A charging method and charging device for lithium-ion batteries

Abstract

This application provides a charging method and charging device for lithium-ion batteries. The charging method includes: formulating a charging strategy based on the corresponding State of Charge (SOC) at different temperatures; charging the battery according to the formulated charging strategy; collecting the potential and charging current of the first electrode at the current charging rate, and determining the voltage drop of the first electrode between any two moments; calculating the charging DC internal resistance of the battery based on the first voltage drop and charging current between the first and second moments; calculating the critical current at the current temperature and current SOC based on the second voltage drop of the first electrode at a third moment and the critical lithium plating moment, and the charging DC internal resistance; charging any battery of the same type, and controlling the charging current to be less than the critical current based on the battery temperature and SOC during charging. This method and device can overcome the problem of lithium-ion battery failure during charging.

Description

Technical Field

[0001] This application relates to the field of power battery technology, and in particular to a charging method and charging device for lithium-ion batteries. Background Technology

[0002] With the increasing popularity of electric vehicles, safety issues have garnered growing attention, significantly hindering their adoption. One major safety concern is the failure of the power battery within the vehicle. Power batteries include lithium-ion batteries, nickel-metal hydride batteries, fuel cells, and lead-acid batteries. Specifically for lithium-ion batteries, one cause of failure is exceeding the critical charging current or rate during charging. This can lead to lithium plating at the negative electrode. The deposited lithium dendrites pose a risk of piercing the battery separator, causing an internal short circuit and ultimately resulting in battery failure.

[0003] Therefore, if safe charging conditions that prevent lithium plating in lithium-ion batteries can be determined in advance, and the lithium-ion batteries are charged within the safe charging range indicated by these safe charging conditions during the charging process, lithium-ion battery failure during charging can be greatly avoided. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a charging method and charging device for lithium-ion batteries, which can overcome the problem of lithium-ion battery failure caused during the charging process.

[0005] In a first aspect, embodiments of this application provide a charging method for a lithium-ion battery, the charging method comprising:

[0006] Based on the SOC corresponding to different temperatures, a charging strategy is formulated, including the charging rate at different SOCs at each temperature.

[0007] The battery is charged according to the established charging strategy, that is, any temperature and any state of charge are selected, and the battery is charged according to the predetermined charging rate.

[0008] Collect the potential and charging current of the first electrode at the current charging rate, and determine the voltage drop of the first electrode between any two moments;

[0009] The charging DC internal resistance of the battery is calculated based on the first voltage drop and charging current of the first electrode between the first and second moments.

[0010] Based on the second voltage drop of the first electrode at the third moment and the critical lithium plating moment, and the charging DC internal resistance, the critical current at the current temperature and current SOC is calculated.

[0011] For any battery of the same type, the charging current is controlled to be less than the critical current based on the battery temperature and SOC during charging.

[0012] Optionally, after calculating the critical current at the current temperature and current SOC, the charging method further includes:

[0013] Based on the relationship between charging current and charging rate, the critical current is converted into the critical charging rate.

[0014] Optionally, the first moment is the start of charging, and the second moment is the end of charging.

[0015] Optionally, the temperature range includes -20℃ to 25℃; the SOC range includes 0% to 95%.

[0016] Optionally, each temperature corresponds to multiple SOCs, and each SOC corresponding to each temperature corresponds to a charging rate.

[0017] Optionally, the third time point is the time when charging begins.

[0018] Optionally, the battery is a three-electrode lithium-ion battery, wherein the electrodes of the three-electrode lithium-ion battery are a positive electrode, a negative electrode, and a reference electrode.

[0019] Optionally, the first electrode is the negative electrode of a three-electrode lithium-ion battery.

[0020] Secondly, embodiments of this application provide a charging device for a lithium-ion battery, the charging device comprising:

[0021] A storage module is used to store data, including a charging strategy based on the SOC corresponding to different temperatures: the charging strategy includes the charging rate at different SOCs corresponding to each temperature.

[0022] The pre-charge module is used to charge the battery according to a predetermined charging strategy, that is, to select any temperature and any SOC and charge it according to a predetermined charging rate.

[0023] The monitoring module is used to collect the potential and charging current of the first electrode at the current charging rate and determine the voltage drop of the first electrode between any two moments.

[0024] The first calculation module is used to calculate the charging DC internal resistance of the battery based on the first voltage drop and charging current of the first electrode between the first time and the second time.

[0025] The second calculation module is used to calculate the critical current at the current temperature and current SOC based on the second voltage drop of the first electrode at the third time and the critical lithium plating time and the charging DC internal resistance.

[0026] The charging module is used to charge any battery of the same type. Based on the battery temperature and SOC during charging, it controls the charging current to be less than the critical current.

[0027] Thirdly, embodiments of this application provide a computer-readable storage medium storing a computer program that, when executed by a processor, performs the steps of the lithium-ion battery charging method described above.

[0028] The lithium-ion battery charging method and charging device provided in this application embodiment can predetermine the safe charging conditions of the lithium-ion battery and charge the lithium-ion battery according to the safe charging conditions, thereby overcoming the problem of lithium-ion battery failure caused during the charging process.

[0029] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This application illustrates a method for charging a lithium-ion battery according to an exemplary embodiment.

[0032] Figure 2 The critical charge rate curve of the battery obtained by the charging method according to the present application at a temperature of 25°C is shown in an exemplary embodiment of the present application.

[0033] Figure 3 A schematic diagram of the structure of a lithium-ion battery charging device provided in an exemplary embodiment of this application is shown;

[0034] Figure 4 A schematic diagram of the structure of an electronic device provided by an exemplary embodiment of this application is shown. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.

[0036] Currently, one reason for lithium-ion battery failure is that during the charging process, the charging current exceeds the critical charging current or the charging rate exceeds the critical charging rate. In this case, lithium plating occurs at the negative electrode of the lithium-ion battery. The lithium dendrites that are deposited after lithium plating pose a risk of piercing the separator of the lithium-ion battery, thereby causing an internal short circuit and resulting in battery failure.

[0037] Therefore, if safe charging conditions that prevent lithium plating in lithium-ion batteries can be determined in advance, and the lithium-ion batteries are charged within the safe charging range indicated by these safe charging conditions during the charging process, lithium-ion battery failure can be greatly avoided.

[0038] Based on this, embodiments of this application provide a charging method and charging device for lithium-ion batteries, which can overcome the problem of lithium-ion battery failure caused during the charging process.

[0039] Please see Figure 1 , Figure 1 A flowchart illustrating a charging method for a lithium-ion battery provided in an exemplary embodiment of this application is shown;

[0040] like Figure 1 As shown in the exemplary embodiment of this application, a charging method for a lithium-ion battery includes the following steps:

[0041] S101. Formulate a charging strategy based on the SOC corresponding to different temperatures: including formulating the charging rate at different SOCs at each temperature.

[0042] Here, the temperature range can include -20℃ to 25℃, and the SOC range can include 0% to 95%.

[0043] Here, each temperature corresponds to multiple SOCs, and each SOC at each temperature corresponds to a charging rate. Therefore, a charging strategy can be formulated based on the SOC at different temperatures.

[0044] As an example, the established charging strategy can be summarized in the following table:

[0045]

[0046]

[0047] S102. Charge the battery according to the established charging strategy, that is, select any temperature and any SOC, and charge according to the predetermined charging rate.

[0048] Here, the battery is a three-electrode lithium-ion battery, and the electrodes of the three-electrode lithium-ion battery are a positive electrode, a negative electrode, and a reference electrode.

[0049] As an example, a three-electrode lithium-ion battery can be obtained in the following way:

[0050] First, a copper wire is fixed between the negative electrode and the separator of the lithium-ion battery. Then, lithium is plated onto the surface of the copper wire to form a reference electrode (vs Li+ / Li). The lithium-ion battery with the reference electrode is then used as a three-electrode lithium-ion battery. As an example, the diameter of the copper wire can be 10–15 μm.

[0051] When charging a three-electrode lithium-ion battery according to a predetermined charging strategy, the following pretreatment operations can be performed on the three-electrode lithium-ion battery before selecting any temperature, any state of charge (SOC), and charging at a predetermined charging rate:

[0052] First, adjust the SOC of the three-electrode lithium-ion battery to the specified arbitrary SOC. Then, place the three-electrode lithium-ion battery at the specified arbitrary temperature for a predetermined period of time, for example, 100-180 minutes. By placing the three-electrode lithium-ion battery at the specified arbitrary temperature for the predetermined period of time, the battery cell can achieve temperature equilibrium. As an example, when the selected arbitrary temperature is 25°C and the selected arbitrary SOC is 30%, first adjust the SOC of the three-electrode lithium-ion battery to 30%, and then place the three-electrode lithium-ion battery at 25°C for 100 minutes.

[0053] Furthermore, the predetermined charging rate in step S102 can be obtained in response to a user-inputted charging rate within the range corresponding to any temperature and any state of charge (SOC).

[0054] As an example, the charging time range here can be 60s to 300s.

[0055] S103. Collect the potential and charging current of the first electrode at the current charging rate, and determine the voltage drop of the first electrode between any two moments.

[0056] Here, the first electrode is the negative electrode of a three-electrode lithium-ion battery, and the charging current can be 100A.

[0057] S104. Based on the first voltage drop and charging current of the first electrode between the first time and the second time, calculate the charging DC internal resistance of the battery.

[0058] The first moment is the start of charging, and the second moment is the end of charging.

[0059] As an example, in this step, the charging DC internal resistance of the battery can be calculated using the following formula based on the first voltage drop and charging current of the first electrode between the first and second moments:

[0060]

[0061] Where r is the DC internal resistance of the battery during charging; ΔU1 is the first voltage drop; and I1 is the charging current.

[0062] S105. Based on the second voltage drop of the first electrode at the third moment and the critical lithium plating moment and the charging DC internal resistance, calculate the critical current at the current temperature and the current SOC.

[0063] Here, the third moment refers to the moment when charging begins.

[0064] As an example, in this step, the critical current at the current temperature and current SOC can be calculated using the following formula based on the second voltage drop of the first electrode at the third time and the critical lithium plating time, and the charging DC internal resistance:

[0065]

[0066] Where I0 is the critical current at the current temperature and current SOC; ΔU2 is the second voltage drop.

[0067] Furthermore, as an example, after step S105, the critical current can be converted into the critical charging rate based on the relationship between the charging current and the charging rate.

[0068] For example, the critical current can be converted into the critical charge rate C0 using the following formula:

[0069]

[0070] Among them, C n This refers to the rated capacity of a three-electrode lithium-ion battery.

[0071] S106. Charge any battery of the same type, and control the charging current to be less than the critical current based on the battery temperature and SOC during charging.

[0072] Here, if the critical current is converted into the critical charging rate based on the relationship between charging current and charging rate, then when charging any battery of the same type, the charging rate can be controlled to be less than the critical charging rate based on the battery temperature and SOC during charging.

[0073] Please see Figure 2 , Figure 2 The critical charge rate curve of the battery obtained by the charging method according to the present application, provided by an exemplary embodiment of the present application, is shown at a temperature of 25°C.

[0074] The lithium-ion battery charging method provided by the exemplary embodiments of this application can predetermine the safe charging conditions of the lithium-ion battery and charge the lithium-ion battery according to the safe charging conditions, thereby overcoming the problem of lithium-ion battery failure caused during the charging process.

[0075] Please see Figure 3 , Figure 3 This application provides a schematic diagram of the structure of a lithium-ion battery charging device according to an exemplary embodiment. Figure 3 As shown, the charging device 300 includes:

[0076] Storage module 310 is used to store data, including a charging strategy based on the SOC corresponding to different temperatures: the charging strategy includes the charging rate at different SOCs corresponding to each temperature.

[0077] The pre-charge module 320 is used to charge the battery according to a predetermined charging strategy, that is, to select any temperature and any SOC and charge it according to a predetermined charging rate.

[0078] The monitoring module 330 is used to collect the potential and charging current of the first electrode at the current charging rate and determine the voltage drop of the first electrode between any two moments.

[0079] The first calculation module 340 is used to calculate the charging DC internal resistance of the battery based on the first voltage drop and charging current of the first electrode between the first time and the second time.

[0080] The second calculation module 350 is used to calculate the critical current at the current temperature and the current SOC based on the second voltage drop of the first electrode at the third time and the critical lithium plating time and the charging DC internal resistance.

[0081] The charging module 360 ​​is used to charge any battery of the same type. Based on the battery temperature and SOC during charging, it controls the charging current to be less than the critical current.

[0082] In one possible implementation, the charging device 300 further includes a conversion module 370 (not shown in the figure), which is used to convert the critical current into a critical charging rate based on the relationship between the charging current and the charging rate.

[0083] In one possible implementation, the first moment is the start of charging, and the second moment is the end of charging.

[0084] In one possible implementation, the temperature range includes -20°C to 25°C; the SOC range includes 0% to 95%.

[0085] In one possible implementation, each temperature corresponds to multiple SOCs, and each SOC corresponding to each temperature corresponds to a charging rate.

[0086] In one possible implementation, the third moment is the moment when charging begins.

[0087] In one possible implementation, the battery is a three-electrode lithium-ion battery, wherein the electrodes of the three-electrode lithium-ion battery are a positive electrode, a negative electrode, and a reference electrode.

[0088] In one possible implementation, the first electrode is the negative electrode of a three-electrode lithium-ion battery.

[0089] An exemplary embodiment of this application provides a lithium-ion battery charging device that can predetermine the safe charging conditions for the lithium-ion battery and charge the lithium-ion battery according to the safe charging conditions, thereby overcoming the problem of lithium-ion battery failure caused during the charging process.

[0090] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 4 As shown, the electronic device 400 includes a processor 410, a memory 420, and a bus 430.

[0091] The memory 420 stores machine-readable instructions that can be executed by the processor 410. When the electronic device 400 is running, the processor 410 and the memory 420 communicate via the bus 430. When the machine-readable instructions are executed by the processor 410, the steps of the method for determining the critical charging rate of a lithium-ion battery as described in the above method embodiment can be executed. For specific implementation details, please refer to the method embodiment, which will not be repeated here.

[0092] This application also provides a computer-readable storage medium storing a computer program. When the computer program is run by a processor, it can execute the steps of the lithium-ion battery charging method as described in the above method embodiments. For specific implementation details, please refer to the method embodiments, which will not be repeated here.

[0093] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0094] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0095] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0096] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0097] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0098] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for charging a lithium-ion battery, characterized in that, The charging method includes: Based on the SOC corresponding to different temperatures, a charging strategy is formulated, including the charging rate at different SOCs at each temperature. The battery is charged according to the established charging strategy, that is, any temperature and any state of charge are selected, and the battery is charged according to the predetermined charging rate. Collect the potential and charging current of the first electrode at the current charging rate, and determine the voltage drop of the first electrode between any two moments; The charging DC internal resistance of the battery is calculated based on the first voltage drop and charging current of the first electrode between the first and second moments. Based on the second voltage drop of the first electrode at the third moment and the critical lithium plating moment, and the charging DC internal resistance, the critical current at the current temperature and current SOC is calculated. For any battery of the same type, the charging current is controlled to be less than the critical current based on the battery temperature and SOC during charging.

2. The charging method according to claim 1, characterized in that, After calculating the critical current at the current temperature and current SOC, the charging method further includes: Based on the relationship between charging current and charging rate, the critical current is converted into the critical charging rate.

3. The charging method according to claim 1, characterized in that, The first moment is the start of charging, and the second moment is the end of charging.

4. The charging method according to claim 1, characterized in that, The temperature range includes -20℃ to 25℃; the SOC range includes 0% to 95%.

5. The charging method according to claim 4, characterized in that, Each temperature corresponds to multiple SOCs, and each SOC at each temperature corresponds to a charging rate.

6. The charging method according to claim 1, characterized in that, The third moment is the moment when charging begins.

7. The charging method according to claim 1, characterized in that, The battery is a three-electrode lithium-ion battery, wherein the electrodes of the three-electrode lithium-ion battery are a positive electrode, a negative electrode, and a reference electrode.

8. The charging method according to claim 7, characterized in that, The first electrode is the negative electrode of a three-electrode lithium-ion battery.

9. A charging device for a lithium-ion battery, characterized in that, The charging device includes: A storage module is used to store data, including a charging strategy based on the SOC corresponding to different temperatures: the charging strategy includes the charging rate at different SOCs corresponding to each temperature. The pre-charge module is used to charge the battery according to a predetermined charging strategy, that is, to select any temperature and any SOC and charge it according to a predetermined charging rate. The monitoring module is used to collect the potential and charging current of the first electrode at the current charging rate and determine the voltage drop of the first electrode between any two moments. The first calculation module is used to calculate the charging DC internal resistance of the battery based on the first voltage drop and charging current of the first electrode between the first time and the second time. The second calculation module is used to calculate the critical current at the current temperature and current SOC based on the second voltage drop of the first electrode at the third time and the critical lithium plating time and the charging DC internal resistance. The charging module is used to charge any battery of the same type. Based on the battery temperature and SOC during charging, it controls the charging current to be less than the critical current.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of the charging method for a lithium-ion battery as described in any one of claims 1 to 8.

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