A lithium battery lithium precipitation detection method, device, medium and vehicle

Abstract

The present application belongs to the technical field of lithium battery detection, and particularly relates to a lithium battery lithium precipitation detection method, device, medium and vehicle. Under different driving discharge voltages, the absolute value ratio of the integral change of current time and the voltage change is calculated to establish a curve function with the absolute value ratio as the Y axis and the voltage as the X axis. If the curve function decreases first, then increases and then decreases in the preset driving discharge voltage interval, it is judged that the lithium battery has lithium precipitation phenomenon in the last charging process. Through a large number of experiments and data analysis, the present application finds the different performances of lithium precipitation lithium battery and non-lithium precipitation lithium battery in the discharge process. Without the need for heating, standing or other additional means, the problem of being unable to detect lithium precipitation in the driving discharge process is solved, time, labor and cost are saved, and the present application has a very high market value.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery testing technology, and specifically relates to a lithium battery lithium plating detection method, device, medium, and vehicle. Background Technology

[0002] Lithium-ion batteries have wide applications in both consumer and power battery sectors. The growth and increasing demand from the new energy vehicle industry, in particular, has directly driven the expansion and growth of upstream battery and material companies. Consumers' concerns about new energy vehicles mainly focus on safety, range, lifespan, and cost. With the increasing reports of fires and explosions involving new energy vehicles, people are paying more and more attention to battery safety. Lithium-ion battery combustion is primarily caused by thermal runaway, and there are many causes of thermal runaway, one of which is lithium plating.

[0003] Lithium plating is a phenomenon in lithium-ion batteries where lithium ions detach from the positive electrode during charging and fail to properly embed into the negative electrode, instead gaining electrons on the negative electrode surface to form metallic lithium. Lithium plating leads to a reduction in the amount of reversible lithium in the battery system, rapid capacity decay, and a significant shortening of cycle life. Furthermore, severe lithium plating can form lithium dendrites, piercing the separator and causing a short circuit. The short circuit generates and releases heat, affecting system safety and potentially leading to catastrophic consequences such as combustion or explosion. Therefore, it is necessary to detect lithium plating in batteries during use to provide timely warnings when problems occur.

[0004] Current methods for detecting lithium plating in batteries primarily involve disassembling fully charged cells and observing the morphology of the negative electrode to determine if lithium plating has occurred. This method damages the battery, making it a destructive test. Furthermore, trace amounts of lithium plating are difficult to detect, rendering it unsuitable for practical applications and limited to research. Additionally, the three-electrode method, which involves inserting another electrode and observing the potential of the third electrode to determine lithium plating, also damages the battery's structure and is not suitable for widespread use. Finally, methods that introduce other signals such as deformation pressure for lithium plating detection suffer from high costs and limited practicality.

[0005] The optimal analysis method is to perform characteristic analysis of the voltage and current of the lithium battery during vehicle discharge to identify the changes in voltage and current after lithium plating. This avoids damaging the battery's structure and reduces the cost of lithium plating detection. However, for fresh batteries that undergo lithium plating during charging at low temperatures and then discharge at room temperature, the current-time integral-voltage curve shows no significant difference between the initial discharge curve of the lithium-plated battery and the curve of the non-lithium-plated battery. Figure 6 As shown, this is mainly because the lithium plating signal is weak and difficult to distinguish.

[0006] CN115184820A discloses a lithium plating detection method entitled "Lithium Plating Detection Method and Lithium Plating Critical Point Detection Method," which charges the battery with a preset current and then analyzes the voltage change curve to determine whether lithium plating has occurred. Its drawback is that the battery needs to be stationary during the detection process, making it impossible to detect during vehicle discharge, which is time-consuming and labor-intensive. CN112240983A discloses a lithium plating detection method entitled "Battery Lithium Plating Detection Method and Detection Device," and CN112240984A discloses a lithium plating detection method entitled "Lithium-ion Battery Lithium Plating Detection Method and Detection Device." Both patents determine whether lithium plating has occurred based on current-voltage characteristics and internal resistance-temperature characteristics, respectively. Their drawback is that both patents require heating the lithium battery, making it impossible to detect during vehicle discharge, which is also time-consuming and labor-intensive. Summary of the Invention

[0007] This invention discloses a method, device, medium, and vehicle for detecting lithium plating in lithium batteries. It solves the problem of not being able to detect lithium plating during vehicle discharge, saving time, effort, and cost, and has extremely high market value.

[0008] To address the above problems, this invention discloses a lithium battery lithium plating detection method, which involves performing the following detection steps during vehicle discharge:

[0009] The information collection steps involve collecting the current and voltage at the battery terminals during the vehicle's discharge process.

[0010] The lithium plating detection procedure involves analyzing the relationship between the discharge voltage, current flow, and voltage change under limiting conditions that can distinguish whether lithium plating has occurred, in order to determine whether lithium plating occurred during the previous charging process.

[0011] The advantage of this embodiment lies in the fact that, through extensive experiments and data analysis, it has revealed the distinct performance of lithium-plated and non-lithium-plated lithium batteries during the discharge process. Specifically, lithium-plated and non-lithium-plated lithium batteries exhibit different current throughput and voltage changes at different discharge voltages. Therefore, when determining lithium plating, heating, settling, or other additional methods are no longer required, saving time, effort, and costs, and possessing extremely high market value.

[0012] Furthermore, it also includes a lithium plating calculation step. When the lithium plating detection step determines that lithium plating has occurred in the lithium battery, the amount of lithium plating is calculated based on the SOC segment and nominal capacity corresponding to the previous charge when lithium plating occurred.

[0013] The advantage of this embodiment is that after determining that lithium plating has occurred in the lithium battery, the corresponding SOC segment at the time of lithium plating is determined, and the amount of lithium plating can be roughly obtained by estimation. The calculation is simple and the operation is convenient.

[0014] Optionally, the lithium plating detection step includes a first discharge judgment sub-step for determining whether the limiting condition is met. The sub-step determines whether the current driving discharge is the first driving discharge after a full charge. If so, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

[0015] The advantage of this embodiment is that it identifies the possible preconditions for the difference in discharge process between lithium-plated and non-lithium-plated lithium batteries, thus generating different discharge time periods. This avoids useless analysis, saves computing power, and facilitates the analysis and detection of lithium plating phenomena.

[0016] Optionally, the lithium plating detection step includes a temperature judgment sub-step for determining whether the limiting condition is met. The sub-step determines whether the temperature is within a preset temperature range when collecting current and voltage during vehicle discharge. If yes, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

[0017] The advantage of this embodiment is that it identifies the possible preconditions for the difference in discharge process between lithium-plated and non-lithium-plated lithium batteries, thus generating different temperature ranges. This avoids useless analysis, saves computing power, and facilitates the analysis and detection of lithium plating phenomena.

[0018] Specifically, the preset temperature range is above 0℃.

[0019] Optionally, the information acquisition step includes two or more adjacent sampling cycles, each sampling cycle acquiring the current and voltage at the battery terminal;

[0020] The lithium plating detection step also includes a current judgment sub-step for determining whether the limiting condition is met. It determines whether the current collected in the next sampling cycle is greater than or equal to the current collected in the previous sampling cycle. If so, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

[0021] The advantage of this embodiment is that it identifies the possible preconditions for the difference in discharge process between lithium-plated and non-lithium-plated lithium batteries, thus generating the current change pattern before the difference, avoiding useless analysis, saving computing power, and facilitating the analysis and detection of lithium plating phenomena.

[0022] Furthermore, the lithium plating detection step includes a current-voltage analysis sub-step for determining whether the limiting condition is met, which analyzes the relationship between current flow and voltage change under different vehicle discharge voltages. The specific method is as follows:

[0023] Under different vehicle discharge voltages, calculate the ratio of the absolute value of the integral change of current * time to the absolute value of the voltage change, and establish a curve function with this absolute value ratio as the Y-axis and voltage as the X-axis. If the curve function first decreases, then increases, and then decreases again within the preset vehicle discharge voltage range, it is determined that lithium plating occurred during the previous charging process of the lithium battery; otherwise, lithium plating does not occur.

[0024] The advantage of this embodiment is that by analyzing whether there are distinguishing features in the curve function with the absolute value ratio as the Y-axis and the voltage as the X-axis, it is possible to quickly determine whether lithium plating occurred in the lithium battery during the last charging process. It does not require a large number of training samples and complex regression algorithms. The comparison method is simple, the amount of computation is small, and the false positive rate is low.

[0025] Specifically, the preset driving discharge voltage range is 3.7V to 4V.

[0026] Furthermore, the lithium plating detection step includes a current-voltage analysis sub-step for determining whether the limiting condition is met, which analyzes the relationship between current flow and voltage change under different vehicle discharge voltages. The specific method is as follows:

[0027] Under different vehicle discharge voltages, the ratio of the integral change of current * time to the absolute value of the voltage change is calculated. The absolute value ratio and its corresponding vehicle discharge voltage are analyzed through a neural network model to determine whether lithium plating occurred during the previous charging process.

[0028] The method for obtaining training samples for the neural network model is as follows: experimental data of several lithium-plated and non-lithium-plated lithium batteries of the same model as the lithium battery to be tested were collected. The experimental data includes the voltage value during vehicle discharge, the ratio of the integral change of current * time to the absolute value of voltage change, and whether lithium plating has occurred.

[0029] The advantage of this embodiment is that it uses the voltage value of vehicle discharge and the integral change of current * time corresponding to the voltage value as input features, and whether lithium plating occurs as output feature. The neural network algorithm used can establish judgment models for different types of lithium batteries, and may discover unknown lithium plating features in the input and output, with high accuracy.

[0030] Optionally, the current-voltage analysis sub-step is performed in a preset DOD segment or a preset SOC segment during the discharge process.

[0031] Specifically, the preset DOD range is defined as a DOD change of ≤20% during the discharge process.

[0032] On the other hand, the present invention also discloses a lithium battery lithium plating detection device, comprising: an information acquisition module and a lithium plating detection module;

[0033] The information acquisition module collects the current and voltage at the battery terminals during the vehicle's discharge process;

[0034] The lithium plating detection module, under the constraint of being able to distinguish whether lithium plating has occurred, analyzes the relationship between the discharge voltage, current flow and voltage change during vehicle operation to determine whether lithium plating occurred during the previous charging process.

[0035] Furthermore, it also includes a lithium plating calculation module. When it is determined that lithium plating has occurred in the lithium battery, the lithium plating calculation module calculates the amount of lithium plating based on the SOC and nominal capacity corresponding to the previous charge when lithium plating occurred.

[0036] Optionally, the lithium plating detection module includes a first discharge judgment submodule. If the first discharge judgment submodule determines that this driving discharge is the first driving discharge after a full charge, then the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

[0037] Optionally, the lithium plating detection module includes a temperature judgment submodule, which is used to determine whether the temperature is within a preset temperature range when collecting current and voltage during vehicle discharge. If so, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

[0038] Optionally, the lithium plating detection module includes a current judgment submodule, which is used to determine whether the current collected in the next sampling cycle is greater than or equal to the current collected in the previous sampling cycle. If so, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

[0039] Furthermore, the lithium plating detection module includes a current-voltage analysis submodule, used to analyze the relationship between current flow and voltage change under different vehicle discharge voltages, specifically:

[0040] Under different vehicle discharge voltages, calculate the ratio of the absolute value of the integral change of current * time to the absolute value of the voltage change, and establish a curve function with this absolute value ratio as the Y-axis and voltage as the X-axis. If the curve function first decreases, then increases, and then decreases again within the preset vehicle discharge voltage range, it is determined that lithium plating occurred during the previous charging process of the lithium battery; otherwise, lithium plating does not occur.

[0041] Furthermore, the lithium plating detection module includes a current-voltage analysis submodule, used to analyze the relationship between current flow and voltage change under different vehicle discharge voltages, specifically:

[0042] Under different vehicle discharge voltages, the ratio of the integral change of current * time to the absolute value of the voltage change is calculated. The absolute value ratio and its corresponding vehicle discharge voltage are analyzed through a neural network model to determine whether lithium plating occurred during the previous charging process.

[0043] The method for obtaining training samples for the neural network model is as follows: experimental data of several lithium-plated and non-lithium-plated lithium batteries of the same model as the lithium battery to be tested were collected. The experimental data includes the voltage value during vehicle discharge, the ratio of the integral change of current * time to the absolute value of voltage change, and whether lithium plating has occurred.

[0044] On the other hand, the present invention also discloses a storage medium for storing several instructions that are suitable for processor loading to execute any of the above-described lithium battery lithium plating detection methods.

[0045] On the other hand, the present invention also discloses a vehicle including any of the above-mentioned lithium battery lithium plating detection devices and / or the above-mentioned storage medium; the vehicle also includes a lithium battery.

[0046] It should be noted that the terms "first," "second," and similar terms used in this article are merely for describing the constituent elements of the technical solution and do not constitute a limitation on the technical solution, nor should they be interpreted as an indication or implication of the importance of the corresponding elements; elements with terms such as "first," "second," or similar terms indicate that at least one of the elements is included in the corresponding technical solution. Attached Figure Description

[0047] To more clearly illustrate the technical solution of the present invention and facilitate a further understanding of its technical effects, features, and objectives, the present invention will be described in detail below with reference to the accompanying drawings. The drawings constitute an essential part of the specification and are used together with Embodiment 1 of the present invention to illustrate the technical solution of the present invention, but do not constitute a limitation on the present invention.

[0048] The same reference numerals in the attached diagrams represent the same parts, specifically:

[0049] Figure 1 This is a schematic diagram of the detection process of the present invention.

[0050] Figure 2 This is a flowchart illustrating the lithium plating detection steps.

[0051] Figure 3 This is a flowchart of Example 1.

[0052] Figure 4 This is a schematic diagram of the detection device.

[0053] Figure 5 This is a schematic diagram of the lithium plating detection module.

[0054] Figure 6 The graph shows the current-time integral versus voltage for lithium-plated and non-lithium-plated batteries.

[0055] Figure 7 The graphs show the discharge curves at different temperatures.

[0056] Figure 8 This is a graph showing the voltage-current-time integral change / voltage change for lithium-plated and non-lithium-plated batteries.

[0057] in:

[0058] 10. Vehicle discharge voltage;

[0059] 20. Current throughput;

[0060] 30. Voltage change;

[0061] 100. Information collection steps;

[0062] 200. Lithium plating detection steps;

[0063] 210. First discharge judgment sub-step;

[0064] 220. Temperature determination sub-step;

[0065] 230. Current determination sub-step;

[0066] 240. Current and voltage analysis sub-steps;

[0067] 300. Lithium plating calculation steps;

[0068] 1000. Lithium-ion battery lithium plating detection device;

[0069] 1100. Information collection module;

[0070] 1200, Lithium plating detection module;

[0071] 1210. First Discharge Judgment Submodule;

[0072] 1220. Temperature Judgment Submodule;

[0073] 1230. Current Judgment Submodule;

[0074] 1240. Current and Voltage Analysis Submodule;

[0075] 1300, Lithium plating calculation module. Detailed Implementation

[0076] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described below are merely illustrative of the technical solutions of the present invention, and not intended to limit the invention. Furthermore, the parts described in the embodiments or drawings are merely illustrative examples of relevant parts of the present invention, and not the entirety of the invention.

[0077] Example 1:

[0078] A method for detecting lithium plating in lithium batteries, such as Figure 1 , Figure 3 As shown, the following detection steps are performed during vehicle discharge:

[0079] S1, Information Collection Step 100

[0080] The system collects the current and voltage at the battery terminals during the vehicle's discharge process. Alternatively, it can acquire the current and voltage during discharge through data exchange with the ECU, or through other methods.

[0081] Furthermore, the information acquisition step 100 includes two or more adjacent sampling periods, each sampling period acquiring the current and voltage at the battery terminal. The purpose of this embodiment is to determine the magnitude of current adjacent in time, and it can also acquire current within consecutive non-equal time intervals.

[0082] S2, Lithium plating detection step 200

[0083] By analyzing the relationship between the discharge voltage 10, current flow 20, and voltage change 30, it is possible to determine whether lithium plating occurred in the lithium battery during the previous charging process. The key to this embodiment lies in the characteristic value formed by the current flow 20 and voltage change 30. The correspondence between this characteristic value and the discharge voltage can reflect whether lithium plating has occurred in the lithium battery.

[0084] Furthermore, the lithium plating detection step 200 includes a first discharge judgment sub-step 210, such as... Figure 2 As shown, determine whether this driving discharge is the first driving discharge after a full charge. If so, continue lithium plating detection; otherwise, terminate lithium plating detection.

[0085] This step is optional. The lithium plating characteristics are more obvious during the first discharge after a full charge, making it easier to detect quickly. Of course, it can also be the second, third, or other discharges after a full charge, or discharges under different charge levels. The lithium plating characteristics may appear differently at different stages of discharge.

[0086] Furthermore, the lithium plating detection step 200 includes a temperature determination sub-step 220, such as... Figure 2 As shown, when collecting current and voltage during vehicle discharge, it is determined whether the temperature is within the preset temperature range. If so, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

[0087] Specifically, the preset temperature range is above 0℃.

[0088] This step is optional. Lithium plating characteristics are more pronounced at temperatures above 0℃ and below 60℃, facilitating rapid detection. Alternatively, the temperature can be slightly below 0℃ or slightly above 60℃, as the manifestation of lithium plating characteristics may differ at different discharge temperatures. The detected signal must be within the battery's operating temperature range of 0℃ or above to eliminate interference from the initial discharge trough voltage at low temperatures, as signals from low temperatures are unreliable. Figure 7As shown. The reason is that the battery polarization is large at low temperatures, and the internal resistance is very high at the beginning of discharge, causing the voltage to drop rapidly. As discharge progresses, the battery temperature rises, and the voltage rebounds. Therefore, the voltage shows a pattern of first dropping and then rising in the initial stage of discharge, which affects the judgment of lithium plating signals.

[0089] Furthermore, the information acquisition step 100 includes two or more adjacent sampling cycles, each sampling cycle acquiring the current and voltage at the battery terminal; the lithium plating detection step 200 also includes a current judgment sub-step 230, such as... Figure 2 As shown, it is determined whether the current collected in the next sampling period is greater than or equal to the current collected in the previous sampling period. If so, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

[0090] This step is optional. When the current sampled in a later sampling period is greater than the current sampled in the previous sampling period, it is easier to distinguish whether lithium plating has occurred in the lithium battery. Of course, it is also possible to distinguish whether lithium plating has occurred in the lithium battery when the current sampled in a later sampling period is greater than the current sampled in the previous sampling period.

[0091] Furthermore, the lithium plating detection step 200 includes a current and voltage analysis sub-step 240, such as... Figure 2 As shown, the relationship between current flow 20 and voltage change 30 is analyzed under different vehicle discharge voltages 10. The specific method is as follows:

[0092] The signal in this part is processed by differentiation and derivatives. The integral change of current * time / voltage change = 30 is defined as k. The k value of lithium-plated batteries differs from that of non-lithium-plated batteries. The k value of lithium-plated batteries exhibits a trend of first decreasing, then increasing, and then decreasing again within a certain voltage range, showing a peak and a trough. The k value of non-lithium-plated batteries shows a monotonically decreasing trend within a certain range. The change in the k value can be used to determine whether lithium plating occurred during the previous charging process. Figure 8 As shown.

[0093] Specifically, the preset driving discharge voltage range is 3.7V to 4V.

[0094] In this embodiment, the curve function formed by the integral change of current * time / voltage change 30 and the vehicle discharge voltage 10 is more likely to show the difference between whether lithium plating occurs. However, it is not limited to the curve function formed by the integral change of current * time / voltage change 30 and the vehicle discharge voltage 10. It can also be the curve function formed by the integral change of voltage change 30 / current * time and the vehicle discharge voltage 10, or the curve function formed by the vehicle discharge voltage 10 and the integral change of voltage change 30 / current * time, etc.

[0095] Optionally, the current and voltage analysis sub-step 240 is performed in a preset DOD segment or a preset SOC segment during the discharge process.

[0096] Specifically, the preset DOD segment is defined as a DOD change ≤ 20% during discharge. The detected signal needs to meet the requirement that the current change during discharge at a specific DOD after the battery is fully charged conforms to a constant or increasing process. There is a strong correlation between battery polarization and current; the higher the current, the higher the polarization voltage. During discharge, terminal voltage = open-circuit voltage + polarization voltage. Under a certain SOC, the open-circuit voltage is fixed. If the discharge current decreases during the initial discharge process, the polarization voltage will decrease, and the terminal voltage will increase, affecting the judgment of the lithium plating signal.

[0097] When the battery is fully charged, it is discharged. If lithium plating occurred during the previous charge, according to the standard electrode potential table, metallic lithium will preferentially lose electrons to form lithium ions. The electrical signal of metallic lithium losing electrons in the early stage of discharge after full charge is different from the signal of lithium normally being extracted from graphite. The presence of lithium plating in the battery can be determined by calculating and processing the detected electrical signal.

[0098] This step is optional. When the change in DOD during discharge is ≤20, it is easier to distinguish whether lithium batteries have lithium plating. Of course, lithium plating may also occur in other discharge stages.

[0099] S3, Lithium plating calculation step 300

[0100] When lithium plating detection step 200 determines that lithium plating has occurred in the lithium battery, the amount of lithium plating is calculated based on the SOC level corresponding to the previous charge when lithium plating occurred and the nominal capacity. In this step, the SOC at which lithium plating was determined to have occurred during the previous charge is recorded as SOC0, and (1-SOC0)*nominal capacity is the amount of lithium plating. Because some of the deposited lithium loses electron contacts during the discharge process and cannot lose electrons to transform into lithium ions, the assessment of the amount of lithium plating has a certain degree of accuracy.

[0101] Example 2:

[0102] In Example 1, lithium plating was determined by analyzing function curve graphs. In this example, lithium plating can also be determined by mathematical analysis. The specific operation is as follows:

[0103] Let the starting time be t0, and the subsequent times be t1, t2, t3...tn-1, tn, tn+1, tn+2... with the interval between any two adjacent times being equal, defined as 30s.

[0104] At times S1 and t0, it is determined whether it is the first discharge after a full charge. If it does not meet the condition, the lithium plating signal detection and judgment will not be entered.

[0105] S2. In each sampling period, is the temperature 0℃ or above? If not, the lithium plating signal detection and judgment will not be entered.

[0106] S3. In each sampling period, the current of the next period must be greater than or equal to the current of the previous period. If this condition is not met, the lithium plating signal detection judgment will not be entered or the detection will be terminated.

[0107] S4. Determine whether the change in DOD during the discharge process is less than or equal to 20%. If it exceeds 20%, terminate the lithium plating signal detection.

[0108] S5. From time tn-1 to tn, calculate the first characteristic quantity |kn| at each time point; from tn to tn+1, calculate the first characteristic quantity |kn+1|; from tn+1 to tn+2, calculate the first characteristic quantity |kn+2|; determine the relationship between |kn+1| and |kn|. If |kn+1|-|kn|>0 before the lithium plating detection is terminated, it is determined that no lithium plating signal has appeared; if |kn+1|-|kn|<0 before the lithium plating detection is terminated, the first condition for lithium plating is met, and continue to determine |kn+2|-|kn-1|. If |kn+2|-|kn-1|>0, the second condition for lithium plating is met. If both the first and second conditions for lithium plating are met, it is determined that lithium plating occurred in the battery during the previous charging process.

[0109] Example 3:

[0110] As a replacement for the voltage analysis sub-step, the lithium plating detection step 200 includes a current-voltage analysis sub-step 240, used to analyze the relationship between the current flow 20 and the voltage change 30 under different vehicle discharge voltages 10. The specific method is as follows:

[0111] Under different vehicle discharge voltages 10, the ratio of the integral change of current * time to the absolute value of voltage change 30 is calculated. The absolute value ratio and its corresponding vehicle discharge voltage 10 are analyzed through a neural network model to determine whether lithium plating occurred during the previous charging process.

[0112] The method for obtaining training samples for the neural network model is as follows: experimental data of several lithium-plated and non-lithium-plated lithium batteries of the same model as the lithium battery to be tested were collected. The experimental data includes the voltage value during vehicle discharge, the ratio of the integral change of current * time corresponding to the voltage value to the absolute value of the voltage change 30, and the label of whether lithium plating has occurred.

[0113] In this embodiment, a neural network algorithm is used to automatically determine whether there are signs of lithium plating. The key is that the input of the neural network algorithm includes, but is not limited to, any combination of the integral change of current * time, voltage change 30, and vehicle discharge voltage 10, and the output is a judgment on whether lithium plating has occurred.

[0114] Example 4:

[0115] A lithium battery lithium plating detection device 1000, such as Figure 4 , Figure 5 As shown, it includes: an information acquisition module 1100, a lithium plating detection module 1200, and a lithium plating calculation module 1300;

[0116] Information collection module 1100:

[0117] The system collects the current and voltage at the battery terminals during vehicle discharge. In this embodiment, the information acquisition module 1100 can be a sensor group, an ECU, or other terminal capable of receiving current and voltage during vehicle discharge. The output terminal of the information acquisition module 1100 is electrically connected to the input terminal of the lithium plating detection module 1200.

[0118] Lithium plating detection module 1200:

[0119] By analyzing the relationship between the vehicle discharge voltage 10, current flow 20, and voltage change 30, it is determined whether lithium plating occurred during the previous charging process. In this embodiment, the lithium plating detection module 1200 can be an ECU, a processor installed locally in the vehicle, a remote server, or a mobile terminal.

[0120] Furthermore, the lithium plating detection module 1200 includes a first discharge determination submodule 1210. If the first discharge determination submodule 1210 determines that this driving discharge is the first driving discharge after a full charge, then the lithium plating detection continues; otherwise, the lithium plating detection is terminated. In this embodiment, the first discharge determination submodule 1210 is an optional module, which can be a combination of a sensor and a processor connected to the battery and capable of detecting battery charging and discharging, or it can be an EUC (Electronic Unstable Cell).

[0121] Furthermore, the lithium plating detection module 1200 includes a temperature judgment submodule 1220, used to determine whether the temperature is within a preset temperature range when collecting current and voltage during vehicle discharge. If so, lithium plating detection continues; otherwise, lithium plating detection is terminated. In this embodiment, the temperature judgment submodule 1220 is an optional module, which can be a combination of a temperature sensor capable of detecting battery temperature and a processor, or it can be an EUC (Electronic Underlying Cell).

[0122] Furthermore, the lithium plating detection module 1200 includes a current judgment submodule 1230, used to determine whether the current collected in the next sampling cycle is greater than or equal to the current collected in the previous sampling cycle. If so, lithium plating detection continues; otherwise, lithium plating detection is terminated. In this embodiment, the current judgment submodule 1230 is an optional module, which can be a combination of a current sensor capable of detecting the battery output current and a processor, or it can be an EUC (Electronic Unstable Cell).

[0123] Furthermore, the lithium plating detection module 1200 includes a current-voltage analysis submodule 1240, used to analyze the relationship between current flow 20 and voltage change 30 under different vehicle discharge voltages 10, specifically:

[0124] Under different vehicle discharge voltages of 10, the ratio of the absolute value of the integral change of current * time to the absolute value of the voltage change of 30 is calculated, and a curve function is established with the absolute value ratio as the Y-axis and the voltage as the X-axis. If the curve function has a peak and a trough within the preset vehicle discharge voltage range of 10, it is determined that lithium plating occurred in the previous charging process of the lithium battery; otherwise, lithium plating does not occur.

[0125] In this embodiment, the current and voltage analysis submodule 1240 receives current and voltage information sent by the information acquisition module 1100 and outputs a lithium plating judgment. The current and voltage analysis submodule 1240 can be an EUC, a remote server, or a mobile terminal.

[0126] Lithium plating calculation module 1300:

[0127] When lithium plating is detected in the lithium battery, the lithium plating calculation module 1300 calculates the amount of lithium plating based on the SOC and nominal capacity corresponding to the previous charge when lithium plating occurred.

[0128] In this embodiment, the lithium plating calculation module 1300 receives information sent by the lithium plating detection module 1200 and the information acquisition module 1100, and outputs an estimated amount of lithium plating. The lithium plating calculation module 1300 can be an EUC, or it can be a remote server or a mobile terminal.

[0129] It should be noted that the above embodiments are only for more clearly illustrating the technical solution of the present invention. Those skilled in the art will understand that the implementation of the present invention is not limited to the above content. Any obvious changes, substitutions or replacements made based on the above content do not exceed the scope of the technical solution of the present invention. Other implementations will also fall within the scope of the present invention without departing from the concept of the present invention.

Claims

1. A method for detecting lithium plating in lithium batteries, characterized in that, During vehicle discharge, the following detection steps should be performed: The information collection steps involve collecting the current and voltage at the battery terminals during the vehicle's discharge process. The lithium plating detection procedure involves analyzing the relationship between the discharge voltage, current flow, and voltage change under the limiting condition that can distinguish whether lithium plating has occurred, in order to determine whether lithium plating occurred during the previous charging process. The lithium plating detection step includes a current-voltage analysis sub-step for determining whether the limiting condition is met. This sub-step analyzes the relationship between current flow and voltage change under different vehicle discharge voltages. The specific method is as follows: Under different vehicle discharge voltages, the ratio of the absolute value of the integral change of current * time to the absolute value of the voltage change is calculated, and a curve function is established with the absolute value ratio as the Y-axis and the voltage as the X-axis. If the curve function first decreases, then increases, and then decreases again within the preset vehicle discharge voltage range, it is determined that the lithium battery exhibited lithium plating during the previous charging process; otherwise, lithium plating does not exist. The information acquisition step includes two or more adjacent sampling cycles, each sampling cycle acquiring the current and voltage at the battery terminal; The lithium plating detection step further includes a current judgment sub-step for determining whether the limiting condition is met. The sub-step determines whether the current collected in the next sampling period is greater than or equal to the current collected in the previous sampling period. If so, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

2. The lithium battery lithium plating detection method as described in claim 1, characterized in that, It also includes a lithium plating calculation step. When the lithium plating detection step determines that lithium plating has occurred in the lithium battery, the amount of lithium plating is calculated based on the SOC segment and nominal capacity corresponding to the previous charge when lithium plating occurred.

3. The lithium battery lithium plating detection method as described in claim 1, characterized in that, The lithium plating detection step includes a first discharge judgment sub-step for determining whether the limiting condition is met. It determines whether the current driving discharge is the first driving discharge after a full charge. If so, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

4. The lithium battery lithium plating detection method as described in claim 1, characterized in that, The lithium plating detection step includes a temperature judgment sub-step for determining whether the limiting condition is met. It determines whether the temperature is within a preset temperature range when collecting current and voltage during vehicle discharge. If yes, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

5. The lithium battery lithium plating detection method as described in claim 4, characterized in that, The preset temperature range is above 0°C.

6. The lithium battery lithium plating detection method as described in claim 1, characterized in that, The preset vehicle discharge voltage range is 3.7V to 4V.

7. The lithium battery lithium plating detection method as described in claim 1, characterized in that, The lithium plating detection step includes a current-voltage analysis sub-step for determining whether the limiting condition is met. This sub-step analyzes the relationship between current flow and voltage change under different vehicle discharge voltages. The specific method is as follows: Under different vehicle discharge voltages, the ratio of the integral change of current * time to the absolute value of the voltage change is calculated. The absolute value ratio and its corresponding vehicle discharge voltage are analyzed by a neural network model to determine whether lithium plating occurred during the previous charging process. The method for obtaining training samples for the neural network model is as follows: experimental data of several lithium-plated and non-lithium-plated lithium batteries of the same model as the lithium battery to be tested are collected. The experimental data includes the voltage value during vehicle discharge, the ratio of the integral change of current * time to the absolute value of the voltage change, and whether lithium plating has occurred.

8. The lithium battery lithium plating detection method as described in claim 1 or 7, characterized in that, The current and voltage analysis sub-step is performed in the preset DOD segment or preset SOC segment during the discharge process.

9. The lithium battery lithium plating detection method as described in claim 8, characterized in that, The preset DOD range is defined as a DOD change of ≤20% during the discharge process.

10. A lithium battery lithium plating detection device, characterized in that, include: Information acquisition module and lithium plating detection module; The information acquisition module collects the current and voltage at the battery terminals during the vehicle's discharge process; The lithium plating detection module, under the limiting condition of being able to distinguish whether lithium plating has occurred, analyzes the relationship characteristics between the vehicle discharge voltage, current flow and voltage change to determine whether the lithium battery has undergone lithium plating during the previous charging process. The lithium plating detection module includes a current-voltage analysis submodule, used to analyze the relationship between current flow and voltage change under different vehicle discharge voltages, specifically: Under different vehicle discharge voltages, the ratio of the absolute value of the integral change of current * time to the absolute value of the voltage change is calculated, and a curve function is established with the absolute value ratio as the Y-axis and the voltage as the X-axis. If the curve function first decreases, then increases, and then decreases again within the preset vehicle discharge voltage range, it is determined that the lithium battery exhibited lithium plating during the previous charging process; otherwise, lithium plating does not exist. The information acquisition module includes two or more adjacent sampling cycles, and each sampling cycle acquires the current and voltage at the battery terminal; The lithium plating detection module further includes a current judgment sub-step for determining whether the limiting condition is met. It determines whether the current collected in the next sampling cycle is greater than or equal to the current collected in the previous sampling cycle. If so, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

11. The lithium battery lithium plating detection device as described in claim 10, characterized in that, It also includes a lithium plating calculation module. When it is determined that lithium plating has occurred in the lithium battery, the lithium plating calculation module calculates the amount of lithium plating based on the SOC and nominal capacity corresponding to the previous charge when lithium plating occurred.

12. The lithium battery lithium plating detection device as described in claim 10, characterized in that, The lithium plating detection module includes a first discharge judgment submodule. If the first discharge judgment submodule determines that the current vehicle discharge is the first vehicle discharge after a full charge, then the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

13. The lithium battery lithium plating detection device as described in claim 10, characterized in that, The lithium plating detection module includes a temperature judgment submodule, which is used to determine whether the temperature is within a preset temperature range when collecting current and voltage during vehicle discharge. If so, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

14. The lithium battery lithium plating detection device as described in claim 10, characterized in that, The lithium plating detection module includes a current judgment submodule, which is used to determine whether the current collected in the next sampling cycle is greater than or equal to the current collected in the previous sampling cycle. If so, the lithium plating detection continues; otherwise, the lithium plating detection is terminated.

15. The lithium battery lithium plating detection device as described in claim 10, characterized in that, The lithium plating detection module includes a current-voltage analysis submodule, used to analyze the relationship between current flow and voltage change under different vehicle discharge voltages, specifically: Under different vehicle discharge voltages, the ratio of the integral change of current * time to the absolute value of the voltage change is calculated. The absolute value ratio and its corresponding vehicle discharge voltage are analyzed by a neural network model to determine whether lithium plating occurred during the previous charging process. The method for obtaining training samples for the neural network model is as follows: experimental data of several lithium-plated and non-lithium-plated lithium batteries of the same model as the lithium battery to be tested are collected. The experimental data includes the voltage value during vehicle discharge, the ratio of the integral change of current * time to the absolute value of the voltage change, and whether lithium plating has occurred.

16. A computer-readable storage medium, characterized in that, Used to store several instructions applicable to processor loading for executing the lithium battery lithium plating detection method as described in any one of claims 1 to 9.

17. A vehicle, characterized in that, The vehicle includes the lithium battery lithium plating detection device according to any one of claims 10 to 15, and / or the computer-readable storage medium according to claim 16; the vehicle also includes a lithium battery.

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