Cylindrical battery cell and battery pack

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 includes a housing, an electrode assembly disposed in the housing, a positive terminal, a current collecting member, and an end cap. In the related art, the cap usually functions as the negative electrode of the cylindrical battery cell. A specific method is to connect 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, the welding is difficult and welding penetration and virtual soldering are likely to occur. Therefore, the process window in welding is narrowed, and the defect rate of welding is high. 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 to solve the technical problems of low process window and high defect rate in welding encountered when welding is performed to connect a cap and a current collecting member. [Means for solving the problem]

[0004] In order 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 remote from the end wall. An electrode assembly is disposed within the housing, and a first tab is provided on the one side of the electrode assembly facing the opening. A cap is disposed on the one side where the opening is located and is welded and connected to the side wall to seal the opening. A current collecting member is disposed on the one side of the electrode assembly facing the opening, and the current collecting member is welded and connected to the first tab. In a 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 and connected to the cap.

[0005] In one example of a 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, the center of which is the center of the electrode assembly.

[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 in the thickness direction of the current collecting member between one end of the current collecting member close to the electrode assembly and one 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 a 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 portion is made of low carbon steel.

[0013] In one example of the cylindrical battery cell of the present invention, the cap includes a liquid injection hole at its center, an opening corresponding to the liquid injection hole is formed at the center of the current collecting member, 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.

[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 a 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, in the thickness direction of the current collecting member, the projection of the thick portion covers the projection of the recess.

[0017] In one embodiment of the cylindrical battery cell of the present invention, at least a portion of the lower surface located at the outer edge of the cap is in contact with and welded to the end face of the side wall. In addition, an annular groove recessed toward the electrode assembly is further provided at the outer edge of the cap in the thickness direction of the cap. The side wall of the annular groove far from the circular 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, a 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 is 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 battery pack described above. Effect 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 omits the crimp sealing process of the housing, and reduces the risk of poor welding connection of the current collecting member in the crimp sealing process, but also reduces the space occupied by the roll groove in the housing, thereby improving the utilization rate of the internal space of the battery cell. At the same time, in the cylindrical battery cell of the present invention, the current collecting member is provided with a thickened portion, which increases 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. In this way, the difficulty of welding between the current collecting member and the cap can be reduced, and the problems of a low process window in welding and a reduced defect rate of welding between the cap and the current collecting member can be solved. At the same time, the configuration of the thickened portion can effectively reduce the heat generated and transmitted 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. In addition, since the thickened portion is in contact with a part of the area of ​​the cap, the adhesion at the contact surface between them is better. In this way, the possibility of virtual solder or weld holes can be further reduced when welding to connect the current collecting member and the cap, thereby improving the welding quality and reducing the welding defect rate. [Brief description 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 an overall schematic three-dimensional view of one embodiment of a cylindrical battery cell of the present invention; [Diagram 2] 1 is a cross-sectional view of the overall structure of one embodiment of a cylindrical battery cell of the present invention. [Diagram 3] FIG. 3 is a partial enlarged view of region A in FIG. 2. [Figure 4] 5 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. [Diagram 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 at the outer edge of a current collecting member in one embodiment of a cylindrical battery cell of the present invention. [Figure 10] 4 is a schematic diagram of a liquid injection hole opening on 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 PREFERRED EMBODIMENTS

[0027] The present invention will be described below with reference to 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 implementations. Various details of this 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. In addition, the following embodiments and the characteristic parts in each embodiment may be combined as long as there is no contradiction between each embodiment. 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 usually adopt 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 end points of each numerical range and any value between the two end points can be selected unless otherwise stated 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 with the methods and methods described in the embodiments of the present invention. The devices and materials are similar or equivalent to any methods, devices and materials of the relevant art for carrying out the present invention.

[0029] It should be noted that terms such as "upper", "lower", "left", "right", "middle", "one side" and the like are used for convenience of explanation only and are not used to limit the scope. As for the scope of the present invention, any change or adjustment of the relative relationship is also considered to be within the 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, 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 low process window in welding and a reduction in the defect rate of welding between the cap 140 and the current collecting member 130 can be solved.

[0031] 1 and 2 further illustrate the structure of the 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 is formed with a receiving cavity for receiving the electrode assembly 120, an electrolyte (not shown), and other components. The housing 110 may be open at one end or open at 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 specifications of large cylindrical batteries. The housing 110 may be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order 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-rust 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 an opening 130 opposite 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 in the housing 110. The electrode assembly 120 is a component in a battery cell where an electrochemical reaction occurs. The housing 110 may include one or more electrode assemblies 120. The electrode assembly 120 is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and a separator is usually disposed between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode collector. The positive electrode collector includes a positive electrode coating area and a positive electrode tab connected to the positive electrode coating area. The positive electrode coating area is coated with the positive electrode active material layer, and the positive electrode tab is not coated with the positive electrode active material layer. The negative electrode sheet includes a negative electrode collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode 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, and the negative electrode tab is not coated with a negative electrode active material layer. Taking a lithium-ion battery as an example, the material of the positive electrode current collector may be 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 manganate, etc. The material of the negative electrode current collector may be copper, and the negative electrode active material layer may include a negative electrode active material. The negative electrode active material may be carbon, silicon, etc. The material of the separator may be PP (polypropylene), PE (polyethylene), etc. In order 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] Please refer to Fig. 2. In one example of the 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 length 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] Please refer to FIG. 2. In one example of the cylindrical battery cell 100 of the present invention, a terminal mounting hole 1111 is provided in the end wall 111 of the housing 110. An electrode terminal 170 is disposed in the terminal mounting hole 1111 in a sealed and insulated manner. As long as the electrode terminal 170 is sealed and insulated from the end wall 111, the manner in which the electrode terminal 170 is disposed on the end wall 111 is not limited. 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 are applied to the present invention.

[0035] Please refer to Figs. 1 to 3. In one example of the cylindrical battery cell 100 of the present invention, the current collecting member 130 is disposed in the housing 110 and 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. As long as a stable electrical connection between the current collecting member 130 and the first tab 121 is achieved, the specific position where the current collecting member 130 and the first tab 121 are welded and the welded area between them are not limited. The cap 140 is disposed on the opening 113 side of the housing 110 and disposed 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, so that the cap 140 is sealingly connected 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 can meet 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 any connection method that meets the electrical connection requirements, such as welding connection, integral connection, rivet connection, etc. One end of the thickened portion 131 away 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 position 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 edge region of the current collector 133 as long as the position of the thick portion 131 satisfies the requirements for the welding connection strength and current distribution between the thick portion 131 and the cap 140. In this embodiment, the shape of the thick portion 131 is not particularly limited, but may be any shape, such as a disk shape, an annular shape, or a rectangular shape, as long as the shape of the thick portion 131 satisfies the requirements for the welding connection and current distribution.

[0036] When assembling a conventional cylindrical battery cell, it is usually necessary to process a roll groove on the side wall of the housing, then weld a current collecting member to the roll groove, and finally seal and fix a cap on the opening of the housing by crimping. During the crimping and sealing operation, the welded surface between the roll groove and the current collecting member is easily pulled, which will damage the welded part and affect the conductive performance of the cylindrical battery cell. At the same time, the roll groove will also occupy the radial and axial space of the housing, which will reduce the utilization rate of the space in 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 fixing 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 side wall 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 groove and crimp sealing are not included in the assembly process of the battery cell, so that the conduction between the current collecting member 130 and the housing 110 is not affected. Therefore, not only can the stability of the current carrying performance of the cylindrical battery cell 100 be improved, but also the utilization rate of the internal space of the cylindrical battery cell 100 can be improved, thereby improving the volumetric energy density of the battery cell. At the same time, by providing the thickened portion 131 on the current collecting member 130, the thickness of the current collecting member 130 at the welding position with the cap 140 is increased, 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 low process window in welding and reduction of defect rate of welding between 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 during the welding process between the current collecting member 130 and the cap 140 and transmitted to the electrode assembly 120, thereby reducing the thermal effect on the electrode assembly 120. In addition, the thickened portion 131 is in contact with a part of the area of ​​the cap 140, and the adhesion at the contact surface between them is better. In this way, the possibility of virtual solder or welding loss can be further reduced when performing welding to connect the current collecting member 130 and the cap 140, which can improve the welding quality and reduce the welding defect rate.

[0038] Please refer to FIG. 3 to FIG. 5. In one example of the cylindrical battery cell 100 of the present invention, the thick part 131 is located in the central region of the current collecting member 130. As long as the shape of the thick part 131 can meet the requirements of the mechanical connection strength and current distribution of the cap 140 and the current collecting member 130, the thick part 131 may have various shapes such as a disk shape, an annular shape, a rectangular shape, etc. By arranging the thick part 131 in the central region of the current collector 133, the welding area of ​​the cap 140 corresponding to the thick part 131 is also located in the central region of the cap 140. In this way, in the welding process, the entire welding process can be completed by only 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 thick part 131 is a cylindrical structure, and the thick part 131 and the cap 140 are arranged coaxially. With this configuration, the thick portion 131 and the cap 140 can be easily positioned in the circumferential direction during welding, and the efficiency of welding the cap 140 and the current collecting member 130 can be improved.

[0039] Please refer to FIG. 3. In one example of the 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 area with a diameter of 18 mm and a circle centered on the center of the electrode assembly 120. In order 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 set in an area with a thick tab lamination. As can be seen from the tab fabrication process, in the area with a diameter of 18 mm and a circle centered on the center of the electrode assembly 120, the number of tab laminations is small and the tab lamination thickness is thin, so that such an area is not suitable for use as the tab welding region 134. Therefore, by disposing the thickened portion 131 in this area, a configuration can be realized in which the tab welding region 134 is separated from the welded area 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 in the welding process of the current collecting member 130 can also 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 the 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. Since 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 also improved, and the connection strength becomes more reliable.

[0041] Further, please refer to Fig. 4 and Fig. 5. In one example of the cylindrical battery cell 100 of the present invention, the current collector 133 and the thick wall portion 131 may be connected by welding, instead of being integrally molded. One end of the thick wall portion 131 remote from the cap 140 is welded to the current collector 133. The method of welding is not particularly limited, and any method such as through welding or seam welding may be used as long as it can meet the requirements for stable connection between the current collector 133 and the thick wall portion 131 and current division. Since the current collector 133 and the thick wall portion 131 are connected by welding, the molding process of the current collector 133 and the thick wall portion 131 is relatively simple, and a combination of different thicknesses can be adopted, so that the processing adaptability is relatively good.

[0042] Please refer to Figs. 3 to 5. In one example of the cylindrical battery cell 100 of the present invention, the maximum thickness of the current collecting member 130 is T, and the thickness T between one end of the current collecting member 130 close to the electrode assembly 120 and one end where the thickened portion 131 is welded to the cap 140 in the thickness direction of the current collecting member 130 is preferably larger than half the thickness of the cap 140. For example, when 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, more preferably 0.60 mm to 0.65 mm, for example, 0.60 mm, 0.62 mm, 0.65 mm, etc. If the value of the thickness T is too large, the thickness T will occupy more of the internal space of the housing 110, which will affect the volumetric energy density of the battery cell. If the value of the thickness T is too small, it will be difficult to effectively reduce the probability that the current collecting member 130 will be welded, which will affect the welding quality 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 current collecting member 130 is thin, making it less susceptible to welding penetration problems. In this way, better welding quality can be obtained.

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

[0044] Please refer to FIG. 5. In another example of the cylindrical battery cell 100 of the present invention, a mounting through-hole 1331 is opened along the thickness direction of the current collector 133, and one end of the thick part 131 close to the electrode assembly 120 is inserted into the mounting through-hole 1331, so that the lower surface of the thick part 131 can be flush with the lower surface of the current collector 133. This configuration makes it easy to configure and position the thick part 131 in the current collector 133, and the thick part 131 and the current collector 133 are connected by seam welding (the welding position is indicated by an arrow in FIG. 5). By observing the welding marks, the quality of the welding connection can be intuitively and visually confirmed, so that quality problems of the welding connection can be detected in a timely manner and early intervention can be performed 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 alloy. In order to facilitate the welding connection, the material of the current collecting member 130 welded to the cap 140 can be changed in accordance with the change in the material of the cap 140. In order to ensure the strength and conductive performance of the cap 140, in one example of the 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. With such a configuration, welding between the same materials is facilitated, and the welding quality is improved. In another embodiment, only the thick portion 131 may be made of low carbon steel, and the current collector 133 may be formed of a flexible metal such as copper. With such a configuration, not only the welding between the thick portion 131 and the cap 140 is facilitated and the welding quality is ensured, but also the current collector 133 can be given a certain degree of flexibility, thereby reducing the effect of deformation stress on the tab welding area during the welding process of the cap 140.

[0046] Please refer to 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 manner in 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 adhesion, or may be clamped to the liquid injection hole 160 by interference fit. As long as the sealing requirements of the liquid injection hole 160 can be met, the liquid injection hole 160 may be sealed by sealing welding. This configuration not only allows the circumferential direction of the liquid injection hole 160 to be conveniently and accurately positioned when injecting liquid, but also solves the problem that the eccentric liquid injection of the electrode assembly 120 affects the uniformity of liquid injection. Along the axial direction of the electrode assembly 120, the projection of the liquid injection hole 160 on the end face of the current collecting member 130 covers the opening 132 or fits within the opening 132, achieving communication between the liquid injection hole 160 and the opening 132. When the electrolyte is injected from the liquid injection hole 160, the electrolyte can flow into the inside of 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 the requirements for liquid injection can be met. 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 contacting the welded area of ​​the cap 140 and the current collecting member 130 during the injection process, thereby preventing the 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. In consideration of 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 the 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, and the value may be, for example, 2 mm, 3 mm, 4 mm, or 7 mm.

[0048] Please refer to FIG. 9. In one example of the cylindrical battery cell of the present invention, an extension portion is disposed along the peripheral side wall of the liquid injection hole 160 at one end of the liquid injection hole 160 close 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, and the inner hole wall 1611 is close to the center of the liquid injection hole 160. The outer hole wall 1612 may be attached to the side wall of the opening 132, or there may be a gap between the outer hole wall 1612 and the side wall of the opening 132. In the present invention, the depth to which the extension portion extends into the opening 132 is not limited, and the depth may be greater than the height of the opening 132 or may be less than the height of the opening 132. By providing the extension 161, the height of the side wall of the liquid injection hole 160 increases, facilitating temporary sealing of the liquid injection hole 160 in the liquid injection step.

[0049] In one example of the 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, and the cover plate 150 covers the welded connection area between the cap 140 and the thickened part 131. The shape of the cover plate 150 is not particularly limited, and may be circular, rectangular, annular, etc., as long as it can cover the welded connection area. Since the nickel plating 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, and the welded mark is very likely to corrode, and the welded connection may fail. By disposing the cover plate 150 on the welded connection area, the welded connection area can be prevented from contacting the surrounding air, and the degree of corrosion of the welded mark can be reduced. In this way, the probability of failure of the welded connection between the cap 140 and the current collecting member 130 can be reduced, and the service life of the cylindrical battery cell 100 can be extended.

[0050] Please refer to Fig. 6. In one example of the cylindrical battery cell 100 of the present invention, the liquid injection hole 160 is located at 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 and at the same time protect the weld marks in the welded connection area.

[0051] Please refer to FIG. 3, FIG. 7, and FIG. 8. In one example of the 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, and the cavity bottom wall 1411 is welded to one end of the thick part 131 away from the electrode assembly 120. In one embodiment of the present invention, the relative position of the recess 141 and the cover body 144 is 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 requirement of the welded connection between the recess 141 and the thick part 131 can be met. At the same time, the area dimension of the recess 141 is not particularly limited, as long as the requirement of the welding strength between the cavity bottom wall 1411 and the thick part 131 can be met. The recess 141 is disposed on the cap 140, so that the cavity bottom wall 1411 contacts the current collecting member 130. With this configuration, a part of the area of ​​the cap 140 contacts the surface of the current collecting member 130, thereby improving the adhesion of the contact surface between the cap 140 and the current collecting member 130. In this way, the stability of the welded connection between the cap 140 and the current collecting member 130 is improved. At the same time, the recess 141 can form a certain distribution area of ​​the weld marks on the cap 140, so that the welding position error occurring during the welding process can be easily detected in a timely manner.

[0052] Please refer to Figures 3, 7 and 8. In one embodiment of the present invention, the recess 141 is a disk-shaped structure and is arranged coaxially with the cap 140. On the one hand, such a design eliminates the need to assemble the cap 140 at a certain angle in the circumferential direction, and the recess 141 can 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, a force is applied uniformly in the circumferential direction, which can reduce the stress deformation of the current collecting member 130.

[0053] Specifically, as long as the projection of the recess 141 and the projection of the thick portion 131 overlap in the thickness direction of the current collecting member 130, the welded connection between the recess 141 and the thick portion 131 can be achieved. However, preferably, please refer to FIG. 6. In one example of the cylindrical battery cell 100 of the present invention, the projection of the thick 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 thick portion 131 during the assembly process of the battery cell, the welding effect between the cap 140 and the current collecting member 130 is not affected.

[0054] Please refer to Figures 3, 7, and 8. In one example of the 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 the annular groove 142 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 both radial sides of the annular bottom wall 1421, and the first annular side wall 1422 is close 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 arranged at intervals 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 bolt connection, integral connection, welding connection, 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 an inner surface of the side wall 112 of the housing 110. On the one hand, 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, and improves the consistency of the assembly accuracy of the product. On the other hand, when the position limiting portion 1424 is laser-welded to the outside of the housing 110 where it radially abuts against the end surface of the side wall 112 of the housing 110, a weld molten pool is simultaneously attached to the position limiting 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, since the molten pool is attached to the second annular side wall 1423, it is possible to prevent the weld slag generated when welding the housing 110 from falling into the housing 110 and affecting the operating performance of the battery cell.

[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] Please refer to FIG. 9. Unlike the example of FIG. 6 in which the thickened portion 131 is provided in the central region of the current collecting member 130, the thickened portion 131 is provided in the central region of the current collecting member 130. In one example of the cylindrical battery cell 100 of the present invention, the thickened portion 131 is disposed in the outer edge 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 to achieve 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 edge region of the cap 140. When the ventilation notch 143 is provided in the cap 140, the welded region does not affect the opening of the ventilation notch 143, making it easier to discharge 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 mark in the annular groove 142, thereby reducing the probability of failure of the welded connection between the cap 140 and the current collecting member 130, and prolonging the service life of the cylindrical battery cell 100.

[0058] Please refer to Figures 8 and 9. In one example of the cylindrical battery cell 100 of the present invention, the cover body 144 of the cap 140 is machined with a ventilation notch 143. The ventilation notch 143 may be a continuous annular structure or a discontinuous structure. The ventilation notch 143 is located in a weak area of ​​the cap 140. When the air pressure in the cylindrical battery cell 100 exceeds a certain threshold, the position where the ventilation notch 143 is located will be broken, and the air pressure in the cylindrical battery cell 100 will be released from the broken part, thereby preventing heat from diffusing laterally in the cylindrical battery and causing more serious consequences. Preferably, in one embodiment of the present invention, the ventilation notch 143 has a circular structure and can be arranged coaxially with the cap 140. In this way, the force applied to the ventilation notch 143 is relatively uniform in the circumferential direction, which ensures that the ventilation notch 143 is opened more timely and accurately.

[0059] Please refer to Figures 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 be an inverted cone structure, with one end with a larger diameter facing the electrode assembly 120. The ventilation notch 143 damages the nickel plating layer on the surface of the cap 140, so that corrosion is likely to occur at the position of the ventilation notch 143, which affects the opening pressure of the ventilation notch 143. By arranging the ventilation notch 143 on one side facing the electrode assembly 120 so that the ventilation notch 143 is located in the sealed space in the housing 110, the opportunity for the ventilation notch 143 to come into contact with air can be reduced. In this way, the degree of corrosion of the ventilation notch 143 can be reduced, and the service life of the ventilation notch 143 can be improved.

[0060] In addition, the liquid injection hole in the above embodiment may be provided on the end wall 111 side of the housing 110 instead of the cap 140, and thus may also function to inject liquid into the inside of the electrode assembly 120. Please refer to FIG. 10. In one embodiment of the present invention, the electrode terminal 170 is provided with a liquid injection hole 160', and the electrolyte flows into the inside of 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 from 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, the welding slag generated when welding the cap 140 to the current collecting member 130 does not enter the inside of the battery cell through the liquid injection hole 160' and contaminate the electrolyte, and the service life of the cylindrical battery cell 100 is improved. On the other hand, when the blocking plate 180 seals the liquid injection hole 160' by welding, the welding area is far away from the second tab 122, so that the thermal effect on the second tab 122 during the welding process is small. At the same time, since the electrode terminal 170 itself has a certain thickness during welding, the electrode terminal 170 can reduce the transfer of thermal energy generated by welding to the inside of the battery cell, thereby reducing the possibility of thermal decomposition of the electrolyte. In another embodiment, the liquid injection hole may be opened in the end wall 111 of the housing 110, which can prevent the welding slag generated when the cap 140 and the current collecting member 130 are welded from entering the inside 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 a positive terminal of the cylindrical battery cell 100, and the housing 110 is negatively charged as a whole and functions as a negative terminal of the cylindrical battery cell 100. In other embodiments, the electrode terminal 170 may be negatively charged and functions as a negative electrode terminal of the cylindrical battery cell 100, and the housing 110 may be positively charged as a whole and functions as a 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 are covered with 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] Please refer to 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 to obtain electric energy for support. The operating unit 310 may be a unit component that can obtain electric energy from the battery pack 200 to perform corresponding operations, such as a blade rotation unit of a fan, a dust collection unit of a vacuum cleaner, or a wheel drive unit of an electric car. The electronic device 300 may be a vehicle, a mobile phone, a portable device, a laptop, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle may be a fuel vehicle, a gasoline vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, a long-distance vehicle, etc. The spacecraft includes an aircraft, a rocket, a space shuttle, a spaceship, etc. The electric toy includes a stationary or mobile electric toy, such as a game machine, an electric car toy, an electric ship toy, an electric plane toy, etc. 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 drivers, 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 realize the operation of the vehicle.

[0063] In the cylindrical battery cell of the present invention, the current collecting member is provided with a thickened portion, so that the thickness of the current collecting member at the welding position with the cap is increased, and the risk of virtual solder or weld penetration at the welding position during laser penetration welding is reduced. In this way, the difficulty of welding between the current collecting member and the cap can be effectively reduced, the problem of a low process window in welding can be solved, and the welding quality can be effectively improved, as well as the defect rate of welding between the cap and the current collecting member can be reduced. At the same time, the configuration of the thickened portion can effectively reduce the heat generated during the welding process between the current collecting member and the cap and transmitted to the electrode assembly, thereby reducing the thermal impact on the electrode assembly. Furthermore, since the thickened portion is in contact with a part of the area of ​​the cap, the adhesion at the contact surface between them is better. In this way, when welding to connect the current collecting member and the cap, the possibility of virtual solder or weld loss can be further reduced, which can improve the welding quality and reduce the defect rate of welding. In this way, the present invention effectively overcomes the practical problems in the prior art, and has high utility value and great utility significance. The above embodiment is merely an example of the principle and effect of the present invention, and does not limit the present invention. Anyone with ordinary skill in the art may 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 be included in 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 cells 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: Circular bottom wall 1422: First annular side wall 1423: Second annular side wall 1424: Position regulation part 143: Ventilation notch 144: Lid 150: Lid plate 160, 160': Liquid injection hole 170: Electrode terminal 180: Barrier 190: Annular cover plate 200: Battery pack 210: Case body 211: First case body 212: Second case body 300: Electronic equipment 310: Operating part

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, the electrode assembly 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, In a 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 connected to the cap by welding. Cylindrical battery cell.

2. The thick portion is disposed in a central region of the current collecting member.

2. The cylindrical battery cell according to claim 1.

3. 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 with the center of the electrode assembly as a circular center.

3. The cylindrical battery cell according to claim 2.

4. The current collector and the thick portion are integrally formed.

2. The cylindrical battery cell according to claim 1.

5. The current collector and the thick portion are connected by welding.

2. The cylindrical battery cell according to claim 1.

6. In the thickness direction of the current collecting member, a thickness between one end of the current collecting member close to the electrode assembly and one end where the thickened portion is welded to the cap is 0.3 mm to 2 mm.

6. The cylindrical battery cell according to claim 5.

7. the thickened portion is disposed on one side of the current collector away from the electrode assembly; 6. The cylindrical battery cell according to claim 5.

8. The thick portion penetrates the current collector in a thickness direction of the current collector.

6. The cylindrical battery cell according to claim 5.

9. At least one of the current collector and the thick portion is made of low carbon steel.

2. The cylindrical battery cell according to claim 1.

10. a center of the cap includes a liquid injection hole, a center of the current collecting member includes an opening corresponding to the liquid injection hole, 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; 2. The cylindrical battery cell according to claim 1.

11. The cover plate covers a welded connection area between the cap and the thickened portion.

11. The cylindrical battery cell of claim 10.

12. In a thickness direction of the cap, the cap includes a recess recessed toward the current collecting member, and the recess is welded to the thick portion.

2. The cylindrical battery cell according to claim 1.

13. In the thickness direction of the current collecting member, a projection of the thick portion covers a projection of the recess.

13. The cylindrical battery cell of claim 12.

14. At least a part of the lower surface located at the outer edge of the cap is in contact with the end surface of the side wall and welded to the cap, and an annular groove recessed toward the electrode assembly is further disposed on the outer edge of the cap in the thickness direction of the cap, and a side wall of the annular groove far from the circular center of the cap is in contact with the inner surface of the side wall and welded to the cap.

2. The cylindrical battery cell according to claim 1.

15. A bottom wall of the annular groove contacts the current collecting member.

15. The cylindrical battery cell of claim 14.

16. the thick portion is disposed in an outer peripheral region of the current collecting member, and a bottom wall of the annular groove is in contact with and welded to the thick portion; 15. The cylindrical battery cell of claim 14.

17. 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.

15. The cylindrical battery cell of claim 14.

18. The cap further includes a ventilation notch.

2. The cylindrical battery cell according to claim 1.

19. 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 an 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.

2. The cylindrical battery cell according to claim 1.

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

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