A method and device for lithium plating monitoring of a lithium battery

Abstract

The present invention provides a method for monitoring lithium plating of a lithium battery, including: collecting voltage-time data of the lithium battery of a module; extracting features from the voltage-time data to obtain voltage-time data of charge and discharge that meet a preset range; performing inflection point judgment on the voltage-time data of the charge and discharge; determining that the inflection point exists, and grading the inflection point time when the inflection point occurs; and monitoring the lithium plating amount of the lithium battery based on the level of the inflection point time. The present invention combines data feature extraction in big data with an electrochemical model, and establishes a series of log and threshold systems to monitor and give early warnings of lithium plating of the lithium battery.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management, and particularly to a method and device for detecting lithium plating of a lithium battery. Background Art

[0002] Under the background of global "carbon neutrality", the enthusiasm for seeking clean energy that can replace petroleum energy continues to rise. Solar energy, tidal energy, wind energy, water energy, etc. are clean and sustainable energy sources, but the controllability of the media for energy generation is relatively not very strong. Lithium-ion batteries are the current new generation of secondary batteries, which have a high energy density and cycle life. Currently, they are widely used in fields such as mobile communication, digital technology, electric vehicles, and energy storage. In the future, the demand for lithium-ion batteries and their materials is inestimable, and the supporting upstream and downstream industrial chains also have a huge market. Establishing a physical and chemical model for lithium batteries to obtain the simulated values of the physical and chemical state variables in the internal space and time of the battery can help to more clearly understand and monitor the real-time working state of lithium batteries, thereby better ensuring the economy, reliability, and safety of lithium batteries.

[0003] Inside a lithium battery, it is easy for lithium ions to lose or temporarily lose their activity and deposit on the surface of the electrode material, forming metallic lithium. This phenomenon is called "lithium plating". Lithium plating will cause a reduction in the available lithium ions inside the battery and an increase in heat release. Macroscopically, it is manifested as a reduction in capacity and an easy rise in temperature after operation. More dangerously, lithium ions are easily deposited into lithium dendrites, resulting in a reduction in the local electric field potential gradient, causing internal short circuits to varying degrees, and even physically piercing the separator. Therefore, it is necessary to monitor the lithium plating situation of lithium batteries, and take measures or even directly retire lithium batteries with serious lithium plating to a certain extent.

[0004] Traditional methods for detecting lithium plating in lithium-ion batteries require opening the battery where lithium plating may occur and then checking it retrospectively, without any predictability, which is not conducive to engineering implementation and has no economy. Existing non-destructive methods for monitoring lithium plating are based on the judgment of the minimum value of battery voltage over time or the judgment of the battery relaxation platform. However, in actual engineering applications, due to the existence of the sampling time interval, the data is discrete and there is a certain degree of distortion, resulting in missed judgments. In addition, existing non-destructive methods for lithium plating are based on the deduction and comparison of lithium plating using the equivalent circuit method. This method actually cannot provide any information about the internal physical parameters of lithium batteries and must rely on the comparison of prior experimental data records, which is not conducive to engineering applications and lacks predictability. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and device for monitoring lithium plating of a lithium battery to solve the problems that are not conducive to engineering applications and lack a certain degree of predictability for the battery state.

[0006] The technical solution provided by the present invention is as follows:

[0007] A method for detecting lithium plating of a lithium battery, comprising:

[0008] Collecting voltage-time data of lithium batteries in a module;

[0009] Performing feature extraction on the voltage-time data to obtain voltage-time data of charge and discharge within a preset range;

[0010] Judging inflection points for the voltage-time data of charge and discharge;

[0011] When it is determined that there is an inflection point, grading the inflection time at which the inflection point occurs;

[0012] Monitoring the lithium plating amount of the lithium battery based on the level of the inflection time.

[0013] In some embodiments, the performing feature extraction on the voltage-time data to obtain voltage-time data of charge and discharge within a preset range includes:

[0014] Judging whether the voltage-time data of charge and discharge conforms to a preset range, specifically including:

[0015] Judging whether the voltage value within the first time threshold after charging or discharging cut-off is lower than the second voltage threshold;

[0016] If so, judging whether the time during which the voltage is lower than the second voltage threshold is lower than the third time threshold;

[0017] If so, determining that the voltage-time data of charge and discharge conforms to the preset range.

[0018] In some embodiments, the determining that there is an inflection point and grading the inflection time at which the inflection point occurs includes:

[0019] Calculating the difference time between the inflection time and the cut-off moment in the voltage-time data of charge and discharge; grading the inflection time according to the difference time.

[0020] In some embodiments, the monitoring the lithium plating amount of the lithium battery based on the level of the inflection time includes:

[0021] When the inflection time is less than the fourth time threshold, creating a log file of the inflection time;

[0022] When the inflection time reaches the fifth time threshold, forcing the lithium battery to stop being used;

[0023] Wherein, the maximum value of the fourth time threshold is less than the minimum value of the fifth time threshold.

[0024] In some embodiments, the method of monitoring the amount of lithium plating of the lithium battery based on the level of the inflection point time further includes:

[0025] When the inflection point time is greater than the fourth time threshold and less than the fifth time threshold, simulate and analyze the charging data or discharging data of the lithium battery to obtain the corresponding amount of lithium plating;

[0026] Create a log file for the amount of lithium plating.

[0027] In some embodiments, when creating the log file for the amount of lithium plating, it further includes:

[0028] When it is determined that the amount of lithium plating is greater than the sixth lithium plating amount threshold and less than the seventh lithium plating amount threshold, calculate the time for the amount of lithium plating to reach the seventh lithium plating amount threshold through a time series model or an artificial intelligence model;

[0029] Based on the time for the amount of lithium plating to reach the seventh lithium plating amount threshold, give an early warning for the amount of lithium plating.

[0030] In some embodiments, it further includes:

[0031] When the amount of lithium plating reaches the seventh lithium plating amount threshold, force the lithium battery to stop being used.

[0032] A device for monitoring lithium plating of a lithium battery includes:

[0033] An acquisition module, configured to acquire voltage-time data of a lithium battery of a module;

[0034] An extraction module, configured to extract features from the voltage-time data to obtain voltage-time data of charge and discharge that meets a preset range;

[0035] A judgment module, configured to judge an inflection point of the voltage-time data of the charge and discharge;

[0036] A classification module, configured to determine the existence of the inflection point and classify the inflection point time at which the inflection point occurs;

[0037] A monitoring module, configured to monitor the amount of lithium plating of the lithium battery based on the level of the inflection point time.

[0038] In some embodiments, the extraction module is further configured to:

[0039] Judge whether the voltage-time data of the charge and discharge meets a preset range, specifically including:

[0040] Judge whether the voltage value within the first time threshold after the charge or discharge cut-off is lower than the second voltage threshold;

[0041] If so, determine whether the time when the voltage is lower than the second voltage threshold is lower than the third time threshold;

[0042] If so, determine that the voltage-time data of the charge and discharge conforms to a preset range.

[0043] In some embodiments, the grading module is configured to:

[0044] Calculate the difference time between the inflection point time and the cut-off time in the voltage-time data of the charge and discharge; and grade the inflection point time according to the difference time.

[0045] Compared with the prior art, the lithium plating monitoring method and device for a lithium battery provided by the present invention can bring the following beneficial effects:

[0046] The present invention combines the data feature extraction in big data with an electrochemical model, and establishes a series of log and threshold systems to monitor and warn of lithium plating in a lithium battery.

[0047] The present invention can understand the internal lithium plating situation without disassembling, so as to evaluate the safety state and performance state of the lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The above characteristics, technical features, advantages and implementation manners of a lithium plating monitoring method for a lithium battery will be further described below in a clear and understandable manner in conjunction with the drawings for the preferred embodiments.

[0049] Figure 1 is a flowchart of an embodiment of a lithium plating monitoring method for a lithium battery according to the present invention;

[0050] Figure 2 is a schematic diagram of an embodiment of a lithium plating monitoring device for a lithium battery according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific embodiments of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts, and other embodiments can also be obtained.

[0052] For the sake of simplicity of the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product as a whole. Additionally, for the sake of simplicity and ease of understanding of the drawings, in some figures, only one of the components with the same structure or function is schematically shown, or only one of them is labeled. In this document, "one" not only means "only this one", but also can mean "more than one" situation.

[0053] In one embodiment, as Figure 1 shown, the present invention provides a method for monitoring lithium plating of a lithium battery, including:

[0054] S101 Collect the voltage-time data of the lithium batteries in a module.

[0055] Specifically, the voltage is collected by a voltage sensor in the battery management system.

[0056] It should be noted that a module generally has levels such as single cell, box, cluster, and stack. Each level has a certain electrical topology structure. Currently, for each level, the battery management system will sense the voltage. In fact, the present invention is limited by the physical installation conditions of the sensor.

[0057] Collect the voltage-time data of all the battery voltages in a certain module level of the application scenario. Here, the module level is limited by the level of the acquisition sensor. Preferably, collect up to the cluster level, that is, use the cluster-level voltage-time data. Otherwise, use the battery voltage-time data of the lowest module level. For those with special requirements, the single-cell level battery voltage-time data can be collected.

[0058] S102 Extract features from the voltage-time data to obtain the voltage-time data of charge and discharge within a preset range.

[0059] Specifically, judging whether the charge and discharge data is qualified is used as the basis for judging the lithium plating amount.

[0060] S103 Perform an inflection point judgment on the voltage-time data of the charge and discharge.

[0061] Specifically, for the extracted voltage-time data, judge whether there is an inflection point and the time from the appearance of the inflection point to the cut-off moment.

[0062] Among them, the definition of an inflection point on a continuous function is a point where the second derivative is 0 and the second derivative changes sign on the left and right. Intuitively, in the present invention, it is a point on the curve where the graph changes from convex upward to convex downward or vice versa before and after this point. But for discrete data, it is defined as a point where the second-order difference quotient changes sign before and after this point.

[0063] In a specific embodiment, within the time window of 3600 s, the absolute value of the current does not exceed 3 A, and if there is a current less than 3 A, the total duration thereof does not exceed 300 s.

[0064] Definition of inflection point: An inflection point, also known as a point of inflection, refers in mathematics to a point that changes the upward or downward direction of a curve. Intuitively, an inflection point is a point where the tangent line crosses the curve, that is, the demarcation point between the concave arc and the convex arc of a continuous curve.

[0065] The implementation of the present invention is to perform a difference calculation on voltage-time data, that is, to calculate the previous one minus the next one of a voltage time series to obtain a new time series, and pay attention to the time point at which the new time series significantly changes sign, which is the inflection point.

[0066] S104 Determine that the inflection point exists, and classify the inflection point time at which the inflection point occurs.

[0067] Specifically, classify the time from the occurrence of the data inflection point to the cut-off moment.

[0068] S105 Monitor the amount of lithium plating of the lithium battery based on the level of the inflection point time.

[0069] The present invention provides a method for monitoring lithium plating of a lithium battery based on battery data feature extraction and an electrochemical model. First, collect all battery voltage-time data at a certain module level of the application scenario, extract the charging and discharging cut-off times in this data set through data features, and then perform an inflection point detection on the voltage-time data within the relaxation time after cut-off to check whether there is an inflection point and the time from the inflection point to the cut-off moment. For data with a time greater than different thresholds, perform strategy processing. For battery voltage data exceeding the strictest threshold, substitute it into the electrochemical model for simulation, and deduce and simulate the lithium plating situation of the lithium battery according to the battery enlightenment situation, and monitor and give early warnings by establishing a log.

[0070] In this embodiment, through the charging and discharging cut-off judgment and inflection point time extraction of battery data, the deduction and simulation of the electrochemical model in lithium plating, as well as the threshold judgment and grading system, ensure effectiveness and economy.

[0071] In one embodiment, the feature extraction of the voltage-time data to obtain voltage-time data of charging and discharging within a preset range includes:

[0072] Judging whether the voltage-time data of the charging and discharging conforms to a preset range, specifically including:

[0073] Judging whether the voltage value within the first time threshold after charging or discharging cut-off is lower than the second voltage threshold;

[0074] If so, determine whether the time when the voltage is lower than the second voltage threshold is lower than the third time threshold;

[0075] If so, determine that the voltage-time data of the charge and discharge conforms to a preset range.

[0076] Specifically, the judgment of the first time threshold, i.e., threshold 1, the second voltage threshold, i.e., threshold 2, and the third time threshold, i.e., threshold 3, is to screen and clean qualified charge and discharge data for data processing. The required charge and discharge data are the data that have been sufficiently static after charging or discharging is completed. The sufficient standard here is that within the time period of threshold 1, a current exceeding threshold 2 is not allowed to exist, and the total time during which a current lower than threshold 2 exists within the time period of threshold 1 is less than threshold 3.

[0077] In a specific embodiment, within the time window of 3600s, the absolute value of the current does not exceed 3A, and if there is a current less than 3A, its total duration does not exceed 300s.

[0078] In one embodiment, the determining the existence of the inflection point and grading the inflection point time of the occurrence of the inflection point includes:

[0079] Calculate the difference time between the inflection point time and the cut-off moment in the voltage-time data of the charge and discharge; grade the inflection point time according to the difference time.

[0080] In one embodiment, the monitoring of the lithium deposition amount of the lithium battery based on the level of the inflection point time includes:

[0081] When the inflection point time is less than the fourth time threshold, establish a log file of the inflection point time;

[0082] When the inflection point time reaches the fifth time threshold, force the lithium battery to stop being used;

[0083] Wherein, the maximum value of the fourth time threshold is less than the minimum value of the fifth time threshold.

[0084] Specifically, the fourth time threshold, i.e., threshold 4, and the fifth time threshold, i.e., threshold 5, are the thresholds for a three-level early warning response to the occurrence time of the inflection point. When it is lower than threshold 4, the lithium deposition is not obvious, but a log is made. When it is between threshold 4 and threshold 5, the specific lithium deposition situation needs to be calculated and simulated, and a big data model or an electrochemical model simulation can be used. When it is above threshold 5, it is forced to be retired.

[0085] In one embodiment, the monitoring of the lithium deposition amount of the lithium battery based on the level of the inflection point time further includes:

[0086] When the inflection point time is greater than the fourth time threshold and less than the fifth time threshold, perform simulation on the charging data or discharging data of the lithium battery to obtain the corresponding amount of lithium deposition.

[0087] Create a log file for the amount of lithium deposition.

[0088] In one embodiment, when creating the log file for the amount of lithium deposition, it further includes:

[0089] When it is determined that the amount of lithium deposition is greater than the sixth lithium deposition threshold and less than the seventh lithium deposition threshold, calculate the time for the amount of lithium deposition to reach the seventh lithium deposition threshold through a time series model or an artificial intelligence model.

[0090] Based on the time for the amount of lithium deposition to reach the seventh lithium deposition threshold, give an early warning for the amount of lithium deposition.

[0091] When the amount of lithium deposition reaches the seventh lithium deposition threshold, force the lithium battery to stop being used.

[0092] Specifically, for the simulation of the amount of lithium deposition between threshold 4 and threshold 5, a three - level early warning response is carried out. The corresponding two thresholds are the sixth lithium deposition threshold, i.e., threshold 6, and the seventh lithium deposition threshold, i.e., threshold 7. For the situation between threshold 6 and threshold 7, calculate and estimate the situation of reaching threshold 7. Above threshold 7, force retirement.

[0093] Exemplarily, after monitoring the voltage data for 3000s, look at the moment when the inflection point appears. For example, if it is 1400s here, it is a three - level response, corresponding to two threshold judgments, namely threshold 4 and threshold 5.

[0094] For example: Judge the relationship between 1400s and 1000s, 1500s, and then perform operations according to the relationship. If 1400s is greater than 1000s and less than 1500s, then the lithium battery has a certain amount of lithium deposition, but it is not the most serious level. At this time, identify or simulate the amount of lithium deposition during this discharge for this amount of lithium deposition through artificial intelligence. After obtaining it, make a judgment. Here is another three - level response, corresponding to another two threshold judgments, namely threshold 6 and threshold 7.

[0095] In one embodiment, the present invention provides a method for monitoring lithium deposition of a lithium battery based on battery data extraction and an electrochemical model.

[0096] First, it collects all the battery voltage - time data at the module level of the application scenario, extracts the charging and discharging cut - off times in this dataset through data features, and then performs inflection point detection on the voltage - time data within the relaxation time after cut - off to check whether there is an inflection point and the time of the inflection point from the cut - off moment, and classifies the data with time greater than different thresholds.

[0097] For some levels, such as the single cell level, the data: the electrochemical parameters required for electrochemical model simulation and the environment and working conditions of the real battery that the virtual battery twins are substituted into the electrochemical model for simulation. The lithium plating situation of the lithium battery is deduced and simulated according to the battery enlightenment situation, involving the physical meaning of the model, numerical simulation, and algorithm optimization. For all levels, monitoring and early warning are carried out by establishing logs.

[0098] A lithium battery lithium plating monitoring method based on battery data feature extraction and electrochemical model according to the present invention includes the following steps:

[0099] Step S1: Battery voltage-time data acquisition. The voltage is acquired by a voltage sensor in the battery management system. Generally, there are levels such as single cell - box - cluster - stack. Each level has a certain electrical topology structure. Currently, the battery management system corresponding to each level has voltage sensing. In fact, the present invention is limited by the physical installation conditions of the sensor.

[0100] Collect all the battery voltage-time data of a certain module level in the application scenario. The module level here is limited by the level of the acquisition sensor. Preferably, the cluster level voltage-time data can be adopted, that is, the cluster level voltage-time data is used, otherwise the battery voltage-time data of the lowest module level is used. For those with special requirements, the single cell level battery voltage-time data can be collected.

[0101] Step S2: Battery voltage-time data extraction:

[0102] Extract the battery voltage-time data. First, extract the qualified charge and discharge data. The basic requirement is that the total duration of charge or discharge with a current lower than a certain threshold 2 within a certain threshold 1 time after charge or discharge cut-off is lower than a certain threshold 3. This extraction can be based on logical judgment of the collected data or through underlying feature extraction methods of artificial intelligence such as convolution.

[0103] Exemplarily, if a battery discharges to cut-off, then take the voltage-time data of this battery within 3000s after the discharge cut-off, obtain the number of seconds corresponding to the voltage with a voltage value lower than 2.8V in the voltage data of these 3000s, and further judge whether this number of seconds is lower than 1500s.

[0104] Among them, 3000s is threshold 1, 2.8V is threshold 2, and 1500s is threshold 3. This is mainly to judge whether the charge and discharge data is qualified as the judgment basis for lithium plating monitoring.

[0105] Step S3, inflection point judgment: First, judge the inflection point. When it is greater than threshold 4 and less than threshold 5, judge the amount of lithium deposition of the child node. If the amount of lithium deposition is large, it is forced to retire. If the amount of lithium deposition is not very large, judge how long it will take for the amount of lithium deposition to become large, and predict and give an early warning about how long it will take to become large.

[0106] After that, for the extracted voltage-time data, judge whether there is an inflection point and the time from the inflection point to the cut-off moment. The definition of an inflection point on a continuous function is a point where the second derivative is 0 and the second derivative changes sign on both sides. Intuitively, it is the graph of the curve, a point where the convexity changes from upward to downward or vice versa before and after this point. But for discrete data, it is defined as a point where the second-order difference quotient changes sign before and after this point.

[0107] Step S4, threshold judgment and classification:

[0108] Classify according to the time from the data inflection point to the cut-off moment.

[0109] For those with an inflection point and the inflection point time less than threshold 4, establish a log of the inflection point time.

[0110] For those with the inflection point time reaching threshold 5, force retirement.

[0111] For those with the inflection point time greater than threshold 4 and less than threshold 5, simulate and analyze the charging or discharging data of the battery each time. Here, the amount of lithium deposition during this charging or discharging is obtained through parameter identification of artificial intelligence and electrochemical simulation, and a log of the amount of lithium deposition is established. At the same time, note that the current working condition and temperature need to be obtained during the simulation.

[0112] For those with the amount of lithium deposition judged to be greater than threshold 6 and less than threshold 7, calculate and predict the time when it reaches threshold 7 through a time series model or an artificial intelligence model.

[0113] Predict and give an early warning about the time when it reaches threshold 7. If the amount of lithium deposition has reached threshold 7, force retirement.

[0114] In one embodiment, the present invention provides a lithium deposition monitoring device for a lithium battery, as Figure 2 shown, including:

[0115] A collection module 101, configured to collect voltage-time data of lithium batteries in a module.

[0116] An extraction module 102, configured to extract features from the voltage-time data to obtain voltage-time data of charge and discharge within a preset range.

[0117] A judgment module 103, configured to judge inflection points for the voltage-time data of charge and discharge.

[0118] A grading module 104 is used to determine the existence of the inflection point and grade the inflection point time when the inflection point occurs.

[0119] A monitoring module 105 is used to monitor the amount of lithium plating of the lithium battery based on the level of the inflection point time.

[0120] In one embodiment, the extraction module is further used for:

[0121] Judge whether the voltage-time data of the charge and discharge conforms to a preset range, specifically including:

[0122] Judge whether the voltage value within the first time threshold after the charge or discharge cut-off is lower than the second voltage threshold;

[0123] If so, judge whether the time when it is lower than the second voltage threshold is lower than the third time threshold;

[0124] If so, determine that the voltage-time data of the charge and discharge conforms to the preset range.

[0125] In one embodiment, the grading module is used for:

[0126] Calculate the difference time between the inflection point time and the cut-off moment in the voltage-time data of the charge and discharge; grade the inflection point time according to the difference time.

[0127] The present invention adopts a method combining data feature extraction in big data and an electrochemical model, and establishes a series of log and threshold systems to monitor and warn of lithium plating of lithium batteries.

[0128] It should be noted that the above embodiments can be freely combined as needed. The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for monitoring lithium plating of a lithium battery, characterized in that, Including: Collecting voltage-time data of the lithium battery of a module; Performing feature extraction on the voltage-time data to obtain charge-discharge voltage-time data that meets a preset range; wherein, judging whether the charge-discharge voltage-time data meets the preset range specifically includes: judging whether the voltage value within the first time threshold after charge or discharge cut-off is lower than the second voltage threshold; if so, judging whether the time during which the voltage is lower than the second voltage threshold is lower than the third time threshold; if so, determining that the charge-discharge voltage-time data meets the preset range; Performing inflection point judgment on the charge-discharge voltage-time data; Determining that there is such an inflection point and grading the inflection point time at which the inflection point occurs; the inflection point is a point on a continuous function where the second derivative is 0 and the second derivatives on the left and right change signs; Monitoring the amount of lithium plating of the lithium battery based on the level of the inflection point time, specifically including: When the inflection point time is less than the fourth time threshold, creating a log file of the inflection point time; When the inflection point time reaches the fifth time threshold, forcing the lithium battery to stop being used; Wherein, the maximum value of the fourth time threshold is less than the minimum value of the fifth time threshold; When the inflection point time is greater than the fourth time threshold and less than the fifth time threshold, performing simulation on the charge data or discharge data of the lithium battery to obtain the corresponding amount of lithium plating; Creating a log file for the amount of lithium plating.

2. The lithium plating monitoring method for a lithium battery according to claim 1, wherein The determining that there is such an inflection point and grading the inflection point time at which the inflection point occurs includes: Calculating the difference time between the inflection point time and the cut-off moment in the charge-discharge voltage-time data; grading the inflection point time according to the difference time.

3. A method for monitoring lithium plating of a lithium battery according to any one of claims 1 to 2, characterized in that, In creating the log file for the amount of lithium plating, it further includes: When it is determined that the amount of lithium plating is greater than the sixth lithium plating amount threshold and less than the seventh lithium plating amount threshold, calculating the time for the amount of lithium plating to reach the seventh lithium plating amount threshold through a time series model or an artificial intelligence model; Issuing a warning for the amount of lithium plating based on the time for the amount of lithium plating to reach the seventh lithium plating amount threshold.

4. The lithium plating monitoring method for a lithium battery according to claim 3, characterized in that, It also includes: When the amount of lithium plating reaches the seventh lithium plating amount threshold, forcing the lithium battery to stop being used.

5. A lithium plating monitoring device for a lithium battery, characterized in that, Including: A collection module for collecting voltage-time data of the lithium battery of a module; An extraction module for performing feature extraction on the voltage-time data to obtain charge-discharge voltage-time data that meets a preset range; The extraction module is further used for: judging whether the charge-discharge voltage-time data meets the preset range, specifically including: judging whether the voltage value within the first time threshold after charge or discharge cut-off is lower than the second voltage threshold; if so, judging whether the time during which the voltage is lower than the second voltage threshold is lower than the third time threshold; if so, determining that the charge-discharge voltage-time data meets the preset range; A judgment module for performing inflection point judgment on the charge-discharge voltage-time data; A grading module for determining that there is such an inflection point and grading the inflection point time at which the inflection point occurs; the inflection point is a point on a continuous function where the second derivative is 0 and the second derivatives on the left and right change signs; A monitoring module, configured to monitor the amount of lithium plating of the lithium battery based on the level of the inflection point time, specifically including: when the inflection point time is less than a fourth time threshold, establishing a log file of the inflection point time; when the inflection point time reaches a fifth time threshold, forcing the lithium battery to stop being used; wherein, the maximum value of the fourth time threshold is less than the minimum value of the fifth time threshold; when the inflection point time is greater than the fourth time threshold and less than the fifth time threshold, performing a simulation on the charging data or discharging data of the lithium battery to obtain a corresponding amount of lithium plating; and establishing a log file for the amount of lithium plating.

6. The lithium plating monitoring device for a lithium battery according to claim 5, characterized in that, The grading module is configured to: calculate a difference time between the inflection point time and the cut-off moment in the voltage-time data of the charge and discharge; and grade the inflection point time according to the difference time.

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