Electrode plate, electrode core, battery and manufacturing method

Abstract

The invention relates to an electrode plate, an electrode core, a battery and a manufacturing method. The electrode sheet includes: a coating region; the first tab area is connected to the coating area and is provided with a folded edge far away from the coating area; the second tab region is connected to the folded edge and is overlapped in the first tab region; and the width of the second tab area is smaller than that of the first tab area at any distance position of the opposite folded edges. The electrode plate is favorable for reducing the voltage drop of the assembled battery in unit time.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to electrode sheets, pole cores, batteries and manufacturing methods. Background Art

[0002] The manufacturing process of power batteries generally includes: assembling the positive and negative electrodes into a core by lamination or winding, sealing it into the shell by ultrasonic welding, laser welding and other processes, and finally injecting electrolyte, and obtaining a battery cell after processes such as formation, aging, and capacity separation. With the continuous development of battery technology, higher requirements are also put forward for various indicators of power batteries. Among them, the performance of the battery cell determines the performance and safety of the battery during use.

[0003] The laminated pole core is formed by stacking the positive pole piece, the negative pole piece and the diaphragm in sequence, and the size of the diaphragm is larger than the size of the negative pole, so that the diaphragm can completely cover the negative pole; the size of the negative pole is larger than the size of the positive pole, so that the negative pole can completely cover the positive pole. In order to avoid interference between the pole ear and the injection hole and the explosion-proof valve, thereby affecting the safety of the battery cell, whether it is the top pole ear of the square aluminum battery cell or the side pole ear of the short knife battery cell, the positive pole piece or the negative pole piece is punched out of the positive pole ear and the negative pole ear by hardware die cutting or laser die cutting before stacking, that is, the area of ​​the positive pole ear and the negative pole ear is limited by the overall structural design of the battery cell top cover.

[0004] When designing and manufacturing batteries with higher charging rates, the positive and negative pole ears need to withstand greater currents, and the current flow area of ​​the ear is limited by the top cover, which makes it very easy for the ear to have excessive temperature rise during fast charging, greatly limiting the fast charging performance of the battery cell, and also causing major safety hazards in the long-term use of the battery cells. When enhancing the current flow capacity of the ear, it was found that the voltage dropped too quickly and the battery self-discharge rate was too high. Summary of the invention

[0005] Based on this, it is necessary to provide an electrode sheet, an electrode core, a battery and a manufacturing method to address at least one of the above problems.

[0006] On the one hand, the present application provides an electrode sheet, which includes: a coating area; a first pole lug area, connected to the coating area and having a folded edge away from the coating area; and a second pole lug area, connected to the folded edge and overlapping in the first pole lug area; at any distance position relative to the folded edge, the width of the second pole lug area is smaller than the width of the first pole lug area.

[0007] By setting the second pole lug area to overlap the first pole lug area, the flow area of ​​the first pole lug area to the outside of the electrode sheet is increased, the flow capacity is enhanced, and then the heat generation of the first pole lug area is reduced; the appropriate flow capacity can be configured by designing the size of the second pole lug area; the width of the second pole lug area is relatively small, ensuring that it falls completely within the first pole lug area during the folding process, and is easy to manufacture; collision and interference during electrode sheet assembly are avoided, and reliable execution of processes such as pole lug welding and shelling is guaranteed; redundancy of the edge of the second pole lug area relative to the first pole lug area is avoided, which is beneficial to reducing the voltage drop (K value) per unit time of the assembled battery; the second pole lug part and the third pole lug part are easier to keep flat, and the stacking effect is good; while ensuring the effect, it is beneficial to avoid the excess weight of the pole lug of the electrode sheet, which is beneficial to improving the manufacturing yield of the electrode sheet.

[0008] In some embodiments, the first pole ear region includes a first pole ear portion and a second pole ear portion, and the coating region, the first pole ear portion and the second pole ear portion are connected in sequence; the width L0 of the coating region, the width L1 of the first pole ear portion and the width L2 of the second pole ear portion satisfy the relationship: L0≥L1>L2.

[0009] With such arrangement, the second pole ear portion ensures reliable electrical connection in a compact installation environment, and the wider first pole ear portion can increase the flow area of ​​electrons from the coating area to the second pole ear portion, thereby reducing heat generation of the pole ear.

[0010] In some embodiments, the width of the second pole ear portion is smallest at the folded edge position.

[0011] With such arrangement, the shape of the second pole ear ensures both the current carrying capacity and the installation and connection capabilities.

[0012] In some embodiments, the angle of the corner of the second pole tab portion at the folded edge is greater than the angle of the corresponding corner of the second pole tab region at the folded edge.

[0013] With this arrangement, there is no obvious step difference between the second pole ear portion and the second pole ear region, and the second pole ear region can be completely placed within the first pole ear region after being folded, which ensures the convenience of processing and manufacturing and the performance of the electrode sheet.

[0014] In some embodiments, the second pole lug region overlaps within the second pole lug portion. Exemplarily, the second pole lug region partially overlaps within the first pole lug portion.

[0015] Such arrangement makes processing and manufacturing easy.

[0016] In some embodiments, the height of the first pole lug portion is less than the height of the second pole lug portion. Exemplarily, the height H1 of the first pole lug portion and the height H2 of the second pole lug portion satisfy: 0.05×H2≤H1≤0.5×H2. Exemplarily, the area of ​​the second pole lug region overlapping the second pole lug portion is 60% to 90% of the area of ​​the second pole lug portion.

[0017] With such arrangement, the second pole ear portion can have a sufficient height and area to ensure assembly; when the second pole ear region only overlaps within the second pole ear portion, a sufficient flow area can still be ensured.

[0018] On the other hand, the present application provides a method for manufacturing an electrode sheet, which includes: forming an electrode sheet precursor, the electrode sheet precursor including a coating area, a first pole lug area connected to the coating area and having a folded edge away from the coating area, and a second pole lug area connected to the folded edge, wherein at any position of the same distance relative to the folded edge, the width of the second pole lug area is smaller than the width of the first pole lug area; and folding the second pole lug area around the folded edge into the first pole lug area.

[0019] The method for manufacturing an electrode sheet of the present application is easy to implement, avoids large-scale modification of existing production lines, and is capable of manufacturing the aforementioned electrode sheet.

[0020] On the other hand, the present application provides a method for manufacturing an electrode core, the method for manufacturing an electrode core comprising: the steps of the aforementioned method for manufacturing an electrode sheet; and before the folding step, stacking a plurality of electrode sheet precursors.

[0021] The method for manufacturing a pole core of the present application is reliable to execute and can manufacture the aforementioned pole core, including the aforementioned electrode sheet.

[0022] In another aspect, the present application provides a pole core, which includes the aforementioned electrode sheet. Exemplarily, the pole core includes an electrode sheet made by the aforementioned method for making an electrode sheet. Exemplarily, the pole core is made according to the aforementioned method for making a pole core.

[0023] The pole core of the present application has good assembly capability, good current carrying capacity, and low self-discharge rate.

[0024] In yet another aspect, the present application provides a battery, comprising the aforementioned pole core.

[0025] The battery of the present application is safe to use, has little leakage, and has a long storage time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic top view of an electrode sheet according to one or more embodiments;

[0027] Figure 2is a schematic front view of an electrode sheet according to one or more embodiments;

[0028] Figure 3 is a schematic structural diagram of an electrode sheet precursor according to one or more embodiments;

[0029] Figure 4 is a schematic structural diagram of an electrode sheet precursor according to one or more embodiments;

[0030] Figure 5 is a schematic structural diagram of an electrode sheet precursor according to one or more embodiments;

[0031] Figure 6 is a schematic structural diagram of an electrode sheet precursor according to one or more embodiments;

[0032] Figure 7 is a schematic flowchart of a method for manufacturing an electrode sheet according to one or more embodiments;

[0033] Figure 8 is a schematic flowchart of a method for manufacturing a pole core according to one or more embodiments;

[0034] Fig. 9 is a schematic structural diagram of a pole core according to one or more embodiments;

[0035] Fig.10 is a schematic flow chart of a method for manufacturing a pole core according to one or more embodiments;

[0036] Fig.11 is a schematic structural block diagram of a battery according to one or more embodiments;

[0037] Fig.12 It is a structural schematic diagram of Comparative Example 1;

[0038] Fig.13 It is a structural schematic diagram of Comparative Example 2;

[0039] Fig.14 It is a structural schematic diagram of Comparative Example 3;

[0040] Fig.15 It is the lug temperature rise curve diagram of Comparative Example 1, Example 1, Example 2 and Example 3;

[0041] Fig.16 It is the lug temperature rise curve of Example 3, Comparative Example 2 and Comparative Example 3.

[0042] Description of reference numerals: 10, coating area; 20, first pole lug area; 30, second pole lug area;

[0043] 1. first pole ear; 11. first side; 12. second side; 2. second pole ear; 21. folded edge; 22. third side; 23. fourth side; 24. first surface; 3. third pole ear; 31. fifth side; 32. sixth side; 33. end; 34. second surface;

[0044] 100, pole core; 110, electrode sheet; 1100, electrode sheet precursor; 200, battery; 210, top cover; 220, shell. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments of the following disclosed implementation methods.

[0046] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "perpendicular", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0047] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0048] In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. Exemplarily, the first side may also be referred to as the second side, and the second side may also be referred to as the first side. In the description of this application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0049] In this application, unless otherwise clearly specified and limited, the terms "connected", "connected", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a flexible connection, or a rigid connection along at least one direction; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or directly connected with the presence of an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. The terms "install", "set", "fixed", etc. can be broadly understood as connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0050] The terms "layer" and "region" used in this application refer to a material portion that includes a certain area and has a certain thickness. The layer can extend horizontally, vertically and / or along a tapered surface. A layer can be an area of ​​a uniform or non-uniform continuous structure, and its thickness perpendicular to the extension direction may not be greater than the thickness of the continuous structure. A layer can include multiple layers, which can be multiple layers stacked or multiple layers extending discretely. The shapes of various areas and layers in the accompanying drawings and their relative sizes and positional relationships are only exemplary, and may actually deviate due to manufacturing tolerances or technical limitations, and the design can be adjusted according to actual needs.

[0051] refer to Figure 1 , Figure 1 1 shows an electrode sheet in the present application. In an exemplary embodiment, the electrode sheet 110 includes a coating area 10, a first pole lug area 20 and a second pole lug area 30. The first pole lug area 20 and the second pole lug area 30 are used to form a pole lug suitable for external connection. The electrode sheet 110 is a laminated electrode, which can be used as a positive pole sheet or a negative pole sheet.

[0052] The size of the electrode sheet 110 can be designed according to the requirements. For the convenience of description, a spatial rectangular coordinate system XYZ is set. For example, the shape of the coating area 10 along the XZ plane is roughly rectangular, the size of the coating area 10 along the X-axis direction can be called the width, and the size along the Z-axis direction can be called the height. Figure 2 As shown, the dimension along the Y-axis direction can be called thickness.

[0053] Combination Figure 2 As shown, the first pole lug region 20 is connected to the coating region 10, and the two can be arranged along the Z-axis direction. The first pole lug region 20 has a folded edge 21, which is an edge away from the coating region 10. Specifically, the first pole lug region 20 extends back to the coating region 10, and the folded edge 21 is the edge of the first pole lug region 20 facing away from the coating region 10 along the extension direction.

[0054] The second pole lug area 30 is connected to the first pole lug area 20. Specifically, the second pole lug area 30 is connected to the folded edge 21. The coating area 10, the first pole lug area 20 and the second pole lug area 30 are arranged in sequence, and the second pole lug area 30 is folded back relative to the folded edge 21 of the first pole lug area 20. The second pole lug area 30 overlaps the first pole lug area 20. Figure 1 As shown, at any distance relative to the folded edge 21, the width of the second tab region 30 is less than the width of the first tab region 20. It can be understood that at the folded edge 21, the width of the second tab region 30 can be considered to be the same as the width of the first tab region 20.

[0055] Exemplarily, at any distance relative to the folded edge 21, at least one of the two sides of the second tab region 30 is spaced from the side of the first tab region 20, for example, both sides of the second tab region 30 are spaced. The end 33 of the second tab region 30 is flush with the side of the coating region 10 or spaced.

[0056] When the electrode sheet 110 is used in the electrode core 100, for example Fig. 9 , the performance of the coating area 10 can be higher, and then by setting the second pole ear area 30 in the pole ear structure to overlap the first pole ear area 20, the flow area of ​​the first pole ear area 20 to the outside of the electrode sheet 110 can be increased by 100%, the flow capacity is enhanced, and the heat generation of the first pole ear area 20 is reduced. At the same time, the narrower design of the second pole ear area 30 avoids the redundancy of the second pole ear area 30 relative to the edge of the first pole ear area 20, which is conducive to reducing the assembled Fig.11 The voltage drop per unit time (K value) of the battery 200 is shown.

[0057] In the electrode sheet 110 provided in the embodiment of the present application, the size of the second pole lug region 30 can be designed and adjusted, and then the overlapping area with the first pole lug region 20 is controlled, and the electrode sheet 110 can have a suitable current flow capacity.

[0058] In some embodiments, the first pole lug region 20 includes a first pole lug portion 1 and a second pole lug portion 2. The coating region 10, the first pole lug portion 1 and the second pole lug portion 2 are connected in sequence. The second pole lug portion 2 may have a folded edge 21, and then the third pole lug portion 3 of the second pole lug region 30 may be connected to the folded edge 21.

[0059] The width of the second pole ear portion 2 may be smaller than the width of the coating area 10 to ensure the installation and fit of the second pole ear portion 2 in the battery 200. Along the X-axis direction, the second pole ear portion 2 may be offset relative to the coating area 10, and the distances between the two sides of the second pole ear portion 2 and the corresponding sides of the coating area 10 may be different. The third pole ear portion 3 is arranged along the folded edge 21 of the second pole ear portion 2. The folded third pole ear portion 3 and the second pole ear portion 2 can avoid collision and interference when the electrode sheet 110 is assembled, ensuring reliable execution of the processes such as pole ear welding and shell insertion.

[0060] The width L0 of the coating area 10, the width L1 of the first pole ear portion 1, and the width L2 of the second pole ear portion 2 satisfy the relationship: L0 ≥ L1 > L2. The second pole ear portion 2 can ensure reliable electrical connection in a compact installation environment. The first pole ear portion 1 is connected between the second pole ear portion 2 and the coating area 10. The width of the first pole ear portion 1 is greater than the width of the second pole ear portion 2 and less than or equal to the width of the coating area 10, which increases the flow area between the second pole ear portion 2 and the coating area 10, and greatly reduces the heat generation of the pole ear. Exemplarily, the width of the second pole ear portion 2 is greater than half the width of the coating area 10.

[0061] Optionally, the position of the first pole ear portion 1 relative to the coating area 10 along the X-axis direction can be approximately in the middle; when the width of the first pole ear portion 1 is smaller than the width of the coating area 10, it can also be relatively offset with the second pole ear portion 2. The width and height of the first pole ear portion 1 can be designed and adjusted to flexibly control the flow area and length of the first pole ear portion 1, thereby adjusting the flow capacity of the pole ear.

[0062] Combination Figures 3 to 6 As shown, the electrode sheet 110 can be obtained by folding an electrode sheet precursor 1100 . Figures 3 to 6 Several electrode sheet precursors 1100 of different shapes are shown. When folding along the folded edge 21, the second tab region 30 may have some errors relative to the theoretical position. The second tab region 30 has a smaller width, which helps to ensure that it completely falls within the first tab region 20 during the folding process, and the electrode sheet 110 is easy to manufacture.

[0063] like Figure 3 As shown, from the coating area 10 along the Z-axis direction, the first pole ear portion 1, the second pole ear portion 2 and the third pole ear portion 3 are connected in sequence. The first side edge 11 of the first pole ear portion 1 is spaced from the corresponding side edge of the coating area 10, and the second side edge 12 of the first pole ear portion 1 is spaced from the corresponding side edge of the coating area 10. The third side edge 22 of the second pole ear portion 2 is located inside the first side edge 11 along the X-axis direction and has a gap, and the fourth side edge 23 is located inside the second side edge 12 and has a gap.

[0064] The width of the second pole ear portion 2 is smallest at the folded edge 21. Optionally, the second pole ear portion 2 has a trapezoidal shape, and the two sides of the trapezoid can be straight sides or arcs with certain convex or concave. The shape of the second pole ear portion 2 ensures both the current capacity and the installation and connection capabilities.

[0065] The angle θ1 of the first corner of the second pole ear portion 2 at the folded edge 21 is greater than the angle θ2 of the corresponding second corner of the second pole ear region 30 at the folded edge 21. The second pole ear portion 2 may be an isosceles trapezoid. In other embodiments, the shape of the second pole ear portion 2 itself may also be asymmetrical. Figure 3 As shown, the first angle is an obtuse angle; the second angle may also be an obtuse angle, and in other embodiments may also be a right angle. At any position of the same distance relative to the folded edge 21, the width of the second pole ear area 30 is less than the width of the first pole ear area 20, and the folded edge 21 can be equal and flush. After folding, the fifth side 31 is located inside the third side 22 along the X-axis direction, and the sixth side 32 is located inside the fourth side 23. There is no obvious step difference between the second pole ear portion 2 and the third pole ear portion 3, and it can ensure that the second pole ear area 30 falls completely within the first pole ear area 20 after folding, which not only ensures the convenience of processing and manufacturing, but also ensures the performance of the electrode sheet 110.

[0066] Exemplarily, the width L1 of the first pole ear portion 1 is 1.3 times the width L2 of the second pole ear portion 2 , wherein the width L2 may be the widest part of the second pole ear portion 2 ; meanwhile, the width L1 of the first pole ear portion 1 is 0.8 times the width L0 of the coating area 10 .

[0067] Along the Z-axis direction, the height of the second pole lug region 30 may be less than the height of the first pole lug region 20. Optionally, the second pole lug region 30 overlaps within the second pole lug portion 2; the second pole lug region 30 may also partially overlap within the first pole lug portion 1. Figure 3 The electrode sheet precursor 1100 shown is easy to process and manufacture, and the crease is easy to control to be the folded edge 21 when folded.

[0068] The height of the first pole ear portion 1 may be less than the height of the second pole ear portion 2. With this arrangement, the second pole ear portion may have sufficient height and area to ensure assembly; when the second pole ear region only overlaps within the second pole ear portion, sufficient flow area can still be ensured. Exemplarily, the height H1 of the first pole ear portion 1 and the height H2 of the second pole ear portion 2 may satisfy: 0.05×H2≤H1≤0.5×H2. For example, the height H2 of the second pole ear portion 2 is 26 mm; the height H1 of the first pole ear portion 1 may be 0.2 times the height H2 of the second pole ear portion 2. The height H3 of the third pole ear portion 3 may be equal to the height H2 of the second pole ear portion 2. After the second pole ear region 30 is folded to the first pole ear region 20, the end 33 may overlap the edge of the second pole ear portion 2.

[0069] Exemplarily, the first pole lug portion 1 , the second pole lug portion 2 and the third pole lug portion 3 are made of the same material and may have the same thickness. After folding, the first surface 24 of the second pole lug portion 2 may be attached to the second surface 34 of the third pole lug portion 3 .

[0070] In other embodiments, the third pole lug portion 3 may be higher in height, and then after folding, it may overlap with the first pole lug portion 1. The width at the end 33 may be greater than the width of the second pole lug portion 2, which helps to increase the flow area.

[0071] like Figure 4 As shown, the electrode tab of the electrode sheet precursor 1100 includes a first electrode tab portion 1, a second electrode tab portion 2, and a third electrode tab portion 3 arranged in sequence. The width of the first electrode tab portion 1 may be 1.6 times the width of the second electrode tab portion 2. The width of the first electrode tab portion 1 may be 0.8 times the width of the coating area 10. The height of the first electrode tab portion 1 may be 0.15 times the height of the second electrode tab portion 2, and the height of the second electrode tab portion 2 may be 26 mm.

[0072] The angle θ1 of the first angle of the second pole ear portion 2 at the folded edge 21 and the angle θ2 of the second angle corresponding to the third pole ear portion 3 at the folded edge 21 are complementary angles, and the side of the third pole ear portion 3 is connected to the side of the second pole ear portion 2 in a straight line. Exemplarily, θ1 is an obtuse angle and θ2 is an acute angle. For example, θ1 is 94° and θ2 is 86°. The height of the third pole ear portion 3 can be equal to the height of the second pole ear portion 2.

[0073] The tab shape of the electrode sheet precursor 1100 is easy to manufacture, and the second tab region 30 can be overlapped in the first tab region 20 after being folded along the folded edge 21 .

[0074] like Figure 5 As shown, the electrode tab of the electrode sheet precursor 1100 includes a first electrode tab portion 1, a second electrode tab portion 2 and a third electrode tab portion 3 which are arranged in sequence. Figure 4 The electrode sheet precursor 1100 shown, Figure 5 In the electrode sheet precursor 1100 shown, the width of the first electrode ear portion 1 is the same as the width of the coating area 10 , and both side edges of the first electrode ear portion 1 are flush with both side edges of the coating area 10 .

[0075] like Figure 6 As shown, the electrode tab of the electrode sheet precursor 1100 includes a first electrode tab portion 1, a second electrode tab portion 2, and a third electrode tab portion 3 arranged in sequence. The width of the first electrode tab portion 1 is the same as the width of the coating area 10, and the two sides of the first electrode tab portion 1 are flush with the two sides of the coating area 10. The width of the first electrode tab portion 1 is 1.6 times the width of the second electrode tab portion 2. The height of the first electrode tab portion 1 is 0.2 times the height of the second electrode tab portion 2, wherein the height of the second electrode tab portion 2 is 26 mm.

[0076] The first angle of the second pole ear portion 2 at the folded edge 21 may be an obtuse angle, for example, the value of θ1 is 94°. The angle θ2 of the corresponding second angle of the third pole ear portion 3 may be 76°. At the folded edge 21, the third pole ear portion 3 is as wide as the second pole ear portion 2. The dimension of the third pole ear portion 3 along the Z-axis direction is also 26 mm.

[0077] like Figure 7 As shown, the present application provides a method for manufacturing an electrode sheet. In an exemplary embodiment, the method 1000 for manufacturing an electrode sheet includes step S110 and step S120.

[0078] Combination Figures 3 to 6 , step S110, forming an electrode sheet precursor 1100. The electrode sheet precursor 1100 includes a coating area 10, a first pole lug area 20 connected to the coating area 10 and having a folded edge 21 away from the coating area 10, and a second pole lug area 30 connected to the folded edge 21. At any position of the same distance relative to the folded edge 21, the width of the second pole lug area 30 is less than the width of the first pole lug area 20. At the folded edge 21, the second pole lug area 30 and the first pole lug area 20 can be flush with each other with equal width.

[0079] Combination Figure 1 and Figure 2 In step S120, the second tab region 30 is folded around the folded edge 21 into the first tab region 20. The electrode sheet precursor 1100 may also be referred to as an electrode sheet before folding. In the method 1000 for manufacturing an electrode sheet, the product obtained in each step may be used as a precursor for subsequent steps.

[0080] The method 1000 for manufacturing an electrode sheet of the present application is easy to implement, avoiding large-scale modification of existing production lines and processes; there are no additional process requirements and environmental control requirements, and it can be flexibly applied to existing production lines; the quality control of the folding step is stable; the quality control of the stacking step is stable; the tab folding process and the like are easy to implement, and the product yield is high; and the aforementioned electrode sheet 110 can be manufactured.

[0081] refer to Figure 8 The present application provides a method for manufacturing a core. The method 2000 for manufacturing a core can be used to manufacture, for example, Fig. 9 The pole core 100 is shown. The pole core 100 may include a first pole piece, a separator and a second pole piece which are stacked in sequence. The first pole piece and the second pole piece have opposite polarities, one is a positive pole piece and the other is a negative pole piece. At least one of the first pole piece and the second pole piece is an electrode sheet 110, for example, both are electrode sheets 110 with folded pole tabs. The method 2000 for manufacturing the pole core is also easy to perform.

[0082] The electrode sheet precursor 1100 can be used to manufacture the electrode core 100. For example, the method 2000 for manufacturing the electrode core may include step S110 and step S120. In step S120, during folding, the substantially flat electrode ear may be folded 180° along the folded edge 21.

[0083] The electrode sheet 110 can be used to manufacture the pole core 100 . Exemplarily, the method 2000 for manufacturing the pole core includes step S220 : stacking a plurality of electrode sheets 110 , and further including arranging a separator between adjacent electrode sheets 110 .

[0084] The method 2000 for manufacturing a pole core also includes: a hot pressing process after the stacking step.

[0085] like Fig. 9 As shown, the present application provides a pole core 100, which includes at least one aforementioned electrode sheet 110. The pole core 100 has good assembly capability, good current-carrying capability, and low self-discharge rate.

[0086] In other embodiments, in combination Fig.10 , the method 2000 for manufacturing a pole core provided in the present application includes step S110, step S210 and step S120. Step S210 includes stacking a plurality of electrode sheet precursors 1100, wherein a plurality of coating areas 10 may be hot pressed. Then, the pole tabs of the plurality of electrode sheet precursors 1100 may be stacked and bonded along the Y-axis direction and folded as a whole. That is, step S120 is that a plurality of second pole tab areas 30 are folded as a whole in the first pole tab area 20 around the substantially aligned folded edges 21. The method 2000 for manufacturing a pole core of the present application is reliable to perform and can manufacture a pole core 100, and the pole core 100 includes an electrode sheet 110.

[0087] Optionally, a portion of the electrode sheet 110 in the electrode core 100 is folded as a whole.

[0088] refer to Fig.11 The present application provides a battery 200, which includes the aforementioned pole core 100. The battery 200 is safe to use, has little leakage, and has a long storage time.

[0089] The battery 200 may further include a top cover 210 and a shell 220. The pole core 100 is encapsulated in the shell 220 and the top cover 210. When manufacturing the battery 200, the pole core 100 may be connected to the top cover 210 through processes such as tab folding and welding; it may be assembled into the shell 220, and then through processes such as baking, liquid injection, and formation to obtain a finished battery 200.

[0090] Example 1

[0091] You can Figure 3The electrode sheet precursor 1100 is made into the battery 200 of Example 1, wherein the third pole ear portion 3 of the positive pole sheet and / or the negative pole sheet is first folded along the folded edge 21 of the second pole ear portion 2, so that the third pole ear portion 3 covers the area of ​​the first pole ear portion 1 and the second pole ear portion 2, and then a plurality of positive pole sheets, negative pole sheets and separators with opposite polarities are stacked in sequence to form a stacked pole core 100. Then, the battery 200 is obtained.

[0092] Example 2

[0093] You can Figure 4 The battery 200 of Example 2 made of the electrode sheet precursor 1100 shown in the figure, wherein after the lamination process is completed, the third pole ear portion 3 and the second pole ear portion 2 are folded along the folding edge 21, so that the third pole ear portion 3 covers the area of ​​the first pole ear portion 1 and the second pole ear portion 2. The multiple coating areas 10 in the formed pole core 100 are stacked, and then the battery 200 is obtained.

[0094] Example 3

[0095] Can Figure 6 The battery 200 of Example 3 made of the electrode sheet precursor 1100 shown in the figure, wherein after the lamination process is completed, the third pole ear portion 3 and the second pole ear portion 2 are folded along the folding edge 21, so that the third pole ear portion 3 covers the area of ​​the first pole ear portion 1 and the second pole ear portion 2. The multiple coating areas 10 in the formed pole core 100 are stacked, and then the battery 200 is obtained.

[0096] The battery 200 of Example 1, the battery 200 of Example 2, and the battery 200 of Example 3 may be subjected to a fast charge temperature rise test respectively.

[0097] The comparative battery can also be subjected to a fast charge temperature rise test. Fig.12 In comparative example 1, the electrode sheet 110 of the pole core 100 only includes the coating area 10 and the first pole ear area 20 of the trapezoid. The base angle of the trapezoid is 86°, the top angle θ1 is 94°, the height is 26 mm, and the width L2 of the first pole ear area 20 is 0.5 times the width L0 of the coating area 10. After the positive electrode sheet and the negative electrode sheet are laminated and hot-pressed, the pole core 100 of comparative example 1 can be obtained by the processes of ear folding and welding, and then the pole core 100 of comparative example 1 is encapsulated in a shell to obtain the battery 200 of comparative example 1.

[0098] refer to Fig.13In comparative example 2, the electrode sheet precursor 1100 includes a coating area 10, a trapezoidal first pole lug area 20, and a trapezoidal second pole lug area 30. The width L2 of the first pole lug area 20 is 0.4 times the width L0 of the coating area 10. The first pole lug area 20 and the second pole lug area 30 are equal in width at the fold 21, the height H2 of the first pole lug area 20 and the height H3 of the second pole lug area 30 are both 26 mm, the side angle θ1 of the first pole lug area 20 is 94°, and the side angle θ2 of the second pole lug area 30 is 76°. In comparative example 2, the positive electrode sheet and the negative electrode sheet can be first laminated and hot-pressed, and then the second pole lug area 30 is folded to the first pole lug area 20 along the fold 21, and the pole core 100 of comparative example 2 can be obtained by the processes of folding the pole lugs, welding, etc., and then the pole core 100 of comparative example 2 is also encapsulated in the shell to obtain the battery 200 of comparative example 2.

[0099] refer to Fig.14 In comparative example 3, the electrode sheet precursor 1100 includes a coating area 10, a first pole ear area 20, and a trapezoidal second pole ear area 30. In the first pole ear area 20, the width L1 of the first pole ear portion 1 is the same as the width of the coating area 10, the width L2 of the second pole ear portion 2 is half of the width L1 of the first pole ear portion 1, the first pole ear area 20 and the second pole ear area 30 are equal in width at the fold 21, the height H2 of the second pole ear portion 2 is 26 mm, the height H1 of the first pole ear portion 1 is 1.2 times the height H2 of the second pole ear portion 2, and the height H3 of the third pole ear portion 3 is 0.4 times the height H2 of the second pole ear portion 2. The side angle θ1 of the second pole ear portion 2 is 94°, and the side angle θ2 of the third pole ear portion 3 is 60°; the area of ​​the third pole ear portion 3 is approximately 37.53% of the area of ​​the second pole ear portion 2. In comparative example 3, the positive electrode sheets and the negative electrode sheets can be first stacked and hot pressed, and then the second pole lug area 30 can be folded onto the first pole lug area 20 along the folded edge 21. The pole core 100 of comparative example 3 can be obtained by processes such as pole lug folding and welding. Subsequently, the pole core 100 of comparative example 2 is encapsulated in a shell to obtain the battery 200 of comparative example 3.

[0100] The fast charging temperature rise test can be carried out in an environment of 25°C. The specific process can be carried out according to the steps shown in Table 1. Different steps are used when the battery state of charge (SOC) is in different ranges, and it can be charged from 0% to 100%.

[0101] Table 1 Battery fast charging process step rate (25℃)

[0102] Step magnification Battery charging status range Upper limit voltage 1) 5.0C 0-10%soc Set the upper limit voltage Vmax; 2) 5.0C 10-15%soc Set the upper limit voltage Vmax; 3) 4.6C 15-20%soc Set the upper limit voltage Vmax; 4) 4.6C 20-25%soc Set the upper limit voltage Vmax; 5) 4.6C 25-30%soc Set the upper limit voltage Vmax; 6) 4.2C 30-35%soc Set the upper limit voltage Vmax; 7) 4.2C 35-40%soc Set the upper limit voltage Vmax; 8) 4.2C 40-45%soc Set the upper limit voltage Vmax; 9) 4.2C 45-50%soc Set the upper limit voltage Vmax; 10) 4.2C 50-55%soc Set the upper limit voltage Vmax; 11) 3.6C 55-60%soc Set the upper limit voltage Vmax; 12) 3.6C 60-65%soc Set the upper limit voltage Vmax; 13) 3.2C 65-70%soc Set the upper limit voltage Vmax; 14) 3.2C 70-75%soc Set the upper limit voltage Vmax; 15) 3.2C 75-80%soc Set the upper limit voltage Vmax; 16) 2.6C 80-85%soc Set the upper limit voltage Vmax; 17) 2.6C 85-90%soc Set the upper limit voltage Vmax; 18) 1.8C 90-95%soc Set the upper limit voltage Vmax; 19) 1.0C 95-97%soc Set the upper limit voltage Vmax; 20) 0.33C 97-100%soc Set the upper limit voltage Vmax;

[0103] Before the test, a temperature sensing line was arranged in the area where the battery 200's pole lugs were gathered. During the fast charge temperature rise test, the temperature rise results of the monitoring points of the temperature sensing line were as follows: Fig.15In the comparative example 1, the maximum temperature of the tab during the fast charging process is 71.8°C; in the example 1, the maximum temperature of the tab during the fast charging process is 43.2°C; in the example 2, the maximum temperature of the tab during the fast charging process is 43.3°C; in the example 3, the maximum temperature of the tab during the fast charging process is 42.4°C.

[0104] The battery 200 of Example 3, the battery 200 of Comparative Example 2, and the battery 200 of Comparative Example 3 were subjected to a fast charge temperature rise test. Before the test, a temperature sensing line was arranged in the area where the lugs of the battery 200 were gathered. After the fast charge test, the temperature rise results of the temperature sensing line monitoring points are as follows: Fig.16 As shown: In the embodiment 3 scheme, the maximum temperature of the pole ear during the fast charging process is 42.4°C; in the comparative example 2 scheme, the maximum temperature of the pole ear during the fast charging process is 46.6°C; in the comparative example 3 scheme, the maximum temperature of the pole ear during the fast charging process is 51.2°C. It can be seen from the temperature rise test results that the larger the overlapping area of ​​the third pole ear portion 3 and the second pole ear portion 2, the larger the effective flow area connected to the top cover 210 or the metal flexible connecting sheet, the smaller the flow ohmic impedance, and the smaller the temperature rise of the pole core 100 and the battery 200.

[0105] In an exemplary embodiment, the area of ​​the third pole lug portion 3 overlapping the second pole lug portion 2 may be greater than 50%, and may be less than 95% of the area of ​​the second pole lug portion 2. The second pole lug region 30 may be completely within the second pole lug portion 2. Exemplarily, the area of ​​the second pole lug region 30 overlapping the second pole lug portion 2 is 60% to 90% of the area of ​​the second pole lug portion 2, for example, 70% or 80%.

[0106] The batteries of Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were subjected to cycle tests at 25°C using the fast charge rate shown in Table 1. Specifically, charge to the cut-off SOC and let stand for 1 hour; then discharge at a constant current rate of 1C to the cut-off voltage, and let stand for another 1 hour. The above charge and discharge process was cycled 500 times to obtain the capacity retention rate. The capacity retention rate of the battery 200 of Example 1 is 94.0%, the capacity retention rate of the battery 200 of Example 2 is 93.7%, the capacity retention rate of the battery 200 of Example 3 is 94.1%, the capacity retention rate of the battery 200 of Comparative Example 1 is 91.8%, the capacity retention rate of the battery 200 of Comparative Example 2 is 92.5%, and the capacity retention rate of the battery 200 of Comparative Example 3 is 93.2%.

[0107] After the fast charge cycle, each battery was fully charged and disassembled to observe the lithium deposition status in different areas of the fully charged negative electrode sheet, as shown in Table 2 below:

[0108] Table 2 Negative electrode lithium deposition degree

[0109] Lithium precipitation degree Example 1 0 Example 2 0 Example 3 0 Comparative Example 1 2 Comparative Example 2 1 Comparative Example 3 0

[0110] Among them, the degree of lithium precipitation at the negative electrode full charge interface is defined as follows:

[0111] 0: Lithium deposition cannot be observed with the naked eye;

[0112] 1: Trace lithium deposition, i.e., the lithium deposition area is less than 10% of the active material layer area in the preset direction;

[0113] 2: Small area lithium deposition, that is, the lithium deposition area is equivalent to 10% to 20% of the area of ​​the active material layer in the preset direction;

[0114] 3: Large-area lithium deposition, that is, the lithium deposition area is greater than 30% of the area of ​​the active material layer in the preset direction.

[0115] It can be seen from the fast charging lithium deposition test results that by adding the first pole ear portion 1, it is helpful to improve the problem of uneven current density distribution of the pole core 100 during fast charging, and can effectively solve the lithium deposition problem during fast charging.

[0116] The three batteries 200 prepared in Example 3, Comparative Example 1 and Comparative Example 3 were subjected to storage self-discharge test, and the steps were as follows: at 25°C, the pole core 100 was adjusted to 60% SOC; the battery 200 was placed in a 25±2°C environment for 24 hours, and the open circuit voltage OCV1 of the battery 200 was obtained; after being placed for another 168 hours, the open circuit voltage OCV2 of the battery 200 was obtained. The self-discharge k value (mv / h) of the battery 200 was calculated by the following formula:

[0117]

[0118] The test calculation results are shown in Table 3:

[0119] Table 3 Battery k value

[0120]

[0121] From the self-discharge test results of the battery in Example 3 and Comparative Example 1, it can be seen that by adding the first pole ear portion 1 and the third pole ear portion 3 and controlling the size within the designed range, the self-discharge performance of the battery is basically the same. From the self-discharge test results of the battery in Example 3 and Comparative Example 3, it can be seen that the k value of Comparative Example 3 increases by 78%; furthermore, when the height H1 of the first pole ear portion 1 along the Z-axis direction is designed to be small, it will be beneficial to improve the self-discharge performance of the battery.

[0122] The pole core 100 provided in the present application can be a blade battery cell structure, such as a short blade battery cell structure, in which the capacity of a single electrode is high. By designing the first pole ear area 20 and the second pole ear area 30 in the pole core 100, the flow area at the second pole ear portion 2 is increased, the heat generation of the pole ear is greatly reduced, and the problem of excessive temperature rise of the pole ear during fast charging of the blade-type battery is solved. In the battery 200, the pole core 100, and the electrode sheet 110 of the present application, the pole ear design can flexibly adjust the flow area based on parameters such as the capacity of the electrode-coated active material and the fast charging rate, and reasonably solve the problem of excessive temperature rise of the electrode sheet 110, the pole core 100 and the battery 200 during fast charging. The pole core 100 and the battery 200 have a low self-discharge rate and a long storage time.

[0123] The technical features of the embodiments disclosed above can be combined arbitrarily. To make the description concise, 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.

[0124] In the embodiments disclosed above, unless otherwise clearly specified and limited, the execution order of each step is not limited, for example, it can be executed in parallel, or it can be executed successively in different orders. The sub-steps of each step can also be executed alternately. The above-mentioned various forms of processes can be used, and steps can be reordered, added or deleted. As long as the desired results of the technical solution provided by the application can be achieved, the application is not limited here.

[0125] The embodiments disclosed above only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of patent protection of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the scope of patent protection required by the present application. Therefore, the scope of patent protection of the present application shall be subject to the attached claims.

Claims

1. An electrode sheet, characterized in that: include: coating area; A first tab region, connected to the coating region and having a folded edge away from the coating region; as well as The second pole lug region is connected to the folded edge and overlaps the first pole lug region; at any distance relative to the folded edge, the width of the second pole lug region is smaller than the width of the first pole lug region.

2. The electrode sheet according to claim 1, characterized in that: The first pole lug region includes a first pole lug portion and a second pole lug portion, and the coating region, the first pole lug portion and the second pole lug portion are connected in sequence; The width L0 of the coating area, the width L1 of the first pole ear portion, and the width L2 of the second pole ear portion satisfy the relationship: L0 ≥ L1 > L2.

3. The electrode sheet according to claim 2, characterized in that: The width of the second pole ear portion is smallest at the folded edge position.

4. The electrode sheet according to claim 3, characterized in that: The angle of the corner of the second pole lug portion at the folded edge is greater than the angle of the corresponding corner of the second pole lug region at the folded edge.

5. The electrode sheet according to claim 2, characterized in that: The second pole lug region overlaps within the second pole lug portion, or the second pole lug region partially overlaps within the first pole lug portion.

6. The electrode sheet according to claim 2, characterized in that: The height H1 of the first pole ear portion and the height H2 of the second pole ear portion satisfy: 0.05×H2≤H1≤0.5×H2; or / and An area of ​​the second pole lug region overlapping the second pole lug portion is 60% to 90% of an area of ​​the second pole lug portion.

7. A method for manufacturing an electrode sheet, characterized in that: include: forming an electrode sheet precursor, the electrode sheet precursor comprising a coating area, a first tab area connected to the coating area and having a folded edge away from the coating area, and a second tab area connected to the folded edge, wherein at any position of the same distance relative to the folded edge, the width of the second tab area is smaller than the width of the first tab area; and The second tab region is folded around the folded edge into the first tab region.

8. A method for manufacturing a pole core, characterized in that: include: The steps of the method for manufacturing an electrode sheet according to claim 7; and Before the folding step, a plurality of the electrode sheet precursors are stacked.

9. A core, characterized in that: An electrode sheet comprising the electrode sheet according to any one of claims 1 to 6 or an electrode sheet produced by the method for producing an electrode sheet according to claim 7; or The pole core is manufactured according to the method for manufacturing a pole core according to claim 8.

10. A battery, characterized in that Comprising the pole core as claimed in claim 9.

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