Cylindrical battery cell and cylindrical secondary battery

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 cylindrical battery cells and cylindrical secondary batteries. [Background technology]

[0002] In order to solve the severe problems such as global energy crisis, environmental pollution, climate change, and low-carbon economy, the development of lithium batteries is rapid, and their application in the fields of transportation and energy storage, especially in electric vehicles, electric bicycles, and power tools, is an inevitable trend. In order to improve the output characteristics of the battery, at present, traditional cylindrical power batteries generally adopt a full-tab flattening configuration. The full-tab flattening method is to rotate the flattening wheel and shrink it toward the center to compress the tab foil material, so that the entire tab foil material is crushed toward the center, reducing the internal resistance of the battery and improving the high-rate charge and discharge performance of the battery. However, with the improvement of battery capacity, under the limited conditions of a certain size, the space inside the battery is reduced accordingly, and in the process of flattening the battery, sharp corners are easily generated on the electrode sheet, which breaks through the insulating tape and causes a short circuit with the case, which significantly increases the safety risk. 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 a battery, sharp corners are generated on the electrode sheet that may break through the insulating tape, and further cause a short circuit with the case, significantly increasing the safety risk.

[0004] As a first aspect, an embodiment of the present application provides a cylindrical battery cell, the cylindrical battery cell including a first electrode sheet, a separator, and a second electrode sheet, the cylindrical battery cell being formed by sequentially stacking and rolling the first electrode sheet, the separator, and the second electrode sheet, the first electrode sheet including a first current collector, the first current collector having a first uncoated area along an axial direction of the cylindrical battery cell, a first chamfer being formed at an end of the first uncoated area along a rolling direction of the cylindrical battery cell, the first electrode sheet further including a first coating layer, the first coating layer being formed on at least one surface of the first current collector. and the first uncoated area is provided at one end of the surface of the first current collector on which the first coating layer is provided, and / or the second electrode sheet includes a second current collector, the second current collector is provided with 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, the second electrode sheet further includes a second coating layer, the second coating layer is provided on at least one surface of the second current collector, and the second uncoated area is provided at one end of the surface of the second current collector on which the second coating layer is provided. By providing the first chamfer and / or the second chamfer at the end of the first uncoated area and / or the second uncoated area along the winding direction of the cylindrical battery cell, it is possible to prevent the electrode sheet from having sharp corners that may break through the insulating tape during the flattening process of the battery, and further to prevent the occurrence of a short circuit between the electrode sheet and the case, which is advantageous for improving the safety performance of the battery.

[0005] The first chamfer and / or the second chamfer include C-chamfer and R-chamfer, i.e., the C-chamfer processing and / or R-chamfer processing on the ends of the first electrode sheet and / or the second electrode sheet can prevent the electrode sheets from having sharp corners that may break through the insulating tape during the battery flattening process.

[0006] In some embodiments, a is the length of the first chamfer along a first direction, b is the length of the first chamfer along a second direction, and c is the length of the first uncoated area along the second direction, 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, 0.6c≦a≦1.6c and 0.5c≦b≦0.8c are satisfied.

[0008] In some embodiments, a' is the length of the second chamfer along the first direction, b' is the length of the second chamfer along the second direction, and c' is the length of the second uncoated area along the second direction, 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, 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 may break through the insulating tape due to the accumulation of uncoated foil material remaining after flattening (here, the height of the sharp corners 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 kept to 15 μm or less, further improving the safety performance of the battery.

[0011] In some embodiments, an insulating tape is placed around the outer periphery of the planarized surface formed after planarization of the first uncoated area and / or the second uncoated area, and an overlap area is provided at the joint of the surrounding insulating tape.

[0012] In some embodiments, the length of the overlapping region along the circumferential direction is 1 mm to 10 mm. By controlling the length of the overlapping region along the circumferential direction to 1 mm or more, aluminum leakage can be avoided, while if the length of the overlapping region along the circumferential direction is too short, there is a risk of short circuiting, and it is also not preferable that the length of the overlapping region along the circumferential direction is too long. Controlling the length to 10 mm or less is advantageous for improving the performance of the entire battery.

[0013] In some embodiments, the overlapping area avoids the end of the winding of the electrode sheet and / or the separator. If the overlapping area overlaps the end of the winding of the electrode sheet and / or the separator, the diameter of the battery will increase, which will further affect the energy density of the battery.

[0014] In some embodiments, a finishing tape is installed around the outer circumference of the cylindrical battery cell middle part, and one end of the insulating tape close to the finishing tape along the axial direction does not overlap with the finishing tape, thereby avoiding an increase in thickness due to overlapping, which would increase the diameter of the battery, and if the overlapped area becomes thick, the battery cell will expand and be locally compressed, causing problems in battery cell performance such as lithium precipitation.

[0015] In some embodiments, when viewed along the height direction of the battery, the overlap 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, which is advantageous for improving the performance of the entire battery.

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

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

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

[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, which includes a first electrode sheet and a second electrode sheet, the first electrode sheet being provided with a first uncoated area, a first chamfer being provided at an end of the first uncoated area, and the second electrode sheet being provided with a second uncoated area, and a second chamfer being provided at an end of the second uncoated area. By controlling the length of the first distance and the length of the second distance in the first chamfer and / or the second chamfer within an appropriate range, it is possible to avoid the 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 favorable for improving the safety performance of the battery. At the same time, the present application can improve the performance of the entire battery by controlling the position and length of the overlapping 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 within an appropriate range. [Brief description of the drawings]

[0020] In order to more clearly explain 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 merely some embodiments of the present application, and other drawings can be obtained based on these drawings without creative efforts by those skilled in the art.

[0021] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a cylindrical battery cell according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of an electrode sheet in one embodiment of the present application. [Diagram 3] FIG. 3 is a schematic diagram showing the configuration of an electrode sheet in another embodiment according to the present application. [Figure 4] FIG. 4 is a schematic diagram of the placement position of an insulating tape after flattening a cylindrical battery cell in an embodiment of the present application. [Diagram 5] FIG. 5 is a schematic diagram of an overlapping region of an insulating tape in an embodiment according to the present application. [Figure 6] FIG. 6 is a diagram showing a sharp corner generated at the end of the winding after flattening in Comparative Example 3 according to the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be described in more detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only for 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, a bare cell configuration in which the end of winding is formed by a straight cut and all positive / negative tabs protrude from both ends. A flattening device is used to flatten the reserved uncoated areas on both ends of the bare cell to form flattened surfaces, which are used as welding positions. The flattened surfaces on both ends of the positive and negative electrodes of the bare cell are wrapped with tape, and the welding positions of the positive and negative electrodes after flattening are laser welded to the positive and negative current collectors of the cylindrical battery cell. The bare cell is then inserted into a case, and the positive and negative current collectors are relay welded, and then welded to cover plates, respectively. Finally, the cover plates and the case are end laser welded or clamp sealed.

[0024] In the electrode sheet structure of the prior art, the end of the winding is formed by straight cutting, that is, there is no special chamfering at the end of the winding of the electrode sheet. In this case, in the flattening process of the battery, a sharp corner is easily generated in the uncoated foil material at the end of the winding after flattening, which breaks through the insulating tape and contacts the case, resulting in a risk of short circuit. In general, an insulating tape with a thickness of 25-30 μm is used, and if the insulating tape is too thick, it will cause a loss of energy density of the cylindrical battery cell. The height H of the sharp corner is the distance that the flattened area at the end of the winding after flattening protrudes from the cylindrical body of the bare cell. If H≧25 μm, it is considered that there is a risk that the sharp corner will break through the insulating tape and contact the case, resulting in a 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 FIG. 1 , a cylindrical battery cell 1 according to the present application includes a first electrode sheet 11, a separator 12, and a second electrode sheet 13, and the cylindrical battery cell 1 is formed by sequentially stacking and rolling the first electrode sheet 11, the separator 12, and the second electrode sheet 13, and the first electrode sheet 11 includes a first current collector 101, and a first uncoated area 102 is provided on the first current collector 101 along the axial direction of the cylindrical battery cell 1, and a first chamfer 103 is provided at an end of the first uncoated area 102 along the rolling direction of the cylindrical battery cell 1, and / or The second electrode sheet 13 includes a second current collector 101', and a second uncoated area 102' is provided on the second current collector 101' along the axial direction of the cylindrical battery cell 1, and a second chamfer 103' is provided at an end of the second uncoated area 102' in the winding direction of the cylindrical battery cell 1. By cutting out the first chamfer 103 and / or the second chamfer 103' at the end of the first uncoated area 102 and / or the second uncoated area 102' in the winding direction of the cylindrical battery cell 1, i.e., by cutting off corners of a portion of the uncoated foil material, sharp corners that may break through the insulating tape are not generated after the remaining uncoated area is flattened, and it is possible to avoid a large sharp corner being generated on the electrode sheet during the flattening process of the battery, which breaks through the insulating tape and causes a short circuit with the case as in the conventional technology, which is advantageous to improving the safety performance of the battery.

[0027] In the present application, the length of the first chamfer in the first direction is denoted as a and is referred to as the first distance a, the length of the first chamfer in the second direction is denoted as b and is referred to as the second distance b, the length of the first uncoated region in the second direction is denoted as c and is referred to as the first uncoated region width 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 beginning end of the first uncoated area 102 along the winding direction of the cylindrical battery cell 1; and / or The second chamfer 103′ is provided at a start end of the second uncoated region 102′ along the winding direction of the cylindrical battery cell 1, Here, in the first uncoated region 102 and / or the second uncoated region 102', the starting end position in the winding direction of the cylindrical battery cell 1 faces the end position. For convenience in manufacturing the battery cell, a chamfer is also provided at the starting end of the uncoated region of the electrode sheet in the winding direction around the cylindrical battery cell.

[0029] A first distance of the first chamfer 103 is a, a second distance of the first chamfer 103 is b, and a width of the first uncoated region 102 is c, satisfying 0.3c≦a≦2c and 0.3c≦b≦c.

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

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

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

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

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

[0035] In this application, the length of the second chamfer along the first direction is designated as a' and is referred to as the first distance a', the length of the second chamfer along the second direction is designated as b' and is referred to as the second distance b', the length of the second uncoated area along the second direction is designated as c' and is 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] A first distance of the second chamfer 103' is a', a second distance of the second chamfer 103' is b', and a width of the second uncoated area 102' is c', satisfying 0.3c'≦a'≦2c' and 0.3c'≦b'≦c'.

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

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

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

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

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

[0042] The first chamfer 103 and / or the second chamfer 103' include at least one of a C-chamfer and an R-chamfer. In some embodiments of the present application, the first chamfer 103 and / or the second chamfer 103' are C-chamfers. As shown in FIG. 2, the first chamfer 103 and / or the second chamfer 103' in FIG. 2 are C-chamfers, that is, bevels are provided at the ends along the winding direction of the cylindrical battery cell 1 in the first non-coated region 102 and / or the second non-coated region 102'. The bevel has a first end point and a second end point. The first end point is provided on the first side of the first non-coated region 102 and / or the second non-coated region 102', and the second end point is provided on the second side of the first non-coated region 102 and / or the second non-coated region 102'. The first side and the second side are perpendicular. The first end point and the second end point extend away from the first side and the second side respectively and intersect at an intersection point. The distance between the first end point and the intersection point is defined as the first distance (that is, as shown in FIG. 2, the length of a), and the distance between the second end point and the intersection point is defined as the second distance (that is, as shown in FIG. 2, the length of b). The length direction of the first distance is the extension direction when the first end point extends towards the intersection point, and the length direction of the second distance is the extension direction when the second end point extends towards the intersection point. 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' are R-chamfers. As shown in FIG. 3, the first chamfer 103 and / or the second chamfer 103' are R-chamfers, that is, arc edges are provided at the ends along the winding direction of the cylindrical battery cell 1 in the first non-coated region 102 and / or the second non-coated region 102'. Taking the fillet radius of the arc edge as r, it satisfies 0.3c < r < 2c.

[0044] Exemplarily, 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 FIG. 4 and FIG. 5, an insulating tape 15 is provided around the outer periphery of the flattened surface 14 formed after flattening the first non-coated region 102 and / or the second non-coated region 102′, and an overlapping region 150 is provided at the joint of the surrounding insulating tape 15, and the length of the overlapping region 150 along the circumferential direction is 1 mm to 10 mm. As shown in FIG. 5, the length of the overlapping region 150 along the circumferential direction is the width in the lateral direction of the overlapping region 150. In order to avoid aluminum leakage, the length of the overlapping region along the circumferential direction is controlled to 1 mm or more, and if the length of the overlapping region along the circumferential direction is too short, there is a risk of short circuit. In addition, it is not preferable that the length of the overlapping region along the circumferential direction is too long, and it is advantageous to control it to 10 mm or less in order to improve the performance of the entire battery.

[0046] Exemplarily, the length of the overlapping region 150 along the circumferential direction is 1 mm, 2 mm, 4 mm, 6 mm, 8 mm, 10 mm, or a range consisting of any two of the above values.

[0047] 4, the overlapping region 150 avoids the winding end position of the electrode sheet and / or the separator. If the overlapping region 150 overlaps with the winding end position of the electrode sheet and / or the separator, the diameter of the battery will increase, which will affect the energy density of the battery.

[0048] As shown in FIG. 1 , a finishing tape 16 is installed around the outer periphery of the middle part of the cylindrical battery cell 1, and one end of the insulating tape 15 close to the finishing tape 16 along the axial direction does not overlap with the finishing tape 16, thereby preventing an increase in thickness due to the overlap from increasing the diameter of the battery. Furthermore, if the overlap region 150 becomes thicker, it will be locally compressed and subjected to force even after the battery cell expands, causing problems in battery cell performance such as lithium precipitation.

[0049] The overlap length of the projection of the insulating tape 15 and the projection of the flattened surface 14 along the axial direction is 2 mm to 10 mm. By controlling the overlap length of the projection of the insulating tape 15 and the projection of the flattened surface 14 along the axial direction to 2 mm or more, the area where the flattened surface exists is protected from aluminum leakage. If the overlap length of the projection of the insulating tape 15 and the projection of the flattened surface 14 along the axial direction is too short (for example, less than 2 mm), the insulating tape cannot be attached to the flattened surface, and peeling and aluminum leakage are likely to occur. If the overlap length of the projection of the insulating tape 15 and the projection of the flattened surface 14 along the axial direction is too long (for example, 10 mm or more), the flattened surface is covered too much by the insulating tape and the insulating tape overlaps too much with the current collector, so the welding area is reduced and welding is affected.

[0050] Illustratively, the overlap length along the axial direction between the projection of the insulating tape 15 and the projection of the flattening surface 14 is 2 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, or a range consisting of 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 current collector and a negative current collector. The first electrode sheet 11 may be a positive electrode sheet or a negative electrode sheet, and when the first electrode sheet 11 is a positive electrode sheet, the second electrode sheet 13 is a negative electrode sheet, and when 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 a positive electrode sheet, the second electrode sheet 13 is a negative electrode sheet, the first flattened surface formed after flattening the first uncoated region 102 is electrically connected to the positive current collector, and the second flattened surface formed after flattening the second uncoated region 102' is electrically connected to the negative current collector, thereby obtaining the cylindrical battery cell 1. Then, the cylindrical battery cell 1 is placed in a case, and the negative current collector at one end of the cylindrical battery cell 1 is welded and conductive to the bottom of the case, so that the case is negatively charged, and the positive current collector at the other end of the cylindrical battery cell 1 is welded to a cap, so that the cap is positively charged. Finally, the cover plate and the case are end-laser welded and sealed or clamped to form a cylindrical secondary battery.

[0053] 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 flattened surface formed after flattening the first uncoated area 102 is electrically connected to the negative current collector, and the second flattened surface formed after flattening the second uncoated area 102' is electrically connected to the positive current collector, thereby obtaining the cylindrical battery cell 1. Then, the cylindrical battery cell 1 is placed in a case, and the negative current collector at one end of the cylindrical battery cell 1 is welded and conductive to the bottom of the case, so that the case is negatively charged, and the positive current collector at the other end of the cylindrical battery cell 1 is welded to a cap, so that the cap is positively charged. Finally, the cover plate and the case are end-laser welded and sealed or clamped 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 accommodated 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 the case is negatively charged, and a current collector at the other end of the cylindrical battery cell 1 is welded to the cap and the cap is positively charged. Finally, the cover plate and the case are end-laser welded and sealed or clamped to form a cylindrical secondary battery. Here, the cylindrical battery cell 1 is formed by stacking and rolling the first electrode sheet 11, the separator 12, and the second electrode sheet 13 in this order, and a flattened surface 14 is provided at each end of the cylindrical battery cell 1, the flattened surface 14 includes a first flattened surface and a second flattened surface, and the flattened surfaces 14 at both ends are electrically connected to the current collectors. The planarized surface 14 is formed by planarizing an 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 planarizing device. The uncoated area at one end of the first electrode sheet 11 along the axial direction of the cylindrical battery cell 1 is planarized by a planarizing device to form a first planarized surface, and the uncoated area at one end of the second electrode sheet 13 along the axial direction of the cylindrical battery cell 1 is planarized by a planarizing device to form a second planarized surface.

[0055] Further, the first electrode sheet 11 includes a first current collector 101, a first uncoated area 102 is provided on the first current collector 101 along the axial direction of the cylindrical battery cell 1, a first chamfer 103 is provided at an end of the first uncoated area 102 along the winding direction of the cylindrical battery cell 1, and a flattened surface formed after flattening the first uncoated area 102 is the first flattened surface; and / or The second electrode sheet 13 includes a second current collector 101', a second uncoated area 102' is provided on the second current collector 101' along the axial direction of the cylindrical battery cell 1, a second chamfer 103' is provided at an end of the second uncoated area 102' along the winding direction of the cylindrical battery cell 1, and the flattened surface formed after flattening the second uncoated area 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, a first planarized surface formed after planarization of the first uncoated area 102 is electrically connected to the positive current collector, and a second planarized surface formed after planarization of the second uncoated area 102' is electrically connected to the negative 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, a first planarized surface formed after planarization of the first uncoated area 102 is electrically connected to the negative electrode current collector, and a second planarized surface formed after planarization of the second uncoated area 102' is electrically connected to the positive electrode current collector.

[0058] In some embodiments of the present application, an insulating tape 15 is placed around the outer periphery of the first planarized surface and / or the second planarized surface, and an overlap region 150 is provided at the joint of the surrounding insulating tape 15, and one end of the insulating tape 15 protrudes 1 mm to 5 mm from the first planarized surface and / or the second planarized surface, thereby avoiding the occurrence of a short circuit between the electrode sheet and the case.

[0059] (electronic equipment) The electronic device includes any one of the cylindrical secondary batteries of the present application, which may be used in, but is not limited to, notebook computers, pen-input computers, mobile computers, e-book players, mobile phones, mobile fax machines, mobile copiers, mobile printers, head-mounted stereo headphones, video recorders, LCD televisions, mobile cleaners, mobile CD players, mini-disks, transceivers, electronic organizers, calculators, memory cards, mobile recorders, radios, backup power sources, motors, automobiles, motorcycles, power-assisted bicycles, bicycles, lighting equipment, toys, game consoles, watches, power tools, flashlights, cameras, large-scale household storage batteries, and lithium ion capacitors.

[0060] Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

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

[0062] a first planarized surface formed after planarizing the first uncoated region 102 is electrically connected to the positive electrode current collector, and a second planarized surface formed after planarizing 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 planarized surface and the second planarized surface, the lateral width of the overlapping area at the joint of the surrounding insulating tape 15 is 5 mm, the height at which one end of the insulating tape 15 protrudes from the planarized surface is 3 mm, and the thickness parameters of the insulating tape 15 are shown in Table 1. The insulating tape 15 is a common insulating tape available on the market.

[0063] (Manufacturing cylindrical secondary batteries) The cylindrical battery cell manufactured as described above is placed inside a case. After the cylindrical battery cell is inserted into the case, the negative current collector at one end of the cylindrical battery cell 1 is welded to the bottom of the case for electrical connection, an electrolyte is injected, the positive current collector at the other end of the cylindrical battery cell 1 is welded to a cap, and the cap is positively charged. Finally, the cover plate and the case are end-laser welded or clamped to form a cylindrical secondary battery.

[0064] The positive electrode sheet, the negative electrode sheet, the separator, and the electrolyte are all produced by conventional methods.

[0065] [Examples 2 to 10] Examples 2 to 10 include most of the operation 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 change within a certain range. Specifically, see Table 1.

[0066] [Comparison 1~3] Comparative Examples 1 to 3 include most of the operation 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 change within a certain range.

[0067] Sharp corner test: The height of the sharp corner is determined by subtracting the radius of the cylindrical battery cell from the distance between the sharp corner and the center of the circle along the direction perpendicular to the axial direction.

[0068]

Table 1

[0069] In comparison with Comparative Examples 1 to 3, Examples 1 to 10 controlled the first distance a / a' and the second distance b / b' of the first chamfer and / or the second chamfer within an appropriate range, thereby effectively preventing the flattened region at the end of the winding after flattening from protruding from the cylindrical body of the bare cell by more than 25 μm. In other words, it effectively prevented the occurrence of sharp corners that could break through the insulating tape during the flattening process, and further improved the safety performance of the battery. In Examples 3 to 5 and Examples 8 to 9, by adjusting the range 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', the height of the sharp corners that occur during the flattening process can be controlled; in other words, the distance by which the flattened region at the end of the winding after flattening protrudes from the bare cell cylinder can be controlled to 15 μm or less, thereby further avoiding the occurrence of sharp corners that may puncture the insulating tape during the flattening 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 (e.g., Example 4), the height H of the sharp corner at the end of the winding after flattening is only 7 μm, and 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 (e.g., Example 10), the height H of the sharp corner at the end of the winding after flattening is only 24 μm at maximum. When the first distance a / a' of the first chamfer and / or the second chamfer in Comparative Examples 1 and 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, that is, in Comparative Examples 1 and 2, a sharp corner that breaks through the insulating tape may occur during the flattening of the battery.In Comparative Example 3, when the second distance b / b' of the first chamfer and / or the second chamfer is not within an appropriate range, the height H of the sharp corner at the end of the winding after flattening is as high as 33 μm, that is, in Comparative Example 3, a sharp corner that breaks through the insulating tape may occur during the flattening process of the battery (as shown in FIG. 6, the circled part in FIG. 6 is the above-mentioned sharp corner), thus significantly increasing the safety risk. At the same time, the embodiment of the present application further improves the performance of the entire battery by controlling the position and length of the overlapping area of ​​the insulating tape, as well as the position of the finishing tape and the distance that it protrudes from the flattening surface within an appropriate range.

[0070] The same or similar reference numerals in the drawings of this embodiment correspond to the same or similar parts. In the description of this application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right" and the like is the orientation or positional relationship indicated based on the drawings, and is intended only to simplify the description of this specification, and is not intended to indicate or suggest that the devices or components shown have a specific orientation, are configured in a specific orientation, and must operate in a specific orientation. Therefore, the terms of positional relationship described in the drawings are merely illustrative descriptions, and cannot be understood to limit the present application, and those skilled in the art can understand the specific meaning of the above terms according to the circumstances.

[0071] The above description is only a preferred embodiment of the present application, and does not limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and scope of the present application should be included in the protection scope of the present application. [Explanation of symbols]

[0072] 1 Cylindrical battery cell 11 First electrode sheet 101 First current collector 102 1st uncoated area 103 First chamfer 12 Separator 13 Second electrode sheet 101' Second current collector 102′ 2nd uncoated area 103' 2nd chamfer 14 Flattened surface 15 Electrical tape 150 overlapping areas 16 Finishing Tape

Claims

1. A cylindrical battery cell including a first electrode sheet, a separator, and a second electrode sheet, the first electrode sheet, the separator, and the second electrode sheet being stacked in order and wound, the first electrode sheet includes a first current collector, the first current collector has a first uncoated area along an axial direction of the cylindrical battery cell, and a first chamfer is provided at an end of the first uncoated area along a winding direction of the cylindrical battery cell; and / or the second electrode sheet includes a second current collector, a second uncoated area is provided on the second current collector along an axial direction of the cylindrical battery cell, and a second chamfer is provided on an end of the second uncoated area along a winding direction of the cylindrical battery cell. Cylindrical battery cell.

2. a length of the first chamfer along a first direction is defined as a, a length of the first chamfer along a second direction is defined as b, and a length of the first uncoated region along the second direction is defined as c, satisfying 0.3c≦a≦2c and 0.3c≦b≦c; the first direction is a length direction of the first current collector, The second direction is a width direction of the first current collector.

2. The cylindrical battery cell of claim 1.

3. a' is a length of the second chamfer along the first direction, b' is a length of the second chamfer along the second direction, and c' is a length of the second uncoated region along the second direction, satisfying 0.3c'≦a'≦2c' and 0.3c'≦b'≦c'; the first direction is a length direction of the second current collector, The second direction is a width direction of the second current collector.

2. The cylindrical battery cell of claim 1.

4. 0.6c≦a≦1.6c and 0.5c≦b≦0.8c are satisfied; 3. The cylindrical battery cell of claim 2.

5. 0.6c'≦a'≦1.6c' and 0.5c'≦b'≦0.8c' are satisfied, 4. The cylindrical battery cell of claim 3.

6. an insulating tape is provided around an outer periphery of a flattened surface formed after flattening the first uncoated region and / or the second uncoated region, and an overlapping region is provided at a joint of the surrounding insulating tape; 2. The cylindrical battery cell of claim 1.

7. The length of the overlapping region along the circumferential direction is 1 mm to 10 mm.

7. The cylindrical battery cell of claim 6.

8. The overlapping region avoids the end of the winding of the electrode sheet and / or the separator.

7. The cylindrical battery cell of claim 6.

9. a finishing tape is installed around the outer periphery of the middle part 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; 7. The cylindrical battery cell of claim 6.

10. When viewed along the height direction of the battery, the overlap 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; 10. The cylindrical battery cell of claim 9.

11. The cylindrical battery cell includes a current collector, A flattened surface formed after flattening the first uncoated area and / or the second uncoated area is electrically connected to the collector plate.

7. The cylindrical battery cell of claim 6.

12. A cylindrical secondary battery comprising the cylindrical battery cell according to any one of claims 1 to 11.

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