Battery cell formation method, battery cell, electronic equipment and computer program product

Abstract

The invention is suitable for the field of battery cell manufacturing, and provides a battery cell formation method, a battery cell, electronic equipment and a computer program product.The method comprises the steps that at a first set temperature, a first set current is adopted to charge a liquid-injected battery cell till the charging voltage reaches a first cut-off voltage; the first set temperature is less than or equal to a preset temperature, and the first set current is less than or equal to a preset current; completely discharging the liquid-injected battery cell of which the charging voltage reaches the first cut-off voltage; and returning to execute the step of charging the liquid-injected battery cell by adopting the first set current at the first set temperature until the charging voltage reaches the first cut-off voltage, and when the charging times reach the preset charging times, obtaining a target battery cell of which the SEI film compactness meets the requirement. According to the scheme, the SEI film compactness of the battery cell can be improved, and the cycle performance of the battery cell is improved.

Description

Technical Field

[0001] The present application belongs to the field of battery cell manufacturing, and in particular to a battery cell formation method, a battery cell, an electronic device and a computer program product. Background Art

[0002] The long cycle performance of a battery cell refers to the ability of the battery cell to withstand long-term and multiple cycles during the charging and discharging process without significantly reducing its performance. The cycle performance of a battery cell is related to the density of the solid electrolyte interface membrane (SEI membrane) formed during the formation of the battery cell.

[0003] At present, the existing technology uses a small current formation method for formation. Under a small current, the formation time increases and the probability of side reactions also increases. The side reactions not only affect the chemical composition of the SEI film, but also destroy the SEI film. The density of the SEI film in the battery cell formed in this way is poor, which affects the cycle performance of the battery cell. Summary of the invention

[0004] The embodiments of the present application provide a battery cell formation method, a battery cell, an electronic device and a computer program product to solve the problem that the SEI film in the battery cell formed by the existing formation method has poor density, which affects the cycle performance of the battery cell.

[0005] A first aspect of an embodiment of the present application provides a battery cell formation method, comprising:

[0006] At a first set temperature, the filled battery cell is charged with a first set current until the charging voltage reaches a first cut-off voltage; the first set temperature is less than or equal to a preset temperature, and the first set current is less than or equal to a preset current;

[0007] Completely discharging the liquid-filled battery cell whose charging voltage reaches the first cut-off voltage;

[0008] Return to the step of charging the liquid-filled battery cell at the first set temperature with the first set current until the charging voltage reaches the first cut-off voltage, and when the number of charging times reaches the preset number of charging times, a target battery cell with SEI film density meeting the requirements is obtained.

[0009] A second aspect of an embodiment of the present application provides a battery cell, which is manufactured based on the steps of the method described in the first aspect.

[0010] A third aspect of an embodiment of the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in the first aspect when executing the computer program.

[0011] A fourth aspect of the embodiments of the present application provides a computer program product. When the computer program product is run on a terminal, the terminal executes the steps of the method described in the first aspect.

[0012] A fifth aspect of an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method described in the first aspect are implemented.

[0013] As can be seen from the above, the present application uses a relatively low temperature, i.e., the first set temperature, and a relatively small current, i.e., the first set current, to charge the liquid-filled battery cell. The low temperature reduces the ion activity and migration speed, slows down the occurrence of side reactions, and reduces the probability of side reactions, effectively avoiding the obstruction of the formation of the SEI film and the damage to its structure by side reactions. At the same time, through cyclic charge and discharge, the probability of film formation is increased, and the formation of the SEI film is promoted together, and the compactness of the SEI film inside the battery cell is improved. In summary, the present application successfully forms a dense SEI film inside the battery cell by strictly controlling the temperature, current, and charging method, thereby improving the cycle performance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 This is a process of a battery cell formation method provided in an embodiment of the present application Figure 1 ;

[0016] Figure 2 This is a process of a battery cell formation method provided in an embodiment of the present application Figure 2 ;

[0017] Figure 3 This is a comparison diagram of the cycle effects of target finished battery cells formed under different formation scenarios provided in an embodiment of the present application;

[0018] Figure 4 It is a structural diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0020] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0021] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0022] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0023] As used in this specification and the appended claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" may be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0024] In a specific implementation, the terminal described in the embodiments of the present application includes, but is not limited to, other portable devices such as mobile phones, laptop computers, or tablet computers with touch-sensitive surfaces (e.g., touch screen displays and / or touch pads). It should also be understood that in some embodiments, the device is not a portable communication device, but a desktop computer with a touch-sensitive surface (e.g., touch screen displays and / or touch pads).

[0025] In the following discussion, a terminal including a display and a touch-sensitive surface is described. However, it should be understood that the terminal may include one or more other physical user interface devices such as a physical keyboard, mouse and / or joystick.

[0026] The terminal supports various applications, such as one or more of the following: a drawing application, a presentation application, a word processing application, a website creation application, a disk burning application, a spreadsheet application, a game application, a telephone application, a video conferencing application, an email application, an instant messaging application, a workout support application, a photo management application, a digital camera application, a digital camcorder application, a web browsing application, a digital music player application, and / or a digital video player application.

[0027] Various applications that can be executed on the terminal can use at least one common physical user interface device such as a touch-sensitive surface. One or more functions of the touch-sensitive surface and corresponding information displayed on the terminal can be adjusted and / or changed between applications and / or within corresponding applications. In this way, the common physical architecture of the terminal (e.g., the touch-sensitive surface) can support various applications with user interfaces that are intuitive and transparent to the user.

[0028] It should be understood that the size of the serial numbers of the steps in this embodiment does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0029] In order to illustrate the technical solution described in this application, a specific embodiment is provided below for illustration.

[0030] See also Figure 1 , Figure 1 This is a process of a battery cell formation method provided in an embodiment of the present application Figure 1 .like Figure 1 As shown, a battery cell formation method comprises the following steps:

[0031] Step 101, charging the filled battery cell with a first set current at a first set temperature until the charging voltage reaches a first cut-off voltage; the first set temperature is less than or equal to a preset temperature, and the first set current is less than or equal to a preset current.

[0032] In some embodiments, the liquid-filled battery cell is a battery cell that has been left standing after liquid injection. Therefore, the liquid-filled battery cell is charged at a first set temperature using a first set current until the charging voltage reaches a first cut-off voltage, and also includes: leaving the semi-finished battery cell after liquid injection standing for a preset period of time to obtain the liquid-filled battery cell.

[0033] It is necessary to inject electrolyte into the semi-finished battery cell that has not been injected, and obtain the semi-finished battery cell after injection. After injection, it is left to stand for a period of time to ensure that the electrolyte can fully penetrate into it, improve the uniformity of electrolyte distribution, and ensure that the internal wetting interface of the electrode is good. The uniform electrolyte distribution is very helpful for the formation of a uniform and stable SEI film during the formation process. At the same time, standing after injection can also avoid problems such as local overheating and gas production of the battery cell during the charging and discharging process due to insufficient penetration or uneven distribution of the electrolyte, and improve the performance indicators of the battery cell such as capacity, cycle life and charging and discharging efficiency, that is, improve the safety and stability of the battery cell.

[0034] The preset time is determined according to factors such as the properties of the electrolyte, the internal structure of the battery cell, and the amount of liquid injected, and the semi-finished battery cell is left to stand for the preset time to obtain the liquid-injected battery cell.

[0035] In some embodiments, the preset time length is 4-8 hours, or the preset time length is 24-48 hours.

[0036] After the rest period is completed, the battery cell formation stage officially begins. Battery cell formation is a very important part of the battery cell production process. It is the process of charging the battery cell for the first time after liquid injection.

[0037] For batteries, such as lithium-containing batteries, formation can activate the active substances in the battery and activate the battery. When charging, the lithium salt reacts with the electrolyte, and at the same time, a SEI film is formed on the negative electrode surface of the battery. The SEI film can prevent the side reaction from further occurring, thereby reducing the loss of active lithium in the battery, avoiding the damage of solvent molecules to the electrode material, and ensuring the cycle performance of the battery.

[0038] Before formation, the temperature, current, cut-off voltage, pressure and other data required for formation are preset.

[0039] In some embodiments, the pressure value may be selected within the range of 1-2 MPa.

[0040] In some embodiments, the preset temperature is 10° C. When the temperature is lower than 0° C., lithium deposition may occur in the battery cell. Therefore, the first set temperature is usually set within the temperature range of 0-10° C.

[0041] In some embodiments, the preset current is a current value corresponding to 0.2C, where C is the rated capacity of the battery cell. Accordingly, the value range of the first set current is a current value range corresponding to 0-0.2C, and the first set current is not 0.

[0042] During the formation period of the SEI film, a smaller current is required to form a denser SEI film.

[0043] The first cut-off voltage is determined according to the formation requirements of the SEI film. The cut-off voltage is represented by the battery state of charge (SOC).

[0044] In some embodiments, the value range of the first cut-off voltage is a voltage value range corresponding to 4%-6% SOC.

[0045] At the first set temperature, the activity of the electrolyte in the battery cell is reduced, that is, under this temperature environment, the ion activity is low, the migration speed is slow, and the side reaction rate is reduced. Correspondingly, the probability of side reactions is reduced, and the side reactions that hinder the formation of the SEI film and destroy the structure of the SEI film are avoided as much as possible, which helps to form a more uniform, dense and stable SEI film. In addition, low-temperature formation can reduce gas production and improve the consistency of the battery cell interface.

[0046] When charging the battery cell with a smaller first set current, a single electron reaction is more likely to occur inside the battery cell, which reduces the amount of impurities generated during the formation of the SEI film, thereby forming a purer and denser SEI film. At the same time, charging with a small current can reduce the internal polarization phenomenon, so that the ions in the electrolyte are more evenly distributed on the electrode surface, reducing the unevenness and defects of the SEI film during the formation process, and helping to form a more uniform and dense SEI film. In addition, using a smaller charging current can also reduce the heat generated internally during charging, further reduce the thermal stress of the SEI film during the formation process, and improve the quality and stability of the SEI film.

[0047] The combination of low temperature and small current solves the problem of long-term formation with small current, which increases the probability of side reactions, affects the formation of SEI film and destroys the SEI film. It retains the film-forming advantages of small current, that is, compared with large current, the SEI film formed by small current has better density and uniform film formation.

[0048] When the charging voltage reaches the first cut-off voltage, it means that the SEI film in the battery cell is basically formed. Compared with the existing formation method, the density has been improved at this time.

[0049] Step 102: Completely discharge the liquid-filled battery cell whose charging voltage reaches the first cut-off voltage.

[0050] In order to further improve the compactness, the battery cell is charged and discharged in a cycle. In order for the cyclic charge and discharge to proceed in an orderly manner, the battery cell needs to be fully discharged to ensure that the next charge can be carried out.

[0051] In some embodiments, during full discharge, the battery is discharged at a first set current under a first temperature environment. The object of full discharge is a battery cell whose charging voltage reaches a first cut-off voltage.

[0052] Step 103, when the number of charging times reaches a preset number of charging times, a target battery cell having SEI film density meeting the requirements is obtained.

[0053] After each charge and discharge, it is determined whether the number of charge times reaches the preset number of charge times.

[0054] The number of charging times refers to the number of times the battery cell is charged at the first set temperature and the first set current so that the charging voltage of the battery cell reaches the first cut-off voltage.

[0055] The preset charging times are pre-set times for charging the battery cell at the first set temperature and the first set current, and for making the charging voltage of the battery cell reach the first cut-off voltage.

[0056] If the charging times are less than the preset charging times, step 102 is executed to fully discharge. At this time, the charging times are still less than the preset charging times. After fully discharging, the above step 101 is returned to be executed. The battery cell is charged again at the first set temperature and the first set current until the charging voltage reaches the first cut-off voltage.

[0057] In some embodiments, after each charging is completed, it is determined whether the number of charging times reaches the preset number of charging times. If the number of charging times is equal to the preset number of charging times, the cyclic charging and discharging operation is stopped, and the subsequent full discharge operation is not performed to obtain a target battery cell with SEI film density that meets the requirements and a charging voltage of the first cut-off voltage, or a subsequent full discharge operation is performed to obtain a target battery cell with SEI film density that meets the requirements. At this time, the SEI film has a compactness of particles or molecules arranged tightly, the SEI film has a blocking ability to external substances, and has stability and durability during the charging and discharging process. All meet the set requirements.

[0058] During the entire charge and discharge cycle, the formation environment is maintained at the first set temperature. On the one hand, a constant temperature environment helps to stabilize the chemical reaction inside the battery cell, thereby improving the charging efficiency, reducing the energy loss and thermal stress caused by temperature switching, avoiding battery cell aging and damage, and extending the service life of the battery cell. On the other hand, not performing too many temperature switches can simplify the operating process, while also reducing the burden on the electronic components and circuits of the charging equipment, reducing the wear of the charging equipment, and extending the service life of the charging equipment. In addition, reducing the number of temperature switching times can reduce potential safety hazards such as battery overheating, expansion, and even explosion, thereby improving the safety of the charging process.

[0059] In some embodiments, the preset number of charging times is 3-5 times. If cost is not considered, the preset number of charging times can be further increased.

[0060] This cyclic charge and discharge increases the probability of SEI film formation and can form a denser SEI film, preventing the SEI film from being damaged in the later stage and causing deterioration in battery cell performance.

[0061] In the embodiment of the present application, a relatively low temperature, i.e., the first set temperature, and a relatively small current, i.e., the first set current, are used to charge the liquid-filled battery cell. The low temperature reduces the ion activity and migration speed, slows down the occurrence of side reactions, and reduces the probability of side reactions, effectively avoiding the obstruction of the formation of the SEI film and the damage to its structure by side reactions. At the same time, through cyclic charge and discharge, the probability of film formation is increased, and the formation of the SEI film is promoted together, and the compactness of the SEI film inside the battery cell is improved. In summary, the present application successfully forms a dense SEI film inside the battery cell by strictly controlling the temperature, current, and charging method, thereby improving the cycle performance of the battery cell.

[0062] See also Figure 2 , Figure 2 This is a process of a battery cell formation method provided in an embodiment of the present application Figure 2 .like Figure 2 As shown, a battery cell formation method comprises the following steps:

[0063] Step 201, at a first set temperature, charging the filled battery cell with a first set current until the charging voltage reaches a first cut-off voltage; the first set temperature is less than or equal to a preset temperature, and the first set current is less than or equal to a preset current.

[0064] The implementation process of this step is the same as the implementation process of step 101 in the aforementioned embodiment, and will not be repeated here.

[0065] Step 202: Completely discharge the liquid-filled battery cell whose charging voltage reaches the first cut-off voltage.

[0066] The implementation process of this step is the same as the implementation process of step 102 in the aforementioned embodiment, and will not be repeated here.

[0067] Step 203, when the charging times reach the preset charging times, a target battery cell having SEI film density meeting the requirements is obtained.

[0068] The implementation process of this step is the same as the implementation process of step 103 in the aforementioned embodiment, and will not be repeated here.

[0069] Step 204 , charging the target battery cell with a second set temperature and a second set current until the charging voltage reaches a second cut-off voltage; the second set current is greater than the first set current, and the second cut-off voltage is greater than the first cut-off voltage.

[0070] The above steps 101 to 103, i.e., steps 201 to 203, are determined as the first charging stage. In the first charging stage, cyclic charging and discharging are performed at low temperature and low current, which is the main formation period of the SEI film. After this, the second charging stage and the third charging stage are included, which belong to the formation and perfection stage.

[0071] The second charging stage and the third charging stage can be formed using the pressure value of the first charging stage.

[0072] In the second charging stage, the target battery cell is charged at a second set temperature and a second set current until the charging voltage reaches a second cut-off voltage.

[0073] Entering the second charging stage, the SEI film is basically fully formed and relatively stable, and there is no need to place too many restrictions on the formation temperature and formation current.

[0074] In some embodiments, the second set temperature may be equal to the first set temperature. There is no need to perform temperature switching, and the corresponding technical effects are not described in detail here.

[0075] In some embodiments, the second set temperature is room temperature. In most regions, room temperature is roughly between 18-26°C. Generally, the default room temperature is 25°C. Directly using room temperature as the formation temperature can reduce energy supply. At the same time, compared with the low temperature of the first stage, using a higher temperature can speed up the formation speed of the second charging stage.

[0076] It should be noted that in the second and third charging stages, if the indoor temperature is below 0°C, the formation temperature needs to be increased to ensure stable cell formation.

[0077] In some embodiments, the second set temperature is another temperature higher than room temperature, such as 45° C. Similarly, compared with the low temperature of the first charging stage and the room temperature, this temperature can accelerate the formation speed of the second charging stage.

[0078] In some embodiments, the second set current is greater than the first set current, for example, the second set current is a current value corresponding to 0.2C. This setting can speed up the formation speed of the second charging stage, save time, and improve efficiency. Of course, the second set current should not be too large, otherwise the SEI film is easily damaged.

[0079] In some embodiments, the second cut-off voltage is a cut-off voltage determined based on the stability of the SEI film.

[0080] In some embodiments, the second cut-off voltage has a value range of a voltage value corresponding to 8%-12% SOC.

[0081] The second cut-off voltage is the voltage value corresponding to the sum of the actual charging power in the first charging stage and the charging power in the second charging stage. For example, if the actual charging power in the first charging stage is 5% SOC and the charging power in the second charging stage is 5% SOC, the second cut-off voltage is the voltage value corresponding to 10% SOC.

[0082] In the second charging stage, by continuing to charge, the structure and properties of the SEI film can be further optimized, making it more stable and dense, which helps to improve the cycle life and safety performance of the battery cell. As the battery cell is charged, the active substances inside the battery cell will be further activated. The increase in charging voltage also means that more load ions, such as lithium ions, will be embedded in the negative electrode material, thereby increasing the capacity and performance of the battery cell.

[0083] Step 205 , charging the target battery cell with a third set temperature and a third set current until the charging voltage reaches a third cut-off voltage; the third set current is greater than the first set current, and the third cut-off voltage is greater than the second cut-off voltage.

[0084] In the third charging stage, the battery cell is charged at a third set temperature and a third set current until the charging voltage reaches a third cut-off voltage, so as to deeply activate the active substances inside the battery cell, ensuring that the active materials in the battery cell can fully participate in the subsequent charging and discharging process, thereby improving the capacity and energy density of the finished battery cell.

[0085] The third charging stage also does not impose too many restrictions on the formation temperature and formation current.

[0086] In some embodiments, the third set temperature may be equal to the first set temperature. There is no need to perform temperature switching, and the corresponding technical effects are not described in detail here.

[0087] In some embodiments, the third set temperature is room temperature. Using room temperature as the formation temperature can reduce energy supply, and at the same time, compared with the low temperature of the first charging stage, using a higher temperature can speed up the formation speed of the third charging stage.

[0088] In some embodiments, the third set temperature may also be another temperature higher than room temperature, such as 45° C. Similarly, compared with the low temperature of the first charging stage and the room temperature, this temperature can accelerate the formation speed of the third charging stage.

[0089] In some embodiments, when entering the third charging stage, the SEI film is fully formed and can be charged with a large current. The third set current is greater than the first set current. The third set current can also be greater than the second set current. For example, the third set current is the current value corresponding to 0.5C, which speeds up the formation speed in the third charging stage, saves time and improves efficiency.

[0090] In some embodiments, the third cut-off voltage is a cut-off voltage determined based on user requirements for the capacity of the battery cell, etc.

[0091] In some embodiments, the third cut-off voltage has a value range of a voltage value corresponding to 38%-52% SOC.

[0092] The third cut-off voltage is the voltage value corresponding to the sum of the actual charging power in the first charging stage, the charging power in the second charging stage, and the charging power in the third charging stage. For example, if the actual charging power in the first charging stage is 5% SOC, the charging power in the second charging stage is 5% SOC, and the charging power in the third charging stage is 40% SOC, then the third cut-off voltage is the voltage value corresponding to 50% SOC.

[0093] In the third charging stage, as the charging voltage increases, more active substances inside the battery cell are further activated, allowing it to reach the optimal charging and discharging state, ensuring that the battery cell reaches its designed capacity and performance requirements, stabilizing the structure and performance of the battery cell, and reducing performance degradation and safety risks in subsequent use of the battery cell.

[0094] The present application divides the charging into multiple stages, accurately controls the parameters of each charging stage, and sets appropriate cut-off voltage and formation conditions in each stage, which can not only improve the formation efficiency, but also reduce the safety risks such as overheating and short circuit in the formation process.

[0095] Step 206: encapsulate the target battery cell to obtain a target finished battery cell.

[0096] Finally, the target battery cell that has been charged and processed in three charging stages is packaged to obtain the target finished battery cell.

[0097] Afterwards, users can divide the target finished battery cells into different capacities according to their needs and select the required battery cells.

[0098] The compactness of the SEI film of the target finished battery cell obtained by the battery cell formation method described in the present application is greatly improved, and accordingly, the cycle performance is also greatly improved. The following is proved by specific examples and data.

[0099] The 2Ah soft-pack battery cell is made of a ternary positive electrode material and a graphite negative electrode system through a stacking method. Its operating voltage is stable between 3.00-4.20V and is used as an example battery cell.

[0100] In the first charging stage, the first set temperature and the first set current are charged to the first cut-off voltage, that is, 3.30-3.40V, which is the voltage value corresponding to 5% SOC, and the cycle voltage interval is 2.50V-first cut-off voltage; in the second charging stage, the current value corresponding to the second set temperature and the second set current 0.2C is charged to the second cut-off voltage, that is, 3.60-3.65V, which is the voltage value corresponding to 10% SOC; in the third charging stage, the current value corresponding to the third set temperature and the third set current 0.5C is charged to the third cut-off voltage, that is, 3.85-3.90V, which is the voltage value corresponding to 40% SOC; the pressure of the three charging stages is 1MPa, and the formation temperature of the second charging stage and the third charging stage is 25°C. As shown in Table 1, Table 1 is a schematic table of formation conditions for each charging stage provided by the present application.

[0101] Table 1 Schematic diagram of formation conditions at each charging stage

[0102]

[0103] Table 1 clearly shows the formation conditions of each charging stage. The cut-off voltage has been defined in the previous text and is no longer shown in the table. Based on different formation conditions, different schemes are formed accordingly, namely, comparative example 1, comparative example 2, comparative example 3, embodiment 1, embodiment 2, embodiment 3 and embodiment 4 are formed.

[0104] Based on the above-mentioned formation conditions, the target finished battery cells corresponding to different formation scenarios are obtained by packaging.

[0105] Electrochemical impedance spectroscopy (EIS) analysis was performed on the target finished battery cells formed under different formation scenarios to obtain the SEI membrane impedance of each target finished battery cell. SEI Refers to. SEI It is an important parameter to characterize the performance of the battery. SEI It is positively correlated with the density of the SEI film.

[0106] As shown in Table 2, Table 2 is the R of the target finished battery cells formed under different formation scenarios provided by this application. SEI Schematic table.

[0107] Table 2 R of target finished battery cells formed under different formation scenarios SEI Schematic table

[0108] plan <![CDATA[R SEI ]]> Comparative Example 1 2.57 Comparative Example 2 2.67 Comparative Example 3 2.43 Embodiment 1 2.85 Embodiment 2 2.72 Embodiment 3 2.74 Embodiment 4 2.69

[0109] Based on Table 2, it can be seen that compared with other comparative examples and embodiments, R SEILarger means that the density of its SEI film is higher. According to the data given in Table 1, in the first charging stage, Example 1 adopts the lowest formation temperature, the smallest formation current and the cycle charging number of 3 times for formation, which just proves that the battery cell formation method described in this application can improve the density of the SEI film, that is, it can improve the cycle performance of the target finished battery cell. By comparing this R of Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 2, Example 3 and Example 4 SEI By comparing the data, it can also be seen that low temperature, small current and cyclic charging are very helpful in improving the density of SEI film.

[0110] The following is proved by the measured cycle performance. As shown in Table 3, Table 3 is a schematic table of the capacity retention rate of the target finished battery cells formed under different formation scenarios provided by this application. Among them, the 90-cycle capacity retention rate refers to the percentage of the actual capacity to the initial capacity after the target finished battery cell undergoes 90 charge and discharge cycles. When testing, 1C / 1C charge and discharge cycles are performed at room temperature, and the voltage range is set to 3.00-4.20V.

[0111] Table 3 Schematic diagram of the capacity retention rate of the target finished battery cells formed under different formation scenarios

[0112] plan 90-cycle capacity retention rate Comparative Example 1 97.26％ Comparative Example 2 97.37％ Comparative Example 3 97.13％ Embodiment 1 97.95％ Embodiment 2 97.71％ Embodiment 3 97.80％ Embodiment 4 97.38％

[0113] The capacity retention rate of the target finished battery cell is the cycle performance. Under the same cycle conditions, the higher the capacity retention rate, the better the cycle performance.

[0114] In the data given in Table 3, the target finished battery cell corresponding to the solution of Example 1 has the highest 90-cycle capacity retention rate, that is, the cycle performance under this formation scenario is the best. Similarly, by comparing the data of the 90-cycle capacity retention rate of Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 2, Example 3 and Example 4, it can also be seen that low temperature, small current and cyclic charging can improve the cycle performance of the target finished battery cell.

[0115] like Figure 3 As shown, Figure 3 This is a comparison chart of the cycle effects of a target finished battery cell formed under different formation scenarios provided in an embodiment of the present application.

[0116] Figure 3 The capacity retention of Comparative Example 2, Example 1, Example 2, Example 3 and Example 4 at different cycle periods is intuitively shown in the form of a line graph, that is, the cycle performance at different cycle periods is shown. The test conditions are 1C / 1C charge and discharge cycle at room temperature, and the voltage range is set to 3.00-4.20V.

[0117] based on Figure 3 It can be seen that with the increase of the number of charge and discharge cycles, the capacity of the target finished battery cells of all experimental groups showed a downward trend. Under the same number of cycles, the capacity of the target finished battery cell corresponding to Comparative Example 2 decreased most significantly, while the capacity of the target finished battery cell corresponding to Example 1 remained relatively good.

[0118] Among the five experimental groups of Comparative Example 2, Example 1, Example 2, Example 3 and Example 4, the capacity decline trend of the target finished battery cell corresponding to the solution of Example 1 is the slowest, and its capacity retention rate is the highest, that is, the cycle performance under this formation scenario is the best. It also confirms that the cycle performance of the battery cell can be improved based on low temperature, small current and cyclic charging, that is, the battery cell formation method provided in this application can improve the cycle performance of the battery cell.

[0119] The SEI film of the battery cell obtained based on the battery cell formation method described in the present application is more dense, which improves the ability of the battery cell to resist the destruction of the SEI film during the cycle process, improves the cycle performance of the battery cell, and can provide long-cycle batteries with excellent cycle performance for the energy storage end and the user end.

[0120] In an embodiment of the present application, after the liquid-filled battery cell is charged using the first set temperature and the first set current to obtain a target battery cell with improved SEI film density, the temperature and current are adjusted, and the target battery cell is continued to be charged in stages at a higher temperature and a larger current to accelerate the formation speed, achieve perfect battery cell formation, and finally package to obtain the target finished battery cell that can enter the next process link and has good density.

[0121] An embodiment of the present application provides a battery cell, which is manufactured based on the above-mentioned battery cell formation method. The SEI film of the battery cell has high density and good cycle performance.

[0122] Figure 4 4 is a structural diagram of an electronic device provided in an embodiment of the present application. As shown in the figure, the electronic device 4 of the embodiment includes: at least one processor 40 ( Figure 4 Only one is shown in the figure), a memory 41, and a computer program 42 stored in the memory 41 and executable on the at least one processor 40, wherein the processor 40 implements the steps of any of the above-mentioned method embodiments when executing the computer program 42.

[0123] The electronic device 4 may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The electronic device 4 may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will appreciate that Figure 4It is only an example of the electronic device 4 and does not constitute a limitation of the electronic device 4. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device may also include input and output devices, network access devices, buses, etc.

[0124] The processor 40 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0125] The memory 41 may be an internal storage unit of the electronic device 4, such as a hard disk or memory of the electronic device 4. The memory 41 may also be an external storage device of the electronic device 4, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 4. Further, the memory 41 may also include both an internal storage unit and an external storage device of the electronic device 4. The memory 41 is used to store the computer program and other programs and data required by the electronic device. The memory 41 may also be used to temporarily store data that has been output or is to be output.

[0126] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0127] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0128] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0129] In the embodiments provided in the present application, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are merely schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0130] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0131] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0132] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable 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, computer-readable media do not include electric carrier signals and telecommunication signals.

[0133] The present application implements all or part of the processes in the above-mentioned embodiment method, and may also be implemented through a computer program product. When the computer program product runs on an electronic device, the electronic device can implement the steps in the above-mentioned method embodiments when executing the computer program product.

[0134] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person 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 application, and should all be included in the protection scope of the present application.

Claims

1. A battery cell formation method, characterized in that: include: At a first set temperature, charging the filled battery cell with a first set current until the charging voltage reaches a first cut-off voltage; The first set temperature is less than or equal to a preset temperature, and the first set current is less than or equal to a preset current; Completely discharging the liquid-filled battery cell whose charging voltage reaches the first cut-off voltage; Return to the step of charging the liquid-filled battery cell at the first set temperature with the first set current until the charging voltage reaches the first cut-off voltage, and when the number of charging times reaches the preset number of charging times, a target battery cell with SEI film density meeting the requirements is obtained.

2. The method according to claim 1, characterized in that The method of charging the liquid-filled battery cell at the first set temperature with the first set current until the charging voltage reaches the first cut-off voltage also includes: The semi-finished battery cell after liquid injection is left to stand for a preset period of time to obtain the liquid-injected battery cell.

3. The method according to claim 1, characterized in that The method further comprises: The target battery cell is charged using a second set temperature and a second set current until the charging voltage reaches a second cut-off voltage; the second set current is greater than the first set current, and the second cut-off voltage is greater than the first cut-off voltage; The target battery cell is charged using a third set temperature and a third set current until the charging voltage reaches a third cut-off voltage; the third set current is greater than the first set current, and the third cut-off voltage is greater than the second cut-off voltage; The target battery cell is packaged to obtain a target finished battery cell.

4. The method according to claim 1, characterized in that: The preset charging times is 3-5 times.

5. The method according to claim 3, characterized in that: The preset temperature is 10° C., the second set temperature is room temperature, and / or the third set temperature is room temperature.

6. The method according to any one of claims 1 to 3, characterized in that: The preset current is the current value corresponding to 0.2C.

7. The method according to any one of claims 1 to 3, characterized in that: The first cut-off voltage has a value range of 4%-6% SOC corresponding to the voltage value range, the second cut-off voltage has a value range of 8%-12% SOC corresponding to the voltage value range, and / or the third cut-off voltage has a value range of 38%-52% SOC corresponding to the voltage value range.

8. A battery cell, characterized in that: The battery cell is manufactured based on the method according to any one of claims 1 to 7.

9. An electronic device, characterized in that: The electronic device comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the electronic device implements the method as claimed in any one of claims 1 to 7.

10. A computer program product, characterized in that The invention comprises a computer program which, when executed, causes the method according to any one of claims 1 to 7 to be performed.

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