Method and System for Evaluating the State of Aging Batteries Based on Thermal Safety

Abstract

The present invention belongs to the technical field of battery safety detection, and discloses a method and system for evaluating the state of aged batteries based on thermal safety. The method includes: collecting parameter information of multiple different aged battery cells of the same specification; performing standard capacity tests and thermal runaway tests on multiple different aged battery cells and calculating electrochemical performance indicators and thermal safety risk indicators based on the parameter information; obtaining historical test data of multiple different aged battery cells under different working conditions, and calculating characteristic values according to the historical test data; constructing a regression model of the electrochemical performance indicators, the thermal safety risk indicators and the characteristic values. In this way, an evaluation model of characteristic values, battery electrochemical performance and thermal safety risk can be established through simple electrical performance experiments, and finally a non-destructive, fast and comprehensive evaluation of the state of aged batteries can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of battery safety detection, and particularly to a method and system for evaluating the state of an aged battery based on thermal safety. Background Art

[0002] Currently, the evaluation indicators of battery state generally include: SOH (State of Health), SOP (State of Power), RUL (Remaining Useful Life), SOE (State of Energy), etc. However, regardless of which indicator, the ultimate key parameter is the electrochemical performance indicator of the battery, such as capacity, internal resistance, self-discharge rate, output power, and so on.

[0003] In recent years, with the rapid expansion of the new energy vehicle market, the "thermal runaway" problem of lithium batteries has become the focus of public attention. Therefore, whether it is indicators such as SOP and SOE concerned in the battery management system, or indicators such as SOH and RUL often concerned in the echelon utilization scenario, the consideration of thermal safety risks of the battery is ignored in these evaluation processes, which will leave hidden dangers for the safe operation management of the battery.

[0004] However, the conventional thermal safety performance needs to be evaluated through tests such as thermal runaway, high and low temperature shock, heating, and fire. Such experiments will cause irreversible damage to the battery.

[0005] The above content is only used to assist in understanding the technical solution of the present invention, and does not represent an admission that the above content is prior art. Summary of the Invention

[0006] The main purpose of the present invention is to provide a method and system for evaluating the state of an aged battery based on thermal safety, aiming to solve the technical problem that the current test for the thermal safety performance of the battery will cause irreversible damage to the battery.

[0007] To achieve the above purpose, the present invention provides a method for evaluating the state of an aged battery based on thermal safety. The method for evaluating the state of an aged battery based on thermal safety includes the following steps:

[0008] Perform tests on the aged battery to be evaluated under different working conditions in sequence to obtain the current test data;

[0009] Calculate the corresponding characteristic values according to the current test data;

[0010] Substitute the calculated characteristic values into the constructed regression model to obtain the current electrochemical performance indicator and the current thermal safety risk indicator corresponding to the aged battery to be evaluated;

[0011] Perform a state assessment on the aging battery to be evaluated based on the current electrochemical performance index and the current thermal safety risk index.

[0012] In some embodiments, the method further includes:

[0013] Collect parameter information of multiple different aging battery cells of the same specification;

[0014] Perform a standard capacity test and a thermal runaway test on multiple different aging battery cells and calculate the electrochemical performance index and the thermal safety risk index based on the parameter information;

[0015] Obtain historical test data of multiple different aging battery cells under different working conditions and calculate characteristic values according to the historical test data;

[0016] Construct a regression model of the electrochemical performance index, the thermal safety risk index and the characteristic values.

[0017] In some embodiments, the performing a standard capacity test and a thermal runaway test on multiple different aging battery cells and calculating the electrochemical performance index and the thermal safety risk index based on the parameter information includes:

[0018] Obtain the standard capacity through a standard capacity test;

[0019] Determine the rated capacity based on the parameter information;

[0020] Calculate the electrochemical performance index according to the standard capacity and the rated capacity;

[0021] Obtain the self-heating temperature of the battery, the thermal runaway trigger temperature and the trigger time interval from the battery's self-heating to thermal runaway through a thermal runaway test;

[0022] Calculate the thermal safety risk index according to the self-heating temperature of the battery, the thermal runaway trigger temperature and the trigger time interval.

[0023] In some embodiments, the calculating the corresponding characteristic values according to the current test data includes:

[0024] Obtain the time taken for the aging battery to be evaluated to rise from a first preset voltage to the charging cut-off voltage from the current test data, and determine a first characteristic value according to the time, where the first characteristic value represents the charging duration;

[0025] Obtain the voltage at a preset moment before reaching the charging cut-off voltage from the current test data, and determine a second characteristic value according to the voltage at the preset moment before reaching the charging cut-off voltage, where the second characteristic value is the difference between the voltage at the preset moment before reaching the charging cut-off voltage and the charging cut-off voltage, representing the voltage rise amplitude under the constant current charging condition;

[0026] Obtain the time taken for the aging battery to be evaluated to discharge at a constant current from the second preset voltage to the third preset voltage from the current test data, and determine a third characteristic value according to the time. The third characteristic value represents the discharge duration. The second preset voltage and the third preset voltage are determined by the voltages after discharging at a constant current of 1C, and the second preset voltage is greater than the third preset voltage. The voltages after discharging at a constant current of 1C are determined by the charging cut-off voltage and the discharging cut-off voltage obtained from the current test data;

[0027] Obtain the capacity discharged from the fourth preset voltage to the fifth preset voltage from the test data, and determine a fourth characteristic value according to the discharged capacity. The fourth preset voltage and the fifth preset voltage are determined by the charging cut-off voltage, and the fourth preset voltage is greater than the fifth preset voltage.

[0028] In some embodiments, the state evaluation of the aging battery to be evaluated based on the current electrochemical performance index and the current thermal safety risk index includes:

[0029] Calculate the state score of the aging battery to be evaluated according to the current electrochemical performance index and the current thermal safety risk index. The calculation formula is where A and B are the respective weights corresponding to the electrochemical performance index and the thermal safety risk index, and are the current electrochemical performance index and the current thermal safety risk index respectively.

[0030] In addition, to achieve the above object, the present invention also proposes a state evaluation device for an aging battery based on thermal safety. The state evaluation device for an aging battery based on thermal safety includes:

[0031] An acquisition module, configured to perform tests on the aging battery to be evaluated under different working conditions in sequence to obtain current test data;

[0032] A processing module, configured to calculate corresponding characteristic values according to the current test data;

[0033] The processing module is configured to substitute the calculated characteristic values into a pre-constructed regression model to obtain the current electrochemical performance index and the current thermal safety risk index corresponding to the aging battery to be evaluated;

[0034] An evaluation module, configured to perform state evaluation on the aging battery to be evaluated based on the current electrochemical performance index and the current thermal safety risk index.

[0035] In some embodiments, the system further includes a construction module;

[0036] The building block is used to collect parameter information of multiple different aged battery cells of the same specification;

[0037] Perform standard capacity tests and thermal runaway tests on multiple different aged battery cells and calculate electrochemical performance indicators and thermal safety risk indicators based on the parameter information;

[0038] Obtain historical test data of multiple different aged battery cells under different working conditions and calculate characteristic values according to the historical test data;

[0039] Construct a regression model of the electrochemical performance indicator, the thermal safety risk indicator and the characteristic value.

[0040] In some embodiments, the processing module is used to obtain the standard capacity through a standard capacity test;

[0041] Determine the rated capacity based on the parameter information;

[0042] Calculate the electrochemical performance indicator according to the standard capacity and the rated capacity;

[0043] Obtain the self-generated heat temperature of the battery, the thermal runaway trigger temperature and the trigger time interval from the self-generated heat of the battery to thermal runaway through a thermal runaway test;

[0044] Calculate the thermal safety risk indicator according to the self-generated heat temperature of the battery, the thermal runaway trigger temperature and the trigger time interval.

[0045] In some embodiments, the processing module is used to obtain the time taken for the aging battery to be evaluated to rise from a first preset voltage to the charging cut-off voltage from the current test data, and determine a first characteristic value according to the time, where the first characteristic value represents the charging duration;

[0046] Obtain the voltage at a preset moment before reaching the charging cut-off voltage from the current test data, and determine a second characteristic value according to the voltage at the preset moment before reaching the charging cut-off voltage, where the second characteristic value is the difference between the voltage at the preset moment before reaching the charging cut-off voltage and the charging cut-off voltage, representing the voltage rise amplitude under the constant current charging condition;

[0047] Obtain the time taken for the aging battery to be evaluated to discharge at a constant current from a second preset voltage to a third preset voltage from the current test data, and determine a third characteristic value according to the time, where the third characteristic value represents the discharge duration, and the second preset voltage and the third preset voltage are determined by the voltage after discharging at a constant current of 1C and the second preset voltage is greater than the third preset voltage, and the voltage after discharging at a constant current of 1C is determined by the charging cut-off voltage and the discharging cut-off voltage obtained from the current test data;

[0048] Obtain the capacity released from the fourth preset voltage to the fifth preset voltage from the test data, and determine a fourth characteristic value according to the released capacity. The fourth preset voltage and the fifth preset voltage are determined by the charging cut-off voltage and the fourth preset voltage is greater than the fifth preset voltage.

[0049] In some embodiments, the evaluation module is configured to calculate a state score of the to-be-evaluated aged battery according to the current electrochemical performance index and the current thermal safety risk index. The calculation formula is , where A and B are the respective weights corresponding to the electrochemical performance index and the thermal safety risk index, and are the current electrochemical performance index and the current thermal safety risk index respectively.

[0050] In the present invention, parameter information of multiple different aged battery cells of the same specification is collected; standard capacity tests and thermal runaway tests are performed on the multiple different aged battery cells, and the electrochemical performance index and the thermal safety risk index are calculated based on the parameter information; historical test data of the multiple different aged battery cells under different working conditions are obtained, and characteristic values are calculated according to the historical test data; a regression model of the electrochemical performance index, the thermal safety risk index and the characteristic value is constructed. By the above method, an evaluation model of the characteristic value, the battery electrochemical performance and the thermal safety risk can be established through simple electrical performance experiments, and finally a non-destructive, fast and comprehensive evaluation of the state of the aged battery can be realized. Description of the Drawings

[0051] Figure 1 is a schematic flowchart of the first embodiment of the method for evaluating the state of an aged battery based on thermal safety according to the present invention;

[0052] Figure 2 is the thermal runaway temperature curve in the method for evaluating the state of an aged battery based on thermal safety according to the present invention;

[0053] Fig. 3(a) shows the change law of the aging degree F1 in the method for evaluating the state of an aged battery based on thermal safety according to the present invention;

[0054] Fig. 3(b) shows the change law of the aging degree F2 in the method for evaluating the state of an aged battery based on thermal safety according to the present invention;

[0055] Fig. 4(a) shows the change law of the aging degree F3 in the method for evaluating the state of an aged battery based on thermal safety according to the present invention;

[0056] Fig. 4(b) shows the change law of the aging degree F4 in the method for evaluating the state of an aged battery based on thermal safety according to the present invention;

[0057] Figure 5 is a structural block diagram of the first embodiment of the system for evaluating the state of an aged battery based on thermal safety according to the present invention.

[0058] The realization, functional features and advantages of the present invention will be further described in conjunction with embodiments with reference to the accompanying drawings. Detailed implementation manners

[0059] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0060] An embodiment of the present invention provides a method for evaluating the state of an aged battery based on thermal safety. Refer to Figure 1 , Figure 1 which is a schematic flowchart of the first embodiment of a method for evaluating the state of an aged battery based on thermal safety according to the present invention.

[0061] In this embodiment, the method for evaluating the state of an aged battery based on thermal safety includes the following steps:

[0062] Step S10: Test the aged battery to be evaluated under different working conditions in sequence to obtain current test data.

[0063] In this embodiment, the execution subject of this embodiment is a device for evaluating the state of an aged battery based on thermal safety. Among them, the device for evaluating the state of an aged battery based on thermal safety has functions such as data processing, data communication, and program operation. The device for evaluating the state of an aged battery based on thermal safety can be a computer terminal device or other network devices. Of course, it can also be other devices with similar functions. This embodiment does not make any restrictions on this.

[0064] Currently, the evaluation indicators of battery state generally include: SOH (State of Health), SOP (State of Power), RUL (Remaining Useful Life), SOE (State of Energy), etc. However, no matter which indicator, the ultimate key parameters are the electrochemical performance indicators of the battery, such as capacity, internal resistance, self-discharge rate, output power, etc. In recent years, with the rapid expansion of the new energy vehicle market, the "thermal runaway" problem of lithium batteries has become the focus of public attention. Therefore, whether it is indicators such as SOP and SOE concerned in the battery management system, or indicators such as SOH and RUL often concerned in the face of the echelon utilization scenario, the consideration of the thermal safety risk of the battery is ignored in these evaluation processes, which will leave hidden dangers for the safe operation management of the battery. However, the conventional thermal safety performance needs to be evaluated through tests such as thermal runaway, high and low temperature shock, heating, and fire. Such experiments will cause irreversible damage to the battery.

[0065] To solve the above technical problems, in this embodiment, parameter information of multiple different aged battery cells of the same specification is collected; standard capacity tests and thermal runaway tests are performed on multiple different aged battery cells, and electrochemical performance indicators and thermal safety risk indicators are calculated based on the parameter information; historical test data of multiple different aged battery cells under different working conditions are obtained, and eigenvalues are calculated according to the historical test data; a regression model of the electrochemical performance indicators, the thermal safety risk indicators, and the eigenvalues is constructed. In this way, through simple electrical performance experiments, an evaluation model of the eigenvalues, battery electrochemical performance, and thermal safety risk can be established, and ultimately a non-destructive, fast, and comprehensive evaluation of the state of aged batteries can be achieved. Specifically, it can be implemented in the following manner.

[0066] In specific implementation, in this embodiment, before performing the state evaluation, the aged battery to be evaluated needs to be tested under different working conditions to obtain corresponding test data. Specifically, the tests under different working conditions in this embodiment include constant current charging conditions, constant voltage charging conditions, and constant current discharging conditions. For the constant current charging condition, for example, at room temperature, the battery sample is charged at a constant current of 0.5C until the charging cut-off voltage V1. For the constant voltage charging condition, for example, it continues to be charged under constant voltage conditions until the current drops below 0.02A, and then stands for 30 minutes. For the constant current discharging condition, for example, under the same room temperature conditions, the static battery sample is discharged at a constant current of 1C until the voltage is V3 = (V1 + V2) / 2, and the voltage-time curve and voltage-capacity curve of this experimental process are recorded. Among them, V1 is the charging cut-off voltage, and V2 is the discharging cut-off voltage.

[0067] Step S20: Calculate corresponding eigenvalues according to the current test data.

[0068] In specific implementation, according to the test data obtained from the tests, eigenvalue calculation can be performed. The eigenvalues in this embodiment include four eigenvalues, namely the first eigenvalue, the second eigenvalue, the third eigenvalue, and the fourth eigenvalue. When calculating the first eigenvalue, the time taken for the aged battery to be evaluated to rise from the first preset voltage to the charging cut-off voltage needs to be obtained from the current test data, and the first eigenvalue is determined according to this time. For example, assume that the first preset voltage is V4 and the charging cut-off voltage is V1, where V4 = V1 - 0.4. The time taken for the battery to be constantly charged from the V4 voltage to V1 is the first eigenvalue, and this first eigenvalue represents the charging time under the constant current charging condition.

[0069] Further, when calculating the second eigenvalue, it is necessary to obtain the voltage at a preset moment before reaching the charging cut-off voltage from the current test data, and determine the second eigenvalue according to the voltage at the preset moment before reaching the charging cut-off voltage. The second eigenvalue is the difference between the voltage at the preset moment before reaching the charging cut-off voltage and the charging cut-off voltage. For example, assume that the charging cut-off voltage is V1, the preset moment is 600 s, and the voltage at the preset moment before reaching the charging cut-off voltage is V5. The voltage increase from V5 to V1 during constant current charging, that is, V1 - V5, is the voltage increase and also the second eigenvalue.

[0070] Further, when calculating the third eigenvalue, it is necessary to obtain the time taken for the aging battery to be evaluated to discharge from the second preset voltage to the third preset voltage at a constant current from the current test data, and determine the third eigenvalue according to the time taken. The third eigenvalue represents the discharge duration. The second preset voltage and the third preset voltage are determined by the voltages after discharging at a constant current of 1C, and the second preset voltage is greater than the third preset voltage. The voltages after discharging at a constant current of 1C are determined by the charging cut-off voltage and the discharging cut-off voltage obtained from the current test data. For example, assume that the voltage after discharging at a constant current of 1C is V3, the second preset voltage V6 is V3 + 0.15, and the third preset voltage V7 is V3 - 0.05. The time taken to discharge from voltage V6 to voltage V7 at a constant current is also the third eigenvalue.

[0071] Further, when calculating the fourth eigenvalue, it is necessary to obtain the capacity discharged from the fourth preset voltage to the fifth preset voltage from the test data, and determine the fourth eigenvalue according to the discharged capacity. The fourth preset voltage and the fifth preset voltage are determined by the charging cut-off voltage, and the fourth preset voltage is greater than the fifth preset voltage. For example, assume that the charging cut-off voltage is V1, the fourth preset voltage V8 is V1 - 0.2, and the fifth preset voltage V9 is V1 - 0.3. The capacity discharged from voltage V8 to voltage V9 at a constant current is the fourth eigenvalue.

[0072] Step S30: Substitute the calculated eigenvalues into the constructed regression model to obtain the current electrochemical performance index and the current thermal safety risk index corresponding to the aging battery to be evaluated.

[0073] It should be noted that after calculating the above four eigenvalues, substituting the four eigenvalues into the constructed regression model can obtain the current electrochemical performance index and the current thermal safety risk index corresponding to the aging battery to be evaluated. For example, I1 = , where F1, F2, F3, and F4 are the first eigenvalue, the second eigenvalue, the third eigenvalue, and the fourth eigenvalue respectively, and I1 and I2 are the current electrochemical performance index and the current thermal safety risk index.

[0074] In some embodiments, the process of constructing the regression model is to collect the parameter information of multiple different aged battery cells of the same specification; conduct standard capacity tests and thermal runaway tests on multiple different aged battery cells and calculate the electrochemical performance index and thermal safety risk index based on the parameter information; obtain the historical test data of multiple different aged battery cells under different working conditions, and calculate the characteristic values according to the historical test data.

[0075] It should be noted that through the standard capacity test, the standard capacity can be obtained, while the rated capacity, charge cut-off voltage, and discharge cut-off voltage can be obtained from the collected parameter information. The electrochemical performance index can be calculated based on the standard capacity and the rated capacity, and the calculation formula is , where is the electrochemical performance index I1, Q is the standard capacity obtained through the standard capacity test, is the rated capacity. Further, through the thermal runaway experiment, the self-heating temperature of the battery, the thermal runaway trigger temperature, and the trigger time interval from the self-heating of the battery to thermal runaway can be obtained. The thermal safety risk index can be calculated based on the self-heating temperature of the battery, the thermal runaway trigger temperature, and the trigger time interval, and the calculation formula is , where T1 represents the self-heating temperature of the battery, T2 represents the thermal runaway trigger temperature, represents the trigger time interval from the self-heating of the battery to thermal runaway, is the thermal safety risk index.

[0076] In this embodiment, the temperature curve of the thermal runaway experiment can refer to Figure 2 shown, Figure 2 Taking a certain 40Ah ternary battery cell as an example, the temperature-time curve of its thermal runaway experiment is made in Figure 2 where T1, T2, and T3 respectively represent the self-heating temperature of the battery, the thermal runaway trigger temperature, and the maximum thermal runaway temperature; t1 and t2 respectively represent the time from the start of self-heating to the self-heating temperature and thermal runaway trigger temperature of the battery, and ∆t represents the time interval from the start of self-heating of the battery to the thermal runaway trigger time. It can be known that the lower the heating rate within the ∆t time interval, the lower the thermal safety risk of the battery.

[0077] Then, the tests and calculations of the characteristic values are carried out in the same way as above, which will not be elaborated here. Finally, a regression model with the expression I1 = , is constructed. The regression model in this embodiment can be extended to a support vector machine and a machine learning model.

[0078] Furthermore, in this embodiment, the correlations between 4 characteristic values (F1, F2, F3, F4) and the battery electrochemical performance I1 and the thermal safety risk index I2 are proved in sequence.

[0079] The relationships between F1, F2 and the degree of battery aging are as follows:

[0080] According to the above experimental method, non-destructive electrical performance tests were carried out on a batch of 40Ah ternary batteries with different aging degrees and different initial state of charge, and the voltage-time curves under constant current charging conditions were recorded. Due to the different initial state of charge of the battery samples, the time for the battery to reach the charging cut-off voltage V1 under constant current charging is different. For the convenience of comparison, the time to reach the charging cut-off voltage V1 is used as the reference time, and the "voltage-time" curves of different batteries are collectively translated. The schematic diagrams are shown in Figures 3(a)-(b). According to the definition of F1, starting from the voltage V4 (V4 = V1 - 0.4), the time taken for the battery to continue constant current charging to reach the charging cut-off voltage V1 is used as the characteristic value equal voltage charging time (F1). As shown in Figure 3(a), it can be seen that as the battery ages, F1 gradually increases. Similarly, according to the definition of F2 in Table 1, the terminal voltage in the 600s before the charging cut-off voltage V1 is denoted as V5, and the voltage increase from V5 to V1 under constant current charging is used as the characteristic value equal time voltage increase (F2). As shown in Figure 3(b), it can be seen that as the battery ages, F2 gradually decreases. Therefore, as the degree of battery aging deepens, the maximum available capacity of the battery decreases, and the corresponding F1 increases and the F2 characteristic value decreases, where u1 and u2 represent voltages respectively.

[0081] The relationships between F3, F4 and the degree of battery aging are as follows:

[0082] Similarly, the voltage-time curves and voltage-capacity curves under constant current discharging conditions were recorded, as shown in Figures 4(a)-(b). According to the definition of F3, starting from the voltage V6 (V6 = ), the time taken for the battery to continue constant current discharging to the voltage V7 (V7 = )is defined as the equal voltage discharging time (F3). As shown in Figure 4(a), it can be seen that as the battery ages, F3 gradually decreases. Similarly, according to the definition of F4 in Table 1, the capacity discharged from the voltage V8 (V8 = V1 - 0.2) to the voltage V9 (V9 = V1 - 0.3) of the battery is the equal voltage discharging capacity (F4). As shown in Figure 4(b), it can be seen that as the battery ages, F4 gradually decreases. Therefore, as the degree of battery aging deepens, the maximum available capacity of the battery decreases, and the corresponding F3 and F4 characteristic values decrease, where q1 and q2 represent capacities respectively.

[0083] Quantitatively calculate the correlations between the four characteristic values and the battery electrochemical performance I1 and the thermal safety risk index I2

[0084] To quantitatively prove the correlation between the four eigenvalues and the battery's electrochemical performance and thermal safety risk indicators, ten batteries of two systems, ternary and lithium iron phosphate, with different aging degrees were respectively subjected to standard capacity testing, short-time charge and discharge experiments, and battery thermal runaway tests in sequence according to the experimental procedures in Chapter 1. The values of the four eigenvalues (F1~F4), electrochemical performance, and thermal safety risk indicators (I1 and I2) are shown in Table 1. It can be seen from the table that as the battery aging degree deepens, the battery's electrochemical performance decreases and the thermal safety risk increases. Correspondingly, F1 increases, and the eigenvalues of F2, F3, and F4 decrease.

[0085] Table 1:

[0086]

[0087] The linear relationship between the eigenvalues and the electrochemical performance and thermal safety risk indicators was quantitatively characterized using the person correlation coefficient, as shown in Table 2. It can be seen that the absolute value of the person correlation coefficient between the four eigenvalues and the electrochemical performance and thermal safety risk indicators is greater than 0.9, indicating a strong linear correlation between the eigenvalues and the indicators.

[0088] Table 2:

[0089]

[0090] Step S40: Perform a state assessment on the to-be-evaluated aged battery based on the current electrochemical performance index and the current thermal safety risk index.

[0091] In a specific implementation, after obtaining the current electrochemical performance index and the current thermal safety risk index, substitute them into the calculation formula to obtain the comprehensive score of the battery state. Among them, R represents the comprehensive score of the battery state, and are the calculation results of the electrochemical performance index and the thermal safety risk index respectively. A and B are the respective weights corresponding to the electrochemical performance index and the thermal safety risk index. A and B can be set to 0.5 respectively, or can be adjusted according to the actual scenario. This embodiment does not limit this.

[0092] In this embodiment, the comprehensive evaluation score standard of the battery state can be referred to as shown in Table 3.

[0093] Table 3:

[0094]

[0095] In this embodiment, parameter information of multiple different aged battery cells of the same specification is collected; standard capacity tests and thermal runaway tests are performed on the multiple different aged battery cells, and electrochemical performance indicators and thermal safety risk indicators are calculated based on the parameter information; historical test data of the multiple different aged battery cells under different working conditions are obtained, and characteristic values are calculated according to the historical test data; a regression model of the electrochemical performance indicators, the thermal safety risk indicators and the characteristic values is constructed. In this way, through simple electrical performance experiments, an evaluation model of the characteristic values, the battery electrochemical performance and the thermal safety risk can be established, and finally a non-destructive, fast and comprehensive evaluation of the state of the aged battery can be achieved.

[0096] Refer to Figure 5 , Figure 5 FIG. is a structural block diagram of the first embodiment of the aged battery state evaluation system based on thermal safety according to the present invention.

[0097] As Figure 5 shown, the aged battery state evaluation system based on thermal safety proposed in the embodiment of the present invention includes:

[0098] A collection module 10, configured to perform tests on the aged battery to be evaluated under different working conditions in sequence to obtain current test data;

[0099] A processing module 20, configured to calculate corresponding characteristic values according to the current test data;

[0100] The processing module 20 is configured to substitute the calculated characteristic values into the constructed regression model to obtain the current electrochemical performance indicator and the current thermal safety risk indicator corresponding to the aged battery to be evaluated;

[0101] An evaluation module 30, configured to perform state evaluation on the aged battery to be evaluated based on the current electrochemical performance indicator and the current thermal safety risk indicator.

[0102] In this embodiment, parameter information of multiple different aged battery cells of the same specification is collected; standard capacity tests and thermal runaway tests are performed on the multiple different aged battery cells, and electrochemical performance indicators and thermal safety risk indicators are calculated based on the parameter information; historical test data of the multiple different aged battery cells under different working conditions are obtained, and characteristic values are calculated according to the historical test data; a regression model of the electrochemical performance indicators, the thermal safety risk indicators and the characteristic values is constructed. In this way, through simple electrical performance experiments, an evaluation model of the characteristic values, the battery electrochemical performance and the thermal safety risk can be established, and finally a non-destructive, fast and comprehensive evaluation of the state of the aged battery can be achieved.

[0103] In some embodiments, the system further includes a construction module;

[0104] The building block is used to collect parameter information of multiple different aged battery cells of the same specification;

[0105] Perform standard capacity tests and thermal runaway tests on multiple different aged battery cells and calculate electrochemical performance indicators and thermal safety risk indicators based on the parameter information;

[0106] Obtain historical test data of multiple different aged battery cells under different working conditions and calculate characteristic values according to the historical test data;

[0107] Construct a regression model of the electrochemical performance indicator, the thermal safety risk indicator and the characteristic value.

[0108] In some embodiments, the processing module 20 is used to obtain the standard capacity through a standard capacity test;

[0109] Determine the rated capacity based on the parameter information;

[0110] Calculate the electrochemical performance indicator according to the standard capacity and the rated capacity;

[0111] Obtain the self-heating temperature of the battery, the thermal runaway trigger temperature and the trigger time interval from the self-heating of the battery to the thermal runaway through a thermal runaway test;

[0112] Calculate the thermal safety risk indicator according to the self-heating temperature of the battery, the thermal runaway trigger temperature and the trigger time interval.

[0113] In some embodiments, the processing module 20 is used to obtain the time taken for the aging battery to be evaluated to rise from a first preset voltage to a charging cut-off voltage from the current test data, and determine a first characteristic value according to the time, where the first characteristic value represents the charging duration;

[0114] Obtain the voltage at a preset moment before reaching the charging cut-off voltage from the current test data, and determine a second characteristic value according to the voltage at the preset moment before reaching the charging cut-off voltage, where the second characteristic value is the difference between the voltage at the preset moment before reaching the charging cut-off voltage and the charging cut-off voltage, representing the voltage rise amplitude under a constant current charging condition;

[0115] Obtain the time taken for the aging battery to be evaluated to discharge at a constant current from a second preset voltage to a third preset voltage from the current test data, and determine a third characteristic value according to the time, where the third characteristic value represents the discharge duration, the second preset voltage and the third preset voltage are determined by the voltage after discharging at a constant current of 1C and the second preset voltage is greater than the third preset voltage, and the voltage after discharging at a constant current of 1C is determined by the charging cut-off voltage and the discharging cut-off voltage obtained from the current test data;

[0116] Obtain the capacity released from the fourth preset voltage to the fifth preset voltage from the test data, and determine a fourth characteristic value according to the released capacity. The fourth preset voltage and the fifth preset voltage are determined by the charging cut-off voltage and the fourth preset voltage is greater than the fifth preset voltage.

[0117] In some embodiments, the evaluation module 30 is configured to calculate a state score of the to-be-evaluated aged battery according to the current electrochemical performance index and the current thermal safety risk index. The calculation formula is , where A and B are the respective weights corresponding to the electrochemical performance index and the thermal safety risk index, and are the current electrochemical performance index and the current thermal safety risk index respectively.

[0118] An embodiment of the present application further provides an aged battery state evaluation device based on thermal safety, including a processor, a communication interface, a memory, and a communication bus. Among them, the processor, the communication interface, and the memory complete communication with each other through the communication bus. The memory is used to store an aged battery state evaluation program based on thermal safety; the processor is configured to implement the above-mentioned aged battery state evaluation method based on thermal safety when executing the program stored on the memory.

[0119] The communication bus mentioned in the above-mentioned aged battery state evaluation device based on thermal safety may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into an address bus, a data bus, a control bus, etc.

[0120] The communication interface is used for communication between the above-mentioned aged battery state evaluation device and other devices.

[0121] The memory may include a Random Access Memory (RAM), and may also include a Non-Volatile Memory (NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located far from the aforementioned processor.

[0122] The above-mentioned processor may be a general-purpose processor, including a central processing unit (abbreviation: CPU for short), a network processor (abbreviation: NP for short), etc.; it may also be a digital signal processor (abbreviation: DSP for short), an application-specific integrated circuit (abbreviation: ASIC for short), a field-programmable gate array (abbreviation: FPGA for short), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0123] In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wirelessly (such as infrared, wireless, microwave, etc.). The computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that includes one or more integrated available media. The available medium may be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a solid state disk (SSD)).

[0124] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

[0125] Each embodiment in this specification is described in a related manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and reference can be made to the relevant part of the method embodiment for the related content.

[0126] The above embodiments are only used to illustrate the technical solutions of the present invention, not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

[0127] It should be understood that the above is only for illustration and does not constitute any limitation to the technical solutions of the present invention. In specific applications, those skilled in the art can set according to needs, and the present invention does not make any restrictions in this regard.

[0128] It should be noted that the above-described work process is only illustrative and does not limit the protection scope of the present invention. In actual applications, those skilled in the art can select some or all of them according to actual needs to achieve the purpose of the solution of this embodiment, and no restrictions are made here.

[0129] In addition, for the technical details not described in detail in this embodiment, reference can be made to the method for evaluating the state of an aged battery based on thermal safety provided in any embodiment of the present invention, and details will not be repeated here.

[0130] In addition, it should be noted that in this text, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, such that a process, method, article or system comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or system. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of additional identical elements in the process, method, article or system comprising such element.

[0131] The serial numbers of the above-described embodiments of the present invention are only for description and do not represent the superiority or inferiority of the embodiments.

[0132] From the description of the above embodiments, those skilled in the art can clearly understand that the above-described embodiment methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation. Based on such an understanding, the technical solution of the present invention, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as Read Only Memory (ROM) / RAM, magnetic disk, optical disk) and includes several instructions for causing a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0133] The above are only the preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, is equally included in the patent protection scope of the present invention.

[0134] It can be understood that the system provided by the embodiments of the present invention corresponds to the method provided by the embodiments of the present invention. The explanations, examples and beneficial effects of the relevant content can refer to the corresponding parts in the above method.

Claims

1. An aging battery state evaluation method based on thermal safety, characterized in that The aging battery state evaluation method based on thermal safety includes: Performing tests on the aging battery to be evaluated under different working conditions in sequence to obtain current test data; Calculating corresponding characteristic values according to the current test data; Among them, the calculating corresponding characteristic values according to the current test data includes: Obtaining the time taken for the aging battery to be evaluated to rise from a first preset voltage to the charging cut-off voltage from the current test data, and determining a first characteristic value according to the time, where the first characteristic value represents the charging duration; Obtaining the voltage at a preset moment before reaching the charging cut-off voltage from the current test data, and determining a second characteristic value according to the voltage at the preset moment before reaching the charging cut-off voltage, where the second characteristic value is the difference between the voltage at the preset moment before reaching the charging cut-off voltage and the charging cut-off voltage, representing the voltage rise amplitude under the constant current charging condition; Obtaining the time taken for the aging battery to be evaluated to discharge at a constant current from a second preset voltage to a third preset voltage from the current test data, and determining a third characteristic value according to the time, where the third characteristic value represents the discharge duration, and the second preset voltage and the third preset voltage are determined by the voltage after discharging at a constant current of 1C and the second preset voltage is greater than the third preset voltage, and the voltage after discharging at a constant current of 1C is determined by the charging cut-off voltage and the discharge cut-off voltage obtained from the current test data; Obtaining the capacity discharged from a fourth preset voltage to a fifth preset voltage from the test data, and determining a fourth characteristic value according to the discharged capacity, where the fourth preset voltage and the fifth preset voltage are determined by the charging cut-off voltage and the fourth preset voltage is greater than the fifth preset voltage; Substituting the calculated characteristic values into the constructed regression model to obtain the current electrochemical performance index and the current thermal safety risk index corresponding to the aging battery to be evaluated; Performing state evaluation on the aging battery to be evaluated based on the current electrochemical performance index and the current thermal safety risk index; Among them, the performing state evaluation on the aging battery to be evaluated based on the current electrochemical performance index and the current thermal safety risk index includes: Calculate the state score of the battery to be evaluated for aging according to the current electrochemical performance index and the current thermal safety risk index. The calculation formula is , where A and B are the weights corresponding to the electrochemical performance index and the thermal safety risk index respectively, and are the current electrochemical performance index and the current thermal safety risk index respectively.

2. The method for evaluating the state of an aged battery based on thermal safety according to claim 1, wherein, The method further includes: Collecting parameter information of multiple different aging battery cells of the same specification; Performing standard capacity tests and thermal runaway tests on multiple different aging battery cells and calculating the electrochemical performance index and the thermal safety risk index based on the parameter information; Obtaining historical test data of multiple different aging battery cells under different working conditions, and calculating characteristic values according to the historical test data; Constructing a regression model of the electrochemical performance index, the thermal safety risk index and the characteristic values.

3. The method for evaluating the state of an aged battery based on thermal safety according to claim 2, wherein, The performing standard capacity tests and thermal runaway tests on multiple different aging battery cells and calculating the electrochemical performance index and the thermal safety risk index based on the parameter information includes: Obtaining the standard capacity through a standard capacity test; Determining the rated capacity based on the parameter information; Calculating the electrochemical performance index according to the standard capacity and the rated capacity; Obtain the self-generated heat temperature of the battery, the thermal runaway trigger temperature, and the trigger time interval from the self-generated heat of the battery to thermal runaway through thermal runaway tests; Calculate the thermal safety risk index based on the self-generated heat temperature of the battery, the thermal runaway trigger temperature, and the trigger time interval.

4. An aging battery state evaluation system based on thermal safety, characterized in that, The aging battery state evaluation system based on thermal safety includes: An acquisition module for sequentially testing the aging battery to be evaluated under different working conditions to obtain current test data; A processing module for calculating corresponding characteristic values according to the current test data; Wherein, the processing module is further configured to obtain the time taken for the aging battery to be evaluated to rise from a first preset voltage to the charging cut-off voltage from the current test data, and determine a first characteristic value according to the time, and the first characteristic value represents the charging duration; Obtain the voltage at a preset moment before reaching the charging cut-off voltage from the current test data, and determine a second characteristic value according to the voltage at the preset moment before reaching the charging cut-off voltage, and the second characteristic value is the difference between the voltage at the preset moment before reaching the charging cut-off voltage and the charging cut-off voltage, representing the voltage rise amplitude under the constant current charging condition; Obtain the time taken for the aging battery to be evaluated to discharge at a constant current from a second preset voltage to a third preset voltage from the current test data, and determine a third characteristic value according to the time, and the third characteristic value represents the discharge duration, and the second preset voltage and the third preset voltage are determined by the voltage after discharging at a constant current of 1C and the second preset voltage is greater than the third preset voltage, and the voltage after discharging at a constant current of 1C is determined by the charging cut-off voltage and the discharging cut-off voltage obtained from the current test data; Obtain the capacity discharged from a fourth preset voltage to a fifth preset voltage from the test data, and determine a fourth characteristic value according to the discharged capacity, and the fourth preset voltage and the fifth preset voltage are determined by the charging cut-off voltage and the fourth preset voltage is greater than the fifth preset voltage; The processing module is configured to substitute the calculated characteristic values into the constructed regression model to obtain the current electrochemical performance index and the current thermal safety risk index corresponding to the aging battery to be evaluated; An evaluation module for performing state evaluation on the aging battery to be evaluated based on the current electrochemical performance index and the current thermal safety risk index; Among them, the evaluation module is further configured to calculate a state score of the battery to be evaluated for aging according to the current electrochemical performance index and the current thermal safety risk index, and the calculation formula is , where A and B are the weights corresponding to the electrochemical performance index and the thermal safety risk index respectively, and are the current electrochemical performance index and the current thermal safety risk index respectively.

5. The aging battery state evaluation system based on thermal safety as described in claim 4, wherein The system further includes a construction module; The construction module is configured to collect parameter information of multiple different aging battery cells of the same specification; Perform standard capacity tests and thermal runaway tests on multiple different aging battery cells and calculate electrochemical performance indexes and thermal safety risk indexes based on the parameter information; Obtain historical test data of multiple different aging battery cells under different working conditions, and calculate characteristic values according to the historical test data; Construct a regression model of the electrochemical performance index, the thermal safety risk index and the characteristic values.

6. The aging battery state evaluation system based on thermal safety according to claim 5, characterized in that, The processing module is configured to obtain the standard capacity through a standard capacity test; Determine the rated capacity based on the parameter information; Calculate the electrochemical performance index according to the standard capacity and the rated capacity; Obtain the self-generated heat temperature of the battery, the thermal runaway trigger temperature, and the trigger time interval from the self-generated heat of the battery to thermal runaway through thermal runaway tests; Calculate the thermal safety risk index based on the self-generated heat temperature of the battery, the thermal runaway trigger temperature, and the trigger time interval.

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