Battery cell formation method and device, 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 and device, electronic equipment and a computer program product.The method comprises the steps that a liquid-injected battery cell is charged with first set current till the charging voltage reaches first cut-off voltage; the first set current is greater than or equal to a preset current; at a first set temperature, standing the liquid-injected battery cell for a first set time length; the first set temperature is greater than or equal to a preset temperature; carrying out complete discharge treatment on the battery cell subjected to liquid injection; adopting a second set current to charge the battery cell filled with the liquid until the charging voltage reaches the first cut-off voltage to obtain a target battery cell meeting the set requirement; the second set current is smaller than the preset current; the set requirements include that the skeleton structure of the SEI film of the target battery cell meets the set structural characteristics, and / or the compactness of the SEI film meets a threshold value. According to the scheme, the high-temperature performance of the battery cell can be improved.

Description

Technical Field

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

[0002] Battery cell formation is a key process in battery cell manufacturing. Its main purpose is to activate the active substances inside the battery cell and form a solid electrolyte interface membrane (SEI membrane) on the surface of the active substances at the negative electrode of the battery cell.

[0003] At present, the industry generally adopts the method of small current charging to achieve battery cell formation, but the SEI film skeleton structure formed in this way is relatively small, resulting in poor performance of the battery cell at high temperature. Summary of the invention

[0004] The embodiments of the present application provide a battery cell formation method, device, electronic device and computer program product to solve the problem in the prior art that the SEI film formed by small current charging formation has a small skeleton structure, resulting in poor performance of the battery cell at high temperature.

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

[0006] The liquid-filled battery cell is charged with a first set current until the charging voltage reaches a first cut-off voltage; the first set current is greater than or equal to a preset current;

[0007] At a first set temperature, the liquid-filled battery cell is left to stand for a first set time; the first set temperature is greater than or equal to a preset temperature;

[0008] Performing a complete discharge process on the liquid-filled battery cell;

[0009] The liquid-filled battery cell is charged with a second set current until the charging voltage reaches the first cut-off voltage, thereby obtaining a target battery cell that meets the set requirements; the second set current is less than the preset current; the set requirements include that the skeleton structure of the SEI film of the target battery cell meets the set structural characteristics, and / or that the density of the SEI film meets a threshold value.

[0010] A second aspect of an embodiment of the present application provides a battery cell formation device, comprising:

[0011] A first charging module, used to charge the liquid-filled battery cell with a first set current until the charging voltage reaches a first cut-off voltage; the first set current is greater than or equal to a preset current;

[0012] A standing module, used for standing the liquid-filled battery cell for a first set time at a first set temperature; the first set temperature is greater than or equal to a preset temperature;

[0013] A discharge module, used for completely discharging the liquid-filled battery cell;

[0014] A second charging module is used to charge the liquid-filled battery cell with a second set current until the charging voltage reaches the first cut-off voltage, thereby obtaining a target battery cell that meets the set requirements; the second set current is less than the preset current; the set requirements include that the skeleton structure of the SEI film of the target battery cell meets the set structural characteristics, and / or that the density of the SEI film meets a threshold value.

[0015] 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.

[0016] A fourth aspect of the present application provides a computer program product. When the computer program product is run on an electronic device, the electronic device executes the steps of the method described in the first aspect.

[0017] 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.

[0018] As can be seen from the above, the present application first uses a first set current greater than or equal to a preset current to charge the liquid-filled battery cell to form a larger SEI skeleton structure. The liquid-filled battery cell is then left to stand at a higher ambient temperature to eliminate side reactions, stabilize the skeleton structure of the SEI film, and accelerate the diffusion of substances to promote the further formation of the SEI film. Finally, a second set current less than the preset current is used to charge the fully discharged liquid-filled battery cell again to form a denser SEI film on the basis of a stable SEI skeleton structure. After the above steps, the SEI film of the target battery cell obtained has a larger skeleton structure and relatively good density, thereby improving the high temperature performance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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.

[0020] Figure 1 This is a process of a battery cell formation method provided in an embodiment of the present application Figure 1 ;

[0021] Figure 2 This is a process of a battery cell formation method provided in an embodiment of the present application Figure 2 ;

[0022] Figure 3 This is a schematic diagram of voltage-time variation in a formation stage provided in an embodiment of the present application;

[0023] Figure 4 This is a comparison chart of high temperature performance of a target finished battery cell under different formation conditions provided in an embodiment of the present application;

[0024] Figure 5 It is a structural diagram of a battery cell formation device provided in an embodiment of the present application;

[0025] Figure 6 It is a structural diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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).

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] In order to illustrate the technical solution described in this application, a specific embodiment is provided below for illustration.

[0037] 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:

[0038] Step 101, charging the liquid-filled battery cell with a first set current until the charging voltage reaches a first cut-off voltage; the first set current is greater than or equal to a preset current.

[0039] Before the battery cell is formed, it is necessary to inject an appropriate amount of electrolyte into the semi-finished battery cell that has not been injected with electrolyte according to the battery cell production requirements to obtain the semi-finished battery cell after injection.

[0040] In some embodiments, the method of charging the liquid-filled battery cell with a first set current until the charging voltage reaches a first cut-off voltage further includes: allowing the liquid-filled semi-finished battery cell to stand for a second set time period to obtain the liquid-filled battery cell.

[0041] As the electrolyte is continuously injected, some tiny bubbles will be generated inside the semi-finished battery cell. The presence of bubbles will affect the uniform distribution of the electrolyte and thus affect the performance of the battery cell.

[0042] In order to reduce the impact of uneven distribution of electrolyte on the performance of the battery cell, the semi-finished battery cell after injection is left to stand. In this way, the bubbles inside the semi-finished battery cell have enough time to rise and be discharged in the electrolyte, thereby reducing the number of bubbles inside the semi-finished battery cell, ensuring that the electrolyte fully penetrates into the interior of the semi-finished battery cell, improving the uniformity of electrolyte distribution, improving the wetting effect of the electrode, and facilitating the formation of a more uniform and stable SEI film, while also helping to reduce the probability of local overheating and abnormal gas production caused by poor wetting.

[0043] The second set time is determined according to factors such as the chemical properties of the electrolyte, the internal structure of the battery cell and the amount of liquid injected, and the semi-finished battery cell after liquid injection is left to stand for the second set time to obtain the liquid-injected battery cell.

[0044] In some embodiments, the second set time period is 4-48 hours, for example, 24 hours.

[0045] After the standing still is completed, the charging and formation operation can be performed. Charging and formation can activate the active materials of the positive and negative electrodes in the battery cell, so that the battery cell reaches a state where it can efficiently carry out electrochemical reactions. During the charging and formation process, an SEI film will be generated on the negative electrode surface of the battery cell. The SEI film can effectively prevent the further occurrence of side reactions between the electrolyte and the negative electrode material to reduce the loss of active substances in the battery cell, such as reducing the loss of lithium content in the battery cell. The SEI film can also prevent solvent molecules from damaging the electrode materials, thereby improving the performance of the battery cell.

[0046] In some embodiments, the liquid-filled battery cell is charged with a first set current which is greater than or equal to a preset current.

[0047] In some embodiments, the preset current is a current value corresponding to 0.2 C, where C is the rated capacity of the battery cell.

[0048] In some embodiments, when the charging current is too large, the formed SEI film will be damaged. To ensure that the SEI film is not damaged, the first set current should not be too large. Accordingly, the value range of the first set current is the current value range corresponding to 0.2C-0.5C.

[0049] When the first set current is used to charge the first cut-off voltage, the charging operation of the first charging stage in the formation stage is completed.

[0050] The battery state of charge (SOC) is used to represent the cut-off voltage.

[0051] In some embodiments, the first cut-off voltage has a value range of 8%-12% SOC corresponding to the voltage value range. When the first cut-off voltage is reached, the film formation is completed, that is, the first cut-off voltage can also be called the film formation voltage.

[0052] By charging to the first cut-off voltage with a relatively large current, a SEI film with a large skeleton structure can be formed on the surface of the negative electrode of the liquid-filled battery cell.

[0053] In some embodiments, the method of charging the filled battery cell with a first set current until the charging voltage reaches a first cut-off voltage includes: charging the filled battery cell with the first set current at a second set temperature until the charging voltage reaches the first cut-off voltage; the second set temperature has a value range of 40°C-85°C.

[0054] On the basis of high current charging, the temperature of the charging environment is further limited, that is, charging with the first set current under the second set temperature environment of 40°C-85°C can further increase the skeleton structure of the SEI film.

[0055] Step 102, leaving the liquid-filled battery cell to stand for a first set time at a first set temperature; the first set temperature is greater than or equal to a preset temperature.

[0056] Wherein, the preset temperature is 40°C.

[0057] When the liquid-filled battery cell is charged with the first set current, along with the formation of the SEI film with a large skeleton structure, other side reactions also occur inside the liquid-filled battery cell.

[0058] The high temperature standing process in step 102 is a high temperature aging process. Through high temperature aging, unstable side reactions inside the liquid-filled battery cell are disintegrated, including the disintegration of the unstable SEI film, thereby making the skeleton structure of the SEI film more stable.

[0059] In addition, standing still can further promote the uniform distribution and full infiltration of the electrolyte inside the battery cell.

[0060] In some embodiments, the first set temperature is specifically set to 40°C-50°C, which is a temperature range that can already meet the high temperature aging requirements. Compared with higher temperatures, the heating energy consumption required in the temperature range of 40°C-50°C is relatively low, which can save energy resources, reduce energy waste, and reduce production costs.

[0061] Step 103: Completely discharge the liquid-filled battery cell.

[0062] After the liquid-filled battery cell is left at high temperature for high temperature aging, the remaining power in the liquid-filled battery cell is discharged. After the liquid-filled battery cell is fully discharged, its internal structure is more stable and the distribution of active materials is more uniform, which provides favorable conditions for the subsequent charging and formation process.

[0063] In some embodiments, a first set current is used to perform the discharge process.

[0064] The full discharge treatment can be carried out at room temperature without the need for additional heating or cooling equipment, which reduces the additional energy consumption caused by high or low temperature environments, saves temperature energy, and reduces production costs.

[0065] Step 104, using a second set current to charge the liquid-filled battery cell until the charging voltage reaches the first cut-off voltage, to obtain a target battery cell that meets the set requirements; the second set current is less than the preset current; the set requirements include that the skeleton structure of the SEI film of the target battery cell meets the set structural characteristics, and / or that the density of the SEI film meets the threshold.

[0066] After the high current charging or high temperature high current charging in the first charging stage, the SEI film on the negative electrode surface of the liquid-filled battery cell has a large skeleton structure, but the density of the SEI film is poor. The density of the SEI film is also crucial to the high temperature performance of the battery cell. Therefore, after full discharge, the liquid-filled battery cell is recharged with a smaller second set current.

[0067] The charging voltage in the second charging stage is also the first cut-off voltage.

[0068] In some embodiments, the value range of the second set current is a current value range corresponding to 0.05C-0.12C.

[0069] When charging with a small current, a single electron reaction is likely to occur inside the battery cell, which can reduce the amount of impurities generated during the formation of the SEI film, and is conducive to the formation of a purer and denser SEI film. Moreover, charging with a small current can reduce the polarization phenomenon inside the liquid-filled battery cell, so that the ions in the electrolyte are more evenly distributed on the electrode surface, which is conducive to the formation of a more uniform and dense SEI film. In addition, charging with a small current can also reduce the heat generated inside the liquid-filled battery cell during the charging process, reduce the thermal stress of the SEI film during the formation process, and improve the stability of the SEI film.

[0070] Through secondary charging with a small current, the SEI film is filled on the basis of the large skeleton structure, and a dense SEI film is formed on the negative electrode surface of the liquid-filled battery cell.

[0071] In some embodiments, the method of charging the filled battery cell with the second set current until the charging voltage reaches the first cut-off voltage to obtain the target battery cell that meets the set requirements includes: charging the filled battery cell with the second set current at a third set temperature until the charging voltage reaches the first cut-off voltage to obtain the target battery cell that meets the set requirements; the third set temperature is less than or equal to 10°C.

[0072] In order to further improve the density of the SEI film, the charging environment temperature is limited during the secondary charging, and the secondary charging is carried out in a low temperature environment.

[0073] When the temperature is lower than 0°C, lithium deposition will occur in the battery cell. Therefore, the first set temperature is usually set within the temperature range of 0-10°C.

[0074] In a low-temperature environment, the activity of the electrolyte in the injected battery cell is reduced, that is, the activity of the ions in the electrolyte is reduced, the migration speed is slow, and the probability of side reactions is reduced, which can reduce the occurrence of side reactions that hinder the formation of the SEI film and destroy the structure of the SEI film, and help form a denser SEI film. In addition, low-temperature formation can reduce gas production, improve the consistency of the battery cell interface, and thus improve the performance of the battery cell.

[0075] Charging at a low temperature combined with a small current can solve the problem of long-term charging with a small current, which increases the probability of side reactions, affects the formation of the SEI film, and destroys the SEI film, while retaining the advantage of dense film formation with a small current.

[0076] Compared with low-current charging, the density of the SEI film is further improved under low-temperature and low-current charging.

[0077] The high current charging in the first charging stage and the low current charging in the second charging stage promote the formation of the macro-skeleton structure of the SEI film and the improvement of the density of the SEI film.

[0078] The high temperature limit of the first charging stage and / or the low temperature limit of the second charging stage can further improve the skeleton structure stability and the density of the SEI film.

[0079] After the above two charging stages, a target cell that meets the set requirements is obtained. The skeleton structure of the SEI film of the target cell meets the set structural characteristics, and / or the density of the SEI film meets the set threshold. The set structural characteristics and thresholds are not limited in this application, as long as they can meet the production requirements.

[0080] The target battery cell has a larger SEI membrane skeleton structure and a dense SEI membrane. During use, there are fewer side reactions inside the battery cell, the battery cell has better stability, and it can maintain excellent performance in high temperature environments.

[0081] In the embodiment of the present application, the liquid-filled battery cell is first charged with a first set current greater than or equal to a preset current to form a larger SEI skeleton structure. The liquid-filled battery cell is then left to stand at a higher ambient temperature to eliminate side reactions, stabilize the skeleton structure of the SEI film, and accelerate the diffusion of substances to promote the further formation of the SEI film. Finally, a second set current less than the preset current is used to charge the fully discharged liquid-filled battery cell again to form a denser SEI film on the basis of a stable SEI skeleton structure. After the above steps, the SEI film of the target battery cell obtained has a larger skeleton structure and relatively good density, thereby improving the high temperature performance of the battery cell.

[0082] 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:

[0083] Step 201, charging the liquid-filled battery cell with a first set current until the charging voltage reaches a first cut-off voltage; the first set current is greater than or equal to a preset current.

[0084] 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.

[0085] Step 202, leaving the liquid-filled battery cell to stand for a first set time at a first set temperature; the first set temperature is greater than or equal to a preset temperature.

[0086] 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.

[0087] Step 203: Completely discharge the liquid-filled battery cell.

[0088] 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.

[0089] Step 204, using a second set current to charge the liquid-filled battery cell until the charging voltage reaches the first cut-off voltage, to obtain a target battery cell that meets the set requirements; the second set current is less than the preset current; the set requirements include that the skeleton structure of the SEI film of the target battery cell meets the set structural characteristics, and / or that the density of the SEI film meets the threshold.

[0090] The implementation process of this step is the same as the implementation process of step 104 in the aforementioned embodiment, and will not be repeated here.

[0091] Step 205 , charging the target battery cell with a third set current until the charging voltage reaches a second cut-off voltage.

[0092] In order to fully activate the active substances in the battery cell, the third charging stage is entered after two charges form a SEI film with a larger skeleton structure and better density.

[0093] The target battery cell is charged with the third set current to deeply activate the active material inside the target battery cell, ensuring that the active material in the target battery cell can fully participate in the subsequent charging and discharging process, thereby improving the storage performance of the finished battery cell.

[0094] The third charging stage does not impose too many restrictions on the formation temperature and formation current.

[0095] In some embodiments, the formation temperature of the third charging stage may be room temperature, which can reduce energy supply.

[0096] In some embodiments, the formation temperature of the third charging stage may also be another temperature higher than room temperature, such as 45° C., which can accelerate the formation speed of the third charging stage.

[0097] In some embodiments, the value range of the third set current is a current value range corresponding to 0.05C-0.5C.

[0098] In some embodiments, when entering the third charging stage, the SEI film is fully formed and can be charged with a large current. For example, the third set current is a current value corresponding to 0.5C, which can speed up the formation speed of the third charging stage, save time, and improve production efficiency.

[0099] When the charging voltage reaches the second cut-off voltage, the third charging is completed, which means that the charging formation is finished. The value range of the second cut-off voltage is the voltage value range corresponding to 48%-62% SOC.

[0100] During the entire formation stage, the formation is achieved under normal pressure (such as 1MPa). The voltage of the battery cell changes continuously over time. Figure 3 As shown, Figure 3 It is a schematic diagram of voltage-time variation in a formation stage provided in an embodiment of the present application.

[0101] Figure 3 In the figure, I1, I2 and I3 are the first set current, the second set current and the third set current respectively, and I1>I2. V1 and V2 are the first cut-off voltage and the second cut-off voltage respectively, and V0 is the voltage after the liquid-filled battery cell is fully discharged. V0 is the voltage value corresponding to 0% SOC, that is, the power at V0 is 0, and V0 <V1<V2。

[0102] The origin to V1 is the first charging stage, V1 to V0 is the high temperature aging and discharge stage, V0 to V1 is the second charging stage, and the subsequent V1 to V2 is the third charging stage. Figure 3 The changes in voltage at different stages during the cell formation process are introduced intuitively and clearly.

[0103] 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.

[0104] The present application divides the formation stage into multiple small stages, controls the current and / or temperature of each stage, sets a suitable cut-off voltage in each stage, and improves the formation efficiency.

[0105] Step 206: encapsulate the target battery cell to obtain a target finished battery cell.

[0106] Finally, the target battery cell that has undergone three charges and aging discharges is packaged to obtain the target finished battery cell.

[0107] Afterwards, users can divide the target finished battery cells into different capacities according to their needs and select the required battery cells.

[0108] The SEI film of the target finished battery cell obtained by the battery cell formation method described in the present application has a larger skeleton structure and relatively high density, and the high temperature performance of the battery cell is greatly improved. The following is proved by specific examples and data.

[0109] 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.

[0110] In the first charging stage, the second set temperature and the first set current are charged to the first cut-off voltage, i.e., 3.65V, which is the voltage value corresponding to 10% SOC; in the aging discharge stage, after aging at the first set temperature of 45°C, a full discharge operation is performed, discharging to 3.00V, which is the voltage value corresponding to 0% SOC; in the second charging stage, the third set temperature and the current value corresponding to the second set current of 0.1C are charged to the first cut-off voltage, i.e., 3.65V; in the third charging stage, the current value corresponding to the third set current of 0.5C is charged to the second cut-off voltage, i.e., 3.95V, which is the voltage value corresponding to 50% SOC; the pressure of the three charging stages is 1MPa. As shown in Table 1, Table 1 is a schematic table of formation conditions of each stage during formation provided in an embodiment of the present application.

[0111] Table 1 Schematic diagram of the chemical conditions at each stage of chemical formation

[0112]

[0113] Table 1 clearly shows the formation conditions of each sub-stage in the formation 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, embodiment 1, embodiment 2, embodiment 3 and embodiment 4 are formed.

[0114] Based on the above-mentioned formation conditions, the target finished battery cells corresponding to different formation scenarios are obtained by packaging.

[0115] High temperature will destroy the SEI film. High temperature treatment can be used to test the stability of the SEI film, that is, the stability of the skeleton structure. The fully charged target finished battery cells corresponding to different formation scenarios were stored in an 85°C environment for 24 hours. After that, they were measured at room temperature and pressure to measure the capacity retention rate, capacity recovery rate and thickness change rate of each target finished battery cell.

[0116] The capacity retention rate is the ratio of the remaining capacity of the target finished battery cell to the maximum full charge capacity.

[0117] The capacity recovery rate is the ratio of the dischargeable capacity of the target finished battery cell to the maximum full charge capacity after it is fully discharged and fully charged again.

[0118] After use, the battery cell will generally swell, so the thickness change rate is usually the thickness growth rate. Accordingly, the thickness change rate is the ratio of the increased thickness of the target finished battery cell to the original thickness.

[0119] like Figure 4 As shown, Figure 4 This is a comparison chart of the high temperature performance of a target finished battery cell under different formation conditions provided in an embodiment of the present application. Figure 4 The bar chart and line graph show the capacity retention rate, capacity recovery rate and thickness change rate of various target finished battery cells after high-temperature treatment. Figure 4 Corresponding to the following Table 2. As shown in Table 2, Table 2 is a high temperature performance table of a target finished battery cell under different formation conditions provided in an embodiment of the present application.

[0120] Table 2 High temperature performance of target finished battery cells under different formation conditions

[0121] plan Capacity retention rate Capacity recovery rate Thickness change rate Comparative Example 1 70.6％ 81.2％ 42.1％ Embodiment 1 73.5％ 90.8％ 42.3％ Embodiment 2 76.0％ 89.4％ 33.8％ Embodiment 3 75.9％ 90.4％ 36.3％ Embodiment 4 79.3％ 91.2％ 27.5％

[0122] It can be clearly seen from the chart that the capacity retention rate, capacity recovery rate and thickness change rate of the embodiment are all optimized compared with the comparative example.

[0123] The difference between Example 1 and Example 3 and between Example 2 and Example 4 is that the current in the first charging stage is different. The first set current of Example 3 is higher than the first set current of Example 1, and the first set current of Example 4 is higher than the first set current of Example 2. According to the values ​​of capacity retention rate, capacity recovery rate and thickness change rate, it can be concluded that in the first charging stage, the skeleton structure and density of the SEI film of the target finished battery cell obtained by charging with a larger current are better.

[0124] The difference between Example 1 and Example 2 and between Example 3 and Example 4 is that the temperature of the second charging stage is different. The third set temperature of Example 2 is lower than the third set temperature of Example 1, and the third set temperature of Example 4 is lower than the third set temperature of Example 3. Accordingly, according to the values ​​of capacity retention rate, capacity recovery rate and thickness change rate, in the second charging stage, the skeleton structure and density of the SEI film of the target finished battery cell obtained by low temperature charging are better.

[0125] Embodiment 4 adopts high temperature and high current charging in the first charging stage, adds high temperature aging treatment and complete discharge treatment, and adopts low temperature and low current charging in the second charging stage. It can be seen from the chart that the high temperature performance of embodiment 4 is the best among all the given solutions.

[0126] Therefore, the charging formation method combining high current and low current can improve the skeleton structure stability and SEI membrane compactness of the SEI membrane. Limiting the temperature of any one or both of the first charging stage and the second charging stage, such as the charging formation method combining high temperature and high current with low temperature and low current, can further improve the skeleton structure stability and SEI membrane compactness of the SEI membrane. Finally, a finished battery cell with excellent performance at high temperature is obtained.

[0127] In an embodiment of the present application, after obtaining a target battery cell having a larger SEI skeleton structure and relatively good SEI film density, charging is continued to fully activate the active substances in the target battery cell, and packaging is performed after the charging voltage reaches the second cut-off voltage to obtain a target finished battery cell that can be used.

[0128] See also Figure 5 , Figure 5 This is a structural diagram of a battery cell formation device provided in an embodiment of the present application. For the sake of ease of explanation, only the parts related to the embodiment of the present application are shown.

[0129] The battery cell formation device 500 includes: a first charging module 501 , a standing module 502 , a discharging module 503 , and a second charging module 504 .

[0130] The first charging module 501 is used to charge the liquid-filled battery cell with a first set current until the charging voltage reaches a first cut-off voltage; the first set current is greater than or equal to a preset current.

[0131] The standing module 502 is used to stand the liquid-filled battery cell for a first set time at a first set temperature; the first set temperature is greater than or equal to a preset temperature.

[0132] The discharge module 503 is used to completely discharge the liquid-filled battery cell.

[0133] The second charging module 504 is used to charge the liquid-filled battery cell with a second set current until the charging voltage reaches the first cut-off voltage, thereby obtaining a target battery cell that meets the set requirements; the second set current is less than the preset current; the set requirements include that the skeleton structure of the SEI film of the target battery cell meets the set structural characteristics, and / or that the density of the SEI film meets a threshold value.

[0134] In some embodiments, the static module is further used to:

[0135] The semi-finished battery cell after liquid injection is left to stand for a second set time to obtain the liquid-injected battery cell.

[0136] In some embodiments, the first charging module is further configured to:

[0137] At a second set temperature, the liquid-filled battery cell is charged with the first set current until the charging voltage reaches the first cut-off voltage; the value range of the second set temperature is 40° C.-85° C.

[0138] In some embodiments, the second charging module is further used for:

[0139] At a third set temperature, the liquid-filled battery cell is charged with the second set current until the charging voltage reaches the first cut-off voltage, thereby obtaining the target battery cell that meets the set requirements; and the third set temperature is less than or equal to 10°C.

[0140] In some embodiments, the device further comprises a charging packaging module, specifically configured to:

[0141] Charging the target battery cell with a third set current until the charging voltage reaches a second cut-off voltage;

[0142] The target battery cell is packaged to obtain a target finished battery cell.

[0143] In some embodiments, the first cut-off voltage has a value range of a voltage value corresponding to 8%-12% SOC, and / or the second cut-off voltage has a value range of a voltage value corresponding to 48%-62% SOC.

[0144] In some embodiments, the preset current is a current value corresponding to 0.2C, and / or the preset temperature is 40°C.

[0145] The battery cell formation device provided in the embodiment of the present application can implement each process of the embodiment of the above-mentioned battery cell formation method and can achieve the same technical effect. To avoid repetition, it will not be described here.

[0146] Figure 6 6 is a structural diagram of an electronic device provided in an embodiment of the present application. As shown in the figure, the electronic device 6 of this embodiment includes: at least one processor 60 ( Figure 6 Only one is shown in the figure), a memory 61, and a computer program 62 stored in the memory 61 and executable on the at least one processor 60, wherein the processor 60 implements the steps of any of the above-mentioned method embodiments when executing the computer program 62.

[0147] The electronic device 6 may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The electronic device 6 may include, but is not limited to, a processor 60 and a memory 61. Those skilled in the art will appreciate that Figure 6 It is only an example of the electronic device 6 and does not constitute a limitation of the electronic device 6. 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.

[0148] The processor 60 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.

[0149] The memory 61 may be an internal storage unit of the electronic device 6, such as a hard disk or memory of the electronic device 6. The memory 61 may also be an external storage device of the electronic device 6, 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 6. Further, the memory 61 may also include both an internal storage unit and an external storage device of the electronic device 6. The memory 61 is used to store the computer program and other programs and data required by the electronic device. The memory 61 may also be used to temporarily store data that has been output or is to be output.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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: The liquid-filled battery cell is charged with a first set current until the charging voltage reaches a first cut-off voltage; The first set current is greater than or equal to a preset current; At a first set temperature, leaving the liquid-filled battery cell to stand for a first set time; The first set temperature is greater than or equal to a preset temperature; Performing a complete discharge process on the liquid-filled battery cell; The liquid-filled battery cell is charged with a second set current until the charging voltage reaches the first cut-off voltage, thereby obtaining a target battery cell that meets the set requirements; the second set current is less than the preset current; the set requirements include that the skeleton structure of the SEI film of the target battery cell meets the set structural characteristics, and / or that the density of the SEI film meets a threshold value.

2. The method according to claim 1, characterized in that The method of charging the liquid-filled battery cell 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 second set time to obtain the liquid-injected battery cell.

3. The method according to claim 1, characterized in that The step of charging the liquid-filled battery cell with the first set current until the charging voltage reaches the first cut-off voltage includes: At a second set temperature, the liquid-filled battery cell is charged with the first set current until the charging voltage reaches the first cut-off voltage; the value range of the second set temperature is 40° C.-85° C.

4. The method according to claim 1, characterized in that: The step of charging the liquid-filled battery cell with the second set current until the charging voltage reaches the first cut-off voltage to obtain a target battery cell that meets the set requirements includes: At a third set temperature, the liquid-filled battery cell is charged with the second set current until the charging voltage reaches the first cut-off voltage, thereby obtaining the target battery cell that meets the set requirements; and the third set temperature is less than or equal to 10°C.

5. The method according to claim 1, characterized in that: The method further comprises: charging the liquid-filled battery cell with the second set current until the charging voltage reaches the first cut-off voltage and obtaining a target battery cell that meets the set requirements; Charging the target battery cell with a third set current until the charging voltage reaches a second cut-off voltage; The target battery cell is packaged to obtain a target finished battery cell.

6. The method according to claim 5, characterized in that The value range of the first cut-off voltage is a voltage value range corresponding to 8%-12% SOC, and / or the value range of the second cut-off voltage is a voltage value range corresponding to 48%-62% SOC.

7. The method according to claim 1, characterized in that The preset current is a current value corresponding to 0.2C, and / or the preset temperature is 40°C.

8. A battery cell formation device, characterized in that: include: A first charging module, used to charge the liquid-filled battery cell with a first set current until the charging voltage reaches a first cut-off voltage; The first set current is greater than or equal to a preset current; A standing module, used for standing the liquid-filled battery cell for a first set time at a first set temperature; The first set temperature is greater than or equal to a preset temperature; A discharge module, used for completely discharging the liquid-filled battery cell; A second charging module is used to charge the liquid-filled battery cell with a second set current until the charging voltage reaches the first cut-off voltage, thereby obtaining a target battery cell that meets the set requirements; the second set current is less than the preset current; the set requirements include that the skeleton structure of the SEI film of the target battery cell meets the set structural characteristics, and / or that the density of the SEI film meets a threshold value.

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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