A targeted relaxation repair method and system for lithium battery lithium plating

Abstract

This invention discloses a targeted relaxation repair method and system for lithium-ion batteries after lithium plating. The method includes: collecting voltage, current, and time data of the lithium-ion battery during charging, discharging, and relaxation processes; extracting lithium plating-related voltage characteristic parameters and determining whether the battery is in a recoverable lithium plating state; calculating the voltage relaxation completion rate during the relaxation stage and determining the characteristic relaxation time to reach a preset completion ratio; determining the target relaxation duration based on the characteristic relaxation time and controlling the battery to perform targeted relaxation repair. This method can identify the recoverable window after lithium plating using voltage signals and select the relaxation time based on relaxation kinetics, promoting the re-intercalation or redistribution of deposited lithium, reducing insufficient recovery caused by excessively short relaxation and interface passivation and deactivation caused by excessively long relaxation. It can be applied to scenarios such as lithium-ion batteries, battery management systems, new energy vehicles, and energy storage systems.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery management and lifespan repair technology, and relates to a relaxation time repair method, specifically a targeted relaxation repair method and system for lithium battery after lithium plating. Background Technology

[0002] Lithium-ion batteries are widely used in new energy vehicles, energy storage systems, and portable electronic devices due to their high energy density, long cycle life, and excellent power performance. With the increasing demand for fast charging and high-power applications, lithium metal deposition, known as lithium plating, may occur on the negative electrode surface during high-rate charging, low-temperature charging, high-state-of-charge charging, or post-aging charging. Lithium plating depletes the active lithium reserve, increases interfacial impedance, induces capacity decay, and may form dendritic deposits, posing safety risks.

[0003] Existing technologies mainly focus on the detection, early warning, and charging rate limitation of lithium plating. Lithium plating risks are identified through methods such as voltage relaxation, differential voltage, impedance tracking, or temperature response; or the probability of lithium plating is reduced by lowering the charging rate, lowering the charging cut-off voltage, or extending the resting time. However, these methods typically have the following shortcomings: First, they mainly focus on whether lithium plating has occurred, lacking a determination of the recoverable state after plating; second, the relaxation time is mostly fixed and cannot be adaptively adjusted according to the stage of lithium plating and the battery state; third, excessively short relaxation may lead to insufficient re-intercalation or redistribution of deposited lithium, while excessively long relaxation may promote interface passivation, side reactions, and the formation of dead lithium; fourth, there is a lack of targeted relaxation repair processes that can be directly embedded into the battery management system.

[0004] After lithium plating occurs, some deposited lithium is not immediately deactivated but may remain in a recoverable state. Within an appropriate relaxation time, the local electric field and ion concentration gradient can redistribute, allowing some metallic lithium to re-intercalate or transform into a more recoverable state. However, when the relaxation time is too long, electrolyte decomposition, solid electrolyte interfacial film thickening, and electron disconnection may continue to occur on the lithium surface, leading to the conversion of recoverable lithium into irrecoverable lithium. Therefore, a repair method is urgently needed that can identify the recoverable window after lithium plating and determine the target relaxation time based on voltage relaxation kinetics. Summary of the Invention

[0005] To address the shortcomings of existing technologies, such as the lack of state determination after lithium plating, the lack of basis for relaxation time selection, and the difficulty in balancing recovery efficiency and side reaction suppression with fixed relaxation strategies, this invention provides a targeted relaxation repair method and system for lithium batteries after lithium plating. By extracting lithium plating-related voltage characteristics, the recoverable state after lithium plating is determined, and the target relaxation time is determined based on the voltage relaxation completion rate. This promotes the re-intercalation or redistribution of deposited lithium while reducing interface passivation and deactivation caused by long-term relaxation. This invention is applicable to the determination of the state, relaxation time selection, and cycle life improvement of lithium batteries after lithium plating during fast charging, low-temperature charging, high-rate cycling, overcharge recovery, or aging service. It can be widely used in new energy vehicles, energy storage power stations, consumer electronics, power tools, and battery management systems.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A targeted relaxation repair method for lithium-ion batteries after lithium plating includes the following steps:

[0008] Step S1: Collect voltage, current and time data of the lithium battery during charging, discharging and / or relaxation processes;

[0009] Step S2: Extract lithium plating-related voltage characteristic parameters based on voltage, current, and time data;

[0010] Step S3: Determine whether the lithium battery is in a recoverable lithium plating state based on the lithium plating-related voltage characteristic parameters.

[0011] Step S4: When the lithium battery is in a recoverable lithium plating state, calculate the voltage relaxation completion based on the voltage change during the relaxation phase.

[0012] Step S5: Determine the characteristic relaxation time corresponding to when the voltage relaxation completion rate reaches the preset completion ratio;

[0013] Step S6: Determine the target relaxation time based on the characteristic relaxation time, and control the lithium battery to perform the relaxation operation for the target relaxation time.

[0014] A targeted relaxation repair system for lithium-ion batteries after lithium plating, implementing the above method, includes a data acquisition module, a lithium plating feature extraction module, a recoverable state determination module, a voltage relaxation completion calculation module, a target relaxation duration determination module, and a charge / discharge control module, wherein:

[0015] The data acquisition module is used to collect battery voltage, current, and time data;

[0016] The lithium plating feature extraction module is used to extract lithium plating-related voltage feature parameters;

[0017] The recoverable state determination module is used to determine whether the battery is in a lithium plating recoverable state.

[0018] The voltage relaxation completion calculation module is used to calculate the voltage relaxation completion.

[0019] The target relaxation duration determination module is used to determine the target relaxation duration;

[0020] The charge / discharge control module is used to control the battery to perform targeted relaxation repair operations.

[0021] The application of the above-mentioned targeted relaxation repair method after lithium plating in lithium batteries, battery management systems, new energy vehicles, energy storage power stations, consumer electronic devices or power tools.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. This invention does not use a fixed relaxation time, but determines the target relaxation time based on the degree of voltage relaxation completion, and can achieve adaptive repair according to the lithium plating state and battery state.

[0024] 2. This invention combines the determination of lithium plating state with the selection of relaxation time, which can distinguish the recoverable window and deactivation tendency of lithium, avoid insufficient recovery caused by too short relaxation, and also avoid side reactions and enhanced passivation caused by too long relaxation.

[0025] 3. This invention uses data that can be directly obtained by the battery management system, such as voltage, current and time, without changing the battery structure, and has strong engineering adaptability.

[0026] 4. This invention can be applied to pouch batteries, cylindrical batteries, square batteries, battery modules and battery packs, and is suitable for application scenarios such as new energy vehicles, energy storage power stations, consumer electronics and power tools. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the targeted relaxation repair method after lithium plating in lithium batteries.

[0028] Figure 2 This is a schematic diagram of the extraction of lithium plating-related voltage characteristic parameters.

[0029] Figure 3 It is the voltage relaxation completion R(t) and the characteristic relaxation time t α A schematic diagram for determining the [specific element].

[0030] Figure 4 This is a schematic diagram comparing the electrochemical recovery results under different relaxation protocols.

[0031] Figure 5 This is a comparison chart of 18650 batteries after relaxation repair and cycle testing.

[0032] Figure 6This is a schematic diagram of the hierarchical module structure of the targeted relaxation repair system. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0034] This invention provides a targeted relaxation repair method for lithium-ion batteries after lithium plating. The method includes: collecting voltage, current, and time data of the lithium-ion battery during charging, discharging, and relaxation processes; extracting lithium plating-related voltage characteristic parameters and determining whether the battery is in a recoverable lithium plating state; calculating the voltage relaxation completion rate during the relaxation stage and determining the characteristic relaxation time to reach a preset completion ratio; determining the target relaxation duration based on the characteristic relaxation time and controlling the battery to perform targeted relaxation repair. This method can use voltage signals to identify the recoverable window after lithium plating and select the relaxation time according to relaxation kinetics, promoting the re-intercalation or redistribution of deposited lithium, reducing insufficient recovery caused by excessively short relaxation and interface passivation and deactivation caused by excessively long relaxation. It can be applied to scenarios such as lithium-ion batteries, battery management systems, new energy vehicles, and energy storage systems. Figure 1 As shown, the specific steps are as follows:

[0035] Step S1, Lithium plating induction or lithium plating identification: Charge, discharge, high-rate cycling, low-temperature charging or other operating conditions that may induce lithium plating on the lithium battery, and collect data on battery voltage, current, time, temperature, state of charge or health status; determine whether lithium plating has occurred or is suspected to have occurred in the battery based on the voltage, current and time data.

[0036] Step S2, Lithium Plating State Feature Extraction: Extract lithium plating-related voltage feature parameters based on the collected data. These parameters include one or more of the following: pre-nucleation hysteresis time, lithium plating plateau capacity, relaxation response area, low-potential charging stripping / re-intercalation related capacity, voltage differential characteristics, voltage plateau duration, and voltage plateau area. The pre-nucleation hysteresis time is the time elapsed from the start of the lithium intercalation process to the first attainment of the preset lithium plating threshold. The lithium plating plateau capacity is the integral current capacity within the range where the battery electrode voltage is below the preset lithium plating threshold. The relaxation response area is the area between the relaxation stage reference voltage and the relaxation stage voltage curve. The reference voltage is the mean, median, steady-state fit value, or robust statistical value of the voltage within the preset time window at the end of the relaxation stage. The low-potential charging stripping / re-intercalation related capacity is the integral current capacity of the battery during the constant current charging stage from the start of charging until the voltage first reaches the preset low-potential threshold. The preset low-potential threshold is 0.05V to 0.30V relative to the lithium / lithium-ion reference electrode.

[0037] Step S3, Lithium Plating Recoverable State Determination: Determine whether the battery is currently in a lithium plating recoverable state based on lithium plating-related voltage characteristic parameters. The lithium plating recoverable state refers to a state in which metallic lithium has been formed or is suspected to have formed in the battery, and the deposited lithium still has the ability to re-intercalate, redistribute, or reversibly strip, and has not yet completely transformed into an irrecoverable deactivated lithium state.

[0038] Step S4, Voltage Relaxation Completion Calculation: When the battery is in a lithium plating recoverable state, the battery enters the relaxation stage, and the voltage relaxation completion R(t) is calculated:

[0039] R(t) = [V(t) - V0] / [V ref -V0]

[0040] Where V0 is the relaxation start voltage, V(t) is the voltage at relaxation time t, and V ref R is the relaxation reference voltage, and R(t) is the degree of voltage relaxation completion at time t.

[0041] The relaxation reference voltage is the mean, median, steady-state fitted value, or exponential fitted extrapolation value of the voltage within a preset time window at the end of the relaxation stage. The recoverable lithium plating state satisfies at least one of the following conditions: the lithium plating platform capacity is within a preset range; the relaxation response area is within a preset range; the low-potential charging stripping / re-intercalation related capacity begins to appear but does not exceed the deactivation threshold; the pre-nucleation hysteresis time decreases to a preset range; or the classification result corresponding to the combination of lithium plating related voltage characteristic parameters is a recoverable lithium plating state.

[0042] Step S5, Target Relaxation Time Determination: Determine the characteristic relaxation time t corresponding to when the voltage relaxation completion rate reaches the preset completion ratio α. α :

[0043] t α =min{t:R(t)≥α}

[0044] Wherein, α is the preset relaxation completion ratio, which ranges from 30% to 90%, preferably from 50% to 70%, and more preferably from 60%.

[0045] Step S6, Targeted Relaxation Repair: Based on Feature Relaxation Time t α A target relaxation time is determined, and the battery is controlled to perform relaxation operations within the target relaxation time, so that deposited lithium is repaired within the time window when beneficial re-intercalation or redistribution processes dominate. The target relaxation time is the characteristic relaxation time, a multiple of the characteristic relaxation time, or a time corrected by combining the characteristic relaxation time with temperature, rate, state of charge, health status, and safety constraints.

[0046] Step S7, Subsequent Charge / Discharge or Application Control: After the target relaxation is completed, control the battery to continue to perform charging, discharging, fast charging, maintenance cycle, capacity recovery or life optimization programs, and evaluate the targeted relaxation repair effect based on subsequent voltage, current, impedance, capacity retention rate or disassembly characterization results.

[0047] This invention also discloses a targeted relaxation repair system for lithium-ion batteries after lithium plating, such as... Figure 6 As shown, the system includes a data acquisition module, a lithium plating feature extraction module, a recoverable state determination module, a voltage relaxation completion calculation module, a target relaxation duration determination module, and a charge / discharge control module. Specifically: the data acquisition module collects battery voltage, current, and time data; the lithium plating feature extraction module extracts lithium plating-related voltage characteristic parameters; the recoverable state determination module determines whether the battery is in a recoverable lithium plating state; the voltage relaxation completion calculation module calculates the voltage relaxation completion; the target relaxation duration determination module determines the target relaxation duration; and the charge / discharge control module controls the battery to perform targeted relaxation repair operations. These modules work collaboratively to automate the entire process from lithium plating state identification and relaxation time calculation to targeted relaxation control. The system can be integrated into battery management systems, charge / discharge testing platforms, energy storage control systems, or electric vehicle control systems.

[0048] This invention relates to a method applicable to at least one of lithium batteries, battery management systems, new energy vehicles, energy storage power stations, consumer electronic devices, or power tools; the lithium batteries include, but are not limited to, lithium-ion batteries, lithium metal batteries, and rechargeable batteries with lithium-containing electrode systems; the negative electrode material includes graphite, silicon-carbon composite materials, lithium metal, hard carbon, lithium titanate, or combinations thereof; the positive electrode material includes lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or other lithium-containing positive electrode materials; the battery form includes pouch batteries, cylindrical batteries, prismatic batteries, battery modules, or battery packs.

[0049] Example 1

[0050] This embodiment provides a method for determining the recoverable state of lithium plating and the targeted relaxation time using a graphite half-cell. This method is used to extract lithium plating evolution characteristics from the half-cell voltage fingerprint and determine the target relaxation time based on the voltage relaxation completion.

[0051] In this embodiment, a Li||graphite half-cell is assembled using lithium metal as the counter electrode and graphite as the working electrode. The graphite electrode can be prepared by coating a mixture of graphite active material, conductive agent, and binder onto a copper foil current collector. The mass ratio of the graphite active material, conductive agent, and binder can be 90:5:5 or 95:2:3. The solvent can be N-methylpyrrolidone or a deionized water system. After coating, the working electrode is obtained through drying, rolling, and cutting. The separator, electrolyte, and lithium sheet can use commonly used half-cell assembly materials in the art. Battery assembly is completed in an inert atmosphere glove box. After half-cell assembly, it is pre-cycled at a low rate for 2 to 5 cycles to stabilize the electrode interface and initial irreversible capacity.

[0052] During testing, the half-cell was subjected to a series of steps: constant current discharge, main relaxation, constant current charging, and subsequent resting. For Li||graphite half-cells, constant current discharge corresponds to the lithium intercalation process at the graphite working electrode, and lithium plating may occur under conditions of over-intercalation; constant current charging corresponds to the lithium deintercalation process at the graphite working electrode, which may be accompanied by the reintercalation, stripping, or residual low potential response of deposited lithium. The test system records the cycle number, step number, step type, time, current, and voltage in real time, with sampling intervals ranging from 1 s to 10 s.

[0053] A constant-current discharge was used to induce the graphite electrode to enter a low-potential region, followed by a main relaxation period of approximately 10800 s, and then constant-current charging to the preset cutoff voltage. Sampling data covered multiple consecutive cycles, such as more than 60 cycles, to obtain the pre-nucleation hysteresis time t. nuc Lithium plating platform capacity Q plate Relaxation response area A relax Low-potential charge stripping / re-embedding related capacity Q strip and characteristic relaxation time t 60 The evolution follows the cycle. The aforementioned current, cutoff potential, relaxation time, and number of cycles can be adjusted according to the graphite loading, electrode area, battery capacity, and severity of lithium plating.

[0054] Step S1: Extract the pre-nucleation lag time t nuc .like Figure 2 As shown, in the constant current discharge phase of each cycle, the time when the voltage first reaches the preset lithium plating threshold is recorded. For graphite half-cells, the preset lithium plating threshold can be selected as 0V vs. Li / Li+. If two adjacent sampling points cross 0V, the crossing time is determined by linear interpolation. This time is defined as the pre-nucleation lag time t. nuc , used to characterize the time required from the start of lithium intercalation to entering the lithium plating-related potential range. As the cycle progresses, if t nuc The gradual shortening indicates that the battery enters the low potential range related to lithium plating earlier.

[0055] Step S2: Extract the lithium plating platform capacity Q plate In the constant current discharge phase of each cycle, current integration is performed on the interval where the voltage is lower than the preset lithium plating threshold to obtain the lithium plating plateau capacity Q. plate The calculation formula is Q plate =(1000 / 3600)∫|I(t)|dt, the integration interval is V<0. Q plate Used to characterize the capacity after entering the low potential range associated with lithium plating. If Q plate As the cycle length gradually increases, it indicates that the capacity of the lithium plating-related platform is enhanced.

[0056] Step S3: Extract the relaxation response area A relax During the main relaxation phase after constant current discharge, the voltage statistical value within a preset time window at the end of the relaxation is selected as the reference voltage V. ref The statistical value can be the mean, median, or robust statistical value of the voltage over the last 5 seconds to 300 seconds. In this embodiment, the median voltage over the last 30 seconds of relaxation can be used as V. ref And calculate A relax =∫max(0,V ref To compare the response intensity under different relaxation times, A can be further calculated. relax / t rest , where t rest A_relax represents the total relaxation time. It is used to characterize the voltage relaxation response strength and recoverable window characteristics after lithium plating.

[0057] Step S4: Extract the low-potential charge stripping / re-embedding related capacity Q strip During the constant current charging phase, the capacity from the start of charging until the voltage first reaches the preset low potential threshold is integrated to obtain Q. strip The preset low potential threshold can be determined according to the battery system, for example, 0.05V to 0.30V vs. Li / Li+; in this embodiment, it can be selected as 0.150V vs. Li / Li+. strip Used to characterize residual low-potential capacity that still needs to be stripped or re-inserted during the charging phase after relaxation.

[0058] Step S5: Determine the recoverable state of lithium plating. Based on t nuc Q plate A relax and Q strip The cyclic evolution of the battery is divided into four stages: lithium intercalation-dominated stage, lithium nucleation stage, lithium growth stage, charging stage (exfoliation / reintercalation signal appearance stage), and deactivated lithium-dominated stage. When Q... plate A has already appeared and is gradually increasing. relax Maintain a strong relaxation response, Q stripWhen lithium deposition first appears or is at a low level, the battery is considered to be in a recoverable lithium deposition state. This state indicates that the deposited lithium has not been completely deactivated and still has the potential to be re-intercalated, redistributed, or recovered with low damage through relaxation.

[0059] Step S6: Determine the target relaxation time. For example... Figure 3 As shown, in the relaxation curve corresponding to the recoverable state of lithium plating, the relaxation start voltage is taken as V0, and the relaxation end reference voltage is taken as V. ref Calculate the voltage relaxation completion degree R(t) = [V(t) - V0] / [V ref -V0]. Determine the time t when R(t) reaches the preset completion ratio alpha. α In this embodiment, α is set to 60%, corresponding to t60. t is calculated for multiple cycles within the recoverable lithium plating window. 60 , to obtain t 60 The relaxation time is concentrated around 1 hour, so approximately 1 hour is selected as the short-term targeted relaxation time. This time is used to capture the beneficial processes in the early stage of relaxation, which are mainly characterized by lithium re-intercalation, ion concentration redistribution, and interfacial polarization release, rather than pursuing complete relaxation to the long-term tail.

[0060] Step S7: Compare different relaxation protocols. Under the same lithium plating induction conditions, set up a no-relaxation group, a short-time relaxation group, and a long-time relaxation group. The no-relaxation group directly enters the subsequent constant current charging after lithium plating; the short-time relaxation group relaxes for about 1 hour after lithium plating; the long-time relaxation group relaxes for significantly longer than t after lithium plating. 60 The time was set to, for example, 20 hours. Subsequently, all groups performed the same constant current charging conditions, with the charging cutoff voltage, charging current, and final sample desampling state remaining consistent.

[0061] Step S8: Verify the repair effect. For example... Figure 4 As shown, the electrochemical repair effects of different relaxation protocols can be compared by measuring charging low-potential capacity, capacity recovery rate, polarization change, or subsequent charging curves. If the short-time relaxation group exhibits a lower residual Q... strip Higher capacity recovery and smaller polarization growth indicate that the target relaxation time can reduce the impact of residual lithium deposits after relaxation on subsequent charging.

[0062] Example 2

[0063] This embodiment provides a scheme for verifying the application effect of the targeted relaxation repair method using commercial 18650 lithium batteries, which can extend from the mechanism identification of graphite half-cells to the engineering control of commercial cylindrical batteries.

[0064] In this embodiment, commercial 18650 lithium batteries from the same batch are selected. The battery can be a cylindrical battery composed of a graphite anode and lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or other lithium-containing transition metal oxide cathodes. Commercial full cells do not directly expose the potential of the graphite anode relative to Li / Li+. Therefore, terminal voltage, charge / discharge current, time, temperature, state of charge, health status, and historical cycle information are used as input signals. The lithium plating risk range and targeted relaxation time are determined by combining half-cell calibration, disassembly verification, or empirical mapping relationships.

[0065] Step S1: Battery Screening and Pretreatment. 18650 batteries with similar capacity, internal resistance, and open-circuit voltage were selected as test subjects. At room temperature, 2 to 3 charge-discharge cycles were performed at a low rate to stabilize the battery state; the baseline capacity, DC internal resistance, open-circuit voltage curves, temperature rise curves, and initial health status were recorded. After pretreatment, the batteries were divided into three groups: no-relaxation group, targeted relaxation group, and long-term relaxation group. Each group could have at least two parallel samples, and the initial capacity, internal resistance, and health status of the batteries in each group were kept similar.

[0066] Step S2: Establish a full-cell voltage relaxation reference. Perform short-term interruption or resting tests on the 18650 battery at different charging rates, states of charge, and temperatures, and collect relaxation curves of the terminal voltage over time. Calculate the voltage relaxation completion degree R(t) based on the terminal voltage relaxation curves, where V0 is the terminal voltage at the start of resting, and V... ref V(t) is the reference terminal voltage at the end of the resting period, and V(t) is the terminal voltage at time t after resting. By comparing the results with the graphite half-cell test results in Example 1, a mapping relationship between the full cell terminal voltage relaxation characteristics and the recoverable state of lithium plating on the negative electrode is established.

[0067] Step S3: Perform lithium plating-induced or fast-charge cycling. Perform fast-charge or high-rate cycling on each group of 18650 batteries at the same temperature and charging rate, such as using a 2C charging rate or other charging regimes that can induce lithium plating risk. During charging, collect terminal voltage, current, temperature, and time data in real time, and determine whether the battery has entered a recoverable window after lithium plating by analyzing terminal voltage relaxation characteristics, capacity decay trends, polarization growth, internal resistance changes, or a preset lithium plating risk model.

[0068] Step S4: Execute different relaxation protocols. When the battery enters the recoverable window after lithium plating, the non-relaxation group does not insert an additional rest period; the targeted relaxation group inserts a target relaxation time determined according to the voltage relaxation completion rate, for example, t. 60 The corresponding relaxation time is approximately 1 hour; the long relaxation group has a resting time significantly longer than the target relaxation time, such as 20 hours. After relaxation is completed, each group continues to charge, discharge or cycle according to the same protocol to ensure that the charging rate, discharging rate, cutoff voltage, ambient temperature and cycling regime are consistent except for the relaxation time.

[0069] Step S5: System Execution and Control. For example... Figure 6 As shown, the targeted relaxation repair system may include a sensing layer, an algorithm decision layer, and an execution control layer. The sensing layer is used to collect terminal voltage, current, temperature, time, SOC, and SOH data and perform filtering, anomaly removal, step identification, and cyclic segmentation. The algorithm decision layer is used to analyze the voltage fingerprint, determine whether lithium plating is not present, recoverable, or severely plating, and based on R(t) and t... α or t 60 Output target relaxation time; the execution control layer is used to output interrupted charging, idle charging, resume charging, derating, safety protection or abnormal alarm commands to the BMS, charging equipment, vehicle controller or energy storage EMS.

[0070] Step S6: Cyclic performance verification. For example... Figure 5 As shown, continuous cycling tests were performed on each group of 18650 batteries, recording capacity retention, coulombic efficiency, charge / discharge polarization, DC internal resistance, AC impedance, or temperature rise changes. In one embodiment, a long cycling regime of 2C charging and constant current discharging can be used, with a low-rate capacity calibration performed every few cycles. If the targeted relaxation group exhibits lower capacity decay and slower polarization growth compared to the non-relaxed group, while exhibiting higher capacity retention and smaller impedance growth compared to the long-time relaxation group, it indicates that the targeted relaxation repair method can improve the cycle life of commercial cylindrical batteries.

[0071] Step S7: Disassembly and Post-Analysis Verification. After the cycle is complete, some 18650 batteries can be disassembled in an inert atmosphere, and the negative electrode sheet can be removed for surface morphology, interface chemistry, and structural analysis. The analysis may include scanning electron microscopy, X-ray photoelectron spectroscopy, three-dimensional nanoCT, or other characterization methods. If the targeted relaxation group exhibits less residual deposition, lower organic by-reaction products, a milder passivation layer, and a more uniform electrode structure, it further demonstrates that the targeted relaxation repair method can reduce irreversible damage after lithium plating.

[0072] This embodiment demonstrates that the method is not only applicable to determining the recoverable lithium plating window and t60 in Li||graphite half-cells, but can also be applied to commercial 18650 lithium batteries as a life restoration strategy under fast charging or high-rate cycling. This method can be executed by a battery management system or an external charging control device without altering the battery's internal structure, thus demonstrating engineering feasibility.

Claims

1. A targeted relaxation repair method for lithium-ion batteries after lithium plating, characterized in that... The method includes the following steps: Step S1: Collect voltage, current and time data of the lithium battery during charging, discharging and / or relaxation processes; Step S2: Extract lithium plating-related voltage characteristic parameters based on voltage, current, and time data; Step S3: Determine whether the lithium battery is in a recoverable lithium plating state based on the lithium plating-related voltage characteristic parameters. Step S4: When the lithium battery is in a recoverable lithium plating state, calculate the voltage relaxation completion based on the voltage change during the relaxation phase. Step S5: Determine the characteristic relaxation time corresponding to when the voltage relaxation completion rate reaches the preset completion ratio; Step S6: Determine the target relaxation time based on the characteristic relaxation time, and control the lithium battery to perform the relaxation operation for the target relaxation time.

2. The targeted relaxation repair method for lithium battery after lithium plating according to claim 1, characterized in that... The specific steps of step S1 are as follows: the lithium battery is charged, discharged, subjected to high-rate cycling, low-temperature charging or other conditions that may induce lithium plating, and the battery's voltage, current, time, temperature, state of charge or health data are collected; based on the voltage, current and time data, it is determined whether the battery has or is suspected of having lithium plating.

3. The targeted relaxation repair method for lithium battery after lithium plating according to claim 1, characterized in that... In step S2, the lithium plating-related voltage characteristic parameters include one or more of the following: pre-nucleation hysteresis time, lithium plating plateau capacity, relaxation response area, low-potential charging stripping / re-intercalation related capacity, voltage differential characteristics, voltage plateau duration, and voltage plateau area.

4. The targeted relaxation repair method after lithium plating in lithium batteries according to claim 1, characterized in that... In step S4, the formula for calculating the voltage relaxation completion degree is: R(t)=[V(t)-V0] / [V ref -V0] Where V0 is the relaxation start voltage, V(t) is the voltage at relaxation time t, and V ref R is the relaxation reference voltage, and R(t) is the degree of voltage relaxation completion at time t.

5. The targeted relaxation repair method for lithium battery after lithium plating according to claim 1, characterized in that... In step S4, the recoverable lithium plating state satisfies at least one of the following conditions: the lithium plating platform capacity is within a preset range; the relaxation response area is within a preset range; the low-potential charging stripping / re-intercalation related capacity begins to appear but does not exceed the deactivation threshold; the pre-nucleation hysteresis time decreases to a preset range; or the classification result corresponding to the combination of lithium plating related voltage characteristic parameters is a recoverable lithium plating state.

6. The targeted relaxation repair method after lithium plating in lithium batteries according to claim 1, characterized in that... In step S5, the formula for calculating the characteristic relaxation time is: t α =min{t:R(t)≥α} Among them, t α The characteristic relaxation time is α, which is the preset relaxation completion ratio, ranging from 30% to 90%.

7. A targeted relaxation repair system for lithium-ion batteries after lithium plating, implementing the method of any one of claims 1-7, characterized in that... The system includes a data acquisition module, a lithium plating feature extraction module, a recoverable state determination module, a voltage relaxation completion calculation module, a target relaxation duration determination module, and a charge / discharge control module, wherein: The data acquisition module is used to collect battery voltage, current, and time data; The lithium plating feature extraction module is used to extract lithium plating-related voltage feature parameters; The recoverable state determination module is used to determine whether the battery is in a lithium plating recoverable state. The voltage relaxation completion calculation module is used to calculate the voltage relaxation completion. The target relaxation duration determination module is used to determine the target relaxation duration; The charge / discharge control module is used to control the battery to perform targeted relaxation repair operations.

8. The application of the targeted relaxation repair method for lithium battery after lithium plating as described in any one of claims 1-6 in lithium batteries, battery management systems, new energy vehicles, energy storage power stations, consumer electronic devices, or power tools.

9. The application according to claim 8, characterized in that... The lithium battery includes, but is not limited to, lithium-ion batteries, lithium metal batteries, and rechargeable batteries containing lithium electrode systems.

10. The application according to claim 8, characterized in that... The lithium batteries may take the form of pouch cells, cylindrical cells, prismatic cells, battery modules, or battery packs.

Images