Method and device for detecting lithium precipitation amount of lithium battery, computer equipment and storage medium
By combining the charging curve and actual disassembly method to construct the lithium-extraction model, the problem of quantitative detection and distinction between reversible lithium and irreversible lithium in the existing technology is solved, and the accurate detection and distinction of lithium-extraction amount of lithium batteries is achieved, which is of great engineering significance.
Patent Information
- Application Number
- CN202311755130.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-19
- Publication Date
- 2025-06-20
AI Technical Summary
The existing lithium-ion detection methods cannot conduct quantitative testing, and cannot distinguish between reversible lithium and irreversible lithium, which has major disadvantages.
By combining the charging curve and actual disassembly, the lithium-ion analysis model is constructed, and the first and second expressions reflect the mapping relationship between the target characteristics of the lithium battery and the lithium-ion analysis amount are obtained, thereby realizing quantitative detection of the reversible lithium-ion analysis amount and the irreversible lithium-ion analysis amount.
Quantitative detection of lithium-ion analysis amount of lithium-ion batteries is realized, distinguishing between reversible lithium-ion analysis and irreversible lithium-ion analysis, retaining the integrity of the battery, and has important engineering significance.
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Figure CN120178055A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of lithium metal deposition detection in lithium batteries, and specifically provides a method, device, computer device and storage medium for detecting the amount of lithium metal deposition in lithium batteries. Background Art
[0002] Under charging conditions such as low-temperature charging, high-rate charging or overcharging, lithium ions inside the lithium battery are likely to precipitate on the negative electrode surface of the lithium battery in the form of metallic lithium, that is, the phenomenon of lithium metal deposition occurs. The precipitated metallic lithium may form lithium dendrites, resulting in the attenuation of the lithium battery capacity, or piercing the electrolyte membrane to cause the battery to short-circuit. Therefore, it is of great significance to detect the amount of lithium metal deposition in lithium batteries.
[0003] Currently, in related technologies, the methods for lithium metal deposition detection are generally divided into two types: destructive detection and non-destructive detection. Destructive detection means disassembling the battery to detect the amount of lithium metal deposition, which will directly damage the battery. Non-destructive detection means collecting and analyzing online data during the charging and discharging process of the battery. However, on the one hand, this method is mainly qualitative detection and cannot directly obtain the numerical value of the amount of lithium metal deposition. On the other hand, it cannot distinguish between reversible and irreversible lithium metal deposition, and there are significant drawbacks.
[0004] Correspondingly, there is a need in the art for a new lithium metal deposition detection solution to solve the above problems. Summary of the Invention
[0005] The present application aims to solve the above technical problems, that is, to solve the problem that the existing lithium metal deposition detection methods cannot quantitatively detect the amount of lithium metal deposition in lithium batteries.
[0006] In a first aspect, the present application provides a method for detecting the amount of lithium metal deposition in a lithium battery, which includes:
[0007] During the application process of the lithium battery, detecting the current value of the target feature;
[0008] Inputting the current value into a lithium metal deposition model to determine the amount of lithium metal deposition in the lithium battery;
[0009] Wherein, the lithium metal deposition model reflects the mapping relationship between the target feature of the lithium battery and the amount of lithium metal deposition, and the target feature includes a first feature representing the amount of irreversible lithium metal deposition and / or a second feature representing the amount of reversible lithium metal deposition.
[0010] In a technical solution of the above detection method, the first feature includes a first sub-feature representing the loss of negative electrode active material of the lithium battery and a second sub-feature representing the loss of active lithium of the lithium battery;
[0011] The first sub-feature and the second sub-feature are obtained from the charging curve of the lithium battery.
[0012] In one technical solution of the above detection method, the amount of lithium deposition is the reversible amount of lithium deposition, and the feature is the second feature representing the reversible amount of lithium deposition.
[0013] In one technical solution of the above detection method, the amount of lithium deposition includes the reversible amount of lithium deposition and the irreversible amount of lithium deposition, and the features include the first feature representing the irreversible amount of lithium deposition and the second feature representing the reversible amount of lithium deposition.
[0014] In one technical solution of the above detection method, the lithium deposition model includes a first expression constructed based on the first sub-feature, the second sub-feature, and the irreversible amount of lithium deposition.
[0015] In one technical solution of the above detection method, the first expression is determined by performing cyclic charge and discharge and actual disassembly on two groups of test batteries.
[0016] In one technical solution of the above detection method, the second feature represents the time corresponding to the minimum value based on the charging curve during the static process of the lithium battery.
[0017] In one technical solution of the above detection method, the lithium deposition model includes a second expression constructed based on the second feature and the reversible amount of lithium deposition.
[0018] In one technical solution of the above detection method, the second expression is determined by performing cyclic charge and discharge and actual disassembly on two groups of test batteries.
[0019] In a second aspect, the present application provides a detection device for the amount of lithium deposition in a lithium battery, which includes:
[0020] A detection module, which is used to detect the current value of the target feature during the application process of the lithium battery;
[0021] A lithium deposition amount determination module, which is used to input the current value into the lithium deposition model to determine the amount of lithium deposition of the lithium battery.
[0022] In a third aspect, the present application provides a computer device, including a processor and a storage device, the storage device is suitable for storing multiple program codes, and the program codes are suitable for being loaded and run by the processor to execute the detection method described in any one of the first aspect.
[0023] In a fourth aspect, the present application provides a computer-readable storage medium, in which multiple program codes are stored, and the program codes are suitable for being loaded and run by a processor to execute the detection method described in any one of the first aspect.
[0024] As described above, in the case of adopting the above technical solution, the present application combines two methods of lossy detection and non-destructive detection, that is, combines the charging curve and the actual disassembly method to construct a lithium plating model. Based on the charging curve, the first sub-feature, the second sub-feature, and the second feature reflecting irreversible lithium plating of the lithium battery are obtained. Then, by actually disassembling the battery, the irreversible lithium plating amount and the reversible lithium plating amount are obtained. Thus, experiments are carried out respectively under various working conditions to establish the mapping relationship between the first sub-feature, the second sub-feature and the irreversible lithium plating amount, and the mapping relationship between the second feature and the reversible lithium plating amount, and a lithium plating model is obtained. Therefore, during subsequent actual vehicle operation or battery production and R & D process, the current values of the above features can be obtained through the charging curve of the battery to be tested, and the current values are directly input into the lithium plating model to obtain the reversible lithium plating amount and the irreversible lithium plating amount of the battery to be tested.
[0025] Through the construction of the lithium plating model in the early stage, when detecting the lithium plating amount of the battery in the later stage, on the one hand, there is no need to disassemble the battery, which retains the integrity of the battery. On the other hand, through the lithium plating model, the reversible lithium plating amount and the irreversible lithium plating amount of the battery can be quantitatively detected at the same time to reflect the actual problems of the battery, which has important reference significance for adjusting the battery management strategy and improving the battery structure. Therefore, by establishing a lithium plating model to distinguish the reversible lithium plating amount and the irreversible lithium plating amount, and calculate parameters such as the ratio and total amount of the two, it is not only beneficial to the real-time detection during actual vehicle operation, but also can obtain the required lithium plating parameters in real time during the design and R & D link of the battery to reflect the problems of the battery, and then adjust the corresponding structure of the battery to obtain a battery product with better performance. Therefore, the method of the present application has important engineering significance for both actual vehicle operation and design and R & D. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Referring to the accompanying drawings, the disclosure of the present application will become more understandable. It is easy for those skilled in the art to understand that: these drawings are only for illustrative purposes and are not intended to limit the protection scope of the present application. In addition, similar numbers in the drawings are used to represent similar components, where:
[0027] Figure 1 is a schematic diagram of the charging curve and the dV / dQ curve during the battery charging process.
[0028] Figure 2 is a main step flow chart of the method for detecting the lithium plating amount of a lithium battery according to an embodiment of the present application;
[0029] Figure 3 is a detailed step flow chart of the construction of the lithium plating model according to an embodiment of the present application.
[0030] Figure 4 is a detailed step flow chart of the method for detecting the lithium plating amount of a lithium battery according to an embodiment of the present application. Detailed implementation manners
[0031] The preferred implementation manners of the present application will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these implementation manners are only used to explain the technical principle of the present application and are not used to limit the protection scope of the present application. Those skilled in the art can make adjustments according to needs to adapt to specific application scenarios.
[0032] In the description of the present application, "module" and "processor" may include hardware, software or a combination of both. A module may include a hardware circuit, various suitable sensors, communication ports, memories, and may also include a software part, such as program code, or may be a combination of software and hardware. The processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor or any other suitable processor. The processor has data and / or signal processing functions. The processor can be implemented in software, in hardware or in a combination of both. The non-transitory computer-readable storage medium includes any suitable medium that can store program code, such as magnetic disks, hard disks, optical discs, flash memories, read-only memories, random access memories, and so on. The term "A and / or B" represents all possible combinations of A and B, such as only A, only B, or A and B. The term "at least one of A or B" or "at least one of A and B" has a meaning similar to "A and / or B" and may include only A, only B, or A and B. The singular terms "a" and "this" may also include the plural form.
[0033] The lithium plating of a lithium battery is divided into reversible lithium plating and irreversible lithium plating. Reversible lithium plating refers to the lithium metal deposited on the negative electrode surface during the charging process. This part of the lithium metal can be re-embedded into the negative electrode during the small current charging section or the static section after charging is completed. In addition, it can also be stripped from the negative electrode surface during the discharging section and return to the charge-discharge cycle again. The amount of lithium plating in this part will not cause the attenuation of the battery capacity. Irreversible lithium plating refers to the fact that the precipitated lithium metal loses electrical connection with the negative electrode and thus cannot return to the charge-discharge cycle. Therefore, irreversible lithium plating will cause the loss of active lithium in the battery, resulting in a reduction in the battery capacity. Moreover, irreversible lithium plating may also form lithium dendrites, piercing the electrolyte membrane, causing a short circuit in the battery structure, and further possibly triggering the risk of thermal runaway.
[0034] Therefore, in the design and research and development or actual application of lithium batteries, it is often necessary to detect the amount of lithium plating in lithium batteries. The detection methods of the amount of lithium plating in lithium batteries usually include two methods: destructive testing and non-destructive testing. Destructive testing means disassembling the battery and then detecting the amount of lithium plating in the battery by means of electron microscope scanning, X-ray diffraction, oxide titration, etc. This method cannot distinguish the reversible lithium plating amount from the irreversible lithium plating amount. More importantly, it will directly cause the battery to be damaged and has irreversibility.
[0035] The non-destructive testing methods mainly include the following: First, cycling charge and discharge the battery to observe the change of Coulomb efficiency. This method takes a long time, consumes a large amount of energy, and requires a high precision for Coulomb efficiency. The sampling conditions and working conditions of actual vehicles can hardly meet these requirements, and this method can only detect the irreversible lithium deposition amount. Second, based on the voltage signal during the static / discharge section after lithium deposition during battery charging, detect whether the battery has lithium deposition. This type of detection method requires a large amount of lithium deposition during a single charge and is difficult to detect cumulative irreversible lithium deposition. Third, use the EIS signal to calculate the ohmic impedance and SEI film impedance of the battery, and detect lithium deposition through its abnormal changes. The main difficulty of this method is that the online acquisition of the EIS signal requires additional hardware support, which is difficult to achieve based on the existing current and voltage signals, and this method cannot distinguish between the reversible lithium deposition amount and the irreversible lithium deposition amount.
[0036] It can be seen that on the one hand, the above detection methods are relatively difficult to implement technically, and on the other hand, they can only achieve qualitative detection or semi-quantitative detection, cannot directly obtain the reversible lithium deposition amount and irreversible lithium deposition amount of the battery, and the detection accuracy is low. Therefore, the above methods all have great drawbacks.
[0037] Refer to Figure 2 , a method for detecting the lithium deposition amount of a lithium battery disclosed in this application, which includes the following steps:
[0038] Step 1: During the application process of the lithium battery, detect the current value of the target feature.
[0039] Among them, the target feature includes a first feature representing the irreversible lithium deposition amount and / or a second feature representing the reversible lithium deposition amount.
[0040] Step 2: Input the current value into the lithium deposition model to determine the lithium deposition amount of the lithium battery.
[0041] Among them, the lithium deposition model reflects the mapping relationship between the target feature of the lithium battery and the lithium deposition amount. The lithium deposition model is constructed through the charging curve and the actual disassembly of the lithium battery. The charging curve refers to the voltage-capacity change curve of the lithium battery obtained during the charging process of the lithium battery. The actual disassembly refers to the method of disassembling and detecting the battery to obtain the lithium deposition amount.
[0042] In some implementation manners of this application, in step 2, the lithium deposition amount can be only the irreversible lithium deposition amount. At this time, the target feature is the first feature representing the irreversible lithium deposition amount. The lithium deposition amount can also be only the reversible lithium deposition amount. At this time, the feature is the second feature representing the reversible lithium deposition amount. Of course, the lithium deposition amount can also include both the reversible lithium deposition amount and the irreversible lithium deposition amount. At this time, the features include the first feature representing the irreversible lithium deposition amount and the second feature representing the reversible lithium deposition amount.
[0043] Refer to Figure 1 , specifically,Figure 1 (a) is the charging curve obtained by charging the battery based on the slow charging strategy. Among them, curve A1 is the voltage-capacity curve of the positive electrode of the battery, curve B1 is the voltage-capacity curve of the negative electrode of the battery, and curve C1 is the voltage-capacity curve of the full battery. Figure 1 (b) is based on Figure 1 (a)'s dV / dQ curve. Curve A2 is the dV / dQ curve of the positive electrode of the battery, curve B2 is the dV / dQ curve of the negative electrode of the battery, and curve C2 is the dV / dQ curve of the full battery.
[0044] AN1, AN2, and AN3 are the characteristic peaks of the positive electrode, and CA1 and CA2 are the characteristic peaks of the negative electrode. Based on the above characteristic peaks, Figure 1 In (b), the physical meaning represented by L1 is the loss of the positive electrode active material, the physical meaning represented by L2 is the loss of the negative electrode active material, and the physical meaning represented by L3 is the loss of active lithium. When irreversible lithium plating occurs, the values of L2 and L3 will decrease accordingly. Therefore, the dV / dQ curve of the lithium battery reflects the attenuation of the battery capacity, which is a well-known technology in the art and will not be elaborated much in this application.
[0045] The lithium plating amount detection method of this application first constructs a lithium plating model through the charging curve and actual disassembly. Then, during the actual operation of the subsequent lithium battery, by detecting the target characteristics of the lithium battery reflected in the lithium plating model, and then inputting the current value of the target characteristics into the lithium plating model, the actual lithium plating amount of the lithium battery can be directly obtained.
[0046] Next, this application takes the case where the lithium plating amount includes both reversible lithium plating amount and irreversible lithium plating amount as an example, and details the construction and actual application of the lithium plating model in two parts.
[0047] First, referring to Figure 3 , it is the detailed step flow chart for constructing the lithium plating model, which includes the following steps:
[0048] S101: Obtain the initial data of the lithium battery through the charging curve.
[0049] In step S101, the initial data includes the peak displacement reference value of the lithium battery based on the dV / dQ curve. Specifically, the peak displacement reference value includes the reference value L2_base representing the loss of the negative electrode active material and the reference value L3_base representing the loss of active lithium.
[0050] Specifically, the optional way to obtain the initial data of the lithium battery in step S101 is:
[0051] S1011: Provide two groups of test batteries Ai and Bi, and charge the test batteries Ai and Bi. Among them, i is the number of each group of test batteries.
[0052] S1012: Calculate the dV / dQ curve using the charging curve, and obtain the reference values L2_base and L3_base based on the dV / dQ curve.
[0053] It should be noted that the two groups of test batteries Ai and Bi are new batteries with the same performance specifications. Therefore, during the first charging of the two groups of test batteries Ai and Bi, the reference values L2_base and L3_base obtained based on their dV / dQ curves can be used as the initial reference reflecting the irreversible lithium plating amount.
[0054] In an implementation manner of the present application, when charging the test batteries Ai and Bi, the test batteries Ai and Bi should be charged to 100% SOC according to the slow charging strategy of the actual vehicle to obtain a complete charging curve and improve the reliability of the initial data.
[0055] In step S101, only one of the test batteries Ai or Bi can be charged from 0 to 100% SOC to obtain the reference values L2_base and L3_base. It is also possible to charge multiple or all of the test batteries Ai and / or Bi simultaneously, and improve the reliability of the reference values L2_base and L3_base through multiple measurements. For example, measure batteries A1, A2, A3... respectively, then measure batteries B1, B2, B3... respectively, and process all the data to filter out the obvious outlier data values to obtain the final reference values L2_base and L3_base.
[0056] S102: Obtain the test data of the lithium battery through the charging curve.
[0057] In step S102, the test data includes the peak displacement test values of the lithium battery based on the dV / dQ curve. Specifically, the peak displacement test values include the test value L2_i representing the loss of negative electrode active material and the test value L3_i representing the loss of active lithium.
[0058] Specifically, the optional method for obtaining the test data of the lithium battery in step S102 is to perform the following steps after step S1012:
[0059] S1021: Perform multiple cycle charge and discharge operations on the test batteries Ai and Bi respectively.
[0060] In step S1021, the number of charge-discharge cycles should be as many as possible, aiming at the number of charge-discharge cycles required for test batteries Ai and Bi to reach the maximum amount of lithium deposition. Moreover, the charge-discharge cycles should be carried out under different working conditions. For example, each charge-discharge cycle is carried out at different temperature values to simulate the low-temperature or high-temperature charging scenarios during the actual operation of the battery, or each charge-discharge cycle is carried out at different charging rates, or the SOC of the battery is different when each charge-discharge is completed to simulate overcharging or incomplete discharge situations.
[0061] For example, in an implementation manner of the present application, three influencing factors, namely temperature, charging rate, and the SOC of the battery when charging is completed, are used to exemplarily give the following several working conditions:
[0062] Working condition 1: The temperature of the battery is 25°C. Charge from 0 to 100% SOC according to the fast-charging map current, discharge at a constant current of 0.5C to 0% SOC, charge 7 times, and finally end with charging.
[0063] That is, test batteries A1 and B1 are subjected to 7 charge-discharge cycles under working condition 1.
[0064] Working condition 2: The temperature of the battery is 25°C. Charge from 0 to 100% SOC according to 1.5 times the fast-charging map current, discharge at a constant current of 0.5C to 0% SOC, charge 7 times, and finally end with charging.
[0065] That is, test batteries A2 and B2 are subjected to 7 charge-discharge cycles under working condition 2.
[0066] Working condition 3: The temperature of the battery is 25°C. Charge from 0 to 100% SOC according to 2 times the fast-charging map current, discharge at a constant current of 0.5C to 0% SOC, charge 7 times, and finally end with charging.
[0067] That is, test batteries A3 and B3 are subjected to 7 charge-discharge cycles under working condition 3.
[0068] Working condition 4: The temperature of the battery is 25°C. Charge from 0 to 102% SOC according to 2 times the fast-charging map current, discharge at a constant current of 0.5C to 0% SOC, charge 7 times, and finally end with charging.
[0069] That is, test batteries A4 and B4 are subjected to 7 charge-discharge cycles under working condition 4.
[0070] Working condition 5: The temperature of the battery is 25°C. Charge from 0 to 105% SOC according to 2 times the fast-charging map current, discharge at a constant current of 0.5C to 0% SOC, charge 7 times, and finally end with charging.
[0071] That is, test batteries A5 and B5 are subjected to 7 cycles of charge and discharge under operating condition 5.
[0072] Operating condition 6: The temperature at which the battery is located is 15°C. Charge from 0 to 105% SOC according to twice the current of the fast charge map, discharge at a constant current of 0.5C to 0% SOC, charge 7 times, and finally end with charging.
[0073] That is, test batteries A6 and B6 are subjected to 7 cycles of charge and discharge under operating condition 6.
[0074] Operating condition 7: The temperature at which the battery is located is 5°C. Charge from 0 to 105% SOC according to twice the current of the fast charge map, discharge at a constant current of 0.5C to 0% SOC, charge 7 times, and finally end with charging.
[0075] That is, test batteries A7 and B7 are subjected to 7 cycles of charge and discharge under operating condition 7.
[0076] Operating condition i: ……
[0077] It should be understood that the specific parameters of the operating conditions may include but are not limited to the above several forms. It can adjust any one or more of the three influencing factors, or rearrange the specific values corresponding to the three influencing factors to form new operating conditions, or add new influencing factors. The number of cycles of charge and discharge under each operating condition is not limited to 7 times. In order to make lithium plating more sufficient, it can also be 10 times or more.
[0078] In one implementation, the above operating conditions can be arranged in a trend of gradually increasing severity to simulate the degree of lithium plating of the battery under operating conditions of different severity.
[0079] S1022: After the last charge is completed during the charge and discharge cycle of test battery Bi, let it stand for a preset duration. And calculate the dV / dt curve during the standing process of test battery Bi through the charge curve, and obtain the time t_li corresponding to the minimum value of the dV / dt curve.
[0080] It should be noted that for reversible lithium plating, during the rest period after the battery is charged to a high SOC, due to the existence of the intercalation reaction, the reversible lithium plating part will exhibit an additional high-voltage plateau. This voltage plateau is reflected as a local minimum on the voltage differential dV / dt curve. According to the physical meaning reflected by the dV / dt curve, when a minimum value appears, it indicates that the intercalation reaction of lithium metal is approaching completion, that is, the reversible lithium plating part has been almost completely intercalated back into the charge-discharge cycle of the battery. Therefore, on the one hand, it can be judged whether reversible lithium plating occurs based on whether a minimum value appears on the dV / dt curve. On the other hand, when a minimum value appears, the amount of lithium that can be plated can be judged according to the time t_li when the minimum value appears. The later the time t_li when the minimum value appears, the longer the intercalation process, which means the more reversible lithium plating.
[0081] It should also be noted that the preset duration in the above step S1022 can be determined according to actual experience. Specifically, it should be greater than the shortest time for the minimum value to appear on the dV / dt curve.
[0082] S1023: After charging the test battery Bi, calculate the dV / dQ curve using the charging curve, and thus obtain the test value L2_i and the test value L3_i.
[0083] Specifically, after the rest of the test battery Bi is completed in step S1022, it is discharged to 0% SOC, and then charged to 100% SOC according to the slow charging strategy of the actual vehicle. Performing the above charging strategy on the test battery Bi is to ensure obtaining its complete dV / dQ curve, thereby improving the accuracy of the test value L2_i and the test value L3_i.
[0084] S103: Determine the first feature and the second feature.
[0085] In an embodiment of the present application, the first feature includes a first sub-feature representing the loss of the negative electrode active material of the lithium battery and a second sub-feature representing the loss of active lithium of the lithium battery, and the second feature represents the time corresponding to the appearance of a minimum value on the charging curve during the rest of the lithium battery.
[0086] Through the foregoing Figure 1 , it can be understood that the reference value L2_base, the test value L2_i, the reference value L3_base, and the test value L3_i reflect the amount of irreversible lithium plating. Therefore, the first sub-feature △L2 can be determined according to the test value L2_i and the reference value L2_base. Optionally, in a determination method of △L2 in the present application, △L2 = L2_i - L2_base. Similarly, the second sub-feature △L3 can be determined according to the test value L3_i and the reference value L3_base. In a determination method of △L3 in the present application, △L3 = L3_i - L2_base.
[0087] As can be seen from the above step S1022, t_li reflects the amount of irreversible lithium plating, so t_li is used as the second feature reflecting the amount of irreversible lithium plating.
[0088] S104: Determine the reversible lithium plating amount and irreversible lithium plating amount of the lithium battery by actual disassembly.
[0089] Specifically, step S104 includes:
[0090] S1041: After the last charge is completed during the cyclic charge and discharge of the test battery Ai, disassemble the test battery Ai and measure the total lithium plating amount m_li_all_i.
[0091] S1042: After the test battery Bi is charged based on the slow charge strategy of the actual vehicle and obtains the second feature t_li after the static stage, discharge the test battery Bi to 0% SOC, then disassemble it, and measure the irreversible lithium plating amount m_li_irrev_i of the test battery Bi.
[0092] S1043: Determine the reversible lithium plating amount m_li_rev_i according to the irreversible lithium plating amount m_li_irrev_i and the total lithium plating amount m_li_all_i, that is, m_li_rev_i = m_li_all_i - m_li_irrev_i.
[0093] Since the two groups of test batteries Ai and Bi are exactly the same, therefore, the total lithium plating amount m_li_all_i is obtained by disassembling the test battery Ai, the irreversible lithium plating amount m_li_irrev_i is obtained by disassembling the test battery Bi, and then the value of the reversible lithium plating amount m_li_rev_i is indirectly obtained through step S1043.
[0094] S105: Build a lithium plating model.
[0095] Based on the first sub-feature △L2, the second sub-feature △L3, and the irreversible lithium plating amount m_li_irrev_i, build the first expression of the lithium plating model f(△L2, △L3) = m_li_irrev_i.
[0096] As can be seen from the above steps, in the process of building the lithium plating model, the first expression is determined by performing cyclic charge and discharge and actual disassembly on two groups of test batteries.
[0097] Based on the reversible lithium plating amount m_li_rev_i and the second feature t_li, build the second expression of the lithium plating model f(t_li) = m_li_rev_i.
[0098] As can be seen from the above steps, in the process of building the lithium plating model, the second expression is also determined by performing cyclic charge and discharge and actual disassembly on two groups of test batteries.
[0099] It should be noted that the more test data collected in step S102, the higher the reliability of the final obtained lithium deposition model. For example, by conducting tests on test battery A1 and test battery B2 under a working condition, a set of mapping relationships between △L2_1, △L3_1 and m_li_irrev_1 are obtained. The more working conditions, the more mapping relationships between △L2_1, △L3_1 and m_li_irrev_1 are obtained, the more comprehensive the data, and the higher the reliability of the first expression f(△L2, △L3) = m_li_irrev_i finally obtained after data processing.
[0100] Refer to Figure 4 , which is a detailed step flowchart of the method for detecting the lithium deposition amount of a lithium battery based on steps 2 and 3, and includes the following steps:
[0101] S201: Charge the battery under test to 100% SOC based on the real vehicle slow charging strategy.
[0102] S202: Obtain the charging curve of the battery under test and calculate the dV / dQ curve.
[0103] S203: Extract the actual value L2 and the actual value L3 from the dV / dQ curve, and calculate △L2 based on the actual value L2 and the reference value L2_base, and calculate △L3 based on the actual value L3 and the reference value L3_base.
[0104] As can be seen from step S203, in the process of detecting the lithium deposition amount of a lithium battery, the first sub-feature and the second sub-feature are obtained through the charging curve of the lithium battery.
[0105] S204: Calculate the irreversible lithium deposition amount according to the first expression f(△L2, △L3) = m_li_irrev_i.
[0106] S205: After the battery under test is charged, obtain the dV / dt curve during its static period and record the time t_li corresponding to the minimum value of the dV / dt curve.
[0107] S206: Calculate the reversible lithium deposition amount according to the second expression f(t_li) = m_li_rev_i.
[0108] In practical applications, the ratio of reversible lithium deposition to irreversible lithium deposition can also be calculated according to the calculation results of step S204 and step S206.
[0109] This application combines two methods, namely lossy detection and non-destructive detection, to construct a lithium plating model by combining the charging curve and the actual disassembly method. Based on the charging curve, the first sub-feature △L2, the second sub-feature △L3, and the second feature t_li reflecting irreversible lithium plating of the lithium battery are obtained. Then, by actually disassembling the battery, the irreversible lithium plating amount m_li_irrev_i and the reversible lithium plating amount m_li_rev_i are obtained. Thus, experiments are carried out under various working conditions respectively to establish the mapping relationship between △L2, △L3 and m_li_irrev_i, and the mapping relationship between t_li and m_li_rev_i, so as to obtain the lithium plating model. Therefore, during subsequent in-vehicle operation or battery production and R & D process, the current values of the above features can be obtained from the charging curve of the battery to be tested, and the current values are directly input into the lithium plating model to obtain the reversible lithium plating amount and the irreversible lithium plating amount of the battery to be tested.
[0110] Through the construction of the lithium plating model in the early stage, when detecting the lithium plating amount of the battery in the later stage, on the one hand, there is no need to disassemble the battery, which retains the integrity of the battery. On the other hand, through the lithium plating model, the reversible lithium plating amount and the irreversible lithium plating amount of the battery can be quantitatively detected at the same time, so as to reflect the actual problems of the battery. This has important reference significance for adjusting the battery management strategy and improving the battery structure. Therefore, by establishing a lithium plating model to distinguish the reversible lithium plating amount and the irreversible lithium plating amount, and calculating parameters such as the ratio and total amount of the two, it is not only beneficial to the real-time detection during in-vehicle operation, but also can obtain the required lithium plating parameters in real time during the design and R & D link of the battery to reflect the problems of the battery, and then adjust the corresponding structure of the battery to obtain a battery product with better performance. Therefore, the method of this application has important engineering significance both for in-vehicle operation and in design and R & D.
[0111] Furthermore, this application also discloses a detection device for the lithium plating amount of a lithium battery, which includes a detection module and a lithium plating amount determination module. Among them, the detection module is used to detect the current value of the target feature during the application of the lithium battery. The lithium plating amount determination module is used to input the current value into the lithium plating model to determine the lithium plating amount of the lithium battery. In some embodiments, the detection module and the lithium plating amount determination module can be combined into one module.
[0112] The above detection device for the lithium plating amount of a lithium battery is used to execute Figure 2 and Figure 4 the embodiments of the detection method for the lithium plating amount of a lithium battery shown. The technical principles, the technical problems solved and the technical effects produced by the two are similar. Those skilled in the art of this technology can clearly understand that for the convenience and conciseness of description, the specific working process and related descriptions of the detection device for the lithium plating amount of a lithium battery can refer to the content described in the embodiments of the detection method for the lithium plating amount of a lithium battery, which will not be elaborated here.
[0113] Those skilled in the art can understand that all or part of the processes in the methods of the above-mentioned embodiments of the present application can also be completed by instructing relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-mentioned method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable storage medium can include: any entity or device, medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal, telecommunication signal, and software distribution medium that can carry the computer program code. It should be noted that the content included in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.
[0114] Furthermore, the present application also discloses a computer device, which includes a processor and a storage device. The storage device is adapted to store multiple program codes, and the program codes are adapted to be loaded and run by the processor to execute the detection method described in any one of the above method embodiments. For the sake of convenience of description, only the parts related to the embodiments of the present application are shown. For the specific technical details not disclosed, please refer to the method embodiment part of the present application. The computer device can be a computer device formed by various electronic devices.
[0115] Furthermore, the present application also discloses a computer-readable storage medium. In an embodiment of the computer-readable storage medium according to the present application, the computer-readable storage medium can be configured to store a program for executing the detection method of the lithium deposition amount of the lithium battery in the above method embodiment. The program can be loaded and run by a processor to implement the above detection method. For the sake of convenience of description, only the parts related to the embodiments of the present application are shown. For the specific technical details not disclosed, please refer to the method embodiment part of the present application. The computer-readable storage medium can be a storage device formed by various electronic devices. Optionally, the computer-readable storage medium in the embodiments of the present application is a non-transitory computer-readable storage medium.
[0116] Furthermore, it should be understood that since the setting of each module is only for explaining the functional units of the device of the present application, the physical devices corresponding to these modules can be the processor itself, or a part of the software in the processor, a part of the hardware, or a part of the combination of software and hardware. Therefore, the number of each module in the figure is only illustrative.
[0117] Those skilled in the art can understand that the various modules in the device can be adaptively split or combined. Such splitting or combining of specific modules will not cause the technical solution to deviate from the principle of this application. Therefore, the technical solutions after splitting or combining will all fall within the protection scope of this application.
[0118] So far, the technical solution of this application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of this application is obviously not limited to these specific embodiments. Without departing from the principle of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this application.
Claims
1. A method for detecting the amount of lithium plating in a lithium battery, characterized in that, Comprising: During the application process of the lithium battery, detecting the current value of the target feature; Inputting the current value into the lithium plating model to determine the lithium plating amount of the lithium battery; Wherein, the lithium plating model reflects the mapping relationship between the target feature of the lithium battery and the lithium plating amount, and the target feature includes a first feature representing the irreversible lithium plating amount and / or a second feature representing the reversible lithium plating amount.
2. The detection method according to claim 1, characterized in that, The first feature includes a first sub-feature representing the loss of the negative electrode active material of the lithium battery and a second sub-feature representing the loss of the active lithium of the lithium battery; The first sub-feature and the second sub-feature are obtained through the charge curve of the lithium battery.
3. The detection method according to claim 2, characterized in that, The lithium plating model includes a first expression constructed based on the first sub-feature, the second sub-feature, and the irreversible lithium plating amount.
4. The detection method according to claim 3, characterized in that, The first expression is determined by performing cyclic charge and discharge and actual disassembly on two groups of test batteries.
5. The detection method according to claim 1, characterized in that, The second feature represents the time corresponding to the minimum value based on the charge curve during the static process of the lithium battery.
6. The detection method according to claim 5, characterized in that, The lithium plating model includes a second expression constructed based on the second feature and the reversible lithium plating amount.
7. The detection method according to claim 6, characterized in that, The second expression is determined by performing cyclic charge and discharge and actual disassembly on two groups of test batteries.
8. A detection device for the amount of lithium plating in a lithium battery, characterized in that, Comprising: A detection module, which is used to detect the current value of the target feature during the application process of the lithium battery; A lithium plating amount determination module, which is used to input the current value into the lithium plating model to determine the lithium plating amount of the lithium battery.
9. A computer device, including a processor and a storage device, the storage device being adapted to store multiple program codes, characterized in that, The program code is suitable for being loaded and run by the processor to execute the detection method according to any one of claims 1 to 7.
10. A computer-readable storage medium, in which multiple program codes are stored, characterized in that, The program code is suitable for being loaded and run by the processor to execute the detection method according to any one of claims 1 to 7.