Detection methods, detection devices, and computer-readable storage media

Abstract

This application provides a detection method, a detection device, and a computer-readable storage medium. In this method, a first model is determined based on the self-discharge effect of a battery cell based on chemical reactions, and a second model is determined based on both the self-discharge effect of the battery cell based on chemical reactions and the self-discharge effect based on physical factors. The first model outputs a first open-circuit voltage value corresponding to a first resting time of the first battery cell, and the second model outputs a second open-circuit voltage value corresponding to the first resting time. The safety level of the first battery cell is determined based on the difference between the first and second open-circuit voltage values. For example, if the absolute value of the difference is 0, it indicates that the first battery cell does not have a physical internal short circuit, which means that the safety level of the first battery cell is high; if the absolute value of the difference is greater than 0, it indicates that the first battery cell has a physical internal short circuit, which means that the safety level of the first battery cell is low.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a detection method, a detection device, and a computer-readable storage medium. Background Technology

[0002] With the development of new energy technologies, batteries are being used in a wider range of fields, such as as a power source to power vehicles, in order to reduce the use of non-renewable resources.

[0003] After batteries roll off the production line, they take a considerable amount of time to reach the customer. For various reasons, customers may not use the batteries immediately upon receipt, but instead leave them idle. These batteries consist of multiple individual cells. During this extended period of inactivity, the safety level of each individual cell can change, affecting the customer's ability to use the battery. Therefore, determining the safety level of individual cells after prolonged inactivity is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] This application provides a testing method, a testing device, and a computer-readable storage medium that can support the determination of the safety level of a battery cell after long-term static storage.

[0005] In a first aspect, a detection method is provided, comprising: inputting a first resting time of a first battery cell into a first model to obtain and output a first open circuit voltage (OCV) value corresponding to the first resting time, wherein the first model is determined based on the self-discharge effect of the first battery cell based on chemical reaction; inputting the first resting time into a second model to obtain and output a second open circuit voltage value corresponding to the first resting time, wherein the second model is determined based on the self-discharge effect of the first battery cell based on chemical reaction and the self-discharge effect based on physical factors; and determining the safety level of the first battery cell based on the absolute value of the difference between the first open circuit voltage value and the second open circuit voltage value.

[0006] By inputting the first resting time of the first battery cell into a first model and a second model, respectively, the first model is determined based on the self-discharge effect of the first battery cell based on chemical reactions, and the second model is determined based on the self-discharge effect of the first battery cell based on both chemical reactions and physical factors. The first model outputs a first open-circuit voltage value corresponding to the first resting time, and the second model outputs a second open-circuit voltage value corresponding to the first resting time. The safety level of the first battery cell can be determined by the absolute value of the difference between the first and second open-circuit voltage values. For example, if the absolute value of the difference between the first and second open-circuit voltage values ​​is 0, it indicates that there is no physical internal short circuit in the first battery cell, or that the size of the metal particles inside the first battery cell is small, which indicates a high safety level for the first battery cell. If the absolute value of the difference between the first and second open-circuit voltage values ​​is greater than 0, it indicates that there is a physical internal short circuit in the first battery cell, or that the size of the metal particles inside the first battery cell is large, which indicates a low safety level for the first battery cell.

[0007] Specifically, since the first model is determined based on the self-discharge effect of the first battery cell based on chemical reactions, the open-circuit voltage value output by the first model can reflect the self-discharge effect of the first battery cell based on chemical reactions. The second model is determined based on the self-discharge effect of the first battery cell based on both chemical reactions and physical factors. The open-circuit voltage value output by the second model can reflect the self-discharge effect of the first battery cell based on both chemical reactions and physical factors. If the open-circuit voltage value output by the first model is the same as that output by the second model, it means that the self-discharge effect of the first battery cell is based on chemical reactions, not physical factors. If the open-circuit voltage value output by the first model is different from that output by the second model, it means that the first battery cell has both self-discharge effects based on chemical reactions and physical factors. Thus, the safety level of the first battery cell after long-term static storage can be determined by comparing the absolute value of the difference between the open-circuit voltage values ​​output by the first model and the second model.

[0008] Furthermore, since both the first model and the second model are related to the first battery cell, the absolute value of the difference between the open-circuit voltage values ​​output by the first model and the second model can be used to determine the safety level of the first battery cell. This method can be applied to determine the safety level of other battery cells. For example, Model 1 can be determined based on the chemical reaction-based self-discharge effect of the second battery cell, and Model 2 can be determined based on both the chemical reaction-based and physical factor-based self-discharge effects of the second battery cell. The safety level of the second battery cell can then be determined based on the absolute value of the difference between the open-circuit voltage values ​​output by Model 1 and Model 2. Alternatively, different battery cells can correspond to different first and second models. Given the same resting time for these different battery cells, the corresponding first and second models will differ, and the absolute values ​​of the differences in their corresponding open-circuit voltage values ​​will also differ, thus enabling the determination of the safety level of different battery cells.

[0009] One possible implementation is that, as described above, determining the safety level of the first battery cell based on the absolute value of the difference between the first open-circuit voltage value and the second open-circuit voltage value includes: determining the safety level of the first battery cell based on the absolute value of the difference between the first open-circuit voltage value and the second open-circuit voltage value and a preset threshold.

[0010] By setting a preset threshold, the safety level of the first battery cell can be determined more accurately. For example, if the absolute value of the difference between the first open-circuit voltage value and the second open-circuit voltage value is less than the preset threshold, the safety level of the first battery cell is at level one. If the absolute value of the difference between the first open-circuit voltage value and the second open-circuit voltage value is greater than or equal to the preset threshold, the safety level of the first battery cell is at level two. Level one is higher than level two, which means that the safety level of the first battery cell at level one is higher than that of the first battery cell at level two.

[0011] One possible implementation is that the first model is obtained by training the model based on multiple resting times of the first battery cell, multiple open-circuit voltage values ​​of the first battery cell, and the self-discharge effect of the first battery cell based on chemical reactions. The second model is obtained by training the model based on multiple resting times of the first battery cell, multiple open-circuit voltage values ​​of the first battery cell, and the self-discharge effect of the first battery cell based on chemical reactions and the self-discharge effect based on physical factors. The multiple open-circuit voltage values ​​of the first battery cell and the multiple resting times of the first battery cell correspond one-to-one.

[0012] The above approach improves the reliability of the open-circuit voltage values ​​output by the models. Specifically, since both the first and second models are determined through training based on multiple resting times and multiple open-circuit voltage values ​​of the first battery cell, both models can be used to predict the open-circuit voltage values ​​of the first battery cell after long-term resting. Furthermore, this also improves the reliability of assessing the safety level of the first battery cell. Specifically, the first model can predict the open-circuit voltage values ​​of the first battery cell under the self-discharge effect based on chemical reactions, while the second model can predict the open-circuit voltage values ​​of the first battery cell under both the self-discharge effect based on chemical reactions and the self-discharge effect based on physical factors. For the same resting time, when the open-circuit voltage values ​​output by the first and second models are the same, it indicates that the first battery cell exhibits a self-discharge effect based on chemical reactions. If the open-circuit voltage values ​​output by the first and second models are different, it indicates that the first battery cell exhibits both self-discharge effects based on chemical reactions and self-discharge effects based on physical factors.

[0013] One possible implementation involves a first model whose parameters include a first coefficient, a second coefficient, and a third coefficient, all of which are related to the self-discharge effect of the battery cell based on chemical reactions. This model allows for the prediction of the open-circuit voltage of battery cells exhibiting self-discharge due to chemical reactions.

[0014] One possible implementation, the first model satisfies: V is the open-circuit voltage value, where a1 is the first coefficient, b1 is the second coefficient, c1 is the third coefficient, t represents the resting time, and e represents the natural constant (its value is approximately 2.71828). This model supports the prediction of the open-circuit voltage output by the first model, which is relatively close to the actual open-circuit voltage value of the first battery cell; that is, the reliability of the open-circuit voltage prediction value output by the first model is high.

[0015] One possible implementation involves a second model whose parameters include a fourth, fifth, sixth, seventh, and eighth coefficient. The fourth, fifth, and sixth coefficients are related to the chemical reaction-based self-discharge effect of the battery cell, while the seventh and eighth coefficients are related to the physical factor-based self-discharge effect of the battery cell. This model allows for the prediction of the open-circuit voltage of battery cells exhibiting self-discharge effects due to both chemical reactions and physical factors.

[0016] One possible implementation, the second model satisfies: V is the open-circuit voltage value, a2 represents the fourth coefficient, b2 represents the fifth coefficient, c2 represents the sixth coefficient, d represents the seventh coefficient, f represents the eighth coefficient, t is the resting time of the battery cell, and e represents the natural constant.

[0017] Based on the above model, since both the seventh and eighth coefficients are related to the self-discharge effect of the battery cell based on physical factors, the second model can be applied to predict the open-circuit voltage of battery cells with physical internal short circuits.

[0018] Secondly, a detection device is provided, comprising: a processing unit for inputting a first resting time of a first battery cell into a first model, obtaining and outputting a first open-circuit voltage value corresponding to the first resting time, the first model being determined based on the self-discharge effect of the first battery cell based on chemical reactions; inputting the first resting time into a second model, obtaining and outputting a second open-circuit voltage value corresponding to the first resting time, the second model being determined based on the self-discharge effect of the first battery cell based on chemical reactions and the self-discharge effect based on physical factors; and determining the safety level of the first battery cell based on the absolute value of the difference between the first open-circuit voltage value and the second open-circuit voltage value.

[0019] For a description of the beneficial effects of the second aspect, please refer to the description of the beneficial effects of the first aspect.

[0020] One possible implementation is a processing unit configured to determine the safety level of a first battery cell based on the absolute value of the difference between a first open-circuit voltage value and a second open-circuit voltage value, comprising: determining the safety level of the first battery cell based on the absolute value of the difference between the first open-circuit voltage value and the second open-circuit voltage value and a preset threshold.

[0021] One possible implementation is that the first model is obtained by training the model based on multiple resting times of the first battery cell, multiple open-circuit voltage values ​​of the first battery cell, and the self-discharge effect of the first battery cell based on chemical reactions. The second model is obtained by training the model based on multiple resting times of the first battery cell, multiple open-circuit voltage values ​​of the first battery cell, and the self-discharge effect of the first battery cell based on chemical reactions and the self-discharge effect based on physical factors. The multiple open-circuit voltage values ​​of the first battery cell and the multiple resting times of the first battery cell correspond one-to-one.

[0022] One possible implementation is that the model parameters of the first model include a first coefficient, a second coefficient, and a third coefficient, all of which are related to the self-discharge effect of the battery cell based on chemical reaction.

[0023] One possible implementation, the first model satisfies: V is the open-circuit voltage value, where a1 is the first coefficient, b1 is the second coefficient, c1 is the third coefficient, t represents the resting time, and e represents the natural constant.

[0024] One possible implementation is that the model parameters of the second model include a fourth coefficient, a fifth coefficient, a sixth coefficient, a seventh coefficient, and an eighth coefficient. The fourth, fifth, and sixth coefficients are all related to the self-discharge effect of the battery cell based on chemical reactions, while the seventh and eighth coefficients are both related to the self-discharge effect of the battery cell based on physical factors.

[0025] One possible implementation, the second model satisfies: V is the open-circuit voltage value, a2 represents the fourth coefficient, b2 represents the fifth coefficient, c2 represents the sixth coefficient, d represents the seventh coefficient, f represents the eighth coefficient, t is the resting time of the battery cell, and e represents the natural constant.

[0026] Thirdly, a detection device is provided, the device including a processor and a memory, the memory for storing a computer program and the processor for calling the computer program to execute the methods in the first aspect or its various implementations.

[0027] Fourthly, a computer-readable storage medium is provided for storing a computer program that causes a computer to perform the methods described in the first aspect or its implementations. Attached Figure Description

[0028] Figure 1 This diagram illustrates an application scenario of the detection method according to an embodiment of this application.

[0029] Figure 2 A schematic flowchart of the detection method 200 according to an embodiment of this application is shown.

[0030] Figure 3 This diagram illustrates the training of the first model.

[0031] Figure 4 The diagram illustrates the relationship between the predicted open-circuit voltage output from the first model and the actual open-circuit voltage of the second cell.

[0032] Figure 5 This diagram illustrates a relationship between the predicted open-circuit voltage output by the second model and the actual open-circuit voltage of a battery cell with a physical internal short circuit.

[0033] Figure 6 This diagram illustrates the relationship between the predicted open-circuit voltage values ​​from different models and the actual open-circuit voltage values ​​of battery cells with physical internal short circuits.

[0034] Figure 7 A schematic diagram illustrating a relationship between the first model and the second model is shown.

[0035] Figure 8 A schematic diagram illustrating yet another relationship between the first model and the second model is shown.

[0036] Figure 9 A schematic diagram illustrating yet another relationship between the first and second models is shown.

[0037] Figure 10 A schematic diagram illustrating yet another relationship between the first and second models is shown.

[0038] Figure 11 A schematic diagram illustrating yet another relationship between the first and second models is shown.

[0039] Figure 12 A schematic diagram illustrating yet another relationship between the first and second models is shown.

[0040] Figure 13 A schematic block diagram of a detection device 1300 according to an embodiment of this application is shown.

[0041] Figure 14 A schematic diagram of the hardware structure of the detection device 1400 according to an embodiment of this application is shown. Detailed Implementation

[0042] The embodiments of this application are described below with reference to the accompanying drawings and examples. The following description and drawings of the embodiments are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0043] In the description of this application, unless otherwise stated, "a plurality of" means two or more. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having" and any variations thereof in the description, claims and foregoing drawings of this application are intended to cover non-exclusive inclusion.

[0045] In this application, the reference to "embodiment" means that a specific feature or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0046] As described in the background section, after a battery rolls off the production line, it remains in a static state until it is used. This static state can last for a considerable period, such as 3 months, 6 months, 12 months, 18 months, or even longer. During this long-term static period, the safety level of the battery cell changes, affecting the customer's experience with the battery. For example, during the battery manufacturing process, some small metal particles may be present inside the battery cell. These small particles do not cause significant damage to the battery cell's safety and cannot be detected by the HIT-pot process. However, during long-term static storage, these metal particles can deposit, increasing their size. When the size of these particles exceeds a certain threshold, they can create a physical internal short circuit. This physical short circuit exacerbates the self-discharge effect of the battery cell and may even lead to thermal runaway during charging. Therefore, battery suppliers need to determine the safety level of battery cells after long-term static storage and provide customers with battery cells that meet their safety requirements.

[0047] Currently, there are no suitable methods to test the safety level of individual battery cells after long-term static storage. This means that the safety level of individual battery cells after long-term static storage is unknown, which may lead to potential risks.

[0048] In view of this, this application provides a detection method. A first resting time of a first battery cell is input into a first model and a second model. The first model is determined based on the self-discharge effect of the first battery cell based on chemical reactions, and the second model is determined based on both the self-discharge effect based on chemical reactions and the self-discharge effect based on physical factors. The first model outputs a first open-circuit voltage value corresponding to the first resting time, and the second model outputs a second open-circuit voltage value corresponding to the first resting time. The safety level of the first battery cell can be determined by the absolute value of the difference between the first and second open-circuit voltage values. For example, if the absolute value of the difference between the first and second open-circuit voltage values ​​is 0, it indicates that there is no physical internal short circuit within the first battery cell, or that the size of the metal particles inside the first battery cell is small, indicating a high safety level. If the absolute value of the difference between the first and second open-circuit voltage values ​​is greater than 0, it indicates that there is a physical internal short circuit within the first battery cell, or that the size of the metal particles inside the first battery cell is large, indicating a low safety level.

[0049] Specifically, since the first model is determined based on the self-discharge effect of the first battery cell based on chemical reactions, the open-circuit voltage value output by the first model can reflect the self-discharge effect of the first battery cell based on chemical reactions. The second model is determined based on the self-discharge effect of the first battery cell based on both chemical reactions and physical factors. The open-circuit voltage value output by the second model can reflect the self-discharge effect of the first battery cell based on both chemical reactions and physical factors. If the open-circuit voltage value output by the first model is the same as that output by the second model, it means that the self-discharge effect of the first battery cell is based on chemical reactions, not physical factors. If the open-circuit voltage value output by the first model is different from that output by the second model, it means that the first battery cell has both self-discharge effects based on chemical reactions and physical factors. Thus, the safety level of the first battery cell after long-term static storage can be determined by comparing the absolute value of the difference between the open-circuit voltage values ​​output by the first model and the second model.

[0050] Figure 1 This diagram illustrates an application scenario of the detection method according to an embodiment of this application. For example... Figure 1 As shown, after the battery unit comes off the production line, it undergoes long-distance transportation. Figure 1Taking transportation methods including automobiles as an example, but not limited to roll-on / roll-off ships, the battery device arrives at the customer's warehouse and is stored there. The aforementioned long-distance transportation can include domestic and / or overseas transportation, which can take a considerable amount of time, such as 3 months, 6 months, or even longer. Due to various reasons, the battery device may also be stored in the customer's warehouse for a long period, such as 6 months or 18 months.

[0051] A battery device may include at least one battery cell assembly for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or a combination of these cells via a busbar. A battery cell may be a rechargeable battery, meaning a battery cell that can be recharged after discharge to reactivate its active materials and continue to be used.

[0052] The battery cell can be a lithium-ion battery, lithium iron phosphate battery, nickel-cobalt-manganese ternary battery, nickel-cobalt-aluminum ternary battery, sodium-ion lithium battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, or negative electrodeless battery, etc., and there is no limitation on this. The type of battery cell can also be a stacked battery cell, a pouch battery cell, a prismatic battery cell, or a cylindrical battery cell, etc.

[0053] A battery cell assembly is typically formed by arranging multiple battery cells. As an example, a battery cell assembly is a battery module, which is formed by arranging and fixing multiple battery cells together to form a single module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0054] The battery device can also be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0055] Figure 2 A schematic flowchart of a detection method 200 according to an embodiment of this application is shown. Optionally, the execution entity of method 200 may be a detection device. Method 200 includes:

[0056] S210. Input the first resting time of the first battery cell into the first model, obtain and output the first open-circuit voltage value corresponding to the first resting time. The first model is determined based on the self-discharge effect of the first battery cell based on chemical reaction.

[0057] S220. Input the first resting time into the second model, obtain and output the second open-circuit voltage value corresponding to the first resting time. The second model is determined based on the self-discharge effect of the first battery cell based on chemical reaction and the self-discharge effect based on physical factors.

[0058] S230. Determine the safety level of the first battery cell based on the absolute value of the difference between the first open-circuit voltage value and the second open-circuit voltage value.

[0059] By inputting the first resting time of the first battery cell into a first model and a second model, respectively, the first model is determined based on the self-discharge effect of the first battery cell based on chemical reactions, and the second model is determined based on the self-discharge effect of the first battery cell based on both chemical reactions and physical factors. The first model outputs a first open-circuit voltage value corresponding to the first resting time, and the second model outputs a second open-circuit voltage value corresponding to the first resting time. The safety level of the first battery cell can be determined by the absolute value of the difference between the first and second open-circuit voltage values. For example, if the absolute value of the difference between the first and second open-circuit voltage values ​​is 0, it indicates that there is no physical internal short circuit in the first battery cell, or that the size of the metal particles inside the first battery cell is small, which indicates a high safety level for the first battery cell. If the absolute value of the difference between the first and second open-circuit voltage values ​​is greater than 0, it indicates that there is a physical internal short circuit in the first battery cell, or that the size of the metal particles inside the first battery cell is large, which indicates a low safety level for the first battery cell.

[0060] Specifically, since the first model is determined based on the self-discharge effect of the first battery cell based on chemical reactions, the open-circuit voltage value output by the first model can reflect the self-discharge effect of the first battery cell based on chemical reactions. The second model is determined based on the self-discharge effect of the first battery cell based on both chemical reactions and physical factors. The open-circuit voltage value output by the second model can reflect the self-discharge effect of the first battery cell based on both chemical reactions and physical factors. If the open-circuit voltage value output by the first model is the same as that output by the second model, it means that the self-discharge effect of the first battery cell is based on chemical reactions, not physical factors. If the open-circuit voltage value output by the first model is different from that output by the second model, it means that the first battery cell has both self-discharge effects based on chemical reactions and physical factors. Thus, the safety level of the first battery cell after long-term static storage can be determined by comparing the absolute value of the difference between the open-circuit voltage values ​​output by the first model and the second model.

[0061] Furthermore, since both the first model and the second model are related to the first battery cell, the absolute value of the difference between the open-circuit voltage values ​​output by the first model and the second model can be used to determine the safety level of the first battery cell. This method can be applied to determine the safety level of other battery cells. For example, Model 1 can be determined based on the chemical reaction-based self-discharge effect of the second battery cell, and Model 2 can be determined based on both the chemical reaction-based and physical factor-based self-discharge effects of the second battery cell. The safety level of the second battery cell can then be determined based on the absolute value of the difference between the open-circuit voltage values ​​output by Model 1 and Model 2. Alternatively, different battery cells can correspond to different first and second models. Given the same resting time for these different battery cells, the corresponding first and second models will differ, and the absolute values ​​of the differences in their corresponding open-circuit voltage values ​​will also differ, thus enabling the determination of the safety level of different battery cells.

[0062] The time unit for the first resting period is consistent with the time unit supported by the aforementioned model. For example, if the aforementioned model supports days as the time unit, then the time unit for the first resting period is days. For example, if the aforementioned model supports hours as the time unit, then the time unit for the first resting period is hours. For example, if the aforementioned model supports minutes as the time unit, then the time unit for the first resting period is minutes.

[0063] The first battery cell can be a battery cell in transit, a battery cell stored in a customer's warehouse, or a battery cell that has come off the production line but has not yet been assembled into a transport vehicle. Therefore, the settling time of the first battery cell is relative to the time it came off the production line. The settling time of the first battery cell can be more than 10 days, or it can be less than 10 days.

[0064] After the testing device inputs the first resting time of the first battery cell into the first model and the second model respectively, the first model and the second model obtain and output the open-circuit voltage value corresponding to the first resting time based on their internal reasoning processes. The testing device can directly display the safety level of the first battery cell to the customer, or it can output the safety level of the first battery cell to a display device, which in turn outputs the safety level of the first battery cell to the customer.

[0065] The first model is determined based on the self-discharge effect of the first battery cell based on chemical reactions. This can be understood as follows: the modeling of the first model is based on the self-discharge effect of the first battery cell based on chemical reactions, or the modeling of the first model references the self-discharge effect of the first battery cell based on chemical reactions. Specifically, the self-discharge effect of the first battery cell based on chemical reactions can be understood as follows: when the first battery cell is left stagnant for a long time, the electrolyte will undergo redox reactions on both the positive and negative electrode sides of the first battery cell, leading to the loss of active ions and a decrease in the open-circuit voltage of the first battery cell.

[0066] The second model is determined based on the self-discharge effects of the first battery cell based on chemical reactions and physical factors. This can be understood as follows: the modeling of the second model is based on the self-discharge effects of the first battery cell based on chemical reactions and physical factors, or the modeling of the second model references the self-discharge effects of the first battery cell based on chemical reactions and physical factors. The description of the self-discharge effect of the first battery cell based on chemical reactions can be found in the previous paragraph and will not be repeated here. The self-discharge effect of the first battery cell based on physical factors can be understood as follows: when the first battery cell is left undisturbed for a long time, tiny metal particles exist inside the electrodes of the first battery cell. These tiny metal particles will not pierce the separator between the positive and negative electrodes, but they will form a micro-short circuit, resulting in a decrease in the open-circuit voltage of the first battery cell.

[0067] One possible implementation, method 200, also includes:

[0068] The safety level of the first battery cell is determined based on the absolute value of the difference between the first open-circuit voltage value and the second open-circuit voltage value, as well as a preset threshold.

[0069] By setting a preset threshold, the safety level of the first battery cell can be determined more accurately. For example, if the absolute value of the difference between the first open-circuit voltage value and the second open-circuit voltage value is less than the preset threshold, the safety level of the first battery cell is at level one. If the absolute value of the difference between the first open-circuit voltage value and the second open-circuit voltage value is greater than or equal to the preset threshold, the safety level of the first battery cell is at level two. Level one is higher than level two, which means that the safety level of the first battery cell at level one is higher than that of the first battery cell at level two.

[0070] Specifically, the preset threshold can be a threshold configured based on the experience of using individual battery cells, or a threshold set based on the safe operating status of individual battery cells; there is no limitation on this.

[0071] For example, the preset threshold is equal to the product of 0.005 mv / day and the resting time of the battery cell.

[0072] For example, the preset threshold is equal to the product of 0.01 mv / day and the resting time of the battery cell.

[0073] For example, the preset threshold is equal to the product of 0.02 mv / day and the resting time of the battery cell.

[0074] One possible implementation is that the first model is obtained by training the model based on multiple resting times of the first battery cell, multiple open-circuit voltage values ​​of the first battery cell, and the self-discharge effect of the first battery cell based on chemical reactions. The second model is obtained by training the model based on multiple resting times of the first battery cell, multiple open-circuit voltage values ​​of the first battery cell, and the self-discharge effect of the first battery cell based on chemical reactions and the self-discharge effect based on physical factors. The multiple open-circuit voltage values ​​of the first battery cell and the multiple resting times of the first battery cell correspond one-to-one.

[0075] The above approach improves the reliability of the open-circuit voltage values ​​output by the models. Specifically, since both the first and second models are determined through training based on multiple resting times and multiple open-circuit voltage values ​​of the first battery cell, both models can be used to predict the open-circuit voltage values ​​of the first battery cell after long-term resting. Furthermore, this also improves the reliability of assessing the safety level of the first battery cell. Specifically, the first model can predict the open-circuit voltage values ​​of the first battery cell under the self-discharge effect based on chemical reactions, while the second model can predict the open-circuit voltage values ​​of the first battery cell under both the self-discharge effect based on chemical reactions and the self-discharge effect based on physical factors. For the same resting time, when the open-circuit voltage values ​​output by the first and second models are the same, it indicates that the first battery cell exhibits a self-discharge effect based on chemical reactions. If the open-circuit voltage values ​​output by the first and second models are different, it indicates that the first battery cell exhibits both self-discharge effects based on chemical reactions and self-discharge effects based on physical factors.

[0076] The multiple open-circuit voltage values ​​of a first battery cell correspond one-to-one with multiple resting times of the first battery cell. This can be understood as follows: one open-circuit voltage value of a first battery cell corresponds to one resting time of the first battery cell. Alternatively, multiple open-circuit voltage values ​​of a first battery cell can also correspond to the same resting time of the first battery cell. For example, when the resting time of the first battery cell is in days, the open-circuit voltage of the first battery cell can be measured multiple times within a certain test date, obtaining multiple open-circuit voltage values, which correspond to that test date. Similarly, when the resting time of the first battery cell is in hours, the open-circuit voltage of the first battery cell can be measured multiple times within a certain test hour, obtaining multiple open-circuit voltage values, which correspond to that test hour.

[0077] One possible example is that if the resting time of the first battery cell is in days, then the resting time of the first battery cell corresponds to the open-circuit voltage value of the first battery cell.

[0078] One possible example is that the lower limit and upper limit of the time range corresponding to the multiple resting times of the first battery cell are 0 days and 30 days, respectively.

[0079] Optionally, the first model is obtained by training the model based on multiple resting times of the second battery cell, multiple open-circuit voltage values ​​of the second battery cell, and the self-discharge effect of the battery cell based on chemical reactions. The second model is obtained by training the model based on multiple resting times of the second battery cell, multiple open-circuit voltage values ​​of the second battery cell, and the self-discharge effect of the battery cell based on chemical reactions and the self-discharge effect based on physical factors. The multiple open-circuit voltage values ​​of the second battery cell correspond one-to-one with the multiple resting times of the second battery cell.

[0080] The first and second battery cells can possess the same characteristics. For example, the first and second battery cells may be produced in the same batch, or they may be of the same type, such as both being pouch cells. Alternatively, the constituent materials of the first and second battery cells may be the same. The constituent materials of the battery cells include, but are not limited to, negative electrode materials, positive electrode materials, electrolytes, and separators. When the first and second battery cells possess the same characteristics, the model obtained based on the resting time and open-circuit voltage values ​​of the second battery cell can be applied to predict the open-circuit voltage value of the first battery cell.

[0081] The first and second battery cells may not possess the same characteristics. For example, the first and second battery cells may be produced in different batches, or the types of the first and second battery cells may be different, such as the first battery cell being a pouch cell and the second battery cell being a laminated cell. Alternatively, the constituent materials of the first and second battery cells may be different. When the first and second battery cells have different characteristics, the embodiments of this application can support adjustments or fine-tuning of the aforementioned model (which can be adjusted arbitrarily) so that the aforementioned model can be applied to predict the open-circuit voltage value of the first battery cell.

[0082] One possible implementation is that the lower limit and upper limit of the time range corresponding to the multiple resting times of the second battery cell are 10 days and 90 days, respectively.

[0083] By selecting the aforementioned time range, the reliability of the open-circuit voltage values ​​of individual battery cells can be ensured, while the testing cycle can be reduced, thereby lowering costs. Specifically, since the reliability of the open-circuit voltage values ​​of the second battery cell before 10 days of rest is lower due to the influence of battery polarization, excluding the open-circuit voltage values ​​of the second battery cell before 10 days of rest ensures the reliability of the training data, thereby improving the accuracy of the aforementioned model.

[0084] When the time range corresponding to the multiple resting times of the second battery cell is from 10 days to 90 days, the multiple open-circuit voltage values ​​of the second battery cell can include the open-circuit voltage values ​​corresponding to some resting times within this time range. For example, the multiple open-circuit voltage values ​​of the second battery cell can include the open-circuit voltage values ​​corresponding to the time range of 20 days to 60 days of resting.

[0085] As an example, this application embodiment supports testing the open-circuit voltage of the second battery cell once a day, which can obtain the open-circuit voltage values ​​of 90 second battery cells. The multiple open-circuit voltage values ​​of the second battery cells can include some or all of the open-circuit voltage values ​​of the 90 open-circuit voltage values, excluding the open-circuit voltage values ​​of the second battery cells before they were placed 10 days ago.

[0086] As an example, this application embodiment supports testing the open-circuit voltage of the second battery cell every 5 days, so the open-circuit voltage values ​​of 32 second battery cells can be obtained. The multiple open-circuit voltage values ​​of the second battery cells can include some or all of the open-circuit voltage values ​​of the 32 open-circuit voltage values, excluding the open-circuit voltage values ​​of the second battery cells before they were placed 10 days ago.

[0087] As an example, this application embodiment supports testing the open-circuit voltage of the second battery cell every 7 days, so the open-circuit voltage values ​​of 15 second battery cells can be obtained. The multiple open-circuit voltage values ​​of the second battery cells can include some or all of the open-circuit voltage values ​​of the 15 open-circuit voltage values, excluding the open-circuit voltage values ​​of the second battery cells before they were placed 10 days ago.

[0088] As an example, this application embodiment supports testing the open-circuit voltage of the second battery cell every 10 days, so the open-circuit voltage values ​​of 10 second battery cells can be obtained. The multiple open-circuit voltage values ​​of the second battery cells can include part or all of the open-circuit voltage values ​​of the 10 open-circuit voltage values, excluding the open-circuit voltage values ​​of the second battery cells before they were placed 10 days ago.

[0089] One possible implementation is that the model parameters of the first model include a first coefficient, a second coefficient, and a third coefficient, the values ​​of which are all related to the self-discharge effect of the battery cell based on chemical reaction.

[0090] The above model enables the prediction of the open-circuit voltage of a battery cell that experiences self-discharge due to chemical reactions.

[0091] One possible implementation, the first model satisfies: V is the open-circuit voltage value, a1 is the first coefficient, b1 is the second coefficient, c1 is the third coefficient, t represents the settling time, and e represents the natural constant (its value is approximately 2.71828).

[0092] The above model supports the prediction of open-circuit voltage output by the first model to be relatively close to the actual open-circuit voltage value of the first battery cell, that is, the reliability of the prediction of open-circuit voltage output by the first model is high.

[0093] The above model is for illustrative purposes only. Embodiments of this application can support the generation of new models based on the above model, for example, ,or, .

[0094] One possible implementation is that b1 is related to one or more of the following: the amount of charge transfer, the Faraday constant, the gas constant, and the initial open-circuit voltage of the battery cell; and c1 is related to the amount of charge transfer z, the Faraday constant R, the gas constant F1, and the exchange current density I. 01 It is related to one or more of the self-discharge equivalent capacitance C and the resting time of the battery cell, and a1 is related to the discharge cutoff voltage of the battery cell.

[0095] The above model can make the open-circuit voltage prediction value output by the first model more reliable.

[0096] When a1 is related to the discharge cutoff voltage of a single battery cell, the value of a can be equal to the discharge cutoff voltage of the single battery cell, or the value of a1 can be equal to the difference between the discharge cutoff voltage of the single battery cell and a fixed value. The value of a1 can also be obtained based on the open-circuit voltage of the second battery cell after a long period of rest. For example, if the resting time of the second battery cell is 90 days, the value of a1 can be determined based on the open-circuit voltage of the second battery cell after 90 days of rest. Here, the aforementioned open-circuit voltage after a long period of rest can be understood as the open-circuit voltage of the second battery cell after infinite rest. Furthermore, the discharge cutoff voltage can also be replaced by a known lower voltage limit, etc.

[0097] When b1 is related to one or more of z, F, R and the initial open-circuit voltage of the battery cell, and c1 is related to z, F, R, I 01 When the parameters related to b1 and c1 are related to one or more of the self-discharge equivalent capacitance and the resting time of the battery cell, there are many ways to combine the parameters related to b1 and c1. The embodiments of this application do not limit the specific combination of the parameters related to b1 and c1.

[0098] For example, b1 is related to z, and c1 is related to F, such as b1 being z or b1 being a constant determined based on z, and c1 being F or c1 being a constant determined based on F. As another example, b1 is related to both z and F, and c1 is related to R and z, such as b1 being a combination of z and F or b1 being a constant determined based on z and F, and c1 being a combination of R and z or c1 being a constant determined based on R and z.

[0099] One possible implementation is that the model parameters of the second model include the fourth, fifth, sixth, seventh, and eighth coefficients. The fourth, fifth, and sixth coefficients are all related to the self-discharge effect of the battery cell based on chemical reactions, while the seventh and eighth coefficients are both related to the self-discharge effect of the battery cell based on physical factors.

[0100] The above model enables the prediction of the open-circuit voltage of a battery cell that experiences self-discharge due to chemical reactions and physical factors.

[0101] One possible implementation, the second model satisfies: V is the open-circuit voltage value, a2 represents the fourth coefficient, b2 represents the fifth coefficient, c2 represents the sixth coefficient, d represents the seventh coefficient, f represents the eighth coefficient, t represents the settling time, and e represents the natural constant.

[0102] Based on the above model, since both the seventh and eighth coefficients are related to the self-discharge effect of the first battery cell based on physical factors, this can support the application of the second model to predict the open-circuit voltage of the first battery cell with a physical internal short circuit.

[0103] The above model is for illustrative purposes only. Embodiments of this application can support the generation of new models based on the above model, for example, ,or, + .

[0104] One possible implementation is that b2 is related to one or more of the following: the amount of charge transferred, the Faraday constant, the gas constant, and the initial open-circuit voltage of the battery cell; and c2 is related to the amount of charge transferred z, the Faraday constant R, the gas constant F2, and the exchange current density I. 02 a2 is related to one or more of the self-discharge equivalent capacitance C and the resting time of the battery cell, and is related to the discharge cutoff voltage of the battery cell.

[0105] The above model can make the open-circuit voltage prediction value output by the second model more reliable.

[0106] When a2 is related to the discharge cutoff voltage of a single battery cell, the value of a2 can be equal to the discharge cutoff voltage of the single battery cell, or the value of a2 can be equal to the difference between the discharge cutoff voltage of the single battery cell and a fixed value. The value of a2 can also be obtained based on the open-circuit voltage of the second battery cell after a long period of rest. For example, if the resting time of the second battery cell is 90 days, the value of a2 can be determined based on the open-circuit voltage of the second battery cell after 90 days of rest. Here, the aforementioned open-circuit voltage after a long period of rest can be understood as the open-circuit voltage of the second battery cell after infinite rest. Furthermore, the discharge cutoff voltage can also be replaced by a known lower voltage limit, etc.

[0107] When b2 is related to one or more of z, F, R and the initial open-circuit voltage of the battery cell, and c2 is related to z, F, R, I 02 When the parameters related to b2 and c2 are related to one or more of the self-discharge equivalent capacitance and the resting time of the battery cell, there are many ways to combine the parameters related to b2 and c2. The embodiments of this application do not limit the specific combination of the parameters related to b2 and c2.

[0108] For example, b2 is related to z, and c2 is related to F, such as b2 being z or b2 being a constant determined based on z, and c2 being F or c2 being a constant determined based on F. As another example, b2 is related to both z and F, and c2 is related to R and z, such as b2 being a combination of z and F or b2 being a constant determined based on z and F, and c2 being a combination of R and z or c2 being a constant determined based on R and z.

[0109] The above model will be described below with specific examples.

[0110] One possible implementation, the first model satisfies:

[0111]

[0112] The above model is based on the self-discharge effect of the battery cell based on chemical reactions. Specifically, the above formula can characterize the leakage current model of the battery cell based on the side reactions on the positive and negative electrodes.

[0113] Where, a1= b1= c1= .

[0114] One possible implementation, the second model satisfies:

[0115] +

[0116] The above model is determined based on the self-discharge effect of individual battery cells based on chemical reactions and the self-discharge effect based on physical factors.

[0117] Among them, V t V0 is the open-circuit voltage of a single battery cell after it has been left to rest for time t, and V0 is the initial open-circuit voltage of the single battery cell. ∞ It is the open-circuit voltage value of a single battery cell after it has been left to stand for an infinitely long time, V. ∞ It can also be understood as the discharge cutoff voltage or equilibrium potential of a single battery cell, z is the amount of charge transferred, F is the Faraday constant, R is the gas constant, I0 is the exchange current density, t is the resting time of the single battery cell, and T represents the temperature of the environment in which the single battery cell is located.

[0118] Where, a2= b2= c2= d= f= During model training, The value can be determined based on multiple open-circuit voltage values ​​of the first battery cell. For example, when the last three resting times of the first battery cell are 25 days, 27 days, and 30 days, this embodiment can support averaging the sum of the open-circuit voltage values ​​corresponding to a resting time of 25 days, a resting time of 27 days, and a resting time of 30 days for the first battery cell. This average value is... The value of can be determined, or, during model iteration, based on the aforementioned average value. The final value of .

[0119] During model training, The value of is related to the ambient temperature and SOC of the first battery cell, therefore it can be constructed The initial value, for example, The initial value is 0.001, and it can be updated during subsequent model training. The initial value.

[0120] During model training, The value of is related to the electrochemical parameters of the constituent materials of the first battery cell, therefore, it is possible to construct... The initial value, for example, The initial value is 0.001, and it can be updated during subsequent model training. The initial value.

[0121] During model training, the embodiments of this application can support the following: , as well as Each setting its own corresponding value range, for example, The value range is 2.0 to 4.3. The value range is -1 to 1. The value range is -2 to 2.

[0122] During model training, this application embodiment can support setting corresponding value ranges for d and f respectively. For example, the value range of d is -1 to 0, and the value range of f is 0 to 1.

[0123] Once the above parameters are determined, embodiments of this application can support model training using multiple resting times of the first battery cell and multiple open-circuit voltage values ​​corresponding one-to-one with the multiple resting times of the first battery cell, so as to obtain the aforementioned model.

[0124] The above model is only an example. Embodiments of this application can support the determination of new models based on the aforementioned models, for example, For example, wait.

[0125] For ease of description, the following description will take the example of model training based on multiple resting times and multiple open-circuit voltage values ​​of the second battery cell.

[0126] To further improve the reliability of the open-circuit voltage values ​​output by the aforementioned model, embodiments of this application can support adjusting the initial charge of the second battery cell according to actual shipping requirements, and determining the open-circuit voltage value of the second battery cell after long-term resting based on the initial charge of the second battery cell. That is, multiple resting times of the second battery cell and multiple open-circuit voltage values ​​corresponding to the multiple resting times are determined based on the initial charge of the second battery cell.

[0127] For example, if a customer requires the initial charge level of a single battery cell to be 40% SOC, this embodiment of the application can support adjusting the initial charge level of the second battery cell to 40% SOC. Specifically, this embodiment of the application can support adjusting the initial charge level of the second battery cell to the customer's required charge level through either of the following two methods.

[0128] Method 1: Discharge first, then charge.

[0129] Method 1 includes the following steps:

[0130] Step 1: Let it stand for 10 minutes to allow polarization to dissipate;

[0131] Step 2: The second battery cell discharges at a constant DC current of 0.05 times until the voltage of the second battery cell drops to the preset minimum cutoff voltage and the discharge stops, that is, the second battery cell is fully discharged.

[0132] Step 3: Let it stand for 10 minutes to allow polarization to dissipate;

[0133] Step 4: The second battery cell is charged with a constant current of 0.05 times until the charge in the second battery cell reaches 40% of the nominal capacity of the second battery cell, at which point charging stops.

[0134] Step 5: Let it stand for 10 minutes to allow polarization to dissipate.

[0135] The parameters mentioned in the above steps are for illustrative purposes only and are not final constraints.

[0136] By using steps 1 to 5 in Method 1, the initial charge of the second battery cell can meet the customer's needs.

[0137] Method 2: Charge first, then discharge.

[0138] Method 2 includes the following steps:

[0139] Step 1: Let it stand for 10 minutes to allow polarization to dissipate;

[0140] Step 2: The second battery cell is charged with a constant current of 0.05 times the rated current until the charge in the second battery cell reaches the nominal capacity of the second battery cell, at which point charging stops, thus achieving full charge of the second battery cell.

[0141] Step 3: Let it stand for 10 minutes to allow polarization to dissipate;

[0142] Step 4: The second battery cell is discharged at a constant DC current of 0.05 times until the SOC of the second battery cell is 40% of the nominal capacity of the second battery cell and then the discharge stops.

[0143] Step 5: Let it stand for 10 minutes to allow polarization to dissipate.

[0144] The parameters mentioned in the above steps are for illustrative purposes only and are not final constraints.

[0145] By using steps 1 to 5 in Method 2, the initial charge of the second battery cell can meet the customer's needs.

[0146] When the initial charge of the second battery cell meets the customer's requirements, this application embodiment can support self-discharge testing of the second battery cell. That is, the second battery cell is stored in a preset environment, such as a normal temperature environment or a high temperature environment, and the open circuit voltage value of the second battery cell is measured at regular intervals using a voltmeter or other equipment (such as an impedance meter). For example, the open circuit voltage value of the second battery cell is measured every 5 or 10 days, and the test time and the corresponding open circuit voltage value of the second battery cell are recorded.

[0147] The following describes the process of training a model using multiple resting times of the second battery cell and the corresponding open-circuit voltage values ​​for each resting time. The following description uses the training of the first model as an example, but the content also applies to the training of the second model. It should be noted that in the accompanying figures, the horizontal axis represents the resting time of the battery cell in days, and the vertical axis represents the open-circuit voltage value of the battery cell in volts (V), which will not be elaborated further.

[0148] Figure 3 This illustrates a schematic diagram of the training of the first model. (For example...) Figure 3As shown, the dots represent the actual open-circuit voltage values ​​of the second battery cell. The resting time of the second battery cell corresponding to the actual open-circuit voltage values ​​falls within this time range: a resting time of 0 days and a resting time of 90 days. The fitted curve represents the trend of the predicted open-circuit voltage values ​​output by the first model based on 10 open-circuit voltage values ​​out of the 20 open-circuit voltage values ​​and the corresponding 10 resting times. That is, the open-circuit voltage values ​​of the second battery cell before 10 days of resting are excluded, and the open-circuit voltage values ​​of the second battery cell after 10 days of resting are selected.

[0149] Figure 3 In the equation, a = 3.57642, b = 0.056277, and c = -0.001375. The first model is: V = 3.57642 + 0.056277 .

[0150] Figure 4 This diagram illustrates the relationship between the predicted open-circuit voltage output from the first model and the actual open-circuit voltage of the second battery cell. Figure 4 There is no physical internal short circuit within the battery cell corresponding to the content described. For example... Figure 4 As shown, the first model is: V = 3.57642 + 0.056277 The dots represent the open-circuit voltage of the second battery cell before it has been rested for 90 days, the triangles represent the open-circuit voltage of the second battery cell after it has been rested for 90 days, and the fitted curve represents the trend of the predicted open-circuit voltage output by the first model. When the resting time of the second battery cell is less than 175 days, the actual open-circuit voltage of the second battery cell is basically consistent with the predicted open-circuit voltage output by the first model. When the resting time of the second battery cell is greater than 175 days but less than 360 days, there is an error between the actual open-circuit voltage of the second battery cell and the predicted open-circuit voltage output by the first model. The maximum error between the actual open-circuit voltage of the second battery cell and the predicted open-circuit voltage output by the first model is less than 0.001V. Figure 4 It can be seen that the first model has a high accuracy in predicting the open-circuit voltage of a single battery cell after a long period of rest.

[0151] The following text combines Figure 5 The relationship between the predicted open-circuit voltage output by the second model and the actual open-circuit voltage of a battery cell with a physical internal short circuit is described.

[0152] Figure 5 This diagram illustrates a relationship between the predicted open-circuit voltage output from the second model and the actual open-circuit voltage of a battery cell with a physical internal short circuit. Figure 5As shown, the second model is: V = 3.904996 + 0.002214 -0.000021 The dots represent the actual open-circuit voltage values ​​of the second battery cell. The fitted curve shows the trend of the predicted open-circuit voltage value output by the second model. When the resting time of the second battery cell is less than 200 days, the predicted open-circuit voltage value output by the second model is basically consistent with the actual open-circuit voltage value of the second battery cell. When the resting time of the second battery cell is greater than 200 days but less than 360 days, there is a certain error between the predicted open-circuit voltage value output by the second model and the actual open-circuit voltage value of the second battery cell. The maximum error between the predicted open-circuit voltage value output by the second model and the actual open-circuit voltage value of the second battery cell is less than 0.00005.

[0153] The following text combines Figure 6 The relationship between the predicted open-circuit voltage values ​​output by different models and the actual open-circuit voltage values ​​of battery cells with physical internal short circuits is described.

[0154] Figure 6 This diagram illustrates the relationship between the predicted open-circuit voltage values ​​from different models and the actual open-circuit voltage values ​​of battery cells with physical internal short circuits. The dots represent the actual open-circuit voltage values ​​of the second battery cell, and the fitted curves represent the changing trends of the predicted open-circuit voltage values ​​output by the open-circuit voltage models. Figure 6 The model shown was obtained by training the model based on the open-circuit voltage values ​​of the second battery cell during the resting period of 10 to 90 days.

[0155] like Figure 6 As shown in (a), the first model is: V = 3.902480 + 0.004228 When the resting time of the second battery cell is less than 100 days, the actual open-circuit voltage value of the second battery cell is basically consistent with the predicted open-circuit voltage value output by the first model. When the resting time of the second battery cell is greater than 100 days but less than 360 days, there is an error between the actual open-circuit voltage value of the second battery cell and the predicted open-circuit voltage value output by the first model, and this error increases with the increase of the resting time of the second battery cell.

[0156] like Figure 6 As shown in (b), the second model is: V = 3.904996 + 0.002214 -0.000021 When the resting time of the second battery cell is less than 250 days, the actual open-circuit voltage value of the second battery cell is basically consistent with the predicted open-circuit voltage value output by the second model. When the resting time of the second battery cell is greater than 250 days but less than 360 days, there is a small error between the actual open-circuit voltage value of the second battery cell and the predicted open-circuit voltage value output by the second model.

[0157] contrast Figure 6 As shown in (a) and (b), the second model can predict the self-discharge degradation of individual battery cells after a long period of rest with relatively high accuracy. In addition, the second model can also accurately capture the degradation sources of interfacial chemical reactions and physical internal short circuits in the training data, thus enabling it to output a more accurate predicted value of open-circuit voltage.

[0158] Figure 6 The description is based on the example of using the open-circuit voltage values ​​corresponding to the resting time of the second battery cell in the range of 10 to 90 days for model training. Since the model training effect of the open-circuit voltage values ​​corresponding to the resting time of the second battery cell in the range of 20 to 60 days is basically the same as that of the open-circuit voltage values ​​corresponding to the resting time of the second battery cell in the range of 10 to 90 days, it will not be elaborated further.

[0159] The following text combines Figures 7 to 12 The relationship between the first model and the second model is further described. Specifically, Figure 7 The content described refers to battery cell 1. Figure 8 The content shown refers to battery cell 2. Figure 9 The content shown refers to battery cell 3. Figure 10 The content shown refers to battery cell 4. Figure 11 The content shown refers to battery cell 5. Figure 12 The content shown refers to battery cell 1, battery cell 2, battery cell 3, battery cell 4, and battery cell 5.

[0160] Figure 7 A schematic diagram illustrating a relationship between the first model and the second model is shown. Figure 7 In the first model, V = 3.538994 + 0.04373 × The second model is V = 3.536491 + 0.046224 × -0.000009×t 1.00001 For example:

[0161] like Figure 7As shown in (a), curve 1 represents the trend of the predicted open-circuit voltage output by the first model, and curve 2 represents the trend of the predicted open-circuit voltage output by the second model. When the resting time of battery cell 1 is less than or equal to 150 days, the predicted open-circuit voltage of battery cell 1 output by the first model is the same as that output by the second model. When the resting time of battery cell 1 is greater than 150 days, the predicted open-circuit voltage of battery cell 1 output by the first model is different from that output by the second model. The description of the difference between the predicted open-circuit voltage of battery cell 1 output by the first model and the predicted open-circuit voltage of battery cell 1 output by the second model can be found in [reference needed]. Figure 7 (b)

[0162] like Figure 7 As shown in (b), the curve represents the trend of the difference between the predicted open-circuit voltage of battery cell 1 output by the first model and the predicted open-circuit voltage of battery cell 1 output by the second model. When the resting time of battery cell 1 is less than or equal to 150 days, the difference between the predicted open-circuit voltage of battery cell 1 output by the first model and the predicted open-circuit voltage of battery cell 1 output by the second model is basically 0. When the resting time of battery cell 1 is greater than 150 days, the difference between the predicted open-circuit voltage of battery cell 1 output by the first model and the predicted open-circuit voltage of battery cell 1 output by the second model increases with the increase of resting time, but the overall trend of change is relatively slow, that is, the slope of the curve is small.

[0163] Figure 8 A schematic diagram illustrating yet another relationship between the first and second models is shown. Figure 8 In the first model, V = 3.90248 + 0.004228 × The second model is: V = 3.904996 + 0.002214 × -0.000021×t 0.999724 For example:

[0164] like Figure 8As shown in (a), curve 1 represents the trend of the predicted open-circuit voltage output by the first model, and curve 2 represents the trend of the predicted open-circuit voltage output by the second model. When the resting time of battery cell 1 is less than or equal to 100 days, the predicted open-circuit voltage of battery cell 2 output by the first model is the same as that output by the second model. When the resting time of battery cell 2 is greater than 100 days, the predicted open-circuit voltage of battery cell 2 output by the first model is different from that output by the second model. The description of the difference between the predicted open-circuit voltage of battery cell 2 output by the first model and the predicted open-circuit voltage of battery cell 2 output by the second model can be found in [reference needed]. Figure 8 (b)

[0165] like Figure 8 As shown in (b), the curve represents the trend of the difference between the predicted open-circuit voltage of battery cell 2 output by the first model and the predicted open-circuit voltage of battery cell 2 output by the second model. When the resting time of battery cell 2 is less than or equal to 100 days, the difference between the predicted open-circuit voltage of battery cell 1 output by the first model and the predicted open-circuit voltage of battery cell 2 output by the second model is basically 0. When the resting time of battery cell 2 is greater than 150 days, the difference between the predicted open-circuit voltage of battery cell 2 output by the first model and the predicted open-circuit voltage of battery cell 2 output by the second model increases with the increase of resting time, but the overall trend is relatively slow, that is, the slope of the curve is small. In addition, the physical internal shortness of battery cell 2 is relatively large. Under long-term operating conditions, the voltage decay caused by the physical internal shortness increases linearly.

[0166] Figure 9 A schematic diagram illustrating yet another relationship between the first and second models is shown. Figure 9 In the first model, V = 3.611068 + 0.021902 × The second model is: V = 3.632643 + 0.005593 × -0.000057×t 1.00012 For example:

[0167] like Figure 9As shown in (a), curve 1 represents the trend of the predicted open-circuit voltage output by the first model, and curve 2 represents the trend of the predicted open-circuit voltage output by the second model. When the resting time of battery cell 3 is less than or equal to 100 days, the predicted open-circuit voltage of battery cell 3 output by the first model is the same as that output by the second model. When the resting time of battery cell 3 is greater than 100 days, the predicted open-circuit voltage of battery cell 3 output by the first model is different from that output by the second model. The description of the difference between the predicted open-circuit voltage of battery cell 3 output by the first model and the predicted open-circuit voltage of battery cell 3 output by the second model can be found in [reference needed]. Figure 9 (b)

[0168] like Figure 9 As shown in (b), the curve represents the trend of the difference between the predicted open-circuit voltage of battery cell 3 output by the first model and the predicted open-circuit voltage of battery cell 3 output by the second model. When the resting time of battery cell 3 is less than or equal to 100 days, the difference between the predicted open-circuit voltage of battery cell 3 output by the first model and the predicted open-circuit voltage of battery cell 3 output by the second model is basically 0. When the resting time of battery cell 3 is greater than 100 days, the difference between the predicted open-circuit voltage of battery cell 3 output by the first model and the predicted open-circuit voltage of battery cell 3 output by the second model increases with the increase of resting time, but the overall trend is relatively slow, that is, the slope of the curve is small.

[0169] Figure 10 A schematic diagram illustrating yet another relationship between the first and second models is shown. Figure 10 In the first model, V = 3.266597 + 0.01641 × The second model is: V = 3.279814 + 0.004069 × -0.00007×t 0.999899 For example:

[0170] like Figure 10As shown in (a), curve 1 represents the trend of the predicted open-circuit voltage output by the first model, and curve 2 represents the trend of the predicted open-circuit voltage output by the second model. When the resting time of battery cell 4 is less than or equal to 100 days, the predicted open-circuit voltage of battery cell 4 output by the first model is the same as that output by the second model. When the resting time of battery cell 4 is greater than 100 days, the predicted open-circuit voltage of battery cell 4 output by the first model is different from that output by the second model. The description of the difference between the predicted open-circuit voltage of battery cell 4 output by the first model and the predicted open-circuit voltage of battery cell 4 output by the second model can be found in [reference needed]. Figure 10 (b)

[0171] like Figure 10 As shown in (b), the curve represents the trend of the difference between the predicted open-circuit voltage of battery cell 4 output by the first model and the predicted open-circuit voltage of battery cell 4 output by the second model. When the resting time of battery cell 4 is less than or equal to 100 days, the difference between the predicted open-circuit voltage of battery cell 4 output by the first model and the predicted open-circuit voltage of battery cell 4 output by the second model is basically 0. When the resting time of battery cell 4 is greater than 100 days, the difference between the predicted open-circuit voltage of battery cell 4 output by the first model and the predicted open-circuit voltage of battery cell 4 output by the second model increases with the increase of the resting time, but the overall trend is relatively rapid, that is, the slope of the curve is large.

[0172] Figure 11 A schematic diagram illustrating yet another relationship between the first and second models is shown. Figure 11 In the first model, V = 4.12817 + 0.046733 × The second model is V = 4.128959 + 0.045972 × -0.000005×t 1.000009 For example:

[0173] like Figure 11 As shown in (a), since the changing trends of the open-circuit voltage prediction values ​​output by the first model and the second model are basically the same, the curves in the figure can simultaneously represent the changing trends of both the open-circuit voltage prediction values ​​output by the first and second models. As can be seen from the figure, the open-circuit voltage prediction values ​​of battery cell 5 output by the first model and the second model are basically the same. The description of the difference between the open-circuit voltage prediction values ​​of battery cell 5 output by the first model and the second model can be found in [reference needed]. Figure 11 (b)

[0174] like Figure 11 As shown in (b), the curve represents the trend of the difference between the predicted open-circuit voltage of battery cell 5 output by the first model and the predicted open-circuit voltage of battery cell 5 output by the second model. When the resting time of battery cell 5 is less than or equal to 100 days, the difference between the predicted open-circuit voltage of battery cell 5 output by the first model and the predicted open-circuit voltage of battery cell 5 output by the second model is basically 0. When the resting time of battery cell 5 is greater than 100 days, the difference between the predicted open-circuit voltage of battery cell 5 output by the first model and the predicted open-circuit voltage of battery cell 5 output by the second model increases with the increase of resting time, but the overall trend is relatively slow, that is, the slope of the curve is small.

[0175] Figure 12 This diagram illustrates another relationship between the first and second models. Curve 1 represents the trend of the difference between the predicted open-circuit voltage values ​​of battery cell 1 output by different models; Curve 2 represents the trend of the difference between the predicted open-circuit voltage values ​​of battery cell 2 output by different models; Curve 3 represents the trend of the difference between the predicted open-circuit voltage values ​​of battery cell 3 output by different models; Curve 4 represents the trend of the difference between the predicted open-circuit voltage values ​​of battery cell 4 output by different models; and Curve 5 represents the trend of the difference between the predicted open-circuit voltage values ​​of battery cell 5 output by different models. Comparing curves 1 to 5, it can be seen that the physical internal shortness of battery cell 1 and battery cell 5 is relatively low, indicating that the safety levels of battery cell 1 and battery cell 5 are relatively high. Although the physical internal shortness of battery cell 2 and battery cell 3 is relatively large, it is still within an acceptable range. Therefore, the safety levels of battery cell 2 and battery cell 3 can be further assessed. The physical internal shortness of battery cell 4 is greater than that of the other battery cells, indicating that the safety level of battery cell 4 is relatively low.

[0176] The detection method 200 has been described above. The detection apparatus according to an embodiment of this application will now be described. The detection apparatus can execute the detection method 200. The detection apparatus can be a battery management system (BMS), or other types of devices; there is no limitation on this.

[0177] Figure 13 A schematic block diagram of a detection device 1300 according to an embodiment of this application is shown. Figure 13As shown, the detection device 1300 may include: a processing unit 1320, configured to: input a first resting time of the first battery cell into a first model, obtain and output a first open-circuit voltage value corresponding to the first resting time, wherein the first model is determined based on the self-discharge effect of the first battery cell based on chemical reaction; input the first resting time into a second model, obtain and output a second open-circuit voltage value corresponding to the first resting time, wherein the second model is determined based on the self-discharge effect of the first battery cell based on chemical reaction and the self-discharge effect based on physical factors; and determine the safety level of the first battery cell based on the absolute value of the difference between the first open-circuit voltage value and the second open-circuit voltage value.

[0178] Optionally, the detection device 1300 may further include a communication unit 1310, which is used to acquire the first resting time of the first battery cell.

[0179] The detection device 1300 can perform the corresponding operations in the detection method 200, which will not be described in detail here for the sake of brevity.

[0180] Figure 14 A schematic diagram of the hardware structure of the detection device 1400 according to an embodiment of this application is shown. The detection device 1400 includes a memory 1401, a processor 1402, a communication interface 1403, and a bus 1404. The memory 1401, the processor 1402, and the communication interface 1403 are interconnected via the bus 1404.

[0181] The memory 1401 can be a read-only memory (ROM), a static storage device, or a random access memory (RAM). The memory 1401 can store programs, and when the program stored in the memory 1401 is executed by the processor 1402, the processor 1402 and the communication interface 1403 are used to execute the various steps of the detection method 200.

[0182] The processor 1402 may be a general-purpose central processing unit (CPU), microprocessor, application-specific integrated circuit (ASIC), graphics processing unit (GPU), or one or more integrated circuits, for executing related programs to achieve the functions required by the units in the apparatus of this application embodiment, or to execute the detection method 200.

[0183] The processor 1402 can also be an integrated circuit chip with signal processing capabilities. During implementation, each step of the detection method 200 can be completed through integrated logic circuits in the processor 1402 or through software instructions.

[0184] Processor 1402 can also be a general-purpose processor, digital signal processor (DSP), ASIC, field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly implemented by the hardware processor, or implemented by a combination of hardware and software modules in the processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory 1401. Processor 1402 reads information from memory 1401 and, in conjunction with its hardware, completes the functions required by the units included in the detection device 1400, or executes detection method 200.

[0185] The communication interface 1403 uses a transceiver device, such as, but not limited to, a transceiver, to enable communication between the detection device 1400 and other devices or communication networks.

[0186] Bus 1404 may include a pathway for transmitting information between various components of the detection device 1400 (e.g., memory 1401, processor 1402, communication interface 1403).

[0187] The detection device 1400 only shows the memory, processor, and communication interface. In specific implementations, the detection device 1400 may also include other devices necessary for normal operation. Furthermore, depending on specific needs, the detection device 1400 may also include hardware devices to implement other additional functions. Moreover, those skilled in the art should understand that the detection device 1400 may also include only the devices necessary for implementing this application, and may not necessarily include... Figure 14 All the devices shown.

[0188] This application also provides a computer-readable storage medium for storing a computer program that performs the methods described in the various embodiments of this application. The computer-readable storage medium can be a transient computer-readable storage medium or a non-transitory computer-readable storage medium.

[0189] This application also provides a computer program product, which includes a computer program stored on a computer-readable storage medium. The computer program includes program instructions that, when executed by a computer, cause the computer to perform the above-described battery detection method.

[0190] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method of detection, characterized in that, The method comprises the following steps: inputting a first standing time of a first battery cell into a first model to obtain and output a first open circuit voltage value corresponding to the first standing time, wherein the first model is obtained by model training according to a plurality of standing times of the first battery cell, a plurality of open circuit voltage values of the first battery cell, and a self-discharge effect of the first battery cell based on a chemical reaction; inputting the first standing time into a second model to obtain and output a second open circuit voltage value corresponding to the first standing time, wherein the second model is obtained by model training according to a plurality of standing times of the first battery cell, a plurality of open circuit voltage values of the first battery cell, and a self-discharge effect of the first battery cell based on a chemical reaction and a self-discharge effect based on a physical factor, wherein the plurality of open circuit voltage values of the first battery cell and the plurality of standing times of the first battery cell correspond to each other in a one-to-one manner; determining a safety degree of the first battery cell according to an absolute value of a difference between the first open circuit voltage value and the second open circuit voltage value.

2. The method of claim 1, wherein, The method for determining the safety degree of the first battery cell according to the absolute value of the difference between the first open circuit voltage value and the second open circuit voltage value comprises: determining the safety degree of the first battery cell according to the absolute value of the difference between the first open circuit voltage value and the second open circuit voltage value and a preset threshold value.

3. The method according to claim 1 or 2, characterized in that, The model parameters of the first model comprise a first coefficient, a second coefficient, and a third coefficient, wherein the first coefficient, the second coefficient, and the third coefficient are all related to the self-discharge effect of the first battery cell based on a chemical reaction.

4. The method of claim 3, wherein, The first model satisfies: , V represents an open circuit voltage value, wherein a1 is the first coefficient, b1 is the second coefficient, c1 is the third coefficient, t represents a standing time, and e represents a natural constant.

5. The method according to claim 1 or 2, characterized in that, The model parameters of the second model comprise a fourth coefficient, a fifth coefficient, a sixth coefficient, a seventh coefficient, and an eighth coefficient, wherein the fourth coefficient, the fifth coefficient, and the sixth coefficient are all related to the self-discharge effect of the first battery cell based on a chemical reaction, and the seventh coefficient and the eighth coefficient are all related to the self-discharge effect of the first battery cell based on a physical factor.

6. The method of claim 5, wherein, The second model satisfies: wherein V represents an open circuit voltage value, a2 represents the fourth coefficient, b2 represents the fifth coefficient, c2 represents the sixth coefficient, d represents the seventh coefficient, f represents the eighth coefficient, t represents a standing time, and e represents a natural constant.

7. A detection device, characterized in that The method comprises the following steps: a processing unit is configured to: input a first standing time of a first battery cell into a first model to obtain and output a first open circuit voltage value corresponding to the first standing time, wherein the first model is obtained by model training according to a plurality of standing times of the first battery cell, a plurality of open circuit voltage values of the first battery cell, and a self-discharge effect of the first battery cell based on a chemical reaction; input the first standing time into a second model to obtain and output a second open circuit voltage value corresponding to the first standing time, wherein the second model is obtained by model training according to a plurality of standing times of the first battery cell, a plurality of open circuit voltage values of the first battery cell, and a self-discharge effect of the first battery cell based on a chemical reaction and a self-discharge effect based on a physical factor, wherein the plurality of open circuit voltage values of the first battery cell and the plurality of standing times of the first battery cell correspond to each other in a one-to-one manner; determine a safety degree of the first battery cell according to an absolute value of a difference between the first open circuit voltage value and the second open circuit voltage value. A safety level of the first battery cell is determined according to an absolute value of a difference between the first open circuit voltage value and the second open circuit voltage value.

8. A detection device, characterized in that Comprising: a memory for storing a program; a processor for executing the program stored in the memory, and when the program stored in the memory is executed, the processor is configured to perform the detection method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, A computer program product for storing a computer program, which causes a computer to execute the detection method according to any one of claims 1 to 6.

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