Nondestructive lithium precipitation detection method and system for lithium battery

Abstract

The invention provides a nondestructive lithium precipitation detection method and system for a lithium battery, and relates to the technical field of lithium batteries, and the method comprises the steps: carrying out the constant-current and constant-voltage charging of the lithium battery, and collecting the electrical parameters of the lithium battery in the charging process; calculating a first lithium precipitation current generated by a lithium precipitation phenomenon in the constant current stage; calculating a second lithium precipitation current generated by the lithium precipitation phenomenon in the constant voltage stage; in combination with the environment temperature, the first lithium precipitation current and the second lithium precipitation current are substituted into a BV kinetic equation based on a Marcus-Hush kinetic model, and the effective lithium precipitation current density considering the environment temperature is obtained; calculating a charging duration deviation value between the SOC full-charge duration and the standard SOC full-charge duration of the lithium battery; and calculating the lithium precipitation mass based on the Faraday theorem according to the effective lithium precipitation current density and the charging duration deviation value. Automatic detection of lithium separation of the lithium battery is completed on line, the accuracy is high, the disassembly detection risk is avoided, the detection efficiency is improved, and the detection cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a non-destructive lithium deposition detection method and system for lithium batteries. Background Art

[0002] Lithium battery is a rechargeable battery that uses lithium metal or lithium ions as electrode materials. It is widely used in portable electronic devices, electric vehicles and energy storage devices due to its high energy density, long service life and light weight. Non-destructive lithium deposition detection is a detection method that does not destroy the battery structure. It detects lithium deposition by analyzing the electrochemical parameters of the battery during the charging and discharging process to avoid damage to the battery due to detection.

[0003] Non-destructive lithium deposition detection of lithium batteries can monitor the lithium deposition inside the battery in real time without destroying the battery structure, preventing battery performance degradation, capacity loss and potential safety risks. Through this detection method, the battery life can be improved, its reliability in electric vehicles and energy storage systems can be enhanced, and the safe operation of the equipment can be ensured.

[0004] However, the existing lithium battery lithium plating detection process requires manual disassembly of the lithium battery for contact detection, which will change the structure of the lithium battery during the detection process. The detection process is complicated and can easily damage the normal structure of the lithium battery, resulting in high detection risks, increased lithium plating detection costs, low practicality and inability to achieve online real-time detection. Summary of the invention

[0005] In order to solve the technical problems in the prior art that the lithium battery needs to be manually disassembled for contact testing during lithium deposition testing, the structure of the lithium battery will be changed during the testing process, the testing process is complicated and the normal structure of the lithium battery is easily damaged, resulting in high testing risks, increased lithium deposition testing costs, low practicality and inability to achieve online real-time testing, the present invention provides a non-destructive lithium deposition testing method and system for lithium batteries.

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

[0007] First aspect

[0008] An embodiment of the present invention provides a non-destructive lithium deposition detection method for a lithium battery, comprising:

[0009] S1: Perform constant current and constant voltage charging on the lithium battery, and collect the lithium battery electrical parameters during the charging process, wherein the lithium battery electrical parameters include the constant current stage charging voltage in the constant current charging stage, the constant voltage stage charging voltage in the constant voltage charging stage, the constant voltage stage current decay rate, the SOC full charge time, and the ambient temperature;

[0010] S2: Calculate the first lithium deposition current generated by lithium deposition in the constant current stage according to the charging voltage in the constant current stage;

[0011] S3: Calculating a second lithium deposition current generated by lithium deposition in the constant voltage stage according to the charging voltage in the constant voltage stage and the current decay rate in the constant voltage stage;

[0012] S4: In combination with the ambient temperature, the first lithium deposition current and the second lithium deposition current are substituted into the BV kinetic equation based on the Marcus-Hush kinetic model to obtain the effective lithium deposition current density considering the ambient temperature;

[0013] S5: Calculate the charging time deviation between the SOC full charge time and the standard SOC full charge time of the lithium battery;

[0014] S6: Calculate the lithium deposition mass based on the effective lithium deposition current density and the charging time deviation value based on Faraday's theorem;

[0015] S7: Output lithium deposition mass.

[0016] Second aspect

[0017] An embodiment of the present invention provides a non-destructive lithium deposition detection system for a lithium battery, comprising:

[0018] processor;

[0019] A memory having computer-readable instructions stored thereon, wherein when the computer-readable instructions are executed by the processor, the non-destructive lithium deposition detection method for a lithium battery as described in the first aspect is implemented.

[0020] The third aspect

[0021] An embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the non-destructive lithium deposition detection method of a lithium battery as described in the first aspect is implemented.

[0022] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0023] In the present invention, the electrical parameters of online charging of lithium batteries in a common constant current and constant voltage charging mode are easily collected, combined with the constant current stage charging voltage in the constant current charging stage, the constant voltage stage charging voltage in the constant voltage charging stage, the current decay rate in the constant voltage stage, the SOC full charge time and the ambient temperature, the influence of the actual ambient temperature on the charging is considered, and then the lithium deposition current generated by the lithium deposition phenomenon in the constant current stage and the second lithium deposition current generated by the lithium deposition phenomenon in the constant voltage stage are calculated based on the collected parameters, and then the obtained lithium deposition current is substituted into the BV kinetic equation based on the Marcus-Hush kinetic model, and the charge conversion in the lithium deposition process is fully considered. The kinetic mechanism of the shift and the influence of the ambient temperature on the reaction rate of lithium deposition can more accurately simulate and quantify the lithium deposition phenomenon, making the calculation of the lithium deposition current density more accurate, thereby improving the accuracy and reliability of the final lithium deposition quality detection, and then obtaining the effective lithium deposition current density that takes into account the kinetic characteristics of the electrochemical reaction and the influence of temperature, and then calculating the lithium deposition quality based on the effective lithium deposition current density and the charging time deviation value based on Faraday's theorem, taking into account the current change and charging time difference during the battery charging process, which can more accurately reflect the cumulative effect of the lithium deposition phenomenon, thereby improving the calculation accuracy of the lithium deposition quality and avoiding errors caused by a single parameter. The entire process data can be obtained online, and the acquisition method is simple. The real-time detection of the lithium deposition quality can be automatically completed without destroying the original structure of the lithium battery, greatly improving the detection efficiency and reducing the detection cost and detection risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 A schematic diagram of a flow chart of a non-destructive lithium deposition detection method for a lithium battery provided in an embodiment of the present invention;

[0026] Figure 2 A schematic structural diagram of a non-destructive lithium deposition detection system for a lithium battery provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0028] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0029] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0030] Reference Manual Attached Figure 1 , showing a schematic flow chart of a non-destructive lithium deposition detection method for a lithium battery provided in an embodiment of the present invention.

[0031] The embodiment of the present invention provides a non-destructive lithium deposition detection method for lithium batteries, which can be implemented by a non-destructive lithium deposition detection device for lithium batteries, and the non-destructive lithium deposition detection device for lithium batteries can be a terminal or a server. The processing flow of the non-destructive lithium deposition detection method for lithium batteries can include the following steps:

[0032] S1: Charge the lithium battery with constant current and constant voltage, and collect the electrical parameters of the lithium battery during the charging process.

[0033] Among them, the electrical parameters of the lithium battery include the constant current stage charging voltage in the constant current charging stage, the constant voltage stage charging voltage and the constant voltage stage current decay rate in the constant voltage charging stage, the SOC full charge time and the ambient temperature.

[0034] Among them, constant current and constant voltage charging is a commonly used charging method. The charging process is divided into two stages: the first is the constant current stage, in which the current remains unchanged and the voltage gradually increases. When the voltage reaches the set value, it enters the constant voltage stage, in which the voltage remains unchanged and the current gradually decreases. The constant current stage charging voltage is during the constant current charging process. As the battery is charged, the voltage gradually rises. The voltage at this time is the constant current stage charging voltage. The constant voltage stage charging voltage refers to the constant voltage stage in which the voltage remains unchanged at the set value until the current gradually decays to a very small value. In the constant voltage stage, as the charging proceeds, the current gradually decreases, and the rate of current decay is the current decay rate in the constant voltage stage. The SOC full charge time refers to the battery's state full charge time, that is, the time required from the start of charging to the battery being full.

[0035] It should be noted that by obtaining parameters such as constant current voltage, constant voltage, current decay rate and SOC full time, the electrochemical reaction characteristics and current change trends at different charging stages can be accurately reflected. These data can accurately capture the occurrence time, degree and dynamic changes of the lithium precipitation process, which is helpful to identify the lithium precipitation phenomenon at different charging stages and improve the comprehensiveness and accuracy of lithium precipitation detection.

[0036] In a possible implementation, S2 specifically includes:

[0037] S201: Calculate the charging overpotential in the constant current stage according to the charging voltage in the constant current stage:

[0038] η 恒流 =V 实际 -V 平衡

[0039] Among them, η 恒流 Indicates the charging overpotential during the constant current stage, V 实际 Indicates the charging voltage in the constant current stage, V 平衡 It indicates the equilibrium voltage of lithium battery without lithium deposition.

[0040] S202: Based on the charging voltage in the constant current stage, the first lithium deposition current is calculated using the Tafel equation:

[0041]

[0042] Where I1 represents the first lithium deposition current, e represents the natural constant, k0 represents the exchange current density when the overpotential is 0, b represents the Tafel slope related to the lithium battery electrode material, g represents the gas constant, T represents the absolute temperature inside the lithium battery, C represents the lithium battery pre-factor, E a Represents the activation energy of lithium battery reaction.

[0043] Among them, I0 specifically represents the exchange current density of the reaction rate of the exchange current density reaction lithium battery in the non-lithium state. The lithium battery pre-factor specifically represents the frequency of successful reaction without any energy barriers (such as activation energy). The activation energy of the lithium battery reaction specifically represents the minimum energy required for the lithium battery reaction, usually in joules / mole (J / mol). It represents the energy barrier that needs to be overcome for the reactants to be converted into products.

[0044] It should be noted that the Tafel equation describes the relationship between the current and the overpotential in the electrode reaction. By using the Tafel equation to calculate the first lithium deposition current, the relationship between the overpotential and the current change in the lithium deposition process can be accurately quantified, and combined with factors such as lithium battery material properties (such as Tafel slope) and temperature, it is ensured that the calculation of the lithium deposition current is more consistent with the actual kinetic process of the electrochemical reaction. This method can improve the detection accuracy of the lithium deposition phenomenon, especially in the constant current stage, it can effectively identify the early impact of lithium deposition on the charging current.

[0045] S2: Calculate the first lithium deposition current generated by the lithium deposition phenomenon in the constant current stage according to the charging voltage in the constant current stage.

[0046] Among them, the first lithium deposition current is the additional current caused by the lithium deposition phenomenon during the constant current charging stage. When lithium ions are precipitated as lithium metal on the surface of the negative electrode, it will cause a change in current. This part of the current is called the first lithium deposition current. By calculating the first lithium deposition current in the constant current stage, the current change during the lithium deposition process can be accurately quantified, providing basic data for the subsequent calculation of the lithium deposition quality. This method can capture the initial signs of lithium deposition in the early stages of charging, thereby more accurately evaluating the quality of lithium deposition and improving the accuracy of the final test results.

[0047] S3: Calculate the second lithium deposition current generated by the lithium deposition phenomenon in the constant voltage stage according to the charging voltage in the constant voltage stage and the current decay rate in the constant voltage stage.

[0048] Among them, the second lithium deposition current is the additional current caused by the lithium deposition phenomenon during the constant voltage stage. At this time, the battery voltage remains constant, but the current will gradually decay as the battery charge approaches saturation. The current change caused by the lithium deposition phenomenon is the second lithium deposition current. By calculating the second lithium deposition current in the constant voltage stage, it is possible to capture the current change of lithium deposition in the battery at the end of charging, especially to identify the lithium deposition phenomenon during the current decay process. In this way, the lithium deposition information throughout the charging cycle can be obtained more comprehensively, ensuring that the calculation of the lithium deposition quality is more accurate and complete, and improving the overall assessment of the battery health status.

[0049] In a possible implementation, S3 specifically includes:

[0050] S301: Calculate the charging overpotential in the constant voltage stage according to the charging voltage in the constant voltage stage:

[0051] η 恒压 =V' 实际 -V 平衡

[0052] Among them, η 恒压 Indicates the charging overpotential in the constant voltage stage, V' 实际 Indicates the charging voltage in the constant voltage stage, V 平衡 It indicates the equilibrium voltage of lithium battery without lithium deposition.

[0053] S302: Calculate the actual current after attenuation according to the current attenuation rate in the constant voltage stage:

[0054] I 衰减 =I 初始 ×(1-θ)

[0055] Among them, I 衰减 Indicates the actual current, I 初始 represents the initial current in the constant voltage stage, and θ represents the current decay rate in the constant voltage stage.

[0056] S303: Combine the charging overpotential and the actual current in the constant voltage stage and use the Tafel equation to calculate the second lithium deposition current:

[0057]

[0058] Wherein, I2 represents the second lithium deposition current.

[0059] It should be noted that by combining the charging overpotential and actual current in the constant voltage stage and using the Tafel equation to calculate the second lithium plating current, the dynamic change of current decay when the voltage is constant can be effectively considered, and the continuous impact of lithium plating on the current can be accurately reflected. It not only takes into account the current decay characteristics, but also quantifies the relationship between overpotential and current, which improves the detection accuracy of lithium plating in the later stage of charging, especially when the battery is close to full, and can more effectively evaluate the long-term impact of lithium plating on battery health.

[0060] S4: In combination with the ambient temperature, the first lithium deposition current and the second lithium deposition current are substituted into the BV kinetic equation based on the Marcus-Hush kinetic model to obtain the effective lithium deposition current density considering the ambient temperature.

[0061] Among them, the Marcus-Hush kinetic model is a classic theoretical model for describing electron transfer reactions, which is mainly used to explain the process of electron transfer from one molecule or ion to another in electrochemical reactions. The BV kinetic equation of the Marcus-Hush kinetic model is a model that describes the rate of electron transfer reactions. It is particularly suitable for electrochemical reactions. It combines factors such as electrode potential, overpotential, and reaction activation energy to explain the process of electron transfer from one reactant to another. The BV (Butler-Volmer) equation is a commonly used equation in electrochemistry to describe the relationship between current and potential. The Marcus-Hush model further introduces the concept of free energy of electron transfer reactions on the basis of the BV equation, taking into account the kinetic characteristics between molecules.

[0062] It should be noted that by substituting the first and second lithium deposition currents into the BV kinetic equation and combining the current density calculated with influencing factors such as ambient temperature, the intensity of the lithium deposition phenomenon under actual working conditions can be more truly reflected. First of all, in this process, the complexity of ambient temperature, reaction kinetics and electrochemical processes is taken into account to obtain a lithium deposition current density that is more in line with the actual situation. This can not only improve the accuracy of the calculation, but also better reflect the dynamic changes of the lithium deposition process under different conditions, which is helpful to improve the accuracy of lithium deposition quality assessment. In addition, the calculated effective lithium deposition current density can more comprehensively reflect the impact of different charging stages and ambient temperatures on the lithium deposition process, ensure that lithium deposition detection is more accurate, and reduce errors, thereby improving the effectiveness and reliability of battery health status monitoring.

[0063] In a possible implementation, the effective lithium deposition current density is calculated as follows:

[0064]

[0065] Where α represents the charge transfer coefficient, represents the effective lithium deposition current density, J eff represents the intermediate variable, T env Indicates the ambient temperature, It represents the activation free energy required for electron transfer in lithium batteries calculated based on the Marcus-Hush kinetic model, and F represents the Faraday constant.

[0066] It should be noted that by calculating the effective lithium deposition current density based on the Marcus-Hush kinetic model, the kinetic factors in the charge transfer process, such as the charge transfer coefficient, activation free energy, and temperature, can be comprehensively considered. This model accurately describes the electron transfer behavior in the lithium deposition process, especially the introduction of the influence of temperature and kinetic barriers, making the current density calculation more in line with the actual electrochemical environment. Compared with the simple current-potential relationship model, this calculation method can more comprehensively reflect the occurrence of lithium deposition under different conditions, improving the accuracy of identifying the lithium deposition phenomenon and the evaluation effect of the battery health status.

[0067] In a possible implementation, the activation free energy is calculated as follows:

[0068]

[0069] Among them, λ represents the reorganization energy required for the polarization of lithium battery solvent, η in Indicates the overpotential during charging, η during constant current charging in =η 恒流 , during constant voltage charging, η in =η 恒压 .

[0070] Among them, activation free energy is the minimum energy barrier that needs to be overcome to transform from reactants to products in a chemical reaction. In electrochemical reactions, it represents the energy required by the reactants during electron transfer in order to be able to cross the energy barrier and react. Activation free energy is an important factor in determining the reaction rate. The higher the energy, the slower the reaction, and vice versa. For the lithium deposition phenomenon in lithium batteries, activation free energy is used to describe the energy barrier that needs to be overcome when lithium ions undergo deposition reactions on the electrode surface. By calculating the activation free energy, the ease of lithium deposition and the reaction rate can be predicted, which helps to better understand the behavior of batteries under different charging conditions.

[0071] By combining the activation free energy calculation formula with the reorganization energy of lithium battery solvent polarization and the overpotential of the charging process, the energy barriers that need to be overcome in the electron transfer process can be more accurately reflected. This method takes into account the actual kinetic characteristics of the electrode reaction and combines the different characteristics of the charging stage to make the calculation of activation free energy more accurate, especially for describing the energy requirements of complex electrochemical reactions, and can better predict lithium precipitation behavior and its possibility of occurrence.

[0072] S5: Calculate the charging time deviation between the SOC full charge time and the standard SOC full charge time of the lithium battery.

[0073] It should be noted that by calculating the charging time deviation between the SOC full charge time and the standard SOC full charge time, the abnormal charging time change caused by lithium plating during the charging process of the battery can be quantified. This deviation value can be used as an indirect indicator of the lithium plating state of the battery, which helps to identify the decrease in charging efficiency and the deterioration of the battery health state caused by lithium plating, thereby providing an effective reference value to detect lithium plating and improve the accuracy and comprehensiveness of the overall lithium plating detection.

[0074] In a possible implementation manner, the charging time deviation value is specifically:

[0075] Δt=t actual -t standard

[0076] Among them, Δt represents the charging time deviation value, t actual Indicates the SOC full time, t standard Indicates the standard SOC full charge time.

[0077] It should be noted that by calculating the charging time deviation between the SOC full charge time and the standard full charge time, the abnormal situation in the charging process can be quantified. This calculation method can directly reflect the problem of reduced charging efficiency due to lithium deposition or battery aging, and provides a simple and effective indicator to evaluate the battery health status, thereby helping to timely detect the degradation of battery performance or potential failures.

[0078] S6: Calculate the lithium deposition mass based on the effective lithium deposition current density and the charging time deviation value based on Faraday's law.

[0079] Among them, Faraday's law, or Faraday's law of electrolysis, describes the relationship between current and generated substances in electrochemical reactions. It describes the principle that in the electrolysis process, after a period of current, the amount of substance generated on the electrode is proportional to the amount of electricity. By combining the effective lithium plating current density and the charging time deviation value, and using Faraday's law to calculate the lithium plating mass, the lithium plating phenomenon can be quantified into a specific mass value. This method can not only directly reflect the impact of lithium plating on battery capacity, but also correlate complex electrochemical processes with actual mass changes, thereby providing more accurate results for lithium plating detection, which helps to evaluate the health and life of the battery.

[0080] In a possible implementation, the lithium deposition mass is calculated as follows:

[0081]

[0082] Among them, m Li represents the mass of lithium precipitated, A represents the effective area of ​​lithium battery electrode, M Li represents the molar mass of lithium element, n=1 represents the number of electron transfers, and Δt represents the deviation value of charging time.

[0083] It should be noted that by combining the effective lithium deposition current density, charging time deviation, electrode effective area and molar mass of lithium element to calculate the lithium deposition mass, the influence of lithium deposition under different charging conditions can be more comprehensively reflected. This method accurately considers multiple factors such as current, time and electrode surface area, and can quantify the actual influence of lithium deposition on battery capacity and performance, thereby improving the accuracy of lithium deposition mass calculation and providing a scientific basis for battery performance evaluation.

[0084] S7: Output lithium deposition mass.

[0085] In a possible implementation manner, after S7, the method further includes:

[0086] When the lithium deposition mass is greater than the preset lithium deposition mass, an early warning is issued.

[0087] It should be noted that by issuing an early warning when the lithium deposition mass exceeds the preset value, the user can be promptly reminded that the battery has obvious lithium deposition, which helps to take preventive measures in advance to avoid rapid degradation of battery performance or safety hazards. This mechanism ensures that the battery is within the safe range during operation, prolongs the battery life and improves the reliability of the overall system.

[0088] In actual use, by collecting key electrical parameters of the lithium battery charging stage, including the voltage, current decay rate and SOC full charge time in the constant current stage and constant voltage stage, the current generated by lithium precipitation in the constant current and constant voltage stages is calculated respectively. These currents are then substituted into the BV kinetic equation of the Marcus-Hush kinetic model, and the effective lithium precipitation current density is calculated in combination with the ambient temperature. The deviation between the SOC full charge time and the standard time is calculated, and the lithium precipitation quality is finally calculated based on Faraday's theorem combined with the effective lithium precipitation current density and the charging time deviation. This process combines the electrochemical characteristics and environmental factors of different charging stages, and can comprehensively and accurately quantify the lithium precipitation phenomenon, thereby improving the accuracy of lithium precipitation detection and the reliability of battery health status assessment.

[0089] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0090] In the present invention, the electrical parameters of online charging of lithium batteries in a common constant current and constant voltage charging mode are easily collected, combined with the constant current stage charging voltage in the constant current charging stage, the constant voltage stage charging voltage in the constant voltage charging stage, the constant voltage stage current decay rate, the SOC full charge time and the ambient temperature, and the influence of the actual ambient temperature on charging is considered. Then, based on the collected parameters, the lithium deposition current generated by the lithium deposition phenomenon in the constant current stage and the second lithium deposition current generated by the lithium deposition phenomenon in the constant voltage stage are calculated. Then, the obtained lithium deposition current is substituted into the BV kinetic equation based on the Marcus-Hush kinetic model, and the kinetic mechanism of charge transfer in the lithium deposition process and the influence of ambient temperature on the lithium deposition reaction rate are fully considered, so that more accurate simulation and quantification can be achieved. The lithium deposition phenomenon makes the calculation of lithium deposition current density more accurate, thereby improving the accuracy and reliability of the final lithium deposition quality detection. After that, the effective lithium deposition current density considering the kinetic characteristics of the electrochemical reaction and the influence of temperature is obtained. Then, according to the effective lithium deposition current density and the charging time deviation value, the lithium deposition quality is calculated based on Faraday's theorem. Considering the current change and charging time difference during battery charging, the cumulative effect of the lithium deposition phenomenon can be more accurately reflected, thereby improving the calculation accuracy of the lithium deposition quality and avoiding errors caused by a single parameter. The data of the entire process can be obtained online, and the acquisition method is simple. The real-time detection of lithium deposition quality can be automatically completed without destroying the original structure of the lithium battery, which greatly improves the detection efficiency and reduces the detection cost and detection risk.

[0091] Reference Manual Attached Figure 2 , showing a structural schematic diagram of a non-destructive lithium deposition detection system for a lithium battery provided by the present invention.

[0092] The present invention further provides a non-destructive lithium deposition detection system 20 for a lithium battery, which is applied to the above-mentioned non-destructive lithium deposition detection method for a lithium battery, comprising:

[0093] Processor 201.

[0094] The memory 202 stores computer-readable instructions. When the computer-readable instructions are executed by the processor 201, the non-destructive lithium deposition detection method of the lithium battery in the method embodiment is implemented.

[0095] The non-destructive lithium deposition detection system 20 for lithium batteries provided by the present invention can execute the above-mentioned non-destructive lithium deposition detection method for lithium batteries and achieve the same or similar technical effects. To avoid repetition, the present invention will not go into details.

[0096] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0097] In the present invention, the electrical parameters of online charging of lithium batteries in a common constant current and constant voltage charging mode are easily collected, combined with the constant current stage charging voltage in the constant current charging stage, the constant voltage stage charging voltage in the constant voltage charging stage, the constant voltage stage current decay rate, the SOC full charge time and the ambient temperature, and the influence of the actual ambient temperature on charging is considered. Then, based on the collected parameters, the lithium deposition current generated by the lithium deposition phenomenon in the constant current stage and the second lithium deposition current generated by the lithium deposition phenomenon in the constant voltage stage are calculated. Then, the obtained lithium deposition current is substituted into the BV kinetic equation based on the Marcus-Hush kinetic model, and the kinetic mechanism of charge transfer in the lithium deposition process and the influence of ambient temperature on the lithium deposition reaction rate are fully considered, so that lithium deposition can be simulated and quantified more accurately. The phenomenon makes the calculation of lithium deposition current density more accurate, thereby improving the accuracy and reliability of the final lithium deposition quality detection, and then obtains the effective lithium deposition current density which takes into account the kinetic characteristics of the electrochemical reaction and the temperature influence, and then calculates the lithium deposition quality based on the effective lithium deposition current density and the charging time deviation value based on Faraday's theorem, taking into account the current change and the charging time difference during the battery charging process, which can more accurately reflect the cumulative effect of the lithium deposition phenomenon, thereby improving the calculation accuracy of the lithium deposition quality and avoiding the error caused by a single parameter. The data of the entire process can be obtained online, and the acquisition method is simple. The real-time detection of the lithium deposition quality can be automatically completed without destroying the original structure of the lithium battery, which greatly improves the detection efficiency and reduces the detection cost and detection risk.

[0098] It should be understood that the processor in the embodiment of the present invention may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0099] It should also be understood that the memory in the embodiments of the present invention may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM bus random access memory (DR RAM).

[0100] The above embodiments can be implemented in whole or in part by software, hardware (such as circuits), firmware or any other combination. When implemented by software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a tape), an optical medium (for example, a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0101] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

[0102] In the present invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can be represented by: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0103] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned stages does not mean the order of execution. The execution order of each stage should be determined by its function and internal logic, and should not constitute any limitation on the implementation stage of the embodiments of the present invention.

[0104] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0105] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working stages of the equipment, devices and units described above can refer to the corresponding stages in the aforementioned method embodiments and will not be repeated here.

[0106] In the several embodiments provided by the present invention, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0107] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0108] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0109] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, etc., various media that can store program codes.

[0110] An embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the non-destructive lithium deposition detection method for a lithium battery as described in the method embodiment is implemented.

[0111] A computer-readable storage medium provided by the present invention can implement the steps and effects of the non-destructive lithium deposition detection method for lithium batteries of the above method embodiment. To avoid repetition, the present invention will not go into details.

[0112] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0113] In the present invention, the electrical parameters of online charging of lithium batteries in a common constant current and constant voltage charging mode are easily collected, combined with the constant current stage charging voltage in the constant current charging stage, the constant voltage stage charging voltage in the constant voltage charging stage, the constant voltage stage current decay rate, the SOC full charge time and the ambient temperature, and the influence of the actual ambient temperature on charging is considered. Then, based on the collected parameters, the lithium deposition current generated by the lithium deposition phenomenon in the constant current stage and the second lithium deposition current generated by the lithium deposition phenomenon in the constant voltage stage are calculated. Then, the obtained lithium deposition current is substituted into the BV kinetic equation based on the Marcus-Hush kinetic model, and the kinetic mechanism of charge transfer in the lithium deposition process and the influence of ambient temperature on the lithium deposition reaction rate are fully considered, so that lithium deposition can be simulated and quantified more accurately. The phenomenon makes the calculation of lithium deposition current density more accurate, thereby improving the accuracy and reliability of the final lithium deposition quality detection, and then obtains the effective lithium deposition current density which takes into account the kinetic characteristics of the electrochemical reaction and the temperature influence, and then calculates the lithium deposition quality based on the effective lithium deposition current density and the charging time deviation value based on Faraday's theorem, taking into account the current change and the charging time difference during the battery charging process, which can more accurately reflect the cumulative effect of the lithium deposition phenomenon, thereby improving the calculation accuracy of the lithium deposition quality and avoiding the error caused by a single parameter. The data of the entire process can be obtained online, and the acquisition method is simple. The real-time detection of the lithium deposition quality can be automatically completed without destroying the original structure of the lithium battery, which greatly improves the detection efficiency and reduces the detection cost and detection risk.

[0114] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0115] There are a few points to note:

[0116] (1) The drawings of the embodiments of the present invention only relate to the structures related to the embodiments of the present invention, and other structures may refer to the general design.

[0117] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present invention, the thickness of the layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, the element may be "directly" "on" or "under" the other element or there may be intermediate elements.

[0118] (3) In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to obtain new embodiments.

[0119] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A non-destructive lithium deposition detection method for lithium batteries, characterized in that: include: S1: Perform constant current and constant voltage charging on the lithium battery, and collect the electrical parameters of the lithium battery during the charging process, wherein the electrical parameters of the lithium battery include the constant current stage charging voltage in the constant current charging stage, the constant voltage stage charging voltage in the constant voltage charging stage, the constant voltage stage current decay rate, the SOC full charge time, and the ambient temperature; S2: Calculating a first lithium deposition current generated by lithium deposition in the constant current stage according to the charging voltage in the constant current stage; S3: calculating a second lithium deposition current generated by the lithium deposition phenomenon in the constant voltage stage according to the charging voltage in the constant voltage stage and the current attenuation rate in the constant voltage stage; S4: In combination with the ambient temperature, substituting the first lithium deposition current and the second lithium deposition current into a BV kinetic equation based on a Marcus-Hush kinetic model to obtain an effective lithium deposition current density considering the ambient temperature; S5: Calculating a charging time deviation between the SOC full charge time and a standard SOC full charge time of the lithium battery; S6: Calculating the lithium deposition mass based on the effective lithium deposition current density and the charging time deviation value based on Faraday's theorem; S7: Output the lithium deposition mass.

2. The non-destructive lithium deposition detection method of a lithium battery according to claim 1, characterized in that: The S2 specifically includes: S201: Calculate the constant current stage charging overpotential according to the constant current stage charging voltage: η 恒流 =V 实际 -V 平衡 Among them, η 恒流 Indicates the charging overpotential during the constant current stage, V 实际 Indicates the charging voltage in the constant current stage, V 平衡 Indicates the equilibrium voltage of the lithium battery without lithium deposition; S202: Based on the charging voltage in the constant current stage, the first lithium deposition current is calculated using the Tafel equation: Where I1 represents the first lithium deposition current, e represents the natural constant, k0 represents the exchange current density when the overpotential is 0, b represents the Tafel slope related to the lithium battery electrode material, g represents the gas constant, T represents the absolute temperature inside the lithium battery, C represents the lithium battery pre-factor, E a Represents the activation energy of lithium battery reaction.

3. The non-destructive lithium deposition detection method of a lithium battery according to claim 2, characterized in that: The S3 specifically includes: S301: Calculate the constant voltage stage charging overpotential according to the constant voltage stage charging voltage: η 恒压 =V' 实际 -V 平衡 Among them, η 恒压 Indicates the charging overpotential in the constant voltage stage, V' 实际 Indicates the charging voltage in the constant voltage stage, V 平衡 Indicates the equilibrium voltage of the lithium battery without lithium deposition; S302: Calculate the actual current after attenuation according to the current attenuation rate in the constant voltage stage: I 衰减 =I 初始 ×(1-θ) Among them, I 衰减 Indicates the actual current, I 初始 represents the initial current in the constant voltage stage, and θ represents the current decay rate in the constant voltage stage; S303: Calculate the second lithium deposition current by using the Tafel equation based on the charging overpotential in the constant voltage stage and the actual current: Wherein, I2 represents the second lithium deposition current.

4. The non-destructive lithium deposition detection method of a lithium battery according to claim 3, characterized in that: The calculation method of the effective lithium precipitation current density is specifically as follows: Where α represents the charge transfer coefficient, represents the effective lithium deposition current density, J eff represents the intermediate variable, T env Indicates the ambient temperature, It represents the activation free energy required for electron transfer in lithium batteries calculated based on the Marcus-Hush kinetic model, and F represents the Faraday constant.

5. The non-destructive lithium deposition detection method of a lithium battery according to claim 4, characterized in that: The activation free energy is calculated as follows: Among them, λ represents the reorganization energy required for the polarization of lithium battery solvent, η in Indicates the overpotential during charging, η during constant current charging in =η 恒流 , during constant voltage charging, η in =η 恒压 .

6. The non-destructive lithium deposition detection method of a lithium battery according to claim 1, characterized in that: The charging time deviation value is specifically: Δt=t actual -t standard Among them, Δt represents the charging time deviation value, t actual Indicates the SOC full time, t standard Indicates the standard SOC full charge time.

7. The non-destructive lithium deposition detection method of a lithium battery according to claim 4, characterized in that: The calculation method of the lithium precipitation mass is specifically as follows: Among them, m Li represents the mass of lithium precipitated, A represents the effective area of ​​lithium battery electrode, M Li represents the molar mass of lithium element, n=1 represents the number of electron transfers, and Δt represents the deviation value of charging time.

8. The non-destructive lithium deposition detection method of a lithium battery according to claim 7, characterized in that: After S7, the method further includes: When the lithium deposition mass is greater than the preset lithium deposition mass, an early warning is issued.

9. A non-destructive lithium deposition detection system for lithium batteries, characterized in that: include: processor; A memory having computer-readable instructions stored thereon, wherein when the computer-readable instructions are executed by the processor, the non-destructive lithium deposition detection method for a lithium battery as claimed in any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, a non-destructive lithium deposition detection method for a lithium battery as described in any one of claims 1 to 8 is implemented.

Images