Cylindrical battery cells and cylindrical secondary batteries

Abstract

This application discloses a cylindrical battery cell and a cylindrical secondary battery. The cylindrical battery cell includes a first electrode sheet, a separator, and a second electrode sheet. The first electrode sheet includes a first current collector, the first current collector has a first uncoated area along the axial direction of the cylindrical battery cell, and a first chamfer is provided at an end of the first uncoated area along the winding direction of the cylindrical battery cell, and / or the second electrode sheet includes a second current collector, the second current collector has a second uncoated area along the axial direction of the cylindrical battery cell, and a second chamfer is provided at an end of the second uncoated area along the winding direction of the cylindrical battery cell. This application controls the length of the first and second distances in the first and / or second chamfers to an appropriate range, thereby avoiding a sharp corner at the end of the winding after flattening being too large, which breaks through the insulating tape and causes a short circuit with the case, which is advantageous for improving the safety performance of the battery.

Description

[Technical Field]

[0001] The present application relates to the field of battery technology, and in particular to a cylindrical battery cell and a cylindrical secondary battery. [Background Art]

[0002] To solve severe problems such as the global energy crisis, environmental pollution, climate change, and low-carbon economy, lithium batteries have developed rapidly, and their application in transportation means such as electric vehicles, electric bicycles, and power tools, as well as in the field of energy storage, has become an inevitable trend. In order to improve the output characteristics of batteries, conventional cylindrical power batteries generally adopt a full-tab flattening configuration at present. The method of flattening all tabs is to rotate the flattening ring and shrink it toward the center to press the tab foil material, so that the entire tab foil material is pressed toward the center, thereby reducing the internal resistance of the battery and improving the high-rate charge-discharge performance of the battery. However, with the increase of battery capacity, under the condition of a certain size limitation, the internal space of the battery is correspondingly reduced. During the flattening process of the battery, sharp corners are likely to be generated on the electrode sheet, which will break through the insulating tape and cause a short circuit with the casing, thereby significantly increasing safety risks. [Summary of the Invention]

[0003] The present application provides a cylindrical battery cell and a cylindrical secondary battery to solve the problem that during the flattening process of the battery, sharp corners that may break through the insulating tape are generated on the electrode sheet, which further causes a short circuit with the casing and significantly increases the safety risk.

[0004] In a first embodiment, the present invention provides a cylindrical battery cell comprising a first electrode sheet, a separator, and a second electrode sheet, wherein the cylindrical battery cell is formed by sequentially stacking and winding the first electrode sheet, the separator, and the second electrode sheet, the first electrode sheet comprising a first current collector, the first current collector having a first uncoated region along the axial direction of the cylindrical battery cell, the end of the first uncoated region along the winding direction of the cylindrical battery cell having a first chamfer, the first electrode sheet further comprising a first coating layer, the first coating layer being provided on at least one surface of the first current collector. Furthermore, the first uncoated area is provided at one end of the surface on which the first coating layer is installed on the first current collector, and / or the second electrode sheet includes a second current collector, the second current collector has a second uncoated area along the axial direction of the cylindrical battery cell, and the end of the second uncoated area along the winding direction of the cylindrical battery cell has a second chamfer, the second electrode sheet further includes a second coating layer, the second coating layer is installed on at least one surface of the second current collector, and the second uncoated area is provided at one end of the surface on which the second coating layer is installed on the second current collector. By providing the first chamfer and / or the second chamfer at the ends of the first uncoated area and / or the second uncoated area along the winding direction of the cylindrical battery cell, it is possible to avoid the formation of sharp corners on the electrode sheet that can penetrate the insulating tape during the battery planarization process, and furthermore, it is advantageous for improving the safety performance of the battery by preventing short circuits between the electrode sheet and the case.

[0005] The first chamfer and / or the second chamfer include C-chamfering and R-chamfering, that is, both C-chamfering and / or R-chamfering of the ends of the first electrode sheet and / or the second electrode sheet can prevent the electrode sheets from having sharp corners that could pierce the insulating tape during the battery planarization process.

[0006] In some embodiments, the length of the first chamfer along the first direction is a, the length of the first chamfer along the second direction is b, and the length of the first uncoated region along the second direction is c, satisfying 0.3c ≤ a ≤ 2c and 0.3c ≤ b ≤ c, where the first direction is the length direction of the first current collector and the second direction is the width direction of the first current collector.

[0007] In some embodiments, the conditions 0.6c ≤ a ≤ 1.6c and 0.5c ≤ b ≤ 0.8c are satisfied.

[0008] In some embodiments, the length of the second chamfer along the first direction is a', the length of the second chamfer along the second direction is b', and the length of the second uncoated region along the second direction is c', satisfying 0.3c' ≤ a' ≤ 2c' and 0.3c' ≤ b' ≤ c', where the first direction is the length direction of the second current collector and the second direction is the width direction of the second current collector.

[0009] In some embodiments, the conditions 0.6c′≦a′≦1.6c′ and 0.5c′≦b′≦0.8c′ are satisfied.

[0010] By controlling the length a of the first chamfer along the first direction to satisfy 0.3c ≤ a ≤ 2c, and the length b of the first chamfer along the second direction to satisfy 0.3c ≤ b ≤ c, and / or by controlling the length a' of the second chamfer along the first direction to satisfy 0.3c' ≤ a' ≤ 2c', and the length b' of the second chamfer along the second direction to satisfy 0.3c' ≤ b' ≤ c', it is possible to avoid the generation of sharp corners that can pierce the insulating tape due to the accumulation of excess uncoated foil material after planarization (where the height of the sharp corner is H ≥ 25 μm), which is advantageous for improving the safety performance of the battery. By further controlling the length a of the first chamfer along the first direction to satisfy 0.6c ≤ a ≤ 1.6c and the length b of the first chamfer along the second direction to satisfy 0.5c ≤ b ≤ 0.8c, and / or by further controlling the length a' of the second chamfer along the first direction to satisfy 0.6c' ≤ a' ≤ 1.6c' and the length b' of the second chamfer along the second direction to satisfy 0.5c' ≤ b' ≤ 0.8c', the height of the sharp corners is reduced to 15 μm or less, further improving the safety performance of the battery.

[0011] In some embodiments, insulating tape is installed around the outer periphery of the flattened surface formed after the first uncoated area and / or the second uncoated area has been flattened, and an overlapping area is installed at the joint of the surrounding insulating tape.

[0012] In some embodiments, the length of the superimposed region along the circumferential direction is 1 mm to 10 mm. By controlling the length of the superimposed region along the circumferential direction to 1 mm or more, aluminum leakage is avoided. If the length of the superimposed region along the circumferential direction is too short, there is a risk of short circuits. If the length of the superimposed region along the circumferential direction is too long, it is also undesirable, and controlling it to 10 mm or less is advantageous for improving the overall performance of the battery.

[0013] In some embodiments, the superimposed region avoids the winding end position of the electrode sheet and / or separator. If the superimposed region overlaps with the winding end position of the electrode sheet and / or separator, the diameter of the battery increases, and further affects the energy density of the battery.

[0014] In some embodiments, a finishing tape is installed around the outer circumference of the middle portion of the cylindrical battery cell, and one end of the insulating tape, closer to the finishing tape in the axial direction, does not overlap with the finishing tape. This avoids the increase in thickness due to overlapping increasing the diameter of the battery, and also prevents the battery cell from expanding due to localized pressure and compression, which can lead to problems with battery cell performance such as lithium deposition.

[0015] In some embodiments, when viewed along the height direction of the battery, the overlapping length along the axial direction between the projection of the insulating tape and the projection of the flattened surface is 2 mm to 10 mm. In this case, it is advantageous for improving the overall performance of the battery.

[0016] In some embodiments, the cylindrical battery cell includes a current collector, and the planar surface formed after the planarization of the first uncoated region and / or the second uncoated region is electrically connected to the current collector.

[0017] The current collector panel includes a positive electrode current collector panel and a negative electrode current collector panel, and the first electrode sheet may be a positive electrode sheet or a negative electrode sheet. When the first electrode sheet is a positive electrode sheet, the second electrode sheet is a negative electrode sheet, and the first flattened surface formed after the flattening of the first uncoated region of the first electrode sheet is electrically connected to the positive electrode current collector panel, and the second flattened surface formed after the flattening of the second uncoated region of the second electrode sheet is electrically connected to the negative electrode current collector panel. When the first electrode sheet is a negative electrode sheet, the second electrode sheet is a positive electrode sheet, and the first flattened surface formed after the flattening of the first uncoated region of the first electrode sheet is electrically connected to the negative electrode current collector panel, and the second flattened surface formed after the flattening of the second uncoated region of the second electrode sheet is electrically connected to the positive electrode current collector panel.

[0018] In a second aspect, the present application provides a cylindrical secondary battery including a cylindrical battery cell as described in any one of the above-described items.

[0019] The beneficial effects of the technical solutions provided by some embodiments of the present application are at least as follows: The present application provides a cylindrical battery cell comprising a first electrode sheet and a second electrode sheet, wherein the first electrode sheet has a first uncoated area, and a first chamfer is provided at the end of the first uncoated area, and the second electrode sheet has a second uncoated area, and a second chamfer is provided at the end of the second uncoated area. By controlling the lengths of the first distance and the second distance in the first chamfer and / or the second chamfer to an appropriate range, it is possible to avoid the sharp corners at the end of the winding after flattening being too large, which could pierce the insulating tape and cause a short circuit with the case, thus improving the safety performance of the battery. At the same time, the present application can improve the overall performance of the battery by controlling the position and length of the superimposed area of ​​the insulating tape, the position of the finishing tape, and the overlapping length along the axial direction of the projection of the insulating tape and the projection of the flattened surface to an appropriate range. [Brief explanation of the drawing]

[0020] In order to more clearly describe the technical solutions of the embodiments of the present application and the prior art, the drawings used in the embodiments and the prior art are briefly described below. It is obvious that the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative efforts.

[0021] [Figure 1] Figure 1 is a schematic structural diagram of a cylindrical battery cell according to an embodiment of the present application. [Figure 2] Figure 2 is a schematic structural diagram of a state of an electrode sheet according to an embodiment of the present application. [Figure 3] Figure 3 is a schematic structural diagram of a state of an electrode sheet according to another embodiment of the present application. [Figure 4] Figure 4 is a schematic diagram of an installation position of an insulating tape after planarization of a cylindrical battery cell according to an embodiment of the present application. [Figure 5] Figure 5 is a schematic diagram of an overlapping region of insulating tapes according to an embodiment of the present application. [Figure 6] Figure 6 is a diagram showing a sharp corner formed at a winding end position after planarization in Comparative Example 3 according to the present application. DETAILED DESCRIPTION OF EMBODIMENTS

[0022] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only for the purpose of illustrating the present application and are not intended to limit the present application.

[0023] Current cylindrical battery cells generally have an electrode sheet structure without chamfering, that is, the winding end position is formed by straight cutting, and a bare cell configuration in which all tabs of positive / negative tabs extend from both ends is adopted. A flattening device flattens the uncoated regions reserved at both ends of the bare cell to form flattened surfaces, which are used as welding positions. The flattened surfaces at both positive and negative ends of the bare cell are wrapped with tape. The flattened welding positions of the positive and negative electrodes after flattening are respectively laser welded to the positive and negative current collector plates of the cylindrical battery cell. Then, the bare cell is put into a case, the positive and negative current collector plates are relay welded and then respectively welded to a cover plate. Finally, end laser welding sealing or clamping sealing is performed on the cover plate and the case.

[0024] In the electrode sheet structure in the prior art, the winding end is formed by straight cutting, that is, there is no special chamfer at the winding end of the electrode sheet. In this case, during the flattening process of the battery, prominent sharp corners are easily formed on the uncoated foil material at the winding end position after flattening, which may break through the insulating tape, contact the case, and cause the risk of short circuit. In general cases, an insulating tape with a thickness of 25-30 μm is usually used. If the thickness of the insulating tape is too large, it will cause loss of energy density of the cylindrical battery cell. The height H of the sharp corner refers to the distance that the flattened region at the winding end position after flattening protrudes from the cylindrical body of the bare cell. When H≧25 μm, it is considered that the sharp corner may break through the insulating tape, contact the case, and cause a risk of short circuit.

[0025] In order to solve the above technical problems, the present application proposes a secondary battery and an electronic device.

[0026] (Cylindrical battery cell) As shown in Figure 1, the cylindrical battery cell 1 according to the present invention includes a first electrode sheet 11, a separator 12, and a second electrode sheet 13, wherein the cylindrical battery cell 1 is formed by sequentially stacking and winding the first electrode sheet 11, the separator 12, and the second electrode sheet 13, the first electrode sheet 11 includes a first current collector 101, the first current collector 101 has a first uncoated region 102 along the axial direction of the cylindrical battery cell 1, and / or, the end of the first uncoated region 102 along the winding direction of the cylindrical battery cell 1 has a first chamfer 103, and / or The second electrode sheet 13 includes a second current collector 101', the second current collector 101' has a second uncoated region 102' along the axial direction of the cylindrical battery cell 1, and a second chamfer 103' is provided at the end of the second uncoated region 102' along the winding direction of the cylindrical battery cell 1. By cutting out the first chamfer 103 and / or the second chamfer 103' at the ends of the first uncoated region 102 and / or the second uncoated region 102' along the winding direction of the cylindrical battery cell 1, that is, by cutting off the corners of a portion of the uncoated foil material, sharp corners that could pierce the insulating tape are not created after the remaining uncoated region is flattened. This avoids the generation of large sharp corners on the electrode sheet during the battery flattening process, which can pierce the insulating tape and cause a short circuit with the case, as in the prior art, and is advantageous for improving the safety performance of the battery.

[0027] In this application, the length along the first direction of the first chamfer is denoted as a, and referred to as the first distance a; the length along the second direction of the first chamfer is denoted as b, and referred to as the second distance b; the length along the second direction of the first uncoated area is denoted as c, and referred to as the width of the first uncoated area c. Here, the first direction is the length direction of the first current collector, and the second direction is the width direction of the first current collector.

[0028] In some embodiments of the present application, the first chamfer 103 is provided at the starting end of the cylindrical battery cell 1 along the winding direction in the first uncoated region 102, and / or The second chamfer 103' is provided at the starting end of the cylindrical battery cell 1 along the winding direction in the second uncoated region 102'. Here, in the first uncoated region 102 and / or the second uncoated region 102', the starting end position and the ending end position along the winding direction of the cylindrical battery cell 1 are opposite each other. For convenience in battery cell manufacturing, a chamfer is also provided at the starting end of the uncoated region in the electrode sheet along the winding direction of the cylindrical battery cell.

[0029] Let the first distance of the first chamfer 103 be a, the second distance of the first chamfer 103 be b, and the width of the first uncoated area 102 be c, satisfying 0.3c ≤ a ≤ 2c and 0.3c ≤ b ≤ c.

[0030] For example, the first distance a is a range consisting of 0.3c, 0.6c, 0.8c, 1c, 1.2c, 1.4c, 1.6c, 1.8c, 2c, or any two of the above values.

[0031] For example, the second distance b is a range consisting of 0.3c, 0.5c, 0.6c, 0.8c, 1c, or any two of the above values.

[0032] Furthermore, the conditions 0.6c ≤ a ≤ 1.6c and 0.5c ≤ b ≤ 0.8c are satisfied.

[0033] For example, the first distance a is a range consisting of 0.6c, 0.7c, 0.8c, 0.9c, 1c, 1.1c, 1.2c, 1.3c, 1.4c, 1.5c, 1.6c, or any two of the above values.

[0034] For example, the second distance b is a range consisting of 0.5c, 0.6c, 0.7c, 0.8c, or any two of the above values.

[0035] In this application, the length of the second chamfer along the first direction is denoted as a' and referred to as the first distance a', the length of the second chamfer along the second direction is denoted as b' and referred to as the second distance b', and the length of the second uncoated area along the second direction is denoted as c' and referred to as the width of the first uncoated area c'. Here, the first direction is the length direction of the second current collector, and the second direction is the width direction of the second current collector.

[0036] Let a' be the first distance of the second chamfer 103', b' be the second distance of the second chamfer 103', and c' be the width of the second uncoated area 102', satisfying 0.3c' ≤ a' ≤ 2c' and 0.3c' ≤ b' ≤ c'.

[0037] For example, the first distance a' is a range consisting of 0.3c', 0.6c', 0.8c', 1c', 1.2c', 1.4c', 1.6c', 1.8c', 2c', or any two of the above values.

[0038] For example, the second distance b is a range consisting of 0.3c', 0.5c', 0.6c', 0.8c', 1c', or any two of the above values.

[0039] Furthermore, the conditions 0.6c′≦a′≦1.6c′ and 0.5c′≦b′≦0.8c′ are satisfied.

[0040] For example, the first distance a' is a range consisting of 0.6c', 0.7c', 0.8c', 0.9c', 1c', 1.1c', 1.2c', 1.3c', 1.4c', 1.5c', 1.6c', or any two of the above values.

[0041] For example, the second distance b' is a range consisting of 0.5c', 0.6c', 0.7c', 0.8c', or any two of the above values.

[0042] The first chamfer 103 and / or the second chamfer 103' comprises at least one of C-chamfering and R-chamfering. In some embodiments of the present application, the first chamfer 103 and / or the second chamfer 103' is a C-chamfer. As shown in Figure 2, the first chamfer 103 and / or the second chamfer 103' in Figure 2 is a C-chamfer, that is, a hypotenuse is provided at the end of the first uncoated region 102 and / or the second uncoated region 102' along the winding direction of the cylindrical battery cell 1, the hypotenuse has a first end point and a second end point, the first end point is provided on a first side of the first uncoated region 102 and / or the second uncoated region 102', the second end point is provided on a second side of the first uncoated region 102 and / or the second uncoated region 102', the first side and the second side are perpendicular to each other, the first end point and the second end point respectively extend away from the first side and the second side and intersect at an intersection, the distance between the first end point and the intersection is defined as the first distance (that is, the length of a as shown in Figure 2), and the distance between the second end point and the intersection is defined as the second distance (that is, the length of b as shown in Figure 2). The length direction of the first distance refers to the extension direction of the first end point when it extends toward the intersection, and the length direction of the second distance refers to the extension direction of the second end point when it extends toward the intersection, and the length direction of the first distance is perpendicular to the length direction of the second distance.

[0043] In some other embodiments of the present application, the first chamfer 103 and / or the second chamfer 103' is an R-chamfer. As shown in Figure 3, the first chamfer 103 and / or the second chamfer 103' is an R-chamfer, that is, an arc edge is provided at the end of the first uncoated region 102 and / or the second uncoated region 102' along the winding direction of the cylindrical battery cell 1, the fillet radius of the arc edge is r, which satisfies 0.3c < r < 2c.

[0044] Illustratively, the fillet radius r of the arc edge is 0.3c, 0.5c, 0.8c, 1c, 1.3c, 1.5c, 1.7c, 2c, or a range consisting of any two of the above values.

[0045] As shown in Figures 4 and 5, an insulating tape 15 is installed around the outer circumference of the flattened surface 14 formed after the first uncoated area 102 and / or the second uncoated area 102' has been flattened, and an overlapping area 150 is installed at the joint portion of the overlapping insulating tape 15, with the length of the overlapping area 150 along the direction of rotation being 1 mm to 10 mm. As shown in Figure 5, the length of the overlapping area 150 along the direction of rotation is the width of the overlapping area 150 in the lateral direction. To avoid aluminum leakage, the length of the overlapping area along the direction of rotation is controlled to be 1 mm or more, as if the length of the overlapping area along the direction of rotation is too short, there is a risk of short circuit. Also, it is undesirable for the length of the overlapping area along the direction of rotation to be too long, and controlling it to 10 mm or less is advantageous for improving the overall performance of the battery.

[0046] For example, the length of the superimposed region 150 along the circumferential direction is in the range of 1 mm, 2 mm, 4 mm, 6 mm, 8 mm, 10 mm, or any two of the above values.

[0047] As shown in Figure 4, the superimposed region 150 avoids the winding end position of the electrode sheet and / or separator. If the superimposed region 150 overlaps with the winding end position of the electrode sheet and / or separator, the diameter of the battery increases, affecting the energy density of the battery.

[0048] As shown in Figure 1, a finishing tape 16 is installed around the outer circumference of the middle part of the cylindrical battery cell 1. One end of the insulating tape 15 that is close to the finishing tape 16 along the axial direction does not overlap with the finishing tape 16. This prevents the increase in thickness due to overlap from increasing the diameter of the battery. Furthermore, if the overlapping region 150 becomes thicker, the battery cell will be subjected to localized force and compression even after it has expanded, causing problems with the battery cell's performance, such as lithium deposition.

[0049] The overlapping length along the axial direction between the projection of the insulating tape 15 and the projection of the flattened surface 14 is 2 mm to 10 mm. By controlling the overlapping length along the axial direction between the projection of the insulating tape 15 and the projection of the flattened surface 14 to 2 mm or more, aluminum leakage is prevented from occurring in the area where the flattened surface exists. If the overlapping length along the axial direction between the projection of the insulating tape 15 and the projection of the flattened surface 14 is too short (for example, less than 2 mm), the insulating tape cannot be attached to the flattened surface, making peeling and aluminum leakage more likely. If the overlapping length along the axial direction between the projection of the insulating tape 15 and the projection of the flattened surface 14 is too long (for example, 10 mm or more), the flattened surface is too covered by the insulating tape, and the insulating tape overlaps too much with the current collector, reducing the welding area and affecting welding.

[0050] For example, the overlapping length along the axial direction between the projection of the insulating tape 15 and the projection of the flattened surface 14 is in the range of 2 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, or any two of the above values.

[0051] The cylindrical battery cell further includes a current collector (not shown), and the current collector includes at least one of a positive electrode current collector and a negative electrode current collector. The first electrode sheet 11 may be a positive electrode sheet or a negative electrode sheet. If the first electrode sheet 11 is a positive electrode sheet, the second electrode sheet 13 is a negative electrode sheet, and if the first electrode sheet 11 is a negative electrode sheet, the second electrode sheet 13 is a positive electrode sheet. That is, the first electrode sheet 11 and the second electrode sheet 13 are two types of electrode sheets with opposite polarities.

[0052] In some embodiments of the present application, the first electrode sheet 11 is used as the positive electrode sheet, the second electrode sheet 13 as the negative electrode sheet, the first flattened surface formed after the flattening of the first uncoated region 102 is electrically connected to the positive electrode current collector, and the second flattened surface formed after the flattening of the second uncoated region 102' is electrically connected to the negative electrode current collector, thereby obtaining the cylindrical battery cell 1. Subsequently, the cylindrical battery cell 1 is placed in a case, and the negative electrode current collector at one end of the cylindrical battery cell 1 is welded to the bottom of the case to make the case negatively charged, and the positive electrode current collector at the other end of the cylindrical battery cell 1 is welded to a cap to make the cap positively charged. Finally, the cover plate and the case are sealed by end laser welding or clamp sealing to form a cylindrical secondary battery.

[0053] In some other embodiments of the present application, the first electrode sheet 11 is used as the negative electrode sheet, the second electrode sheet 13 as the positive electrode sheet, the first flattened surface formed after the flattening of the first uncoated region 102 is electrically connected to the negative electrode current collector, and the second flattened surface formed after the flattening of the second uncoated region 102' is electrically connected to the positive electrode current collector, thereby obtaining the cylindrical battery cell 1. The cylindrical battery cell 1 is then placed in a case, and the negative electrode current collector at one end of the cylindrical battery cell 1 is welded to the bottom of the case to make the case negatively charged, and the positive electrode current collector at the other end of the cylindrical battery cell 1 is welded to a cap to make the cap positively charged. Finally, the cover plate and the case are sealed by end laser welding or clamp sealing to form a cylindrical secondary battery.

[0054] (Cylindrical secondary battery) The cylindrical secondary battery includes a case and a cap module, the cap module includes a cap and a cover plate, a cylindrical battery cell 1 is housed inside the case, a current collector at one end of the cylindrical battery cell 1 is welded to the bottom of the case (bottom of the case) and electrically connected, the case is negatively charged, and the current collector at the other end of the cylindrical battery cell 1 is welded to the cap and positively charged. Finally, the cover plate and the case are sealed by end laser welding or clamp sealing to form the cylindrical secondary battery. Here, the cylindrical battery cell 1 is made up of the first electrode sheet 11, the separator 12 and the second electrode sheet 13 stacked and wound in order, flattening surfaces 14 are provided at each end of the cylindrical battery cell 1, the flattening surfaces 14 include a first flattening surface and a second flattening surface, and the flattening surfaces 14 at both ends are electrically connected to the current collector. The flattened surface 14 is formed by flattening the uncoated area at one end of the first electrode sheet 11 and / or the second electrode sheet 13 along the axial direction of the cylindrical battery cell 1 using a flattening device. The first flattened surface is formed by flattening the uncoated area at one end of the first electrode sheet 11 along the axial direction of the cylindrical battery cell 1 using a flattening device, and the second flattened surface is formed by flattening the uncoated area at one end of the second electrode sheet 13 along the axial direction of the cylindrical battery cell 1 using a flattening device.

[0055] Furthermore, the first electrode sheet 11 includes a first current collector 101, the first current collector 101 has a first uncoated region 102 along the axial direction of the cylindrical battery cell 1, the end of the first uncoated region 102 along the winding direction of the cylindrical battery cell 1 has a first chamfer 103, the flattened surface formed after the flattening of the first uncoated region 102 is the first flattened surface, and / or, The second electrode sheet 13 includes a second current collector 101', the second current collector 101' has a second uncoated region 102' along the axial direction of the cylindrical battery cell 1, and a second chamfer 103' is provided at the end of the second uncoated region 102' along the winding direction of the cylindrical battery cell 1, and the flattened surface formed after the flattening of the second uncoated region 102' is the second flattened surface.

[0056] In some embodiments of the present application, the first electrode sheet 11 is a positive electrode sheet, the second electrode sheet 13 is a negative electrode sheet, the first planarized surface formed after the planarization of the first uncoated region 102 is electrically connected to the positive electrode current collector, and the second planarized surface formed after the planarization of the second uncoated region 102' is electrically connected to the negative electrode current collector.

[0057] In some other embodiments of the present application, the first electrode sheet 11 is a negative electrode sheet, the second electrode sheet 13 is a positive electrode sheet, the first planarized surface formed after the planarization of the first uncoated region 102 is electrically connected to the negative electrode current collector, and the second planarized surface formed after the planarization of the second uncoated region 102' is electrically connected to the positive electrode current collector.

[0058] In some embodiments of the present invention, an insulating tape 15 is installed around the outer periphery of the first flattened surface and / or the second flattened surface, and an overlapping region 150 is installed at the joint portion of the surrounding insulating tape 15, so that one end of the insulating tape 15 protrudes 1 mm to 5 mm from the first flattened surface and / or the second flattened surface, thereby preventing short circuits between the electrode sheet and the case.

[0059] (electronic equipment) The aforementioned electronic device includes any one of the cylindrical secondary batteries described in this application. The electronic device described in this application may be used in, but is not limited to, notebook computers, pen-input personal computers, mobile personal computers, e-book players, mobile phones, portable fax machines, portable photocopiers, portable printers, head-mounted stereo headphones, video recorders, LCD televisions, portable cleaners, portable CD players, MiniDiscs, transceivers, electronic organizers, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric assist bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household storage batteries, and lithium-ion capacitors.

[0060] The embodiments of this application will be described in more detail below with reference to examples and proportional representations.

[0061] [Example 1] (Manufacturing of cylindrical battery cells) The cylindrical battery cell 1 is formed by sequentially stacking and winding a positive electrode sheet (first electrode sheet 11), a separator 12, and a negative electrode sheet (second electrode sheet 13). The positive electrode sheet has a first uncoated area 102, the first uncoated area 102 has a first chamfer 103, the negative electrode sheet has a second uncoated area 102', and the second uncoated area 102' has a second chamfer 103'. Here, the parameters for the width of the uncoated area, and the parameters for the first chamfer 103 and the second chamfer 103' are all shown in Table 1. The width of the uncoated area in Table 1 is the width of the first uncoated area 102 and the second uncoated area 102'.

[0062] The first flattened surface formed after the flattening of the first uncoated region 102 is electrically connected to the positive electrode current collector, and the second flattened surface formed after the flattening of the second uncoated region 102' is electrically connected to the negative electrode current collector. An insulating tape 15 is installed around the outer periphery of both the first and second flattened surfaces. The lateral width of the overlapping region at the joints of the insulating tape 15 is 5 mm, and the height at which one end of the insulating tape 15 protrudes from the flattened surface is 3 mm in both cases. The thickness parameters of the insulating tape 15 are shown in Table 1. The insulating tape 15 is a commercially available general insulating tape.

[0063] (Manufacturing of cylindrical secondary batteries) The cylindrical battery cell obtained by manufacturing as described above is placed inside the case. After placing it in the case, the negative electrode current collector at one end of the cylindrical battery cell 1 is welded to the bottom of the case to create electrical conductivity, and electrolyte is injected. The positive electrode current collector at the other end of the cylindrical battery cell 1 is welded to the cap, so that the cap becomes positively charged. Finally, the cover plate and the case are sealed by end laser welding or clamp sealing to form a cylindrical secondary battery.

[0064] Furthermore, the manufacturing of the positive electrode sheet, the negative electrode sheet, the separator, and the electrolyte are all obtained by conventional methods.

[0065] [Examples 2-10] Examples 2 to 10 include most of the operating steps of Example 1, but differ from Example 1 in that some of the parameters in the manufacturing process of the cylindrical battery cell are adjusted to vary within a certain range. For details, please refer to Table 1.

[0066] [Proportional Relations 1-3] Proportional Relations 1-3 include most of the operational steps of Example 1, but differ from Example 1 in that some of the parameters in the manufacturing process of the cylindrical battery cell are adjusted to vary within a certain range. See Table 1 for details.

[0067] Testing of pointed corners: The height of the pointed corner is obtained by subtracting the radius of the cylindrical battery cell from the distance between the position of the pointed corner and the center of the circle, along a direction perpendicular to the axial direction.

[0068] Table 1

[0069] Compared with proportional examples 1 to 3, Examples 1 to 10 effectively avoid the flattened area at the winding end position after flattening exceeding 25 μm from the bare cell cylinder by controlling the first distance a / a' and second distance b / b' of the first chamfer and / or second chamfer within an appropriate range. In other words, it effectively prevents the generation of sharp corners that could pierce the insulating tape during the flattening process, further improving the safety performance of the battery. Examples 3-5 and Examples 8-9 further adjust the ranges of the first distance a / a' and the second distance b / b' of the first chamfer and / or the second chamfer to satisfy 0.6c ≤ a ≤ 1.6c and 0.5c ≤ b ≤ 0.8c and / or 0.6c' ≤ a' ≤ 1.6c' and 0.5c' ≤ b' ≤ 0.8c', thereby controlling the height of the sharp corners generated during the planarization process. In other words, the distance by which the planarized region at the winding end position after planarization extends beyond the bare cell cylinder can be controlled to 15 μm or less, further avoiding the generation of sharp corners that could pierce the insulating tape during the planarization process. In particular, when the first distance a / a' of the first chamfer and / or the second chamfer is controlled to 1.2c and the second distance b / b' of the first chamfer and / or the second chamfer is controlled to 0.6c (for example, Example 4), the height H of the sharp corner at the end of the winding after flattening is only 7 μm. When the first distance a / a' of the first chamfer and / or the second chamfer is controlled to 1.2c and the second distance b / b' of the first chamfer and / or the second chamfer is controlled to 1c (for example, Example 10), the height H of the sharp corner at the end of the winding after flattening is at most 24 μm. When the first distance a / a' of the first chamfer and / or the second chamfer in proportionality 1 and proportionality 2 is not within the appropriate range, the height H of the sharp corner at the end of the winding after flattening is as high as 30 μm, meaning that proportionality 1 and proportionality 2 can generate sharp corners that pierce the insulating tape during the process of flattening the battery.If the second distance b / b′ of the first chamfer and / or the second chamfer in proportional ratio 3 is not within an appropriate range, the height H of the sharp corner at the winding end position after flattening is high at 33 μm. In other words, proportional ratio 3 can generate sharp corners that pierce the insulating tape during the process of flattening the battery (as shown in Figure 6, the circled area in Figure 6 is the aforementioned sharp corner), thus significantly increasing the safety risk. At the same time, the embodiment according to the present invention further improves the overall performance of the battery by controlling the position and length of the insulating tape superimposed area, as well as the position of the finishing tape and the distance it extends beyond the flattened surface, within an appropriate range.

[0070] Identical or similar reference numerals in the drawings of this embodiment correspond to identical or similar parts. In this description, the orientations or positional relationships indicated by terms such as “up,” “down,” “left,” and “right” are orientations or positional relationships shown in the drawings and are for the sole purpose of simplifying the description herein. It should be understood that these do not indicate or suggest that the shown devices or components have a specific orientation, are configured in a specific orientation, or need to operate in a specific orientation. Therefore, the positional relationship terms used in the drawings are merely illustrative and should not be understood as limiting this application. A person skilled in the art will be able to understand the specific meaning of these terms depending on the context.

[0071] The above description is merely a preferred embodiment of the present application and does not limit it. Any modifications, equivalent substitutions, or improvements made within the spirit and intent of the present application should also be included within the scope of protection. [Explanation of Symbols]

[0072] 1 Cylindrical battery cell 11. First electrode sheet 101 First current collector 102 1st uncoated area 103 First chamfer 12 Separators 13. Second electrode sheet 101′ Second current collector 102′ 2nd uncoated area 103′ Second chamfer 14 Flattened surface 15. Insulating tape 150 Superimposed Regions 16 Finishing Tape

Claims

1. A cylindrical battery cell comprising a first electrode sheet, a separator, and a second electrode sheet, wherein the first electrode sheet, the separator, and the second electrode sheet are sequentially stacked and wound together, The first electrode sheet includes a first current collector, the first current collector has a first uncoated region along the axial direction of the cylindrical battery cell, the end of the first uncoated region along the winding direction of the cylindrical battery cell has a first chamfer, the length of the first chamfer along the longitudinal direction of the first current collector is a, the length of the first chamfer along the width direction of the first current collector is b, the length of the first uncoated region along the width direction of the first current collector is c, and 0.3c ≤ a ≤ 2c and 0.3c ≤ b ≤ 0.6c, and / or The second electrode sheet includes a second current collector, the second current collector has a second uncoated region along the axial direction of the cylindrical battery cell, the end of the second uncoated region along the winding direction of the cylindrical battery cell has a second chamfer, the length of the second chamfer along the longitudinal direction of the second current collector is a', the length of the second chamfer along the width direction of the second current collector is b', and the length of the second uncoated region along the width direction of the second current collector is c', satisfying 0.3c' ≤ a' ≤ 2c' and 0.3c' ≤ b' ≤ 0.6c'. An insulating tape is installed around the outer periphery of the flattened surface formed after the first uncoated region and / or the second uncoated region has been flattened, and an overlapping region is installed at the joint of the surrounding insulating tape. Cylindrical battery cell.

2. Satisfying 0.6c ≤ a ≤ 1.6c and 0.5c ≤ b ≤ 0.6c, A cylindrical battery cell according to claim 1.

3. Satisfying 0.6c' ≤ a' ≤ 1.6c' and 0.5c' ≤ b' ≤ 0.6c', A cylindrical battery cell according to claim 1.

4. The length of the superimposed region along the direction of the circumferential movement of the insulating tape is 1 mm to 10 mm. A cylindrical battery cell according to claim 1.

5. The superimposed region avoids the winding end position of the electrode sheet and / or separator. A cylindrical battery cell according to claim 1.

6. A finishing tape is installed around the outer circumference of the middle portion of the cylindrical battery cell, and one end of the insulating tape that is close to the finishing tape in the axial direction does not overlap with the finishing tape. A cylindrical battery cell according to claim 1.

7. When viewed along the height direction of the battery, the overlapping length along the axial direction between the projection of the insulating tape and the projection of the flattened surface is 2 mm to 10 mm. The cylindrical battery cell according to claim 6.

8. The cylindrical battery cell includes a current collector, The flattened surface formed after the flattening of the first uncoated region and / or the second uncoated region is electrically connected to the current collector panel. A cylindrical battery cell according to claim 1.

9. A cylindrical secondary battery comprising a cylindrical battery cell according to any one of claims 1 to 8.

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