Cylindrical battery, battery pack, electronic device and assembly method of cylindrical battery

Abstract

The invention provides a cylindrical battery, a battery pack, an electronic device and an assembly method of the cylindrical battery. The cylindrical battery comprises a shell and an electrode assembly, the shell comprises a side wall with an opening, and the position, close to the opening, of the side wall comprises a rolling groove sunken towards the interior of the shell. The electrode assembly is arranged in the shell, and the rolling groove limits the displacement of the electrode assembly in the axial direction of the shell; wherein the end, facing the opening, of the electrode assembly comprises a first electrode lug, the first electrode lug is arranged around the axis of the shell, and the first electrode lug is welded to the rolling groove. According to the invention, the technical problem that electric connection failure is easy to occur between the electrode assembly and the shell in the production process of the cylindrical battery can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a cylindrical battery, a battery pack, an electronic device, and an assembly method of the cylindrical battery. Background Art

[0002] In existing cylindrical batteries, a current collecting member is typically placed near the opening of the casing. One end of the current collecting member is welded to the sidewall of the casing, and the other end is electrically connected to the tab of the electrode assembly, thereby achieving an electrical connection between the casing and the electrode assembly. However, during subsequent assembly, the casing opening requires mechanical processing such as grooving and sealing. These processes can cause deformation or fracture in the weld area between the current collecting member and the casing, leading to electrical connection failure and reduced cylindrical battery yield. Summary of the Invention

[0003] The present invention provides a cylindrical battery, a battery pack, an electronic device and an assembly method of a cylindrical battery, so as to improve the technical problem of electrical connection failure between an electrode assembly and a shell during the production process of a cylindrical battery.

[0004] To achieve the above and other related objectives, the present invention provides a cylindrical battery comprising a housing and an electrode assembly. The housing includes a sidewall with an opening, wherein a portion of the sidewall proximate the opening includes a rolling groove recessed into the interior of the housing. The electrode assembly is disposed within the housing, and the rolling groove restricts axial displacement of the electrode assembly within the housing. The end of the electrode assembly facing the opening includes a first tab, which is disposed about the axis of the housing and welded to the rolling groove.

[0005] In an example of a cylindrical battery of the present invention, the electrode assembly includes a negative electrode plate, a separator and a second electrode plate. The negative electrode plate includes a first coated area and a first uncoated area. The first coated area is wound and arranged between the separator and the second electrode plate. The first uncoated area includes a first part, and the first part is wound to form a first electrode ear.

[0006] In an example of the cylindrical battery of the present invention, the ratio of the expanded length of the first portion to the expanded length of the negative electrode sheet is ≥1 / 100, and the height of the first portion is ≤5 mm.

[0007] In an example of a cylindrical battery of the present invention, the first portion is wound and ultrasonically welded to form a first tab; the first tab is electrically connected to the rolling groove by laser welding, and a first weld mark is formed in the welding area.

[0008] In an example of a cylindrical battery of the present invention, along the radial direction of the cylindrical battery, the distance from the point on the rolling groove closest to the axis of the shell to the outer peripheral surface of the shell is A, and the distance from the first weld mark to the outer peripheral surface of the shell is B, where B≤0.5A.

[0009] In an example of the cylindrical battery of the present invention, the first uncoated area also includes a second part, which is wound to form a second pole ear, and the second pole ear is arranged on the side of the first pole ear close to the axis of the shell; the first pole ear is bent toward the axis of the shell and electrically connected to the second pole ear.

[0010] In an example of the cylindrical battery of the present invention, the second tab is formed by a tab flattening process.

[0011] In one example of the cylindrical battery of the present invention, the second tab is formed by a cutting and stacking process.

[0012] In one example of the cylindrical battery of the present invention, the height of the second portion is less than or equal to the height of the first portion.

[0013] In an example of the cylindrical battery of the present invention, the first tab is bent so as to at least partially overlap the outer periphery of the second tab to form an electrical connection with the second tab.

[0014] In an example of the cylindrical battery of the present invention, a conductive sheet is provided between the first tab and the second tab, the conductive sheet is welded to the second tab, and the conductive sheet is at least partially sandwiched between the first tab and the second tab.

[0015] In an example of the cylindrical battery of the present invention, the second tab includes a second weld mark, and the first weld mark and the second weld mark at least partially overlap in the radial direction of the shell.

[0016] In an example of the cylindrical battery of the present invention, before the first tab is bent, a groove is formed between the first tab and the second tab, and after the first tab is bent, at least a portion of the first tab is accommodated in the groove.

[0017] In an example of the cylindrical battery of the present invention, the height of the first tab after bending is h1, the height of the second tab is h2, and h1≤h2.

[0018] The present invention also provides a battery pack, which includes any one of the above cylindrical batteries.

[0019] The present invention also provides an electronic device, which includes the battery pack.

[0020] The present invention also provides a method for assembling a cylindrical battery, wherein the cylindrical battery includes a housing, an electrode assembly, and an end cap, wherein the housing includes a side wall, one end of the side wall has an opening, and the electrode assembly includes a first tab; the assembly method comprises the following steps:

[0021] Install the electrode assembly into the housing through the opening, and form a welding area between the first electrode tab and the side wall near the opening;

[0022] Welding the area to be welded to form a first weld mark between the first electrode tab and the side wall;

[0023] Rolling the sidewall area corresponding to the first weld mark to form a rolling groove, and allowing the rolling groove to limit the axial displacement of the electrode assembly;

[0024] Install the end cap seal over the opening.

[0025] In an example of the assembly method of the present invention, the first electrode tab is ultrasonically welded before the electrode assembly is mounted to the housing.

[0026] In an example of the assembly method of the present invention, the electrode assembly further includes a second electrode tab, and before the end cover is sealed and installed at the opening, the first electrode tab is electrically connected to the second electrode tab.

[0027] The cylindrical battery of the present invention welds the first tab of the electrode assembly directly to the groove of the casing. During the groove process, the first tab can utilize its inherent flexibility to absorb some of the bending and deformation stress, thereby reducing the tensile force exerted on the weld area by the bending and deformation of the first tab during the groove process. This reduces the probability of electrical connection failure between the first tab and the casing, thereby improving the yield and performance of the cylindrical battery. Furthermore, since no current collecting member is required between the electrode assembly and the casing, an internal structural component can be eliminated, which not only reduces production costs but also reduces internal weight, thereby improving the mass energy density of the cylindrical battery. Furthermore, since the tensile force exerted on the weld area by the bending and deformation of the first tab during the groove process is reduced, the probability of metal debris generated in the weld area during the groove process is reduced. This, in turn, reduces the probability of short circuits caused by metal debris falling into the electrode assembly, thereby improving the safety performance of the cylindrical battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a schematic diagram of the overall structure of a cylindrical battery according to an embodiment of the present invention;

[0030] Figure 2 This is a cross-sectional view of the overall structure of an embodiment of a cylindrical battery of the present invention;

[0031] Figure 3 for Figure 2 A local enlarged view of the middle area A;

[0032] Figure 4 for Figure 2A partial enlarged view of the welding position between the first tab and the rolling groove in the embodiment shown;

[0033] Figure 5 This is a schematic diagram of the electrode assembly structure of an example of a cylindrical battery of the present invention;

[0034] Figure 6 Schematic diagram of the expansion of the negative electrode sheet in one embodiment of the cylindrical battery of the present invention;

[0035] Figure 7 Schematic diagram of a winding structure of a cylindrical battery in one embodiment of the present invention, in which a first tab is provided on an electrode assembly;

[0036] Figure 8 Schematic diagram of the expansion of the negative electrode sheet in another embodiment of the cylindrical battery of the present invention;

[0037] Figure 9 This is a schematic diagram of the expansion of the negative electrode sheet in another embodiment of the cylindrical battery of the present invention;

[0038] Figure 10 This is a schematic structural diagram of a cylindrical battery in one embodiment of the present invention, in which a first tab and a second tab are provided on an electrode assembly;

[0039] Figure 11 This is a schematic diagram of a structure in which a conductive sheet is provided between the first tab and the second tab in an embodiment of a cylindrical battery of the present invention;

[0040] Figure 12 Schematic diagram of the structure of a cylindrical battery in one embodiment of the present invention in which the first tab is bent and electrically connected to the second tab;

[0041] Figure 13 Schematic diagram of a cylindrical battery in an embodiment of the present invention, in which a groove is provided between the first tab and the second tab;

[0042] Figure 14 for Figure 13 A schematic diagram of the structure of the electrode assembly in the illustrated embodiment before being installed in the housing and before being grooved;

[0043] Figure 15 for Figure 12 An enlarged view of the partial structure of the electrical connection between the first electrode tab and the second electrode tab in the embodiment shown;

[0044] Figure 16 is a schematic diagram of an example of a battery pack of the present invention;

[0045] Figure 17 is a schematic diagram of an example of an electronic device of the present invention;

[0046] Figure 18 A flow chart of an embodiment of a method for assembling a cylindrical battery according to the present invention;

[0047] Figure 19 This is a schematic structural diagram of an embodiment of a cylindrical battery assembly method according to the present invention, in which an electrode assembly is installed in a housing;

[0048] Figure 20 for Figure 19 A partial enlarged view of point B in the middle.

[0049] Component number description:

[0050] 100, cylindrical battery; 110, housing; 111, side wall; 112, opening; 113, rolling groove; 1131, first groove wall; 114, extension; 115, connection portion; 116, end wall; 120, electrode assembly; 121, positive electrode sheet; 1211, positive electrode current collector; 1212, second coating area; 1213, second uncoated area; 122, separator; 123, negative electrode sheet; 1231, negative electrode current collector; 1232, first coating area; 1233, first uncoated area; 1 234. Inner edge of winding; 1235. Outer edge of winding; 124. Negative electrode tab; 125. Positive electrode tab; 126. First electrode tab; 1261. First weld mark; 127. Second electrode tab; 1271. Second weld mark; 128. Groove; 131. First part; 132. Second part; 140. Conductive sheet; 150. End cover; 160. Sealing ring; 170. Electrode terminal; 200. Battery pack; 210. Case; 220. Case cover; 300. Electronic device; 310. Working part. DETAILED DESCRIPTION

[0051] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following examples and the features in the examples can be combined with each other unless they conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific embodiments, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0052] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those described in the examples of the present invention may also be used to implement the present invention.

[0053] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0054] See also Figures 1 to 20 The present invention provides a cylindrical battery 100, a battery pack 200, an electronic device 300, and an assembly method for the cylindrical battery 100. The cylindrical battery 100 directly welds the first tab 126 of the electrode assembly 120 to the rolling groove 113 of the shell 110. In this way, during the processing of the rolling groove 113, the first tab 126 can use its inherent flexibility to absorb part of the bending deformation stress, thereby weakening the pulling effect on the welding area caused by the bending deformation of the first tab 126 during the rolling groove 113. In this way, the probability of electrical connection failure between the first tab 126 and the shell 110 can be reduced, and the yield and performance of the cylindrical battery 100 can be improved.

[0055] In the present invention, the cylindrical battery 100 may include a lithium-ion battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, etc., and the embodiments of the present invention are not limited thereto.

[0056] See also Figure 1 and Figure 2 , further describing the structure of the cylindrical battery 100 , which includes a housing 110 and an electrode assembly 120 .

[0057] A housing cavity is formed in the shell 110 for accommodating the electrode assembly 120, electrolyte, and other components. The shell 110 may be open at one end or at both ends. The specific dimensions of the shell 110 may be determined based on the specific dimensions of the electrode assembly 120, for example, to meet specifications such as 4680, 4695, and 46120 for large cylindrical batteries. The shell 110 may be made of a variety of materials, such as copper, iron, aluminum, steel, and aluminum alloys. To prevent the shell 110 from rusting during long-term use, a layer of rust-proof material, such as nickel, may be plated on the surface of the shell 110.

[0058] See also Figures 1 to 3In an example of the cylindrical battery 100 of the present invention, the shell 110 is a cylindrical structure. The shell 110 includes an end wall 116 and a side wall 111 surrounding the end wall 116, that is, the shell 110 includes a closed end and an open end. The end wall 116 is the closed end, and the opening 112 opposite to the end wall 116 is the open end. The side wall 111 is formed with a rolling groove 113 that is recessed toward the interior of the shell 110 on the side facing the opening 112. The rolling groove 113 is a recessed structure formed by the side wall 111 being squeezed and deformed toward the interior of the shell 110 under the action of an external mechanical force. The rolling groove 113 can be formed by stamping the side wall 111 through a forming die, or by rolling the side wall 111 through a rolling tool. As long as the rolling groove 113 on the side wall 111 is a recessed structure arranged in a circumferential direction of the side wall 111, it will be sufficient. Please refer to Figure 3 The side wall 111 is further provided with an extension portion 114 extending toward the axis of the shell 110 on the side of the rolling groove 113 close to the opening 112 , and a connecting portion 115 is further provided between the extension portion 114 and the rolling groove 113 , and the extension portion 114 is connected to the rolling groove 113 through the connecting portion 115 .

[0059] See also Figure 2 and Figure 5 The electrode assembly 120 is disposed inside the housing 110. The electrode assembly 120 is the component where the electrochemical reaction occurs in the cylindrical battery 100. The housing 110 may contain one or more electrode assemblies 120. The electrode assembly 120 includes a pole piece and a separator 122, which are wound to form a wound structure. Specifically, in this embodiment, the electrode assembly 120 includes a positive pole piece 121, a separator 122, and a negative pole piece 123 axially wound around the housing 110.

[0060] See also Figures 2 to 5 The positive electrode sheet 121 includes a positive electrode current collector 1211 and a positive electrode active material layer coated on the positive electrode current collector 1211. A second coating area 1212 coated with the positive electrode active material layer and a second uncoated area 1213 not coated with the positive electrode active material layer are formed on the positive electrode current collector 1211. The second coating area 1212 and the second uncoated area 1213 are arranged axially along the shell 110. The second uncoated area 1213 extends to the outside of the diaphragm 122 toward one end in the height direction of the cylindrical battery 100, and is bent toward the axis of the shell 110 to form a stacked positive electrode tab 125.

[0061] See also Figures 2 to 5The negative electrode sheet 123 includes a negative electrode current collector 1231 and a negative electrode active material layer coated on the negative electrode current collector 1231. A first coating area 1232 coated with the negative electrode active material layer and a first uncoated area 1233 not coated with the negative electrode active material layer are formed on the negative electrode current collector 1231. The first coating area 1232 and the first uncoated area 1233 are arranged axially along the shell 110. The first uncoated area 1233 extends to the outside of the diaphragm 122 toward the other end in the height direction of the cylindrical battery 100, and is bent toward the axis of the shell 110 to form a stacked negative electrode tab 124.

[0062] See also Figure 5 The separator 122 is arranged between the positive electrode sheet 121 and the negative electrode sheet 123 to separate the positive electrode active material layer from the negative electrode active material layer. Taking a lithium-ion cylindrical battery as an example, the material of the positive electrode current collector 1211 can be aluminum, and the positive electrode active material layer includes a positive electrode active material. The positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc. The material of the negative electrode current collector 1231 can be copper, and the negative electrode active material layer includes a negative electrode active material. The negative electrode active material can be carbon or silicon, etc. The base material of the separator 122 can be polypropylene (PP) or polyethylene (PE), etc. In order to protect and insulate the battery cell, an insulating film can also be coated on the outside of the battery cell. The insulating film can be synthesized from PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC) or other high molecular polymer materials.

[0063] See also Figure 2 and Figure 5 In an example of a cylindrical battery 100 according to the present invention, the electrode assembly 120 is sealed and mounted within the housing 110. Along the height direction of the cylindrical battery 100, the electrode assembly 120 is disposed between the end wall 116 and the rolling groove 113, and the rolling groove 113 is capable of limiting the axial movement of the electrode assembly 120 between the end wall 116 and the rolling groove 113. The electrode assembly 120 is provided with a positive electrode tab 125 and a negative electrode tab 124 at both ends of the cylindrical battery 100 in the height direction, respectively, wherein the negative electrode tab 124 faces the opening 112, and the positive electrode tab 125 faces the end wall 116. It should be noted that in other embodiments, the positive electrode tab 125 may face the opening 112, and the negative electrode tab 124 may face the end wall 116.

[0064] See also Figure 3 and Figure 4The negative electrode tab 124 includes a first tab 126, which is arranged around the axis of the shell 110 and is welded to the rolling groove 113. The first tab 126 can be arranged around the outer ring of the electrode assembly 120, or around the inner ring of the electrode assembly 120, etc., as long as the conduction requirements between the first tab 126 and the shell 110 are met. When the first tab 126 is welded to the rolling groove 113, the welding can be performed from the outside of the shell 110, that is, the shell 110 is penetrated by welding. Alternatively, the welding can be performed inside the shell 110, that is, the first tab 126 is penetrated by welding. In this embodiment, this welding method is not limited.

[0065] See also Figure 2 and Figure 3 The cylindrical battery 100 also includes an end cap 150, which is arranged at the opening 112. The outer periphery of the end cap 150 is clamped between the extension portion 114, the connecting portion 115 and the rolling groove 113 through a sealing ring 160 to achieve a sealed and fixed connection of the end cap 150 at the opening 112.

[0066] See also Figure 2 The cylindrical battery 100 further includes an electrode terminal 170. A terminal mounting hole is defined through the end wall 116, and the electrode terminal 170 is sealed and insulated within the terminal mounting hole. The electrode assembly 120 has a positive electrode tab 125 on the side facing the end wall 116. One end of the electrode terminal 170 can be directly welded to the positive electrode tab 125 or conductively connected to the positive electrode tab 125 via a current collecting member, without specific limitation.

[0067] In this embodiment, by directly welding the first tab 126 of the electrode assembly 120 to the groove 113 of the housing 110, the first tab 126 can utilize its inherent flexibility to absorb some of the bending and deformation stress during the groove 113 processing process, thereby weakening the pulling effect on the weld area caused by the bending and deformation of the first tab 126 during the groove 113 rolling process. This can reduce the probability of electrical connection failure between the first tab 126 and the housing 110, thereby improving the yield and performance of the cylindrical battery 100. At the same time, since a current collecting member is not required between the electrode assembly 120 and the housing 110, an internal structural component can be saved, which not only reduces production costs but also reduces internal weight, which is conducive to improving the mass energy density of the cylindrical battery 100. Furthermore, since the pulling effect on the welding area caused by the bending and deformation of the first electrode tab 126 during the grooving process is reduced, the probability of metal debris being generated in the welding area during the grooving process can also be reduced, thereby reducing the probability of short circuit caused by metal debris falling into the electrode assembly 120, thereby helping to improve the safety performance of the cylindrical battery 100.

[0068] See also Figure 4 and Figure 6 In an example of a cylindrical battery 100 according to the present invention, the negative electrode tab 123 includes a first coated area 1232 and a first uncoated area 1233. The first coated area 1232 is wound between the separator 122 and the positive electrode tab 121. The first uncoated area 1233 includes a first portion 131, which forms a first electrode tab 126 after winding. The first coated area 1232 is coated with a negative electrode active material. The first electrode tab 126 formed after winding the first portion 131 is the negative electrode tab 124. When the negative electrode tab 123 is unfolded, it includes a wound inner edge 1234 and a wound outer edge 1235. The first portion 131 can be a single long strip structure or a plurality of spaced-apart, localized strip structures. Optionally, in this embodiment, the first portion 131 is a single long strip structure. The location of the first portion 131 on the negative electrode sheet 123 is not limited. For example, it can be located near the inner edge 1234 of the winding of the negative electrode sheet 123, near the outer edge 1235 of the winding of the negative electrode sheet 123, or in the middle region along the length of the negative electrode sheet 123. Optionally, to facilitate welding between the first electrode tab 126 and the rolling groove 113, in this embodiment, the first portion 131 is located near the outer edge 1235 of the winding of the negative electrode sheet 123. This ensures that the first electrode tab 126 formed by the winding of the first portion 131 is located in the outer ring region of the electrode assembly 120, thereby shortening the distance between the first electrode tab 126 and the sidewall 111, facilitating contact between the two for welding.

[0069] By setting the first part 131 on the first uncoated area 1233, the first part 131 is wound to form the first pole ear 126. In this way, by controlling the area size and distribution position of the first part 131 on the first uncoated area 1233, the control of the conduction area and distribution position of the first pole ear 126 on the end face of the electrode assembly 120 can be achieved. Therefore, it is more convenient to regulate the welding position and conduction performance between the first pole ear 126 and the rolling groove 113.

[0070] See also Figure 6In an example of a cylindrical battery 100 according to the present invention, the ratio of the unfolded length L1 of the first portion 131 to the unfolded length L2 of the negative electrode tab 123 satisfies the following conditions: L1 / L2 ≥ 1 / 100. The height of the first portion 131 is h5, and h5 ≤ 5 mm. By ensuring that the ratio of the unfolded length L1 of the first portion 131 to the unfolded length L2 of the negative electrode tab 123 satisfies the following conditions: L1 / L2 ≥ 1 / 100, the first tab 126 formed by winding the first portion 131 can be ensured to have a reasonable number of stacked layers, thereby meeting the current conduction and welding strength requirements between the first tab 126 and the housing 110. The height h5 of the first portion 131 is set to be ≤ 5 mm, which ensures that the first tab 126 formed by winding the first portion 131 has a relatively reasonable height, so that the first tab 126 can meet the area requirement for welding with the side wall 111 before bending, and can also prevent the redundancy of the first tab 126 inside the shell 110 after rolling the groove 113, thereby reducing the occupation of the internal space of the shell 110 and ensuring the volume energy density of the cylindrical battery 100.

[0071] Optionally, see Figure 4 and Figure 7 In one example of a cylindrical battery 100 according to the present invention, after winding, the first portion 131 is ultrasonically welded to form the first tab 126. Compared to traditional welding methods (such as resistance welding, laser welding) or mechanical pressing processes, ultrasonic welding operates at a lower temperature and achieves metal bonding solely through high-frequency vibration friction. Therefore, thermal effects on the active material in the first coating area can be avoided during welding. Furthermore, ultrasonic welding reduces the risk of weld penetration when welding multi-layer wound structures, resulting in a higher welding yield. Laser welding is used to electrically connect the first tab 126 to the rolling groove 113, forming a first weld mark 1261 in the weld area. Specifically, the side of the rolling groove 113 facing the electrode assembly 120 includes a first groove wall 1131. The first tab 126 abuts against the first groove wall 1131 and is welded to form the first weld mark 1261. Laser welding between the first tab 126 and the rolling groove 113 offers high welding efficiency, which helps improve the overall production efficiency of the cylindrical battery 100.

[0072] See also Figure 4In an example of a cylindrical battery 100 according to the present invention, along the radial direction of the cylindrical battery 100, the distance from the point on the groove 113 closest to the axis of the housing 110 to the outer circumferential surface of the housing 110 is A, and the distance from the first weld mark 1261 to the outer circumferential surface of the housing 110 is B, where B ≤ 0.5A. It should be noted that the distance B between the first weld mark 1261 and the outer circumferential surface of the housing 110 specifically refers to the distance between the end of the first weld mark 1261 closest to the sidewall 111 and the outer circumferential surface of the housing 110. This limitation can reduce the tensile force exerted on the first weld mark 1261 by the side of the groove 113 closest to the axis of the housing 110 during tensile deformation during the rolling process, thereby improving the problem of the first tab 126 being easily broken at the first weld mark 1261.

[0073] Optionally, see Figure 4 、 Figure 8 and Figure 10 In an example of the cylindrical battery 100 of the present invention, the first uncoated area 1233 further includes a second portion 132. The second portion 132 is wound to form a second tab 127. The second tab 127 is disposed on a side of the first tab 126 close to the axis of the housing 110. The first tab 126 is bent toward the axis of the housing 110 and electrically connected to the second tab 127. Specifically, when the negative electrode sheet 123 is unfolded, refer to Figure 8 and Figure 9 , the second part 132 is arranged in the area of ​​the negative electrode sheet 123 near the inner edge 1234 of the winding. The end of the second part 132 away from the inner edge 1234 of the winding can be arranged in contact with the first part 131, or it can be arranged in non-contact, and this embodiment does not limit this. The unfolded length of the second part 132 can be greater than the unfolded length of the first part 131, or it can be less than or equal to the unfolded length of the first part 131, and this embodiment does not limit this. When the first pole tab 126 is bent toward the axis of the shell 110 and electrically connected to the second pole tab 127, a stacking contact along the axial direction of the shell 110 can be formed between the first pole tab 126 and the second pole tab 127 to achieve electrical connection between the two. Alternatively, a contact along the radial direction of the shell 110 can be formed between the first pole tab 126 and the second pole tab 127 to achieve electrical connection between the two.

[0074] In this embodiment, by providing a second electrode tab 127 and bending the first electrode tab 126 toward the axis of the shell 110 and then electrically connecting it to the second electrode tab 127, this can not only effectively shorten the current transmission path at the negative terminal and reduce the internal resistance of the cylindrical battery 100, but also increase the load overcurrent capacity of the electrode assembly 120 at the negative terminal, which is beneficial to improving the charge and discharge performance of the cylindrical battery 100.

[0075] In order to improve the compactness of the stacking of the second tabs 127 and reduce the gap between layers, optionally, in an example of the cylindrical battery 100 of the present invention, refer to Figure 7 and Figure 8 The second tab 127 is formed by a tab flattening process. It should be noted that the second tab 127 is formed by a tab flattening process, which means that after the second tab 127 is wound, the second tab 127 is flattened in multiple stages (pressure 50-200N / mm) by a high-precision rolling or stamping device. 2 ), so that multiple layers of metal foil (such as 10 to 30 layers of aluminum foil) are tightly fitted to form a dense flat structure (thickness compression rate 30% to 50%). After the tab flattening process, the gaps between the multi-layer interfaces of the second tab 127 can be effectively eliminated, and the interlayer contact resistance of the second tab 127 can be effectively reduced, thereby reducing the internal resistance of the cylindrical battery 100. At the same time, the second tab 127 has better compactness after the tab flattening process, so when the second tab 127 is subsequently laser welded, the penetration consistency is better and the welding process performance is better.

[0076] Optionally, see Figure 7 and Figure 9 In another example of the cylindrical battery 100 of the present invention, the second tab 127 is formed by a cutting and stacking process. It should be noted that the formation of the second tab 127 by the cutting and stacking process means that before the second tab 127 is wound and formed, the second portion 132 of the negative electrode sheet 123 is pre-cut into multiple equal-width strips (e.g., each strip has a width of 1 to 3 mm) by laser or die-cutting. These strips are then stacked layer by layer during the winding process to form a stepped or parallel second tab 127. Because the stepped strip structure allows current to be drawn from different positions of the second tab 127 in layers, it can reduce the resistance in the lateral direction of the second tab 127, thereby reducing the internal resistance of the cylindrical battery 100. At the same time, because the end faces of the tabs after cutting and stacking are relatively flat, when laser welding the second tab 127, the penetration consistency is good, and the welding process performance is also good.

[0077] Optionally, see Figure 8In one example of the cylindrical battery 100 of the present invention, the height of the second portion 132 is less than or equal to the height of the first portion 131. It should be noted that in this embodiment, the height of the second portion 132 and the height of the first portion 131 refer to the heights of the second portion 132 and the first portion 131 when the negative electrode tab 123 is unfolded. The height of the first portion 131 is h3, and the height of the second portion 132 is h4, with h4 being less than or equal to h3. By ensuring that the height of the second portion 132 is less than or equal to the height of the first portion 131, this arrangement ensures that the first portion 131 has a greater height, thereby providing greater freedom when bending the first tab 126, facilitating bending of the first tab 126 and reducing the probability of bending failure. Furthermore, it prevents the second tab 127 from being too tall, thereby occupying a larger axial space in the housing 110, thereby improving the volumetric energy density of the cylindrical battery 100.

[0078] Optionally, please participate Figure 4 and Figure 7 In an example of a cylindrical battery 100 according to the present invention, the first electrode tab 126 is bent so as to at least partially overlap the outer periphery of the second electrode tab 127, thereby forming an electrical connection with the second electrode tab 127. Since the first electrode tab 126 is bent so as to at least partially overlap the outer periphery of the second electrode tab 127, a stacked arrangement is formed between the first electrode tab 126 and the second electrode tab 127 along the axial direction of the housing 110. This creates a larger contact area in the radial direction of the electrode assembly 120, improves the flow conductivity between the first electrode tab 126 and the second electrode tab 127, and facilitates improved charge and discharge efficiency of the cylindrical battery.

[0079] On the basis of the solution that the first tab 126 is at least partially overlapped with the outer periphery of the second tab 127 after being bent, in order to further improve the stability of the electrical connection between the first tab 126 and the second tab 127, optionally, refer to Figure 11In one example of a cylindrical battery 100 according to the present invention, a conductive sheet 140 is disposed between the first tab 126 and the second tab 127. The conductive sheet 140 is welded to the second tab 127, and at least partially sandwiched between the first tab 126 and the second tab 127. The shape of the conductive sheet 140 is not limited, and can be a circular ring, a flat sheet, a long strip, etc. The conductive sheet 140 can be made of any conductive material that can be welded to the second tab 127, such as copper, aluminum, or a copper alloy. Optionally, in this embodiment, the conductive sheet 140 is a circular sheet structure, coaxially disposed with the second tab 127, and covers the upper surface of the second tab 127. The central region of the conductive sheet 140 is welded to the second tab 127, and the outer periphery of the conductive sheet 140 is sandwiched between the first tab 126 and the second tab 127. The conductive sheet 140 can be welded to the first tab 126 to achieve electrical connection between the conductive sheet 140 and the first tab 126. The conductive sheet 140 can also be in contact with the first tab 126 through the clamping force of the first tab 126 and the second tab 127 to achieve electrical connection between the conductive sheet 140 and the first tab 126.

[0080] By providing a conductive sheet 140 and welding the conductive sheet 140 to the second pole tab 127, and the conductive sheet 140 is at least partially sandwiched between the first pole tab 126 and the second pole tab 127, the current transmitted on the second pole tab 127 can be collected on the conductive sheet 140 and then transmitted to the first pole tab 126 through the conductive sheet 140, thereby improving the stability of the electrical connection between the second pole tab 127 and the first pole tab 126.

[0081] To further improve the flow conductivity between the first and second tabs 126, 127, in one embodiment of the cylindrical battery 100 of the present invention, the second tab 127 optionally includes a second weld mark 1271. The first and second weld marks 1261, 1271 at least partially overlap in the radial direction of the housing 110. Since the second tab 127 has a multi-layer stacked structure, gaps inevitably exist between adjacent stacked layers. Therefore, providing the second weld mark 1271 on the second tab 127 allows for the formation of a stable intermetallic compound layer by welding and melting on the second tab 127. This further improves the flow conductivity stability and current carrying capacity of the second tab 127 compared to simple mechanical crimping. The second weld mark 1271 can have any shape on the second tab 127, for example, it can be distributed in a linear, arc-shaped, or dotted pattern. As long as the first and second weld marks 1261, 1271 at least partially overlap in the radial direction of the housing 110, the shape of the second weld mark 1271 is not limited in this embodiment. Optionally, in this embodiment, the second weld mark 1271 is a linear structure extending in the radial direction of the housing 110. The first weld mark 1261 is also a linear structure extending in the radial direction of the housing 110. This arrangement allows for a larger overlap area between the first weld mark 1261 and the second weld mark 1271. In this embodiment, by at least partially overlapping the first weld mark 1261 and the second weld mark 1271 in the radial direction of the housing 110, a more stable electrical connection is achieved between the first electrode tab 126 and the second electrode tab 127, further improving the stability of the flow conductivity between the electrode assembly 120 and the housing 110.

[0082] Optionally, see Figures 12 to 14In an example of the cylindrical battery 100 of the present invention, before the first pole tab 126 is bent, a groove 128 is formed between the first pole tab 126 and the second pole tab 127. After the first pole tab 126 is bent, it is at least partially accommodated in the groove 128. Specifically, the groove 128 is an annular structure, with the first pole tab 126 forming the outer annular wall of the groove 128 and the second pole tab 127 forming the inner annular wall of the groove 128. After the first pole tab 126 is bent, it can be partially accommodated in the groove 128, that is, the surface of the first pole tab 126 facing the rolling groove 113 after being bent protrudes from the surface of the second pole tab 127. After the first pole tab 126 is bent, it can also be fully accommodated in the groove 128, that is, the surface of the first pole tab 126 facing the rolling groove 113 after being bent is flush with or lower than the surface of the second pole tab 127. It should be noted that, in order to achieve electrical connection between the bent first tab 126 and the second tab 127, in this embodiment, the bent first tab 126 contacts and conducts electricity with the second tab 127 along the radial direction of the housing 110. By providing the groove 128 and allowing the bent first tab 126 to be at least partially accommodated within the groove 128, the axial space of the housing 110 occupied by the bent first tab 126 can be reduced, thereby facilitating an improvement in the volumetric energy density of the cylindrical battery 100.

[0083] Based on the solution that the first tab 126 is at least partially accommodated in the groove 128 after being bent, optionally, refer to Figure 15 In an example of a cylindrical battery 100 according to the present invention, the height of the bent first tab 126 is h1, the height of the second tab 127 is h2, and h1 ≤ h2. This arrangement can further reduce the height of the bent first tab 126 and the axial space occupied by the bent first tab 126 within the housing 110, thereby further improving the volumetric energy density of the cylindrical battery 100.

[0084] See also Figure 16 The present invention further provides a battery pack 200, which includes any of the cylindrical batteries 100 described above. In one embodiment of the battery pack 200 of the present invention, the battery pack 200 includes a housing 210, a housing cover 220, and a plurality of cylindrical batteries 100. The plurality of cylindrical batteries 100 are placed in the housing 210 and are connected in series or in parallel, or in a mixture of series and parallel. The housing cover 220 is sealed on the housing 210 to protect the plurality of cylindrical batteries 100. It should be noted that, in addition to the cylindrical batteries 100 of the present invention, the battery pack 200 may also include a battery pack 200 thermal management system, a circuit board, and other components. The battery pack 200 may be a battery module, a battery pack, an energy storage cabinet, etc.; these will not be described in detail here.

[0085] See also Figure 17The present invention also provides an electronic device 300, which includes the above-mentioned battery pack 200. The working part 310 is electrically connected to the battery pack 200 to obtain electrical energy support. As an example, the electronic device 300 is a vehicle, which can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc., but is not limited to this. The working part 310 is the vehicle body, and the battery pack 200 is arranged at the bottom of the vehicle body and provides electrical energy support for the vehicle's driving or the operation of electrical components in the vehicle. However, in some other embodiments, the electronic device 300 can also be a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. Spacecraft include airplanes, rockets, space shuttles and spacecraft, etc. The working part 310 can be a unit component that can obtain electrical energy from the battery pack 200 and perform corresponding work, such as a fan blade rotation unit, a vacuum cleaner's dust collection unit, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys. Electric tools include metal cutting tools, grinding tools, assembly tools, and railway tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers. The present embodiment does not impose any particular limitation on the electronic device 300.

[0086] See also Figure 18 The present invention also provides an assembly method for a cylindrical battery 100, which is used to manufacture the cylindrical battery 100 in the above embodiment. The cylindrical battery 100 includes a housing 110, an electrode assembly 120, and an end cap 150. The housing 110 includes a sidewall 111, one end of which has an opening 112. The electrode assembly 120 includes a first tab 126. The assembly method includes the following steps:

[0087] S1. Install the electrode assembly 120 into the housing 110 through the opening 112 , and form a welding area between the first electrode tab 126 and the sidewall 111 near the opening 112 .

[0088] See also Figure 19 and Figure 20 As long as the electrode assembly 120 can be installed into the housing 110 through the opening 112, the specific installation method of the electrode assembly 120 is not limited. For example, it can be installed manually or by a robot. The first electrode tab 126 is located on the side of the electrode assembly 120 facing the opening 112. The first electrode tab 126 and the sidewall 111 can be overlapped at an angle to form a weld area. The first electrode tab 126 and the sidewall 111 can also overlap vertically to form a weld area.

[0089] S2 . Welding the area to be welded to form a first weld mark 1261 between the first electrode tab 126 and the side wall 111 .

[0090] See also Figure 19 and Figure 20 When welding the area to be welded, welding can be performed on the inside of the shell 110 or on the outside of the shell 110, as long as a first weld mark 1261 that meets the strength requirements can be formed between the first electrode tab 126 and the side wall 111.

[0091] S3. Rolling is performed on the sidewall 111 area corresponding to the first weld mark 1261 to form a rolling groove 113 , and the rolling groove 113 limits the axial displacement of the electrode assembly 120 .

[0092] The groove 113 can be formed in any manner. For example, the groove 113 can be formed by machining the side wall 111 with a groove cutting tool, or by stamping the side wall 111 with a forming die. The cross-sectional shape of the groove 113 can be any shape that meets the requirements of the application, such as a rectangle, a square, or a trapezoid, and is not specifically limited in the present invention.

[0093] S4. Install the end cover 150 at the opening 112 in a sealed manner.

[0094] See also Figure 3 and Figure 4 The outer periphery of the end cover 150 is overlapped on the surface of the rolling groove 113 facing the opening 112 through the sealing ring 160, and then the opening 112 area of ​​the side wall 111 is sealed, so that the end cover 150 is sealed and installed at the opening 112 position of the shell 110.

[0095] In the assembly steps of the cylindrical battery 100 described above, after the electrode assembly 120 is assembled into the interior of the housing 110, the first electrode tab 126 and the side wall 111 are overlapped to form a to-be-welded area. By welding the to-be-welded area, the first electrode tab 126 and the side wall 111 are welded, thereby achieving an electrical connection between the electrode assembly 120 and the housing 110. Throughout the assembly steps, only one welding step, between the first electrode tab 126 and the side wall 111, is required to electrically connect the electrode assembly 120 to the housing 110. Compared to assembly methods that include current collecting components, this assembly method can save assembly steps, improve assembly efficiency, and thus reduce the production cost of the cylindrical battery 100. At the same time, since the first pole tab 126 can use its inherent flexibility to absorb part of the bending deformation stress during the groove rolling 113 process, the pulling effect on the welding area caused by the bending deformation of the first pole tab 126 during the groove rolling 113 process can be weakened. This can reduce the probability of electrical connection failure between the first pole tab 126 and the shell 110, and improve the yield and performance of the cylindrical battery 100.

[0096] See also Figure 7 In an example of the assembly method of the present invention, before the electrode assembly 120 is mounted to the housing 110 , the first electrode tab 126 is ultrasonically welded.

[0097] By using ultrasonic welding, the interlayer spacing of the first electrode tab 126 can be reduced, thereby improving the flow conductivity of the first electrode tab 126. Furthermore, after the first electrode tab 126 is ultrasonically welded, the vibration energy of the ultrasonic welding head forms periodic micro-protrusions on the surface of the first electrode tab 126. These micro-protrusions can increase the absorption rate of the first electrode tab 126 to the laser, thereby facilitating the subsequent laser welding between the first electrode tab 126 and the sidewall 111.

[0098] See also Figure 3 and Figure 7 In an example of the assembly method of the present invention, the electrode assembly 120 further includes a second electrode tab 127 . Before the end cap 150 is sealed and installed at the opening 112 , the first electrode tab 126 is electrically connected to the second electrode tab 127 .

[0099] The electrical connection between the first electrode tab 126 and the second electrode tab 127 is not limited. For example, the first electrode tab 126 can be bent to form a stack with the second electrode tab 127 along the axial direction of the housing 110, thereby achieving electrical connection. Alternatively, the first electrode tab 126 can be bent to contact the second electrode tab 127 along the radial direction of the housing 110, thereby achieving electrical connection. Alternatively, another conductive member can be provided between the first electrode tab 126 and the second electrode tab 127, and the conductive member can be used to electrically connect the first electrode tab 126 and the second electrode tab 127. By providing the second electrode tab 127 and electrically connecting the first electrode tab 126 and the second electrode tab 127 before the end cap 150 is sealed and installed in the opening 112, this not only effectively shortens the current transmission path at the negative terminal, reducing the internal resistance of the cylindrical battery 100, but also increases the load overcurrent capacity of the electrode assembly 120 at the negative terminal, which is beneficial for improving the charge and discharge performance of the cylindrical battery 100.

[0100] The cylindrical battery of the present invention welds the first tab of the electrode assembly directly to the groove of the casing. During the groove process, the first tab can utilize its inherent flexibility to absorb some of the bending and deformation stress, thereby reducing the tensile force exerted on the weld area by the bending and deformation of the first tab during the groove process. This reduces the probability of electrical connection failure between the first tab and the casing, thereby improving the yield and performance of the cylindrical battery. Furthermore, since no current collecting member is required between the electrode assembly and the casing, an internal structural component can be eliminated, reducing production costs and internal weight, thereby improving the mass energy density of the cylindrical battery. Furthermore, since the tensile force exerted on the weld area by the bending and deformation of the first tab during the groove process is reduced, the probability of metal debris generated in the weld area during the groove process is reduced. This, in turn, reduces the probability of short circuits caused by metal debris falling into the electrode assembly, thereby improving the safety performance of the cylindrical battery. Therefore, the present invention effectively overcomes several practical problems of the prior art and has high utility and practical significance. The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by persons skilled in the art without departing from the spirit and technical concepts disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A cylindrical battery, characterized in that: include: The housing comprises a side wall having an opening, wherein a position of the side wall adjacent to the opening comprises a rolling groove recessed toward an interior of the housing; An electrode assembly is disposed in the housing, wherein the rolling groove limits displacement of the electrode assembly in the axial direction of the housing; The end of the electrode assembly facing the opening includes a first electrode tab, the first electrode tab is arranged around the axis of the shell, and the first electrode tab is welded to the rolling groove.

2. The cylindrical battery according to claim 1, characterized in that: The electrode assembly includes a positive electrode sheet, a separator and a negative electrode sheet. The positive electrode sheet includes a first coated area and a first uncoated area. The first coated area is wound and arranged between the separator and the positive electrode sheet. The first uncoated area includes a first part, and the first part is wound to form the first electrode tab.

3. The cylindrical battery according to claim 2, characterized in that: The ratio of the expanded length of the first portion to the expanded length of the negative electrode sheet is ≥1 / 100, and the height of the first portion is ≤5 mm.

4. The cylindrical battery according to claim 2, characterized in that: After the first portion is wound, ultrasonic welding is performed to form the first pole tab; the first pole tab is electrically connected to the rolling groove by laser welding, and a first weld mark is formed in the welding area.

5. The cylindrical battery according to claim 4, characterized in that: Along the radial direction of the cylindrical battery, the distance from the point on the rolling groove closest to the axis of the shell to the outer circumferential surface of the shell is A, and the distance from the first weld mark to the outer circumferential surface of the shell is B, where B≤0.5A.

6. The cylindrical battery according to claim 2, characterized in that: The first uncoated area further includes a second portion, which is wound to form the second pole tab. The second pole tab is arranged on a side of the first pole tab close to the axis of the shell. The first pole tab is bent toward the axis of the shell and electrically connected to the second pole tab.

7. The cylindrical battery according to claim 6, characterized in that: The second tab is formed by a tab flattening process.

8. The cylindrical battery according to claim 6, characterized in that: The second electrode tab is formed by a cutting and laminating process.

9. The cylindrical battery according to claim 6, characterized in that: The height of the second portion is less than or equal to the height of the first portion.

10. The cylindrical battery according to claim 6, characterized in that: After being bent, the first electrode tab is at least partially overlapped with the outer periphery of the second electrode tab to form an electrical connection with the second electrode tab.

11. The cylindrical battery according to any one of claims 6 to 10, characterized in that: A conductive sheet is provided between the first electrode tab and the second electrode tab, the conductive sheet is welded to the second electrode tab, and the conductive sheet is at least partially sandwiched between the first electrode tab and the second electrode tab.

12. The cylindrical battery according to any one of claims 6 to 10, characterized in that: The second electrode tab includes a second weld print, and the first weld print and the second weld print at least partially overlap in a radial direction of the housing.

13. The cylindrical battery according to claim 6, characterized in that: Before the first electrode tab is bent, a groove is formed between the first electrode tab and the second electrode tab. After the first electrode tab is bent, at least a portion of the first electrode tab is accommodated in the groove.

14. The cylindrical battery according to claim 13, characterized in that: The height of the first tab after bending is h1, the height of the second tab is h2, and h1≤h2.

15. A battery pack, characterized in that: A cylindrical battery comprising the cylindrical battery according to any one of claims 1 to 14.

16. An electronic device, characterized in that: A battery pack comprising the battery pack of claim 15.

17. A method for assembling a cylindrical battery, the cylindrical battery comprising a housing, an electrode assembly, and an end cap, the housing comprising a sidewall having an opening at one end, and the electrode assembly comprising a first tab; It is characterized by: The assembly method comprises the following steps: Installing the electrode assembly into the housing through the opening, and forming a welding area between the first tab and the side wall near the opening; Welding the area to be welded to form a first weld mark between the first electrode tab and the side wall; Rolling the sidewall area corresponding to the first weld mark to form a rolling groove, and allowing the rolling groove to limit the axial displacement of the electrode assembly; The end cap is sealed and installed at the opening.

18. The assembly method according to claim 17, characterized in that: Before the electrode assembly is mounted on the housing, ultrasonic welding is first performed on the first electrode tab.

19. The assembly method according to claim 17, characterized in that: The electrode assembly further includes a second electrode tab. Before the end cap is sealed and installed at the opening, the first electrode tab is electrically connected to the second electrode tab.

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