Battery lithium precipitation state determination method, device, equipment, medium and program product

Abstract

This application provides a method, apparatus, device, medium, and program product for determining the lithium plating state of a battery, including: determining the internal resistance change state corresponding to the internal resistance of the lithium battery; and determining the lithium plating state of the lithium battery based on a first correlation relationship and the internal resistance change state; wherein the first correlation relationship includes a corresponding mapping relationship between the internal resistance change state and the lithium plating state. This application enables flexible determination of the lithium plating state of a lithium battery at any stage of its life cycle.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, and in particular to a method, apparatus, equipment, medium and procedure for determining the lithium plating state of a battery. Background Technology

[0002] The state of lithium plating in a lithium-ion battery has a direct and significant impact on its capacity and safety. Therefore, determining the state of lithium plating is crucial for the safe use of the battery. Related technologies provide solutions for determining the amount of lithium plating within a single charging cycle. However, these solutions cannot flexibly determine the state of lithium plating at any stage of the battery's lifespan. Summary of the Invention

[0003] Based on the above technical problems, this application provides a method, apparatus, device, medium, and program product for determining the lithium plating state of a battery, which can flexibly determine the lithium plating state of a lithium battery at any stage of its life cycle.

[0004] The technical solution of this application embodiment is implemented as follows:

[0005] This application provides a method for determining the lithium plating state of a battery, the method comprising:

[0006] Determine the internal resistance change state corresponding to the internal resistance of the lithium battery.

[0007] Based on the first correlation and the internal resistance change state, the lithium plating state of the lithium battery is determined; wherein, the first correlation includes at least the corresponding mapping relationship between the internal resistance change state and the lithium plating state.

[0008] In some embodiments, the internal resistance change state includes at least the internal resistance deviation of the lithium battery; the internal resistance deviation includes the deviation between the expected internal resistance of the lithium battery and the battery internal resistance; determining the lithium plating state of the lithium battery based on the first correlation and the internal resistance change state includes:

[0009] If the internal resistance deviation is greater than the first threshold, the lithium plating state of the battery is determined based on the first correlation and the internal resistance change state.

[0010] In some embodiments, the internal resistance deviation is determined in the following manner:

[0011] Based on the number of battery cycles of the lithium battery and the second correlation, the expected internal resistance of the lithium battery is determined; wherein, the second correlation includes the mapping relationship between the battery internal resistance and the number of battery cycles.

[0012] The internal resistance deviation is determined based on the expected internal resistance and the battery internal resistance.

[0013] In some embodiments, the first association is obtained in the following manner:

[0014] Determine the set of internal resistance change states corresponding to the battery set; wherein, the battery set includes multiple lithium batteries with an aging degree greater than or equal to a degree threshold;

[0015] Determine the set of lithium plating amounts corresponding to the battery set;

[0016] Quantify the amount of lithium plating in the set of battery lithium plating amounts to obtain a set of battery lithium plating states;

[0017] The first association relationship is obtained by associating the internal resistance change states in the set of internal resistance change states with the battery lithium plating states in the set of battery lithium plating states.

[0018] In some embodiments, the lithium plating state of the battery is at least associated with the amount of lithium plating in the lithium battery; the method further includes:

[0019] If the amount of lithium plating in the battery is greater than or equal to the second threshold and less than the third threshold, the lithium plating state of the battery is determined to be a first risk state.

[0020] The output includes at least a first warning message for the first risk state, to at least trigger a reduction in the charging current of the lithium battery.

[0021] In some embodiments, the lithium plating state of the battery is at least associated with the amount of lithium plating in the lithium battery; the method further includes:

[0022] If the amount of lithium plating in the battery is greater than or equal to a third threshold, the lithium plating state of the battery is determined to be a second risk state; wherein, the risk level of the second risk state is greater than the risk level of the first risk state;

[0023] The output includes at least a second warning message indicating the second risk state, to trigger a reduction in the upper limit of the lithium battery's state of charge (SOC).

[0024] In some embodiments, the method further includes:

[0025] Determine the charging cutoff voltage of the lithium battery;

[0026] After the charging process of the lithium battery is completed, the resting voltage of the lithium battery is determined;

[0027] The internal resistance of the battery is determined based on the charging cutoff voltage and the resting voltage.

[0028] This application embodiment also provides a battery lithium plating state determination device, the battery lithium plating state determination device comprising:

[0029] A determining module is used to determine the internal resistance change state corresponding to the internal resistance of the lithium battery; and to determine the lithium plating state of the lithium battery based on a first correlation relationship and the internal resistance change state; wherein, the first correlation relationship includes at least a mapping relationship between the internal resistance change state and the lithium plating state.

[0030] This application also provides an electronic device, which includes a processor and a memory; the memory stores a computer program; when the computer program is executed by the processor, it can implement the battery lithium plating state determination method as described above.

[0031] This application also provides a computer-readable storage medium storing a computer program; when the computer program is executed by a processor of an electronic device, it can implement the battery lithium plating state determination method as described above.

[0032] This application also provides a computer program product, which includes a computer program; when the computer program is executed by the processor of an electronic device, it can implement the battery lithium plating state determination method as described above.

[0033] The lithium plating state determination method provided in this application determines the lithium battery's lithium plating state based on a first correlation relationship and the internal resistance change state of the battery. This method allows for flexible determination of the lithium battery's lithium plating state over the entire lifespan of the lithium battery. Furthermore, since the first correlation relationship includes a mapping between the internal resistance change state and the lithium plating state, the accuracy of the lithium plating state is improved. This method enables the lithium battery's lithium plating state to be determined flexibly and accurately at any time. Attached Figure Description

[0034] Figure 1 A flowchart illustrating the battery lithium plating state determination method provided in this application embodiment;

[0035] Figure 2 This is a schematic diagram illustrating the change of battery internal resistance with the number of battery cycles, provided in an embodiment of this application.

[0036] Figure 3 A statistical schematic diagram of the internal resistance of a lithium battery in a lithium plating state, provided for an embodiment of this application;

[0037] Figure 4A schematic diagram illustrating the principle of determining the amount of lithium plating in a battery and the risk level, provided for embodiments of this application;

[0038] Figure 5 A schematic diagram illustrating the changes in resting voltage and charging cutoff voltage provided in an embodiment of this application;

[0039] Figure 6 A schematic diagram of the battery lithium plating status early warning provided in the embodiments of this application;

[0040] Figure 7 This is a schematic diagram of the battery lithium plating state determination device provided in the embodiments of this application;

[0041] Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0043] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0044] In the following description, the terms "first" and "second" are used merely to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first" and "second" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0045] In this application embodiment, the terms "module" or "unit" refer to a computer program or part of a computer program that has a predetermined function and works with other related parts to achieve a predetermined goal, and can be implemented wholly or partially using software, hardware (such as processing circuitry or memory), or a combination thereof. Similarly, a processor (or multiple processors or memory) can be used to implement one or more modules or units. Furthermore, each module or unit can be part of an overall module or unit that includes the functionality of that module or unit.

[0046] Unless otherwise defined, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in the embodiments of this application is for the purpose of describing the embodiments of this application only and is not intended to limit this application.

[0047] Before providing a further detailed description of the embodiments of this application, the nouns and terms involved in the embodiments of this application will be explained, and the nouns and terms involved in the embodiments of this application shall be interpreted as follows.

[0048] 1) Battery internal resistance: refers to the resistance encountered when current flows through the battery during operation. It includes ohmic internal resistance and polarization internal resistance. Polarization internal resistance includes electrochemical polarization internal resistance and concentration polarization internal resistance.

[0049] 2) Lithium deposition in the battery: This refers to the amount of lithium ions deposited as metallic lithium on the surface of the negative electrode during the charging process of a lithium-ion battery. Lithium deposition can lead to a decrease in battery performance and capacity, and may also cause safety issues.

[0050] 3) Cycle count: This refers to the number of times a battery completes a full charge-discharge cycle, from fully charged to completely discharged and then fully charged again. Cycle count is one of the important indicators for measuring battery life and durability.

[0051] When lithium batteries are charged under conditions such as low temperature and high current, lithium plating is prone to occur at the negative electrode. Lithium plating leads to a decrease in the usable capacity of the lithium battery, and severe lithium plating can induce safety problems. Therefore, testing the amount of lithium plating in lithium batteries is of great significance for the safe use of lithium batteries.

[0052] Lithium plating detection methods in related technologies are mainly used to detect lithium plating in a single charging cycle of a lithium battery. For example, by detecting the resting voltage of the lithium battery after charging, if a voltage plateau indicating lithium plating re-intercalation is detected on the resting voltage curve, it can be determined that lithium plating has occurred in the lithium battery. However, the above methods cannot achieve flexible detection of the amount of lithium plating in a lithium-ion battery throughout its entire life cycle.

[0053] Based on the above technical problems, embodiments of this application provide a method, apparatus, device, medium, and program product for determining the lithium plating state of a battery.

[0054] Figure 1 This is a flowchart illustrating the battery lithium plating state determination method provided in the embodiments of this application, as shown below. Figure 1 As shown, the process may include the following steps:

[0055] S101. Determine the internal resistance change state corresponding to the internal resistance of the lithium battery.

[0056] In one implementation, lithium batteries can be used to provide power for new energy vehicles.

[0057] In one implementation, the battery internal resistance may include the internal resistance value of the lithium battery at the current moment.

[0058] In one embodiment, the battery internal resistance may include the internal resistance value of the lithium battery when it is not in a charging state.

[0059] In one implementation, the battery internal resistance can be determined in the following way:

[0060] When the lithium battery is in a static state, the voltage and current of the circuit containing the lithium battery are detected, and the internal resistance of the battery is determined based on the amplitude of the voltage and the amplitude of the current.

[0061] In one embodiment, the internal resistance change state may include the change in the internal resistance of the lithium battery from a historical time to the current time, and may also include the change in the internal resistance of the battery at the current time relative to the target internal resistance; wherein, the target internal resistance may include the internal resistance that the lithium battery should have in the state of no lithium plating.

[0062] S102. Based on the first correlation relationship and the internal resistance change state, determine the lithium plating state of the lithium battery.

[0063] The first correlation includes at least the mapping relationship between the internal resistance change state and the lithium plating state of the battery.

[0064] In one embodiment, the lithium plating state of the battery determined by the above method can represent the severity of the lithium plating state of the lithium battery at the current moment.

[0065] In one embodiment, the first correlation may include a one-to-one correspondence between the internal resistance change state of the battery internal resistance relative to the target internal resistance obtained at time k and the lithium plating state of the battery at time k; wherein k can be an integer greater than or equal to 1.

[0066] In one implementation, the first correlation can be represented in the form of a function or a table. The internal resistance change state in the first correlation can be the independent variable in the function or table, and the lithium plating state of the battery in the first correlation can be the dependent variable corresponding to the internal resistance change state in the first correlation. That is, the internal resistance change state and the lithium plating state in the first correlation are not used to characterize specific values, but are used to characterize the change process of the lithium plating state of the lithium battery with its internal resistance change state in a continuous or discrete form over a wider range.

[0067] In one implementation, the first association can be predetermined.

[0068] In one implementation, the first association can be predetermined in the following manner:

[0069] The lithium plating state of lithium batteries in multiple sets of lithium batteries with different aging levels and different lithium plating states is determined. At the same time, the internal resistance change state of lithium batteries in the lithium battery sets is determined. Then, according to the identification of lithium batteries in the lithium battery sets, the correlation between different lithium plating states and internal resistance change states is established, thereby obtaining the first correlation relationship.

[0070] In one approach, the lithium plating state of a battery can represent the severity of lithium plating at a given moment; for example, the lithium plating state can include a slight lithium plating state, a significant lithium plating state, and a severe lithium plating state.

[0071] In one implementation, the lithium plating state of the battery can be determined in the following way:

[0072] The internal resistance change state that matches the internal resistance change state of the lithium battery in the first correlation relationship is determined as the first target change state, and the lithium plating state of the battery corresponding to the first target change state in the first correlation relationship is determined as the actual lithium plating state of the lithium battery.

[0073] In one implementation, a pre-established correspondence can be established between the amount of lithium plating in the battery and the state of lithium plating in the battery. Thus, after determining the amount of lithium plating in the battery at the current moment, the state of lithium plating in the battery corresponding to the amount of lithium plating can be determined from the above correspondence based on the matching relationship between the amount of lithium plating in the battery and the amount of lithium plating in the correspondence, and this state is determined as the actual state of lithium plating in the lithium battery.

[0074] In one implementation, the amount of lithium plating in the battery can be determined in the following way:

[0075] Based on the matching relationship between the internal resistance change state corresponding to the battery's internal resistance and the internal resistance change state in the third correlation, the second target change state is determined from the third correlation, and the amount of lithium plating in the battery corresponding to the second target change state in the third correlation is determined as the amount of lithium plating in the lithium battery; wherein, the second target change state may include the internal resistance change state that matches the internal resistance change state of the lithium battery in the third correlation, and the third correlation may include the mapping relationship between the amount of lithium plating in the battery and the internal resistance change state.

[0076] As can be seen from the above, the battery lithium plating state determination method provided in this application determines the internal resistance change state corresponding to the internal resistance of the lithium battery, and then determines the lithium plating state of the lithium battery based on the first correlation relationship and the internal resistance change state corresponding to the internal resistance. Thus, the lithium plating state of the lithium battery can be flexibly determined within the entire life cycle of the lithium battery. Furthermore, since the first correlation relationship includes the corresponding mapping relationship between the internal resistance change state and the lithium plating state, the accuracy of the lithium plating state can be improved. Through the above method, the lithium plating state of the lithium battery at any time can be determined flexibly and accurately.

[0077] Based on the foregoing embodiments, in the battery lithium plating state determination method provided in this application embodiment, the internal resistance change state includes the internal resistance deviation of the lithium battery; the internal resistance deviation includes the deviation between the expected internal resistance of the lithium battery and the battery internal resistance.

[0078] Accordingly, based on the first correlation and the internal resistance change state, the lithium plating state of the lithium battery can be determined in the following way:

[0079] If the internal resistance deviation is greater than the first threshold, the lithium plating state of the lithium battery is determined based on the first correlation and the internal resistance change state.

[0080] Accordingly, if the internal resistance deviation is less than or equal to the first threshold, the operation of determining the lithium plating state of the battery can be omitted.

[0081] In one embodiment, the expected internal resistance may include the resistance value that a lithium battery should have when it is not lithium-plated.

[0082] In one implementation, if the internal resistance deviation is greater than a first threshold and the internal resistance deviation shows an increasing trend, the lithium plating state of the battery can also be determined based on the first correlation and the internal resistance change state.

[0083] In one implementation, the first threshold may include 4% of the expected internal resistance.

[0084] As can be seen from the above, in the battery lithium plating state determination method provided in this application embodiment, if the internal resistance deviation is greater than a first threshold, the lithium battery lithium plating state is determined based on the first correlation relationship and the internal resistance change state. The internal resistance deviation includes the deviation between the expected internal resistance of the lithium battery and the battery's internal resistance. Thus, through the above method, not only is control over the operation of determining the lithium battery lithium plating state achieved, but also, by associating the deviation between the expected internal resistance of the lithium battery and the battery's internal resistance with the determination of the lithium battery lithium plating state, the first correlation relationship between the lithium battery lithium plating state and the lithium battery internal resistance change state can be fully utilized, and the accuracy of determining the lithium battery lithium plating state can be improved.

[0085] Based on the foregoing embodiments, the internal resistance deviation in the battery lithium plating state determination method provided in this application embodiment can be determined in the following way:

[0086] Based on the number of battery cycles and the second correlation, the expected internal resistance of the lithium battery is determined; based on the expected internal resistance and the battery internal resistance, the internal resistance deviation is determined.

[0087] The second correlation includes the mapping relationship between battery internal resistance and battery cycle number.

[0088] It should be noted that the operation of determining the expected internal resistance can be performed before the step of determining the lithium plating state of the battery.

[0089] In one implementation, the expected internal resistance may include the state or range that the internal resistance of the lithium battery should have in the unplated lithium state; for example, the expected internal resistance may be the target internal resistance in the foregoing embodiments.

[0090] In one implementation, the expected internal resistance can gradually change with the usage time of the lithium battery; for example, the expected internal resistance can increase with the extension of the usage time of the lithium battery and the increase of the battery cycle number. Therefore, the expected internal resistance of the lithium battery at the current moment can be determined based on the usage time of the lithium battery.

[0091] In one implementation, the internal resistance deviation may include the absolute value of the difference between the expected internal resistance and the current battery internal resistance.

[0092] In one implementation, the battery cycle count may include the number of cycles corresponding to the end of the last charging process of the lithium battery.

[0093] In one implementation, the second association can be established in advance.

[0094] In one implementation, the second correlation can be presented in the form of a table or function, showing the change of battery internal resistance as the number of battery cycles increases. That is, the number of battery cycles in the second correlation can be the independent variable, and the battery internal resistance in the second correlation can be the dependent variable corresponding to the number of battery cycles in the second correlation. In other words, the number of battery cycles and the battery internal resistance in the second correlation are not limited to a specific value, but are variables that can vary within at least a relatively wide range.

[0095] In practical applications, the increase in the internal resistance of lithium batteries mainly depends on two factors: First, the loss of positive / negative electrode materials due to aging during use and the growth of the solid electrolyte interface membrane (SEI) film; Second, lithium plating occurs during the charging process. For example, during charging, metallic lithium in the lithium battery reacts with the electrolyte to generate reaction products that continuously thicken the SEI film. At the same time, metallic lithium continuously deposits on the surface of the negative electrode, hindering the liquid phase diffusion process and leading to an additional increase in the battery's internal resistance.

[0096] Meanwhile, during the natural aging process of lithium batteries, the internal resistance of the battery generally shows a linear increasing trend with the increase of the number of charge and discharge cycles. However, if lithium plating occurs in the lithium battery, its internal resistance will increase additionally, causing the growth trend of the battery internal resistance to deviate from the linear relationship.

[0097] Figure 2 This is a schematic diagram illustrating the change in battery internal resistance with battery cycle number provided in an embodiment of this application, as shown below. Figure 2 In the two-dimensional coordinate system shown, the horizontal axis represents the number of battery cycles, and the vertical axis represents the battery's internal resistance. From Figure 2 It can be seen that the battery internal resistance increases linearly with the increase of battery cycle number; for example, Figure 2 The battery internal resistance variation model shown can be called the standard internal resistance growth model; for example, Figure 2 The linear curve shown can be a functional representation of the second correlation.

[0098] In the case of lithium batteries being used to provide power for new energy vehicles, the standard model for the growth of internal resistance can include the relationship between the internal resistance of the lithium battery and characteristic parameters such as the number of battery cycles, the mileage of the vehicle associated with the lithium battery, and the driving time, in the state where the lithium battery has not deposited lithium. The state where the lithium battery has not deposited lithium can correspond to the state where the number of battery cycles is less than the number of cycles threshold or the mileage of the vehicle is less than the mileage threshold.

[0099] Therefore, it can be done Figure 2 The method shown can predict the internal resistance of a lithium battery after a single charge-discharge cycle, i.e., the expected internal resistance. At the same time, by tracking the correspondence between the number of battery cycles and the internal resistance, a second correlation between the number of battery cycles and the internal resistance can be established. Thus, through the second correlation and the dynamically changing number of battery cycles, the expected internal resistance of the lithium battery can be flexibly tracked and predicted.

[0100] For example, by means of Figure 2By fitting the relationship between the battery cycle count and the battery internal resistance shown, a second correlation can be obtained; for example, the second correlation can be fitted by linear fitting, polynomial fitting, and exponential fitting.

[0101] Correspondingly, for lithium batteries in the lithium plating state, their internal resistance is relative to... Figure 2 The trends in internal resistance shown may differ. Figure 3 This is a statistical schematic diagram of the internal resistance of a lithium battery in a lithium plating state, provided in an embodiment of this application. Figure 3 In the coordinate system shown, as the number of battery cycles increases, or operations such as low-temperature charging and high-current charging are performed, after the number of battery cycles exceeds 800, the internal resistance of the lithium battery exhibits a step change, thus causing the internal resistance of the lithium battery to... Figure 2 The expected internal resistances corresponding to the second correlation shown show a deviation in internal resistance; at the same time, the static voltage curve of the lithium battery also shows a voltage plateau for lithium plating and re-intercalation.

[0102] As can be seen from the above, the battery lithium plating state determination method provided in this application determines the expected internal resistance of the lithium battery based on the battery cycle count and a second correlation, whereby the second correlation includes a mapping relationship between the battery internal resistance and the battery cycle count. Thus, this method not only improves the accuracy of the expected internal resistance of the lithium battery but also enables flexible determination of the expected internal resistance for any lifespan of the lithium battery, and provides data support for determining internal resistance deviations.

[0103] Based on the foregoing embodiments, the first correlation relationship in the battery lithium plating state determination method provided in this application is obtained in the following way:

[0104] SA1. Determine the set of internal resistance change states corresponding to the battery set.

[0105] The battery set includes multiple lithium batteries with an aging level greater than or equal to a threshold.

[0106] In one implementation, the lithium batteries in the battery pack may already be in a state of lithium metal deposition; for example, the amount of lithium metal deposited by each lithium battery in the battery pack may be different.

[0107] In one implementation, the internal resistance of the nth lithium battery in the battery pack can be determined in the following way:

[0108] Establish a circuit loop for detecting the internal resistance of the battery, and connect the nth lithium battery to the circuit loop. Then, detect the current and voltage data in the circuit loop, and determine the internal resistance of the nth lithium battery based on the current and voltage data. Here, n can be any integer greater than or equal to 1 and less than or equal to N; N can be an integer greater than 2 and can represent the number of lithium batteries contained in the battery set.

[0109] In one implementation, after determining the internal resistance of all lithium batteries in the battery set using the above method to obtain the internal resistance set, the internal resistance change state of each lithium battery can be determined based on the internal resistance deviation between the internal resistance of each lithium battery in the internal resistance set and its expected internal resistance. Then, the internal resistance change states of all lithium batteries in the battery set are integrated to obtain the internal resistance change state set.

[0110] SA2, Determine the set of lithium plating amounts corresponding to the battery set.

[0111] In one implementation, the amount of lithium plating in the nth lithium battery in the battery set can be determined in the following way:

[0112] The nth lithium battery in the lithium battery assembly is disassembled at 0% SOC. Experimental conditions are set to trigger the reaction of the negative electrode lithium-plating plates at different positions of the nth lithium battery with anhydrous ethanol. The volume of hydrogen gas produced during the reaction is measured. Then, based on the volume of hydrogen gas and the reaction molar ratio, the average amount of lithium plating per negative electrode plate in the nth lithium battery is calculated. Finally, the amount of lithium plating in the nth lithium battery is calculated based on the number of negative electrode plates in the nth lithium battery.

[0113] For example, after obtaining the lithium plating amount of all lithium batteries in the battery set using the above method, the lithium plating amount set of all lithium batteries in the battery set can be obtained by integrating the lithium plating amounts of all lithium batteries in the battery set.

[0114] SA3 quantifies the amount of lithium plating in the set of lithium plating amounts of batteries, and obtains the set of lithium plating states of batteries.

[0115] In one implementation, the battery lithium plating state set may include multiple different levels of battery lithium plating states.

[0116] In one implementation, the set of battery lithium plating states can be obtained in the following way:

[0117] A threshold set is determined, and then the lithium plating amount in the lithium plating amount set is quantified according to the relationship between the thresholds in the threshold set and the lithium plating amount in the lithium plating amount set, to obtain the lithium plating amount set. For example, if the lithium plating amount of the m-th battery in the lithium plating amount set is greater than the second threshold but less than the third threshold, the lithium plating amount of the m-th battery can be quantified as the first risk state. If the lithium plating amount of the m-th battery is greater than the third threshold, the lithium plating amount of the m-th battery can be quantified as the second risk state. Here, m is an integer greater than or equal to 1, and the threshold set can include the second threshold and the third threshold.

[0118] SA4, by associating the internal resistance change states in the set of associated internal resistance change states with the lithium plating states in the set of associated lithium plating states, obtains the first association relationship.

[0119] In one implementation, the first association can be obtained in the following way:

[0120] By associating the internal resistance change state of the nth lithium battery with its lithium plating state in the set of associated internal resistance change states, the correspondence between the internal resistance change state of the nth lithium battery and its lithium plating state is obtained. The above correspondence between each lithium battery in the set of associated internal resistance change states is then integrated to obtain the first correlation relationship.

[0121] As can be seen from the above, in the battery lithium plating state determination method provided in this application embodiment, after determining the internal resistance change state set and the battery lithium plating state set corresponding to the battery set, the amount of lithium plating in the battery lithium plating quantity set is quantified to obtain the battery lithium plating state set, realizing the tracking quantification of the amount of lithium plating in the battery lithium plating quantity set; and, through the battery lithium plating state set, the lithium plating risk of lithium batteries can also be displayed in a concise and intuitive way; on this basis, the internal resistance change state in the internal resistance change state set and the battery lithium plating state in the battery lithium plating state set are correlated, and the battery set includes multiple lithium batteries with an aging degree greater than or equal to the degree threshold, which can not only improve the richness of the data in the first correlation relationship, but also improve the correlation between the battery lithium plating state and the internal resistance change state, thereby improving the accuracy of the first correlation relationship.

[0122] Based on the foregoing embodiments, in the battery lithium plating state determination method provided in this application embodiment, the battery lithium plating state is at least related to the amount of lithium plating in the lithium battery.

[0123] In one implementation, both the internal resistance change state and the battery lithium plating state can be associated with the amount of battery lithium plating; for example, the internal resistance deviation characterized by the internal resistance change state can increase with the increase of the amount of battery lithium plating, and correspondingly, the severity of the battery lithium plating state can be aggravated with the increase of the amount of battery lithium plating.

[0124] Accordingly, the above method can also perform the following operations:

[0125] If the amount of lithium plating in the battery is greater than or equal to the second threshold and less than the third threshold, the battery lithium plating state is determined to be a first risk state; a first warning message including at least the first risk state is output to at least trigger a reduction in the charging current of the lithium battery.

[0126] Accordingly, if the amount of lithium plating in the battery is less than the second threshold or greater than or equal to the third threshold, the operation of determining the battery lithium plating state as the first risk state can be omitted.

[0127] In one implementation, the second threshold and the third threshold can be predetermined; for example, the second threshold can be 2% of the target lithium plating amount, and the third threshold can be 6% of the target lithium plating amount; for example, the target lithium plating amount can be determined or adjusted according to the physical structure of the lithium battery; for example, the target lithium plating amount can include the maximum lithium plating amount that can ensure the safe use of the lithium battery.

[0128] In one implementation, when a lithium battery is used to provide energy for a new energy vehicle, after determining that the lithium plating state of the battery is the first risk state, a first prompt message can be sent to the vehicle controller, thereby triggering the vehicle's battery management system (BMS) to control the reduction of the charging current of the lithium battery.

[0129] As can be seen from the above, the battery lithium plating state determination method provided in this application embodiment is at least related to the amount of lithium plating in the lithium battery. If the amount of lithium plating is greater than or equal to a second threshold and less than a third threshold, the battery lithium plating state is determined to be a first risk state. In this way, the correlation between the amount of lithium plating in the lithium battery and its first risk state is realized, and the amount of lithium plating in the lithium battery is also quantified in the dimension of risk state. Furthermore, by outputting a first prompt message that includes at least the first risk state, the charging current of the lithium battery is at least triggered to reduce, thereby realizing the safety protection of the lithium battery charging process. Thus, even when the lithium battery is in the first risk state, the safety of the lithium battery charging operation can still be improved.

[0130] Based on the foregoing embodiments, in the battery lithium plating state determination method provided in this application embodiment, the battery lithium plating state is at least related to the amount of lithium plating in the lithium battery.

[0131] Accordingly, the above method can also perform the following operations:

[0132] If the amount of lithium plating in the battery is greater than or equal to the third threshold, the battery lithium plating state is determined to be the second risk state.

[0133] The risk level of the second risk state is greater than that of the first risk state.

[0134] Accordingly, the above method can also perform the following operations:

[0135] The output includes at least a second warning message indicating a second risk state to trigger a reduction in the SOC of the lithium battery's charging limit.

[0136] In one implementation, the third threshold can be determined or adjusted according to the physical structure of the lithium battery.

[0137] In one implementation, the second threshold corresponding to the first risk level and the third threshold corresponding to the second risk level can be obtained by performing safety boundary tests on lithium batteries with different lithium plating amounts; wherein, the safety boundary tests may include hot box tests, accelerated rate calorimetry (ARC) tests, and nail penetration tests, etc.

[0138] Figure 4 A schematic diagram illustrating the principle of determining the lithium plating level and risk level of a battery, as provided in the embodiments of this application, is shown below. Figure 4 The horizontal axis of the two-dimensional coordinate system shown represents the lithium plating content of the battery (%), and the vertical axis represents the thermal runaway initiation temperature (°C). Figure 4 The first curve 401 and the second curve 402 shown can be obtained by fitting the thermal runaway initiation temperature corresponding to different amounts of lithium plating in the battery. Figure 4 As can be seen, the lithium plating ranges corresponding to Level I, Level II, and Level III warnings are different. Furthermore, as the warning level increases, the corresponding lithium plating increases continuously, while the corresponding thermal runaway initiation temperature decreases continuously. The basis for distinguishing between Level II and Level III warnings can be the lithium plating amount at the inflection point where the thermal runaway initiation temperature increases with the increase of lithium plating.

[0139] In one implementation, when the lithium battery is used to provide electric power for the new energy vehicle, a second prompt message can be sent to the vehicle controller, and the vehicle controller can trigger the BMS to reduce the SOC.

[0140] As can be seen from the above, in the battery lithium plating state determination method provided in this application embodiment, the battery lithium plating state is at least related to the amount of lithium plating in the lithium battery. If the amount of lithium plating is greater than or equal to a third threshold, the battery lithium plating state is determined to be a second risk state. Thus, through the above operations, the correlation between the amount of lithium plating greater than or equal to the third threshold and the second risk state is realized, thereby realizing the quantification of the amount of lithium plating in the risk state dimension. Furthermore, the risk level of the second risk state is greater than the risk level of the first risk state, and a second prompt message including at least the second risk state is output to trigger a reduction in the SOC of the lithium battery. Thus, when the amount of lithium plating in the lithium battery is large and the risk level corresponding to the second risk state is high, by reducing the SOC of the lithium battery, the battery life of the lithium battery can be extended, the safety during the use of the lithium battery can be improved, and the stability of the lithium battery voltage and the charging and discharging efficiency of the lithium battery can also be improved.

[0141] Based on the foregoing embodiments, the battery lithium plating state determination method provided in this application embodiment may further include the following steps:

[0142] Step SC1: Determine the charging cutoff voltage of the lithium battery.

[0143] In one embodiment, the charging cut-off voltage refers to the voltage value when the lithium battery reaches a fully charged state during the charging process; for example, the charging cut-off voltage can vary with changes in the physical structure of the lithium battery.

[0144] In one embodiment, the charging cutoff voltage of the lithium battery can be obtained by testing after the lithium battery reaches a fully charged state, or it can be obtained from the battery configuration parameters of the lithium battery; for example, the battery configuration parameters may include a set of parameters used to characterize the changes in current and voltage of the lithium battery during charging and discharging.

[0145] Step SC2: After the lithium battery charging process is completed, determine the resting voltage of the lithium battery.

[0146] In one implementation, resting voltage refers to the voltage of a lithium battery when it is turned off and in use; it is typically used to test the battery's capacity. In practical applications, resting voltage reflects the electrochemical state of a lithium battery when it is not in use.

[0147] In one implementation, the resting voltage may be less than the charging cut-off voltage.

[0148] Figure 5 This is a schematic diagram illustrating the changes in resting voltage and charging cutoff voltage provided in an embodiment of this application. Figure 5 The two-dimensional coordinate system shown has time on the horizontal axis and voltage (V) on the vertical axis. Figure 5As can be seen, the voltage of the lithium battery is constantly rising as the charging process progresses. When the lithium battery is fully charged, the corresponding charging cutoff voltage can be U0. After the charging process ends, as the post-charging resting process progresses, the voltage amplitude of the lithium battery gradually decreases and eventually stabilizes at the resting voltage U1. Furthermore, it can be clearly seen from the figure that the amplitude of the resting voltage is smaller than the amplitude of the charging cutoff voltage.

[0149] It should be noted that the length of the resting period after charging can be 30 seconds, 1 minute, or 5 minutes.

[0150] Step SC3: Determine the battery internal resistance based on the charging cutoff voltage and the resting voltage.

[0151] In one implementation, the battery internal resistance can be calculated as follows:

[0152] Determine the voltage difference between the charging cut-off voltage and the resting voltage, and determine the battery internal resistance based on the voltage difference and the charging end current.

[0153] As can be seen from the above, in the battery lithium plating state determination method provided in this application embodiment, the charging cut-off voltage of the lithium battery is determined, the static voltage of the lithium battery is determined after the charging process of the lithium battery is completed, and the battery internal resistance is determined based on the charging cut-off voltage and the static voltage, thereby improving the accuracy of the battery internal resistance of the lithium battery.

[0154] Figure 6 This is a flowchart illustrating the battery lithium plating state warning provided in an embodiment of this application, as shown below. Figure 6 As shown, the process may include the following steps:

[0155] S601. Determine whether the battery internal resistance deviation is greater than the first threshold.

[0156] For example, the battery can be a lithium battery.

[0157] For example, if the internal resistance deviation is greater than the first threshold, S602 to S604 can be executed; if the internal resistance deviation is less than or equal to the first threshold, S605 can be executed.

[0158] S602, Determine the amount of lithium plating in the battery.

[0159] S603. Determine the battery risk level based on the amount of lithium plating.

[0160] For example, the battery risk level may include a first level corresponding to a first risk state and a second level corresponding to a second risk state.

[0161] S604. Send an early warning signal to the BMS and take corresponding measures according to different risk levels.

[0162] For example, corresponding measures may include reducing the charging current and reducing the state of charge (SOC) as described in the foregoing embodiments.

[0163] S605, Confirmed that lithium plating has not occurred in the battery.

[0164] Through the above process, not only is dynamic, flexible and real-time monitoring of the lithium plating level of lithium batteries achieved, but also corresponding measures can be taken for different risk levels corresponding to different lithium plating levels, thereby improving the safety of lithium battery use.

[0165] Based on the foregoing embodiments, this application also provides a battery lithium plating state determination device. Figure 7 This is a schematic diagram of the battery lithium plating state determination device provided in the embodiments of this application, as shown below. Figure 7 As shown, the battery lithium plating state determination device 7 may include:

[0166] The determining module 701 is used to determine the internal resistance change state corresponding to the internal resistance of the lithium battery; and to determine the amount of lithium plating in the lithium battery based on the first correlation relationship and the internal resistance change state; wherein, the first correlation relationship includes at least the mapping relationship between the internal resistance change state and the lithium plating state.

[0167] In some embodiments, the internal resistance variation state includes internal resistance deviation; the internal resistance deviation includes the deviation between the expected internal resistance of the lithium battery and the battery internal resistance.

[0168] The determination module 701 is used to determine the lithium plating state of the lithium battery based on the first correlation relationship and the internal resistance change state if the internal resistance deviation is greater than the first threshold.

[0169] In some embodiments, the determining module 701 is used to determine the expected internal resistance of the lithium battery based on the battery cycle count and a second correlation; and to determine the internal resistance deviation based on the expected internal resistance and the battery internal resistance; wherein the second correlation includes a mapping relationship between the battery internal resistance and the battery cycle count.

[0170] In some embodiments, the determining module 701 is used to determine a set of internal resistance change states corresponding to the battery set; wherein the battery set includes multiple lithium batteries with an aging degree greater than or equal to a degree threshold.

[0171] The determination module 701 is used to determine the set of lithium plating amounts corresponding to the battery set; quantify the lithium plating amount in the set of lithium plating amounts to obtain a set of lithium plating states; and correlate the internal resistance change states in the set of internal resistance change states with the lithium plating states in the set of lithium plating states to obtain a first correlation relationship.

[0172] In some embodiments, the lithium plating state of the battery is at least associated with the amount of lithium plating in the lithium battery; the determining module 701 is configured to determine the lithium plating state as a first risk state if the amount of lithium plating is greater than or equal to a second threshold and less than a third threshold, so as to at least trigger a reduction in the charging current of the lithium battery.

[0173] In some embodiments, the lithium plating state of the battery is at least associated with the amount of lithium plating in the lithium battery; the determining module 701 is used to determine the lithium plating state as a second risk state if the amount of lithium plating is greater than or equal to a third threshold; wherein the risk level of the second risk state is greater than the risk level of the first risk state;

[0174] The determination module 701 is used to output a second warning message that includes at least a second risk state in order to trigger a reduction in the state of charge (SOC) of the lithium battery.

[0175] In some embodiments, the determining module 701 is used to determine the charging cut-off voltage of the lithium battery; determine the resting voltage of the lithium battery after the charging process of the lithium battery is completed; and determine the internal resistance of the battery based on the charging cut-off voltage and the resting voltage.

[0176] This application also provides an electronic device. Figure 8 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application, such as... Figure 8 As shown, the electronic device 8 includes a processor 801 and a memory 802; the memory 802 stores a computer program; when the computer program is executed by the processor 801, it can implement the battery lithium plating state determination method as described above.

[0177] This application also provides a computer-readable storage medium storing a computer program; when the computer program is executed by the processor of an electronic device, it can implement the battery lithium plating state determination method as described above.

[0178] This application also provides a computer program product, which includes a computer program; when the computer program is executed by the processor of an electronic device, it can implement the battery lithium plating state determination method as described above.

[0179] In some embodiments, the computer-readable storage medium may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), flash memory, magnetic surface memory, optical disc, or compact disc read-only memory (CD-ROM), etc.; or it may be a device that includes one or any combination of the above-mentioned memories.

[0180] In some embodiments, computer-executable instructions may take the form of programs, software, software modules, scripts, or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as stand-alone programs or as modules, components, subroutines, or other units suitable for use in a computing environment.

[0181] As an example, computer-executable instructions may, but do not necessarily, correspond to files in a file system. They may be stored as part of a file that holds other programs or data, for example, in one or more scripts in a Hyper Text Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple co-located files (e.g., files that store one or more modules, subroutines, or code sections).

Claims

1. A method for determining the lithium plating state of a battery, characterized in that, The method includes: Determine the internal resistance change state corresponding to the internal resistance of the lithium battery. Based on the first correlation and the internal resistance change state, the lithium plating state of the lithium battery is determined; wherein, the first correlation includes at least the corresponding mapping relationship between the internal resistance change state and the lithium plating state.

2. The method according to claim 1, characterized in that, The internal resistance change state includes at least the internal resistance deviation of the lithium battery; the internal resistance deviation includes the deviation between the expected internal resistance of the lithium battery and the battery's internal resistance; determining the lithium plating state of the lithium battery based on the first correlation and the internal resistance change state includes: If the internal resistance deviation is greater than the first threshold, the lithium plating state of the battery is determined based on the first correlation and the internal resistance change state.

3. The method according to claim 2, characterized in that, The internal resistance deviation is determined in the following way: Based on the number of battery cycles of the lithium battery and the second correlation, the expected internal resistance of the lithium battery is determined. The second correlation includes the mapping relationship between battery internal resistance and battery cycle number; The internal resistance deviation is determined based on the expected internal resistance and the battery internal resistance.

4. The method according to any one of claims 1 to 3, characterized in that, The first association was obtained in the following way: Determine the set of internal resistance change states corresponding to the battery set; wherein, the battery set includes multiple lithium batteries with an aging degree greater than or equal to a degree threshold; Determine the set of lithium plating amounts corresponding to the battery set; Quantify the amount of lithium plating in the set of battery lithium plating amounts to obtain a set of battery lithium plating states; The first association relationship is obtained by associating the internal resistance change states in the set of internal resistance change states with the battery lithium plating states in the set of battery lithium plating states.

5. The method according to any one of claims 1 to 4, characterized in that, The lithium plating state of the battery is at least related to the amount of lithium plating in the lithium battery; the method further includes: If the amount of lithium plating in the battery is greater than or equal to the second threshold and less than the third threshold, the lithium plating state of the battery is determined to be a first risk state. The output includes at least a first warning message for the first risk state, to at least trigger a reduction in the charging current of the lithium battery.

6. The method according to any one of claims 1 to 5, characterized in that, The lithium plating state of the battery is at least related to the amount of lithium plating in the lithium battery; the method further includes: If the amount of lithium plating in the battery is greater than or equal to a third threshold, the lithium plating state of the battery is determined to be a second risk state; wherein, the risk level of the second risk state is greater than the risk level of the first risk state; The output includes at least a second warning message indicating the second risk state, to trigger a reduction in the state of charge (SOC) of the lithium battery.

7. The method according to any one of claims 1 to 6, characterized in that, The method further includes: Determine the charging cutoff voltage of the lithium battery; After the charging process of the lithium battery is completed, the resting voltage of the lithium battery is determined; The internal resistance of the battery is determined based on the charging cutoff voltage and the resting voltage.

8. A battery lithium plating state determination device, characterized in that, The battery lithium plating state determination device includes: A determining module is used to determine the internal resistance change state corresponding to the internal resistance of the lithium battery; and to determine the lithium plating state of the lithium battery based on a first correlation relationship and the internal resistance change state; wherein, the first correlation relationship includes at least a mapping relationship between the internal resistance change state and the amount of lithium plating.

9. An electronic device, characterized in that, The electronic device includes a processor and a memory; the memory stores a computer program; when the computer program is executed by the processor, it can implement the battery lithium plating state determination method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The storage medium stores a computer program; when the computer program is executed by the processor of the electronic device, it can implement the battery lithium plating state determination method as described in any one of claims 1 to 7.

11. A computer program product, characterized in that, The program product includes a computer program; when the computer program is executed by the processor of an electronic device, it is able to implement the battery lithium plating state determination method as described in any one of claims 1 to 7.

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