Cylindrical battery cells and battery packs

Abstract

To provide a cylindrical battery cell in which, when a cap and a current collector member are connected by laser penetration welding, the risk of poor welding connection of the current collector member can be reduced and additionally, the availability of an internal space of the battery cell is improved.SOLUTION: A cylindrical battery cell includes a housing, an electrode assembly 120, a cap 140, and a current collector member 130. The housing includes an end wall and a side wall 112 that surrounds the end wall. On one side of the side wall apart from the end wall, an opening part is formed. In the housing, the electrode assembly is disposed and a first tab is provided on one side of the electrode assembly that faces the opening part. On one side where the opening part exists, the cap is disposed and welded and connected to the side wall, thereby sealing the opening part. The current collector member is disposed on one side of the electrode assembly that faces the opening part and the current collector member is welded and connected to the first tab. The current collector member includes a current collector 133 and a thick part 131 welded and connected to the cap.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to the field of battery technology, and more particularly to cylindrical battery cells, battery packs, and electronic devices. [Background technology]

[0002] A cylindrical battery cell mainly comprises a housing, an electrode assembly disposed within the housing, a positive terminal, a current collecting member, and an end cap. In the related art, the cap typically functions as the negative electrode of the cylindrical battery cell. A specific method involves connecting the cap to the current collecting member and the housing. Generally, the thickness of the cap is greater than the thickness of the current collecting member. Therefore, when connecting the cap and the current collecting member by laser penetration welding, welding is difficult and penetration and virtual soldering are likely to occur. This narrows the process window for welding and increases the welding defect rate. Summary of the Invention [Problem to be solved by the invention]

[0003] In consideration of the above-mentioned shortcomings of the related art, the present invention provides a cylindrical battery cell, a battery pack, and an electronic device for solving the technical problems of a narrow process window and a high defect rate in welding, which are encountered when welding is performed to connect a cap and a current collecting member. [Means for solving the problem]

[0004] To achieve the above and other related objects, the present invention provides a cylindrical battery cell including a housing, an electrode assembly, a cap, and a current collecting member. The housing includes an end wall and a side wall surrounding the end wall. An opening is formed on one side of the side wall away from the end wall. An electrode assembly is disposed within the housing, and a first tab is provided on the side of the electrode assembly facing the opening. A cap is disposed on the side where the opening is located and is welded to the side wall to seal the opening. A current collecting member is disposed on the side of the electrode assembly facing the opening, and the current collecting member is welded to the first tab. In the thickness direction of the current collecting member, the current collecting member includes a current collector and a thick portion protruding toward the cap, and the thick portion is welded to the cap.

[0005] In one example of the cylindrical battery cell of the present invention, the thick portion is disposed in the central region of the current collecting member.

[0006] In one example of a cylindrical battery cell of the present invention, the projection of the thick portion of the current collecting member on the electrode assembly in the thickness direction is located in an area with a diameter of 18 mm, with the center of the electrode assembly as the center of the circle.

[0007] In one example of the cylindrical battery cell of the present invention, the current collector and the thick portion are integrally formed.

[0008] In one example of the cylindrical battery cell of the present invention, the current collector and the thick portion are connected by welding.

[0009] In one example of a cylindrical battery cell of the present invention, the thickness of the current collecting member between the end of the current collecting member closest to the electrode assembly and the end where the thick portion is welded to the cap is 0.3 mm to 2 mm.

[0010] In one example of a cylindrical battery cell of the present invention, the thickened portion is located on one side of the current collector away from the electrode assembly.

[0011] In one example of the cylindrical battery cell of the present invention, the thick portion penetrates the current collector in the thickness direction of the current collector.

[0012] In one example of the cylindrical battery cell of the present invention, at least one of the current collecting member and the thick-walled portion is made of low-carbon steel.

[0013] In one example of the cylindrical battery cell of the present invention, the cap has a liquid injection hole at its center, the current collecting member has an opening at its center corresponding to the liquid injection hole, and the cylindrical battery cell further includes a cover plate disposed on the cap, which is welded to the cap to seal the liquid injection hole.

[0014] In one example of the cylindrical battery cell of the present invention, the cover plate covers the welded connection area between the cap and the thickened portion.

[0015] In one example of the cylindrical battery cell of the present invention, the cap includes a recess in the thickness direction of the cap that is recessed toward the current collecting member, and the recess is welded to the thick portion.

[0016] In one example of the cylindrical battery cell of the present invention, the projection of the thick portion covers the projection of the recess in the thickness direction of the current collecting member.

[0017] In one example of a cylindrical battery cell of the present invention, at least a portion of the underside of the cap located at the outer edge is in contact with and welded to the end face of the side wall. Furthermore, an annular groove recessed toward the electrode assembly is further formed at the outer edge of the cap in the thickness direction of the cap. The side wall of the annular groove farther from the center of the cap is in contact with and welded to the inner surface of the side wall.

[0018] In one example of the cylindrical battery cell of the present invention, the bottom wall of the annular groove contacts the current collecting member.

[0019] In one example of the cylindrical battery cell of the present invention, the thickened portion is disposed in the outer edge region of the current collecting member, and the bottom wall of the annular groove is in contact with and welded to the thickened portion.

[0020] In one example of the cylindrical battery cell of the present invention, the cylindrical battery cell further includes an annular cover plate, which is disposed on and covers the annular groove.

[0021] In one example of the cylindrical battery cell of the present invention, the ventilation notch is further disposed in the cap.

[0022] In one example of the cylindrical battery cell of the present invention, a second tab is provided on one side of the electrode assembly facing the end wall, and the cylindrical battery cell further includes an electrode terminal protruding from the outer surface of the end wall, the electrode terminal being electrically connected to the second tab, and a liquid injection hole is provided in the end wall or the electrode terminal.

[0023] The present invention further provides a battery pack including a cylindrical battery cell according to any of the above examples.

[0024] The present invention further provides an electronic device including the above-described battery pack. [Effects of the Invention]

[0025] In the cylindrical battery cell of the present invention, the cap is sealed and welded to the side wall of the housing, and the cap is welded to the current collecting member. This configuration not only eliminates the need for a crimping and sealing process for the housing, reducing the risk of poor welding of the current collecting member during the crimping and sealing process, but also reduces the space occupied by the roll grooves in the housing, thereby improving the utilization of the internal space of the battery cell. At the same time, in the cylindrical battery cell of the present invention, a thickened portion is provided on the current collecting member, increasing the thickness of the current collecting member at the welding position with the cap, thereby reducing the possibility of virtual solder or weld penetration at the welding position during laser penetration welding. This reduces the difficulty of welding the current collecting member and the cap, solving the problems of a narrow welding process window and a reduced defect rate in welding between the cap and the current collecting member. At the same time, the thickened portion effectively reduces the heat generated and transferred to the electrode assembly during the welding process between the current collecting member and the cap, thereby reducing the thermal impact on the electrode assembly. Furthermore, since the thickened portion contacts a portion of the cap, the adhesion at the contact surface between them is improved. In this way, the possibility of virtual solder or missing welds can be further reduced when welding to connect the current collecting member and the cap, thereby improving welding quality and reducing the welding defect rate. [Brief explanation of the drawings]

[0026] In order to more clearly describe the embodiments of the present invention or the technical solutions of the prior art, the drawings necessary for describing the embodiments or related art are briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. Those skilled in the art can obtain other drawings based on these drawings without creative efforts. [Figure 1] 1 is a schematic overall three-dimensional view of an embodiment of a cylindrical battery cell of the present invention. [Figure 2] 1 is a cross-sectional view of the overall structure of one embodiment of a cylindrical battery cell of the present invention. [Figure 3] FIG. 3 is a partial enlarged view of an area A in FIG. 2. [Figure 4] 3 is a schematic diagram showing welding between a current collector and a thick portion in one embodiment of a cylindrical battery cell of the present invention. FIG. [Figure 5] 10 is a schematic diagram showing welding between a current collector and a thick portion in another embodiment of a cylindrical battery cell of the present invention. FIG. [Figure 6] 1 is a schematic structural diagram of a liquid injection hole opening in the center of a cap in one embodiment of a cylindrical battery cell of the present invention. FIG. [Figure 7] FIG. 2 is a schematic three-dimensional view of a cap in one embodiment of a cylindrical battery cell of the present invention. [Figure 8] FIG. 2 is a cross-sectional view showing the overall structure of a cap in one embodiment of a cylindrical battery cell of the present invention. [Figure 9] FIG. 2 is a schematic structural diagram of a thick portion disposed on the outer edge of a current collecting member in one embodiment of a cylindrical battery cell of the present invention. [Figure 10] 10 is a schematic diagram of a liquid injection hole that opens to an end wall side of a housing in one embodiment of a cylindrical battery cell of the present invention. FIG. [Figure 11] 1 is a schematic diagram of the overall structure of one embodiment of a battery pack of the present invention. [Figure 12] 1 is a schematic diagram of a battery pack of the present invention disposed in a vehicle; DETAILED DESCRIPTION OF THE INVENTION

[0027] The following specific examples will be used to describe the implementation of the present invention. Those skilled in the art will readily appreciate other advantages and benefits of the present invention from the content disclosed herein. The present invention can also be implemented or applied through other different specific implementations. Various details of the present specification can also be modified or changed in various ways based on different perspectives and applications without departing from the spirit of the present invention. The following embodiments and features of each embodiment may be combined as long as there is no contradiction between the embodiments. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific embodiments and are not intended to limit the scope of the present invention. In the following examples, test methods that do not specify specific conditions generally employ conventional conditions or conditions recommended by each manufacturer.

[0028] When a numerical range is provided in an embodiment, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected unless otherwise specified in the present invention. Unless otherwise defined, all technical and scientific terms used in the present invention are consistent with the knowledge of the relevant art and the description of the present invention by those skilled in the art. They may be used in conjunction with the methods and methods described in the embodiments of the present invention. Apparatus and materials are similar or equivalent to any methods, apparatus and materials in the relevant art for carrying out the present invention.

[0029] It should be noted that terms such as "upper," "lower," "left," "right," "middle," and "one side" used in this specification are used for convenience of explanation only and are not used to limit the scope. Regarding the feasible scope of the present invention, any change or adjustment of the relative relationship shall be considered to be within the feasible scope of the present invention as long as there is no substantial change in the technical content.

[0030] 1 to 12. The present invention provides a cylindrical battery cell 100, a battery pack, and an electronic device. In the cylindrical battery cell 100, a thickened portion 131 is provided in the current collecting member 130, which increases the thickness of the current collecting member 130 at the welding position with the cap 140, reducing the possibility of virtual solder or weld penetration at the welding position during laser penetration welding. In this way, the difficulty of welding the current collecting member 130 and the cap 140 can be effectively reduced, and the problems of a narrow process window in welding and a reduced defect rate in welding between the cap 140 and the current collecting member 130 can be solved.

[0031] 1 and 2 further illustrate the structure of a cylindrical battery cell 100. The cylindrical battery cell 100 includes a housing 110, an electrode assembly 120, a current collecting member 130, a cap 140, and a cover plate 150. The housing 110 has a cavity formed therein for accommodating the electrode assembly 120, an electrolyte (not shown), and other components. The housing 110 may be open at one end or both ends. The specific dimensions of the housing 110 may be determined according to the specific dimensions of the electrode assembly 120. For example, the specific dimensions of the housing 110 may meet the specifications of 4680, 4695, 46120, and other large cylindrical battery specifications. The housing 110 may be made of various materials, such as copper, iron, aluminum, steel, and aluminum alloys. To prevent the housing 110 from rusting after long-term use, the surface of the housing 110 may be plated with a layer of anti-corrosion material, such as nickel. See FIG. 2. In one example of a cylindrical battery cell 100 of the present invention, the housing 110 includes an end wall 111 and a side wall 112 surrounding the end wall 111. The end wall 111 is a closed end, and the opening 130 on the opposite side of the end wall 111 is an open end. The end wall 111 and the side wall 112 may be integrally formed and connected, or may be formed separately and connected by welding.

[0032] As shown in FIG. 2, the electrode assembly 120 is housed within the housing 110. The electrode assembly 120 is a component within the battery cell where the electrochemical reaction occurs. The housing 110 may contain one or more electrode assemblies 120. The electrode assembly 120 is primarily formed by winding or stacking a positive electrode sheet and a negative electrode sheet, with a separator typically disposed between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode current collector. The positive electrode current collector includes a positive electrode coating region and a positive electrode tab connected to the positive electrode coating region. The positive electrode coating region is coated with the positive electrode active material layer, while the positive electrode tab is not coated with the positive electrode active material layer. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode current collector includes a negative electrode coating region and a negative electrode tab connected to the negative electrode coating region. The negative electrode coating region is coated with a negative electrode active material layer, while the negative electrode tab is not coated with a negative electrode active material layer. Taking a lithium-ion battery as an example, the positive electrode current collector may be made of aluminum, and the positive electrode active material layer may include a positive electrode active material. The positive electrode active material may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode current collector may be made of copper, and the negative electrode active material layer may include a negative electrode active material. The negative electrode active material may be carbon, silicon, or the like. The separator may be made of polypropylene (PP) or polyethylene (PE). To protect and insulate the battery cell, the battery cell may be covered with an insulating film. The insulating film may be synthesized from PP, PE, PET, PVC, or other polymer materials.

[0033] See Figure 2. In one example of a cylindrical battery cell 100 of the present invention, the electrode assembly 120 is sealed and placed in the housing 110. A first tab 121 and a second tab 122 are provided at both ends of the electrode assembly 120 in the longitudinal direction, respectively. The first tab 121 and the second tab 122 have opposite polarities, and the first tab 121 faces the opening 113 of the housing 110. The first tab 121 is a negative electrode tab. Note that in other embodiments, the first tab 121 may be a positive electrode tab, and the second tab 122 may be a negative electrode tab.

[0034] See FIG. 2 . In one example of a cylindrical battery cell 100 of the present invention, a terminal mounting hole 1111 is formed through the end wall 111 of the housing 110. An electrode terminal 170 is disposed in the terminal mounting hole 1111 while being sealed and insulated. The method of disposing the electrode terminal 170 on the end wall 111 is not limited, as long as the electrode terminal 170 is sealed and insulated from the end wall 111. The second tab 122 is disposed on one side of the electrode assembly 120 facing the end wall 111. One end of the electrode terminal 170 may be directly welded to the second tab 122, or may be conductively connected to the second tab 122 via the current collecting member 130. No other specific limitations apply to the present invention.

[0035] Please refer to FIGS. 1 to 3. In one example of a cylindrical battery cell 100 of the present invention, the current collecting member 130 is disposed within the housing 110 and is disposed on one side of the electrode assembly 120 facing the opening 113. The current collecting member 130 is welded to the first tab 121. The specific position where the current collecting member 130 and the first tab 121 are welded and the welding area between them are not limited as long as a stable electrical connection between the current collecting member 130 and the first tab 121 is achieved. The cap 140 is disposed on the opening 113 side of the housing 110 and on one side of the current collecting member 130 away from the electrode assembly 120. The outer edge of the cap 140 is welded to the side wall 112 of the housing 110, thereby sealingly connecting the cap 140 to the opening 113 of the housing 110. The welded connection structure between the outer edge of the cap 140 and the side wall 112 of the housing 110 is not particularly limited as long as it satisfies the requirements for the welded connection between the housing 110 and the cap 140. The current collecting member 130 includes a current collector 133 and a thickened portion 131 protruding toward the cap 140. The thickened portion 131 is electrically connected to the current collector 133. The electrical connection method is not particularly limited, and may be a welding connection, an integral connection, a rivet connection, or any other connection method that satisfies the electrical conductivity requirements. One end of the thickened portion 131 remote from the current collector 133 is welded to one end of the cap 140 facing the electrode assembly 120. In one embodiment of the present invention, the specific location of the thickened portion 131 on the current collector 133 is not limited. For example, the thick portion 131 may be disposed in the central region of the current collector 133, or may be disposed in the outer peripheral region of the current collector 133 as long as the position of the thick portion 131 satisfies the requirements for the strength of the welded connection between the thick portion 131 and the cap 140 and the current distribution. In the present embodiment, the shape of the thick portion 131 is not particularly limited, and may be any shape, such as a disk, annular, or rectangular, as long as the shape of the thick portion 131 satisfies the requirements for the welded connection and the current distribution.

[0036] The assembly of conventional cylindrical battery cells typically requires drilling a roll groove into the side wall of the housing, then welding a current collecting member to the roll groove, and finally crimping a cap onto the opening of the housing to seal it in place. During the crimping process, the welded surface between the roll groove and the current collecting member is easily pulled, damaging the weld and affecting the conductive performance of the cylindrical battery cell. At the same time, the roll groove also occupies space in the radial and axial directions of the housing, reducing the space utilization rate within the battery cell.

[0037] In one embodiment of the present invention, the conductive connection between the electrode assembly 120 and the housing 110 and the fixation of the cap 140 in the opening 113 of the housing 110 are achieved by welding the outer edge of the cap 140 to the sidewall 112 of the housing 110 and welding the cap 140 to the thickened portion 131 of the current collecting member 130. In this configuration, mechanical sealing processes such as roll grooves and crimp sealing are not included in the battery cell assembly process, and therefore the electrical continuity between the current collecting member 130 and the housing 110 is not affected. This not only improves the stability of the current-carrying performance of the cylindrical battery cell 100, but also improves the utilization rate of the internal space of the cylindrical battery cell 100, thereby increasing the volumetric energy density of the battery cell. At the same time, the thickened portion 131 of the current collecting member 130 increases the thickness of the current collecting member 130 at the welding position with the cap 140, thereby reducing the possibility of virtual solder or weld penetration at the welding position during laser penetration welding. In this way, the difficulty of welding the current collecting member 130 and the cap 140 can be effectively reduced, and the problems of a narrow process window for welding and a reduced defect rate for welding the cap 140 and the current collecting member 130 can be solved. At the same time, the configuration of the thickened portion 131 can effectively reduce the heat generated and transferred to the electrode assembly 120 during the welding process between the current collecting member 130 and the cap 140, thereby reducing the thermal impact on the electrode assembly 120. Furthermore, the thickened portion 131 contacts a portion of the area of ​​the cap 140, improving the adhesion at the contact surface between them. In this way, the possibility of virtual solder or weld holes can be further reduced when welding the current collecting member 130 and the cap 140 together, thereby improving the welding quality and reducing the defect rate for welding.

[0038] See FIGS. 3 to 5. In one example of a cylindrical battery cell 100 of the present invention, the thickened portion 131 is located in the central region of the current collecting member 130. The thickened portion 131 may have various shapes, such as a disk shape, an annular shape, or a rectangular shape, as long as the shape satisfies the requirements for the mechanical connection strength and current distribution between the cap 140 and the current collecting member 130. By locating the thickened portion 131 in the central region of the current collector 133, the welding area of ​​the cap 140 corresponding to the thickened portion 131 is also located in the central region of the cap 140. In this way, during the welding process, the entire welding process can be completed by simply moving the welding head back and forth in the central region of the cap 140, thereby obtaining a better welding path and improving the welding efficiency of the cap 140 and the current collecting member 130. In another embodiment of the present invention, the thickened portion 131 has a cylindrical structure, and the thickened portion 131 and the cap 140 are arranged coaxially. With this configuration, it becomes easier to position the thick portion 131 and the cap 140 in the circumferential direction during welding, and the efficiency of welding the cap 140 and the current collecting member 130 is improved.

[0039] See FIG. 3 . In one example of a cylindrical battery cell 100 of the present invention, the current collecting member 130 further includes a tab welding region 134. The tab welding region 134 is disposed around the current collector 133. Furthermore, in the thickness direction of the current collecting member 130, the projection of the thickened portion 131 on the electrode assembly 120 is located in an 18 mm diameter region with the center of the electrode assembly 120 as the center. To improve the stability and reliability of the welded connection between the current collecting member 130 and the electrode assembly 120, the tab welding region 134 is generally located in an area with a thick tab layer. As can be seen from the tab manufacturing process, the 18 mm diameter region with the center of the electrode assembly 120 as the center contains a small number of tab layers and is therefore thin, making this region unsuitable for use as the tab welding region 134. Therefore, by disposing the thickened portion 131 in this region, it is possible to achieve a configuration that separates the tab welding region 134 from the welding region of the cap 140. In this way, the welding area of ​​the tab welding area 134 is not affected, and the tab welding area 134 does not interfere with the welding area of ​​the cap 140. At the same time, the problem of heat concentration during the welding process of the current collecting member 130 can be solved, the deformation of the current collecting member 130 during the welding process can be reduced, and the stability of the conductive connection of the current collecting member 130 can be improved.

[0040] In one embodiment of the present invention, the method of connecting the current collector 133 and the thick portion 131 is not particularly limited, and may be, for example, welding, integral connection, riveting, or the like. Specifically, in one example of a cylindrical battery cell 100 of the present invention, the current collector 133 and the thick portion 131 have an integrally formed structure. The integrally formed structure can be formed by integral pressing or integral casting. Because the current collector 133 and the thick portion 131 are configured as an integral structure, not only can the process of assembling the current collector 133 and the thick portion 131 be omitted, but the assembly efficiency of the cylindrical battery cell 100 is improved, and the connection strength is more reliable.

[0041] 4 and 5. In one example of the cylindrical battery cell 100 of the present invention, instead of being integrally molded, the current collector 133 and the thick portion 131 may be connected by welding. One end of the thick portion 131 remote from the cap 140 is welded to the current collector 133. The welding method is not particularly limited, and any method, such as full penetration welding or seam welding, may be used as long as it satisfies the requirements for stable connection between the current collector 133 and the thick portion 131 and current distribution. Because the current collector 133 and the thick portion 131 are connected by welding, the molding process for the current collector 133 and the thick portion 131 is relatively simple, and a combination of different thicknesses can be used, resulting in relatively good processing adaptability.

[0042] See FIGS. 3 to 5. In one example of the cylindrical battery cell 100 of the present invention, the current collecting member 130 has a maximum thickness T. The thickness T, measured in the thickness direction of the current collecting member 130 between the end of the current collecting member 130 closest to the electrode assembly 120 and the end where the thickened portion 131 is welded to the cap 140, is preferably greater than half the thickness of the cap 140. For example, if the thickness of the cap 140 is 0.6 mm, the thickness T may be 0.3 mm to 2 mm, preferably 0.60 mm to 1.0 mm, and more preferably 0.60 mm to 0.65 mm, such as 0.60 mm, 0.62 mm, or 0.65 mm. If the thickness T is too large, the thickness T will occupy more of the internal space of the housing 110, affecting the volumetric energy density of the battery cell. If the thickness T is too small, it will be difficult to effectively reduce the probability of the current collecting member 130 being welded, which will affect the quality of the weld between the current collecting member 130 and the cap 140. After much process experimentation and research, it was found that by setting the thickness T in the range of 0.60 mm to 0.65 mm, the volumetric energy density of the battery cell is not reduced by occupying a large internal space of the housing 110, and the thin thickness of the current collecting member 130 makes it less likely for welding penetration problems to occur, thereby achieving better welding quality.

[0043] Specifically, various welding connection methods can be used to weld the thick portion 131 and the current collector 133 together. See FIG. 4 . In one example of a cylindrical battery cell 100 of the present invention, the thick portion 131 is located on the side of the current collector 133 that is farther from the electrode assembly 120, and one end of the thick portion 131 that is closer to the current collector 133 is welded to the side of the current collector 133 that is farther from the electrode assembly 120. By employing this weld connection structure, laser penetration welding can be performed between the thick portion 131 and the current collector 133 (the welding direction is as shown by the arrow in FIG. 4 ) before the current collecting member 130 is attached to the housing. This results in a large weld area and excellent stability of the weld connection.

[0044] See FIG. 5. In another example of the cylindrical battery cell 100 of the present invention, a mounting through-hole 1331 is formed along the thickness direction of the current collector 133. One end of the thick portion 131, which is closer to the electrode assembly 120, is inserted into the mounting through-hole 1331, so that the underside of the thick portion 131 is flush with the underside of the current collector 133. This configuration facilitates the configuration and positioning of the thick portion 131 on the current collector 133, and the thick portion 131 and the current collector 133 are connected by seam welding (the welding position is indicated by an arrow in FIG. 5). Observing the weld marks allows intuitive and visual confirmation of the quality of the welded connection, allowing quality problems with the welded connection to be detected in a timely manner and early intervention to prevent risks in the subsequent use of the battery cell.

[0045] Specifically, the cap 140 can be made of various materials, such as copper, iron, aluminum, steel, and aluminum alloys. To facilitate welding, the material of the current collecting member 130 welded to the cap 140 can be changed in conjunction with a change in the material of the cap 140. To ensure the strength and electrical conductivity of the cap 140, in one example of a cylindrical battery cell 100 of the present invention, the cap 140 is made of low-carbon steel. Correspondingly, the material of the current collecting member 130 is also made of low-carbon steel. This configuration facilitates welding between the same materials and improves welding quality. In another embodiment, only the thick-walled portion 131 may be made of low-carbon steel, and the current collector 133 may be made of a flexible metal such as copper. This configuration not only facilitates welding between the thick-walled portion 131 and the cap 140 and ensures welding quality, but also allows the current collector 133 to have a certain degree of flexibility, thereby reducing the impact of deformation stress on the tab welding area during the cap 140 welding process.

[0046] See FIG. 6 . In one example of the cylindrical battery cell 100 of the present invention, a liquid injection hole 160 is disposed in the central region of the cap 140, and an opening 132 is disposed in the central region of the current collecting member 130. The liquid injection hole 160 and the opening 132 are disposed concentrically or approximately concentrically with the central hole 123 of the electrode assembly 120. The cylindrical battery cell 100 further includes a cover plate 150 disposed on the cap 140 to seal the liquid injection hole 160. The method by which the cover plate 150 seals the liquid injection hole 160 is not limited. For example, the cover plate 150 may be connected to the liquid injection hole 160 by adhesive bonding or may be clamped to the liquid injection hole 160 by interference fit. The liquid injection hole 160 may also be sealed by sealing welding, as long as the sealing requirements of the liquid injection hole 160 can be met. This configuration not only allows for convenient and accurate circumferential positioning of the liquid injection hole 160 during liquid injection, but also solves the problem of eccentric liquid injection of the electrode assembly 120 affecting the uniformity of liquid injection. The projection of the liquid injection hole 160 on the end face of the current collecting member 130 along the axial direction of the electrode assembly 120 covers or fits within the opening 132, achieving communication between the liquid injection hole 160 and the opening 132. When electrolyte is injected through the liquid injection hole 160, the electrolyte can flow into the battery cell through the opening 132 and permeate the electrode assembly 120. The liquid injection hole 160 and the opening 132 can be formed in various shapes, such as a circle, a rectangle, or a strip, as long as they can meet the liquid injection requirements. See FIG. 6 . In one embodiment of the present invention, the projection of the liquid injection hole 160 on the end face of the current collecting member 130 fits completely within the opening 132. This configuration prevents the electrolyte from coming into contact with the welded area of ​​the cap 140 and the current collecting member 130 during the injection process, thereby preventing welding slag from the welded area from flowing into the electrode assembly 120 and affecting the injection effect of the electrode assembly 120.

[0047] The diameter of the liquid injection hole 160 may be 1 mm to 14 mm. Considering the operation of the liquid injection process, it is preferable that the diameter of the liquid injection hole 160 is smaller than the diameter of the central hole 123 of the electrode assembly 120. In one example of a cylindrical battery cell 100 of the present invention, the diameter of the liquid injection hole 160 may be any value in the range of 2 mm to 7 mm, such as 2 mm, 3 mm, 4 mm, or 7 mm.

[0048] See FIG. 9 . In one example of a cylindrical battery cell of the present invention, an extension portion is disposed along the circumferential sidewall of the liquid injection hole 160 at one end of the liquid injection hole 160 closest to the electrode assembly 120 along the height direction of the liquid injection hole 160. The extension portion 161 extends downward into the opening 132. The extension portion 161 has an inner hole wall 1611 and an outer hole wall 1612 along the radial direction, with the inner hole wall 1611 being closer to the center of the liquid injection hole 160. The outer hole wall 1612 may be attached to the sidewall of the opening 132, or there may be a gap between the outer hole wall 1612 and the sidewall of the opening 132. In the present invention, the depth to which the extension portion extends into the opening 132 is not limited; the depth may be greater than or less than the height of the opening 132. By providing the extension 161, the height of the sidewall of the liquid injection hole 160 increases, making it easier to temporarily seal the liquid injection hole 160 in the liquid injection step.

[0049] In one example of a cylindrical battery cell 100 of the present invention, the cover plate 150 is disposed on one side of the cap 140 away from the electrode assembly 120. The cover plate 150 covers the welded connection area between the cap 140 and the thickened portion 131. The shape of the cover plate 150 is not particularly limited and may be circular, rectangular, annular, or other shapes as long as it can cover the welded connection area. Because the nickel-plated layer on the surface of the cap 140 in the welded area is damaged by the high temperature of welding, the surface of the cap 140 in the welded area is easily oxidized, making the welded connection area highly susceptible to corrosion and potentially resulting in a failed welded connection. By disposing the cover plate 150 over the welded connection area, the welded connection area is prevented from contacting the surrounding air, reducing the degree of corrosion at the welded connection area. This reduces the probability of failure of the welded connection between the cap 140 and the current collecting member 130 and extends the service life of the cylindrical battery cell 100.

[0050] See Figure 6. In one example of the cylindrical battery cell 100 of the present invention, the liquid injection hole 160 is located in the center of the welded connection area between the cap 140 and the cover plate 150, and the projection of the cover plate 150 on the cap 140 covers the welded connection area. With this configuration, the cover plate 150 can seal the liquid injection hole 160 while simultaneously protecting the weld marks in the welded connection area.

[0051] See Figures 3, 7, and 8. In one example of a cylindrical battery cell 100 of the present invention, the cap 140 includes a cover body 144 and a recess 141. The recess 141 is recessed toward the electrode assembly 120 in the thickness direction of the cap 140. The recess 141 includes a cavity bottom wall 1411, which is welded to one end of the thick portion 131 away from the electrode assembly 120. In one embodiment of the present invention, the relative positions of the recess 141 and the cover body 144 are not particularly limited. For example, the recess 141 may be disposed in the central region of the cover body 144 or in the peripheral region of the cover body 144, as long as the weld connection requirements between the recess 141 and the thick portion 131 can be met. At the same time, the area dimension of the recess 141 is not particularly limited, as long as the weld strength requirements between the cavity bottom wall 1411 and the thick portion 131 can be met. The recess 141 is disposed in the cap 140, so that the cavity bottom wall 1411 contacts the current collecting member 130. With this configuration, a portion of the cap 140 contacts the surface of the current collecting member 130, thereby improving the adhesion of the contact surfaces between the cap 140 and the current collecting member 130. This improves the stability of the welded connection between the cap 140 and the current collecting member 130. At the same time, the recess 141 can form a uniformly distributed area of ​​weld marks on the cap 140, making it easy to timely detect welding position errors that occur during the welding process.

[0052] See Figures 3, 7, and 8. In one embodiment of the present invention, the recess 141 has a disk-like structure and is arranged coaxially with the cap 140. On the one hand, this design eliminates the need to assemble the cap 140 at a predetermined angle in the circumferential direction, and allows the recess 141 to be welded in contact with the lower thick-walled portion 131, thereby improving the assembly efficiency of the cap 140. On the other hand, when the cap 140 and the current collecting member 130 are welded together, a force is applied uniformly in the circumferential direction, thereby reducing stress deformation of the current collecting member 130.

[0053] Specifically, as long as the projection of the recess 141 and the projection of the thickened portion 131 overlap in the thickness direction of the current collecting member 130, a welded connection between the recess 141 and the thickened portion 131 can be achieved. However, preferably, see FIG. 6 . In one example of a cylindrical battery cell 100 of the present invention, the projection of the thickened portion 131 covers the projection of the recess 141 in the thickness direction of the current collecting member 130. This configuration provides a larger welding contact area and improves the stability of the welded connection. At the same time, even if a radial misalignment error occurs between the recess 141 and the thickened portion 131 during the battery cell assembly process, the welding effect between the cap 140 and the current collecting member 130 is not affected.

[0054] See Figures 3, 7, and 8. In one example of a cylindrical battery cell 100 of the present invention, the cap 140 includes a lid body 144 and an annular groove 142. The annular groove 142 is disposed on the outer edge of the cap 140 and is recessed toward the electrode assembly 120 in the thickness direction of the cap 140. The annular groove 142 and the cover 144 are integrally formed. The annular groove 142 includes an annular bottom wall 1421 and a first annular side wall 1422 and a second annular side wall 1423 located on either side of the annular bottom wall 1421 in the radial direction. The first annular side wall 1422 is closer to the center of the end wall 111. A position restricting portion 1424 is disposed at one end of the second annular side wall 1423 away from the annular bottom wall 1421, and the position restricting portion 1424 extends toward one side away from the center of the cap 140. The position restricting portion 1424 may be an integral annular structure connected to the outer peripheral surface of the second annular side wall 1423, or may be a plurality of sheet-like structures spaced apart on the outer peripheral surface of the second annular side wall 1423. The method of connecting the position restricting portion 1424 and the second annular side wall 1423 is not particularly limited, and may be connected by bolting, integral connection, welding, or the like. One end face of the position restricting portion 1424 on the annular bottom wall 1421 side is in contact with and welded to an end face of the side wall 112 of the housing 110, and the outer surface of the second annular side wall 1423 is in contact with and welded to the inner surface of the side wall 112 of the housing 110. The configuration of the position restricting portion 1424 and the second annular side wall 1423 improves the attachment accuracy of the cap 140 in the axial and radial directions of the housing 110, improving the consistency of product assembly accuracy. On the other hand, when laser welding is performed on the outside of the housing 110 where the position restricting portion 1424 radially abuts against the end surface of the side wall 112 of the housing 110, a weld molten pool simultaneously adheres to the position restricting portion 1424 and the second annular side wall 1423, thereby increasing the weld connection area between the cap 140 and the housing 110 and improving the weld connection strength and sealing performance. At the same time, because the molten pool adheres to the second annular side wall 1423, it is possible to prevent weld slag generated when welding the housing 110 from falling inside the housing 110 and affecting the operational performance of the battery cells.

[0055] 3 and 9, in one example of a cylindrical battery cell 100 of the present invention, the outer surface of the annular bottom wall 1421 of the annular groove 142 contacts the circumferential outer edge of the current collecting member 130. With this configuration, the annular bottom wall 1421 generates a downward pressing force on the outer edge of the current collecting member 130, thereby crimping the first tab 121 below the current collecting member 130, limiting local axial displacement of the first tab 121 and preventing the first tab 121 from loosening.

[0056] See Figure 9. Unlike the example of Figure 6, in which the thickened portion 131 is located in the central region of the current collecting member 130, the thickened portion 131 is located in the central region of the current collecting member 130. In one example of a cylindrical battery cell 100 of the present invention, the thickened portion 131 is located in the outer peripheral region of the current collecting member 130, and the annular bottom wall 1421 contacts the upper end surface of the thickened portion 131 and is welded in the region of the annular groove 142, thereby achieving a welded connection between the cap 140 and the current collecting member 130. With this configuration, the welded region between the cover plate 150 and the current collecting member 130 is located in the outer peripheral region of the cap 140. If a ventilation notch 143 is located in the cap 140, the welded region does not affect the opening of the ventilation notch 143, making it easier to release high-pressure gas from the ventilation position.

[0057] See FIG. 9 . The cylindrical battery cell 100 further includes an annular cover plate 190. The annular cover plate 190 is disposed on the annular groove 142 so as to cover the annular groove 142. There are many options for disposing the annular cover plate 190 on the cap 140, such as through adhesive connection or welding connection, as long as the annular groove 142 can be covered and the annular cover plate 190 can be stably connected on the annular groove 142. Disposing the annular cover plate 190 so as to cover the annular groove 142 can reduce the degree of oxidation and corrosion of the welded joint in the annular groove 142, thereby reducing the probability of failure of the welded joint between the cap 140 and the current collecting member 130 and extending the service life of the cylindrical battery cell 100.

[0058] See Figures 8 and 9. In one example of a cylindrical battery cell 100 of the present invention, a vent notch 143 is machined in the cover 144 of the cap 140. The vent notch 143 may have a continuous annular structure or a discontinuous structure. The vent notch 143 is located in a weakened area of ​​the cap 140. When the air pressure inside the cylindrical battery cell 100 exceeds a certain threshold, the position where the vent notch 143 is located breaks, allowing the air pressure inside the cylindrical battery cell 100 to be released through the broken portion, thereby preventing heat from spreading laterally within the cylindrical battery and causing more serious consequences. Preferably, in one embodiment of the present invention, the vent notch 143 has a circular structure and can be arranged coaxially with the cap 140. In this way, the force acting on the vent notch 143 is relatively uniform in the circumferential direction, ensuring that the vent notch 143 opens more timely and accurately.

[0059] See FIGS. 3 and 8. The ventilation notch 143 is located on one side of the cap 140 facing the electrode assembly 120. The ventilation notch 143 is perpendicular to the surface of the cap 140 in the depth direction. The cross section of the ventilation notch 143 may have an inverted cone shape, with one end with a larger diameter facing the electrode assembly 120. The ventilation notch 143 damages the nickel-plated layer on the surface of the cap 140, which makes corrosion more likely to occur at the location of the ventilation notch 143 and affects the opening pressure of the ventilation notch 143. By locating the ventilation notch 143 on the one side facing the electrode assembly 120 so that the ventilation notch 143 is located in the sealed space within the housing 110, the opportunity for the ventilation notch 143 to come into contact with air can be reduced. This reduces the degree of corrosion of the ventilation notch 143 and improves the service life of the ventilation notch 143.

[0060] The liquid injection hole in the above embodiment may be provided on the end wall 111 of the housing 110 instead of on the cap 140, thereby also serving as a means for injecting liquid into the electrode assembly 120. See FIG. 10 . In one embodiment of the present invention, a liquid injection hole 160′ is provided in the electrode terminal 170, and the electrolyte flows into the electrode assembly 120 through the liquid injection hole 160′. A blocking plate 180 is also disposed on the electrode terminal 170. The blocking plate 180 seals the liquid injection hole 160′ to prevent the electrolyte from overflowing through the liquid injection hole 160′. The liquid injection hole 160′ is disposed on the electrode terminal 170. Meanwhile, the liquid injection hole 160′ and the cap 140 are located at both ends of the housing 110, respectively. Therefore, welding slag generated when welding the cap 140 to the current collecting member 130 does not infiltrate the interior of the battery cell through the liquid injection hole 160' and contaminate the electrolyte, thereby improving the service life of the cylindrical battery cell 100. Meanwhile, when the shielding plate 180 seals the liquid injection hole 160' by welding, the welding area is far from the second tab 122, so the thermal impact on the second tab 122 during the welding process is small. At the same time, because the electrode terminal 170 itself has a certain thickness during welding, the electrode terminal 170 reduces the transfer of heat energy generated by welding to the interior of the battery cell, thereby reducing the possibility of thermal decomposition of the electrolyte. In another embodiment, the liquid injection hole may be open in the end wall 111 of the housing 110, which prevents welding slag generated when the cap 140 and the current collecting member 130 are welded from infiltrating the interior of the battery cell through the liquid injection hole and contaminating the electrolyte. In one embodiment of the present invention, the electrode terminal 170 is positively charged and functions as the positive terminal of the cylindrical battery cell 100, and the housing 110 as a whole is negatively charged and functions as the negative terminal of the cylindrical battery cell 100. In other embodiments, the electrode terminal 170 may be negatively charged and functions as the negative terminal of the cylindrical battery cell 100, and the housing 110 may be positively charged as a whole and functions as the positive terminal of the cylindrical battery cell 100.

[0061] Please refer to Fig. 11. In one embodiment of a battery pack 200 of the present invention, the battery pack 200 includes a case body 210 and at least one cylindrical battery cell 100. The case body 210 includes a first case body portion 211 and a second case body portion 212. The first case body portion 211 and the second case body portion 212 cover each other to form an accommodation space. A plurality of cylindrical battery cells 100 are accommodated in the accommodation space. The plurality of cylindrical battery cells 100 may be connected in series and / or parallel.

[0062] See FIG. 12. In one example of the electronic device 300 of the present invention, the electronic device 300 includes an operating unit 310 and a battery pack 200. The operating unit 310 is electrically connected to the battery pack 200 and obtains electrical energy for support. The operating unit 310 may be a unit component that can obtain electrical energy from the battery pack 200 to perform corresponding operations, such as the blade rotation unit of a fan, the dust collection unit of a vacuum cleaner, or the wheel drive unit of an electric vehicle. The electronic device 300 may be a vehicle, a mobile phone, a portable device, a laptop, a boat, a spacecraft, an electric toy, an electric tool, or the like. The vehicle may be a fuel-powered vehicle, a gasoline-powered vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or a long-distance vehicle, or the like. The spacecraft may include an airplane, a rocket, a space shuttle, a spaceship, or the like. The electric toys may include stationary or mobile electric toys such as a game console, an electric car toy, an electric boat toy, and an electric airplane toy. The power tools include metal cutting power tools, grinding power tools, assembly power tools, and railroad power tools, such as power drills, power grinders, power wrenches, power screwdrivers, power hammers, impact drills, concrete vibrators, and planers. The embodiments of the present invention are not particularly limited to the above-mentioned electronic device 300. In one embodiment of the electronic device 300 of the present invention, the electronic device 300 is a vehicle, the operating unit 310 is a vehicle body, and the battery pack 200 is fixedly disposed on the vehicle body to provide driving force to the vehicle and operate the vehicle.

[0063] In the cylindrical battery cell of the present invention, the thickened portion of the current collecting member increases the thickness of the current collecting member at the welding position with the cap, thereby reducing the risk of virtual solder or weld penetration at the welding position during laser penetration welding. This effectively reduces the difficulty of welding the current collecting member to the cap, solves the problem of a narrow welding process window, effectively improves weld quality, and reduces the defect rate of the weld between the cap and the current collecting member. At the same time, the thickened portion effectively reduces the heat generated and transferred to the electrode assembly during the welding process between the current collecting member and the cap, thereby reducing the thermal impact on the electrode assembly. Furthermore, since the thickened portion contacts a portion of the cap, the adhesion at the contact surface between them is improved. This further reduces the possibility of virtual solder or weld holes when welding the current collecting member to the cap, thereby improving weld quality and reducing the defect rate of the weld. Thus, the present invention effectively overcomes practical problems in the prior art and is highly useful and meaningful. The above-described embodiments merely illustrate the principles and effects of the present invention and are not intended to limit the present invention. Anyone with ordinary skill in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by a person with ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present invention shall also be included in the scope of the claims of the present invention. [Industrial Applicability]

[0064] The cylindrical battery cell and battery pack of the present invention can be applied in the field of battery technology. [Explanation of symbols]

[0065] 100: Cylindrical battery cell 110: Housing 111: End wall 1111: Terminal mounting hole 112: Side wall 113: Opening 120: Electrode assembly 121: First tab 122: Second tab 123: Center hole 130: Current collecting member 131: Thick part 132: Opening 133: Current collector 1331: Mounting through hole 134: Tab weld area 140: Cap 141: Recess 142: Annular groove 1421: Annular bottom wall 1422: First annular sidewall 1423: Second annular sidewall 1424: Position regulation part 143: Ventilation notch 144: Lid 150: Lid plate 160, 160': Liquid injection hole 170: Electrode terminal 180: Shield 190: Annular lid plate 200: Battery pack 210: Case body 211: First case body 212: Second case body 300: Electronic equipment 310: Operating unit

Claims

1. a housing including an end wall and a side wall surrounding the end wall, the side wall having an opening formed at one end remote from the end wall; an electrode assembly disposed in the housing and having a first tab on one side facing the opening; a cap disposed on one side where the opening is located and welded to the side wall to seal the opening; a current collecting member disposed on one side of the electrode assembly facing the opening and welded to the first tab; and, the current collecting member includes a current collector and a thick portion protruding toward the cap in a thickness direction of the current collecting member, the thick portion being connected to the cap by welding; The thick portion is disposed in a central region of the current collecting member. Cylindrical battery cell.

2. In the thickness direction of the current collecting member, a projection of the thick portion on the electrode assembly is located in an area having a diameter of 18 mm and a center of the electrode assembly as a circle. The cylindrical battery cell according to claim 1 .

3. The current collector and the thick portion are integrally formed. The cylindrical battery cell according to claim 1 .

4. The current collector and the thick portion are connected by welding. The cylindrical battery cell according to claim 1 .

5. a thickness of the current collecting member between one end of the current collecting member close to the electrode assembly and one end of the current collecting member where the thickened portion is welded to the cap is 0.3 mm to 2 mm in the thickness direction; The cylindrical battery cell according to claim 4 .

6. the thickened portion is disposed on one side of the current collector away from the electrode assembly; The cylindrical battery cell according to claim 4 .

7. the thick portion penetrates the current collector in the thickness direction of the current collector; The cylindrical battery cell according to claim 4 .

8. At least one of the current collector and the thick portion is made of low carbon steel. The cylindrical battery cell according to claim 1 .

9. the center of the cap includes a liquid injection hole, the center of the current collecting member includes an opening corresponding to the liquid injection hole, and the cylindrical battery cell further includes a cover plate disposed on the cap, the cover plate being welded to the cap to seal the liquid injection hole; The cylindrical battery cell according to claim 1 .

10. The cover plate covers the welded connection area between the cap and the thickened portion. The cylindrical battery cell according to claim 9 .

11. the cap includes a recess recessed toward the current collecting member in a thickness direction of the cap, and the recess is welded to the thick portion; The cylindrical battery cell according to claim 1 .

12. a projection of the thick portion covers a projection of the recess in the thickness direction of the current collecting member; The cylindrical battery cell according to claim 11.

13. At least a portion of a lower surface located at an outer edge of the cap is in contact with an end surface of the side wall of the housing and welded to the end surface, and an annular groove recessed toward the electrode assembly is further disposed at the outer edge of the cap in the thickness direction of the cap, the annular groove having an annular side wall spaced from the circular center of the cap, and the annular side wall of the annular groove is in contact with an inner surface of the side wall of the housing and welded to the end surface. The cylindrical battery cell according to claim 1 .

14. The bottom wall of the annular groove contacts the current collecting member. The cylindrical battery cell of claim 13.

15. the thickened portion is disposed in an outer edge region of the current collecting member, and a bottom wall of the annular groove is in contact with and welded to the thickened portion. The cylindrical battery cell of claim 13.

16. The cylindrical battery cell further includes an annular cover plate, the annular cover plate being disposed on the annular groove so as to cover the annular groove. The cylindrical battery cell of claim 13.

17. The cap further includes a ventilation notch. The cylindrical battery cell according to claim 1 .

18. a second tab is provided on one side of the electrode assembly facing the end wall, and the cylindrical battery cell further includes an electrode terminal protruding from the outer surface of the end wall, the electrode terminal being electrically connected to the second tab, and a liquid injection hole is provided on the end wall or the electrode terminal; The cylindrical battery cell according to claim 1 .

19. A battery pack comprising the cylindrical battery cell according to any one of claims 1 to 18.

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