Cylindrical battery cell, battery assembly, and electronic device

Abstract

PURPOSE: To provide a cylindrical battery cell, a battery assembly, and an electronic device.SOLUTION: A cylindrical battery cell includes a housing, an electrode assembly, a current collector component, an end cap, and a cover plate. The housing includes an end wall and a side wall that surrounds the end wall. On one side of the side wall opposite to the end wall, an opening part is formed. On one side of the electrode assembly that faces the opening part, a first tab is disposed. The current collector component is welded to the first tab. The end cap is disposed on one side adjacent to the opening part, is welded to the side wall, and seals the opening part. In the thickness direction of the end cap, the end cap includes a concave part that is depressed toward the electrode assembly and the concave part is welded to the current collector component. The cover plate is disposed on the concave part and covers the concave part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to the field of battery technology, and in particular to cylindrical battery cells, battery assemblies, and electronic devices. [Background technology]

[0002] With the development of lithium battery technology, the demand for higher energy density in battery cells is increasing. Cylindrical batteries have become the mainstream battery cell type because they can achieve high energy density with a high assembly ratio. Currently, the negative terminal of a cylindrical battery cell is usually sealed by overlapping and welding the negative current collector and housing and crimp-sealing the end cap, which makes the entire manufacturing process complicated and reduces assembly efficiency. Summary of the Invention [Problem to be solved by the invention]

[0003] To simplify the assembly process of existing cylindrical battery cells and improve assembly efficiency, the process of crimp-sealing the end caps is typically replaced with a method of welding the housing and current collecting components to the end caps. However, when the end caps and current collecting components are welded using a penetration laser, the weld marks formed in the welded areas are exposed to the outer surface of the end caps, making the end caps more susceptible to oxidation in the welded areas and causing corrosion of the weld marks. This results in failure of the weld between the end caps and the current collecting components, which affects the service life of the cylindrical battery cells. [Means for solving the problem]

[0004] Taking into consideration the above-mentioned shortcomings of the prior art, the present invention provides a cylindrical battery cell, a battery assembly, and an electronic device that can solve the technical problem of a high failure rate of welding between an end cap and a current collecting part, which affects the lifespan of a cylindrical battery cell.

[0005] To achieve the above and other related objectives, the present invention provides a cylindrical battery cell including a housing, an electrode assembly, a current collecting component, an end cap, and a cover plate. The housing includes an end wall and a side wall surrounding the end wall. The side wall has an opening on one side opposite the end wall. The electrode assembly is disposed within the housing, and a first tab is disposed on one side of the electrode assembly facing the opening. The current collecting component is disposed on one side of the electrode assembly facing the opening, and is welded to the first tab. The end cap is disposed on one side adjacent to the opening and is welded to the side wall to seal the opening. In the thickness direction of the end cap, the end cap includes a recess recessed toward the cover body and the electrode assembly, and the recess is welded to the current collecting component. The cover plate is disposed above the recess and covers the recess.

[0006] In one example of the cylindrical battery cell of the present invention, the cover plate is welded to the end cap.

[0007] In one example of the cylindrical battery cell of the present invention, the current collecting part includes a thickened portion, and the thickened portion is welded to the recess.

[0008] In one example of the cylindrical battery cell of the present invention, the recess is located in the center of the end cap.

[0009] In one example of the cylindrical battery cell of the present invention, a liquid injection hole is disposed at the center of the recess, and an opening hole corresponding to the liquid injection hole is disposed at the center of the current collecting component.

[0010] In one example of the cylindrical battery cell of the present invention, the diameter of the liquid injection hole is 2 mm to 7 mm.

[0011] In one example of the cylindrical battery cell of the present invention, an extension is disposed at one end of the liquid injection hole close to the electrode assembly, and the extension extends into the open hole.

[0012] In one example of a cylindrical battery cell of the present invention, the recess includes a cavity bottom wall and a cavity side wall, the cover plate includes a main body portion and a connecting portion arranged around the main body portion, the main body portion protruding in a direction opposite the cavity bottom wall relative to the connecting portion, and the connecting portion abutting the cavity side wall.

[0013] In one example of the cylindrical battery cell of the present invention, a sinking platform is disposed at one end of the recess opposite the bottom wall of the cavity, and the main body is housed within the sinking platform.

[0014] In one example of a cylindrical battery cell of the present invention, at least a portion of the lower surface located at the outer periphery of the end cap abuts against the end face of the side wall for welding, and an annular groove recessed toward the electrode assembly is further disposed on the outer periphery of the end cap in the thickness direction of the end cap, and the side wall of the annular groove away from the center of the end cap abuts against the inner surface of the side wall for welding.

[0015] In one example of the cylindrical battery cell of the present invention, a venting mark is further disposed on the end cap.

[0016] In one example of the cylindrical battery cell of the present invention, a second tab is arranged on one side facing the end wall of the electrode assembly, 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 the liquid injection hole is arranged on the end wall or the electrode terminal.

[0017] The present invention further provides a battery assembly including the above-described cylindrical battery cell.

[0018] The present invention further provides an electronic device including the battery assembly described above. [Effects of the Invention]

[0019] In the cylindrical battery cell of the present invention, the end caps are hermetically welded to the side walls of the housing and then welded to the current collecting components. This configuration eliminates the need for a crimp seal process for the housing, thereby reducing the risk of connection failure when welding the current collecting components during the crimp seal process. It also reduces the space occupied by rolling grooves on the housing, thereby improving the utilization of the internal space of the battery cell. At the same time, the cylindrical battery cell of the present invention has recesses on the end caps. The recesses improve the adhesion of the contact surfaces between the end caps and the current collecting components, thereby stabilizing the welding between the end caps and the current collecting components and forming a fixed distribution area of ​​the weld marks on the end caps, thereby enabling timely detection of welding position errors during the welding process. Furthermore, the present invention has a cover plate on the end cap that covers the recesses. This configuration helps reduce the area of ​​the recesses exposed to air, slowing oxidation of the welded areas of the end caps and reducing corrosion of the weld marks, thereby reducing the failure rate of the welds between the end caps and the current collecting components and extending the service life of the cylindrical battery cell. [Brief explanation of the drawings]

[0020] In order to more clearly describe the embodiments of the present invention or the technical solutions of the prior art, the drawings that need to be used in the description of the embodiments or the prior 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 any creative efforts.

[0021] [Figure 1] 1 is an overall three-dimensional schematic view of one embodiment of a cylindrical battery cell of the present invention. FIG. [Figure 2]FIG. 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] FIG. 2 is a three-dimensional schematic view of an end cover of one embodiment of a cylindrical battery cell of the present invention. [Figure 5] FIG. 10 is a schematic structural diagram of a liquid injection hole drilled in the center of an end cap in one embodiment of a cylindrical battery cell of the present invention. [Figure 6] FIG. 2 is a cross-sectional view of the overall structure of an end cap in one embodiment of a cylindrical battery cell of the present invention. [Figure 7] FIG. 2 is a cross-sectional view of the overall structure of a cover plate in one embodiment of a cylindrical battery cell of the present invention. [Figure 8] FIG. 10 is a partial enlarged view of the arrangement position between the cover plate and the end cap in one embodiment of the cylindrical battery cell of the present invention. [Figure 9] FIG. 10 is a schematic structural diagram of a liquid injection hole drilled in the center of an end cap in one embodiment of a cylindrical battery cell of the present invention. [Figure 10] FIG. 2 is a schematic structural diagram of a liquid injection hole opened on an end wall side of a housing in one embodiment of a cylindrical battery cell of the present invention. [Figure 11] 1 is a schematic diagram of the overall structure of one embodiment of a battery assembly of the present invention. [Figure 12] 1 is a schematic structural diagram of a battery assembly of the present invention disposed in a vehicle; DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, the present invention will be described in detail with reference to specific examples. However, those skilled in the art will readily understand other advantages and effects of the present invention from the contents disclosed herein. The present invention can also be implemented or applied through other different specific implementations. Various modifications and changes can be made to the details in this specification based on different perspectives and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments may be combined with each other if 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 implementations and do not limit the scope of protection of the present invention. In the following examples, for test methods for which specific conditions are not specified, conventional conditions or conditions suggested by each manufacturer should generally be followed.

[0023] When an embodiment provides a numerical range, it should be understood that the two endpoints of each numerical range and any numerical 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 prior art knowledge and the description of the present invention by those skilled in the art. They can also be used with the methods described in the embodiments of the present invention. The devices and materials are similar or equivalent to any methods, devices, and materials in the prior art for implementing the present invention.

[0024] It should be noted that terms such as "upper," "lower," "left," "right," "middle," and "first" used in this specification are for the convenience of explanation and are not used to limit the scope of this specification. Regarding the feasible scope of the present invention, changes and adjustments of relative relationships should also be considered within the feasible scope of the present invention as long as there is no substantial change in the technical content.

[0025] 1 to 12 , the present invention provides a cylindrical battery cell 100, a battery assembly, and an electronic device. In the cylindrical battery cell 100, recesses 141 are provided on the end caps 140, thereby improving the stability of the weld between the end caps 140 and the current collecting members 130. At the same time, cover plates 150 are provided on the end caps 140, which cover the recesses 141 and prevent the welds between the end caps 140 and the current collecting members 130 in the recesses 141 from oxidizing and rusting. This reduces the failure rate of the weld between the end caps 140 and the current collecting members 130 and extends the service life of the cylindrical battery cell 100.

[0026] 1 to 3 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, an end cap 140, and a cover plate 150. A receiving cavity is formed within the housing 110 and is used to accommodate 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 size of the housing 110 can be determined based on the specific size of the electrode assembly 120. For example, the specific size of the housing 110 can meet 4680, 4695, 46120, and other standards for large cylindrical batteries. The housing 110 can 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 can be plated with a layer of anti-corrosion material, such as nickel.

[0027] Referring to Figure 2, Figure 2 further illustrates the structure of the housing 110. The housing 110 includes an end wall 111 and a side wall 112 surrounding the end wall 111. The end wall 111 is closed, and the opening 113 opposite the end wall 111 is open. The end wall 111 and the side wall 112 may be integrally formed and connected, or may be formed separately and then welded together.

[0028] 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 that performs the electrochemical reaction. The housing 110 can contain one or more electrode assemblies 120. The electrode assembly 120 is typically formed by rolling up or stacking a positive electrode sheet and a negative electrode sheet, with a separator typically disposed between the positive and negative electrode sheets. The positive electrode sheet includes a positive electrode current collector body and a positive electrode active material layer. The positive electrode active material layer is applied to the surface of the positive electrode current collector body. The positive electrode current collector body includes a positive electrode application area and a positive electrode tab connected to the positive electrode application area. The positive electrode application area is coated with the positive electrode active material layer, but the positive electrode tab is not coated with the positive electrode active material layer. The negative electrode sheet includes a negative electrode current collector body and a negative electrode active material layer. The negative electrode active material layer is applied to the surface of the negative electrode current collector body. The negative electrode current collector body includes a negative electrode coating area and a negative electrode tab connected to the negative electrode coating area. The negative electrode coating area is coated with a negative electrode active material layer, but the negative electrode tab is not. Taking a lithium-ion battery as an example, the positive electrode current collector body may be made of aluminum, and the positive electrode active material layer includes a positive electrode active material. The positive electrode active material may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganate. The negative electrode current collector body 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 cells, the battery cells may be covered with an insulating film. The insulating film may be synthesized from PP, PE, PET, PVC, or other polymer materials.

[0029] 2 , in one example of a cylindrical battery cell 100 of the present invention, an electrode assembly 120 is hermetically disposed within a housing 110. A first tab 121 and a second tab 122 are disposed at opposite ends of the electrode assembly 120 in the height direction, respectively, and the first tab 121 and the second tab 122 have opposite polarities. Here, the first tab 121 faces the opening 113 of the housing 110 and is a negative electrode tab. It should be noted 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.

[0030] 2 , in one example of a cylindrical battery cell 100 of the present invention, a terminal mounting hole 1111 is drilled through the end wall 111 of the housing 110. The electrode terminal 170 is disposed in the terminal mounting hole 1111 while being hermetically insulated. As long as the electrode terminal 170 is hermetically insulated from the end wall 111, the method of disposing the electrode terminal 170 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. The present invention is not further limited to this specific example.

[0031] 2 and 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 located on one side facing the opening 113 of the electrode assembly 120. The current collecting member 130 is welded to the first tab 121. The specific location 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 can be achieved between the current collecting member 130 and the first tab 121. The end cap 140 is disposed on one side adjacent to the opening 113 of the housing 110 and on one side of the current collecting member 130 away from the electrode assembly 120. The outer periphery of the end cap 140 is welded to the side wall 112 of the housing 110, so that the end cap 140 is hermetically connected to the opening 113 of the housing 110. The method for forming the welded periphery of the end cap 140 and the structure of the side wall 112 of the housing 110 is not limited, as long as it satisfies the strength requirements for the welded joint between the housing 110 and the end cap 140 and the sealing requirements for both. The end 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 end cap 140. The recess 141 includes a cavity bottom wall 1411. The cavity bottom wall 1411 is welded to one side of the current collecting element 130 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 located in the central region or peripheral region of the cover body 144, as long as it satisfies the welded joint requirements for the recess 141 and the current collecting element 130. At the same time, the size of the area of ​​the recess 141 is not specifically limited, as long as it meets the welding strength requirements between the cavity bottom wall 1411 and the current collecting piece 130. In an embodiment of the present invention, a cover plate 150 is further disposed on the end cover 140. The cover plate 150 is disposed on the recess 141 and covers it. As long as the connection strength requirements of the cover plate 150 are met, there are many options for disposing the cover plate 150 on the end cover 140, such as adhesive connection or welding.Furthermore, in this embodiment, the shape of the cover plate 150 is not limited, and for example, the shape of the cover plate 150 may be any shape, such as a disk shape, an annular shape, or a rectangular shape, as long as the cover plate 150 can cover the recess 141.

[0032] The assembly of conventional cylindrical battery cells typically requires machining rolling grooves into the sidewalls of the housing, welding current collecting components to the rolling grooves, and finally sealing and fixing end caps to the openings of the housing through a crimp seal process. During the crimp seal operation, the welded surfaces between the rolling grooves and the current collecting components are frequently pulled, which can damage the welds and affect the conductive performance of the cylindrical battery cell. At the same time, the rolling grooves occupy space in the housing in both the radial and axial directions, reducing the space utilization rate within the battery cell.

[0033] In one embodiment of the present invention, the conductive connection between the electrode assembly 120 and the housing 110 and the fixing of the end cap 140 in the opening 113 of the housing 110 are achieved by welding the outer periphery of the end cap 140 to the side wall 112 of the housing 110 and welding the recess 141 of the end cap 140 to the current collecting member 130. In this configuration, mechanical sealing processes such as rolling grooves and crimp seals are not involved in the battery cell assembly process, and therefore the conductive performance between the current collecting member 130 and the housing 110 is not affected. Therefore, not only can the stability of the conductive performance of the cylindrical battery cell 100 be improved, but the space utilization rate inside the cylindrical battery cell 100 can also be improved, thereby increasing the volumetric energy density of the battery cell. At the same time, by disposing the recess 141 on the end cap 140, the cavity bottom wall 1411 of the recess 141 abuts against the current collecting element 130, so that a portion of the end cap 140 abuts against the surface of the current collecting element 130. This improves the adhesion of the welding surfaces between the end cap 140 and the current collecting element 130 and enhances the stability of the weld between the end cap 140 and the current collecting element 130. At the same time, the recess 141 on the end cap 140 forms a fixed distribution area of ​​the weld mark, allowing for timely detection of welding position errors during the welding process. Furthermore, by disposing the cover plate 150 to cover the recess 141, this configuration helps reduce the area of ​​the recess 141 exposed to air, thereby slowing down the oxidation of the weld mark between the end cap 140 and the current collecting element 130 and reducing corrosion of the weld mark. This reduces the failure rate of the weld between the end cap 140 and the current collecting element 130 and extends the service life of the cylindrical battery cell 100.

[0034] 2 and 3 , in one example of a cylindrical battery cell 100 of the present invention, the cover plate 150 and the end cap 140 are welded together. There are many options for seam welding the cover plate 150 and the end cover 140, such as fillet welding and groove welding, as long as the strength requirements of the welded joint are met. The cover plate 150 and the end cover 140 are welded together, resulting in high joint strength. This reduces the likelihood that the cover plate 150 will slip out of or fall out of the recess 141 when the cylindrical battery cell 100 is subjected to an external force during transportation or placement, thereby ensuring the cover plate 150's protective function against the recess 141.

[0035] Referring to FIG. 3, FIG. 3 further illustrates the structure of the current collecting element 130. The current collecting element 130 includes a current collecting body 133 and a thickened portion 131. The current collecting body 133 is welded to the first tab 121 on one side facing the electrode assembly 120. In one embodiment of the present invention, one end of the thickened portion 131 in the thickness direction is conductively and fixedly connected to the current collecting body 133. The structural shape of the conductive and fixed connection is not limited as long as a stable mechanical and electrical connection can be established. The other end of the thickened portion 131 in the thickness direction is welded to the cavity bottom wall 1411 of the recess 141. The arrangement of the thickened portion 131 reduces the difficulty of welding when the recess 141 and the thickened portion 131 are welded to the outside of the housing 110 using a penetration laser, widens the welding process window, and reduces the phenomenon of welding penetration of the current collecting element 130, thereby improving welding quality. At the same time, it is possible to reduce the probability of contaminating the electrolyte due to welding slag entering the electrolyte from the welding penetration position when the current collecting part 130 is welded through, and it is also possible to reduce the risk of electrolyte leakage from the welding penetration position, thereby extending the service life of the cylindrical battery cell 100.

[0036] Specifically, the end 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 element 130 to be welded to the end cap 140 may be changed accordingly. To ensure the strength and electrical conductivity of the end cap 140, in one example of the cylindrical battery cell 100 of the present invention, the end cap 140 is made of low-carbon steel. Correspondingly, the material of the current collecting element 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 collecting body 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 end cap 140 and ensures welding quality, but also allows the current collecting body 133 to have a certain flexibility, thereby reducing the impact of deformation stress on the tab welding area during the welding process of the end cap 140.

[0037] 3 and 4 , in one example of the cylindrical battery cell 100 of the present invention, the recess 141 is disposed at the center of the end cap 140. The protrusion shape of the recess 141 on the end cap 140 may be various shapes, such as a disk shape, annular shape, or rectangular shape, as long as it meets the requirements of mechanical connection strength and current branching between the end cap 140 and the current collecting element 130. By disposing the recess 141 at the center of the end cap 140, welding can be completed in the entire area of ​​the recess 141 by simply moving the welding head back and forth in the central area during the welding process, thereby obtaining a better welding path and improving the welding efficiency between the end cap 140 and the current collecting element 130.

[0038] 4 to 6 , in one example of a cylindrical battery cell 100 of the present invention, a liquid injection hole 160 is disposed in the central region of the end cap 140, and a corresponding opening hole 132 is disposed in the central region of the current collecting member 130. The liquid injection hole 160 and the opening hole 132 are disposed concentrically or substantially concentrically with the central hole 123 of the electrode assembly 120. This configuration not only allows for convenient and accurate circumferential positioning of the liquid injection hole 160 when injecting liquid, but also solves the problem of eccentric liquid injection within the electrode assembly 120 affecting 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 or falls into the opening hole 132, thereby achieving communication between the liquid injection hole 160 and the opening hole 132. When the electrolyte is injected through the liquid injection hole 160, the liquid enters the central hole 123 through the opening hole 132 and permeates the electrode assembly 120. As long as the liquid injection requirements are met, the liquid injection hole 160 and the opening hole 132 can be formed in various shapes, such as a circle, a rectangle, or a strip. Referring to FIG. 5 , in one embodiment of the present invention, the projection of the liquid injection hole 160 on the end face of the current collecting element 130 falls completely into the opening hole 132. This configuration prevents the electrolyte from contacting the recess 141 and the welding area of ​​the current collecting element 130 during the injection process, thereby preventing welding slag from flowing from the welding area into the electrode assembly 120 and affecting the injection effect of the electrode assembly 120.

[0039] The diameter of the liquid injection hole 160 may be from 1 mm to 14 mm. Taking into consideration the operation of the liquid injection process, the diameter of the liquid injection hole 160 is preferably 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 from 2 mm to 7 mm, such as 2 mm, 3 mm, 4 mm, or 7 mm.

[0040] Referring to FIG. 9 , in one example of a cylindrical battery cell 100 of the present invention, an extension portion 161 is disposed along the height direction of the liquid injection hole 160 at one end of the liquid injection hole 160 closer to the electrode assembly 120, along the circumferential sidewall of the liquid injection hole 160. The extension portion 161 extends downward into the opening hole 132. The extension portion 161 includes 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 hole 132, or there may be a gap between the outer hole wall 1612 and the sidewall of the opening hole 132. In the present invention, the depth to which the extension portion 161 extends into the opening hole 132 is not limited, and the depth may be greater than the height of the opening hole 132, or may be less than or equal to the height of the opening hole 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 during the liquid injection process.

[0041] 6 to 8, which further illustrate the structure of the recess 141 and the cover plate 150, as well as the arrangement and cooperative relationship between them. The recess 141 includes a cavity bottom wall 1411 and a cavity side wall 1412 connected to the cavity bottom wall 1411. The cover plate 150 includes a main body 151 and a connecting portion 152 connected to the edge of the main body 151. The main body 151 and the connecting portion 152 may be integrally connected, but the present invention is not limited thereto. As shown in the figures, the main body 151 protrudes toward the connecting portion 152 in a direction opposite to the cavity bottom wall 1411, and the connecting portion 152 abuts against the cavity side wall 1412. The connection between the connecting portion 152 and the cavity side wall 1412 may be established via an interference fit or any connection method that can meet the connection strength requirements, such as welding. With this configuration, an avoidance cavity 1414 is formed between the main body 151 and the cavity bottom wall 1411, so that welding marks distributed on the cavity bottom wall 1411 can be accommodated in the avoidance cavity 1414, thereby reducing interference between the welding marks and the upper cover plate 150 and preventing the flatness for positioning the cover plate 150 from being affected. It should be noted that in another embodiment of the present invention, referring to FIG. 5 , when a liquid injection hole 160 is opened in the recess 141, in this situation, the connecting portion 152 of the cover plate 150 and the cavity side wall 1412 need to be sealed. For example, in one embodiment of the present invention, welding can be used to connect the connecting portion 152 and the cavity side wall 1412. This improves the reliability of the seal and makes the connection strength strong enough to withstand external impacts.

[0042] 8 , to facilitate positioning and placement of the cover plate 150 in the recess 141, in another embodiment of the present invention, the cavity sidewall 1412 and the circumferential sidewall of the connecting portion 152 of the cover plate 150 can have matching shapes to facilitate guiding and placement. Such an arrangement facilitates quick and accurate positioning and placement of the cover plate 150 in the recess 141, thereby improving the placement efficiency of the cover plate 150 on the end cap 140.

[0043] 4 to 8 , in one example of the cylindrical battery cell 100 of the present invention, the recess 141 further includes a cavity recessed pedestal 1413 connected to the cavity side wall 1412. The cavity recessed pedestal 1413 is located at one end of the cavity side wall 1412, away from the cavity bottom wall 1411. The cavity recessed pedestal 1413 is lower than the upper surface of the end cap 140, so that after the cover plate 150 is placed in the recess 141, the upper surface of the main body 151 of the cover plate 150 is not higher than the upper surface of the end cap 140. With this arrangement, an avoidance groove 1415 is formed between the cavity recessed pedestal 1413 and the upper surface of the cover plate 150. When the connection portion 152 of the cover plate 150 is welded to the cavity side wall 1412, a molten weld pool adheres to the avoidance groove 1415. On the one hand, the flow of the molten pool is set within a certain range, thereby improving the welding quality between the connection portion 152 and the cavity side wall 1412, and on the other hand, it is possible to prevent the welding scar from protruding from the upper surface of the end cap 140, thereby reducing the space utilization rate at the upper surface of the end cap 140. Furthermore, the depth of the cavity recessed base 1413 can be adjusted so that the upper surface of the main body 151 of the cover plate 150 is lower than the upper surface of the end cap 140, thereby further reducing the impact on the space utilization rate at the upper surface of the end cap 140.

[0044] 3 and 6 , in one example of a cylindrical battery cell 100 of the present invention, the cover body 144 includes an annular groove 142. The annular groove 142 is disposed on the outer periphery of the end cap 140 and is recessed toward the electrode assembly 120 in the thickness direction of the end cap 140. The annular groove 142 and the cover body 144 are integrally formed by stamping. As shown in the figures, 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 sides of the annular bottom wall 1421. A position limiting portion 1424 is disposed at one end of the second annular side wall 1423 away from the annular bottom wall 1421. The second annular side wall 1423 is away from the center of the end cap 140, and the position limiting portion 1424 extends toward one side away from the center of the end cap 140. The position limiting portion 1424 may be an integral annular structure connected to the outer circumferential surface of the second annular side wall 1423, or may be a plurality of block-like structures spaced apart from one another on the outer circumferential surface of the second annular side wall 1423. The method for connecting the position limiting portion 1424 and the second annular side wall 1423 is not limited, and the connection may be achieved via bolts, integral connection, welding, or the like. One end surface of the position limiting portion 1424 facing the annular bottom wall 1421 abuts and welds to the end surface of the side wall 112 of the housing 110, and the outer surface of the second annular side wall 1423 abuts and welds to the inner surface of the side wall 112 of the housing 110. The position limiting portion 1424 and the second annular side wall 1423 improve the positioning accuracy of the end cap 140 in the axial and radial directions of the housing 110, thereby 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 limiting portion 1424 abuts against the end surface of the side wall 112 of the housing 110 in the radial direction, a molten pool simultaneously adheres to the position limiting portion 1424 and the second annular side wall 1423, thereby increasing the welded joint area between the end cap 140 and the housing 110 and improving the welded joint 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 the housing 110 is welded through from falling into the housing 110 and affecting the operational performance of the battery cells.

[0045] 3 and 6 , in one example of a cylindrical battery cell 100 of the present invention, a venting mark 143 is machined on the cover body 144 of the end cap 140. The venting mark 143 may have a continuous annular structure or a discontinuous structure. The venting mark 143 is located in a fragile area of ​​the end cap 140. When the air pressure inside the cylindrical battery cell 100 exceeds a certain threshold, the area where the venting mark 143 is located will rupture, and the air pressure inside the cylindrical battery cell 100 will be released from the rupture, thereby preventing heat from spreading laterally within the cylindrical battery and causing more drastic consequences.

[0046] 3 and 6, the venting mark 143 is located on one side of the end cap 140 facing the electrode assembly 120. The venting mark 143 is perpendicular to the surface of the end cap 140 in the depth direction. The cross section of the venting mark 143 may be an oblique cone, with one end with a larger diameter facing the electrode assembly 120. Because the nickel plating layer on the surface of the end cap 140 is damaged by the venting mark 143, the location of the venting mark 143 is highly susceptible to corrosion, which affects the opening pressure of the venting mark 143. By locating the venting mark 143 on the side facing the electrode assembly 120, the venting mark 143 is located within the sealed space of the housing 110, reducing contact between the venting mark 143 and air and reducing the degree of corrosion of the venting mark 143. This increases the service life of the venting mark 143.

[0047] It should be noted that in the above-described embodiment, the liquid injection hole may be located on the end wall 111 of the housing 110 instead of on the end cap 140, thereby fulfilling the function of injecting liquid into the electrode assembly 120. Referring to FIG. 10 , in one embodiment of the present invention, a liquid injection hole 160′ is located on the electrode terminal 170, and the electrolyte enters the electrode assembly 120 through the liquid injection hole 160′. A blocking plate 180 is also located on the electrode terminal 170. The blocking plate 180 seals the liquid injection hole 160′ and prevents the electrolyte from overflowing through the liquid injection hole 160′. The liquid injection hole 160′ is located on the electrode terminal 170. Meanwhile, the liquid injection hole 160′ and the end cap 140 are located at both ends of the housing 110, respectively. Therefore, welding slag generated when the end cap 140 and the current collecting member 130 are welded together will not enter the battery cell through the liquid injection hole 160′ and contaminate the electrolyte, thereby improving the service life of the cylindrical battery cell 100. On the other hand, when the shielding plate 180 is welded to seal the liquid injection hole 160′, the welding area is far from the second tab 122, so the second tab 122 is less susceptible to thermal shock during the welding process. At the same time, because the electrode terminal 170 itself has a certain thickness during welding, the electrode terminal 170 can mitigate the transfer of heat energy generated by welding to the inside of the battery cell, thereby reducing the likelihood of thermal decomposition of the electrolyte. In another embodiment, a liquid injection hole may be drilled on the end wall 111 of the housing 110, thereby preventing welding slag generated when the end cap 140 and the current collecting member 130 are welded together from entering the battery cell through the liquid injection hole and contaminating the electrolyte. It should be noted that 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, while the housing 110 is negatively charged overall 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 overall and functions as the positive terminal of the cylindrical battery cell 100.

[0048] 11 , in one embodiment of a battery assembly 200 of the present invention, the battery assembly 200 includes a case 210 and at least one cylindrical battery cell 100. The case 210 includes a first case portion 211 and a second case portion 212. The first case portion 211 and the second case portion 212 cover each other to form an accommodating space. A plurality of cylindrical battery cells 100 are accommodated in the accommodating space. The plurality of cylindrical battery cells 100 can be connected in series and / or in parallel. The battery assembly 200 may be, for example, a battery module, a battery pack, etc.

[0049] Referring to FIG. 12 , in one example of an electronic device 300 of the present invention, the electronic device 300 includes a working unit 310 and a battery assembly 200. The working unit 310 is electrically connected to the battery assembly 200 and obtains electrical energy for support. The working unit 310 may be a unit component that obtains electrical energy from the battery assembly 200 and performs 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 vehicle. The electronic device 300 may also be a vehicle, a mobile phone, a portable device, a laptop, a boat, a spacecraft, an electric toy, a power tool, or the like. The vehicle may be a fuel-powered vehicle, a gas-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. The spacecraft may include an aircraft, a rocket, a space shuttle, a spaceship, or the like. The electric toys may be stationary or mobile electric toys, such as a game console, an electric toy car, an electric toy ship, an electric toy airplane, or the like. 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 electric devices. In one embodiment of the electronic device 300 of the present invention, the electronic device 300 is a vehicle, the working unit 310 is a vehicle body, and the battery assembly 200 is fixedly disposed in the vehicle body to provide driving power to the vehicle and operate the vehicle.

[0050] In the cylindrical battery cell of the present invention, by disposing a recess on the end cap, the bottom wall of the recess's cavity abuts the current collecting component, allowing a portion of the end cap to abut the surface of the current collecting component, thereby enhancing the adhesion of the contact surface between the end cap and the current collecting component and improving the stability of the weld between the end cap and the current collecting component. At the same time, the recess on the end cap forms a fixed distribution area of ​​the weld marks, allowing for timely detection of welding position errors during the welding process. Furthermore, by disposing a cover plate to cover the recess, this configuration helps reduce the area of ​​the recess exposed to air, thereby slowing down oxidation in the weld area of ​​the end cap and corrosion of the weld marks. This reduces the probability of welding connection failure between the end cap and the current collecting component and extends the service life of the cylindrical battery cell. In this way, the present invention effectively overcomes several practical problems in the prior art and has high utility value and practical significance. The above-described embodiments are merely examples intended to illustrate the principles and effects of the present invention and are not intended to limit the present invention. Those skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, any equivalent modifications or variations made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the present invention. [Industrial Applicability]

[0051] The cylindrical battery cell, battery assembly, and electronic device of the present invention can be applied in the field of battery technology. [Explanation of symbols]

[0052] 100 cylindrical battery cells 110 Housing 111 End Wall 1111 Terminal mounting hole 112 Side wall 113 Opening 120 Electrode Assembly 121 Tab 1 122 Second Tab 123 Center hole 130 Current collector parts 131 Thick wall part 132 Opening hole 133 Current collector body 140 End Cap 141 recess 1411 Cavity bottom wall 1412 Cavity sidewall 1413 Cavity recessed base 1414 Avoidance Cavity 1415 Avoidance Groove 142 Annular groove 1421 Circular bottom wall 1422 First annular side wall 1423 Second annular side wall 1424 Position Restriction Unit 143 Venting Mark 144 Cover body 150 cover plate 151 Main body 152 Connection 160 / 160' liquid injection hole 161 Stretching section 1611 Inner hole wall 1612 Outer hole wall 170 Electrode terminal 180 Barrier 200 Battery Assembly 210 Box body 211 First box part 212 Second box part 300 Electronic Devices 310 Working Unit

Claims

1. a housing including an end wall and a side wall surrounding the end wall, the side wall having an opening formed on an opposite side to the end wall; an electrode assembly disposed within the housing and having a first tab disposed on one side facing the opening; a current collecting part disposed on one side of the electrode assembly facing the opening and welded to the first tab; an end cap disposed on one side adjacent to the opening, welded to the side wall to seal the opening, and including a recess recessed in a thickness direction toward the cover body and the electrode assembly, the recess being welded to the current collecting piece; a cover plate disposed above the recess and covering the recess; Including, A cylindrical battery cell, wherein the cover plate is welded to the end cap.

2. The cylindrical battery cell according to claim 1 , wherein the current collecting part includes a thickened portion, and the thickened portion is welded to the recess.

3. The cylindrical battery cell according to claim 1 , wherein the recess is disposed at the center of the end cap.

4. a liquid injection hole is disposed at the center of the recess; The cylindrical battery cell according to claim 3 , wherein an opening hole corresponding to the liquid injection hole is disposed at the center of the current collecting part.

5. 5. The cylindrical battery cell according to claim 4, wherein the diameter of the liquid injection hole is 2 mm to 7 mm.

6. The cylindrical battery cell according to claim 4 , wherein an extension portion is disposed at one end of the liquid injection hole close to the electrode assembly, and the extension portion extends into the opening hole.

7. 2. The cylindrical battery cell according to claim 1, wherein the recess includes a cavity bottom wall and a cavity side wall connected to the cavity bottom wall, the cover plate includes a main body portion and a connecting portion arranged around the main body portion, the main body portion protruding in a direction opposite to the cavity bottom wall relative to the connecting portion, and the connecting portion abutting against the cavity side wall.

8. 8. The cylindrical battery cell according to claim 7, wherein the recess further includes a cavity recessed pedestal connected to the cavity sidewall, and the cavity recessed pedestal is lower than an upper surface of the end cap, such that an upper surface of the body portion of the cover plate is not higher than an upper surface of the end cap.

9. 2. The cylindrical battery cell according to claim 1, wherein at least a portion of a lower surface located at an outer periphery of the end cap abuts against an end surface of the side wall for welding; an annular groove recessed toward one side adjacent to the electrode assembly is further disposed on the outer periphery of the end cap in the thickness direction of the end cap; and a side wall of the annular groove away from the center of the end cap abuts against an inner surface of the side wall for welding.

10. The cylindrical battery cell according to claim 1 , wherein venting marks are further disposed on the end caps.

11. 2. The cylindrical battery cell according to claim 1, wherein a second tab is disposed on one side of the electrode assembly facing the end wall, the cylindrical battery cell further includes an electrode terminal configured to protrude from an outer surface of the end wall, the electrode terminal being electrically connected to the second tab, and a liquid injection hole is disposed on the end wall or the electrode terminal.

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

13. An electronic device comprising the battery assembly of claim 12.

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