Battery charging method, control device and computer readable storage medium

Abstract

The invention relates to the technical field of battery charging, particularly provides a battery charging method, a control device and a computer readable storage medium, and aims to solve the problem that the capacity and the service life of a battery are affected by lithium precipitation side reaction generated in the battery when the battery encounters severe working conditions in the charging process. In order to achieve the purpose, the charging method comprises the steps that the actual current value of a battery in the charging process is monitored; judging whether the actual current value is greater than or equal to an over-current threshold value, wherein the over-current threshold value is determined based on the state of charge and the temperature of the battery; and when the actual current value is greater than or equal to the overcurrent threshold value, stopping charging and discharging the battery. By monitoring the actual current value in the battery charging process and discharging the battery when the actual current value exceeds the overcurrent threshold value, the lithium metal generated in the overcurrent charging process can be quickly dissolved and recovered before obvious lithium dendrites are not formed in lithium precipitation, so that the risk of battery capacity fading is reduced, and the battery charging efficiency is improved. The cycle life of the battery is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of battery charging, and specifically provides a charging method, a control device and a computer-readable storage medium for a battery. Background Art

[0002] In response to the call for energy conservation and environmental protection, rechargeable batteries are now more and more widely used in various fields such as smart homes and new energy vehicles.

[0003] When charging a battery, various charging parameters such as the charging rate and charging duration play an important role in the electrochemical reaction inside the battery. Under some harsh working conditions, such as battery system failures and charging pile failures, the charging parameters will change rapidly, thus affecting the stability of the electrochemical reaction inside the battery, causing a serious lithium plating side reaction inside the battery, thereby reducing the battery capacity and cycle life, and possibly increasing the safety risk of the battery.

[0004] Correspondingly, a new charging solution is needed in this field to solve the above problems. Summary of the Invention

[0005] The present application aims to solve the above technical problems, that is, to solve the problem that when the battery encounters harsh working conditions during charging, a lithium plating side reaction occurs inside the battery, thereby affecting the battery capacity and service life.

[0006] In a first aspect, the present application provides a charging method for a battery, which includes the following steps:

[0007] Monitor the actual current value of the battery during the charging process;

[0008] Judge whether the actual current value is greater than or equal to an overcurrent threshold, and the overcurrent threshold is determined based on the state of charge and temperature of the battery;

[0009] When the actual current value is greater than or equal to the overcurrent threshold, stop charging the battery and discharge the battery.

[0010] In the case of adopting the above technical solution, during the charging process of the battery, by monitoring the actual current value during the charging process, when the actual current value is greater than or equal to the overcurrent threshold, it is judged that the battery has an overcurrent charging phenomenon, that is, lithium plating occurs, and then the charging is stopped and the battery is discharged, which can avoid the further deterioration of the lithium plating phenomenon. At the same time, before the lithium plating does not form obvious lithium dendrites, the lithium metal generated during the overcurrent charging process is quickly dissolved and recovered, thereby reducing the risk of battery capacity attenuation and improving the cycle life of the battery.

[0011] In a technical solution of the above charging method, the charging method further includes:

[0012] Obtain the overcurrent I overch and the overcurrent time t overch ;

[0013] According to the overcurrent I overch and the overcurrent time t overch Judge the discharge amount, and discharge the battery or charge the battery.

[0014] In the case of adopting the above technical solution, the discharge amount in the discharge stage is controlled. When the discharge amount meets the requirement and the lithium metal precipitated during the overcurrent charging process is fully recovered, it is changed to the charging state, thereby avoiding energy waste.

[0015] In a technical solution of the above charging method, the charging method further includes:

[0016] Obtain the actual discharge current I disch and the discharge time t disch ;

[0017] The step of "judging the discharge amount according to the overcurrent I overch and the overcurrent time t overch and discharging the battery or charging the battery" includes:

[0018] When , control to charge the battery; and / or

[0019] When , control to discharge the battery.

[0020] In the case of adopting the above technical solution, taking the integral area value of the discharge current I disch and the overcurrent I overch along the time axis as the judgment condition for whether the lithium precipitation is fully recovered, not only can the lithium precipitation generated in the overcurrent charging stage be fully recovered, reducing the risk of lithium dendrite formation, but also can avoid prolonging the time of the entire charging process due to excessive discharge, improving the charging efficiency.

[0021] In a technical solution of the above charging method, the step of "discharging the battery" includes:

[0022] Discharge the battery in pulses.

[0023] In the case of adopting the above technical solution, it is beneficial to control the discharge amount and control the battery to change to the charging state or continue to discharge according to the specific value of the discharge amount.

[0024] In a technical solution of the above charging method, the step of "discharging the battery in pulses" includes:

[0025] Determine the preset discharge current;

[0026] The battery is pulsed-discharged based on the preset discharge current.

[0027] In the case of adopting the above technical solution, the discharge current during the pulsed discharge is determined based on the preset discharge current, so that the discharge current is maintained within a reasonable range. This can not only avoid damaging the internal structure of the battery due to excessive discharge current, but also avoid prolonging the entire charging process time and reducing the charging efficiency due to too small discharge current.

[0028] In a technical solution of the above charging method, the step of "determining the preset discharge current" includes:

[0029] According to the overcurrent I overch and the overcurrent time t overch the preset discharge current is determined.

[0030] In the case of adopting the above technical solution, the amount of lithium plating can be determined according to the overcurrent I overch and the overcurrent time t overch and then the preset discharge current is determined according to the magnitude of the amount of lithium plating.

[0031] In a technical solution of the above charging method, the step of "determining the preset discharge current" includes:

[0032] The preset discharge current is determined according to the state of charge and / or temperature of the battery.

[0033] In the case of adopting the above technical solution, determining the preset discharge current according to the actual state of the battery can effectively protect the battery.

[0034] In a technical solution of the above charging method, before monitoring the actual current value during the charging process, the charging method further includes:

[0035] Determine the fast charging current according to the state of charge and / or temperature of the battery;

[0036] The battery is charged based on the fast charging current.

[0037] In a second aspect, the present application provides a control device, which includes a processor and a storage device. The storage device is adapted to store multiple program codes, and the program codes are adapted to be loaded and run by the processor to execute the charging method according to any one of the first aspect.

[0038] In a third aspect, the present application provides a computer-readable storage medium, which stores multiple program codes, and the program codes are adapted to be loaded and run by a processor to execute the charging method according to any one of the first aspect. Brief Description of the Drawings

[0039] Referring to the accompanying drawings, the disclosure of the present application will become more readily understandable. It is easily understood by those skilled in the art that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present application. In addition, similar numbers in the figures are used to represent similar components, where:

[0040] Figure 1 is a schematic flow chart of the main steps of a charging method according to an embodiment of the present application;

[0041] Figure 2 is a schematic flow chart of the detailed steps of a charging method according to an embodiment of the present application.

[0042] Figure 3 is a schematic diagram of the process of the charging current changing with time during the battery charging process. Detailed Embodiments

[0043] Some embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present application and are not intended to limit the scope of protection of the present application. Those skilled in the art can make adjustments according to needs to adapt to specific application scenarios.

[0044] In the description of the present application, a "processor" may include hardware, software, or a combination of both. A processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor, or any other suitable processor. The processor has data and / or signal processing functions. The processor can be implemented in software, in hardware, or in a combination of both. A non-transitory computer-readable storage medium includes any suitable medium for storing program code, such as magnetic disks, hard disks, optical disks, flash memories, read-only memories, random access memories, and the like. The term "A and / or B" represents all possible combinations of A and B, such as only A, only B, or A and B. The term "at least one A or B" or "at least one of A and B" has a meaning similar to "A and / or B" and may include only A, only B, or A and B.

[0045] During the charging process of the battery, the maximum thresholds of the various charging parameters that the battery can accept are different at different temperatures and states of charge. Under some harsh working conditions, when some charging parameters exceed the maximum thresholds that the battery can accept, it will affect the balance of the electrochemical reactions inside the battery, causing serious polarization phenomena inside the battery, thereby reducing the capacity and cycle life of the battery. Therefore, adjusting the charging method plays a crucial role in improving the service life of the battery.

[0046] This application takes a lithium battery as an example for illustration. When a lithium battery operates for a long time under conditions such as high-rate charging or low-temperature charging, lithium plating will occur. Therefore, the current adjustment strategy for lithium battery charging mainly focuses on how to prevent lithium plating, rather than remedying the lithium plating phenomenon that has occurred during the charging process. As a result, the lithium metal deposited on the surface of the battery negative electrode during the charging process forms "dead lithium", that is, lithium dendrites, which causes the battery capacity to decay.

[0047] When a lithium battery encounters adverse conditions (such as battery system failures, charging pile failures, etc.) during the charging process, the charging current is higher than the maximum current threshold at the temperature and state of charge of the battery. At this time, the electron transfer rate inside the battery is higher than the rate of lithium ions inserting into the negative electrode graphite layer. A large number of electrons accumulated at the negative electrode will reduce the lithium ions that have not been inserted into the graphite to lithium metal and deposit it on the surface of the negative electrode. By analyzing the transient potential distribution inside the battery during the overcurrent lithium plating process, it can be known that the potential of graphite lithium insertion is higher than the deposition potential of lithium metal. Therefore, converting the battery to a discharge state at this time will cause the precipitated lithium metal to dissolve, preventing the overcurrent charging from further deteriorating the lithium plating phenomenon.

[0048] Based on the above principle, referring to Figure 1 , which is the main step flowchart of a charging method for a battery disclosed in this application, taking the charging process of a lithium battery as an example for illustration, the charging method includes the following steps:

[0049] S101: Monitor the actual current value of the battery during the charging process.

[0050] Before step S101, when the BMS (Battery Management System) starts charging the battery, the BMS first requests the initial charging current I0 according to the temperature and state of charge of the battery, and starts charging with the initial charging current I0. At this time, the actual current value is I0.

[0051] In an implementation manner of this application, the charging method is applicable to fast charging. When a fast charging request is issued, the BMS also requests the initial charging current I0 under fast charging conditions according to the temperature and state of charge of the battery.

[0052] During the charging process, when the charging conditions change, the actual current value will change. Therefore, the actual current value during the charging process is monitored in real time through step S101.

[0053] S102: Determine whether the actual current value is greater than or equal to the overcurrent threshold.

[0054] It should be noted that the overcurrent threshold refers to the maximum current value that the circuit allows to pass during the charging process, and the overcurrent threshold is determined based on the current state of charge and temperature of the battery. That is, the overcurrent threshold is not a fixed value. The overcurrent threshold of the battery is different under different states of charge and temperatures, so it is a dynamic value that changes according to different states of the battery. The specific value of the overcurrent threshold is obtained through experiments or numerical simulations in the early stage. For example, experiments can be carried out by the trial current method or the three-electrode measurement method, using the state of charge and temperature values as characteristic quantities, collecting the corresponding overcurrent thresholds under different states of charge and temperatures, establishing the mapping relationship between the state of charge, temperature, and overcurrent threshold, and storing the finally formed data model in the cloud database. During the battery charging process, the BMS can obtain the overcurrent threshold of the battery in different states from the database in real time. The above method of establishing the model is a well-known technology in the art, and this application will not elaborate too much here.

[0055] For example, in an application scenario of this application, a lithium battery is applied in a new energy vehicle, and a charging pile is used to quickly charge the vehicle. The data model established between the state of charge, temperature, and overcurrent threshold of the battery is stored in the vehicle network system. During the charging process, the BMS directly obtains the overcurrent threshold from the vehicle network system.

[0056] S103: When the actual current value is greater than or equal to the overcurrent threshold, stop charging the battery and discharge the battery.

[0057] At any time node during the charging process, when it is monitored that the actual current value is greater than the overcurrent threshold, stop charging and discharge the battery. It should be understood that the electric energy during the discharging process can be absorbed by power devices such as battery heaters. For new energy vehicles, the energy during the discharging process can be converted into the heat of the engine.

[0058] In practical applications, when the actual current value in step S103 is greater than or equal to the overcurrent threshold, that is, the reason for overcurrent charging may be battery system failure, charging pile failure, or communication delay, etc. Under the above working conditions, the current value may increase rapidly.

[0059] Refer to Figure 2 , which is a detailed step flowchart of the charging method provided by this application. Based on steps S101 - S103, after step S103, the charging method further includes:

[0060] S104: Obtain the overcurrent I overch and the overcurrent time t overch .

[0061] It should be explained that the overcurrent I overch refers to the actual current value corresponding to when the charging current exceeds the overcurrent threshold, and the overcurrent time t overchRefers to the charging time of the battery at the overcurrent I overch In actual application scenarios, when the BMS system confirms that the actual current is greater than or equal to the overcurrent threshold, the system will have a short confirmation process, that is, to confirm whether the information of the actual current value is accurate to prevent misjudgment. This indicates that there is a certain delay in the confirmation process of the system. Therefore, when the actual current value is greater than the overcurrent threshold, charging will continue for a period of time, and overcurrent charging occurs during this period. Of course, there will also be delays in information interaction inside devices such as charging piles in practice, and overcurrent charging phenomena will also occur at this time.

[0062] According to the actual situation, the overcurrent I overch can be a pulsed current. That is, when a battery system failure or a charging pile failure occurs, the actual current value suddenly jumps to a larger value, or in some other scenarios, the actual current value is in a gradually increasing state. At this time, the overcurrent I overch is also in a gradually rising state.

[0063] S105: Obtain the actual discharge current I disch and the discharge time t disch .

[0064] It should be explained that the actual discharge current I disch refers to the real-time current value during the discharge process, and the discharge time t disch refers to the discharge time at the actual discharge current I disch .

[0065] Similarly, the actual discharge current I disch can be a pulsed current or a current in dynamic change. For the convenience of controlling the discharge process, in an implementation manner of the present application, the actual discharge current I disch adopts a pulsed current, that is, in step S103, the step of "discharging the battery" adopts a pulsed discharge method.

[0066] It should be noted that although the present application limits the order of step S104 and step S105, it does not constitute a limitation to the present application. That is, in actual applications, step S105 can also be performed first and then step S104, or step S104 and step S105 can be performed simultaneously. Their sequence will not affect the charging process. Therefore, the corresponding adjustments to the sequence of the above steps S104 and S105 are all within the protection scope of the present application.

[0067] S106: According to the overcurrent I overch , the overcurrent time t overch , the discharge current I disch and the discharge time t dischDetermine whether the discharge capacity meets the requirements.

[0068] Specifically, in an implementation manner of the present application, in step S106, and are used as the judgment criteria, that is, to judge whether is greater than or equal to

[0069] When , the following steps are executed:

[0070] Step S107: Control the battery to charge.

[0071] When the battery changes from the discharge state to the charge state, it can continue to charge with the initial charging current I0, and then continue to monitor the actual current value during the charging process, that is, repeat the above steps.

[0072] It can be understood that when , it means that the discharge capacity does not meet the requirements, and the battery needs to be controlled to continue discharging until the discharge capacity meets the requirements and then step S107 is executed.

[0073] Referring to Figure 3 , it is a schematic diagram of the change of the charging current with time during the charging process. is the area value of part A in the figure, which represents the accumulation of the charge amount during the charging process with the overcurrent I overch . The area value of part A is quantified as the amount of lithium deposition generated during the overcurrent charging process. is the area value of part B in the figure, which represents the accumulation of the charge amount during the discharging process with the discharging current I disch . The area value of part B is quantified as the recovery amount of lithium metal during the discharging process. Therefore, during the discharging process, the area of part B is made greater than or equal to the area of part A, so that the lithium metal precipitated during the overcurrent charging process can be dissolved and recovered to the maximum extent, thereby reducing the risk of forming lithium dendrites as much as possible.

[0074] As an implementation manner of the present application, in the step of "performing pulsed discharge on the battery", first determine the preset discharge current, and then perform pulsed discharge based on the preset discharge current.

[0075] The preset discharge current is a pulsed current value estimated before performing the pulsed discharge. The preset discharge current can be understood as a requested current value in the initial stage of the discharging process, and the above-mentioned discharge current I disch is an actual current value based on the preset discharge current. The magnitude of the discharge current I disch may have some deviation from the value of the preset discharge current, but the difference is not too large. Therefore, the preset discharge current is a reference value and is for the discharge current Idisch Limitations

[0076] The magnitude of the preset discharge current should be avoided being too large or too small. When the preset discharge current is too large, it will cause the battery temperature to rise rapidly, damaging the internal structure of the battery. Moreover, according to Figure 3 it can be known that when the preset discharge current is too large, it will cause the discharge time t disch to be too short, then it will be not conducive to controlling the discharge process. Similarly, according to Figure 3 , when the preset discharge current is too small, it will cause t disch to be too long, thus prolonging the time of the entire charging process and reducing the charging efficiency. Therefore, determining a reasonable preset discharge current to keep the discharge current I disch within a reasonable range value can not only protect the battery, but also improve the charging efficiency.

[0077] In some implementation manners, the preset discharge current can be determined according to the overcurrent I overch and the overcurrent time t overch , that is, the preset discharge current is determined according to the amount of lithium deposition during the overcurrent charging process. For example, on the premise of not affecting the battery performance, if the amount of lithium deposition is large, the preset discharge current can be appropriately increased to reduce the charging time.

[0078] In other implementation manners, the preset discharge current can also be determined according to the current state of charge of the battery and / or the current temperature of the battery. It can be understood that the battery can withstand different magnitudes of discharge current at different states of charge and temperatures. For example, during the overcurrent charging stage, due to the too large actual current value, the battery temperature increases sharply. At this time, when the battery changes to the discharge state, the magnitude of the preset discharge current can be correspondingly reduced to prevent the internal chemical reaction of the battery from accelerating when operating at a higher discharge current under high temperature conditions, resulting in battery capacity attenuation. Similarly, if the current state of charge of the battery is high, the preset discharge current can be appropriately reduced, and if the current state of charge of the battery is low, the preset discharge current can be appropriately increased. Therefore, the current state of the battery is also of great significance for determining the preset discharge current.

[0079] Of course, in practical applications, the preset discharge current can also be determined by combining the overcurrent I overch , the overcurrent time t overch , the current state of charge of the battery, and the temperature of the battery, etc., aiming to maximize the charging efficiency on the premise of ensuring that the battery structure is not damaged, or determined according to several of the above factors. The present application does not make specific limitations on this.

[0080] During the charging process of the battery in this application, by monitoring the actual current value during charging, when the actual current value is greater than or equal to the overcurrent threshold, it is determined that the battery has experienced overcurrent charging, that is, lithium deposition occurs. Then, the charging is stopped and the battery is discharged, which can prevent the lithium deposition phenomenon from deteriorating further. At the same time, before the lithium deposition forms obvious lithium dendrites, the lithium metal generated during the overcurrent charging process is quickly dissolved and recycled, thereby reducing the risk of battery capacity attenuation and improving the cycle life of the battery.

[0081] At the same time, during the discharging stage of the charging process in this application, with the discharging current I disch and the overcurrent I overch The integral area value along the time axis is used as the judgment condition for whether the lithium deposition is fully recycled. It can not only fully recycle the lithium deposition generated during the overcurrent charging stage, reduce the risk of lithium dendrite formation, but also effectively control the discharging amount during the discharging stage and avoid energy waste.

[0082] During the rapid charging process of the vehicle, due to system abnormalities and other reasons, the possibility of overcurrent phenomenon is relatively high. Therefore, through this application, the lithium metal deposited on the negative electrode surface of the battery during the overcurrent charging process is dissolved and recycled, effectively solving the problem of battery capacity attenuation that may occur during the rapid charging process on the premise of achieving the purpose of rapid charging.

[0083] It should be noted that although this application has made an exemplary description for lithium batteries, it does not constitute a limitation to this application, that is, the charging method of this application is also applicable to other types of batteries to prevent polarization phenomena from occurring inside the battery during long-term charging.

[0084] It should be pointed out that although the above embodiments describe the various steps in a specific order, those skilled in the art can understand that in order to achieve the effects of this application, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the protection scope of this application.

[0085] Furthermore, this application also provides a control device. In an embodiment of the control device according to this application, the control device includes a processor and a storage device. The storage device can be configured to store a program for executing the charging method in any of the above method embodiments, and the processor can be configured to execute the program in the storage device. The program includes, but is not limited to, the program for executing the charging method described in the above method embodiments. In some embodiments of this application, the control device can be a control device formed by various electronic devices.

[0086] Furthermore, the present application also provides a computer-readable storage medium. In an embodiment of the computer-readable storage medium according to the present application, the computer-readable storage medium may be configured to store a program for executing the charging method in the above method embodiment. The program may be loaded and run by a processor to implement the above charging method. For ease of description, only the parts related to the embodiments of the present application are shown. For specific technical details not disclosed, please refer to the method part of the embodiments of the present application. The computer-readable storage medium may be a storage device formed by various electronic devices. Optionally, the computer-readable storage medium in the embodiments of the present application is a non-transitory computer-readable storage medium.

[0087] Those skilled in the art can understand that all or part of the processes in the methods of the above embodiments of the present application can also be completed by instructing relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable storage medium may include: any entity or device, medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal, telecommunication signal, and software distribution medium that can carry the computer program code. It should be noted that the content included in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0088] So far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the drawings. However, those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principle of the present application, those skilled in the art can make equivalent changes or substitutions to relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present application.

Claims

1. A charging method for a battery, characterized in that, Comprising: Monitoring the actual current value of the battery during charging; Judging whether the actual current value is greater than or equal to an overcurrent threshold, the overcurrent threshold being determined based on the state of charge and temperature of the battery; When the actual current value is greater than or equal to the overcurrent threshold, stopping charging the battery and discharging the battery.

2. The charging method according to claim 1, characterized in that, The charging method further comprises: Obtain the overcurrent I overch and the overcurrent time t overch ; According to the overcurrent I overch and the overcurrent time t overch judge the discharge capacity, and discharge or charge the battery.

3. The charging method according to claim 2, characterized in that, The charging method further comprises: Obtain the actual discharge current I disch and the discharge time t disch ; The step of "judging the discharge capacity according to the overcurrent I overch and the overcurrent time t overch to discharge or charge the battery" includes: When control charging of the battery; and / or When control the discharge of the battery.

4. The charging method according to claim 2, characterized in that, The step of "discharging the battery" comprises: Performing pulsed discharge on the battery.

5. The charging method according to claim 4, characterized in that, The step of "performing pulsed discharge on the battery" comprises: Determining a preset discharge current; Performing pulsed discharge on the battery based on the preset discharge current.

6. The charging method according to claim 5, characterized in that, The step of "determining a preset discharge current" comprises: Based on the overcurrent I overch and the overcurrent time t overch determine the preset discharge current.

7. The charging method according to claim 5, characterized in that, The step of "determining a preset discharge current" comprises: Determining the preset discharge current according to the state of charge and / or temperature of the battery.

8. The charging method according to any one of claims 1 to 7, characterized in that, Before monitoring the actual current value during the charging process, the charging method further comprises: Determining a fast charge current according to the state of charge and / or temperature of the battery; Charging the battery based on the fast charge current.

9. A control device, comprising a processor and a storage device, the storage device being adapted to store a plurality of program codes, characterized in that, The program code is adapted to be loaded and run by the processor to execute the charging method according to any one of claims 1 to 8.

10. A computer-readable storage medium, in which a plurality of program codes are stored, characterized in that, The program code is adapted to be loaded and run by a processor to execute the charging method according to any one of claims 1 to 8.

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