Capacity grading and discharging control method and capacity grading equipment of lithium ion battery

Abstract

The invention discloses a capacity grading and discharging control method and capacity grading equipment of a lithium ion battery. The capacity grading and discharging control method comprises the following steps: acquiring a relation curve between open-circuit voltage and charge capacity of a finished battery cell of the lithium ion battery; detecting a first open-circuit voltage of the lithium ion battery, and determining a first charge capacity corresponding to the first open-circuit voltage according to the relation curve; obtaining a preset shipment voltage range, determining a preset discharge capacity according to the shipment voltage range, outputting a discharge instruction according to the discharge capacity, and determining a second open-circuit voltage of the lithium ion battery after the lithium ion battery is discharged according to the discharge capacity; according to the relation curve and the second open-circuit voltage, a second charge capacity is obtained, according to the first charge capacity and the second charge capacity, the variable quantity of the charge capacity is determined, and according to the discharge capacity and the variable quantity of the charge capacity, the actual capacity grading capacity of the lithium ion battery is obtained through calculation. The capacity grading time and the production time of the battery are shortened, and the efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a lithium ion battery capacity division and discharge control method and capacity division equipment. Background Art

[0002] As an important component of modern energy technology, lithium-ion batteries have experienced a leapfrog development from laboratory to commercial application since their introduction in the early 1970s. With their high energy density, long cycle life and environmental protection characteristics, lithium-ion batteries have not only changed our daily lives, but also played a vital role in the global energy transformation.

[0003] The traditional capacity division process is: first charge the battery to full power, measure the full power capacity, then use the specified current to discharge to 3.0V to obtain the battery capacity, and finally charge the battery to the shipping voltage. In this process, the battery production time and capacity division time are long and the efficiency is low. Summary of the invention

[0004] The embodiment of the present invention provides a lithium ion battery capacity division, discharge to shipping voltage method and capacity division equipment to solve the problem of long production and capacity division time and low efficiency of traditional batteries.

[0005] Based on the above purpose, in one embodiment, a method for dividing the capacity of a lithium-ion battery is provided, comprising: Obtaining a relationship curve between the open circuit voltage and the charge of a finished lithium-ion battery cell; Detecting the open circuit voltage of the lithium ion battery to obtain a first open circuit voltage, and determining a first charge corresponding to the first open circuit voltage according to the relationship curve; Acquire a preset shipping voltage range, determine a preset discharge capacity according to the shipping voltage range, output a discharge instruction according to the discharge capacity, and determine a second open circuit voltage of the lithium ion battery after the lithium ion battery is discharged according to the discharge capacity; A second charge is obtained according to the relationship curve and the second open circuit voltage; a change in charge is determined according to the first charge and the second charge; and an actual capacity distribution capacity of the lithium-ion battery is calculated according to the discharge capacity and the change in charge.

[0006] The above-mentioned capacity division method of lithium-ion batteries obtains the relationship curve between the open circuit voltage and the charge of the finished battery cell of the lithium-ion battery, detects the first open circuit voltage of the lithium-ion battery, obtains the corresponding first charge, and then obtains the preset shipping voltage according to the preset shipping voltage range, determines the preset discharge capacity of the lithium-ion battery, performs discharge treatment on the battery to obtain the second open circuit voltage, obtains the second charge according to the second open circuit voltage and the relationship curve, and calculates according to the obtained data to obtain the actual capacity division capacity of the battery. Compared with the traditional method of obtaining the capacity division capacity by charging, discharging and standing the battery, only the discharge operation is performed and the capacity division capacity is obtained by calculation, which saves the capacity division time and improves the efficiency of the capacity division.

[0007] In one embodiment, obtaining a preset delivery voltage range, and determining a preset discharge capacity according to the delivery voltage range includes: According to the delivery voltage range, a preset delivery voltage is calculated, according to the relationship curve, a third charge corresponding to the delivery voltage is obtained, and according to a specified average capacity, the first charge and the third charge, the discharge capacity is determined.

[0008] In one embodiment, the delivery voltage range includes: a first delivery voltage value and a second delivery voltage value, and the calculation expression of the delivery voltage is: , Among them, V1 is the first shipping voltage value, and V2 is the second shipping voltage value.

[0009] In one embodiment, after the lithium-ion battery is discharged according to the preset discharge capacity, determining the second open circuit voltage of the lithium-ion battery includes: After the lithium-ion battery is discharged according to the preset discharge capacity, the instantaneous voltage value of the lithium-ion battery at each moment is measured multiple times within a preset voltage rebound time period, and a voltage-time relationship curve of the lithium-ion battery is obtained by fitting, and a second open circuit voltage of the lithium-ion battery is determined according to the voltage-time relationship curve.

[0010] In one embodiment, according to the change in the discharge capacity and the charge amount, the calculation expression for obtaining the actual capacity distribution capacity of the lithium-ion battery is: , in, is the specified mean capacity, is the first charge, is the second charge, is the third charge amount, is the discharge capacity, is the change in the charge.

[0011] In one embodiment, a discharge control method for a lithium-ion battery is provided, comprising: Obtaining a relationship curve between the open circuit voltage and the charge of a finished lithium-ion battery cell; Detecting the open circuit voltage of the lithium ion battery to obtain a first open circuit voltage, and determining a first charge corresponding to the first open circuit voltage according to the relationship curve; A preset shipping voltage range is obtained, a preset discharge capacity is determined according to the shipping voltage range, a discharge instruction is output according to the discharge capacity, and after the lithium-ion battery is discharged according to the discharge capacity, the lithium-ion battery is discharged to the shipping voltage range.

[0012] The above-mentioned discharge control method of the lithium-ion battery obtains the relationship curve between the open circuit voltage and the charge of the finished battery cell of the lithium-ion battery, detects the first open circuit voltage of the lithium-ion battery, obtains the corresponding first charge, and then obtains the preset shipping voltage according to the preset shipping voltage range, determines the preset discharge capacity, and discharges the battery directly to the shipping voltage. Compared with the traditional battery manufacturing process that needs to go through charging and discharging and then charging to the shipping voltage, it can shorten the battery production time and improve efficiency.

[0013] In one embodiment, a preset shipping voltage range is obtained, and a preset discharge capacity is determined according to the shipping voltage range, including: calculating a preset shipping voltage according to the shipping voltage range, obtaining a third charge corresponding to the shipping voltage according to the relationship curve, and calculating the discharge capacity according to a specified average capacity, the first charge, and the third charge.

[0014] In one embodiment, the delivery voltage range includes: a first delivery voltage value and a second delivery voltage value, and the calculation expression of the delivery voltage is: , Among them, V1 is the first shipping voltage value, and V2 is the second shipping voltage value.

[0015] In one embodiment, the discharge capacity is calculated based on the specified average capacity, the first charge and the third charge as follows: , in, is the specified mean capacity, is the first charge, is the third charge amount.

[0016] In one embodiment, a capacity division device is provided, wherein the capacity division device is used to divide the capacity of a lithium-ion battery by a capacity division method.

[0017] The above-mentioned lithium-ion battery capacity grading equipment can detect batteries with substandard capacity or quality problems by using the capacity grading equipment to grade lithium-ion batteries, ensuring that users obtain high-quality, high-performance products, and further improving the consistency and reliability of batteries. Through capacity grading, batteries with similar performance can be formed into battery packs to extend the life of the battery packs. Through precise detection and discharge processing, lithium-ion batteries can be graded, which improves production efficiency and reduces labor production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0019] Figure 1 is a flow chart of lithium-ion battery capacity division in one embodiment of the present invention; Figure 2 This is a flow chart of discharging a lithium-ion battery to a shipping voltage in one embodiment of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0022] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0023] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0024] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0025] In order to fully understand the present invention, detailed structures and steps will be presented in the following description to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0026] In one embodiment, a method for dividing the capacity of a lithium-ion battery is provided, comprising: S101, obtaining a relationship curve between the open circuit voltage and the charge of a finished lithium-ion battery cell; Among them, when obtaining the relationship curve, the finished battery cell of the same model is first fully charged to 100%, and then the battery is kept in an uninterrupted discharge state with a constant current. Multiple test points are set during the discharge process, and the open circuit voltage of each test point is recorded. Finally, the recorded data is fitted and plotted to obtain a relationship curve between the open circuit voltage and the charge.

[0027] S102, detecting an open circuit voltage of the lithium-ion battery to obtain a first open circuit voltage, and determining a first charge corresponding to the first open circuit voltage according to the relationship curve; When discharging, different discharge rates can be used to ensure the reliability of the curve. When detecting the open circuit voltage of a lithium-ion battery, a voltmeter is used to obtain the first open circuit voltage. The lithium-ion battery detected is after formation treatment. The main purpose of formation is to activate the positive and negative electrode materials in the battery to stabilize its performance, thereby improving the battery's charge and discharge performance, self-discharge characteristics, and storage performance. During the formation process, when lithium ions are inserted into graphite for the first time, an electrochemical reaction will occur in the battery to form a layer of solid electrolyte interface film (SEI film). The formation of the SEI film is crucial to the performance of the battery. It not only consumes some lithium ions, but also affects the battery's electrochemical properties such as cycle life, stability, self-discharge and safety. According to the first open circuit voltage obtained by the test, the corresponding first charge is obtained in the relationship curve.

[0028] S103, obtaining a preset delivery voltage range, determining a preset discharge capacity according to the delivery voltage range, outputting a discharge instruction according to the discharge capacity, and determining a second open circuit voltage of the lithium ion battery after the lithium ion battery is discharged according to the discharge capacity; Among them, the preset shipping voltage range can be obtained through the battery of this model after formation. Through the shipping voltage range, the preset discharge capacity to be discharged for the lithium-ion battery can be determined, and then a discharge instruction is output to discharge the battery. When discharging, there is no requirement for the discharge current. It is necessary to ensure that the discharge capacity is the preset discharge capacity and that the discharge is within the preset shipping voltage range. After the discharge is detected to be completed, the second open circuit voltage of the lithium-ion battery is determined by testing.

[0029] S104, obtaining a second charge according to the relationship curve and the second open circuit voltage, determining a change in charge according to the first charge and the second charge, and calculating an actual capacity distribution capacity of the lithium-ion battery according to the discharge capacity and the change in charge.

[0030] Among them, according to the relationship curve between the second open circuit voltage obtained in S103 and the open circuit voltage and the charge obtained in S101, the corresponding second charge is obtained, and the change of the charge is determined according to the first charge and the second charge. According to the preset discharge capacity and the change of the charge, the actual capacity division capacity of the lithium-ion battery is calculated, and the lithium-ion battery is divided according to the actual capacity division capacity.

[0031] The above-mentioned capacity division method of lithium-ion batteries obtains the relationship curve between the open circuit voltage and the charge of the finished battery cell of the lithium-ion battery, detects the first open circuit voltage of the lithium-ion battery, obtains the corresponding first charge, and then obtains the preset shipping voltage according to the preset shipping voltage range, determines the preset discharge capacity of the lithium-ion battery, performs discharge treatment on the battery to obtain the second open circuit voltage, obtains the second charge according to the second open circuit voltage and the relationship curve, and calculates according to the obtained data to obtain the actual capacity division capacity of the battery. Compared with the traditional method of obtaining the capacity division capacity by charging, discharging and standing the battery, only the discharge operation is performed and the capacity division capacity is obtained by calculation, which saves the capacity division time and improves the efficiency of the capacity division.

[0032] In one embodiment, a preset shipping voltage range is obtained, and a preset discharge capacity is determined according to the shipping voltage range, including: calculating a shipping voltage according to the shipping voltage range, obtaining a third charge corresponding to the shipping voltage according to the relationship curve, and determining the discharge capacity according to a specified average capacity, the first charge, and the third charge.

[0033] Among them, a preset shipping voltage can be obtained according to the preset shipping voltage range, and the third charge corresponding to the preset shipping voltage is obtained from the relationship curve diagram between the obtained open circuit voltage and the charge. The specified mean capacity refers to the average capacity of the battery under standard test conditions, which can reflect the performance stability of the battery in multiple charge and discharge cycles. The preset discharge capacity can be calculated based on the specified mean capacity, the obtained first charge and the third charge.

[0034] In this embodiment, the preset shipping voltage range is obtained through the lithium-ion battery model, and the shipping voltage and its corresponding third charge amount are obtained. The preset discharge capacity can be obtained by calculation. Compared with the traditional detection and calculation that requires charging and then discharging, the process is simpler and can improve the efficiency of the battery capacity division process.

[0035] In one embodiment, the delivery voltage range includes: a first delivery voltage value and a second delivery voltage value, and the calculation expression of the delivery voltage is: , Among them, V1 is the first shipping voltage value, and V2 is the second shipping voltage value.

[0036] Among them, the obtained delivery voltage range V1-V2 has two endpoint values, namely the first delivery voltage value V1 and the second delivery voltage value V2. According to the preset delivery voltage calculation expression The preset shipping voltage is calculated.

[0037] In this embodiment, the preset shipping voltage is calculated based on the two endpoints of the preset shipping voltage range: the first shipping voltage value V1 and the second shipping voltage value V2. The process is simple and easy to implement, which can reduce the difficulty of production, simplify the production process, and improve the efficiency of battery production.

[0038] In one embodiment, after the lithium-ion battery is discharged according to the preset discharge capacity, determining the second open circuit voltage of the lithium-ion battery includes: After the lithium-ion battery is discharged according to the preset discharge capacity, the instantaneous voltage value of the lithium-ion battery at each moment is measured multiple times within a preset voltage rebound time period, and a voltage-time relationship curve of the lithium-ion battery is obtained by fitting, and a second open circuit voltage of the lithium-ion battery is determined according to the voltage-time relationship curve.

[0039] Among them, within the preset voltage rebound time period, the instantaneous voltage value of the lithium-ion battery at each moment is measured multiple times at fixed time intervals and recorded, and the recorded data is fitted to obtain a voltage-time relationship curve of the lithium-ion battery. According to the relationship curve, calculation is performed to obtain a stable voltage value of the lithium-ion battery when time tends to infinity, and the second open circuit voltage of the lithium-ion battery can be determined.

[0040] Optionally, the lithium-ion battery may be placed in a static state to obtain an aged battery, and the aged battery may be measured to obtain the second open circuit voltage.

[0041] In this embodiment, after the lithium-ion battery is discharged according to the preset discharge capacity, the instantaneous voltage of the lithium-ion battery at each moment is measured and recorded multiple times within a preset time period, and fitting is performed based on the obtained data to obtain a curve of the relationship between the voltage and time of the lithium-ion battery, and the second open-circuit voltage of the lithium-ion battery is calculated. Compared with the traditional process, the second open-circuit voltage is obtained by using the curve fitting method, which shortens the time of the battery capacity division process and improves the efficiency.

[0042] In one embodiment, according to the change in the discharge capacity and the charge amount, the calculation expression for obtaining the actual capacity distribution capacity of the lithium-ion battery is: , in, is the specified mean capacity, is the first charge, is the second charge, is the third charge amount, is the discharge capacity, is the change in the charge.

[0043] In this embodiment, the actual capacity division capacity of the battery is calculated according to the calculation expression of the actual capacity division capacity of the lithium-ion battery, and the capacity division is performed, which omits the process of charging and discharging the battery, making the capacity division of the lithium-ion battery simpler, and at the same time can reduce the capacity division time and improve the capacity division efficiency; the preset discharge capacity of the lithium-ion battery is calculated according to the calculation expression, which saves the time of the capacity division process compared with the traditional method of charging and discharging the battery through charge and discharge cycles to obtain the discharge capacity.

[0044] In one embodiment, a discharge control method for a lithium-ion battery is provided, comprising: S601, obtaining a relationship curve between the open circuit voltage and the charge of the finished lithium-ion battery cell; S602, detecting an open circuit voltage of the lithium-ion battery to obtain a first open circuit voltage, and determining a first charge corresponding to the first open circuit voltage according to the relationship curve; Among them, the relationship curve between the open circuit voltage and the charge is obtained, and the corresponding charge can be obtained according to the obtained open circuit voltage, which is convenient for subsequent calculations. The lithium-ion battery is a formed battery, and the corresponding first charge is obtained according to the relationship curve between the open circuit voltage and the charge obtained by the test and the first open circuit voltage.

[0045] S603, obtaining a preset shipping voltage range, determining a preset discharge capacity according to the shipping voltage range, outputting a discharge instruction according to the discharge capacity, and discharging the lithium ion battery to the shipping voltage range after the lithium ion battery is discharged according to the discharge capacity.

[0046] Among them, after determining the preset discharge capacity according to the shipping voltage, the discharge operation is performed. At this time, no restriction is imposed on the discharge current. While ensuring that the discharge capacity is the preset discharge capacity, the open circuit voltage of the battery after discharge is within the shipping voltage range.

[0047] In this embodiment, by obtaining a relationship curve between the open circuit voltage and the charge of the finished battery cell of the lithium-ion battery, detecting the first open circuit voltage of the lithium-ion battery, obtaining the corresponding first charge, and then obtaining the preset shipping voltage according to the preset shipping voltage range, determining the preset discharge capacity, and performing a discharge process on the battery to directly discharge it to the shipping voltage, compared with the traditional battery manufacturing process that needs to go through charging and discharging and then charging to the shipping voltage, the battery production time can be shortened and the efficiency can be improved.

[0048] In one embodiment, a preset shipping voltage range is obtained, and a preset discharge capacity is determined according to the shipping voltage range, including: calculating a preset shipping voltage according to the shipping voltage range, obtaining a third charge corresponding to the shipping voltage according to the relationship curve, and calculating the discharge capacity according to a specified average capacity, the first charge, and the third charge.

[0049] Among them, a shipping voltage can be obtained according to the shipping voltage range, and then the corresponding third charge can be obtained according to the relationship curve between the open circuit voltage and the charge. The specified average capacity is obtained according to the battery model, and the preset discharge capacity is calculated according to the first charge and the third charge obtained previously.

[0050] In this embodiment, the preset discharge capacity is obtained by calculation. Compared with the traditional method of first fully charging the battery and then discharging it with a specific current to obtain the discharge capacity, the discharge capacity is directly calculated, which makes the battery production process simpler and faster, shortens the production time, and improves production efficiency.

[0051] In one embodiment, the preset delivery voltage range includes: a first delivery voltage value and a second delivery voltage value, and the calculation expression of the preset delivery voltage is: , Among them, V1 is the first shipping voltage value, and V2 is the second shipping voltage value.

[0052] In this embodiment, the preset shipping voltage is calculated through the two end values ​​of the preset shipping voltage range V1-V2: the first shipping voltage value V1 and the second shipping voltage value V2. The process is simple and easy to implement, which can reduce the difficulty of production, simplify the production process, and improve the efficiency of battery production.

[0053] In one embodiment, the calculation expression for obtaining the preset discharge capacity according to the prescribed average capacity, the first charge amount and the third charge amount is: , in, is the specified mean capacity, is the first charge, is the third charge amount.

[0054] In this embodiment, the discharge capacity of the lithium-ion battery is obtained by calculation. Compared with the traditional method of obtaining the discharge capacity by fully charging the battery and then discharging it with a specified current, the discharge capacity is obtained by directly calculating the discharge capacity, which saves time and improves efficiency.

[0055] In one embodiment, a capacity division device is provided, wherein the capacity division device is used to divide the capacity of a lithium-ion battery by a capacity division method.

[0056] In this embodiment, the capacity division device is used to divide the capacity of lithium-ion batteries, which can detect batteries that do not meet the capacity standards or have quality problems, ensuring that users obtain high-quality, high-performance products, and further improving the consistency and reliability of batteries. Through capacity division, batteries with similar performance are formed into battery packs to extend the life of the battery packs. Through precise detection and discharge processing, the capacity of lithium-ion batteries is divided, which improves production efficiency and reduces labor production costs.

[0057] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for dividing the capacity of a lithium-ion battery, characterized in that: include: Obtaining a relationship curve between the open circuit voltage and the charge of a finished lithium-ion battery cell; Detecting the open circuit voltage of the lithium ion battery to obtain a first open circuit voltage, and determining a first charge corresponding to the first open circuit voltage according to the relationship curve; Acquire a preset shipping voltage range, determine a preset discharge capacity according to the shipping voltage range, output a discharge instruction according to the discharge capacity, and determine a second open circuit voltage of the lithium ion battery after the lithium ion battery is discharged according to the discharge capacity; Obtaining a second charge according to the relationship curve and the second open circuit voltage; The change in charge is determined according to the first charge and the second charge, and the actual capacity distribution capacity of the lithium-ion battery is calculated according to the discharge capacity and the change in charge.

2. The capacity division method according to claim 1, characterized in that: Obtaining a preset delivery voltage range, and determining a preset discharge capacity according to the delivery voltage range, including: According to the delivery voltage range, a preset delivery voltage is calculated, according to the relationship curve, a third charge corresponding to the delivery voltage is obtained, and according to a specified average capacity, the first charge and the third charge, the discharge capacity is determined.

3. The capacity division method according to claim 2, characterized in that: The delivery voltage range includes: a first delivery voltage value and a second delivery voltage value, and the calculation expression of the delivery voltage is: ， Among them, V1 is the first shipping voltage value, and V2 is the second shipping voltage value.

4. The capacity division method according to claim 1, characterized in that: After the lithium-ion battery is discharged according to the preset discharge capacity, determining a second open circuit voltage of the lithium-ion battery includes: After the lithium-ion battery is discharged according to the capacity to be discharged, within a preset voltage rebound time period, the instantaneous voltage value of the lithium-ion battery at each moment is measured multiple times, and a voltage-time relationship curve of the lithium-ion battery is obtained by fitting, and a second open circuit voltage of the lithium-ion battery is determined according to the voltage-time relationship curve.

5. The capacity division method according to claim 2, characterized in that: According to the change in the discharge capacity and the charge amount, the actual capacity of the lithium-ion battery is calculated as follows: ， in, is the specified mean capacity, is the first charge, is the second charge, is the third charge amount, is the discharge capacity, is the change in the charge.

6. A discharge control method for a lithium-ion battery, characterized in that: include: Obtain the relationship curve between the open circuit voltage and the charge of the finished lithium-ion battery cell; Detecting the open circuit voltage of the lithium ion battery to obtain a first open circuit voltage, and determining a first charge corresponding to the first open circuit voltage according to the relationship curve; A preset shipping voltage range is obtained, a preset discharge capacity is determined according to the shipping voltage range, a discharge instruction is output according to the discharge capacity, and after the lithium-ion battery is discharged according to the discharge capacity, the lithium-ion battery is discharged to the shipping voltage range.

7. The discharge control method according to claim 6, characterized in that: Obtaining a preset shipping voltage range, and determining a preset discharge capacity according to the shipping voltage range, including: calculating a preset shipping voltage according to the shipping voltage range, obtaining a third charge corresponding to the shipping voltage according to the relationship curve, and calculating the discharge capacity according to a specified average capacity, the first charge, and the third charge.

8. The discharge control method according to claim 7, characterized in that: The delivery voltage range includes: a first delivery voltage value and a second delivery voltage value, and the calculation expression of the delivery voltage is: ， Among them, V1 is the first shipping voltage value, and V2 is the second shipping voltage value.

9. The discharge control method according to claim 7, characterized in that: The calculation expression for the discharge capacity is calculated based on the specified average capacity, the first charge and the third charge: ， in, is the specified mean capacity, is the first charge, is the third charge amount.

10. A capacity division device, characterized in that: The capacity division device is used for performing capacity division according to the capacity division method as claimed in any one of claims 1 to 5.

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