[0076] Phase 2:

[0077] S107, transfer the battery to a high temperature room and place it at 45±2℃ for 24h.

[0078] S108, the battery is cooled at 25°C ± 2°C for 12 hours, and the battery voltage OCV3 and the current battery temperature T3 are recorded.

[0079] S109, OCV 3修正 =OCV3+(T3-25)*0.0992.

[0080] S110, △OCV2=OCV 2修正 -OCV 3修正 .

[0081] S111, determine whether ΔOCV2 is less than or equal to ΔOCV2+3σ2. If yes, execute step S112; if no, execute step S117.

[0082] Phase 3:

[0083] S112, after the battery is left at 25℃±2℃ for 96h, the battery voltage OCV4 and the current battery temperature T4 are tested.

[0084] S113, OCV 4修正 =OCV4+(T4-25)*0.0992.

[0085] S114, battery K value = (OCV 4修正 -OCV 3修正 ) / 96.

[0086] S115, determine whether the K value of the battery is less than or equal to 0.028mv / h. If yes, execute step S116; if no, execute step S117.

[0087] S116, determining that the battery is in an abnormal self-discharge state.

[0088] S117, determining that the battery is in a normal self-discharging state.

[0089] Therefore, the battery status evaluation method is divided into three stages. The first stage is to test the OCV drop at room temperature after capacity division and passivation for screening; the second stage is to test the OCV drop at high temperature and passivation for screening; the third stage is to test OCV4 at room temperature and calculate the K value for screening to obtain the final qualified battery.

[0090] In summary, according to the battery state evaluation method of the embodiment of the present application, the battery is first charged to a target SOC, and a first battery voltage after charging is obtained, and then the battery is left to stand at a first preset temperature for a first preset time, and a second battery voltage after standing is obtained, and when it is determined that the battery meets the first preset condition according to the first battery voltage and the second battery voltage, the battery is left to stand at the second preset temperature for a second preset time and at the first preset temperature for a third preset time in sequence, and the third battery voltage after standing is obtained, wherein the second preset temperature is greater than the first preset temperature, and when it is determined that the battery meets the second preset condition according to the second battery voltage and the third battery voltage, the battery is left to stand at the first preset temperature for a fourth preset time, and a fourth battery voltage after standing is obtained; the K value of the battery is determined according to the fourth battery voltage and the third battery voltage, so as to evaluate the self-discharge state of the battery according to the K value of the battery. Therefore, the method performs two preliminary screenings on the battery based on the battery voltages obtained by standing at room temperature and at high temperature, thereby reducing the occurrence of missed screening of cells with large K values. At the same time, the polarization of the battery cells can be fully eliminated based on standing at room temperature and at high temperature, so that the obtained battery voltage is more precise and the K value calculation is more accurate, which greatly improves the battery status assessment effect.

[0091] Corresponding to the above embodiments, the present application also proposes a computer-readable storage medium.

[0092] The computer-readable storage medium of the embodiment of the present application stores a battery status evaluation program, and the battery status evaluation program implements the above-mentioned battery status evaluation method when executed by a processor.

[0093] According to the computer-readable storage medium of the embodiment of the present application, the above-mentioned battery status evaluation method is implemented when the battery status evaluation program is executed by the processor. Based on the above-mentioned battery status evaluation method, the battery is preliminarily screened twice based on the battery voltages obtained by standing at room temperature and standing at high temperature, so as to reduce the occurrence of missed screening of cells with large K values. At the same time, the polarization of the battery cells can be fully eliminated based on standing at room temperature and standing at high temperature, so that the obtained battery voltage is more precise, the K value calculation is more accurate, and the battery status evaluation effect is greatly improved.

[0094] Corresponding to the above embodiments, the present application also proposes a battery status evaluation device.

[0095] like Figure 4As shown, the battery status evaluation device of the embodiment of the present application may include: a first acquisition module 10 , a second acquisition module 20 , a third acquisition module 30 , a fourth acquisition module 40 and a status evaluation module 50 .

[0096] Among them, the first acquisition module 10 is used to charge the battery to the target SOC and obtain the first battery voltage of the battery. The second acquisition module 20 allows the battery to stand for a first preset time at a first preset temperature and obtain the second battery voltage after standing. The third acquisition module 30, when determining that the battery meets the first preset condition according to the first battery voltage and the second battery voltage, allows the battery to stand for a second preset time at the second preset temperature and for a third preset time at the first preset temperature in sequence, and obtains the third battery voltage after standing, wherein the second preset temperature is greater than the first preset temperature. The fourth acquisition module 40, when determining that the battery meets the second preset condition according to the second battery voltage and the third battery voltage, allows the battery to stand for a fourth preset time at the first preset temperature and obtain the fourth battery voltage after standing. The state evaluation module 50 is used to determine the K value of the battery according to the fourth battery voltage and the third battery voltage, so as to evaluate the self-discharge state of the battery according to the K value of the battery.

[0097] According to one embodiment of the present application, the first acquisition module 10, the second acquisition module 20, the third acquisition module 30 and the fourth acquisition module 40 are also respectively provided with a correction unit. After acquiring the battery voltage, the correction unit is used to obtain the current battery temperature of the battery; and correct the battery voltage based on the current battery temperature and the first preset temperature.

[0098] According to one embodiment of the present application, the correction unit corrects the battery voltage based on the current battery temperature and the first preset temperature, and is specifically used to: obtain the difference between the current battery temperature and the first preset temperature to obtain the first temperature; obtain the product of the first temperature and the preset temperature compensation coefficient to obtain the compensation voltage; obtain the sum of the battery voltage and the compensation voltage to obtain the corrected battery voltage.

[0099] According to one embodiment of the present application, the third acquisition module 30 determines that the battery meets the first preset condition based on the first battery voltage and the second battery voltage, and is specifically used to: obtain the difference between the first battery voltage and the second battery voltage to obtain a first voltage drop, and determine that the battery meets the first preset condition when the first voltage drop is less than or equal to the first preset voltage drop.

[0100] According to one embodiment of the present application, the fourth acquisition module 40 determines that the battery meets the second preset condition based on the second battery voltage and the third battery voltage, and is specifically used to: obtain the difference between the second battery voltage and the third battery voltage to obtain a second voltage drop, and determine that the battery meets the second preset condition when the second voltage drop is less than or equal to the second preset voltage drop.

[0101] According to one embodiment of the present application, the status evaluation module 50 determines the K value of the battery based on the fourth battery voltage, the third battery voltage and the fourth preset time, and is specifically used to: obtain the difference between the fourth battery voltage and the third battery voltage to obtain the third voltage drop; obtain the ratio between the third voltage drop and the fourth preset time to obtain the K value of the battery.

[0102] According to one embodiment of the present application, the status evaluation module 50 evaluates the self-discharge status of the battery according to the K value of the battery, and is specifically used to: when the K value of the battery is less than or equal to a preset K value, determine that the battery is in a normal self-discharge state; when the K value of the battery is greater than the preset K value, determine that the battery is in an abnormal self-discharge state.

[0103] According to an embodiment of the present application, the first acquisition module 10 charges the battery to a target SOC, and is specifically used to: perform a capacity division operation on the battery, and replenish the battery after the capacity division operation to the target SOC based on constant current charging.

[0104] It should be noted that for details not disclosed in the battery status evaluation device of the embodiment of the present application, please refer to the details disclosed in the battery status evaluation method of the above embodiment of the present application, and the details will not be repeated here.

[0105] According to the battery state evaluation device of the embodiment of the present application, the battery is charged to a target SOC through a first acquisition module, and a first battery voltage after charging is obtained; the battery is allowed to stand at a first preset temperature for a first preset time through a second acquisition module, and a second battery voltage after standing is obtained; when it is determined through a third acquisition module that the battery meets a first preset condition based on the first battery voltage and the second battery voltage, the battery is allowed to stand at the second preset temperature for a second preset time and at the first preset temperature for a third preset time in sequence, and the third battery voltage after standing is obtained, wherein the second preset temperature is greater than the first preset temperature; when it is determined through a fourth acquisition module that the battery meets the second preset condition based on the second battery voltage and the third battery voltage, the battery is allowed to stand at the first preset temperature for a fourth preset time, and a fourth battery voltage after standing is obtained; the state evaluation module determines a K value of the battery based on the fourth battery voltage, the third battery voltage and the fourth preset time, so as to evaluate the self-discharge state of the battery based on the K value of the battery. Therefore, the device performs two preliminary screenings on the battery based on the battery voltages obtained at room temperature and high temperature, reducing the occurrence of missed screening of cells with large K values. At the same time, the polarization of the battery cells can be fully eliminated based on room temperature and high temperature, making the obtained battery voltage more precise and the K value calculation more accurate, greatly improving the battery status assessment effect.

[0106] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented 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 purposes 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 portion with one or more wirings (electronic device), 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), an optical fiber 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 processing in other suitable ways if necessary, and then stored in a computer memory.

[0107] 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 embodiments, multiple 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.

[0108] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" 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 representation of the above terms does 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 more embodiments or examples in a suitable manner.

[0109] 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 the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0110] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0111] 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 limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A battery status assessment method, characterized in that: The method comprises: charging the battery to a target SOC and acquiring a first battery voltage of the battery; Allowing the battery to stand for a first preset time at a first preset temperature, and obtaining a second battery voltage of the battery after the standing time; When it is determined that the battery meets a first preset condition according to the first battery voltage and the second battery voltage, the battery is sequentially placed at a second preset temperature for a second preset time and at the first preset temperature for a third preset time, and a third battery voltage of the battery after the placement is obtained, wherein the second preset temperature is greater than the first preset temperature; When it is determined that the battery meets a second preset condition according to the second battery voltage and the third battery voltage, leaving the battery at a first preset temperature for a fourth preset time, and obtaining a fourth battery voltage of the battery after the leaving time; The K value of the battery is determined according to the fourth battery voltage, the third battery voltage, and the fourth preset time, so as to evaluate the self-discharge state of the battery according to the K value of the battery.

2. The battery status evaluation method according to claim 1, characterized in that: After obtaining the battery voltage, the method includes: Obtaining a current battery temperature of the battery; The battery voltage is corrected based on the current battery temperature and the first preset temperature.

3. The battery status evaluation method according to claim 2, characterized in that: The correcting the battery voltage based on the current battery temperature and the first preset temperature includes: Obtaining a difference between the current battery temperature and the first preset temperature to obtain a first temperature; Obtaining the product of the first temperature and a preset temperature compensation coefficient to obtain a compensation voltage; The sum of the battery voltage and the compensation voltage is obtained to obtain a corrected battery voltage.

4. The battery status evaluation method according to claim 1, characterized in that: The determining, according to the first battery voltage and the second battery voltage, that the battery meets a first preset condition includes: A difference between the first battery voltage and the second battery voltage is obtained to obtain a first voltage drop, and when the first voltage drop is less than or equal to a first preset voltage drop, it is determined that the battery meets a first preset condition.

5. The battery status evaluation method according to claim 1, characterized in that: The determining, according to the second battery voltage and the third battery voltage, that the battery meets a second preset condition comprises: A difference between the second battery voltage and the third battery voltage is obtained to obtain a second voltage drop, and when the second voltage drop is less than or equal to a second preset voltage drop, it is determined that the battery meets a second preset condition.

6. The battery status evaluation method according to claim 1, characterized in that: The determining the K value of the battery according to the fourth battery voltage, the third battery voltage and the fourth preset time includes: acquiring a voltage difference between the fourth battery voltage and the third battery voltage to obtain a first voltage; The ratio of the first voltage to the fourth preset time period is obtained to obtain the K value of the battery.

7. The battery status evaluation method according to claim 1, characterized in that: The step of evaluating the self-discharge state of the battery according to the K value of the battery includes: When the K value of the battery is less than or equal to a preset K value, determining that the battery is in a normal self-discharge state; When the K value of the battery is greater than a preset K value, it is determined that the battery is in an abnormal self-discharge state.

8. The battery status evaluation method according to any one of claims 1 to 7, characterized in that: The step of charging the battery to a target SOC comprises: The battery is subjected to a capacity division operation, and the battery after the capacity division operation is charged to a target SOC based on constant current charging.

9. A computer-readable storage medium, characterized in that: A battery status evaluation program is stored thereon, and when the battery status evaluation program is executed by a processor, the battery status evaluation method according to any one of claims 1 to 8 is implemented.

10. A battery status evaluation device, characterized in that: The device comprises: A first acquisition module, used for charging the battery to a target SOC and acquiring a first battery voltage of the battery; a second acquisition module, which allows the battery to stand at a first preset temperature for a first preset time, and acquires a second battery voltage of the battery after the standing time; a third acquisition module, when it is determined according to the first battery voltage and the second battery voltage that the battery satisfies a first preset condition, placing the battery at a second preset temperature for a second preset time and at the first preset temperature for a third preset time, and acquiring a third battery voltage of the battery after the standing time, wherein the second preset temperature is greater than the first preset temperature; a fourth acquisition module, which, when it is determined according to the second battery voltage and the third battery voltage that the battery satisfies a second preset condition, allows the battery to stand for a fourth preset time at a first preset temperature, and acquires a fourth battery voltage of the battery after the standing time; A state evaluation module is used to determine the K value of the battery according to the fourth battery voltage, the third battery voltage and the fourth preset time, so as to evaluate the self-discharge state of the battery according to the K value of the battery.

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