Lithium battery self-adaptive charging method and system

Abstract

The invention provides a lithium battery self-adaptive charging method and system, and relates to the technical field of lithium battery charging, and the method comprises the steps: building a state-of-charge equation describing the change of the electric quantity of a lithium battery along with the charging current; calculating the positive electrode current density and the negative electrode current density of the lithium battery under the charging current; determining the internal charging voltage of the lithium battery under the charging current by using a BV kinetic equation in combination with the positive electrode current density and the negative electrode current density; determining an SEI layer overpotential associated with the SEI layer generation rate; calculating SEI layer generation current related to the charging current according to the SEI layer overpotential; establishing a relation function between 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, and solving an expected charging current; and charging the lithium battery. And while the charging efficiency is not reduced, the excessive generation of an SEI layer in the charging process is reduced, and the service life of the lithium battery is prolonged.

Description

Technical Field

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

[0002] Lithium battery is a rechargeable battery widely used in electronic equipment, electric vehicles, energy storage systems and other fields. Lithium battery is known for its high energy density, light weight and long life. It is one of the most commonly used battery types in modern electronic products. SEI (Solid Electrolyte Interphase) layer is a solid electrolyte interface layer, which is generated on the surface of the negative electrode of lithium battery, especially when the negative electrode material is in contact with the electrolyte, the SEI layer will be formed during the first charge. The SEI layer is crucial to the life of lithium battery, and it has a great influence on the battery's cycle performance, capacity retention rate 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, but if the SEI layer is unstable or over-generated, it will consume active lithium ions, resulting in capacity loss and shortening the battery life.

[0003] Lithium batteries will exhibit different electrochemical reaction speeds and side reactions under different conditions of use, such as the formation of SEI layer and electrolyte decomposition. These reactions will cause battery capacity decay, increase internal resistance, and shorten battery life. Adaptive charging technology can adjust the charging current and voltage in real time according to the actual operating status of the battery, avoid overcharging, overheating and other phenomena, reduce stress and side reactions on battery materials, and maintain an efficient and safe charging process. By precisely controlling the charging process, adaptive charging can not only extend the service life of the battery, but also improve charging efficiency, meet the needs of modern equipment for fast and safe charging, especially in scenarios such as electric vehicles that require long life and high efficiency. In addition, adaptive charging can reduce energy loss, optimize charging time, and achieve optimal charging performance while ensuring battery safety.

[0004] However, the existing lithium battery charging method often adopts the traditional constant current and constant voltage charging method. Although it can increase the charging speed, it does not take into account that this constant charging method will cause excessive generation of SEI layer and consume too many lithium ions, which will rapidly reduce the life of lithium batteries under multiple charging cycles. Summary of the invention

[0005] In order to solve the problem that the lithium battery charging method in the prior art often adopts the traditional constant current and constant voltage charging method, although it can improve the charging speed, it does not take into account that this constant charging method will cause excessive generation of SEI layer, consume too many lithium ions, and rapidly reduce the life of the lithium battery under multiple charging cycles. The present invention provides a lithium battery adaptive charging method and system.

[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 lithium battery adaptive charging method, comprising:

[0009] S1: Establish the state of charge equation that describes the change of lithium battery power with charging current;

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

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

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

[0013] S5: Calculate the SEI layer generated current related to the charging current according to the SEI layer overpotential;

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

[0015] S7: Establishing the charging current linear decay equation;

[0016] S8: Combined with the charging current attenuation equation, a charging current optimization equation is established with the goal of minimizing capacity loss, 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 less than the expected charging time, and the charging current optimization equation is solved to obtain the expected charging current;

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

[0018] Second aspect

[0019] An embodiment of the present invention provides a lithium battery adaptive charging system, comprising:

[0020] processor;

[0021] 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 as described in the first aspect is implemented.

[0022] The third aspect

[0023] 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 lithium battery adaptive charging method as described in the first aspect is implemented.

[0024] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0025] In the present invention, a state of charge equation describing the change of lithium battery power with 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 SEI layer generation current closely related to the SEI layer generation rate are determined, the SEI layer generation process is digitized, and then the lithium battery capacity loss is solved, so as to effectively inhibit its generation by controlling the charging current, and a charging current linear attenuation equation that is convenient and quickly solved is established to regulate the charging current, increase the charging current regulation response speed, and then combine the charging current optimization equation with the goal of minimizing capacity loss, 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, the charging current is quickly adjusted to the expected charging current without overcharging and not exceeding the traditional constant current and constant voltage charging time, effectively avoiding excessive generation of the SEI layer, reducing the lithium battery capacity loss during the charging process while ensuring that the charging efficiency is not lost, and improving the charging safety and life of the lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. 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.

[0027] Figure 1 A schematic diagram of a flow chart of a lithium battery adaptive charging method provided by an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the structure of a lithium battery adaptive charging system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0030] 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.

[0031] 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.

[0032] Reference Manual Attached Figure 1 , showing a schematic flow chart of a lithium battery adaptive charging method provided in an embodiment of the present invention.

[0033] The embodiment of the present invention provides a lithium battery adaptive charging method, which can be implemented by a lithium battery adaptive charging device, and the lithium battery adaptive charging device 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 that describes how the charge level of a lithium battery changes with charging current.

[0035] Among them, the charging current is the current that flows into the battery during the charging process. It represents the amount of charge that passes through the battery per unit time. The size of the charging current determines the charging speed. The larger the current, the faster the charging speed, but too much current will damage the battery. There is a close relationship between the power of a lithium battery and the state of charge (SOC). The power represents the remaining electrical energy in the battery, while the state of charge describes the proportion of the remaining power of the battery to the total capacity of the battery in the form of a percentage. By establishing the state of charge equation, the remaining power of the lithium battery can be monitored in real time, and it can be determined whether the battery is fully charged, avoiding overcharging or over-discharging, thereby protecting the battery, extending its service life, and optimizing the charging process.

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

[0037]

[0038] Among them, SOC and SOC 0 represent the state of charge and initial state of charge, t and t 0 They represent the current time and the time when charging starts, I represents the charging current, Q max Indicates the maximum charge capacity of a lithium battery.

[0039] Among them, the maximum charge capacity of a lithium battery refers to the maximum amount of charge that a lithium battery can store and release under specific conditions.

[0040] It should be noted that the establishment of this state of charge equation accurately calculates the battery state of charge by integrating the charging current, so that the remaining power of the battery can be monitored in real time, 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 and make the charging process more efficient.

[0041] S2: Calculate the positive electrode current density and negative electrode current density of the lithium battery under the charging current.

[0042] Among them, the positive electrode current density refers to the amount of current flowing through the positive electrode of the battery per unit area per unit time, which reflects the amount of charge carried by the positive electrode during the charging process. The negative electrode current density refers to the amount of current flowing through the negative electrode of the battery per unit area per unit time, which reflects the charge transfer rate of the negative electrode. Current density is a key factor affecting charging efficiency and battery degradation. In order to optimize the charging current, you first need to understand the reaction current density of the positive and negative electrodes. By calculating the current density of the positive and negative electrodes, it can help optimize the charging current distribution, avoid excessive current concentration at one electrode, prevent damage to battery materials, improve charging efficiency and extend battery life.

[0043] In one possible implementation, the positive electrode current density and the negative electrode current density are respectively:

[0044]

[0045] Among them, j neg and j pos They represent the positive electrode current density and the negative electrode current density respectively, F represents the Faraday constant, and a neg and l neg Respectively represent the specific surface area and thickness of the negative electrode of the lithium battery, a pos and l pos Respectively represent the specific surface area and thickness of the positive electrode of the lithium battery.

[0046] Among them, specific surface area refers to the surface area per unit volume or unit mass of lithium battery electrode materials. Thickness refers to the physical thickness of the positive or negative electrode materials of lithium batteries. Calculating the current density of the positive and negative electrodes by specific surface area and thickness can more accurately describe the distribution of current on the electrodes and help optimize the charging current.

[0047] S3: Combine the positive electrode current density and the negative electrode current density, and use the BV kinetic equation that describes the charge transfer process to determine the internal charging voltage of the lithium battery under the charging current.

[0048] Among them, the BV kinetic equation (Butler-Volmer kinetic equation) is an equation that describes the relationship between the electrode reaction rate and the electrode potential. It shows that the current density on the electrode depends on the size of the overpotential, and the kinetic process of the electrochemical reaction is determined by the difference between the forward and reverse reaction rates. This equation is widely used to describe the charge transfer process of electrochemical systems such as batteries and fuel cells. The internal charging voltage refers to the actual voltage of the internal parts of the battery (mainly between the positive and negative electrodes) during the charging process. It includes the voltage generated during the electrochemical reaction, the internal resistance of each material, and the polarization voltage. Unlike the voltage measured externally, the internal charging voltage can reflect the true working state inside the battery. By combining the positive and negative electrode current densities and the BV kinetic equation, the internal charging voltage of the lithium battery can be accurately calculated, which helps to optimize the charging process, avoid battery damage caused by excessive voltage, and improve charging safety and efficiency, that is, constrain the lithium battery voltage during the charging process to avoid overcharge damage to the battery.

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

[0050] S301: Establish the BV kinetic equation:

[0051]

[0052] Among them, j k and j k,0 They represent the k-electrode reaction current density and the k-electrode standard reaction current density, i.e., the exchange current density. sinh represents the hyperbolic sine function. R g represents the gas constant, T represents the absolute temperature, and They represent the solid phase potential, liquid phase potential and open circuit potential of the k electrode respectively, where k represents an indicator variable, k=pos or neg, when k=pos it represents the positive electrode of the lithium battery, and when k=neg it represents the negative electrode of the lithium battery.

[0053] Among them, j k It is the actual reaction current density on the electrode, which 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. k,0It is the reaction current density under standard conditions, also known as the exchange current density. It indicates the current density when the rates of the forward reaction and reverse reaction on the electrode are equal when there is no external potential difference (i.e. the electrode is in an open circuit state). Among them, the solid phase potential refers to the potential of the solid conductor in the positive or negative electrode material of the lithium battery, the liquid phase potential refers to the potential in the electrolyte, that is, the potential of lithium ions when migrating in the electrolyte, and the open circuit potential refers to the electrode potential of the battery when no current passes through (i.e. the battery is in an open circuit state). By establishing the BV kinetic equation, the current density changes during the positive and negative electrode reactions of lithium batteries can be accurately described, revealing the kinetics of electrochemical reactions, helping to optimize charging strategies and improve the battery's charge and discharge performance.

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

[0055]

[0056] Among them, sinh -1 represents the inverse function of the hyperbolic sine function, J pos and J 0,pos represent the positive electrode current density and the positive electrode standard exchange current density, respectively.

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

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

[0059]

[0060] Among them, V cell Indicates the internal charging voltage, and represent the positive electrode solid phase potential and the negative electrode solid phase potential respectively.

[0061] It can be understood that calculating the internal charging voltage based on the solid phase potential of the positive and negative electrodes can provide a more comprehensive understanding of the internal voltage changes of the battery, avoid overcharging the battery under high voltage, and thus protect the battery safety.

[0062] 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:

[0063]

[0064] Among them, U 0 represents the open circuit voltage of the lithium battery, R represents the internal resistance of the lithium battery, I0,a and I 0,c They represent the positive standard current and negative standard current of the lithium battery respectively.

[0065] Specifically, steps S301-S304 use the BV kinetic equation to describe the change in current density in the electrode reaction, invert the equation to solve the electrode solid phase potential, and then calculate the internal charging voltage. By substituting the positive and negative electrode current densities, the internal charging voltage model is further optimized, so that the voltage change of the lithium battery under different charging conditions can be accurately reflected. This process is designed to ensure the stability and safety of the battery during charging, while optimizing the charging speed and efficiency and reducing battery damage caused by overcharging.

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

[0067] Among them, the SEI layer is a key factor affecting battery aging. The generated SEI layer consumes lithium, resulting in battery capacity loss. The higher the overpotential, the faster the SEI layer is generated. In order to extend the life of the battery, the most important goal is to minimize the capacity loss caused by the generation of the SEI layer. The SEI layer overpotential refers to the difference between the electrode potential and its equilibrium potential when a chemical reaction occurs when the negative electrode of a lithium battery contacts the electrolyte to form a solid electrolyte interface layer. The overpotential is the additional energy that the electrochemical reaction needs to overcome, which usually leads to the occurrence of side reactions, such as electrolyte decomposition and the generation of the SEI layer.

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

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

[0070] j SEI =-i 0,SEI a neg exp[αnη SEI ]

[0071] η SEI =φ s -φ l -R film j tot -U SEI

[0072] η SEI =U n -U SEI +η n

[0073]

[0074] Among them, j SEI represents the SEI layer side reaction current density, i 0,SEI represents the SEI layer side reaction exchange current density, η SEI represents the SEI layer overpotential, n represents the number of electron transfers, R film represents the SEI layer impedance, U SEI represents the SEI layer potential, α=0.5 represents the electrochemical transfer coefficient, exp represents the exponential function, U n Indicates the open circuit potential of the negative electrode of the lithium battery, j n Represents the Faraday current density of the negative electrode of the lithium battery, η n Indicates the negative electrode overpotential of lithium battery. Represents the exchange current density of the negative electrode of the lithium battery.

[0075] Among them, the SEI layer side reaction current density is the current density generated by the SEI layer (solid electrolyte interface). The electrochemical transfer coefficient determines how the activation energy barrier of the reaction changes with the change of the electrode potential. α = 0.5 indicates that the reaction process is relatively symmetrical in the charge transfer reaction of the anode and cathode. When the electrode potential changes, the energy barrier (activation energy barrier) required for the reaction will also change. If the electrode potential increases, the energy required for the reaction may be reduced, making the reaction easier to occur, and vice versa. The electrochemical transfer coefficient determines the speed and magnitude of this change. By calculating the SEI layer overpotential, the occurrence of side reactions can be accurately predicted, the formation conditions of the SEI layer can be optimized, and the consumption of lithium ions caused by excessive formation can be avoided, thereby reducing battery capacity loss, extending battery life, and maintaining stable battery performance, effectively improving charging efficiency and safety.

[0076] S5: Calculate the SEI layer generated current related to the charging current according to the SEI layer overpotential.

[0077] Among them, SEI layer generation current refers to the current generated when a solid electrolyte interface layer is generated on the negative electrode surface due to side reactions during the charging process of a lithium battery. This current is related to the generation rate of the SEI layer. Excessive SEI layer generation current means that the side reactions on the negative electrode surface are relatively strong, resulting in more lithium ions and electrolyte being consumed, affecting the battery capacity. By calculating the SEI layer generation current related to the charging current, the intensity of the side reactions can be accurately evaluated, helping to optimize the charging current, reduce excessive lithium ion consumption, and prevent excessive generation of the SEI layer, thereby extending the battery life and improving the safety and efficiency of the charging process.

[0078] In a possible implementation manner, the SEI layer generates a current specifically as follows:

[0079]

[0080] Among them, I Sei represents the current generated by the SEI layer, I 0,Sei represents the SEI layer side reaction exchange current, U Sei ref =0.4 represents the reference potential of the side reaction of the SEI layer.

[0081] It should be noted that calculating the SEI layer generation current in this way can accurately reflect the dynamic process of the SEI layer side reaction, taking into account factors such as potential difference and temperature, so as to better control the SEI layer generation rate, reduce the capacity loss caused by battery side reactions, extend battery life, and optimize charging efficiency and safety.

[0082] S6: Establish the relationship function between the SEI layer generation current and the capacity loss of the lithium battery.

[0083] Among them, the capacity loss of lithium batteries refers to the phenomenon that the amount of charge that the battery can store and release gradually decreases as the number of times it is used increases. By establishing a relationship function between the SEI layer generation current and the lithium battery capacity loss, the capacity loss mechanism caused by side reactions can be clarified, which helps to accurately predict the degree of battery aging, optimize charging strategies, reduce capacity attenuation, and thus extend battery life and maintain stable performance.

[0084] In a possible implementation, the relationship function is specifically:

[0085]

[0086] Among them, Q loss Indicates capacity loss.

[0087] It should be noted that by establishing the relationship function between the SEI layer generated current and capacity loss in this way, the battery capacity loss caused by side reactions can be directly quantified, and the battery decay rate can be accurately predicted, which helps to optimize the charging strategy, reduce battery capacity loss, thereby extending the battery life and improving the stability and reliability of battery performance.

[0088] S7: Establish the charging current linear decay equation.

[0089] 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, so as to avoid excessive stress and side reactions of high current on the battery and reduce damage to the battery. By establishing a linear decay equation for the charging current, a balance between efficiency and safety can be achieved during the charging process, which not only ensures the charging speed, but also prevents overheating and side reactions caused by high current when the battery is close to full, protects the battery life and improves charging safety.

[0090] In a possible implementation manner, the charging current linear decay equation is specifically:

[0091] I=I 1 -I 2 t

[0092] Among them, I 1 Indicates the initial charging current, I 2 Indicates the charging current decay rate.

[0093] It should be noted that establishing a linear attenuation equation for charging current can gradually reduce the charging current during the charging process, avoid charging the battery for a long time at high current, reduce battery heating and the occurrence of side reactions, thereby reducing damage to the battery, extending battery life, and improving the safety and stability of the charging process.

[0094] S8: Combined with the charging current attenuation equation, a charging current optimization equation is established with the goal of minimizing capacity loss, 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 less than the expected charging time, and the charging current optimization equation is solved to obtain the expected charging current.

[0095] It should be noted that by constructing a charging current optimization equation that minimizes capacity loss, it is possible to effectively reduce capacity loss while ensuring battery safety and charging efficiency, avoid the impact of overcharging or charging for too long on battery life, and thus improve the overall service life and performance of the battery.

[0096] In a possible implementation, the charging current optimization equation is specifically:

[0097] Q loss

[0098] St

[0099] I des =I 1 -I 2 t

[0100] SOC(t max )=1

[0101] I des ”I max

[0102] t max ”t CC-CV

[0103]

[0104] Among them, min means taking the minimum value, St means the constraint condition, SOC(t max) indicates the maximum charging time t max The state of charge at t CC-CV Indicates the charging time of lithium battery under constant current and constant voltage charging, that is, the expected charging time, V max Indicates the maximum allowable charging voltage of the lithium battery, that is, the expected charging voltage, I max Indicates the maximum allowable charging current of the lithium battery, SOC max Indicates the maximum state of charge, I des Indicates the expected charging current.

[0105] It should be noted that through this charging current optimization equation, the capacity loss caused by the formation 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 to ensure that the charging process is safe and efficient. The optimization equation also takes into account the linear attenuation of the charging current, making the charging process smoother, reducing the impact on 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.

[0106] S9: Charge the lithium battery with the desired charging current.

[0107] In actual application, this 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, and the internal charging voltage during charging is determined in combination with the BV kinetic equation, and the SEI layer generation current related to the charging current is calculated through the SEI layer overpotential. Next, 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 in combination with the linear decay equation, and finally the minimum capacity loss is taken as the goal to ensure the efficiency and safety of battery charging. By optimizing the charging current and controlling the generation of the SEI layer, excessive current density can be avoided to cause battery aging. The linear decay charging strategy can balance the charging speed and battery life, ensuring that the battery is safely charged with high efficiency.

[0108] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0109] In the present invention, a state of charge equation describing the change of lithium battery power with 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 SEI layer generation current closely related to the SEI layer generation rate are determined, the SEI layer generation process is digitized, and then the lithium battery capacity loss is solved, so as to effectively inhibit its generation by controlling the charging current, and a charging current linear attenuation equation that is convenient and quickly solved is established to regulate the charging current, increase the charging current regulation response speed, and then combine the charging current optimization equation with the goal of minimizing capacity loss, 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, the charging current is quickly adjusted to the expected charging current without overcharging and not exceeding the traditional constant current and constant voltage charging time, effectively avoiding excessive generation of the SEI layer, reducing the lithium battery capacity loss during the charging process while ensuring that the charging efficiency is not lost, and improving the charging safety and life of the lithium battery.

[0110] Reference Manual Attached Figure 2 , showing a schematic structural diagram of a lithium battery adaptive charging system provided by the present invention.

[0111] The present invention further provides a lithium battery adaptive charging system 20, which is applied to the above-mentioned lithium battery adaptive charging method, comprising:

[0112] Processor 201.

[0113] The memory 202 stores computer-readable instructions. When the computer-readable instructions are executed by the processor 201, the lithium battery adaptive charging method of the method embodiment is implemented.

[0114] The lithium battery adaptive charging system 20 provided by the present invention can execute the above-mentioned lithium battery adaptive charging method and achieve the same or similar technical effects. To avoid repetition, the present invention will not go into details.

[0115] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0116] In the present invention, a state of charge equation describing the change of lithium battery power with 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 SEI layer generation current closely related to the SEI layer generation rate are determined, the SEI layer generation process is digitized, and then the lithium battery capacity loss is solved, so as to effectively inhibit its generation by controlling the charging current, and a charging current linear attenuation equation that is convenient and quickly solved is established to regulate the charging current, increase the charging current regulation response speed, and then combine the charging current optimization equation with the goal of minimizing capacity loss, 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, the charging current is quickly adjusted to the expected charging current without overcharging and not exceeding the traditional constant current and constant voltage charging time, effectively avoiding excessive generation of the SEI layer, reducing the lithium battery capacity loss during the charging process while ensuring that the charging efficiency is not lost, and improving the charging safety and life of the lithium battery.

[0117] 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.

[0118] 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).

[0119] 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.

[0120] 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.

[0121] 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.

[0122] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0123] 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.

[0124] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described equipment, devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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 lithium battery adaptive charging method as described in the method embodiment is implemented.

[0130] A computer-readable storage medium provided by the present invention can implement the steps and effects of the lithium battery adaptive charging method of the above method embodiment. To avoid repetition, the present invention will not go into details.

[0131] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0132] In the present invention, a state of charge equation describing the change of lithium battery power with 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 SEI layer generation current closely related to the SEI layer generation rate are determined, the SEI layer generation process is digitized, and then the lithium battery capacity loss is solved, so as to effectively inhibit its generation by controlling the charging current, and a charging current linear attenuation equation that is convenient and quickly solved is established to regulate the charging current, increase the charging current regulation response speed, and then combine the charging current optimization equation with the goal of minimizing capacity loss, 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, the charging current is quickly adjusted to the expected charging current without overcharging and not exceeding the traditional constant current and constant voltage charging time, effectively avoiding excessive generation of the SEI layer, reducing the lithium battery capacity loss during the charging process while ensuring that the charging efficiency is not lost, and improving the charging safety and life of the lithium battery.

[0133] 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.

[0134] There are a few points to note:

[0135] (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.

[0136] (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.

[0137] (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.

[0138] 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 lithium battery adaptive charging method, characterized in that: include: S1: Establish the state of charge equation that describes the change of lithium battery power with charging current; S2: Calculate 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 by combining the positive electrode current density and the negative electrode current density and using the BV kinetic equation describing the charge transfer process; S4: determining the SEI layer overpotential related to the SEI layer generation 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 generated 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, a charging current optimization equation is established with the goal of minimizing the capacity loss, 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 the charging current optimization equation is solved to obtain the expected charging current; S9: charging the lithium battery with the expected charging current.

2. The lithium battery adaptive charging method according to claim 1, characterized in that: The charge state equation is specifically: Among them, SOC and SOC0 represent the state of charge and the initial state of charge respectively, t and t0 represent the current time and the charging start time respectively, I represents the charging current, Q max Indicates the maximum charge capacity of a 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: Among them, j neg and j pos They represent the positive electrode current density and the negative electrode current density respectively, F represents the Faraday constant, and a neg and l neg Respectively represent the specific surface area and thickness of the negative electrode of the lithium battery, a pos and l pos Respectively represent the specific surface area and thickness of the positive electrode of the lithium battery.

4. The lithium battery adaptive charging method according to claim 1, characterized in that: The S3 specifically includes: S301: Establish the BV kinetic equation: Among them, j k and j k,0 They represent the k-electrode reaction current density and the k-electrode standard reaction current density, i.e., the exchange current density. sinh represents the hyperbolic sine function. R g represents the gas constant, T represents the absolute temperature, and They represent the solid phase potential, liquid phase potential and open circuit potential of the k electrode respectively, where k represents an indicator variable, k=pos or neg, when k=pos it represents the positive electrode of the lithium battery, when k=neg it represents the negative electrode of the 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: Among them, sinh -1 represents the inverse function of the hyperbolic sine function, J pos and J 0,pos represent the positive electrode current density and the positive electrode standard exchange current density respectively; S303: Calculate the internal charging voltage according to the positive electrode solid phase potential and the negative electrode solid phase potential: Among them, V cell 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: Among them, U0 represents the open circuit voltage of the lithium battery, R represents the internal resistance of the lithium battery, and I 0,a and I 0,c They represent the positive standard current and negative standard current of the lithium battery respectively.

5. The lithium battery adaptive charging method according to claim 1, characterized in that: The SEI layer overpotential is specifically: j SEI =-i 0,SEI a neg exp[αnη SEI ] or SEI =φ s -f l -R film j tot -U SEI or SEI =U n -U SEI +n n Among them, j SEI represents the SEI layer side reaction current density, i 0,SEI represents the SEI layer side reaction exchange current density, η SEI represents the SEI layer overpotential, n represents the number of electron transfers, R film represents the SEI layer impedance, U SEI represents the SEI layer potential, α=0.5 represents the electrochemical transfer coefficient, exp represents the exponential function, U n Indicates the open circuit potential of the negative electrode of the lithium battery, j n Represents the Faraday current density of the negative electrode of the lithium battery, η n Indicates the negative electrode overpotential of lithium battery. It represents the exchange current density of the negative electrode of lithium battery.

6. The lithium battery adaptive charging method according to claim 5, characterized in that: The SEI layer generates a current specifically as follows: Among them, I Sei represents the current generated by the SEI layer, I 0,Sei represents the SEI layer side reaction exchange current, U Sei ref =0.4 represents the reference potential of the side reaction of the SEI layer.

7. The lithium battery adaptive charging method according to claim 1, characterized in that: The relationship function is specifically: Among them, Q loss Indicates capacity loss.

8. The lithium battery adaptive charging method according to claim 1, characterized in that: The charging current linear decay equation is specifically: I=I1-I2t Among them, I1 represents the initial charging current, and I2 represents the charging current decay rate.

9. The lithium battery adaptive charging method according to claim 8, characterized in that: The charging current optimization equation is specifically: min Q loss St I des =I1-I2t SOC(t max )=1 I des” I max t max” t CC-CV Among them, min means taking the minimum value, St means the constraint condition, SOC(t max ) indicates the maximum charging time t max The state of charge at t CC-CV Indicates the charging time of lithium battery under constant current and constant voltage charging, that is, the expected charging time, V max Indicates the maximum allowable charging voltage of the lithium battery, that is, the expected charging voltage, I max Indicates the maximum allowable charging current of the lithium battery, SOC max Indicates the maximum state of charge, I des Indicates the expected charging current.

10. 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 9 is implemented.

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