A lithium battery adaptive charging method and system

Abstract

The application provides a lithium battery adaptive charging method and system, and relates to the technical field of lithium battery charging. The method comprises the following steps: establishing a state of charge equation describing the change of the lithium battery electric quantity with the charging current; calculating the positive electrode current density and the negative electrode current density of the lithium battery under the charging current; combining the positive electrode current density and the negative electrode current density, and determining the internal charging voltage of the lithium battery under the charging current by using a BV kinetics equation; determining the SEI layer overpotential related to the SEI layer generation rate; calculating the SEI layer generation current related to the charging current according to the SEI layer overpotential; establishing a relationship function of the SEI layer generation current and the capacity loss of the lithium battery; establishing a charging current linear attenuation equation; establishing a charging current optimization equation to solve the expected charging current; and charging the lithium battery. While not reducing the charging efficiency, the excessive generation of the SEI layer in the charging process is reduced, and the service life of the lithium battery is increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery charging, in particular to a lithium battery adaptive charging method and system. BACKGROUND

[0002] Lithium batteries are rechargeable batteries widely used in electronic devices, electric vehicles, energy storage systems, and other fields. Lithium batteries are known for their high energy density, light weight, and long life, making them one of the most commonly used battery types in modern electronic products. The SEI (Solid Electrolyte Interphase) layer is a solid-state electrolyte interface layer that forms on the surface of the negative electrode of a lithium battery, especially when the negative electrode material comes into contact with the electrolyte. The SEI layer is formed during the first charging process. The SEI layer is crucial to the life of a lithium battery, as it has a significant impact on the battery's cycle performance, capacity retention, and battery life. A stable SEI layer can protect the negative electrode material, reduce electrolyte decomposition and lithium ion loss, thereby extending the battery life. However, if the SEI layer is unstable or overgrown, it will consume active lithium ions, leading to capacity loss and shortening the battery life.

[0003] Lithium batteries exhibit different electrochemical reaction rates and side reactions under different usage conditions, such as SEI layer formation and electrolyte decomposition. These reactions can cause battery capacity to decay, internal resistance to increase, and battery life to shorten. Adaptive charging technology can adjust the charging current and voltage in real time according to the actual operating state of the battery, avoiding overcharging, overheating, and other phenomena, reducing stress and side reactions on battery materials, and maintaining an efficient and safe charging process. By precisely controlling the charging process, adaptive charging not only extends the life of the battery, but also improves charging efficiency, meeting the demand for fast and safe charging in modern devices, especially in scenarios such as electric vehicles that require long life and high efficiency. In addition, adaptive charging can reduce energy loss and optimize charging time, achieving the best charging performance while ensuring battery safety.

[0004] However, existing lithium battery charging methods often use traditional constant current and constant voltage charging methods, which can improve charging speed but do not consider the overgrowth of the SEI layer caused by this constant charging method, which consumes too many lithium ions and rapidly reduces the life of the lithium battery under multiple charging cycles. SUMMARY

[0005] In order to solve the technical problem that the existing lithium battery charging method often adopts the traditional constant current and constant voltage charging method, although the charging speed can be improved, but in this process, the excessive generation of SEI layer caused by the constant charging method is not considered, too many lithium ions are consumed, and the service life of the lithium battery is rapidly reduced after multiple charging cycles, the application provides a lithium battery adaptive charging method and system.

[0006] The technical scheme provided by the embodiment of the application is as follows:

[0007] The first aspect

[0008] The lithium battery adaptive charging method provided by the embodiment of the application comprises:

[0009] S1: establishing a state of charge equation describing the change of the lithium battery capacity with the charging current;

[0010] S2: calculating the positive electrode current density and the negative electrode current density of the lithium battery under the charging current;

[0011] S3: combining the positive electrode current density and the negative electrode current density, and determining the internal charging voltage of the lithium battery under the charging current by using a BV kinetics equation describing the charge transfer process;

[0012] S4: determining the SEI layer overpotential related to the SEI layer generation rate;

[0013] S5: calculating the SEI layer generation current related to the charging current according to the SEI layer overpotential;

[0014] S6: establishing a relationship function between the SEI layer generation current and the capacity loss of the lithium battery;

[0015] S7: establishing a charging current linear attenuation equation;

[0016] S8: combining the charging current attenuation equation, establishing a charging current optimization equation with the minimum capacity loss as the target, with the lithium battery capacity reaching the expected lithium battery capacity, the internal charging voltage being lower than the expected charging voltage, and the charging time being less than the expected charging time as the constraint, and solving the charging current optimization equation to obtain the expected charging current;

[0017] S9: charging the lithium battery with the expected charging current.

[0018] The second aspect

[0019] The lithium battery adaptive charging system provided by the embodiment of the application comprises:

[0020] A processor;

[0021] A memory having computer readable instructions stored thereon, the computer readable instructions, when executed by the processor, implement the lithium battery adaptive charging method according to the first aspect.

[0022] Third aspect

[0023] The embodiment of the present application provides a computer readable storage medium, and a computer program is stored on the computer readable storage medium. The program is executed by a processor to implement the lithium battery adaptive charging method according to the first aspect.

[0024] The technical scheme provided by the embodiment of the present application has at least the following beneficial effects:

[0025] In the present application, a state of charge equation describing the change of the lithium battery capacity with the charging current is established, and the BV kinetic equation describing the charge transfer process is used to determine the internal charging voltage of the lithium battery under the charging current, and then the SEI layer overpotential and the SEI layer generation current closely related to the SEI layer generation rate are determined, the generation process of the SEI layer is dataized, and the capacity loss of the lithium battery is solved, so that the generation of the SEI layer is effectively inhibited by controlling the charging current, and a charging current linear decay equation for quickly solving is established to control the charging current, increase the response speed of the charging current control, and then combine the capacity loss minimization as the target, the lithium battery capacity reaching the expected lithium battery capacity, the internal charging voltage being lower than the expected charging voltage, and the charging time being less than the expected charging time as the constraints of the charging current optimization equation, the charging current is quickly adjusted to the expected charging current without overcharging and exceeding the traditional constant current constant voltage charging time, the excessive generation of the SEI layer is effectively avoided, the capacity loss of the lithium battery in the charging process is reduced under the condition of ensuring the charging efficiency, and the lithium battery charging safety and the lithium battery life are improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 A flowchart of a lithium battery adaptive charging method provided by the embodiment of the present application is shown in the figure.

[0028] Figure 2 A structure diagram of a lithium battery adaptive charging system provided by the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0029] The technical solutions in the present application will be described below with reference to the drawings.

[0030] In the embodiments of the present application, the words such as "example", "for example" are used to represent an example, illustration, or description. Any embodiment or design scheme described as "example" in the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the word "example" is intended to present the concept in a specific manner. In addition, in the embodiments of the present application, the meaning expressed by "and / or" can be both, or can be one of the two.

[0031] In order to make the technical problems, technical solutions and advantages to be solved by the present application more clear, the following will be described in detail in combination with the drawings and specific embodiments.

[0032] Referring to the drawings attached Figure 1 , a flowchart of a lithium battery adaptive charging method provided by an embodiment of the present application is shown.

[0033] An embodiment of the present application provides a lithium battery adaptive charging method, which can be implemented by a lithium battery adaptive charging device, which can be a terminal or a server. The processing flow of the lithium battery adaptive charging method can include the following steps:

[0034] S1: Establish a state of charge equation describing the change of the lithium battery electric quantity with the charging current.

[0035] Wherein, the charging current is the current flowing into the battery during the charging process, which represents the amount of electric charge passing through the battery per unit time. The size of the charging current determines the charging speed. The greater the current, the faster the charging speed. However, excessive current can cause damage to the battery. The electric quantity of the lithium battery and the state of charge (SOC) have a close relationship. The electric quantity represents the remaining electric energy in the battery, while the state of charge is a percentage form describing the proportion of the remaining electric quantity of the battery to the total capacity of the battery. By establishing the state of charge equation, the remaining electric quantity of the lithium battery can be monitored in real time, and it can be determined whether the battery is fully charged to avoid overcharging or overdischarging, thereby protecting the battery, prolonging the service life, and optimizing the charging process.

[0036] In a possible implementation, the state of charge equation is specifically:

[0037]

[0038] Wherein, SOC and SOC 0 respectively represent the state of charge and the initial state of charge, t and t 0 respectively represent the current time and the charging start time, I represents the charging current, represents the maximum charge capacity of the lithium battery.

[0039] wherein the maximum charge capacity of the lithium battery refers to the maximum amount of electric charge that the lithium battery can store and release under specific conditions.

[0040] It should be noted that establishing this state of charge equation accurately calculates the state of charge of the battery through integration of the charging current, allowing real-time monitoring of the remaining battery capacity and ensuring the accuracy of the charging process, avoiding overcharging or undercharging, and improving the safety and service life of the battery. At the same time, this equation can help optimize the charging strategy, making the charging process more efficient.

[0041] S2: Calculate the anode current density and cathode current density of the lithium battery under the charging current.

[0042] wherein the anode current density represents the amount of electric current flowing through the anode of the battery per unit area per unit time, reflecting the amount of charge carried by the anode during charging. The cathode current density represents the amount of electric current flowing through the cathode of the battery per unit area per unit time, reflecting the rate of charge transfer of the cathode. Current density is a key factor affecting charging efficiency and battery degradation, and in order to optimize the charging current, the reaction current density of the anode and cathode needs to be understood first. By calculating the current density of the anode and cathode, it can help optimize the distribution of charging current, avoid excessive current concentration on a certain pole, prevent damage to battery materials, improve charging efficiency and prolong battery life.

[0043] In one possible implementation, the anode current density and cathode current density are respectively:

[0044]

[0045] wherein, and represent the anode current density and cathode current density respectively, F represents the Faraday constant, and represent the specific surface area and thickness of the lithium battery cathode respectively, and represent the specific surface area and thickness of the lithium battery anode respectively.

[0046] wherein the specific surface area refers to the surface area per unit volume or unit mass of the lithium battery electrode material. The thickness refers to the physical thickness of the lithium battery anode or cathode material. By calculating the current density of the anode and cathode through the specific surface area and thickness, the distribution of current on the electrode can be more accurately described, helping to optimize the charging current.

[0047] S3: Combine the anode current density and cathode current density, and use the BV kinetics equation describing the charge transfer process to determine the internal charging voltage of the lithium battery under the charging current.

[0048] The Butler-Volmer kinetic equation (BV) describes the relationship between electrode reaction rate and electrode potential. It states that the current density at an electrode depends on the magnitude of the overpotential, and the kinetics of an electrochemical reaction are determined by the difference between the forward and reverse reaction rates. This equation is widely used to describe charge transfer processes in electrochemical systems such as batteries and fuel cells. The internal charge voltage refers to the actual voltage within the battery (primarily between the positive and negative electrodes) during charging. It includes the voltage generated during the electrochemical reaction, the internal resistance of each material, and the polarization voltage. Unlike the externally measured voltage, the internal charge voltage reflects the true internal operating state of the battery. By combining the positive and negative electrode current densities with the BV kinetic equation, accurate calculation of the internal charge voltage of a lithium battery can help optimize the charging process, avoid battery damage caused by excessive voltage, and improve charging safety and efficiency. Specifically, it constrains the battery voltage during charging to prevent overcharge damage.

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

[0050] S301: Establish BV kinetic equation:

[0051]

[0052] in, and Respectively k The electrode reaction current density and k The electrode standard reaction current density is the exchange current density, sinh represents the hyperbolic sine function, represents the gas constant, T represents absolute temperature, 、 and Respectively k The solid phase potential, liquid phase potential and open circuit potential of the electrode, where k represents an indicator variable, k = pos or neg ,when k = pos When it indicates the positive electrode of lithium battery, k = neg When indicates the negative pole of lithium battery.

[0053] in, It is the actual reaction current density on the electrode. It indicates the amount of current occurring per unit time on the electrode per unit area during the actual electrochemical reaction, that is, the reaction rate. is the reaction current density under standard state, also known as exchange current density, which represents the current density when the forward reaction and reverse reaction rates on the electrode are equal without external potential difference (i.e. the electrode is in open circuit state). Among them, the solid phase potential refers to the potential of the solid conductor in the positive or negative material of the lithium battery, the liquid phase potential refers to the potential in the electrolyte, that is, the potential of lithium ion migration in the electrolyte, and the open circuit potential refers to the electrode potential of the battery when no current passes through (i.e. the open circuit state of the battery). By establishing the BV kinetic equation, the current density change in the positive and negative electrode reaction process of the lithium battery can be accurately described, the electrochemical reaction kinetics is revealed, the charging strategy is optimized, and the charging and discharging performance of the battery is improved.

[0054] S302: Invert the BV kinetic equation to solve the positive and negative solid phase potentials of the lithium battery:

[0055]

[0056] wherein, represents the inverse function of the hyperbolic sine function, and respectively represent the positive electrode current density and the positive electrode standard exchange current density.

[0057] It should be noted that by inverting the BV kinetic equation to solve the solid phase potential of the electrode, the potential distribution inside the battery can be obtained, and the actual working state of the battery during charging can be more accurately understood.

[0058] S303: Calculate the internal charging voltage according to the positive and negative solid phase potentials:

[0059]

[0060] wherein, represents the internal charging voltage, and respectively represent the positive and negative solid phase potentials.

[0061] It can be understood that the internal charging voltage can be calculated according to the solid phase potentials of the positive and negative electrodes, which can more comprehensively understand the internal voltage change of the battery, avoid overcharging of the battery at high voltage, and thus protect the safety of the battery.

[0062] S304: Substitute the positive and negative current densities into the internal charging voltage to obtain the internal charging voltage under the charging current:

[0063]

[0064] wherein, represents the open circuit voltage of the lithium battery, R represents the internal resistance of the lithium battery, and Istand and Istand represent the standard current of the positive electrode and the standard current of the negative electrode of the lithium battery, respectively.

[0065] Specifically, steps S301-S304 describe the current density change in the electrode reaction using the BV kinetics equation, solve the electrode solid phase potential after reversing the equation, and further calculate the internal charging voltage. By substituting the positive and negative electrode current density, the internal charging voltage model is further optimized, so as to accurately reflect the voltage change of the lithium battery under different charging conditions. This process aims to ensure the stability and safety of the battery during charging, while optimizing the charging speed and efficiency, and reducing the damage of the battery caused by overcharging.

[0066] S4: Determine the SEI layer overpotential related to the SEI layer generation rate.

[0067] Wherein, the SEI layer is a key factor affecting the aging of the battery, and the generated SEI layer will consume lithium, leading to loss of battery capacity. The higher the overpotential, the faster the SEI layer is generated. In order to prolong the life of the battery, the most important goal is to minimize the capacity loss caused by the generation of SEI layer. SEI layer overpotential refers to the difference between the electrode potential and its equilibrium potential when the negative electrode of the lithium battery contacts with the electrolyte and forms a solid electrolyte interface layer. Overpotential is the additional energy required for electrochemical reaction, which usually leads to the occurrence of side reactions, such as electrolyte decomposition and SEI layer generation.

[0068] It should be noted that by determining the overpotential related to the SEI layer generation rate, the side reactions of the battery during charging can be effectively monitored and controlled, the excessive generation of SEI layer can be reduced, the excessive consumption of lithium ions can be avoided, the battery life can be prolonged, and the charging efficiency and safety can be improved.

[0069] In one possible implementation, the SEI layer overpotential is specifically:

[0070]

[0071] Wherein, represents the SEI layer side reaction current density, represents the SEI layer side reaction exchange current density, represents the SEI layer overpotential, n represents the number of electron transfer, represents the SEI layer impedance, represents the SEI layer potential, represents the electrochemical transfer coefficient, and exp represents the exponential function, represents the open circuit potential of the negative electrode of the lithium battery, represents the Faraday current density of the negative electrode of the lithium battery, represents the overpotential of the lithium battery negative electrode, represents the exchange current density of the lithium battery negative electrode.

[0072] wherein SEI layer side reaction current density is the current density generated by the SEI layer (solid-state electrolyte interface), and the electrochemical transfer coefficient determines how the activation energy barrier of the reaction changes with the change of the electrode potential, which indicates that the reaction process is relatively symmetrical in the charge transfer reaction of the anode and the cathode, and when the electrode potential changes, the energy barrier (activation energy barrier) required for the reaction will also change, if the electrode potential increases, it may reduce the energy required for the reaction, making the reaction more likely to occur, and vice versa. The electrochemical transfer coefficient determines the speed and amplitude of this change. By calculating the SEI layer overpotential, the occurrence of side reactions can be accurately predicted, the generation conditions of the SEI layer can be optimized, and the consumption of lithium ions caused by excessive generation can be avoided, thereby reducing the loss of battery capacity, prolonging the life of the battery, and maintaining the stability of the battery performance, effectively improving the charging efficiency and safety.

[0073] S5: According to the SEI layer overpotential, calculate the SEI layer generation current related to the charging current.

[0074] wherein the SEI layer generation current refers to the current generated by the side reaction on the negative electrode surface to generate the solid-state electrolyte interface layer during the charging process of the lithium battery, this current is related to the generation rate of the SEI layer, and excessive SEI layer generation current means that the side reaction on the negative electrode surface is relatively strong, resulting in more consumption of lithium ions and electrolyte, affecting the battery capacity. By calculating the SEI layer generation current related to the charging current, the strength of the side reaction can be accurately evaluated, helping to optimize the charging current, reduce excessive consumption of lithium ions, prevent excessive generation of the SEI layer, thereby prolonging the life of the battery and improving the safety and efficiency of the charging process.

[0075] In one possible implementation, the SEI layer generation current is specifically:

[0076]

[0077] wherein, represents the SEI layer generation current, represents the SEI layer side reaction exchange current, represents the reference potential of the SEI layer side reaction.

[0078] It should be noted that by calculating the SEI layer generation current in this way, the dynamic process of the SEI layer side reaction can be accurately reflected, considering factors such as potential difference and temperature, so as to better control the generation rate of the SEI layer, reduce the capacity loss caused by the side reaction of the battery, prolong the life of the battery, and optimize the charging efficiency and safety.

[0079] S6: Establish a relationship function between SEI layer generation current and capacity loss of lithium battery.

[0080] wherein the capacity loss of lithium battery refers to the phenomenon that the amount of charge that the battery can store and release gradually decreases as the number of uses increases. By establishing a relationship function between SEI layer generation current and capacity loss of lithium battery, the capacity loss mechanism caused by side reactions can be clearly determined, helping to accurately predict the degree of battery aging, optimize charging strategies, reduce capacity decay, thereby prolonging the service life of the battery and maintaining performance stability.

[0081] In one possible implementation, the relationship function is specifically:

[0082]

[0083] wherein, represents the capacity loss.

[0084] It should be noted that by establishing a relationship function between SEI layer generation current and capacity loss in this way, the battery capacity loss caused by side reactions can be directly quantified, the battery decay rate can be accurately predicted, which helps to optimize the charging strategy, reduce the battery capacity loss, thereby prolonging the service life of the battery and improving the stability and reliability of the battery performance.

[0085] S7: Establish a linear decay equation for charging current.

[0086] It should be noted that the linear decay strategy can maintain a high charging current in the early stage of charging to speed up the charging speed, and gradually reduce the charging current when the battery is close to full to avoid excessive stress and side reactions on the battery caused by high current, reducing damage to the battery. By establishing a linear decay equation for charging current, efficient and safe balance can be achieved during the charging process, ensuring the speed of charging and preventing overheating and side reactions caused by high current when close to full, protecting the service life of the battery and improving the safety of charging.

[0087] In one possible implementation, the linear decay equation for charging current is specifically:

[0088]

[0089] wherein, I 1 represents the initial charging current, represents the decay rate of charging current.

[0090] It should be noted that establishing a linear decay equation for charging current can gradually reduce the charging current during the charging process, avoid long-time charging of the battery under high current, reduce the occurrence of battery heating and side reactions, thereby reducing damage to the battery, prolonging the service life of the battery, and improving the safety and stability of the charging process.

[0091] S8: combine the charging current decay equation, establish a charging current optimization equation with the minimum capacity loss as the target, with the lithium battery power reaching the expected lithium battery power, the internal charging voltage being lower than the expected charging voltage, and the charging time being less than the expected charging time as constraints, and solve the charging current optimization equation to obtain the expected charging current.

[0092] It should be noted that by constructing the charging current optimization equation for minimizing capacity loss, the capacity loss can be effectively reduced while ensuring the safety and charging efficiency of the battery, avoiding the impact of overcharging or long-time charging on the battery life, thereby improving the overall service life and performance of the battery.

[0093] In one possible implementation, the charging current optimization equation is specifically:

[0094]

[0095] where min represents taking the minimum value, represents the constraint condition, represents the state of charge at the maximum charging time represents the charging time of the lithium battery under constant current and constant voltage charging, i.e. the expected charging time, represents the maximum allowed charging voltage of the lithium battery, i.e. the expected charging voltage, represents the maximum allowed charging current of the lithium battery, represents the maximum state of charge, represents the expected charging current. It should be noted that through this charging current optimization equation, the capacity loss due to the generation of the SEI layer can be minimized while ensuring that the lithium battery reaches the target state of charge within the expected time. At the same time, the equation constrains the battery current, voltage and charging time, ensuring a safe and efficient charging process. The optimization equation also considers the linear decay of the charging current, making the charging process more stable, reducing the impact on the battery life, and improving the charging efficiency and service life of the battery. The expected charging current can be obtained by simple arithmetic calculation of the formula.

[0096] S9: charge the lithium battery with the expected charging current.

[0097]

[0098] ​In practical application, the lithium battery adaptive charging process first monitors the battery power in real time through the state of charge equation to ensure the accuracy of the charging process. Then the current density of the positive and negative electrodes is calculated, the internal charging voltage during charging is determined by combining the BV kinetics equation, and the SEI layer overpotential calculation related to the SEI layer generation current is determined. Then, the relationship function between the SEI layer generation current and the capacity loss is established, the capacity loss of the battery is calculated, and the charging current is optimized by combining the linear decay equation. Finally, the minimum capacity loss is taken as the target to ensure the efficiency and safety of the battery charging. By optimizing the charging current and controlling the generation of the SEI layer, the battery aging caused by excessive current density is avoided. The linear decay charging strategy can balance the charging speed and battery life to ensure the safe completion of the battery charging in a high efficiency.

[0099] The technical scheme provided by the embodiment of the present application has at least the following beneficial effects:

[0100] In the present application, a state of charge equation describing the change of lithium battery power with charging current is established, and the BV kinetics equation describing the charge transfer process is used to determine the internal charging voltage of the lithium battery under the charging current. Then the SEI layer overpotential and SEI layer generation current closely related to the SEI layer generation rate are determined, the SEI layer generation process is dataized, and the lithium battery capacity loss is solved to effectively suppress the generation by controlling the charging current. A charging current linear decay equation is established to quickly solve the charging current, increase the response speed of the charging current regulation, and then combine the charging current optimization equation with the minimum capacity loss as the target, the lithium battery power reaching the expected lithium battery power, the internal charging voltage being lower than the expected charging voltage, and the charging time being less than the expected charging time as constraints. The charging current is quickly adjusted to the expected charging current without overcharging and exceeding the traditional constant current constant voltage charging time, effectively avoiding the excessive generation of the SEI layer, reducing the lithium battery capacity loss during the charging process without losing the charging efficiency, and improving the lithium battery charging safety and lithium battery life.

[0101] Reference is made to the accompanying drawings Figure 2 , which shows a structural schematic diagram of a lithium battery adaptive charging system provided by the present application.

[0102] The present application also provides a lithium battery adaptive charging system 20 applied to the above-mentioned lithium battery adaptive charging method, which comprises:

[0103] A processor 201.

[0104] A memory 202, the memory 202 stores computer readable instructions, and the computer readable instructions are executed by the processor 201 to realize the lithium battery adaptive charging method of the method embodiment.

[0105] The lithium battery adaptive charging system 20 provided by the present application can execute the lithium battery adaptive charging method described above and achieve the same or similar technical effects, and the present application will not be described again to avoid repetition.

[0106] The technical scheme provided by the embodiment of the present application brings at least the following beneficial effects:

[0107] In the present application, a state of charge equation describing the change of the lithium battery capacity with the charging current is established, and the BV kinetics equation describing the charge transfer process is used to determine the internal charging voltage of the lithium battery under the charging current, and then the SEI layer overpotential and SEI layer generation current closely related to the SEI layer generation rate are determined, the SEI layer generation process is dataized, and the lithium battery capacity loss is solved, so as to effectively inhibit the generation by controlling the charging current, and a charging current linear decay equation is established for convenient and fast solution to regulate the charging current, increase the response speed of the charging current regulation, and then combine the capacity loss minimization as the target, the lithium battery capacity reaching the expected lithium battery capacity, the internal charging voltage being lower than the expected charging voltage, and the charging time being less than the expected charging time as the constraints of the charging current optimization equation, the charging current is quickly adjusted to the expected charging current without overcharging and exceeding the traditional constant current constant voltage charging time, the excessive generation of the SEI layer is effectively avoided, the lithium battery capacity loss in the charging process is reduced under the condition of ensuring the charging efficiency without loss, and the lithium battery charging safety and the lithium battery life are improved.

[0108] It should be understood that the processor in the embodiment of the present application can be a central processing unit (CPU), and the processor can also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), ready-to-program gate arrays (FPGAs), or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0109] It should also be understood that the memory in the embodiments of the present application can be volatile or nonvolatile memory, or can include both volatile and nonvolatile memory. Nonvolatile memory can be read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically EPROM (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), which is used as external cache. By way of example, and not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0110] The above-described embodiments can be implemented in whole or in part by software, hardware (such as a circuit), firmware, or any combination thereof. When implemented in software, the above-described embodiments can be implemented 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 processes or functions described in the embodiments of the present application are wholly or partially generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center through a wired (such as infrared, wireless, microwave, etc.) manner. 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, data center, etc. containing one or more available medium collections. The available medium can be a magnetic medium (such as a floppy disk, a hard disk, a magnetic tape), an optical medium (such as a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state disk.

[0111] It should be understood that the term "and / or" herein merely describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. In addition, the character " / " herein generally represents that the associated objects before and after it are in an "or" relationship, but it can also represent an "and / or" relationship, which can be understood according to the context before and after it.

[0112] In the present application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or the like means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can represent a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0113] It should be understood that in various embodiments of the present application, the size of the sequence number of the above-described processes does not mean the order of execution, and the execution order of the processes should be determined according to their functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0114] Those skilled in the art can clearly understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0115] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working processes of the devices, apparatuses and units described above can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0116] In several embodiments provided by the present application, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, for example, multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0117] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0118] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit.

[0119] If the functions are realized in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application or the parts of the present application that essentially contribute to the prior art or the parts of the technical solutions can be embodied in the form of a software product stored in a storage medium, including a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in various embodiments of the present application. The aforementioned storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0120] The embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the program is executed by a processor to realize the adaptive charging method of the lithium battery.

[0121] The computer readable storage medium provided by the present application can realize the steps and effects of the adaptive charging method of the lithium battery in the above method embodiments, and the present application will not be repeated here to avoid repetition.

[0122] The technical solutions provided by the embodiment of the present application have at least the following beneficial effects:

[0123] In the present application, a state of charge equation describing the change of the lithium battery capacity with the charging current is established, and a BV kinetic equation describing the charge transfer process is used to determine the internal charging voltage of the lithium battery under the charging current, and then the SEI layer overpotential and the SEI layer generation current closely related to the SEI layer generation rate are determined, the generation process of the SEI layer is dataized, and the capacity loss of the lithium battery is solved, so as to effectively inhibit the generation by controlling the charging current, and a charging current linear decay equation is established for convenient and fast solving to regulate the charging current, increase the response speed of the charging current regulation, and then combine the capacity loss minimization as the target, the lithium battery capacity reaching the expected lithium battery capacity, the internal charging voltage being lower than the expected charging voltage, and the charging time being less than the expected charging time as the constraints of the charging current optimization equation, the charging current is quickly adjusted to the expected charging current without overcharging and exceeding the traditional constant current constant voltage charging time, the excessive generation of the SEI layer is effectively avoided, the capacity loss of the lithium battery in the charging process is reduced under the condition of ensuring the charging efficiency without loss, and the lithium battery charging safety and the lithium battery life are improved.

[0124] The above merely describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0125] The following points need to be explained:

[0126] (1) The attached drawings of the embodiments of the present application only involve the structures involved in the embodiments of the present application, and other structures can be referred to the general design.

[0127] (2) In order to be clear, the thickness of the layer or region is enlarged or reduced in the drawings used for describing the embodiments of the present application, that is, the drawings are not drawn according to the actual proportion. It can be understood that when the elements such as layer, film, region or substrate are referred to as being located "on" or "under" another element, the element can be "directly" located "on" or "under" another element or there can be intermediate elements.

[0128] (3) In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0129] The above merely describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A lithium battery adaptive charging method, characterized in that: include: S1: Establish the state of charge equation that describes the change of lithium battery capacity with charging current; S2: Calculating the positive electrode current density and the negative electrode current density of the lithium battery under the charging current; S3: Determine the internal charging voltage of the lithium battery at the charging current using a BV kinetic equation describing a charge transfer process, based on the positive electrode current density and the negative electrode current density; S4: determining the SEI layer overpotential related to the SEI layer formation rate; S5: Calculating the SEI layer generated current related to the charging current according to the SEI layer overpotential; S6: establishing a relationship function between the SEI layer generation current and the capacity loss of the lithium battery; S7: Establishing the charging current linear decay equation; S8: In combination with the charging current attenuation equation, establishing a charging current optimization equation with the goal of minimizing the capacity loss and with the constraints that the lithium battery power reaches the expected lithium battery power, the internal charging voltage is lower than the expected charging voltage, and the charging time is shorter than the expected charging time, and solving the charging current optimization equation to obtain the expected charging current; S9: charging the lithium battery with the desired charging current; Wherein, the S3 specifically includes: S301: Establish the BV kinetic equation: ； in, and Respectively k The electrode reaction current density and k The electrode standard reaction current density is the exchange current density, sinh represents the hyperbolic sine function, represents the gas constant, T represents absolute temperature, 、 and Respectively k The solid phase potential, liquid phase potential and open circuit potential of the electrode, where k represents an indicator variable, k = POS or neg ,when k = POS When it indicates the positive electrode of lithium battery, k = neg When indicates the negative electrode of lithium battery; S302: Invert the BV kinetic equation to solve the positive electrode solid phase potential and negative electrode solid phase potential of the lithium battery: ； in, represents the inverse function of the hyperbolic sine function, and represent the positive electrode current density and the positive electrode standard exchange current density respectively; S303: Calculate the internal charging voltage based on the positive electrode solid phase potential and the negative electrode solid phase potential: ； in, Indicates the internal charging voltage, and represent the positive electrode solid phase potential and the negative electrode solid phase potential respectively; S304: Substitute the positive electrode current density and the negative electrode current density into the internal charging voltage to obtain the internal charging voltage under the charging current: ； in, Indicates the open circuit voltage of lithium battery, R Indicates the internal resistance of the lithium battery, and Respectively represent the positive standard current and negative standard current of the lithium battery; The SEI layer overpotential is specifically: ； in, represents the SEI layer side reaction current density, represents the SEI layer side reaction exchange current density, represents the SEI layer overpotential, n represents the number of electron transfers, represents the SEI layer impedance, represents the SEI layer potential, represents the electrochemical transfer coefficient, exp represents the exponential function, Indicates the open circuit potential of the negative electrode of the lithium battery, represents the Faraday current density of the negative electrode of the lithium battery, Indicates the negative electrode overpotential of lithium battery. It represents the exchange current density of the negative electrode of lithium battery.

2. The lithium battery adaptive charging method according to claim 1, characterized in that: The state of charge equation is specifically: ； in, SOC and SOC 0 represents the state of charge and the initial state of charge, t and t 0 represents the current time and the charging start time, I Indicates the charging current, Indicates the maximum charge capacity of the lithium battery.

3. The lithium battery adaptive charging method according to claim 1, characterized in that: The positive electrode current density and the negative electrode current density are respectively: ； in, and are the positive electrode current density and the negative electrode current density, respectively. F represents the Faraday constant, and Respectively represent the specific surface area and thickness of the negative electrode of the lithium battery, and Respectively represent the specific surface area and thickness of the lithium battery positive electrode.

4. The lithium battery adaptive charging method according to claim 1, characterized in that: The SEI layer generates a current specifically as follows: ； in, represents the current generated by the SEI layer, represents the SEI layer side reaction exchange current, Represents the reference potential of side reactions in the SEI layer.

5. The lithium battery adaptive charging method according to claim 1, characterized in that: The relationship function is specifically: ； in, Indicates capacity loss.

6. The lithium battery adaptive charging method according to claim 1, characterized in that: The linear attenuation equation of the charging current is specifically: ； in, I 1 represents the initial charging current, Indicates the charging current decay rate.

7. The lithium battery adaptive charging method according to claim 6, characterized in that: The charging current optimization equation is specifically: ； Among them, min means taking the minimum value, represents the constraints, Indicates the maximum charging time The state of charge when Indicates the charging time of lithium battery under constant current and constant voltage charging, that is, the expected charging time. Indicates the maximum allowable charging voltage of the lithium battery, that is, the expected charging voltage. Indicates the maximum allowable charging current of the lithium battery. Indicates the maximum state of charge, Indicates the expected charging current.

8. A lithium battery adaptive charging system, 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 lithium battery adaptive charging method according to any one of claims 1 to 7 is implemented.

Images