Battery cell manufacturing method, battery cell, battery device, and energy storage device

Abstract

The application relates to a battery cell preparation method, a battery cell, a battery device and an energy storage device. The battery cell preparation method comprises detecting a diaphragm; a part of the diaphragm not overlapping with a negative pole piece is a reserved area; in a first direction, at least part of the reserved area is provided with a plurality of interval arranged diaphragm marks, and a first diaphragm mark interval is formed between adjacent diaphragm marks in a second direction; an initial value of the first diaphragm mark interval is L1, and a measured value of the first diaphragm mark interval is L2; the battery cell preparation method comprises: judging whether (L2-L1) / L1 is less than or equal to a first preset value; if part of the diaphragm section does not satisfy (L2-L1) / L1 less than or equal to the first preset value, the part of the diaphragm section is cut or discarded; if yes, the diaphragm 1 is qualified. The battery cell preparation method can reduce the risk of internal micro-short circuit and thermal runaway of the battery cell, improve the safety and reliability of the battery cell, and improve the quality of the battery cell.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method for preparing a battery cell, a battery cell, a battery device, and an energy storage device. Background Technology

[0002] An energy storage battery is an electrochemical device that enables the charging, discharging, and storage of electrical energy. It is mainly used for energy storage, emergency power supply, and grid peak shaving. It is the core component of an energy storage system and has the characteristics of high safety, long cycle life, and high efficiency.

[0003] In related technologies, the separator of energy storage battery cells is prone to wrinkles, uneven tension and abnormal stress release during manufacturing, which can lead to separator runaway and local deformation, increasing the risk of micro-short circuits and thermal runaway inside the cell, easily causing cell safety failure, and seriously affecting the product quality and reliability of the cell. Summary of the Invention

[0004] Therefore, it is necessary to provide a method for preparing a battery cell, a battery cell, a battery device, and an energy storage device to address the problems that easily occur in the separator of energy storage batteries, such as wrinkles, uneven tension, and abnormal stress release, which can lead to cell safety failure and affect the quality and reliability of battery cell products.

[0005] A method for preparing a battery cell includes testing a separator;

[0006] The separator partially overlaps with the negative electrode sheet. In a first direction, the size of the separator is larger than the size of the negative electrode sheet. The portion of the separator that does not overlap with the negative electrode sheet is a reserved area. In the first direction, the reserved area is located on at least one side of the negative electrode sheet. At least a portion of the reserved area is provided with a plurality of spaced-apart separator marks. In a second direction, a first separator mark interval is formed between adjacent separator marks. The initial value of the first separator mark interval is L1, and the measured value of the first separator mark interval is L2. The battery cell preparation method includes:

[0007] Determine whether (L2-L1) / L1 is less than or equal to the first preset value;

[0008] If a portion of the diaphragm does not satisfy (L2-L1) / L1 being less than or equal to the first preset value, then the portion of the diaphragm is cut or discarded.

[0009] If so, the diaphragm is qualified.

[0010] In one embodiment of this application, the method further includes inspecting a first separator roll, wherein a qualified first separator roll forms the separator, and the battery cell preparation method includes:

[0011] Obtain the second diaphragm roll;

[0012] The diaphragm mark is set on the second diaphragm roll, and a second diaphragm mark interval is formed between adjacent diaphragm marks in the second direction. The initial value of the second diaphragm mark interval is L3, which is equal to the initial value of the first diaphragm mark interval L1.

[0013] The second diaphragm roll is pre-cut to obtain the third diaphragm roll;

[0014] The third diaphragm roll is left to stand for a time T.

[0015] The third diaphragm roll is cut to obtain the first diaphragm roll;

[0016] Each of the second diaphragm marking intervals is detected to obtain the measured value L4 of the second diaphragm marking interval;

[0017] Determine whether (L4-L3) / L3 is less than or equal to the first preset value;

[0018] If a portion of the first diaphragm roll does not satisfy (L4-L3) / L3 being less than or equal to the first preset value, then the portion of the first diaphragm roll is cut.

[0019] If so, the diaphragm is obtained.

[0020] In one embodiment of this application, in the step of obtaining the second diaphragm roll, the tension borne by the second diaphragm roll is 100N-200N;

[0021] And / or, in the step of pre-slitting the second diaphragm roll to obtain the third diaphragm roll, the tension borne by the second diaphragm roll and the third diaphragm roll is 50N-100N;

[0022] And / or, in the step of cutting the third diaphragm roll to obtain the first diaphragm roll, the tension borne by the first diaphragm roll and the third diaphragm roll is 300N-400N.

[0023] In one embodiment of this application, before the step of determining whether (L2-L1) / L1 is less than or equal to a first preset value, the method further includes:

[0024] The diaphragm, the positive electrode, and the negative electrode are wound together;

[0025] During the winding process, each of the first diaphragm mark intervals is detected to obtain the measured value L2 of the first diaphragm mark interval;

[0026] And / or, after the step of determining whether (L2-L1) / L1 is less than or equal to a first preset value, the method further includes: if so, obtaining the battery cell.

[0027] In one embodiment of this application, during the step of winding the diaphragm, the positive electrode, and the negative electrode, the tension borne by the diaphragm is 400N-500N.

[0028] In one embodiment of this application, the diaphragm marking is a colored marking or the diaphragm marking is colored under a preset light.

[0029] In one embodiment of this application, the first preset value ranges from 0.3% to 5%.

[0030] In one embodiment of this application, the reserved area includes a first reserved area and / or a second reserved area. The first reserved area is located on the side where the negative electrode tab is disposed on the negative electrode sheet, and the second reserved area is located on the side away from the negative electrode sheet where the negative electrode tab is disposed. The first reserved area and / or the second reserved area are provided with the diaphragm mark.

[0031] In one embodiment of this application, in the first direction, the size of the first reserved area is c1, and the value of c1 ranges from 3mm to 5mm, and / or the size of the second reserved area is c2, and the value of c2 ranges from 1.5mm to 2mm.

[0032] In one embodiment of this application, in the first direction, the distance between the diaphragm mark and the edge of the first reserved area is d, and the value of the distance d is in the range of 1mm-2mm.

[0033] In one embodiment of this application, the battery cell preparation method further includes detecting the positive electrode roll and / or the negative electrode roll;

[0034] The positive electrode roll includes a positive electrode foil, with positive electrode tabs spaced apart on one side of the positive electrode foil. A positive electrode foil mark is provided at each positive electrode tab, and a positive electrode foil mark interval is formed between adjacent positive electrode foil marks. The initial value of the positive electrode foil mark interval is a1, and the measured value of the positive electrode foil mark interval is a2. When the battery cell preparation method inspects the positive electrode roll, the battery cell preparation method includes:

[0035] The positive electrode foil mark is set at the positive electrode tab, and the value of the positive electrode foil mark interval is the initial value a1 of the positive electrode foil mark interval;

[0036] A positive electrode active material is coated onto the positive electrode foil to obtain a positive electrode semi-finished product.

[0037] The positive electrode semi-finished product is rolled to obtain the positive electrode coil;

[0038] Each of the positive electrode foil marking intervals is detected to obtain the measured value a2 of the positive electrode foil marking interval;

[0039] Determine whether (a2-a1) / a1 is less than or equal to the second preset value;

[0040] If a portion of the positive electrode coil does not satisfy (a2-a1) / a1 being less than or equal to the second preset value, then the portion of the positive electrode coil is cut.

[0041] If so, the positive electrode roll is pre-cut and cut to obtain the positive electrode sheet;

[0042] And / or,

[0043] The negative electrode roll includes a negative electrode foil, with negative electrode tabs spaced apart on one side of the negative electrode foil. Negative electrode foil markings are provided at the negative electrode tabs, and negative electrode foil marking intervals are formed between adjacent negative electrode foil markings. The initial value of the negative electrode foil marking interval is b1, and the measured value of the negative electrode foil marking interval is b2. When the battery cell preparation method inspects the negative electrode roll, the battery cell preparation method includes:

[0044] The negative electrode foil mark is set at the negative electrode tab, and the value of the negative electrode foil mark interval is the initial value b1 of the negative electrode foil mark interval;

[0045] A negative electrode active material is coated onto the negative electrode foil to obtain a negative electrode sheet semi-finished product.

[0046] The negative electrode semi-finished product is rolled to obtain the negative electrode coil;

[0047] Each of the negative electrode foil marking intervals is detected to obtain the measured value b2 of the negative electrode foil marking interval;

[0048] Determine whether (b2-b1) / b1 is less than or equal to the third preset value;

[0049] If a portion of the negative electrode coil does not satisfy (b2-b1) / b1 being less than or equal to the third preset value, then the portion of the negative electrode coil is cut.

[0050] If so, the negative electrode roll is pre-cut and cut to obtain the negative electrode sheet.

[0051] In one embodiment of this application, the second preset value ranges from 0.5% to 0.8%, and the third preset value ranges from 0.1% to 0.2%.

[0052] A battery cell, the battery cell comprising:

[0053] Positive electrode sheet;

[0054] Negative electrode sheet;

[0055] A separator is disposed between the positive electrode and the negative electrode, and the separator partially overlaps with the negative electrode. In a first direction, the size of the separator is larger than the size of the negative electrode. The portion of the separator that does not overlap with the negative electrode is a reserved area. In the first direction, the reserved area is located on at least one side of the negative electrode. At least a portion of the reserved area is provided with a plurality of spaced separator marks.

[0056] A battery device includes the aforementioned battery cell, and the battery device includes one or more of the following: battery module, battery pack, and energy storage battery.

[0057] An electrical device includes the battery device described above, the battery device being used to provide electrical energy to the electrical device.

[0058] An energy storage device includes the battery device described above, the battery device being used to store electrical energy for the energy storage device.

[0059] The aforementioned battery cell preparation method is used to inspect the separator. This method filters out separators that do not meet the requirements by determining whether (L2-L1) / L1 is less than or equal to a first preset value. These separators exhibit wrinkles, uneven tension, or abnormal stress release. These unqualified separators are cut or discarded, thus obtaining separators whose first separator marking interval measurement value L2 meets the requirements, i.e., qualified separators. Qualified separators are less likely to cause problems such as separator runaway or localized deformation. Using these qualified separators to prepare battery cells can reduce the risk of internal micro-short circuits and thermal runaway, improve the safety and reliability of the battery cells, and thus significantly improve the product quality of the battery cells.

[0060] The aforementioned battery cell, prepared using the aforementioned battery cell preparation method, has the same beneficial effects as the aforementioned battery cell preparation method, which will not be elaborated here.

[0061] The aforementioned battery device, including the aforementioned battery cell, has the same beneficial effects as the battery cell, which will not be elaborated here.

[0062] The aforementioned electrical device, including the aforementioned battery device, has the same beneficial effects as the battery device, which will not be elaborated here.

[0063] The aforementioned energy storage device, including the aforementioned battery device, has the same beneficial effects as the battery device, which will not be elaborated here. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of the cell structure in the battery cell of this application.

[0065] Figure 2 This is a schematic diagram of the positive electrode foil / negative electrode foil in the battery cell of this application.

[0066] Figure 3 This is a flowchart of the battery cell preparation method (specifically for the separator) of this application.

[0067] Explanation of reference numerals in the attached figures:

[0068] 1. Diaphragm; 101. Reserved area; 1011. First reserved area; 1012. Second reserved area;

[0069] 2. Negative electrode sheet; 201. Negative electrode foil; 2011. Negative electrode tab;

[0070] 3. Diaphragm marking;

[0071] 401, Positive electrode foil; 4011, Positive electrode tab;

[0072] 5. Marking of positive electrode foil;

[0073] 6. Marking of negative electrode foil. Detailed Implementation

[0074] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0075] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0076] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0077] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0078] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0079] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0080] See Figures 1-3 As shown, an embodiment of this application provides a method for preparing a battery cell, including testing a separator 1; the separator 1 is partially overlapped with the negative electrode 2, the size of the separator 1 is larger than the size of the negative electrode 2 in a first direction, the portion of the separator 1 that does not overlap with the negative electrode 2 is a reserved area 101, the reserved area 101 is located on at least one side of the negative electrode 2 in the first direction, at least a portion of the reserved area 101 is provided with a plurality of spaced separator marks 3, and a first separator mark interval is formed between adjacent separator marks 3 in a second direction; the initial value of the first separator mark interval is L1, and the measured value of the first separator mark interval is L2; ​​the battery cell preparation method includes: determining whether (L2-L1) / L1 is less than or equal to a first preset value; if a portion of the separator 1 does not satisfy (L2-L1) / L1 being less than or equal to the first preset value, then the portion of the separator 1 is cut or discarded; if so, the separator 1 is qualified.

[0081] This battery cell preparation method is used to inspect the separator 1. By determining whether (L2-L1) / L1 is less than or equal to a first preset value, this method can screen out separators 1 that do not meet the requirements. These separators 1 are those with wrinkles, uneven tension, or abnormal stress release. These unqualified separators 1 are cut or discarded, thus obtaining separators 1 that meet the requirements for the first separator marking interval measurement value L2, i.e., qualified separators 1. Qualified separators 1 are less likely to cause problems such as separator runaway or localized deformation. Using these qualified separators 1 to prepare battery cells can reduce the risk of internal micro-short circuits and thermal runaway, improve the safety and reliability of the battery cells, and thus significantly improve the product quality of the battery cells.

[0082] The battery cell preparation method of this application tests the separator 1. In the battery cell, the separator 1 is disposed between the positive electrode and the negative electrode 2 to physically isolate the positive and negative electrodes in order to avoid short circuits inside the battery cell.

[0083] See Figure 1As shown, the separator 1 is wound with the positive electrode and the negative electrode 2 to form a battery cell. In the battery cell, the separator 1 and the negative electrode 2 partially overlap. In a first direction, the size of the separator 1 is larger than the size of the negative electrode 2. The first direction refers to the width direction of the separator 1, the positive electrode, and the negative electrode 2. Figure 1 As indicated by the middle arrow y-y', the width of the diaphragm 1 is greater than the width of the negative electrode 2. The portion of the diaphragm 1 that does not overlap with the negative electrode 2 is a reserved area 101, which is located on at least one side of the negative electrode 2 in the first direction.

[0084] In one embodiment, depending on the configuration requirements of different battery cell products, the reserved area 101 in the first direction can be located on one side of the negative electrode plate 2 or on both sides of the negative electrode plate 2. When the reserved area 101 is located on both sides of the negative electrode plate 2, the width (dimension in the first direction) of the reserved area 101 on both sides of the negative electrode plate 2 can be the same or different. Of course, the width of the reserved area 101 should be sufficient to allow for the setting of the separator mark 3.

[0085] At least a portion of the reserved area 101 is provided with a number of spaced-apart diaphragm marks 3. The diaphragm marks 3 are spaced-apart in a second direction, which refers to the length direction of the diaphragm 1, the positive electrode plate, and the negative electrode plate 2. For example, the second direction... Figure 1 As shown by the middle arrow x-x', the number of diaphragm marks 3 can be selected according to the length of diaphragm 1 (the size of diaphragm 1 in the second direction). This application does not limit the number of diaphragm marks 3.

[0086] In one embodiment, depending on the requirements of different battery cell products, a number of spaced-apart diaphragm marks 3 can be set in a portion of the reserved area 101, or a number of spaced-apart diaphragm marks 3 can be set in the entire reserved area 101. In one embodiment, adjacent diaphragm marks 3 are evenly spaced to facilitate subsequent detection of the distance between adjacent diaphragm marks 3.

[0087] In the second direction, a first diaphragm mark interval is formed between adjacent diaphragm marks 3. The first diaphragm mark interval refers to the distance between adjacent diaphragm marks 3 in the second direction. The initial value of the first diaphragm mark interval is L1, and the measured value of the first diaphragm mark interval is L2.

[0088] The initial value L1 of the first diaphragm mark interval refers to the initial distance between adjacent diaphragm marks 3 when diaphragm marks 3 are set on diaphragm 1. The measured value L2 of the first diaphragm mark interval refers to the detection distance between adjacent diaphragm marks 3 during the subsequent preparation of diaphragm 1.

[0089] The battery cell preparation method of this application includes: determining whether (L2-L1) / L1 is less than or equal to a first preset value; if a portion of the separator 1 does not satisfy (L2-L1) / L1 being less than or equal to the first preset value, then the portion of the separator 1 is cut or discarded; if so, then the separator 1 is qualified.

[0090] By testing the diaphragm 1 using the above method, we can obtain diaphragms 1 whose measured value L2 of the first diaphragm marking interval meets the requirements, i.e., obtain qualified diaphragms 1. Using these qualified diaphragms 1 to prepare battery cell products can reduce the risk of micro-short circuits and thermal runaway inside the battery cell, improve the safety and reliability of the battery cell, and thus significantly improve the product quality of the battery cell.

[0091] In one embodiment of this application, the battery cell preparation method further includes inspecting a first separator roll, and the qualified first separator roll forms a separator 1. The battery cell preparation method includes: obtaining a second separator roll; setting separator marks 3 on the second separator roll, at which time a second separator mark interval is formed between adjacent separator marks 3 in the second direction, the initial value of the second separator mark interval is L3, and the initial value of the second separator mark interval L3 is equal to the initial value of the first separator mark interval L1; pre-splitting the second separator roll to obtain a third separator roll; letting the third separator roll stand for a time T; splitting the third separator roll to obtain the first separator roll; inspecting each second separator mark interval to obtain a measured value L4 of the second separator mark interval; determining whether (L4-L3) / L3 is less than or equal to a first preset value; if a portion of the first separator roll does not satisfy (L4-L3) / L3 being less than or equal to the first preset value, then cutting a portion of the first separator roll; if so, obtaining the separator 1.

[0092] It should be noted that during the preparation of separator 1, multiple intermediate products will be generated. For example, according to the order of the preparation process, these intermediate products include: the second separator roll (or large separator roll), the third separator roll (or medium separator roll, separator semi-finished product roll), the first separator roll (or small separator roll), and the finished separator roll (i.e., separator 1 in a rolled state). After separator 1 is wound with the positive electrode and negative electrode 2, it forms a battery cell.

[0093] In one embodiment, the battery cell preparation method further includes inspecting the first separator roll, and the qualified first separator roll is a finished separator roll. The first separator roll is a large separator roll, and the width of the first separator roll is typically 5m, that is, the dimension of the first separator roll in the first direction is typically 5m.

[0094] When inspecting the first diaphragm roll, the battery cell preparation method includes:

[0095] Step S101: Obtain the second diaphragm roll.

[0096] In one embodiment, the second diaphragm roll may be a diaphragm roll formed by mixing raw materials, extrusion shaping, stretching, extraction, shaping and coating; or, the second diaphragm roll may be a diaphragm roll formed by mixing raw materials, extrusion shaping, stretching, extraction and shaping.

[0097] Step S102: Set diaphragm mark 3 on the second diaphragm roll. At this time, a second diaphragm mark interval is formed between adjacent diaphragm marks 3 in the second direction. The initial value of the second diaphragm mark interval is L3.

[0098] Along the second direction, diaphragm marks 3 are provided on the second diaphragm roll, with adjacent diaphragm marks 3 evenly spaced apart. The process of providing diaphragm marks 3 on the second diaphragm roll can be performed simultaneously with the coating step or after the coating step. The shape of the diaphragm marks 3 can be circular, triangular, etc., and this application does not impose any limitations on this.

[0099] After the diaphragm mark 3 is set, a second diaphragm mark interval is formed between adjacent diaphragm marks 3 in the second direction, and the distance between adjacent diaphragm marks 3 is the initial value L3 of the second diaphragm mark interval.

[0100] Step S103: Pre-cut the second diaphragm roll to obtain the third diaphragm roll.

[0101] The second diaphragm roll with diaphragm mark 3 set is pre-cut to obtain the third diaphragm roll. The third diaphragm roll is the middle roll of the diaphragm. The width of the third diaphragm roll is usually 1m, that is, the size of the third diaphragm roll in the first direction is usually 1m.

[0102] Depending on the width of the second diaphragm roll, there are usually multiple third diaphragm rolls obtained by pre-splitting. For example, when the width of the second diaphragm roll is 5m, five third diaphragm rolls are obtained by pre-splitting, and the width of each third diaphragm roll is 1m.

[0103] Step S104: Let the third diaphragm roll stand for time T.

[0104] The third diaphragm roll is left to stand for a period of time T, for example, 24 hours. During this standing period, the third diaphragm roll will release the stress generated during the molding process.

[0105] Step S105: The third diaphragm roll is cut to obtain the first diaphragm roll.

[0106] After settling, the third diaphragm roll is slit to obtain the first diaphragm roll, which is a small diaphragm roll, typically 200mm wide. Similarly, depending on the width of the third diaphragm roll, multiple first diaphragm rolls are usually obtained by slitting.

[0107] Step S106: Detect each second diaphragm mark interval to obtain the measured value L4 of the second diaphragm mark interval.

[0108] During the process of obtaining the first diaphragm roll from the second diaphragm roll through a series of steps, due to factors such as the inability to determine the molecular weight of the diaphragm polymer material and the need for online preparation, the diaphragm is prone to problems such as incomplete stress release and wrinkles. Therefore, it is necessary to inspect the stress release of the diaphragm to determine if any abnormalities exist. Specifically, after slitting, for each second diaphragm marking interval of the first diaphragm roll, the measured value L4 of the second diaphragm marking interval is obtained.

[0109] Step S107: Determine whether (L4-L3) / L3 is less than or equal to the first preset value.

[0110] Based on the initial value L3 of the second diaphragm marking interval and the measured value L4 of the second diaphragm marking interval, calculate whether the result of (L4-L3) / L3 is less than or equal to a first preset value. The first preset value is a pre-set error value. In one embodiment, the first preset value ranges from 0.3% to 5%, for example, it can be 0.3%, 0.6%, 1.5%, 2.2%, 3.6%, 4.5%, 5%, etc.

[0111] Step S108: If a portion of the first diaphragm roll does not satisfy (L4-L3) / L3 being less than or equal to the first preset value, then the portion of the first diaphragm roll is cut.

[0112] If a section of the first diaphragm roll does not meet the requirement that (L4-L3) / L3 is less than or equal to the first preset value, i.e., greater than the first preset value, then the section of the first diaphragm roll that does not meet the requirement is cut.

[0113] In one embodiment, the stress release of the first diaphragm portion that has been cut off can be facilitated by secondary unwinding until the requirements are met.

[0114] Step S109: If yes, then obtain diaphragm 1.

[0115] If the first diaphragm roll satisfies (L4-L3) / L3 being less than or equal to the first preset value, then the first diaphragm roll becomes the finished diaphragm roll.

[0116] In one embodiment of this application, in the step of obtaining the second diaphragm roll, the tension borne by the second diaphragm roll is 100N-200N; and / or, in the step of pre-slitting the second diaphragm roll to obtain the third diaphragm roll, the tension borne by the second diaphragm roll and the third diaphragm roll is 50N-100N; and / or, in the step of slitting the third diaphragm roll to obtain the first diaphragm roll, the tension borne by the first diaphragm roll and the third diaphragm roll is 300N-400N.

[0117] In one embodiment, in step S101, a second diaphragm roll is obtained online. The second diaphragm roll is in an up-wound state. At this time, the tension borne by the second diaphragm roll is 100N-200N. For example, the tension borne by the second diaphragm roll can be 100N, 120N, 150N, 180N, 200N, etc.

[0118] In one embodiment, in step S103, a third diaphragm roll is obtained online, while the second and third diaphragm rolls are in an up-wound state. At this time, the tension borne by the second and third diaphragm rolls is 50N-100N. For example, the tension borne by the second and third diaphragm rolls can be 50N, 65N, 80N, 96N, 100N, etc.

[0119] In one embodiment, in step S105, a first diaphragm roll is obtained online. The first and third diaphragm rolls are in an up-wound state. At this time, the tension borne by the first and third diaphragm rolls is 300N-400N. For example, the tension borne by the first and third diaphragm rolls can be 300N, 320N, 350N, 390N, 400N, etc.

[0120] In one embodiment, the following conditions may also be met simultaneously: in the step of obtaining the second diaphragm roll, the tension borne by the second diaphragm roll is 100N-200N; and in the step of pre-cutting the second diaphragm roll to obtain the third diaphragm roll, the tension borne by the second and third diaphragm rolls is 50N-100N; and in the step of cutting the third diaphragm roll to obtain the first diaphragm roll, the tension borne by the first and third diaphragm rolls is 300N-400N.

[0121] In one embodiment of this application, before determining whether (L2-L1) / L1 is less than or equal to a first preset value, the method further includes: winding the separator 1, the positive electrode sheet, and the negative electrode sheet 2; during the winding process, detecting each first separator mark interval to obtain a measured value L2 of the first separator mark interval; and / or, after determining whether (L2-L1) / L1 is less than or equal to the first preset value, the method further includes: if so, obtaining the battery cell.

[0122] In one embodiment, when the battery cell preparation method of this application tests the separator 1, the battery cell preparation method includes:

[0123] Step S201: The diaphragm 1, the positive electrode plate, and the negative electrode plate 2 are wound.

[0124] After the separator is prepared, a finished separator roll, namely separator 1 in a rolled state, is obtained. Separator 1, positive electrode plate and negative electrode plate 2 are wound together to form a cell roll. Separator 1 is placed between positive electrode plate and negative electrode plate 2 to isolate positive electrode plate and negative electrode plate 2 and prevent short circuit inside the cell.

[0125] Step S202: During the winding process, each first diaphragm mark interval is detected to obtain the measured value L2 of the first diaphragm mark interval.

[0126] During the winding process of the diaphragm 1, the positive electrode plate, and the negative electrode plate 2, due to the need for winding on a wire, the diaphragm 1 is prone to problems such as poor stress release and wrinkles. It is necessary to inspect the stress release of the diaphragm to determine if any abnormalities exist. Specifically, during the winding process of the diaphragm 1, the interval between each first diaphragm mark is inspected to obtain the measured value L2 of the first diaphragm mark interval.

[0127] Step S203: Determine whether (L2-L1) / L1 is less than or equal to the first preset value.

[0128] Based on the initial value L1 of the first diaphragm marking interval and the measured value L2 of the first diaphragm marking interval, calculate whether the result of (L2-L1) / L1 is less than or equal to a first preset value. The first preset value is a pre-set error value. In one embodiment, the range of the first preset value is 0.3%-5%, for example, the first preset value can be 0.3%, 0.6%, 1.5%, 2.2%, 3.6%, 4.5%, 5%, etc.

[0129] Step S204: If a portion of the diaphragm 1 does not satisfy (L2-L1) / L1 being less than or equal to the first preset value, then the portion of the diaphragm 1 is cut or discarded.

[0130] If a section of diaphragm 1 does not satisfy (L2-L1) / L1 being less than or equal to the first preset value, i.e., greater than the first preset value, then the section of diaphragm 1 is cut or discarded.

[0131] In one embodiment, the stress release of the cut-off diaphragm 1 portion can be promoted by secondary unwinding until the requirements are met.

[0132] In one embodiment, the initial value L1 of the first diaphragm marking interval is the same as the initial value L3 of the second diaphragm marking interval.

[0133] Step S205: If yes, then diaphragm 1 is qualified.

[0134] If diaphragm 1 satisfies (L2-L1) / L1 being less than or equal to the first preset value, then diaphragm 1 is qualified and a battery cell is obtained.

[0135] In one embodiment of this application, during the step of winding the diaphragm 1, the positive electrode plate and the negative electrode plate 2, the tension borne by the diaphragm 1 is 400N-500N.

[0136] In one embodiment, in step S201, the diaphragm 1, the positive electrode plate and the negative electrode plate 2 are wound online. The diaphragm 1 is in an up-wound state. At this time, the tension borne by the diaphragm 1 is 400N-500N. For example, the tension borne by the diaphragm 1 can be 400N, 410N, 450N, 480N, 500N, etc.

[0137] See Figure 3 As shown, the following is an overall description of the battery cell preparation method with regard to separator 1:

[0138] Step S1: Obtain the second diaphragm roll.

[0139] The second diaphragm roll is a large diaphragm roll, which can be formed by raw material mixing, extrusion shaping, stretching, extraction, shaping and coating; or by raw material mixing, extrusion shaping, stretching, extraction and shaping.

[0140] Step S2: Set diaphragm mark 3 on the second diaphragm roll. At this time, a second diaphragm mark interval is formed between adjacent diaphragm marks 3 in the second direction. The initial value of the second diaphragm mark interval is L3.

[0141] Along the second direction, diaphragm marks 3 are set on the second diaphragm roll, with adjacent diaphragm marks 3 evenly spaced apart. The process of setting diaphragm marks 3 on the second diaphragm roll can be performed simultaneously with the coating step or after the coating step.

[0142] After the diaphragm mark 3 is set, a second diaphragm mark interval is formed between adjacent diaphragm marks 3 in the second direction. At this time, the distance between adjacent diaphragm marks 3 is the initial value L3 of the second diaphragm mark interval, which is also the initial value L1 of the first diaphragm mark interval, i.e., L1=L3.

[0143] Step S3: Pre-cut the second diaphragm roll to obtain the third diaphragm roll.

[0144] The second diaphragm roll with diaphragm mark 3 set is pre-cut to obtain the third diaphragm roll. The third diaphragm roll is the middle roll of the diaphragm. The width of the third diaphragm roll is usually 1m, that is, the size of the third diaphragm roll in the first direction is usually 1m.

[0145] Step S4: Let the third diaphragm roll stand for time T.

[0146] The third diaphragm roll is left to stand for a period of time T, for example, 24 hours. During this standing period, the third diaphragm roll will release the stress generated during the molding process.

[0147] Step S5: Cut the third diaphragm roll to obtain the first diaphragm roll.

[0148] After standing, the third diaphragm roll is cut to obtain the first diaphragm roll, which is a small diaphragm roll, and the width of the first diaphragm roll is usually 200mm.

[0149] Step S6: Detect each second diaphragm mark interval to obtain the measured value L4 of the second diaphragm mark interval.

[0150] After the slitting is completed, for each second diaphragm mark interval of the first diaphragm roll, the measured value L4 of the second diaphragm mark interval is obtained.

[0151] Step S7: Determine whether (L4-L3) / L3 is less than or equal to the first preset value.

[0152] Based on the initial value L3 of the second diaphragm marking interval and the measured value L4 of the second diaphragm marking interval, calculate whether the result of (L4-L3) / L3 is less than or equal to the first preset value.

[0153] Step S8: If a portion of the first diaphragm roll does not satisfy (L4-L3) / L3 being less than or equal to the first preset value, then the portion of the first diaphragm roll is cut.

[0154] If a section of the first diaphragm roll does not meet the requirement that (L4-L3) / L3 is less than or equal to the first preset value, then the section of the first diaphragm roll that does not meet the requirement is cut.

[0155] Step S9, if yes, then obtain diaphragm 1.

[0156] If the first diaphragm roll satisfies (L4-L3) / L3 being less than or equal to the first preset value, then the first diaphragm roll becomes the finished diaphragm roll, i.e., the diaphragm 1 in the rolled state.

[0157] Step S10: The diaphragm 1, the positive electrode plate, and the negative electrode plate 2 are wound.

[0158] The separator 1, the positive electrode plate, and the negative electrode plate 2 are wound to form a battery cell roll, with the separator 1 disposed between the positive electrode plate and the negative electrode plate 2.

[0159] Step S11: During the winding process, each first diaphragm mark interval is detected to obtain the measured value L2 of the first diaphragm mark interval.

[0160] Because it is necessary to wind the diaphragm 1, the positive electrode plate and the negative electrode plate 2, during the winding process, for the diaphragm 1, the first diaphragm mark interval is detected to obtain the measured value L2 of the first diaphragm mark interval.

[0161] Step S12: Determine whether (L2-L1) / L1 is less than or equal to the first preset value.

[0162] Based on the initial value L1 of the first diaphragm marking interval and the measured value L2 of the first diaphragm marking interval, calculate whether the result of (L2-L1) / L1 is less than or equal to a first preset value. The initial value L1 of the first diaphragm marking interval is the initial value L3 of the second diaphragm marking interval.

[0163] Step S13: If a portion of the diaphragm 1 does not satisfy (L2-L1) / L1 being less than or equal to the first preset value, then the portion of the diaphragm 1 is cut or discarded.

[0164] If a section of diaphragm 1 does not satisfy (L2-L1) / L1 being greater than the first preset value, then the section of diaphragm 1 is cut or discarded.

[0165] Step S14: If yes, then diaphragm 1 is qualified.

[0166] If diaphragm 1 satisfies (L2-L1) / L1 being less than or equal to the first preset value, then diaphragm 1 is qualified and a battery cell is obtained.

[0167] In one embodiment of this application, the diaphragm mark 3 is a colored mark or the diaphragm mark 3 is colored under a preset light.

[0168] In one embodiment, the diaphragm mark 3 can be applied by roller coating, and the diaphragm mark 3 can be a colored mark or a mark that develops color under a preset light. For example, the diaphragm mark 3 can be a colored UV (Ultraviolet curing adhesives or UV-curable adhesives, also known as photosensitive adhesives) dot, which can develop color under ultraviolet light or other light. This type of diaphragm mark 3 is more easily and accurately identified by a CCD (Charge-Coupled Device, or CCD image sensor), which can improve detection accuracy.

[0169] Of course, the colloid or coating used in this diaphragm marking 3 should not affect the performance of the battery cell.

[0170] In one embodiment of this application, the reserved area 101 includes a first reserved area 1011 and / or a second reserved area 1012. The first reserved area 1011 is located on the side of the negative electrode plate 2 where the negative electrode tab 2011 is provided, and the second reserved area 1012 is located on the side away from the negative electrode plate 2 where the negative electrode tab 2011 is provided. The first reserved area 1011 and / or the second reserved area 1012 are provided with a diaphragm mark 3.

[0171] See Figure 1 As shown, the reserved area 101 includes a first reserved area 1011 and / or a second reserved area 1012. Depending on the different product settings, the reserved area 101 may include only the first reserved area 1011, or only the second reserved area 1012, or both the first reserved area 1011 and the second reserved area 1012.

[0172] The first reserved area 1011 is located on the side of the negative electrode plate 2 where the negative electrode tab 2011 is provided, and the second reserved area 1012 is located on the side away from the negative electrode plate 2 where the negative electrode tab 2011 is provided. That is, in the first direction, the first reserved area 1011 and the second reserved area 1012 are located on both sides of the negative electrode plate 2, respectively.

[0173] Depending on the different product settings, the diaphragm mark 3 can be set only in the first reserved area 1011, or only in the second reserved area 1012, or both the first reserved area 1011 and the second reserved area 1012 can be set with the diaphragm mark 3.

[0174] In one embodiment of this application, in the first direction, the size of the first reserved area 1011 is c1, and the value of c1 is in the range of 3mm-5mm, and / or the size of the second reserved area 1012 is c2, and the value of c2 is in the range of 1.5mm-2mm.

[0175] See Figure 1 As shown, in one embodiment, in the first direction, the size of the first reserved area 1011 is c1, and the value of c1 is in the range of 3mm-5mm. For example, the value of c1 can be 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc.

[0176] See Figure 1 As shown, in one embodiment, in the first direction, the size of the second reserved area 1012 is c2, and the value of c2 is in the range of 1.5mm-2mm, for example: the value of c2 is 1.5mm, 1.7mm, 1.8mm, 1.9mm, 2mm, etc.

[0177] The size range of the first reserved area 1011 and the second reserved area 1012 mentioned above allows for the setting of the diaphragm mark 3 without affecting the coating of the positive and negative electrode sheets of the diaphragm, thus enabling the detection process of the diaphragm 1.

[0178] In one embodiment of this application, in the first direction, the distance between the diaphragm mark 3 and the edge of the first reserved area 1011 is d, and the value of the distance d is in the range of 1mm-2mm.

[0179] See Figure 2 As shown, in one embodiment, the distance between the diaphragm mark 3 and the edge of the first reserved area 1011 in the first direction is d. The value of distance d ranges from 1mm to 2mm, for example, the value of distance d can be 1mm, 1.1mm, 1.5mm, 1.8mm, 2mm, etc. The above-mentioned range of distance d allows the diaphragm mark 3 to be set without affecting the coating of the positive and negative electrode sheets by the diaphragm 1, thereby reducing the impact of the diaphragm mark 3 setting on the positive and negative electrode sheets.

[0180] In one embodiment of this application, the battery cell preparation method further includes inspecting the positive electrode roll and / or the negative electrode roll; the positive electrode roll includes a positive electrode foil 401, with positive electrode tabs 4011 spaced apart on one side of the positive electrode foil 401, and positive electrode foil markings 5 ​​are provided at the positive electrode tabs 4011, forming a positive electrode foil marking interval between adjacent positive electrode foil markings 5; the initial value of the positive electrode foil marking interval is a1, and the measured value of the positive electrode foil marking interval is a2; when the battery cell preparation method inspects the positive electrode roll, the battery cell preparation method includes: setting positive electrode foil at the positive electrode tabs 4011. Mark 5, at this point the value of the positive electrode foil marking interval is the initial value a1; the positive electrode active material is coated on the positive electrode foil 401 to obtain a positive electrode semi-finished product; the positive electrode semi-finished product is rolled to obtain a positive electrode roll; each positive electrode foil marking interval is detected to obtain the measured value a2 of the positive electrode foil marking interval; it is determined whether (a2-a1) / a1 is less than or equal to the second preset value; if a section of the positive electrode roll does not satisfy (a2-a1) / a1 being less than or equal to the second preset value, then a section of the positive electrode roll is cut; if so, then the positive electrode... The sheet roll is pre-cut and slit to obtain a positive electrode sheet; and / or, the negative electrode sheet roll includes a negative electrode foil 201, with negative electrode tabs 2011 spaced apart on one side of the negative electrode foil 201, and negative electrode foil markings 6 are provided at the negative electrode tabs 2011, forming a negative electrode foil marking interval between adjacent negative electrode foil markings 6; the initial value of the negative electrode foil marking interval is b1, and the measured value of the negative electrode foil marking interval is b2; when the battery cell preparation method detects the negative electrode sheet roll, the battery cell preparation method includes: setting negative electrode foil markings 6 at the negative electrode tabs 2011, at which time the value of the negative electrode foil marking interval is negative. The initial value b1 of the marking interval of the negative electrode foil; the negative electrode active material is coated on the negative electrode foil 201 to obtain a negative electrode semi-finished product; the negative electrode semi-finished product is rolled to obtain a negative electrode roll; the marking interval of each negative electrode foil is detected to obtain the measured value b2 of the marking interval of the negative electrode foil; it is determined whether (b2-b1) / b1 is less than or equal to the third preset value; if a part of the negative electrode roll does not satisfy (b2-b1) / b1 is less than or equal to the third preset value, then a part of the negative electrode roll is cut; if so, the negative electrode roll is pre-cut and cut to obtain the negative electrode 2.

[0181] In one embodiment, the battery cell preparation method further includes testing the positive electrode roll and / or negative electrode roll to detect abnormal tension in the positive electrode roll and / or negative electrode roll, thereby obtaining qualified positive electrode and negative electrode 2.

[0182] See Figure 2As shown, the positive electrode roll includes a positive electrode foil 401. Positive electrode tabs 4011 are spaced apart on one side of the positive electrode foil 401. The positive electrode tabs 4011 are spaced apart along a second direction, and positive electrode foil markings 5 ​​are provided at the positive electrode tabs 4011. In the second direction, a positive electrode foil marking interval is formed between adjacent positive electrode foil markings 5. The positive electrode foil marking interval refers to the distance between adjacent positive electrode foil markings 5 ​​in the second direction. The initial value of the positive electrode foil marking interval is a1, and the measured value of the positive electrode foil marking interval is a2.

[0183] The initial value a1 of the positive electrode foil marking interval refers to the initial distance between adjacent positive electrode foil markings 5 ​​when the positive electrode foil markings 5 ​​are set on the positive electrode foil. The measured value a2 of the positive electrode foil marking interval refers to the detection distance between adjacent positive electrode foil markings 5 ​​during the subsequent preparation of the positive electrode sheet.

[0184] When inspecting the positive electrode coil, the battery cell preparation method also includes:

[0185] Step 301: Set a positive electrode foil mark 5 at the positive electrode tab 4011. At this time, the value of the positive electrode foil mark interval is the initial value a1 of the positive electrode foil mark interval.

[0186] Along the second direction, a positive electrode foil mark 5 is provided on the positive electrode tab 4011 of the positive electrode foil 401, and adjacent positive electrode foil marks 5 are evenly spaced apart. The shape of the positive electrode foil mark 5 can be circular, triangular, etc., and this application does not limit it.

[0187] After the positive electrode foil mark 5 is set, a positive electrode foil mark interval is formed between adjacent positive electrode foil marks 5 in the second direction, and at this time the distance between adjacent positive electrode foil marks 5 is the initial value a1 of the positive electrode foil mark interval.

[0188] Step 302: Coat the positive electrode active material onto the positive electrode foil 401 to obtain a positive electrode semi-finished product.

[0189] A positive electrode active material slurry is coated on the surface of positive electrode foil 401 and dried to obtain a positive electrode semi-finished product.

[0190] Step 303: Roll the positive electrode semi-finished product to obtain a positive electrode coil.

[0191] The positive electrode semi-finished product is fed into a roller press for compaction, which densifies the positive electrode active material layer and yields a positive electrode coil.

[0192] Step 304: Detect each positive electrode foil marking interval to obtain the measured value a2 of the positive electrode foil marking interval.

[0193] During the preparation of the positive electrode sheet, due to factors such as the need for online preparation, the positive electrode sheet is prone to abnormal stress release. It is necessary to detect the stress release of the positive electrode sheet to determine if any abnormalities exist. Specifically, for the positive electrode sheet roll, the marking interval of each positive electrode foil is detected to obtain the measured value a2 of the marking interval.

[0194] Step 305: Determine whether (a2-a1) / a1 is less than or equal to the second preset value.

[0195] Based on the initial value a1 of the positive electrode foil marking interval and the measured value a2 of the positive electrode foil marking interval, calculate whether (a2-a1) / a1 is less than or equal to a second preset value. The second preset value is a pre-set error value. In one embodiment, the value of the second preset value ranges from 0.5% to 0.8%, for example, it can be 0.5%, 0.6%, 0.7%, 0.8%, etc.

[0196] Step 306: If a portion of the positive electrode coil does not satisfy (a2-a1) / a1 being less than or equal to the second preset value, then the portion of the positive electrode coil is cut.

[0197] If a portion of the positive electrode coil does not satisfy (a2-a1) / a1 being less than or equal to the second preset value, i.e., greater than the second preset value, then the portion of the positive electrode coil is cut.

[0198] In one embodiment, the stress release of the cut-off positive electrode coil portion can be promoted by secondary unwinding until the requirements are met.

[0199] Step 307: If so, pre-cut and cut the positive electrode roll to obtain the positive electrode sheet.

[0200] If a portion of the positive electrode coil satisfies (a2-a1) / a1 being less than or equal to a second preset value, then the positive electrode coil can be pre-cut and slit to obtain the positive electrode sheet. In subsequent processes, the positive electrode sheet is wound with the separator coil and the negative electrode sheet to form a battery cell.

[0201] See Figure 2 As shown, the negative electrode roll includes a negative electrode foil 201. Negative electrode tabs 2011 are spaced apart on one side of the negative electrode foil 201. The negative electrode tabs 2011 are spaced apart along a second direction, and negative electrode foil markings 6 are provided at the negative electrode tabs 2011. In the second direction, a negative electrode foil marking interval is formed between adjacent negative electrode foil markings 6. The negative electrode foil marking interval refers to the distance between adjacent negative electrode foil markings 6 in the second direction. The initial value of the negative electrode foil marking interval is b1, and the measured value of the negative electrode foil marking interval is b2.

[0202] The initial value b1 of the negative electrode foil marking interval refers to the initial distance between adjacent negative electrode foil markings 6 when the negative electrode foil markings 6 are set on the negative electrode foil. The measured value b2 of the negative electrode foil marking interval refers to the detection distance between adjacent negative electrode foil markings 6 during the subsequent preparation of the negative electrode sheet.

[0203] When inspecting the negative electrode coil, the battery cell preparation method also includes:

[0204] Step 401: Set a negative electrode foil mark 6 at the negative electrode tab 2011. At this time, the value of the negative electrode foil mark interval is the initial value b1 of the negative electrode foil mark interval.

[0205] Along the second direction, a negative electrode foil mark 6 is provided at the negative electrode tab 2011 of the negative electrode foil 201, and adjacent negative electrode foil marks 6 are evenly spaced apart. The shape of the negative electrode foil mark 6 can be circular, triangular, etc., and this application does not limit it.

[0206] After the negative electrode foil mark 6 is set, a negative electrode foil mark interval is formed between adjacent negative electrode foil marks 6 in the second direction, and the distance between adjacent negative electrode foil marks 6 is the initial value b1 of the negative electrode foil mark interval.

[0207] Step 402: Coat the negative electrode active material onto the negative electrode foil 201 to obtain a negative electrode sheet semi-finished product.

[0208] A negative electrode active material slurry is coated on the surface of the negative electrode foil 201 and dried to obtain a negative electrode sheet semi-finished product.

[0209] Step 403: Roll the negative electrode semi-finished product to obtain a negative electrode coil.

[0210] The negative electrode sheet is fed into a roller press for compaction, which densifies the negative electrode active material layer to obtain the negative electrode sheet roll.

[0211] Step 404: Detect the marking interval of each negative electrode foil to obtain the measured value b2 of the negative electrode foil marking interval.

[0212] During the preparation of the negative electrode sheet, due to factors such as the need for online preparation, the negative electrode sheet is prone to abnormal stress release. It is necessary to detect the stress release of the negative electrode sheet to determine if any abnormalities exist. Specifically, for the negative electrode sheet roll, the marking interval of each negative electrode foil is detected to obtain the measured value a2 of the marking interval of the negative electrode foil.

[0213] Step 405: Determine whether (b2-b1) / b1 is less than or equal to the third preset value.

[0214] Based on the initial value b1 of the negative electrode foil marking interval and the measured value a2 of the negative electrode foil marking interval, calculate whether (b2-b1) / b1 is less than or equal to a third preset value. The third preset value is a pre-set error range. In one embodiment, the value range of the third preset value is 0.1%-0.2%, for example, the value of the third preset value can be 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, etc.

[0215] Step 406: If a portion of the negative electrode coil does not satisfy (b2-b1) / b1 being less than or equal to the third preset value, then the portion of the negative electrode coil is cut.

[0216] If a portion of the negative electrode roll does not satisfy (b2-b1) / b1 being less than or equal to the third preset value, i.e., greater than the third preset value, then the portion of the negative electrode roll is cut.

[0217] In one embodiment, the stress release of the cut-off negative electrode sheet roll portion can be promoted by secondary unwinding until the requirements are met.

[0218] Step 407: If so, pre-cut and cut the negative electrode roll to obtain negative electrode 2.

[0219] If a portion of the negative electrode coil satisfies (b2-b1) / b1 being less than or equal to a third preset value, the negative electrode coil can be pre-cut and slit to obtain negative electrode 2. In subsequent processes, negative electrode 2 is wound with a finished separator coil and a positive electrode coil to form a battery cell.

[0220] This application also provides a battery cell, which includes: a positive electrode, a negative electrode 2, and a separator 1. The separator 1 is disposed between the positive electrode and the negative electrode 2, and the separator 1 and the negative electrode 2 are partially overlapped. In a first direction, the size of the separator 1 is larger than the size of the negative electrode 2. The part of the separator 1 that does not overlap with the negative electrode 2 is a reserved area 101. In the first direction, the reserved area 101 is located on at least one side of the negative electrode 2, and at least a portion of the reserved area 101 is provided with a plurality of spaced separator marks 3.

[0221] The separator 1 of this battery cell is prepared by the above-mentioned battery cell preparation method, which can obtain a qualified separator 1 that meets the requirements, as well as qualified positive electrode and negative electrode 2. This can reduce the risk of micro-short circuit and thermal runaway inside the cell, improve the safety and reliability of the battery cell, and thus significantly improve the product quality of the battery cell.

[0222] This application also provides a battery device including the above-mentioned battery cell, and the battery device includes one or more of the following: battery module, battery pack, and energy storage battery.

[0223] This application also provides an electrical device, including the aforementioned battery device, which provides electrical energy to the electrical device. The battery device serves as the power source for the electrical device, which can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc.

[0224] This application also provides an energy storage device, including the aforementioned battery device, which is used to store electrical energy for the energy storage device. The battery device serves as the power source for the energy storage device, which can be, but is not limited to, an energy storage container, an energy storage cabinet, an energy storage power station, an energy storage battery pack, or a portable energy storage system.

[0225] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0226] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a single battery cell, characterized in that, This includes testing the diaphragm (1); The diaphragm (1) is partially overlapped with the negative electrode plate (2). In the first direction, the size of the diaphragm (1) is larger than the size of the negative electrode plate (2). The part of the diaphragm (1) that does not overlap with the negative electrode plate (2) is a reserved area (101). In the first direction, the reserved area (101) is located on at least one side of the negative electrode plate (2). At least a portion of the reserved area (101) is provided with a plurality of spaced diaphragm marks (3). In the second direction, a first diaphragm mark interval is formed between adjacent diaphragm marks (3). The initial value of the first separator marking interval is L1, and the measured value of the first separator marking interval is L2; ​​the battery cell preparation method includes: Determine whether (L2-L1) / L1 is less than or equal to the first preset value; If a portion of the diaphragm (1) does not satisfy (L2-L1) / L1 being less than or equal to the first preset value, then the portion of the diaphragm (1) is cut or discarded. If so, then the diaphragm (1) is qualified.

2. The method for preparing a battery cell according to claim 1, characterized in that, The method also includes inspecting the first diaphragm roll, and the qualified first diaphragm roll forms the diaphragm (1). The battery cell preparation method includes: Obtain the second diaphragm roll; The diaphragm mark (3) is set on the second diaphragm roll. At this time, a second diaphragm mark interval is formed between adjacent diaphragm marks (3) in the second direction. The initial value of the second diaphragm mark interval is L3, which is equal to the initial value of the first diaphragm mark interval L1. The second diaphragm roll is pre-cut to obtain the third diaphragm roll; The third diaphragm roll is left to stand for a time T. The third diaphragm roll is cut to obtain the first diaphragm roll; Each of the second diaphragm marking intervals is detected to obtain the measured value L4 of the second diaphragm marking interval; Determine whether (L4-L3) / L3 is less than or equal to the first preset value; If a portion of the first diaphragm roll does not satisfy (L4-L3) / L3 being less than or equal to the first preset value, then the portion of the first diaphragm roll is cut. If so, the diaphragm (1) is obtained.

3. The method for preparing a battery cell according to claim 2, characterized in that, In the step of obtaining the second diaphragm roll, the tension borne by the second diaphragm roll is 100N-200N; And / or, in the step of pre-slitting the second diaphragm roll to obtain the third diaphragm roll, the tension borne by the second diaphragm roll and the third diaphragm roll is 50N-100N; And / or, in the step of cutting the third diaphragm roll to obtain the first diaphragm roll, the tension borne by the first diaphragm roll and the third diaphragm roll is 300N-400N.

4. The method for preparing a battery cell according to claim 1, characterized in that, Before the step of determining whether (L2-L1) / L1 is less than or equal to a first preset value, the method further includes: The diaphragm (1), the positive electrode, and the negative electrode (2) are wound together; During the winding process, each of the first diaphragm mark intervals is detected to obtain the measured value L2 of the first diaphragm mark interval; And / or, after the step of determining whether (L2-L1) / L1 is less than or equal to a first preset value, the method further includes: if so, obtaining the battery cell.

5. The method for preparing a battery cell according to claim 4, characterized in that, In the step of winding the diaphragm (1), the positive electrode and the negative electrode (2), the tension borne by the diaphragm (1) is 400N-500N.

6. The method for preparing a battery cell according to claim 1, characterized in that, The diaphragm mark (3) is a colored mark or the diaphragm mark (3) is colored under a preset light.

7. The method for preparing a battery cell according to claim 1, characterized in that, The first preset value ranges from 0.3% to 5%.

8. The method for preparing a battery cell according to claim 1, characterized in that, The reserved area (101) includes a first reserved area (1011) and / or a second reserved area (1012). The first reserved area (1011) is located on the side where the negative electrode tab (2) is provided, and the second reserved area (1012) is located on the side away from the negative electrode tab (2) where the negative electrode tab (2011) is provided. The first reserved area (1011) and / or the second reserved area (1012) are provided with the diaphragm mark (3).

9. The method for preparing a battery cell according to claim 8, characterized in that, In the first direction, the size of the first reserved area (1011) is c1, and the value of c1 is in the range of 3mm-5mm, and / or the size of the second reserved area (1012) is c2, and the value of c2 is in the range of 1.5mm-2mm.

10. The method for preparing a battery cell according to claim 8, characterized in that, In the first direction, the distance between the diaphragm mark (3) and the edge of the first reserved area (1011) is d, and the value of the distance d is in the range of 1mm-2mm.

11. The method for preparing a battery cell according to any one of claims 1-10, characterized in that, The battery cell preparation method further includes testing the positive electrode roll and / or negative electrode roll; The positive electrode roll includes a positive electrode foil (401), and positive electrode tabs (4011) are spaced apart on one side of the positive electrode foil (401). A positive electrode foil mark (5) is provided at each positive electrode tab (4011), and a positive electrode foil mark interval is formed between adjacent positive electrode foil marks (5). The initial value of the positive electrode foil mark interval is a1, and the measured value of the positive electrode foil mark interval is a2. When the battery cell preparation method detects the positive electrode roll, the battery cell preparation method includes: The positive electrode foil mark (5) is set at the positive electrode tab (4011), and the value of the positive electrode foil mark interval is the initial value a1 of the positive electrode foil mark interval; A positive electrode active material is coated on the positive electrode foil (401) to obtain a positive electrode sheet semi-finished product; The positive electrode semi-finished product is rolled to obtain the positive electrode coil; Each of the positive electrode foil marking intervals is detected to obtain the measured value a2 of the positive electrode foil marking interval; Determine whether (a2-a1) / a1 is less than or equal to the second preset value; If a portion of the positive electrode coil does not satisfy (a2-a1) / a1 being less than or equal to the second preset value, then the portion of the positive electrode coil is cut. If so, the positive electrode roll is pre-cut and cut to obtain the positive electrode sheet; And / or, The negative electrode roll includes a negative electrode foil (201), and negative electrode tabs (2011) are spaced apart on one side of the negative electrode foil (201). Negative electrode foil markings (6) are provided at the negative electrode tabs (2011), and negative electrode foil marking intervals are formed between adjacent negative electrode foil markings (6). The initial value of the negative electrode foil marking interval is b1, and the measured value of the negative electrode foil marking interval is b2. When the battery cell preparation method detects the negative electrode roll, the battery cell preparation method includes: The negative electrode foil mark (6) is set at the negative electrode tab (2011), and the value of the negative electrode foil mark interval is the initial value b1 of the negative electrode foil mark interval; A negative electrode active material is coated on the negative electrode foil (201) to obtain a negative electrode sheet semi-finished product; The negative electrode semi-finished product is rolled to obtain the negative electrode coil; Each of the negative electrode foil marking intervals is detected to obtain the measured value b2 of the negative electrode foil marking interval; Determine whether (b2-b1) / b1 is less than or equal to the third preset value; If a portion of the negative electrode coil does not satisfy (b2-b1) / b1 being less than or equal to the third preset value, then the portion of the negative electrode coil is cut. If so, the negative electrode roll is pre-cut and cut to obtain the negative electrode (2).

12. The method for preparing a battery cell according to claim 11, characterized in that, The second preset value ranges from 0.5% to 0.8%, and the third preset value ranges from 0.1% to 0.2%.

13. A single battery cell, characterized in that, The battery cell includes: Positive electrode sheet; Negative electrode plate (2); A diaphragm (1) is disposed between the positive electrode and the negative electrode (2). The diaphragm (1) partially overlaps with the negative electrode (2). In a first direction, the size of the diaphragm (1) is larger than the size of the negative electrode (2). The portion of the diaphragm (1) that does not overlap with the negative electrode (2) is a reserved area (101). In the first direction, the reserved area (101) is located on at least one side of the negative electrode (2). At least a portion of the reserved area (101) is provided with a plurality of spaced diaphragm marks (3).

14. A battery device, characterized in that, The battery device includes one or more of the following: battery cell as described in claim 13, battery device including battery module, battery pack, energy storage battery.

15. An electrical appliance, characterized in that, Includes the battery device as described in claim 14, the battery device being used to provide electrical energy to the electrical device.

16. An energy storage device, characterized in that, Includes the battery device as described in claim 14, the battery device being used to store electrical energy for the energy storage device.

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