Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a secondary battery, a battery pack and an electronic device. The secondary battery includes: a case; the electrode assembly is contained in the shell, a winding structure of the electrode assembly comprises a main body part and a tab protruding out of one end of the main body part in the height direction of the winding structure, the tab is a cut and stacked tab, the tab is bent towards a center hole of the winding structure, and the tab comprises a first surface facing the center hole and a second surface deviating from the center hole; the tab comprises a flat part and a vertical part connected between the main body part and the flat part, the flat part is arranged along the radial direction of the winding structure, and the vertical part is arranged along the height direction; wherein the tabs comprise outer ring tabs located on the outermost ring, and the second surfaces of the flat parts of at least part of the outer ring tabs are provided with sunken structures which are sunken towards the direction close to the main body part in the height direction. By arranging the sunken structure, the welding contact area can be enlarged, so that the problems of insufficient welding or unstable welding structure and the like are avoided, and the yield of the battery cell is greatly improved.

Description

Technical Field

[0001] This utility model relates to the field of secondary batteries, and in particular to a secondary battery, a battery pack, and an electronic device. Background Technology

[0002] In recent years, with the rapid development of electric vehicles, consumer electronics, and new energy storage systems, battery technology has become an important factor in the development of electric vehicles.

[0003] In the development of battery technology, how to improve the yield rate of battery cells is a technical problem that urgently needs to be solved. Utility Model Content

[0004] The technical problem to be solved by this utility model is to overcome the above-mentioned technical problems of the prior art and provide a secondary battery, a battery pack and an electronic device.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution:

[0006] A secondary battery, characterized in that it comprises:

[0007] case;

[0008] An electrode assembly is housed within the housing. The electrode assembly includes a winding structure, which includes a main body and an electrode tab protruding from one end of the main body along the height direction of the winding structure. The electrode tab is a folded electrode tab, which is bent toward the central hole of the winding structure. The electrode tab includes a first surface facing the central hole and a second surface away from the central hole. The electrode tab includes a flat portion and a vertical portion connecting the main body and the flat portion. The flat portion is arranged radially along the winding structure, and the vertical portion is arranged along the height direction.

[0009] The electrode includes an outer ring electrode located at the outermost ring, and at least a portion of the second surface of the flat portion of the outer ring electrode has a recessed structure, which is recessed towards the main body along the height direction.

[0010] In this technical solution, by providing a recessed structure on the second surface of the flat portion of at least a portion of the outer ring tabs, the welding contact area can be expanded, thereby avoiding problems such as poor welding or unstable welding structure, and greatly improving the yield of the battery cell; and, it can effectively reduce the welding internal resistance, thereby achieving the beneficial effect of reducing the battery internal resistance.

[0011] Preferably, the electrode tab further includes multiple inner electrode tabs located within the outer electrode tab, and at least a portion of the second surface of the flat portion of the inner electrode tab is provided with the recessed structure, and along the height direction, at least a portion of the recessed structures located on the multiple inner electrode tabs are not blocked by other stacked electrode tabs.

[0012] Preferably, the direction from the main body to the tab is predetermined, the recessed structure is disposed near the outer edge of the tab away from the main body along the predetermined direction, and has a non-zero distance between the recessed structure and the outer edge of the tab away from the main body along the predetermined direction; and / or,

[0013] Along the winding direction of the winding structure, the recessed structure is located in the central region of the second surface; and / or,

[0014] One or more of the recessed structures are provided on the second surface of the same electrode tab; and / or,

[0015] The recessed structures on the second surface of the various electrodes are positioned in the same location; and / or,

[0016] The maximum circumcircle of the recessed structure is less than or equal to 1 mm; and / or,

[0017] The recessed structure is circular in shape; and / or,

[0018] The depth of the recessed structure is 30%-100% of the thickness of the tab.

[0019] Preferably, at least a portion of the first surface of the flat portion of the outer ring tabs is provided with a raised structure, the raised structure protruding towards the main body portion along the height direction.

[0020] Preferably, the electrode tab also includes multiple inner electrode tabs located within the outer electrode tab, and at least a portion of the first surface of the flat portion of the inner electrode tab is provided with the protrusion structure.

[0021] Preferably, the direction from the main body to the tab is predetermined, the protruding structure is disposed near the outer edge of the tab away from the main body along the predetermined direction, and has a non-zero distance between it and the outer edge of the tab away from the main body along the predetermined direction; and / or,

[0022] Along the winding direction of the winding structure, the protrusion structure is located in the central region of the first surface; and / or,

[0023] One or more of the protruding structures are provided on the first surface of the same electrode tab; and / or,

[0024] The protrusions on the first surfaces of the various electrodes are positioned identically; and / or,

[0025] The maximum circumcircle of the protrusion structure is less than or equal to 1 mm; and / or,

[0026] The protruding structure is circular in shape; and / or,

[0027] The protrusion height of the protrusion structure is 30%-100% of the thickness of the electrode tab.

[0028] Preferably, along the thickness direction of the tab, at least a portion of the protruding structures of the outer ring tabs are overlapped with the recessed structures located on the same outer ring tab; or, along the thickness direction of the tab, at least a portion of the protruding structures of the outer ring tabs are staggered with the recessed structures located on the same outer ring tab.

[0029] Preferably, the housing includes a surrounding sidewall with an opening at one end; the housing also includes a press-fit portion formed at the end of the sidewall near the opening and recessed into the housing.

[0030] The secondary battery also includes:

[0031] Cover plate, installed in the opening;

[0032] An insulating seal is disposed around the periphery of the cover plate to insulate and seal the cover plate and the housing;

[0033] A collector plate is disposed between the electrode assembly and the cover plate and is electrically connected to the housing. The connecting piece of the collector plate is located on the side of the crimping part facing the electrode assembly and is welded to the crimping part.

[0034] And / or,

[0035] The secondary battery is a cylindrical battery;

[0036] And / or,

[0037] The electrode tab is a positive electrode tab or a negative electrode tab, or the electrode tab includes a positive electrode tab and a negative electrode tab, the positive electrode tab and the negative electrode tab respectively protruding from the two ends of the main body that are disposed opposite to each other along the height direction.

[0038] A battery pack characterized in that it includes a secondary battery as described above.

[0039] An electronic device characterized in that it includes a battery pack as described above.

[0040] The positive and progressive effects of this utility model are as follows:

[0041] In existing technologies, due to the overlapping layers of the stacked tabs, the contact area between the weld and the tabs is small when using laser welding to weld the transition pieces of the wound structure. This easily leads to problems such as incomplete welding or unstable welded structures. In this invention, by providing a recessed structure on the second surface of the flat portion of at least a portion of the outer tabs, the welding contact area can be increased, thereby avoiding problems such as incomplete welding or unstable welded structures, and greatly improving the yield of the battery cell. Furthermore, it can effectively reduce the welding internal resistance, thus achieving the beneficial effect of reducing the battery's internal resistance. Attached Figure Description

[0042] Figure 1 This is a cross-sectional view of a secondary battery according to a preferred embodiment of the present invention.

[0043] Figure 2 for Figure 1 A magnified schematic diagram of part A in the middle.

[0044] Figure 3 This is a three-dimensional structural diagram of the electrode assembly of a secondary battery according to a preferred embodiment of the present invention.

[0045] Figure 4 This is a cross-sectional view of the electrode assembly of a secondary battery according to a preferred embodiment of the present invention.

[0046] Figure 5 This is a partial cross-sectional view of the electrode assembly of a secondary battery according to a preferred embodiment of the present invention.

[0047] Figure 6 for Figure 5 A magnified schematic diagram of part B in the middle section.

[0048] Figure 7 for Figure 6 A magnified schematic diagram of part C in the middle.

[0049] Figure 8 This is a schematic diagram of the structure of the positive electrode sheet of a secondary battery in a preferred embodiment of the present invention when it is not wound.

[0050] Figure 9 This is a partial structural diagram of the positive electrode sheet of a secondary battery in a preferred embodiment of the present invention when it is not wound.

[0051] Figure 10 This is a partial cross-sectional view of the positive electrode sheet of a secondary battery according to a preferred embodiment of the present invention.

[0052] Figure 11This is a schematic diagram of the structure of the negative electrode sheet of a secondary battery in a preferred embodiment of the present invention when it is not wound.

[0053] Figure 12 This is a partial structural diagram of the unwound negative electrode sheet of a secondary battery according to a preferred embodiment of the present invention.

[0054] Figure 13 This is a partial cross-sectional view of the negative electrode sheet of a secondary battery according to a preferred embodiment of the present invention.

[0055] Figure 14 This is a schematic diagram of the battery pack structure according to a preferred embodiment of the present invention.

[0056] Figure 15 This is a schematic diagram of the structure of an electronic device according to a preferred embodiment of the present invention.

[0057] Explanation of reference numerals in the attached figures

[0058] Electronic devices 1000

[0059] Battery pack 100

[0060] Work Department 300

[0061] Box 310

[0062] Box lid 320

[0063] Secondary battery 1

[0064] Casing 10

[0065] Side wall 11

[0066] Opening 12

[0067] end wall 13

[0068] Electrode assembly 20

[0069] 201 winding structure

[0070] Center Hole 2011

[0071] Main body 202

[0072] JE203

[0073] First Surface 2031

[0074] Second Surface 2032

[0075] Pingbe 2033

[0076] Ministry of Establishment 2034

[0077] Outer ring electrode 2035

[0078] Inner ring electrode 2036

[0079] Recessed structure 205

[0080] 206 raised structures

[0081] Positive electrode 21

[0082] Positive current collector 211

[0083] Positive electrode active material layer 2111

[0084] Positive electrode coating area 212

[0085] Uncoated region 213 of positive electrode

[0086] Positive electrode not yet emerging from the electrode tab initiation region 214

[0087] Positive electrode exit loop region 215

[0088] Positive electrode 2151

[0089] Positive pole vertical part 21511

[0090] Positive flat part 21512

[0091] Positive connection region 2152

[0092] Positive electrode not yet exiting electrode tab end region 216

[0093] Positive electrode starting position 217

[0094] Positive electrode end position 218

[0095] Diaphragm 22

[0096] Diaphragm starting position 221

[0097] Diaphragm termination position 222

[0098] Negative electrode 23

[0099] Negative current collector 231

[0100] Negative electrode active material layer 2311

[0101] Negative electrode coating area 232

[0102] 233 Uncoated negative electrode region; 234 Negative electrode tab initiation region; 235 Negative electrode tab region.

[0103] Negative electrode tab 2351

[0104] Negative electrode vertical part 23511

[0105] Negative electrode flat part 23512

[0106] Negative electrode connection region 2352

[0107] The negative electrode has not yet exited the electrode tab, the terminal area is 236, and the starting position of the negative electrode plate is 237.

[0108] Negative electrode end position 238

[0109] Insulation layer 24

[0110] crimping part 30

[0111] Cover plate 40

[0112] Insulating seal 50

[0113] First Collector Disk 61

[0114] Second collection disk 62

[0115] 70 pole

[0116] Height direction H of the winding structure

[0117] Radial R of the wound structure

[0118] The winding direction P of the wound structure

[0119] The length direction of the positive electrode current collector is L1, the length direction of the negative electrode current collector is L2, and the preset direction is Q.

[0120] First preset direction Q1

[0121] Second preset direction Q2

[0122] First included angle α

[0123] Second included angle β

[0124] The maximum circumcircle dimension f1 of the concave structure and the maximum circumcircle dimension f2 of the convex structure

[0125] The thickness t of the electrode

[0126] The depth t1 of the concave structure

[0127] The height t2 of the protrusion structure

[0128] The length a1 of the positive electrode before the tab begins to emerge

[0129] The length a2 of the positive electrode outlet region

[0130] The length a3 of the positive electrode's unexited terminal region

[0131] The length b1 of the negative electrode before the tab begins to emerge

[0132] The length b2 of the negative electrode outlet region

[0133] The length b3 of the negative electrode's unexited terminal area

[0134] The length c of the positive electrode tab

[0135] The length d of the negative electrode tab Detailed Implementation

[0136] The present invention will be described more clearly and completely below with reference to the accompanying drawings, using a preferred embodiment.

[0137] In the existing technology, due to the overlapping of the layers of tabs, when laser welding is used to weld the transition piece of the winding structure, the contact area between the weld and the tab is small, which can easily cause problems such as incomplete welding or unstable welding structure.

[0138] like Figure 1 and Figure 2 As shown, this embodiment provides a secondary battery 1. The secondary battery 1 includes a housing 10 and an electrode assembly 20, the electrode assembly 20 being housed within the housing 10.

[0139] like Figures 3 to 7 As shown, the electrode assembly 20 includes a winding structure 201. The winding structure 201 includes a main body 202 and an electrode tab 203 protruding from one end of the main body 202 along the height direction H of the winding structure 201. The electrode tab 203 is a folded electrode tab 203. The electrode tab 203 is bent toward the central hole 2011 of the winding structure 201. The electrode tab 203 includes a first surface 2031 facing the central hole 2011 and a second surface 2032 away from the central hole 2011. The electrode tab 203 includes a flat portion 2033 and a vertical portion 2034 connected between the main body 202 and the flat portion 2033. The flat portion 2033 is arranged along the radial direction R of the winding structure 201, and the vertical portion 2034 is arranged along the height direction H.

[0140] Among them, the electrode 203 includes an outer ring electrode 2035 located on the outermost ring, and at least a portion of the outer ring electrode 2035 has a recessed structure 205 on the second surface 2032 of the flat portion 2033. The recessed structure 205 is recessed along the height direction H towards the main body portion 202.

[0141] In this way, by providing a recessed structure 205 on the second surface 2032 of the flat portion 2033 of at least a portion of the outer ring tabs 2035, the welding contact area can be expanded, thereby avoiding problems such as poor welding or unstable welding structure, and greatly improving the yield of the cell; and, it can effectively reduce the welding internal resistance, thereby achieving the beneficial effect of reducing the battery internal resistance.

[0142] It should be noted that at least a portion of the outer ring tabs 2035 include two cases: the first case is a portion of the outer ring tabs 2035; the second case is all the outer ring tabs 2035.

[0143] The tab 203 also includes multiple inner tabs 2036 located within the outer tabs 2035. At least a portion of the inner tabs 2036 have recessed structures 205 on the second surface 2032 of their flat portions 2033. Along the height direction H, at least a portion of the recessed structures 205 on the multiple inner tabs 2036 are not obstructed by other stacked tabs 203. By providing recessed structures 205 on more tabs 203, the welding contact area can be further expanded, thereby avoiding problems such as incomplete soldering or unstable welding structures, and greatly improving the yield of the battery cell.

[0144] It should be noted that at least a portion of the inner ring tabs 2036 include two cases: the first case is a portion of the inner ring tabs 2036; the second case is all the inner ring tabs 2036.

[0145] The direction from the main body 202 to the tab 203 is a preset direction Q. The recessed structure 205 is disposed near the outer edge of the tab 203 away from the main body 202 along the preset direction Q, and has a non-zero gap with the outer edge of the tab 203 away from the main body 202 along the preset direction Q, so as to ensure the structural strength of the tab 203 and prevent the tab 203 from tearing.

[0146] Along the winding direction of the winding structure 201, the recessed structure 205 is located in the central region of the second surface 2032, so that the force on the tab 203 is more balanced when the recessed structure 205 is formed, thereby avoiding damage to the structure of the tab 203.

[0147] In this embodiment, a recessed structure 205 is provided on the second surface 2032 of the same electrode 203. However, it is not limited to this, and multiple recessed structures 205 may also be provided on the second surface 2032 of the same electrode 203.

[0148] The recessed structures 205 on the second surface 2032 of the multiple tabs 203 are positioned in the same way so that all the recessed structures 205 are evenly distributed.

[0149] The maximum circumscribed circle size f1 of the recessed structure 205 is less than or equal to 1 mm. By setting the range of values ​​for the maximum circumscribed circle size f1 of the recessed structure 205, the size of the recessed structure 205 is prevented from being too large, which would affect the structural strength of the tab 203.

[0150] Preferably, the recessed structure 205 is circular in shape to minimize its impact on the structural strength of the tab 203 and to facilitate processing. However, it is not limited to this; the recessed structure 205 can also be other shapes, such as rectangular, triangular, etc.

[0151] The recess depth t1 of the recessed structure 205 is 30%-100% of the thickness t of the tab 203. By setting the ratio range of the recess depth t1 to the thickness t of the tab 203, on the one hand, it avoids the recess depth t1 being too small, thus failing to expand the welding contact area; on the other hand, it avoids the recess depth t1 being too large, which would affect the size of the electrode assembly 20 and thus the energy density of the secondary battery 1. Preferably, the recess depth of the recessed structure 205 is 40%-80% of the thickness of the tab 203.

[0152] Furthermore, at least a portion of the outer ring tabs 2035 have a raised structure 206 on the first surface 2031 of the flat portion 2033, which protrudes along the height direction H toward the main body 202. The presence of the raised structure 206 on the first surface 2031 of the flat portion 2033 of at least a portion of the outer ring tabs 2035 further expands the welding contact area, thereby avoiding problems such as incomplete welding or unstable welding structures, significantly improving the yield rate of the battery cell; and effectively reducing the welding internal resistance, thus achieving the beneficial effect of reducing the battery's internal resistance.

[0153] Furthermore, at least a portion of the inner ring tabs 2036 have raised structures 206 on the first surface 2031 of the flat portion 2033. By providing raised structures 206 on more tabs 203, the welding contact area can be further expanded, thereby avoiding problems such as incomplete soldering or unstable welding structure, and greatly improving the yield of the battery cell.

[0154] Preferably, the protruding structure 206 is disposed near the outer edge of the tab 203 away from the main body 202 along the preset direction Q, and has a non-zero gap with the outer edge of the tab 203 away from the main body 202 along the preset direction Q, so as to ensure the structural strength of the tab 203 and prevent the tab 203 from tearing.

[0155] Along the winding direction of the winding structure 201, the protrusion structure 206 is located in the central region of the first surface 2031, so that the force on the tab 203 is more balanced when the protrusion structure 206 is formed, thereby avoiding damage to the structure of the tab 203.

[0156] In this embodiment, a protrusion structure 206 is provided on the first surface 2031 of the same electrode 203. However, it is not limited to this, and multiple protrusion structures 206 may also be provided on the first surface 2031 of the same electrode 203.

[0157] The raised structures 206 on the first surface 2031 of the multiple tabs 203 are positioned in the same way so that all the raised structures 206 are evenly distributed.

[0158] The maximum circumscribed circle size f2 of the protrusion structure 206 is less than or equal to 1 mm. By setting the range of values ​​for the maximum circumscribed circle size f2 of the protrusion structure 206, the size of the protrusion structure 206 is prevented from being too large, which would affect the structural strength of the tab 203.

[0159] Preferably, the protrusion structure 206 is circular in shape to minimize its impact on the structural strength of the tab 203 and to facilitate processing. However, it is not limited to this; the protrusion structure 206 can also be other shapes, such as rectangles, triangles, etc.

[0160] The protrusion height t2 of the protrusion structure 206 is 30%-100% of the thickness t of the tab 203. By setting the ratio range of the protrusion height t2 to the thickness t of the tab 203, on the one hand, it avoids the protrusion height t2 being too small, thus failing to expand the welding contact area; on the other hand, it avoids the protrusion height t2 being too large, thus affecting the size of the electrode assembly 20 and consequently the energy density of the secondary battery 1. Preferably, the protrusion height of the protrusion structure 206 is 40%-80% of the thickness of the tab 203.

[0161] In this embodiment, along the thickness direction of the tab 203, all the protruding structures 206 of the outer ring tabs 2035 are overlapped with the recessed structures 205 located on the same outer ring tab 2035. However, this is not a limitation. In other embodiments, a portion of the protruding structures 206 of the outer ring tabs 2035 may overlap with the recessed structures 205 located on the same outer ring tab 2035; a portion of the protruding structures 206 of the outer ring tabs 2035 and the recessed structures 205 located on the same outer ring tab 2035 may not overlap, but may be staggered or partially overlapped. In other embodiments, along the thickness direction of the tab 203, all the protruding structures 206 of the outer ring tabs 2035 and the recessed structures 205 located on the same outer ring tab 2035 may be staggered.

[0162] The electrode tab 203 includes a positive electrode tab 2151 and a negative electrode tab 2351, which protrude from opposite ends of the main body 202 along the height direction H. However, it is not limited to this; in other embodiments, the electrode tab 203 may be either a positive electrode tab 2151 or a negative electrode tab 2351.

[0163] The positive electrode 21, the separator 22 and the negative electrode 23 are stacked and wound together to form a winding structure 201, which usually has a central hole 2011 in the middle. The axial direction of the central hole 2011 is the axial direction of the winding structure 201. The axial direction of the winding structure 201 is in the same direction as the height direction H of the secondary battery 1 and the height direction H of the winding structure 201.

[0164] like Figures 8-10 As shown, the positive electrode 21 includes a positive current collector 211; along the height direction H, the positive current collector 211 includes a positive electrode coated area 212 covered by the positive electrode active material layer 2111 and a positive electrode uncoated area 213 not covered by the positive electrode active material layer 2111.

[0165] Along the winding direction P of the winding structure 201, the uncoated positive electrode area 213 sequentially includes a positive electrode tabless start area 214, a positive electrode tabless area 215, and a positive electrode tabless end area 216; the positive electrode tabless area 215 includes a positive electrode tab 2151, while neither the positive electrode tabless start area 214 nor the positive electrode tabless end area 216 includes a positive electrode tab 2151. The positive electrode tab 2151 includes a positive electrode flat portion 21512 and a positive electrode upright portion 21511 connecting the main body portion 202 and the positive electrode flat portion 21512. The positive electrode flat portion 21512 is arranged along the radial direction R of the winding structure 201, and the positive electrode upright portion 21511 is arranged along the height direction H. The positive electrode tabless area 215 also includes a positive electrode connection area 2152 connecting the first tab 203 and the positive electrode coated area 212.

[0166] like Figures 11-13 As shown, the negative electrode sheet 23 includes a negative electrode current collector 231; along the height direction H, the negative electrode current collector 231 includes a negative electrode coated area 232 covered by the negative electrode active material layer 2311 and a negative electrode uncoated area 233 not covered by the negative electrode active material layer 2311.

[0167] Along the winding direction P of the winding structure 201, the uncoated negative electrode area 233 sequentially includes a negative electrode tabless start area 234, a negative electrode tabless area 235, and a negative electrode tabless end area 236; the negative electrode tabless area 235 includes a negative electrode tab 2351, while neither the negative electrode tabless start area 234 nor the negative electrode tabless end area 236 includes a negative electrode tab 2351. The negative electrode tab 2351 includes a negative electrode flat portion 23512 and a negative electrode upright portion 23511 connecting the main body portion 202 and the negative electrode flat portion 23512. The negative electrode flat portion 23512 is arranged along the radial direction R of the winding structure 201, and the negative electrode upright portion 23511 is arranged along the height direction H. The negative electrode tabless area 235 also includes a negative electrode connection area 2352 connecting the first tab 203 and the negative electrode coated area 232.

[0168] The first preset direction Q1 is from the main body 202 to the positive electrode tab 2151. Along the first preset direction Q1, the length c of the positive electrode tab 2151 is 4mm-7mm, for example, it can be 4mm, 5mm, 5.5mm, 6mm or 7mm, etc.

[0169] The direction from the main body 202 to the negative electrode tab 2351 is the second preset direction Q2. Along the second preset direction Q2, the length d of the negative electrode tab 2351 is 5mm-8mm, for example, it can be 5mm, 6mm, 6.5mm, 7mm or 8mm, etc.

[0170] In this way, by setting the range of values ​​for the length c of the positive electrode tab 2151 and the length d of the negative electrode tab 2351, a reasonable positive electrode tab stacking area and a negative electrode tab stacking area can be formed. This avoids having too many tab 203 layers in the stacking area, which would reduce the energy density of the battery. On the other hand, if there are too few tab 203 layers in the stacking area, insufficient space may be provided, which may burn surrounding components (such as the separator 22) during the welding process. That is, it will cause thermal impact on the surrounding components and damage them.

[0171] When the positive electrode plate 21 is unfolded, the positive current collector 211 is in a flat state. The extension direction of the positive electrode tab 2151 and the length direction L1 of the positive current collector 211 form a first angle α, which is 30 degrees to 85 degrees. By setting the range of the first angle α, the length of the positive electrode tab 2151 can be extended within a certain range while ensuring the connection strength of the positive electrode tab 2151.

[0172] When the negative electrode plate 23 is unfolded, the negative electrode current collector 231 is in a flat state. The extension direction of the negative electrode tab 2351 and the length direction L2 of the negative electrode current collector 231 form a second included angle β, which is 30 degrees to 85 degrees. By setting the range of the second included angle β, the length of the negative electrode tab 2351 can be extended within a certain range while ensuring the connection strength of the negative electrode tab 2351.

[0173] The thickness of the positive electrode tab 2151 is 12μm-20μm, for example, it can be 12μm, 14μm, 16μm, 17.5μm, 19.5μm, or 20μm. The thickness of the negative electrode tab 2351 is 4μm-11μm, for example, it can be 4μm, 6μm, 7.5μm, 8μm, 9μm, or 11μm. Since the material of the positive electrode tab 2151 is usually aluminum, and the material of the negative electrode tab 2351 is usually copper, the hardness of the positive electrode tab 2151 is higher than that of the negative electrode tab 2351. By setting the thickness range of the positive electrode tab 2151, it is possible to avoid tearing during press-fitting if the thickness is too thin, and to avoid increasing manufacturing costs if the thickness is too thick. By setting the thickness range of the negative electrode tab 2351, the material usage can be minimized while ensuring the installation requirements of the negative electrode tab 2351 are met, achieving the beneficial technical effect of cost saving.

[0174] Along the winding direction P of the winding structure 201, the length a1 of the positive electrode not-exit tab starting area 214 is 400mm-600mm, the length a2 of the positive electrode exit tab area 215 is 3000mm-5000mm, and the length a3 of the positive electrode not-exit tab ending area 216 is 200mm-500mm; along the winding direction P of the winding structure 201, the length b1 of the negative electrode not-exit tab starting area 234 is 300mm-500mm, the length b2 of the negative electrode exit tab area 235 is 3000mm-5000mm, and the length b3 of the negative electrode not-exit tab ending area 236 is 100mm-300mm.

[0175] In this way, by setting the range of values ​​for the following lengths: a1 of the positive electrode not yet exiting the tab start region 214, a2 of the positive electrode exiting the tab region 215, a3 of the positive electrode not yet exiting the tab end region 216, b1 of the negative electrode not yet exiting the tab start region 234, b2 of the negative electrode exiting the tab region 235, and b3 of the negative electrode not yet exiting the tab end region 236, the energy density can be improved and the battery internal resistance can be reduced.

[0176] The ratio of the length a3 of the positive electrode end-of-tab region 216 to the length b3 of the negative electrode end-of-tab region 236 is 1.5-2.5. By setting the range of values ​​for the ratio of a3 to b3, the positive electrode end-of-tab region 216 can be made suitable, ensuring that not only is the number of turns in the positive electrode end-of-tab region 216 greater than that in the negative electrode end-of-tab region 236, but also that both lengths are within a suitable range, thus keeping the battery's internal resistance within a suitable range.

[0177] Along the radial direction R of the wound structure 201, the positive electrode connection region 2152 includes a first side facing away from the central hole 2011 of the wound structure 201 and a second side facing the central hole 2011, wherein at least a portion of the first side and / or the second side is covered with an insulating layer 24. Thus, by covering at least a portion of the first side and / or the second side of the positive electrode connection region 2152 with an insulating layer 24, the risk of deformation of the positive electrode connection region 2152 can be reduced, and the insulation performance of the positive electrode connection region 2152 can be improved, thereby significantly improving the safety and reliability of battery performance. The insulating layer 24 is mainly composed of boehmite and PVDF (polyvinylidene fluoride). The boehmite accounts for 80%; the PVDF accounts for 20%. The thickness of the insulating layer 24 is 1.5μm-2.5μm, for example, it can be 1.5μm, 1.7μm, 2μm, 2.1μm, 2.3μm, or 2.5μm. By setting the thickness range of the insulating layer 24, it is avoided that the coating thickness of the insulating layer 24 is too thin, which would make it difficult to obtain the required electrical insulation and support strength; at the same time, it is avoided that the thickness of the insulating layer 24 is too thick, which would lead to a longer curing time for the coating layer and an increase in the thickness of the overall structure. Preferably, the thickness of the insulating layer 24 is 2μm.

[0178] Please refer to the following: Figure 10 In this embodiment, both the first and second sides of the positive electrode connection region 2152 are covered with an insulating layer 24. However, this is not a limitation. In other embodiments, only the first side of the positive electrode connection region 2152 may be covered with the insulating layer 24, or only the second side of the positive electrode connection region 2152 may be covered with the insulating layer 24. Adjustments can be made according to design requirements.

[0179] In this embodiment, the secondary battery 1 is a cylindrical battery. Cylindrical batteries have advantages such as high energy density, long cycle life, and good safety performance. However, it is not limited to this; in other embodiments, the secondary battery 1 can also be a prismatic battery or other shaped batteries.

[0180] Please refer to the following: Figure 1 and Figure 2In this embodiment, the housing 10 includes a surrounding sidewall 11, one end of which has an opening 12. The housing 10 also includes a crimping portion 30, which is formed at the end of the sidewall 11 near the opening 12 and recessed into the housing 10. The secondary battery 1 also includes a cover plate 40, an insulating seal 50, and a current collector. The cover plate 40 is mounted at the opening 12. The insulating seal 50 surrounds the periphery of the cover plate 40 to insulate and seal the cover plate 40 and the housing 10. The current collector is disposed between the electrode assembly 20 and the cover plate 40 and is electrically connected to the housing 10. The connecting piece of the current collector is located on the side of the crimping portion 30 facing the electrode assembly 20 and is welded to the crimping portion 30. In this way, by setting the connecting piece of the current collector plate to be located on the side of the crimping part 30 facing the electrode assembly 20 and welded to the crimping part 30, that is, the welding area of ​​the current collector plate and the electrode tab 203 is located closer to the electrode assembly 20 than the crimping part 30, the influence of the crimping part 30 on the welding area of ​​the electrode tab 203 and the current collector plate can be prevented, thereby improving the welding strength of the electrode tab 203 and the current collector plate.

[0181] Furthermore, the housing 10 also includes an end wall 13, and a side wall 11 is disposed around the end wall 13 and located at the end of the side wall 11 away from the opening 12. The end wall 13 and the side wall 11 enclose a receiving cavity within the housing 10 for accommodating the electrode assembly 20, electrolyte, and other necessary battery components. The connection between the end wall 13 and the side wall 11 can be achieved in various ways, such as integral stamping, integral casting, or separate welding.

[0182] The secondary battery 1 also includes a terminal post 70, which passes through the end wall 13 and is insulated from the end wall 13.

[0183] The current collector includes a first current collector 61 and a second current collector 62. The first current collector 61 is disposed between the electrode assembly 20 and the end wall 13; the second current collector 62 is disposed between the electrode assembly and the cover plate 40. In this embodiment, as described above, the first current collector 61 corresponds to the positive electrode tab 2151, and the positive electrode tab 2151 is electrically connected to the electrode post 70 through the first current collector 61; the second current collector 62 corresponds to the negative electrode tab 2351, and the negative electrode tab 2351 is electrically connected to the housing 10 through the second current collector 62. However, this is not a limitation. In other embodiments, the first current collector 61 may correspond to the positive electrode tab 2151, and the second current collector 62 may correspond to the negative electrode tab 2351.

[0184] In this embodiment, the welding sequence of the first current collector 61 and the second current collector 62 of the secondary battery 1 to the electrode assembly 20 is as follows: First, place the first current collector 61; then, press the electrode assembly 20 together on both the positive and negative sides (the pressing process can increase the contact between the current collector and the electrode assembly 20 and avoid poor welding); the first current collector 61 is welded using line welding instead of spot welding. This is because the negative electrode tab 2351 is relatively soft, and after two pressings, the second current collector 62 and the electrode assembly 20 will be closer together. Spot welding would cause the diaphragm 22 to be burned due to concentrated heat. Wire welding, with less heat, can avoid burning the diaphragm 22 and causing a short circuit between the positive and negative electrodes; next, place the second current collector 62; press the electrode assembly 20 together on both the positive and negative sides again; finally, weld the second current collector 62.

[0185] like Figure 14 As shown, this utility model also provides a battery pack 100, which includes the aforementioned secondary battery 1. In one embodiment of the battery pack 100, the battery pack 100 includes a housing 310, a cover 320, and multiple secondary batteries 1. The multiple secondary batteries 1 are placed in the housing 310 and connected in series or parallel, or a combination of series and parallel connections. The cover 320 seals the housing 310 to protect the multiple secondary batteries 1. It should be noted that, in addition to the secondary battery 1 of this utility model, the battery pack 100 may also include a battery pack thermal management system, circuit board, etc. The battery pack 100 can be a battery module, a battery pack, an energy storage cabinet, etc.; these will not be described in detail here.

[0186] like Figure 15As shown, this utility model also provides an electronic device 1000, which includes the aforementioned battery pack 100. A working part 300 is electrically connected to the battery pack 100 to obtain electrical power. As an example, the electronic device 1000 is a vehicle, which can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, but are not limited thereto. The working part 300 is the vehicle body, and the battery pack 100 is located at the bottom of the vehicle body, providing electrical power for the vehicle's operation or the operation of its internal electrical components. However, in other embodiments, the electronic device 1000 can also be a mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working part 300 can be a unit component capable of obtaining electrical power from the battery pack 100 and performing corresponding work, such as a fan blade rotation unit or a vacuum cleaner suction unit. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the aforementioned electronic device 1000.

[0187] While specific embodiments of this utility model have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this utility model is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this utility model, but all such changes and modifications fall within the scope of protection of this utility model.

Claims

1. A secondary battery, characterized in that, It includes: case; An electrode assembly is housed within the housing. The electrode assembly includes a winding structure, which includes a main body and an electrode tab protruding from one end of the main body along the height direction of the winding structure. The electrode tab is a folded electrode tab, which is bent toward the central hole of the winding structure. The electrode tab includes a first surface facing the central hole and a second surface away from the central hole. The electrode tab includes a flat portion and a vertical portion connecting the main body and the flat portion. The flat portion is arranged radially along the winding structure, and the vertical portion is arranged along the height direction. The electrode includes an outer ring electrode located at the outermost ring, and at least a portion of the second surface of the flat portion of the outer ring electrode has a recessed structure, which is recessed towards the main body along the height direction.

2. The secondary battery as described in claim 1, characterized in that, The electrode tab also includes multiple inner electrode tabs located within the outer electrode tab, and at least a portion of the second surface of the flat portion of the inner electrode tab is provided with the recessed structure, and along the height direction, at least a portion of the recessed structures located on the multiple inner electrode tabs are not blocked by other stacked electrode tabs.

3. The secondary battery as described in claim 1 or 2, characterized in that, The recessed structure is located near the outer edge of the electrode tab along the predetermined direction from the main body to the tab, away from the main body, and has a non-zero distance between the recessed structure and the outer edge of the electrode tab along the predetermined direction away from the main body; and / or, Along the winding direction of the winding structure, the recessed structure is located in the central region of the second surface; And / or, One or more of the recessed structures are provided on the second surface of the same electrode tab; and / or, The recessed structures on the second surface of the various electrodes are positioned in the same location; and / or, The maximum circumcircle of the recessed structure is less than or equal to 1 mm; and / or, The recessed structure is circular in shape; and / or, The depth of the recessed structure is 30%-100% of the thickness of the tab.

4. The secondary battery as described in claim 1, characterized in that, At least a portion of the first surface of the flat portion of the outer ring tabs is provided with a raised structure, the raised structure protruding towards the main body portion along the height direction.

5. The secondary battery as described in claim 4, characterized in that, The electrode tab also includes multiple inner electrode tabs located within the outer electrode tab, and at least a portion of the first surface of the flat portion of the inner electrode tab is provided with the protruding structure.

6. The secondary battery as described in claim 4 or 5, characterized in that, The protruding structure is positioned near the outer edge of the electrode tab along the predetermined direction, away from the main body, and has a non-zero distance between itself and the outer edge of the electrode tab along the predetermined direction. The direction from the main body to the electrode tab is defined as a preset direction. Along the winding direction of the winding structure, the protrusion structure is located in the central region of the first surface; And / or, One or more of the protrusion structures are provided on the first surface of the same electrode tab; And / or, The protrusions on the first surfaces of the various electrodes are positioned identically; and / or, The maximum circumcircle of the protrusion structure is less than or equal to 1 mm; and / or, The protruding structure is circular in shape; and / or, The protrusion height of the protrusion structure is 30%-100% of the thickness of the electrode tab.

7. The secondary battery as described in claim 4, characterized in that, Along the thickness direction of the electrode tab, at least a portion of the protruding structures of the outer ring electrode tabs are arranged to overlap with the recessed structures located on the same outer ring electrode tab; or, along the thickness direction of the electrode tab, at least a portion of the protruding structures of the outer ring electrode tabs are arranged to be staggered with the recessed structures located on the same outer ring electrode tab.

8. The secondary battery as described in claim 1, characterized in that, The housing includes a surrounding sidewall with an opening at one end; the housing also includes a press-fit portion formed at the end of the sidewall near the opening and recessed into the housing. The secondary battery also includes: Cover plate, installed in the opening; An insulating seal is provided around the periphery of the cover plate to insulate and seal the cover plate and the housing; A collector plate is disposed between the electrode assembly and the cover plate and is electrically connected to the housing. The connecting piece of the collector plate is located on the side of the crimping part facing the electrode assembly and is welded to the crimping part. And / or, The secondary battery is a cylindrical battery; And / or, The electrode tab is a positive electrode tab or a negative electrode tab, or the electrode tab includes a positive electrode tab and a negative electrode tab, the positive electrode tab and the negative electrode tab respectively protruding from the two ends of the main body that are disposed opposite to each other along the height direction.

9. A battery pack, characterized in that, The secondary battery includes any one of claims 1 to 8.

10. An electronic device, characterized in that, Includes the battery pack as described in claim 9.

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