Lithium deposition detection methods, devices, systems, vehicles, equipment, media and products

Abstract

The embodiment of the present application provides a lithium deposition detection method, device, system, vehicle, equipment, medium and product, the method comprising charging a battery cell at a first charging rate; determining a lithium deposition detection parameter for charging the battery cell at the first charging rate, the lithium deposition detection parameter characterizing the change in thickness of the battery cell with the change in charging capacity; determining a lithium deposition detection parameter for charging the battery cell in a constant pressure state at a second charging rate; determining a lithium deposition threshold value according to the lithium deposition detection parameter for charging the battery cell in a constant pressure state at the second charging rate; wherein the lithium deposition threshold value characterizes the critical value of the change in thickness of the battery cell with the change in charging capacity when lithium deposition occurs; and performing lithium deposition detection on the battery cell according to the lithium deposition detection parameter and the lithium deposition threshold value. In this way, the accuracy of lithium deposition detection can be improved.

Description

Technical Field

[0001] The present application relates to the field of battery detection technology, and in particular to a lithium plating detection method, device, system, vehicle, equipment, medium and product. Background Art

[0002] The lithium deposition problem of lithium batteries is a hot topic in the application and research of lithium batteries during the charging process. After the lithium deposition of the battery, it will pierce the diaphragm, causing the battery to fail. In serious cases, it will also cause greater safety hazards. Therefore, it is very important to detect the lithium deposition of lithium batteries.

[0003] At present, the difference between the expansion force peak values ​​corresponding to the differential capacity peaks between different charging rates is usually used to determine whether the battery cell has lithium deposition. However, the expansion force will be affected by the modulus of the battery cell. During the charging process, the growth law of the expansion force will also change due to the influence of the modulus of the battery cell, resulting in a large error in judging whether the battery cell has lithium deposition based on the difference between the expansion force peak values.

[0004] It can be seen that how to improve the accuracy of lithium plating detection is an urgent problem to be solved. Summary of the invention

[0005] The embodiments of the present application provide a lithium deposition detection method, device, system, vehicle, equipment, medium and product, which can improve the accuracy of lithium deposition detection.

[0006] In a first aspect, an embodiment of the present application provides a lithium deposition detection method, comprising:

[0007] Charging the battery cell using a first charging rate;

[0008] Determine a lithium plating detection parameter when the battery cell is charged at a first charging rate, wherein the lithium plating detection parameter represents a change in thickness of the battery cell as the charging capacity changes;

[0009] The battery cell is tested for lithium deposition according to the lithium deposition test parameters and the lithium deposition threshold value; wherein the lithium deposition threshold value represents the critical value of the thickness change amount of the battery cell as the charging capacity changes when lithium deposition occurs;

[0010] Lithium deposition detection methods also include:

[0011] Determining lithium plating detection parameters for charging the battery cell in a constant pressure state using a second charging rate;

[0012] The lithium deposition threshold is determined according to the lithium deposition detection parameter of charging the battery cell in a constant pressure state using the second charging rate.

[0013] In this embodiment, the lithium deposition detection parameter of the battery cell charged at the first charging rate can be determined, and the lithium deposition detection of the battery cell is performed according to the lithium deposition detection parameter and the lithium deposition threshold, wherein the lithium deposition detection parameter can characterize the change in thickness of the battery cell with the change in charging capacity, that is, the change in thickness of the battery cell with the change in charging capacity can be compared with the lithium deposition threshold reflecting the change critical value, so as to determine whether lithium deposition occurs in the battery cell during the charging process. In this way, since the change in thickness of the battery cell with the change in charging capacity is mainly related to lithium deposition of the battery cell, and is less affected by other external factors, this is used as a basis for judging whether lithium deposition of the battery cell occurs, which can effectively improve the accuracy of lithium deposition detection. In addition, the battery cell can be charged at a second charging rate under a constant pressure state to determine the lithium deposition detection parameter corresponding to the second charging rate, and the lithium deposition detection parameter is less affected by the change in force, so that the accurate lithium deposition threshold can be determined according to the lithium deposition detection parameter, and then the lithium deposition detection can be performed based on the accurate lithium deposition threshold, thereby improving the accuracy of lithium deposition detection.

[0014] In some embodiments, the lithium deposition detection parameter includes a thickness-capacity differential ratio that characterizes the ratio between the differential of the thickness change of the battery cell and the differential of the charging capacity, and determining the lithium deposition detection parameter of the battery cell charged at the first charging rate includes:

[0015] Obtaining a thickness change and a charging capacity of the battery cell when charged at a first charging rate;

[0016] The thickness-capacity differential ratio, which represents the ratio between the differential of the thickness change and the differential of the charging capacity, is used as a lithium plating detection parameter when the battery cell is charged at the first charging rate.

[0017] In this way, the thickness-capacity differential ratio, which is the ratio of the differential of the thickness change to the differential of the charging capacity, can be used as a lithium plating detection parameter for charging the battery cell at the first charging rate. That is, the thickness change under unit charging capacity can be used as a basis for judging whether the battery cell has lithium plating, which further reduces the influence of other external factors on the thickness change of the battery cell, making the judgment result more accurate and further improving the accuracy of lithium plating detection.

[0018] In some embodiments, the lithium deposition detection parameter includes a thickness-to-capacity ratio that characterizes the ratio between the thickness change and the charging capacity of the battery cell, and determining the lithium deposition detection parameter of the battery cell when charged at the first charging rate includes:

[0019] Obtaining a thickness change and a charging capacity of the battery cell when charged at a first charging rate;

[0020] The thickness-to-capacity ratio, which characterizes the ratio between the thickness change and the charging capacity, is used as a lithium plating detection parameter when the battery cell is charged at the first charging rate.

[0021] In this way, the thickness-to-capacity ratio, which is the ratio between the thickness change and the charging capacity, can be used as a lithium plating detection parameter for charging the battery cell at the first charging rate. The thickness-to-capacity ratio is mainly related to the lithium plating of the battery cell and is not affected by the modulus of the battery cell, thereby reducing the error value of the lithium plating detection and improving the accuracy of the lithium plating detection.

[0022] In some embodiments, determining the lithium deposition threshold according to the lithium deposition detection parameter of charging the battery cell in a constant pressure state using the second charging rate includes:

[0023] Determining a thickness capacity change when charging the battery cell at a constant pressure state using a second charging rate;

[0024] The maximum value of the thickness capacity change is determined as the lithium plating threshold.

[0025] In this way, the maximum value of the thickness capacity change can be determined as the lithium deposition threshold, which can reduce the probability of misjudging non-lithium deposition as lithium deposition, and further improve the accuracy of lithium deposition detection.

[0026] In some embodiments, the second charging rate includes a plurality of preset sub-rates, and determining the lithium plating detection parameters for charging the battery cell in a constant pressure state using the second charging rate includes:

[0027] Obtaining the thickness change and charging capacity of the battery cell in a constant pressure state during charging at each preset sub-rate;

[0028] According to the thickness change and the charging capacity, the thickness capacity change corresponding to each preset sub-rate is determined.

[0029] In this way, multiple preset sub-rates can be used for charging, so that the thickness capacity changes corresponding to the multiple preset sub-rates can be obtained. Subsequently, the thickness capacity changes corresponding to the multiple preset sub-rates can be used as the basis for determining the lithium plating threshold, thereby improving the reliability of the lithium plating threshold and further improving the accuracy of lithium plating detection.

[0030] In some embodiments, determining the lithium deposition threshold according to the lithium deposition detection parameter of charging the battery cell in a constant pressure state using the second charging rate includes:

[0031] The maximum value of the thickness capacity change corresponding to each preset sub-rate is determined as a candidate lithium precipitation threshold, and a plurality of candidate lithium precipitation thresholds are obtained;

[0032] The maximum value among multiple candidate lithium precipitation thresholds is determined as the lithium precipitation threshold.

[0033] In this way, the maximum value of the thickness capacity change corresponding to multiple preset sub-rates can be determined as the lithium plating threshold, further reducing the probability of misjudging non-lithium plating as lithium plating, and effectively improving the accuracy of lithium plating detection.

[0034] In some embodiments, the difference between the first sub-ratio and the second sub-ratio is greater than or equal to a preset difference threshold, wherein the first sub-ratio and the second sub-ratio are any two sub-ratios among a plurality of preset sub-ratios.

[0035] In this way, the difference between any two sub-rates is large, which can more comprehensively reflect the thickness capacity changes corresponding to different sub-rates, further improve the reliability of the lithium plating threshold, and effectively improve the accuracy of lithium plating detection.

[0036] In some embodiments, the first charging rate is greater than the second charging rate, and the second charging rate is a charging rate at which lithium plating does not occur in the battery cell.

[0037] In this way, a more reasonable and accurate lithium deposition threshold value can be determined based on the thickness capacity change of the battery cell when charging the battery cell at the second charging rate at which lithium deposition will not occur, thereby further improving the accuracy of lithium deposition detection.

[0038] In some embodiments, when the battery cell is a soft-pack battery cell or a laminated battery cell, the preload force in the constant pressure state ranges from 30 kg to 100 kg;

[0039] When the battery cell is a hard shell battery cell, the preload force value range in the constant pressure state is greater than or equal to 300 kg.

[0040] In this way, for soft-pack batteries or laminated batteries, the preload force is between 30kg and 100kg, and for hard-shell batteries, the preload force can be greater than 300kg. This can ensure that the thickness change of the battery cell is less affected by the change of force under a constant pressure state, while avoiding the loss of the battery cell due to excessive preload force.

[0041] In some embodiments, performing lithium deposition detection on a battery cell according to a lithium deposition detection parameter and a lithium deposition threshold value includes:

[0042] When the lithium deposition detection parameter is greater than the lithium deposition threshold, it is determined that lithium deposition occurs in the battery cell;

[0043] When the lithium deposition detection parameter is less than or equal to the lithium deposition threshold, it is determined that no lithium deposition occurs in the battery cell.

[0044] In this way, the lithium deposition detection parameters can be compared with the lithium deposition threshold value, and whether lithium deposition occurs in the battery cell can be accurately determined based on the comparison result.

[0045] In some embodiments, after performing lithium deposition detection based on the lithium deposition threshold, the method further includes:

[0046] When it is determined that lithium plating occurs in the battery cell, a target instruction is output, where the target instruction is used to instruct to reduce the first charging rate.

[0047] In this embodiment, when lithium deposition occurs in the battery cell, the first charging rate can be reduced to solve the lithium deposition problem, thereby effectively improving the problem of puncturing the diaphragm due to lithium deposition and causing battery failure.

[0048] In a second aspect, the present application also provides a lithium deposition detection device, including:

[0049] A charging module, used to charge the battery cell using a first charging rate;

[0050] A first determination module is used to determine a lithium deposition detection parameter of a battery cell when charging at a first charging rate, wherein the lithium deposition detection parameter represents a change in thickness of the battery cell as a function of charging capacity;

[0051] A detection module is used to perform lithium deposition detection on the battery cell according to the lithium deposition detection parameters and the lithium deposition threshold; wherein the lithium deposition threshold represents the critical value of the thickness change amount of the battery cell as the charging capacity changes when lithium deposition occurs;

[0052] The lithium deposition detection device also includes:

[0053] A second determination module is used to determine the lithium plating detection parameters for charging the battery cell in a constant pressure state using a second charging rate;

[0054] The third determination module is used to determine the lithium deposition threshold value according to the lithium deposition detection parameter of charging the battery cell in a constant pressure state using the second charging rate.

[0055] In this embodiment, the lithium deposition detection parameter of the battery cell charged at the first charging rate can be determined, and the lithium deposition detection of the battery cell is performed according to the lithium deposition detection parameter and the lithium deposition threshold, wherein the lithium deposition detection parameter can characterize the change in thickness of the battery cell with the change in charging capacity, that is, the change in thickness of the battery cell with the change in charging capacity can be compared with the lithium deposition threshold reflecting the change critical value, so as to determine whether lithium deposition occurs in the battery cell during the charging process. In this way, since the change in thickness of the battery cell with the change in charging capacity is mainly related to lithium deposition of the battery cell, and is less affected by other external factors, this is used as a basis for judging whether lithium deposition of the battery cell occurs, which can effectively improve the accuracy of lithium deposition detection. In addition, the battery cell can be charged at a second charging rate under a constant pressure state to determine the lithium deposition detection parameter corresponding to the second charging rate, and the lithium deposition detection parameter is less affected by the change in force, so that the accurate lithium deposition threshold can be determined according to the lithium deposition detection parameter, and then the lithium deposition detection can be performed based on the accurate lithium deposition threshold, thereby improving the accuracy of lithium deposition detection.

[0056] In some embodiments, the lithium deposition detection parameter includes a thickness-capacity differential ratio that characterizes the ratio between the differential of the thickness change of the battery cell and the differential of the charging capacity. The first determination module is further used to:

[0057] Obtaining a thickness change and a charging capacity of the battery cell when charged at a first charging rate;

[0058] The thickness-capacity differential ratio, which represents the ratio between the differential of the thickness change and the differential of the charging capacity, is used as a lithium plating detection parameter when the battery cell is charged at the first charging rate.

[0059] In this way, the thickness-capacity differential ratio, which is the ratio of the differential of the thickness change to the differential of the charging capacity, can be used as a lithium plating detection parameter for charging the battery cell at the first charging rate. That is, the thickness change under unit charging capacity can be used as a basis for judging whether the battery cell has lithium plating, which further reduces the influence of other external factors on the thickness change of the battery cell, making the judgment result more accurate and further improving the accuracy of lithium plating detection.

[0060] In some embodiments, the lithium plating detection parameter includes a thickness-to-capacity ratio characterizing the ratio between the thickness change and the charging capacity of the battery cell. The first determination module is further configured to:

[0061] Obtaining a thickness change and a charging capacity of the battery cell when charged at a first charging rate;

[0062] The thickness-to-capacity ratio, which characterizes the ratio between the thickness change and the charging capacity, is used as a lithium plating detection parameter when the battery cell is charged at the first charging rate.

[0063] In this way, the thickness-to-capacity ratio, which is the ratio between the thickness change and the charging capacity, can be used as a lithium plating detection parameter for charging the battery cell at the first charging rate. The thickness-to-capacity ratio is mainly related to the lithium plating of the battery cell and is not affected by the modulus of the battery cell, thereby reducing the error value of the lithium plating detection and improving the accuracy of the lithium plating detection.

[0064] In some embodiments, the third determining module is further configured to:

[0065] Determining a thickness capacity change when charging the battery cell at a constant pressure state using a second charging rate;

[0066] The maximum value of the thickness capacity change is determined as the lithium plating threshold.

[0067] In this way, the maximum value of the thickness capacity change can be determined as the lithium deposition threshold, which can reduce the probability of misjudging non-lithium deposition as lithium deposition, and further improve the accuracy of lithium deposition detection.

[0068] In some embodiments, the second charging rate includes a plurality of preset sub-rates, and the second determining module is further configured to:

[0069] Obtaining the thickness change and charging capacity of the battery cell in a constant pressure state during charging at each preset sub-rate;

[0070] According to the thickness change and the charging capacity, the thickness capacity change corresponding to each preset sub-rate is determined.

[0071] In this way, multiple preset sub-rates can be used for charging, so that the thickness capacity changes corresponding to the multiple preset sub-rates can be obtained. Subsequently, the thickness capacity changes corresponding to the multiple preset sub-rates can be used as the basis for determining the lithium plating threshold, thereby improving the reliability of the lithium plating threshold and further improving the accuracy of lithium plating detection.

[0072] In some embodiments, the third determining module is further configured to:

[0073] The maximum value of the thickness capacity change corresponding to each preset sub-rate is determined as a candidate lithium precipitation threshold, and a plurality of candidate lithium precipitation thresholds are obtained;

[0074] The maximum value among multiple candidate lithium precipitation thresholds is determined as the lithium precipitation threshold.

[0075] In this way, the maximum value of the thickness capacity change corresponding to multiple preset sub-rates can be determined as the lithium plating threshold, further reducing the probability of misjudging non-lithium plating as lithium plating, and effectively improving the accuracy of lithium plating detection.

[0076] In some embodiments, the difference between the first sub-ratio and the second sub-ratio is greater than or equal to a preset difference threshold, wherein the first sub-ratio and the second sub-ratio are any two sub-ratios among a plurality of preset sub-ratios.

[0077] In this way, the difference between any two sub-rates is large, which can more comprehensively reflect the thickness capacity changes corresponding to different sub-rates, further improve the reliability of the lithium plating threshold, and effectively improve the accuracy of lithium plating detection.

[0078] In some embodiments, the first charging rate is greater than the second charging rate, and the second charging rate is a charging rate at which lithium plating does not occur in the battery cell.

[0079] In this way, a more reasonable and accurate lithium deposition threshold value can be determined based on the thickness capacity change of the battery cell when charging the battery cell at the second charging rate at which lithium deposition will not occur, thereby further improving the accuracy of lithium deposition detection.

[0080] In some embodiments, when the battery cell is a soft-pack battery cell or a laminated battery cell, the preload force in the constant pressure state ranges from 30 kg to 100 kg;

[0081] When the battery cell is a hard shell battery cell, the preload force value range in the constant pressure state is greater than or equal to 300 kg.

[0082] In this way, for soft-pack batteries or laminated batteries, the preload force is between 30kg and 100kg, and for hard-shell batteries, the preload force can be greater than 300kg. This can ensure that the thickness change of the battery cell is less affected by the change of force under a constant pressure state, while avoiding the loss of the battery cell due to excessive preload force.

[0083] In some embodiments, the detection module is further configured to:

[0084] When the lithium deposition detection parameter is greater than the lithium deposition threshold, it is determined that lithium deposition occurs in the battery cell;

[0085] When the lithium deposition detection parameter is less than or equal to the lithium deposition threshold, it is determined that no lithium deposition occurs in the battery cell.

[0086] In this way, the lithium deposition detection parameters can be compared with the lithium deposition threshold value, and whether lithium deposition occurs in the battery cell can be accurately determined based on the comparison result.

[0087] In some embodiments, the lithium precipitation detection device further comprises:

[0088] The output module is used to output a target instruction when it is determined that lithium plating occurs in the battery cell, and the target instruction is used to instruct to reduce the first charging rate.

[0089] In this embodiment, when lithium deposition occurs in the battery cell, the first charging rate can be reduced to solve the lithium deposition problem, thereby effectively improving the problem of puncturing the diaphragm due to lithium deposition and causing battery failure.

[0090] In a third aspect, an embodiment of the present application provides a battery management system, the system including a lithium plating detection device as in the second aspect.

[0091] In a fourth aspect, an embodiment of the present application provides a vehicle, the vehicle comprising a battery management system as in the third aspect.

[0092] In a fifth aspect, an embodiment of the present application provides an electronic device, comprising: a processor and a memory storing program instructions; when the processor executes the program instructions, the method of the first aspect is implemented.

[0093] In a sixth aspect, an embodiment of the present application provides a machine-readable storage medium having program instructions stored thereon, and the method of the first aspect is implemented when the program instructions are executed by a processor.

[0094] In a seventh aspect, an embodiment of the present application provides a computer program product. When instructions in the computer program product are executed by a processor of an electronic device, the electronic device executes the method of the first aspect.

[0095] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0097] Figure 1 A schematic diagram of a lithium deposition detection method provided in an embodiment of the present application;

[0098] Figure 2 A schematic diagram of the thickness variation with the charging capacity in the lithium deposition detection method provided in an embodiment of the present application;

[0099] Figure 3 A schematic diagram of the thickness capacity differential ratio in the lithium deposition detection method provided in an embodiment of the present application;

[0100] Figure 4 A schematic diagram of a specific scenario embodiment of the lithium deposition detection method provided in an embodiment of the present application;

[0101] Figure 5 A schematic diagram of the structure of a lithium deposition detection device provided in an embodiment of the present application;

[0102] Figure 6 A working principle diagram of a battery management system provided in an embodiment of the present application;

[0103] Figure 7 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application.

[0104] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0105] The following detailed description and drawings of the embodiments of the present application are used to illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0106] In the description of the present application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly vertical, but is within the allowable error range. "Parallel" is not strictly parallel, but is within the allowable error range.

[0107] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0108] The difference between the expansion force peak values ​​corresponding to the differential capacity peaks between different charging rates is usually used to determine whether the battery cell has lithium deposition. That is, the expansion force and capacity of the battery can be detected in real time, and a differential curve of the expansion force and capacity is generated based on the expansion force and capacity of the battery. Based on the differential curve of the expansion force and capacity, it is determined whether the battery has lithium deposition.

[0109] However, the applicant found that it is unreasonable to use the peak difference of the expansion force and capacity differential curve between different charging rates as the lithium deposition threshold, because the expansion force is related to two factors, namely the cell modulus and thickness change. Among them, the cell modulus usually refers to the elastic modulus of the cell, specifically the ratio of the strain to the stress generated by the cell under the action of force, which reflects the ability of the cell to resist deformation when subjected to external force.

[0110] It is understandable that lithium deposition causes the modulus of the battery cell to decrease and the thickness to increase, which reflects an increase or decrease in the expansion force. The expansion force will be affected by the modulus of the battery cell. After lithium deposition in the battery cell, the type of side reaction changes, the growth law of the expansion force also changes, and the peak of the differential curve with the capacity moves. Therefore, the error in determining the threshold value by the peak difference is large, resulting in poor accuracy of subsequent lithium deposition detection.

[0111] Based on this, the embodiments of the present application provide a lithium deposition detection method, device, system, vehicle, equipment, medium and product to solve the above technical problems. The lithium deposition detection method provided by the embodiments of the present application is first introduced below.

[0112] Please refer to Figure 1 , Figure 1 A lithium deposition detection method is provided in an embodiment of the present application. The lithium deposition detection method may include:

[0113] Step 101, charging the battery cell at a first charging rate.

[0114] In step 101, the charging rate is a measure of the speed of battery charging, reflecting the ability of the battery to charge to its rated capacity within a specific time, and is usually represented by the letter C. The calculation formula of the charging rate C can be: charging rate C = charging current (A) / battery rated capacity (Ah).

[0115] The first charging rate may refer to the actual charging rate of the battery cell during the lithium deposition detection process. In order to improve the charging efficiency, the first charging rate may generally be a larger charging rate. When charging at this charging rate, the battery cell may be at risk of lithium deposition. For example, Figure 2 and Figure 3 As shown, the first charging rate may be 3C. The battery cell may be charged at the first charging rate.

[0116] Step 102, determining a lithium deposition detection parameter for charging the battery cell at a first charging rate, wherein the lithium deposition detection parameter represents a change in thickness of the battery cell as the charging capacity changes.

[0117] In step 102, when the battery cell is charged at the first charging rate, the thickness change and charging capacity of the battery cell can be monitored in real time, and the thickness change characterizing the change of the battery cell with the charging capacity is determined as the lithium plating detection parameter of the battery cell charged at the first charging rate.

[0118] Among them, the thickness change can reflect the change in the thickness of the battery cell. For example, when the battery cell is not charged, the thickness of the battery cell is h0. As the charging time goes by, at time t1, the thickness of the battery cell is h1, and at time t2, the thickness of the battery cell is h2. Then the thickness change corresponding to t1 is H=h1-h0, and the thickness change corresponding to t2 is H=h2-h0. The charging capacity can reflect the change in the capacity of the battery cell during the charging process. For example, when the battery cell is not charged, the capacity of the battery cell is q0. As the charging time goes by, at time t1, the capacity of the battery cell is q1, and at time t2, the capacity of the battery cell is q2. Then the charging capacity corresponding to t1 is Q=q1-q0, and the charging capacity corresponding to t2 is Q=q2-q0.

[0119] The lithium deposition detection parameter can characterize the change in thickness of the battery cell with the change in charging capacity. In some examples, the lithium deposition detection parameter can be the thickness-to-capacity ratio H / Q of the ratio between the thickness change of the battery cell and the charging capacity. In other examples, the lithium deposition detection parameter can be the thickness-to-capacity differential ratio dH / dQ of the ratio between the differential of the thickness change of the battery cell and the differential of the charging capacity, that is, in this case, the lithium deposition detection parameter can represent the thickness change corresponding to the unit charging capacity.

[0120] Step 103, performing lithium deposition detection on the battery cell according to the lithium deposition detection parameter and the lithium deposition threshold; wherein the lithium deposition threshold represents the critical value of the thickness change amount of the battery cell as the charging capacity changes when lithium deposition occurs.

[0121] In step 103, the lithium deposition detection parameter can be compared with the lithium deposition threshold, and the lithium deposition detection result can be determined according to the comparison result. The lithium deposition threshold can be a critical value determined based on multiple experiments to characterize the thickness change amount of the battery cell when lithium deposition occurs with the change in charging capacity. It can be understood that if the lithium deposition detection parameter characterizes the thickness-to-capacity ratio of the ratio between the thickness change amount of the battery cell and the charging capacity, the corresponding lithium deposition threshold can be the critical value of the thickness-to-capacity ratio when the battery cell produces lithium deposition. If the lithium deposition detection parameter characterizes the thickness-to-capacity differential ratio of the ratio between the differential of the thickness change amount of the battery cell and the differential of the charging capacity, the corresponding lithium deposition threshold can be the critical value of the thickness-to-capacity differential ratio when the battery cell produces lithium deposition.

[0122] In this embodiment, the lithium deposition detection parameters of the battery cell charged at the first charging rate can be determined, and the battery cell is subjected to lithium deposition detection according to the lithium deposition detection parameters and the lithium deposition threshold, wherein the lithium deposition detection parameters can characterize the change in thickness of the battery cell with the change in charging capacity, that is, the change in thickness of the battery cell with the change in charging capacity can be compared with the lithium deposition threshold reflecting the change critical value, thereby determining whether lithium deposition occurs in the battery cell during the charging process. In this way, since the change in thickness of the battery cell with the change in charging capacity is mainly related to lithium deposition of the battery cell and is less affected by other external factors, this can be used as a basis for determining whether the battery cell has lithium deposition, which can effectively improve the accuracy of lithium deposition detection.

[0123] In some embodiments, the lithium deposition detection parameter includes a thickness-capacity differential ratio that characterizes the ratio between the differential of the thickness change of the battery cell and the differential of the charging capacity, and determining the lithium deposition detection parameter of the battery cell charged at the first charging rate includes:

[0124] Obtaining a thickness change and a charging capacity of the battery cell when charged at a first charging rate;

[0125] The thickness-capacity differential ratio, which represents the ratio between the differential of the thickness change and the differential of the charging capacity, is used as a lithium plating detection parameter when the battery cell is charged at the first charging rate.

[0126] In this embodiment, the thickness change H and the charging capacity Q of the battery cell charged at the first charging rate can be obtained. It can be understood that as the charging time increases, the charging capacity usually increases linearly. However, due to the side reactions inside the battery cell during the charging process, the change in the thickness of the battery cell increases nonlinearly with the increase in charging time. At this time, if a fixed lithium precipitation threshold is used to determine whether lithium precipitation occurs, misjudgment may occur. Based on this, the thickness change of the battery cell under unit charging capacity can be calculated and used as a basis for determining whether lithium precipitation occurs in the battery cell.

[0127] In other words, the thickness-capacity differential ratio dH / dQ, which characterizes the ratio between the differential of the thickness change and the differential of the charging capacity, can be used as a lithium plating detection parameter when the battery cell is charged at the first charging rate, and the thickness-capacity differential ratio dH / dQ can be used to determine whether lithium plating occurs in the battery cell.

[0128] In this way, the thickness-capacity differential ratio, which is the ratio of the differential of the thickness change to the differential of the charging capacity, can be used as a lithium plating detection parameter for charging the battery cell at the first charging rate. That is, the thickness change under unit charging capacity can be used as a basis for judging whether the battery cell has lithium plating, which further reduces the influence of other factors on the thickness change of the battery cell, making the judgment result more accurate and further improving the accuracy of lithium plating detection.

[0129] In some embodiments, the lithium deposition detection parameter includes a thickness-to-capacity ratio that characterizes the ratio between the thickness change and the charging capacity of the battery cell, and determining the lithium deposition detection parameter of the battery cell when charged at the first charging rate includes:

[0130] Obtaining a thickness change and a charging capacity of the battery cell when charged at a first charging rate;

[0131] The thickness-to-capacity ratio, which characterizes the ratio between the thickness change and the charging capacity, is used as a lithium plating detection parameter when the battery cell is charged at the first charging rate.

[0132] In this embodiment, the thickness change H and the charging capacity Q of the battery cell when charged at the first charging rate can be obtained, and the thickness-to-capacity ratio H / Q, which characterizes the ratio between the thickness change and the charging capacity, is directly used as a lithium plating detection parameter when the battery cell is charged at the first charging rate, and the thickness-to-capacity ratio H / Q is used to determine whether lithium plating occurs in the battery cell.

[0133] At this time, in order to ensure the accuracy of lithium deposition detection, the corresponding lithium deposition threshold can be matched according to different charging capacities, and then the thickness capacity ratio H / Q is compared with the matched lithium deposition threshold, and the lithium deposition detection result is obtained according to the comparison result.

[0134] In this way, the thickness-to-capacity ratio, which is the ratio between the thickness change and the charging capacity, can be used as a lithium plating detection parameter for charging the battery cell at the first charging rate. The thickness-to-capacity ratio is mainly related to the lithium plating of the battery cell and is not affected by the modulus of the battery cell, thereby reducing the error value of the lithium plating detection and improving the accuracy of the lithium plating detection.

[0135] In some embodiments, the lithium deposition detection method may further include:

[0136] Determining lithium plating detection parameters for charging the battery cell in a constant pressure state using a second charging rate;

[0137] The lithium deposition threshold is determined according to the lithium deposition detection parameter of charging the battery cell in a constant pressure state using the second charging rate.

[0138] In this embodiment, the battery cell being in a constant pressure state may mean that the spatial pressure of the battery cell does not change during the entire charging process and is maintained within a constant allowable range. It is understandable that during the charging process, the thickness of the battery cell will expand to a certain extent due to the embedding of lithium ions in the interplanar spacing of the graphite lattice. Applying a constant pressure can reduce the expansion of the battery cell to a certain extent, thereby reducing the effect of the change in force on the thickness of the battery cell, resulting in the lithium plating detection parameter being less affected by the change in force.

[0139] When the battery cell is under a constant pressure state, the battery cell can be charged at a second charging rate to obtain the lithium plating detection parameters of the battery cell at this time. The second charging rate can be a charging rate at which the battery cell will not plating lithium during the charging process. For example, the second charging rate can be a small rate less than or equal to 1C. It is understandable that the second charging rate can be a small rate selected based on an empirical value, or it can be a plurality of randomly determined small rates, which is not specifically limited here.

[0140] It is understandable that the lithium plating detection parameter for charging the battery cell in a constant pressure state using the second charging rate can also characterize the change in the thickness change of the battery cell with the change in the charging capacity. And matching the lithium plating detection parameter corresponding to the first charging rate, in some examples, the lithium plating detection parameter may be a thickness-capacity differential ratio that characterizes the ratio between the differential of the thickness change of the battery cell and the differential of the charging capacity. In other examples, the lithium plating detection parameter may be a thickness-capacity ratio that characterizes the ratio between the thickness change of the battery cell and the charging capacity. The method for determining the lithium plating detection parameter is as mentioned above and will not be repeated here.

[0141] The lithium deposition threshold can be determined according to the lithium deposition detection parameters for charging the battery cell in a constant pressure state using a second charging rate. For example, the maximum value of the thickness capacity change represented by the lithium deposition detection parameters can be determined as the lithium deposition threshold K. Alternatively, the sum of the average value of the thickness capacity change represented by the lithium deposition detection parameters and a preset constant term can be determined as the lithium deposition threshold K. Alternatively, the weighted average value of the thickness capacity change represented by the lithium deposition detection parameters can be determined as the lithium deposition threshold K. It can be set specifically according to actual needs and is not specifically limited here. Among them, the thickness capacity change can include a thickness capacity ratio or a thickness capacity differential ratio.

[0142] In this way, the battery cell can be charged at a second charging rate under a constant pressure state to determine the lithium deposition detection parameters corresponding to the second charging rate, and the lithium deposition detection parameters are less affected by the change in force. Therefore, an accurate lithium deposition threshold can be determined based on the lithium deposition detection parameters, and then lithium deposition detection can be performed based on the accurate lithium deposition threshold, thereby improving the accuracy of lithium deposition detection.

[0143] In some embodiments, determining the lithium deposition threshold according to the lithium deposition detection parameter of charging the battery cell in a constant pressure state using the second charging rate includes:

[0144] Determining a thickness capacity change when charging the battery cell at a constant pressure state using a second charging rate;

[0145] The maximum value of the thickness capacity change is determined as the lithium plating threshold.

[0146] In this embodiment, the thickness capacity change of charging the battery cell in a constant pressure state using the second charging rate at which lithium plating does not occur can be determined, wherein the thickness capacity change can be a thickness capacity ratio or a thickness capacity differential ratio.

[0147] It is understandable that during the charging process of the battery cell, the process of lithium ions moving from the positive electrode to the negative electrode is the "embedding" process. At this time, the lithium ions in the positive electrode material are released from the positive electrode material under the action of the electric field, and the released lithium ions then migrate through the electrolyte and are finally embedded in the negative electrode material, specifically, they can be embedded in the interplanar spacing within the graphite lattice.

[0148] Lithium ions are not unlimited when embedded in the negative electrode material. Lithium plating will occur when the load is exceeded. During the lithium plating process, lithium metal is preferentially deposited on the top surface of the negative electrode instead of utilizing the interplanar spacing within the graphite lattice. For the same number of lithium ions, lithium plating will cause a more significant increase in thickness than embedding, so lithium plating causes a much higher thickness change per unit charge than embedding.

[0149] Take the thickness capacity change as the thickness capacity differential ratio as an example. The above-mentioned thickness change of lithium deposition is greater than the thickness change of embedding, which can be described by the differential derivative of the thickness change to the charge capacity, and the expression is as follows:

[0150]

[0151] Wherein, H is the thickness change of the battery cell, and Q is the charging capacity of the battery cell. Based on this, in the embedding process (i.e., the process of charging the battery cell at the second charging rate), the maximum value of the thickness-capacity differential ratio dH / dQ can be selected as the lithium deposition threshold K to identify lithium deposition. In the process of charging the battery cell at the first charging rate, the corresponding lithium deposition detection parameter dH / dQ will remain below the lithium deposition threshold K during the embedding process, but will exceed the lithium deposition threshold K when lithium deposition occurs.

[0152] In this way, the maximum value of the thickness capacity change can be determined as the lithium deposition threshold, which can reduce the probability of misjudging non-lithium deposition as lithium deposition, and further improve the accuracy of lithium deposition detection.

[0153] In some embodiments, the second charging rate includes a plurality of preset sub-rates, and determining the lithium plating detection parameters for charging the battery cell in a constant pressure state using the second charging rate includes:

[0154] Obtaining the thickness change and charging capacity of the battery cell in a constant pressure state during charging at each preset sub-rate;

[0155] According to the thickness change and the charging capacity, the thickness capacity change corresponding to each preset sub-rate is determined.

[0156] In this embodiment, the second charging rate may include a plurality of preset sub-rates, wherein the plurality of preset sub-rates may refer to a plurality of charging rates used to charge the battery cell in the process of determining the lithium plating threshold.

[0157] like Figure 2 and Figure 3 As shown in FIG. 1 , the multiple preset sub-rates may be 0.33C, 0.5C, 0.7C and 1C. The thickness change and charging capacity corresponding to the multiple preset sub-rates may be obtained. During the charging process of the multiple preset sub-rates, the thickness change of the battery cell as the charging capacity changes may be as follows: Figure 2 The thickness-to-capacity ratio representing the ratio between the thickness change and the charging capacity of the battery cell corresponding to each preset sub-rate can be calculated.

[0158] It is also possible to calculate the thickness-capacity differential ratio of the ratio between the differential of the thickness change of the battery cell and the differential of the charging capacity corresponding to each preset sub-rate according to the thickness change and the charging capacity corresponding to the multiple preset sub-rates, and obtain the multiple thickness-capacity differential ratios corresponding to the multiple preset sub-rates, such as Figure 3 shown.

[0159] The thickness-capacity variation may include the above-mentioned thickness-capacity ratio or thickness-capacity differential ratio.

[0160] In this way, multiple preset sub-rates can be used for charging, so that the thickness capacity changes corresponding to the multiple preset sub-rates can be obtained. Subsequently, the thickness capacity changes corresponding to the multiple preset sub-rates can be used as the basis for determining the lithium plating threshold, thereby improving the reliability of the lithium plating threshold and further improving the accuracy of lithium plating detection.

[0161] In some embodiments, determining the lithium deposition threshold according to the lithium deposition detection parameter of charging the battery cell in a constant pressure state using the second charging rate includes:

[0162] The maximum value of the thickness capacity change corresponding to each preset sub-rate is determined as a candidate lithium precipitation threshold, and a plurality of candidate lithium precipitation thresholds are obtained;

[0163] The maximum value among multiple candidate lithium precipitation thresholds is determined as the lithium precipitation threshold.

[0164] In this embodiment, the battery cell can be charged at multiple preset sub-rates at which lithium deposition does not occur, so that the thickness capacity changes corresponding to the multiple preset sub-rates can be obtained. The maximum value of the thickness capacity change corresponding to each preset sub-rate can be first determined as a candidate lithium deposition threshold to obtain multiple candidate lithium deposition thresholds, and then the maximum value is selected from the multiple candidate lithium deposition thresholds as the final lithium deposition threshold.

[0165] In this way, the maximum value of the thickness capacity change corresponding to multiple preset sub-rates can be determined as the lithium plating threshold, further reducing the probability of misjudging non-lithium plating as lithium plating, and effectively improving the accuracy of lithium plating detection.

[0166] In some embodiments, the difference between the first sub-ratio and the second sub-ratio is greater than or equal to a preset difference threshold, wherein the first sub-ratio and the second sub-ratio are any two sub-ratios among a plurality of preset sub-ratios.

[0167] In this embodiment, it can be understood that for the selected multiple preset sub-rates, if the difference between two preset sub-rates is too small, such as 0.33C and 0.38C, the corresponding battery cell charging capacity and thickness change are very small during the charging process, and it does not play a role in more comprehensively reflecting the thickness change of the battery cell during the lithium ion embedding process. Based on this, for any two sub-rates in the multiple preset sub-rates, the difference can be greater than or equal to the preset difference threshold.

[0168] It is understandable that the preset difference threshold can be set according to actual needs. For example, the preset difference threshold can be 0.15~0.20C, which is not specifically limited here.

[0169] In this way, the difference between any two sub-rates is large, which can more comprehensively reflect the thickness capacity changes corresponding to different sub-rates, further improve the reliability of the lithium plating threshold, and effectively improve the accuracy of lithium plating detection.

[0170] In some embodiments, the first charging rate is greater than the second charging rate, and the second charging rate is a charging rate at which lithium plating does not occur in the battery cell.

[0171] In this embodiment, the second charging rate is used to determine the lithium precipitation threshold, so during the charging process, it is necessary to ensure that the thickness change of the battery cell is caused by ion embedding, so the second charging rate can use a smaller charging rate that does not cause lithium precipitation. The first charging rate is the charging rate used in the actual charging process. In order to improve the charging efficiency, the first charging rate generally uses a larger charging rate, so the first charging rate is greater than the second charging rate.

[0172] In this way, a more reasonable and accurate lithium deposition threshold value can be determined based on the thickness capacity change of the battery cell when charging the battery cell at the second charging rate at which lithium deposition will not occur, thereby further improving the accuracy of lithium deposition detection.

[0173] In some embodiments, when the battery cell is a soft-pack battery cell or a laminated battery cell, the preload force in the constant pressure state ranges from 30 kg to 100 kg;

[0174] When the battery cell is a hard shell battery cell, the preload force value range in the constant pressure state is greater than or equal to 300 kg.

[0175] In this embodiment, the preload force refers to a force applied in advance during the battery cell test in order to enhance the connection tightness between the battery cell structures and prevent the battery cell from being deformed due to external factors during use. In this embodiment, the battery cell can be placed in a constant pressure state by applying the preload force and then passing through a constant pressure device.

[0176] If the battery cell is a soft-pack battery cell or a laminated battery cell, excessive preload may damage the battery cell. Therefore, a kilogram force of 30kg to 100kg can be used as the preload, which can keep the battery cell under a constant pressure state of the preload.

[0177] If the battery cell is a hard shell battery cell, its bearing capacity is greatly improved, and a kilogram force greater than or equal to 300kg can be used as the preload force, so that the battery cell can be placed in a constant pressure state of the preload force to ensure a better constant pressure effect and further reduce the impact of changes in its thickness on changes in force.

[0178] In this way, for soft-pack batteries or laminated batteries, the preload force is between 30kg and 100kg, and for hard-shell batteries, the preload force can be greater than 300kg. This can ensure that the thickness change of the battery cell is less affected by the change of force under a constant pressure state, while avoiding the loss of the battery cell due to excessive preload force.

[0179] In some embodiments, performing lithium deposition detection on a battery cell according to a lithium deposition detection parameter and a lithium deposition threshold may include:

[0180] When the lithium deposition detection parameter is greater than the lithium deposition threshold, it is determined that lithium deposition occurs in the battery cell;

[0181] When the lithium deposition detection parameter is less than or equal to the lithium deposition threshold, it is determined that no lithium deposition occurs in the battery cell.

[0182] In this embodiment, the lithium deposition detection parameter can be compared with the lithium deposition threshold. If the lithium deposition detection parameter is greater than the lithium deposition threshold, it can be considered that the thickness change of the battery cell exceeds the thickness change caused by ion embedding, so it can be considered that lithium deposition occurs in the battery cell. If the lithium deposition detection parameter is less than or equal to the lithium deposition threshold, it can be considered that the thickness change of the battery cell is caused by ion embedding, that is, it can be considered that lithium deposition does not occur in the battery cell.

[0183] It can be understood that, when the lithium deposition detection parameter is a thickness-capacity differential ratio that characterizes the ratio between the differential of the thickness change and the differential of the charge capacity, performing lithium deposition detection on the battery cell according to the lithium deposition detection parameter and the lithium deposition threshold may include:

[0184] When the thickness-capacity differential ratio is greater than the lithium deposition threshold, it is determined that lithium deposition occurs in the battery cell;

[0185] When the thickness-capacity differential ratio is less than or equal to the lithium deposition threshold, it is determined that no lithium deposition occurs in the battery cell, wherein the lithium deposition threshold is a critical value of the thickness-capacity differential ratio when lithium deposition occurs in the battery cell.

[0186] It can also be understood that, when the lithium deposition detection parameter is a thickness-capacity ratio characterizing the ratio between the thickness change and the charging capacity, performing lithium deposition detection on the battery cell according to the lithium deposition detection parameter and the lithium deposition threshold may include:

[0187] When the thickness-to-capacity ratio is greater than the lithium deposition threshold, it is determined that lithium deposition occurs in the battery cell;

[0188] When the thickness-to-capacity ratio is less than or equal to the lithium deposition threshold, it is determined that no lithium deposition occurs in the battery cell, wherein the lithium deposition threshold is a critical value of the thickness-to-capacity ratio when lithium deposition occurs in the battery cell.

[0189] In this way, the lithium deposition detection parameters can be compared with the lithium deposition threshold value, and whether lithium deposition occurs in the battery cell can be accurately determined based on the comparison result.

[0190] In some embodiments, after performing lithium deposition detection based on the lithium deposition threshold, the method further includes:

[0191] When it is determined that lithium plating occurs in the battery cell, a target instruction is output, where the target instruction is used to instruct to reduce the first charging rate.

[0192] In this embodiment, the lithium deposition detection parameter is the thickness-capacity differential ratio dH / dQ, and the lithium deposition threshold K is the critical value of the thickness-capacity differential ratio when the battery cell produces lithium deposition. If dH / dQ>K, it can be determined that lithium deposition has occurred in the battery cell. At this time, a target instruction can be output, and the target instruction is sent to the charging device. The charging device can reduce the first charging rate of the battery cell so that the battery cell will no longer continue to deposit lithium during the charging process, thereby improving the problem that the battery cell will pierce the diaphragm after lithium deposition.

[0193] In this embodiment, when lithium deposition occurs in the battery cell, the first charging rate can be reduced to solve the lithium deposition problem, thereby effectively improving the problem of puncturing the diaphragm due to lithium deposition and causing battery failure.

[0194] Based on the lithium precipitation detection method provided in the above embodiment, Figure 4 A schematic flow chart of a specific scenario embodiment of a lithium deposition detection method is shown. The scenario embodiment may include the following steps:

[0195] Step 401, place the battery cell on the fixture, apply preload force through the fixture, and maintain a constant pressure state through a constant pressure device. For example, a Ni50 soft pack battery cell can be selected, the preload force of the fixture is 100Kg, confirm that the battery cell is at the force center of the fixture, and maintain a constant pressure state of the battery cell through the constant pressure device.

[0196] Step 402, obtain the thickness capacity change of the battery cell when charged at different preset sub-rates. For example, the battery cell is charged and discharged at a preset sub-rate, and the battery cell voltage, charging capacity, and thickness change are synchronously monitored. The charging rate can be 0.33C, 0.5C, 0.7C, and 1C. The battery cell will not deposit lithium when charged at this charging rate. The discharge rate is 1C+0.04C. It can be understood that the discharge rate can be determined according to actual needs and is not limited here. The charging capacity, thickness change, and expansion force data of the battery cell can be extracted first, and a graph is drawn with the charging capacity as the horizontal axis and the thickness change as the vertical axis. The result is as follows: Figure 2 Then we can draw a graph with the charge capacity (Q) as the horizontal axis and the thickness capacity differential ratio (DH / DQ) as the vertical axis. The result is as follows: Figure 3 shown.

[0197] Step 403, the maximum value of the thickness capacity change when charging at different preset sub-rates is used as the lithium deposition threshold. For example, the maximum value of DH / DQ under four charging rates can be selected as the lithium deposition threshold K.

[0198] Step 404 , during the actual charging process, monitor the thickness and capacity changes of the battery cell, and if the thickness and capacity changes exceed the lithium deposition threshold, determine that the battery cell has lithium deposition.

[0199] Based on the lithium deposition detection method provided in the above embodiment, the present application also provides an embodiment of a lithium deposition detection device.

[0200] Figure 5 A schematic structural diagram of a lithium deposition detection device provided in another embodiment of the present application is shown. For ease of explanation, only the parts related to the embodiment of the present application are shown.

[0201] Reference Figure 5 , the lithium deposition detection device 500 may include:

[0202] The charging module 501 is used to charge the battery cell using a first charging rate;

[0203] A first determination module 502 is used to determine a lithium deposition detection parameter of a battery cell charged at a first charge rate, wherein the lithium deposition detection parameter represents a change in thickness of the battery cell as a function of charging capacity;

[0204] The detection module 503 is used to perform lithium deposition detection on the battery cell according to the lithium deposition detection parameters and the lithium deposition threshold value; wherein the lithium deposition threshold value represents the critical value of the thickness change amount of the battery cell with the change of the charging capacity when lithium deposition occurs.

[0205] In this embodiment, the lithium deposition detection parameters of the battery cell charged at the first charging rate can be determined, and the battery cell is subjected to lithium deposition detection according to the lithium deposition detection parameters and the lithium deposition threshold, wherein the lithium deposition detection parameters can characterize the change in thickness of the battery cell with the change in charging capacity, that is, the change in thickness of the battery cell with the change in charging capacity can be compared with the lithium deposition threshold reflecting the change critical value, thereby determining whether lithium deposition occurs in the battery cell during the charging process. In this way, since the change in thickness of the battery cell with the change in charging capacity is mainly related to lithium deposition of the battery cell and is less affected by other external factors, this can be used as a basis for determining whether the battery cell has lithium deposition, which can effectively improve the accuracy of lithium deposition detection.

[0206] In some embodiments, the lithium deposition detection parameter includes a thickness-capacity differential ratio that characterizes the ratio between the differential of the thickness change of the battery cell and the differential of the charging capacity. The first determination module 502 may also be used to:

[0207] Obtaining a thickness change and a charging capacity of the battery cell when charged at a first charging rate;

[0208] The thickness-capacity differential ratio, which represents the ratio between the differential of the thickness change and the differential of the charging capacity, is used as a lithium plating detection parameter when the battery cell is charged at the first charging rate.

[0209] In this way, the thickness-capacity differential ratio, which is the ratio of the differential of the thickness change to the differential of the charging capacity, can be used as a lithium plating detection parameter for charging the battery cell at the first charging rate. That is, the thickness change under unit charging capacity can be used as a basis for judging whether the battery cell has lithium plating, which further reduces the influence of other external factors on the thickness change of the battery cell, making the judgment result more accurate and further improving the accuracy of lithium plating detection.

[0210] In some embodiments, the lithium plating detection parameter includes a thickness-to-capacity ratio that characterizes the ratio between the thickness change and the charging capacity of the battery cell. The first determination module 502 may also be used to:

[0211] Obtaining a thickness change and a charging capacity of the battery cell when charged at a first charging rate;

[0212] The thickness-to-capacity ratio, which characterizes the ratio between the thickness change and the charging capacity, is used as a lithium plating detection parameter when the battery cell is charged at the first charging rate.

[0213] In this way, the thickness-to-capacity ratio, which is the ratio between the thickness change and the charging capacity, can be used as a lithium plating detection parameter for charging the battery cell at the first charging rate. The thickness-to-capacity ratio is mainly related to the lithium plating of the battery cell and is not affected by the modulus of the battery cell, thereby reducing the error value of the lithium plating detection and improving the accuracy of the lithium plating detection.

[0214] In some embodiments, the lithium deposition detection device 500 may further include:

[0215] A second determination module is used to determine the lithium plating detection parameters for charging the battery cell in a constant pressure state using a second charging rate;

[0216] The third determination module is used to determine the lithium deposition threshold value according to the lithium deposition detection parameter of charging the battery cell in a constant pressure state using the second charging rate.

[0217] In this way, the battery cell can be charged at a second charging rate under a constant pressure state to determine the lithium deposition detection parameters corresponding to the second charging rate, and the lithium deposition detection parameters are less affected by the change in force. Therefore, an accurate lithium deposition threshold can be determined based on the lithium deposition detection parameters, and then lithium deposition detection can be performed based on the accurate lithium deposition threshold, thereby improving the accuracy of lithium deposition detection.

[0218] In some embodiments, the third determination module may also be used to:

[0219] Determining a thickness capacity change when charging the battery cell at a constant pressure state using a second charging rate;

[0220] The maximum value of the thickness capacity change is determined as the lithium plating threshold.

[0221] In this way, the maximum value of the thickness capacity change can be determined as the lithium deposition threshold, which can reduce the probability of misjudging non-lithium deposition as lithium deposition, and further improve the accuracy of lithium deposition detection.

[0222] In some embodiments, the second charging rate includes a plurality of preset sub-rates, and the second determining module may also be used to:

[0223] Obtaining the thickness change and charging capacity of the battery cell in a constant pressure state during charging at each preset sub-rate;

[0224] According to the thickness change and the charging capacity, the thickness capacity change corresponding to each preset sub-rate is determined.

[0225] In this way, multiple preset sub-rates can be used for charging, so that the thickness capacity changes corresponding to the multiple preset sub-rates can be obtained. Subsequently, the thickness capacity changes corresponding to the multiple preset sub-rates can be used as the basis for determining the lithium plating threshold, thereby improving the reliability of the lithium plating threshold and further improving the accuracy of lithium plating detection.

[0226] In some embodiments, the third determination module may also be used to:

[0227] The maximum value of the thickness capacity change corresponding to each preset sub-rate is determined as a candidate lithium precipitation threshold, and a plurality of candidate lithium precipitation thresholds are obtained;

[0228] The maximum value among multiple candidate lithium precipitation thresholds is determined as the lithium precipitation threshold.

[0229] In this way, the maximum value of the thickness capacity change corresponding to multiple preset sub-rates can be determined as the lithium plating threshold, further reducing the probability of misjudging non-lithium plating as lithium plating, and effectively improving the accuracy of lithium plating detection.

[0230] In some embodiments, the difference between the first sub-ratio and the second sub-ratio is greater than or equal to a preset difference threshold, wherein the first sub-ratio and the second sub-ratio are any two sub-ratios among a plurality of preset sub-ratios.

[0231] In this way, the difference between any two sub-rates is large, which can more comprehensively reflect the thickness capacity changes corresponding to different sub-rates, further improve the reliability of the lithium plating threshold, and effectively improve the accuracy of lithium plating detection.

[0232] In some embodiments, the first charging rate is greater than the second charging rate, and the second charging rate is a charging rate at which lithium plating does not occur in the battery cell.

[0233] In this way, a more reasonable and accurate lithium deposition threshold value can be determined based on the thickness capacity change of the battery cell when charging the battery cell at the second charging rate at which lithium deposition will not occur, thereby further improving the accuracy of lithium deposition detection.

[0234] In some embodiments, when the battery cell is a soft-pack battery cell or a laminated battery cell, the preload force in the constant pressure state ranges from 30 kg to 100 kg;

[0235] When the battery cell is a hard shell battery cell, the preload force value range in the constant pressure state is greater than or equal to 300 kg.

[0236] In this way, for soft-pack batteries or laminated batteries, the preload force is between 30kg and 100kg, and for hard-shell batteries, the preload force can be greater than 300kg. This can ensure that the thickness change of the battery cell is less affected by the change of force under a constant pressure state, while avoiding the loss of the battery cell due to excessive preload force.

[0237] In some embodiments, the detection module 503 may also be used to:

[0238] When the lithium deposition detection parameter is greater than the lithium deposition threshold, it is determined that lithium deposition occurs in the battery cell;

[0239] When the lithium deposition detection parameter is less than or equal to the lithium deposition threshold, it is determined that no lithium deposition occurs in the battery cell.

[0240] In this way, the lithium deposition detection parameters can be compared with the lithium deposition threshold value, and whether lithium deposition occurs in the battery cell can be accurately determined based on the comparison result.

[0241] In some embodiments, the lithium deposition detection device 500 may further include:

[0242] The output module is used to output a target instruction when it is determined that lithium plating occurs in the battery cell, and the target instruction is used to instruct to reduce the first charging rate.

[0243] In this embodiment, when lithium deposition occurs in the battery cell, the first charging rate can be reduced to solve the lithium deposition problem, thereby effectively improving the problem of puncturing the diaphragm due to lithium deposition and causing battery failure.

[0244] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of the present application, and are devices corresponding to the above-mentioned lithium plating detection method. All implementation methods in the above-mentioned method embodiment are applicable to the embodiments of the device. Its specific functions and the technical effects brought about can be specifically referred to the method embodiment part, which will not be repeated here.

[0245] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0246] An embodiment of the present application also provides a battery management system, which may include the above-mentioned lithium plating detection device.

[0247] like Figure 6As shown, BMS600 (Battery Management System) can be connected to a charging device 601 for charging the battery module and a sensor 602 installed in the battery module for communication. Among them, the charging device 601 can send the capacity information and voltage information of the battery cells in the battery module during the charging and discharging process to BMS600. Sensor 602 may include a strain sensor and a pressure sensor, which respectively send the strain information and pressure information of the battery cells in the battery module to BMS600. The thickness change of the battery cells in the battery module is determined according to the strain information. BMS600 can also calculate the ratio between the differential of the thickness change during the charging process and the differential of the charging capacity, that is, the thickness-capacity differential ratio dH / dQ, based on the combined capacity information, and compare the thickness-capacity differential ratio dH / dQ with the lithium precipitation threshold K, wherein the determination of the lithium precipitation threshold is as mentioned above and will not be repeated here.

[0248] If dH / dQ>K, it can be considered that lithium deposition occurs in the battery cells in the current battery module. At this time, the BMS600 can send a target instruction to the charging device 601 so that the charging device 601 can reduce the actual charging rate of the charging current.

[0249] An embodiment of the present application also provides a vehicle, which may include the above-mentioned battery management system.

[0250] Figure 7 A schematic diagram of the hardware structure of an electronic device provided in yet another embodiment of the present application is shown.

[0251] The electronic device 700 may include a processor 701 and a memory 702 storing programs or instructions. When the processor 701 executes the program, the steps in any of the above method embodiments are implemented.

[0252] Exemplarily, the program may be divided into one or more modules / units, one or more modules / units are stored in the memory 702 and executed by the processor 701 to complete the present application. One or more modules / units may be a series of program instruction segments capable of completing a specific function, and the instruction segments are used to describe the execution process of the program in the device.

[0253] Specifically, the processor 701 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

[0254] The memory 702 may include a large capacity memory for data or instructions. By way of example and not limitation, the memory 702 may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive or a combination of two or more of these. In appropriate cases, the memory 702 may include a removable or non-removable (or fixed) medium. In appropriate cases, the memory 702 may be inside or outside the integrated gateway disaster recovery device. In a specific embodiment, the memory 702 is a non-volatile solid-state memory.

[0255] The memory may include read-only memory (ROM), random access memory (RAM), magnetic disk storage media devices, optical storage media devices, flash memory devices, electrical, optical or other physical / tangible memory storage devices. Thus, typically, the memory includes one or more tangible (non-transitory) readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to an aspect of the present disclosure.

[0256] The processor 701 implements any one of the methods in the above embodiments by reading and executing the program or instruction stored in the memory 702 .

[0257] In one example, the electronic device may further include a communication interface 703 and a bus 704. The processor 701, the memory 702, and the communication interface 703 are connected via the bus 704 and communicate with each other.

[0258] The communication interface 703 is mainly used to implement communication between various modules, devices, units and / or equipment in the embodiments of the present application.

[0259] Bus 704 includes hardware, software or both, and the components of online data traffic billing equipment are coupled to each other. For example, but not limitation, the bus may include accelerated graphics port (AGP) or other graphics bus, enhanced industrial standard architecture (EISA) bus, front-side bus (FSB), hypertransport (HT) interconnection, industrial standard architecture (ISA) bus, infinite bandwidth interconnection, low pin count (LPC) bus, memory bus, micro channel architecture (MCA) bus, peripheral component interconnect (PCI) bus, PCI-Express (PCI-X) bus, serial advanced technology attachment (SATA) bus, video electronics standard association local (VLB) bus or other suitable bus or two or more of these combinations. Where appropriate, bus 704 may include one or more buses. Although the present application embodiment describes and shows a specific bus, the present application considers any suitable bus or interconnection.

[0260] In addition, in combination with the method in the above embodiment, the embodiment of the present application may provide a machine-readable storage medium for implementation. The machine-readable storage medium stores a program or instruction; when the program or instruction is executed by a processor, any one of the methods in the above embodiment is implemented. The machine-readable storage medium can be read by a machine such as a computer.

[0261] An embodiment of the present application further provides a chip, which includes a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run programs or instructions to implement the various processes of the above-mentioned method embodiment, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0262] It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0263] An embodiment of the present application provides a computer program product, which is stored in a machine-readable storage medium. The program product is executed by at least one processor to implement the various processes of the above-mentioned method embodiment and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0264] It should be clear that the present application is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present application is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present application.

[0265] The functional modules shown in the structural block diagram described above can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application-specific integrated circuit (ASIC), appropriate firmware, a plug-in, a function card, etc. When implemented in software, the elements of the present application are programs or code segments used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link by a data signal carried in a carrier. "Machine-readable medium" may include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROMs, flash memories, erasable ROMs (EROMs), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segment can be downloaded via a computer grid such as the Internet, an intranet, etc.

[0266] It should also be noted that the exemplary embodiments mentioned in this application describe some methods or systems based on a series of steps or devices. However, this application is not limited to the order of the above steps, that is, the steps can be performed in the order mentioned in the embodiment, or in a different order from the embodiment, or several steps can be performed simultaneously.

[0267] Aspects of the present disclosure are described above with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and program products according to the embodiments of the present disclosure. It should be understood that each box in the flowchart and / or block diagram and the combination of each box in the flowchart and / or block diagram can be implemented by a computer program or instruction. These programs or instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine so that these instructions executed by the processor of the computer or other programmable data processing device enable the implementation of the functions / actions specified in one or more boxes of the flowchart and / or block diagram. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field programmable logic circuit. It can also be understood that each box in the block diagram and / or flowchart and the combination of boxes in the block diagram and / or flowchart can also be implemented by dedicated hardware that performs the specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0268] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A lithium precipitation detection method, characterized in that: include: Charging the battery cell using a first charging rate; Determining a lithium plating detection parameter of the battery cell when charging at the first charging rate, wherein the lithium plating detection parameter represents a change in thickness of the battery cell as a function of charging capacity; The battery cell is subjected to a lithium deposition detection according to the lithium deposition detection parameter and the lithium deposition threshold; wherein the lithium deposition threshold represents a critical value of the thickness variation with the change of the charging capacity when the battery cell produces lithium deposition; The method further comprises: Determining the lithium plating detection parameter for charging the battery cell in a constant pressure state using a second charging rate; Determining the lithium deposition threshold value according to the lithium deposition detection parameter of charging the battery cell in a constant pressure state using a second charging rate; The second charging rate includes a plurality of preset sub-rates, and the lithium plating detection parameter for charging the battery cell in a constant pressure state using the second charging rate includes: Obtaining a thickness change and a charging capacity of the battery cell in a constant pressure state during charging at each of the preset sub-rates; Determine the thickness capacity change corresponding to each of the preset sub-rates according to the thickness change and the charging capacity, and obtain the thickness capacity changes corresponding to the multiple preset sub-rates; The lithium plating threshold is determined according to the thickness capacity changes corresponding to the multiple preset sub-rates.

2. The method according to claim 1, characterized in that The lithium deposition detection parameter includes a thickness-capacity differential ratio that characterizes the ratio between the differential of the thickness change of the battery cell and the differential of the charging capacity. The lithium deposition detection parameter for determining the battery cell to be charged at the first charging rate includes: Obtaining the thickness change and the charging capacity of the battery cell when charged at the first charging rate; A thickness-capacity differential ratio, which characterizes the ratio between the differential of the thickness change and the differential of the charging capacity, is used as a lithium plating detection parameter when the battery cell is charged at the first charging rate.

3. The method according to claim 1, characterized in that The lithium deposition detection parameter includes a thickness-to-capacity ratio characterizing a ratio between a thickness change of the battery cell and the charging capacity, and the lithium deposition detection parameter for determining that the battery cell is charged at the first charging rate includes: Obtaining the thickness change and the charging capacity of the battery cell when charged at the first charging rate; The thickness-to-capacity ratio, which characterizes the ratio between the thickness variation and the charging capacity, is used as a lithium plating detection parameter when the battery cell is charged at the first charging rate.

4. The method according to claim 1, characterized in that The step of determining the lithium deposition threshold according to the lithium deposition detection parameter of charging the battery cell in a constant pressure state using a second charging rate includes: Determine the maximum value of the thickness capacity change corresponding to each of the preset sub-rates as a candidate lithium precipitation threshold value, and obtain a plurality of candidate lithium precipitation threshold values; The maximum value among the multiple candidate lithium precipitation thresholds is determined as the lithium precipitation threshold.

5. The method according to claim 1, characterized in that The difference between the first sub-ratio and the second sub-ratio is greater than or equal to a preset difference threshold, wherein the first sub-ratio and the second sub-ratio are any two sub-ratios among the plurality of preset sub-ratios.

6. The method according to claim 1, characterized in that The first charging rate is greater than the second charging rate, and the second charging rate is a charging rate at which lithium plating does not occur in the battery cell.

7. The method according to claim 1, characterized in that When the battery cell is a soft-pack battery cell or a laminated battery cell, the preload force in the constant pressure state ranges from 30kg to 100kg; When the battery cell is a hard shell battery cell, the preload force in the constant pressure state has a value range greater than or equal to 300 kg.

8. The method according to any one of claims 1 to 7, characterized in that The performing lithium deposition detection on the battery cell according to the lithium deposition detection parameter and the lithium deposition threshold comprises: When the lithium deposition detection parameter is greater than the lithium deposition threshold, determining that lithium deposition occurs in the battery cell; When the lithium deposition detection parameter is less than or equal to the lithium deposition threshold, it is determined that no lithium deposition occurs in the battery cell.

9. The method according to claim 8, characterized in that The method further comprises: When it is determined that lithium plating occurs in the battery cell, a target instruction is output, where the target instruction is used to instruct to reduce the first charging rate.

10. A lithium deposition detection device, characterized in that: include: A charging module, used to charge the battery cell using a first charging rate; A first determination module is used to determine a lithium deposition detection parameter of the battery cell when the battery cell is charged at the first charge rate, wherein the lithium deposition detection parameter represents a change in thickness of the battery cell as a function of charging capacity; A detection module, used for performing lithium deposition detection on the battery cell according to the lithium deposition detection parameter and the lithium deposition threshold; wherein the lithium deposition threshold represents a critical value of the thickness change amount with the change of the charging capacity when lithium deposition occurs in the battery cell; The device also includes: A second determination module, used to determine the lithium plating detection parameter for charging the battery cell in a constant pressure state using a second charging rate; A third determination module is used to determine the lithium deposition threshold according to the lithium deposition detection parameter of charging the battery cell in a constant pressure state using a second charging rate; The second charging rate includes a plurality of preset sub-rates, and the second determining module is further configured to: Obtaining a thickness change and a charging capacity of the battery cell in a constant pressure state during charging at each of the preset sub-rates; Determine the thickness capacity change corresponding to each of the preset sub-rates according to the thickness change and the charging capacity, and obtain the thickness capacity changes corresponding to the multiple preset sub-rates; The third determining module is further used for: The lithium plating threshold is determined according to the thickness capacity changes corresponding to the multiple preset sub-rates.

11. A battery management system, characterized in that: It comprises the lithium precipitation detection device as claimed in claim 10.

12. A vehicle, characterized in that: Comprising the battery management system as claimed in claim 11.

13. An electronic device, characterized in that: The device comprises: a processor and a memory storing programs or instructions; When the processor executes the program or instruction, the method according to any one of claims 1 to 9 is implemented.

14. A machine-readable storage medium, characterized in that: The machine-readable storage medium stores a program or instruction, and when the program or instruction is executed by a processor, the method according to any one of claims 1 to 9 is implemented.

15. A computer program product, characterized in that When the instructions in the computer program product are executed by a processor of an electronic device, the electronic device executes the method according to any one of claims 1 to 9.

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