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 requirements for the energy density of battery cells are increasing. Cylindrical batteries can achieve high energy density with a high assembly ratio, so cylindrical batteries have become the mainstream of battery cells. Currently, the sealing of the negative terminal of a cylindrical battery cell is usually performed by overlapping and welding the negative current collector and the housing, and crimp-sealing the end cap, which makes the entire manufacturing process complicated and the assembly efficiency poor. Summary of the Invention [Problem to be solved by the invention]

[0003] In order to simplify the assembly process of existing cylindrical battery cells and improve assembly efficiency, the process of crimp sealing the end cap is usually replaced by a method of welding the housing and the current collecting parts to the end cap. However, when the end cap and the current collecting parts are welded by a penetration laser, the weld marks formed in the welded area are exposed to the outer surface of the end cap, which makes the end cap prone to oxidation in the welded area and causes corrosion of the weld marks. Therefore, the weld between the end cap and the current collecting parts fails, which affects the service life of the cylindrical battery cell. [Means for solving the problem]

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

[0005] 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 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 formed on one side opposite the end wall. The electrode assembly is disposed within the housing, and a first tab is disposed on one side facing the opening of the electrode assembly. The current collecting component is disposed on one side facing the opening of the electrode assembly, and the current collecting component 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 a 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 a 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, the 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 part.

[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 periphery of 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 a 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 received within the sinking platform.

[0014] In one example of the cylindrical battery cell of the present invention, at least a part of the lower surface located at the outer periphery of the end cap is welded to the end face of the side wall, and an annular groove recessed toward the electrode assembly side 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 far from the center of the end cap is welded to the inner surface of the side wall.

[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 disposed 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 disposed on the end wall or the electrode terminal.

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

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

[0019] In the cylindrical battery cell of the present invention, the end cap is hermetically welded to the side wall of the housing, and the end cap is welded to the current collecting part. This configuration can omit the crimp seal process of the housing, so that the risk of connection failure when welding the current collecting part during the crimp seal process can be reduced, and the space occupied by the rolling groove on the housing can be reduced, so that the utilization rate of the internal space of the battery cell can be improved. At the same time, the cylindrical battery cell of the present invention arranges a recess on the end cap. The recess can improve the adhesion of the contact surface between the end cap and the current collecting part, so that not only the welding between the end cap and the current collecting part is stable, but also a fixed distribution area of ​​the welding mark is formed on the end cap, so that the welding position error during the welding process can be detected in a timely manner. In addition, the present invention arranges a cover plate on the end cap, and the cover plate covers the recess. This configuration helps to reduce the area of ​​the recess exposed to air, so that the oxidation of the welding area of ​​the end cap is slowed down and the corrosion of the welding mark is reduced, thereby reducing the failure rate of the welding between the end cap and the current collecting part, and the service life of the cylindrical battery cell is extended. [Brief description 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 creative efforts.

[0021] [Figure 1] FIG. 1 is an overall three-dimensional schematic diagram of one embodiment of a cylindrical battery cell of the present invention. [Diagram 2]FIG. 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] FIG. 2 is a three-dimensional schematic view of an end cover of one embodiment of a cylindrical battery cell of the present invention. [Diagram 5] FIG. 2 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. 2 is a partial enlarged view of the placement location between the cover plate and the end cap in one embodiment of a cylindrical battery cell of the present invention. [Figure 9] FIG. 2 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] FIG. 1 is a schematic diagram of the overall structure of one embodiment of a battery assembly of the present invention. [Figure 12] FIG. 2 is a schematic structural diagram of a battery assembly of the present invention disposed in a vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, the embodiment of the present invention will be described through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. In addition, the present invention can also be implemented or applied through other different specific implementation methods. Each detail in this specification can be variously modified or changed based on different perspectives and applications without departing from the spirit of the present invention. It should be noted that, if there is no contradiction between the embodiments, the following embodiments and features in the embodiments may be combined with each other. It should also be understood that the terms used in the embodiments of the present invention are for describing specific implementation methods and do not limit the protection scope of the present invention. In the following examples, for test methods for which specific conditions are not specified, the conventional conditions or the conditions suggested by each manufacturer shall usually be followed.

[0023] When an embodiment provides a numerical range, it should be understood that the two end points of each numerical range and any numerical value between the two end points 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 method, device, and material in the prior art for carrying out the present invention.

[0024] It should be noted that the terms "upper", "lower", "left", "right", "middle", "first" and the like used in this specification are for the convenience of explanation and are not used to limit this specification. As for the scope of the present invention, the change or adjustment of the relative relationship should be considered as the 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, a recess 141 is provided on the end cap 140, so that the stability of the welding between the end cap 140 and the current collecting part 130 can be improved. At the same time, the cover plate 150 is provided on the end cap 140, so that the cover plate 150 covers the recess 141, and the welding mark between the end cap 140 and the current collecting part 130 in the recess 141 can be prevented from being oxidized and rusted, thereby reducing the failure rate of the welding between the end cap 140 and the current collecting part 130, and prolonging the service life of the cylindrical battery cell 100.

[0026] 1-3 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 in the housing 110 and is used to receive 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 size of the housing 110 may be determined based on the specific size of the electrode assembly 120. For example, the specific size of the housing 110 may meet 4680, 4695, 46120, and other standards for large cylindrical batteries. The housing 110 may be made of various materials, such as copper, iron, aluminum, steel, and aluminum alloys. To prevent the housing 110 from rusting after long-term use, the surface of the housing 110 may be plated with a layer of anti-rust 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-ended and the opening 113 opposite the end wall 111 is open-ended. 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 in the housing 110. The electrode assembly 120 is a component in the battery cell that performs the electrochemical reaction. The housing 110 can include one or more electrode assemblies 120. The electrode assembly 120 is mainly formed by rolling up 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 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 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, 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 coated with a negative electrode active material layer. Taking a lithium-ion battery as an example, the material of the positive electrode current collector body may be 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, etc. The material of the negative electrode current collector body 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) or 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 can be synthesized from PP, PE, PET, PVC, or other polymer materials.

[0029] 2, in one example of the cylindrical battery cell 100 of the present invention, the electrode assembly 120 is hermetically disposed in the housing 110. The first tab 121 and the second tab 122 are disposed at both ends in the height direction of the electrode assembly 120, respectively, and the first tab 121 and the second tab 122 have opposite polarities to each other. Here, the first tab 121 faces the opening 113 of the housing 110, and the first tab 121 is a negative tab. It should be mentioned that in other embodiments, the first tab 121 may be a positive tab, and the second tab 122 may be a negative tab.

[0030] Further referring to FIG. 2, in one example of the cylindrical battery cell 100 of the present invention, a terminal mounting hole 1111 is opened through the end wall 111 of the housing 110. The electrode terminal 170 is disposed in the terminal mounting hole 1111 in a hermetically insulated state. 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 part 130. The present invention is not further specifically limited.

[0031] 2 and 3, in one example of the cylindrical battery cell 100 of the present invention, the current collecting part 130 is disposed in the housing 110 and is located on one side facing the opening 113 of the electrode assembly 120. The current collecting part 130 is welded to the first tab 121. As long as a stable electrical connection can be achieved between the current collecting part 130 and the first tab 121, the specific position and the weld area of ​​the current collecting part 130 and the first tab 121 are not limited. The end cap 140 is disposed on one side adjacent to the opening 113 of the housing 110 and is located on one side of the current collecting part 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 connected to the opening 113 of the housing 110 in a sealed state. As long as the strength requirements of the welded joint between the housing 110 and the end cap 140 and the sealing requirements of both are met, the method of forming the welded joint outer periphery of the end cap 140 and the structure of the side wall 112 of the housing 110 is not limited. The end cap 140 includes a cover body 144 and a recess 141. In the thickness direction of the end cap 140, the recess 141 is recessed toward the electrode assembly 120 side. The recess 141 includes a cavity bottom wall 1411. The cavity bottom wall 1411 is welded to one side of the current collecting part 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 specifically limited. For example, the recess 141 may be disposed in the central region or peripheral region of the cover body 144 as long as the welded joint requirements of the recess 141 and the current collecting part 130 are met. 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 part 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 the recess 141. As long as it meets the connection strength requirements of the cover plate 150, there are many options for the method of disposing the cover plate 150 on the end cover 140, such as adhesive connection or welding joint.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 rectangle, as long as the cover plate 150 can cover the recess 141.

[0032] When assembling a conventional cylindrical battery cell, it is usually necessary to machine a rolling groove on the side wall of the housing, then weld and join the current collecting parts to the rolling groove, and finally seal and fix the end cap to the opening of the housing through a crimp seal process. During the crimp seal operation, the welding surface between the rolling groove and the current collecting parts is frequently pulled, which damages the welded part and affects the conductive performance of the cylindrical battery cell. At the same time, the rolling groove occupies the space of the housing in the radial and axial directions, which reduces the space utilization rate inside 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 at 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 part 130. In this configuration, since a mechanical sealing process such as rolling groove or crimp seal is not involved in the assembly process of the battery cell, the conductive performance between the current collecting part 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 also the space utilization rate inside the cylindrical battery cell 100 can 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 component 130, so that a part of the area of ​​the end cap 140 abuts against the surface of the current collecting component 130, thereby improving the adhesion of the welding surface between the end cap 140 and the current collecting component 130 and enhancing the stability of the welding between the end cap 140 and the current collecting component 130. At the same time, the recess 141 on the end cap 140 forms a fixed distribution area of ​​the welding mark, so that the welding position error during the welding process can be detected in a timely manner. In addition, by disposing the cover plate 150 to cover the recess 141, such a configuration helps to reduce the area of ​​the recess 141 exposed to the air, so that the oxidation of the welding mark between the end cap 140 and the current collecting component 130 is slowed down and the corrosion of the welding mark is reduced. Thereby, the failure rate of the welding between the end cap 140 and the current collecting component 130 is reduced, and the service life of the cylindrical battery cell 100 is extended.

[0034] 2 and 3, in one example of the cylindrical battery cell 100 of the present invention, the cover plate 150 and the end cap 140 are welded together. As long as the strength requirements of the welded joint are met, there are many options for the method of seam welding the cover plate 150 and the end cover 140, such as fillet welding, groove welding, etc. The cover plate 150 and the end cover 140 are welded together, and the joint strength is high. When the cylindrical battery cell 100 is impacted by an external force during transportation or placement, the probability that the cover plate 150 will slip or fall out of the recess 141 can be reduced, and the protective function of the cover plate 150 against the recess 141 can be ensured.

[0035] Referring to FIG. 3, FIG. 3 further illustrates the structure of the current collecting part 130. The current collecting part 130 includes a current collecting body 133 and a thick part 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 thick part 131 in the thickness direction is conductively fixedly connected to the current collecting body 133, and the structural shape of the conductively fixed connection is not limited as long as a stable mechanical connection relationship and an electrical connection relationship can be established. The other end of the thick part 131 in the thickness direction is welded to the cavity bottom wall 1411 of the recess 141. By disposing the thick part 131, when the recess 141 and the thick part 131 are welded by a penetration laser outside the housing 110, the difficulty of welding can be reduced, the welding process window can be enlarged, and the phenomenon of welding penetration of the current collecting part 130 can be reduced, so that the welding quality can be improved. At the same time, it is possible to reduce the probability of the electrolyte being contaminated by welding slag entering the electrolyte from the welding penetration position when the current collecting part 130 is welded through, and also to reduce the risk of the electrolyte leaking 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 alloy. In order to facilitate welding joint, the material of the current collecting part 130 to be welded with the end cap 140 may be changed correspondingly with the change in the material of the end cap 140. In order to ensure the strength and conductive performance 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 part 130 is also made of low carbon steel. This configuration allows welding between the same materials to be easily performed and improves the welding quality. In another embodiment, only the thickened part 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 thickened part 131 and the end cap 140 and ensures the welding quality, but also allows the current collecting body 133 to have a certain flexibility, thereby reducing the effect 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. As long as it meets the requirements of mechanical connection strength and current branching between the end cap 140 and the current collecting part 130, the shape of the protrusion of the recess 141 on the end cap 140 may be various shapes, such as disk-shaped, annular, or rectangular. By disposing the recess 141 at the center of the end cap 140, during the welding process, the welding in the entire area of ​​the recess 141 can be completed by only moving the welding head back and forth in the central area, so that a better welding path can be obtained and the welding efficiency between the end cap 140 and the current collecting part 130 can be improved.

[0038] 4-6, in one example of the cylindrical battery cell 100 of the present invention, a liquid injection hole 160 is arranged in the central region of the end cap 140, and an opening hole 132 is correspondingly arranged in the central region of the current collecting part 130. The liquid injection hole 160 and the opening hole 132 are arranged concentrically or substantially concentrically with the central hole 123 of the electrode assembly 120. 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 eccentric liquid injection in 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 part 130 covers the opening hole 132 or falls into the opening hole 132 to realize the communication between the liquid injection hole 160 and the opening hole 132. When the electrolyte is injected from 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 shape. 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 part 130 falls completely into the opening hole 132. This configuration can prevent the electrolyte from contacting the recess 141 and the welding area of ​​the current collecting part 130 during the injection process, thereby preventing the welding slag from flowing from the welding area into the inside of 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 the cylindrical battery cell 100 of the present invention, an extension portion 161 is disposed along the vertical direction of the liquid injection hole 160 at one end of the liquid injection hole 160 close to the electrode assembly 120, along the circumferential side wall 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, 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 hole 132, or there may be a gap between the outer hole wall 1612 and the side wall 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 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 is increased, making it easier to temporarily seal the liquid injection hole 160 during the liquid injection process.

[0041] 6 to 8, which further explain the structure of the recess 141 and the cover plate 150, and the arrangement and cooperation 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 part 152 connected to the edge of the main body 151. The main body 151 and the connecting part 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 part 152 in a direction opposite to the cavity bottom wall 1411, and the connecting part 152 abuts against the cavity side wall 1412. The connection between the connecting part 152 and the cavity side wall 1412 may be established via an interference fit, or may be established via any connecting method that can meet the requirements of connection strength, 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 the welding marks distributed on the cavity bottom wall 1411 can be accommodated in the avoidance cavity 1414, thereby reducing the interference between the welding marks and the upper cover plate 150, and preventing the flatness for arranging the cover plate 150 from being affected. It should be explained that in another embodiment of the present invention, referring to FIG. 5, when the liquid injection hole 160 is opened in the recess 141, in this situation, the connection part 152 of the cover plate 150 and the cavity side wall 1412 need to be sealed, so for example, in one embodiment of the present invention, welding can be adopted to connect the connection part 152 and the cavity side wall 1412. This improves the reliability of sealing, and the connection strength is large enough to withstand external impact.

[0042] 8, to facilitate positioning and alignment 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 alignment. Such an arrangement facilitates quick and accurate positioning and alignment of the cover plate 150 in the recess 141, thereby improving the efficiency of alignment 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 body portion 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 in a certain range, which can improve the welding quality between the connection part 152 and the cavity side wall 1412, and on the other hand, it can prevent the welding mark from protruding from the upper surface of the end cap 140, which reduces the space utilization rate of the upper surface of the end cap 140. In addition, the depth of the cavity recessed platform 1413 can be adjusted, so that the upper surface of the body part 151 of the cover plate 150 is further lower than the upper surface of the end cap 140, which can further reduce the impact on the space utilization rate of the upper surface of the end cap 140.

[0044] 3 and 6, in one example of the 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 through 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, and 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 each other on the outer circumferential surface of the second annular side wall 1423. The method of connecting the position limiting portion 1424 and the second annular side wall 1423 is not limited, and the connection may be made via a bolt, an integral connection, a welded joint, or the like. One end surface of the position limiting portion 1424 facing the annular bottom wall 1421 abuts against an end surface of the side wall 112 of the housing 110 for welding, and the outer surface of the second annular side wall 1423 abuts against an inner surface of the side wall 112 of the housing 110 for welding. By arranging the position limiting portion 1424 and the second annular side wall 1423, on the one hand, the positioning accuracy of the end cap 140 in the axial and radial directions of the housing 110 is improved, and the consistency of the product assembly accuracy is improved. 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, the molten pool is simultaneously attached to the position limiting portion 1424 and the second annular side wall 1423, thereby increasing the welding joint area between the end cap 140 and the housing 110 and improving the welding joint strength and sealing performance. At the same time, since the molten pool is attached to the second annular side wall 1423, the welding slag generated when the housing 110 is welded through can be prevented from falling into the inside of the housing 110 and affecting the operating performance of the battery cell.

[0045] 3 and 6, in one example of the 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 be 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 place where the venting mark 143 is located will burst, and the air pressure inside the cylindrical battery cell 100 will be released from the burst, thereby preventing the heat from spreading laterally in the cylindrical battery and causing more drastic results.

[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 inverted cone, with one end of the large diameter facing the electrode assembly 120. The nickel plating layer on the surface of the end cap 140 is damaged by the venting mark 143, so the location where the venting mark 143 is located is very prone to corrosion, which affects the opening pressure of the venting mark 143. By arranging the venting mark 143 on one side facing the electrode assembly 120, the venting mark 143 is located in the sealed space of the housing 110, so the contact between the venting mark 143 and the air is reduced, and the degree of corrosion of the venting mark 143 is reduced. Therefore, the service life of the venting mark 143 can be increased.

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

[0048] 11, in one embodiment of the battery assembly 200 of the present invention, the battery assembly 200 includes a box 210 and at least one cylindrical battery cell 100. The box 210 includes a first box portion 211 and a second box portion 212. The first box portion 211 and the second box portion 212 cover each other to form a storage space. A plurality of cylindrical battery cells 100 are stored in the storage 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 the 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 to obtain electric energy for support. The working unit 310 may be a unit component that can obtain electric energy from the battery assembly 200 to perform corresponding work, such as a blade rotation unit of a fan, a dust collection working unit of a vacuum cleaner, a wheel drive unit of an electric vehicle, etc. The electronic device 300 may be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, and an electric tool, etc. The vehicle may be a fuel vehicle, a gas 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, etc. The spacecraft includes an aircraft, a rocket, a space shuttle, a spaceship, etc. The electric toys include stationary or mobile electric toys, such as a game machine, an electric toy car, an electric toy ship, an electric toy airplane, 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, planers, etc. 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 force to the vehicle and realize the operation of 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 cavity of the recess abuts against the current collecting part, so that a part of the end cap abuts against the surface of the current collecting part, thereby enhancing the adhesion of the contact surface between the end cap and the current collecting part, and improving the stability of the welding between the end cap and the current collecting part. At the same time, a fixed distribution area of ​​the welding mark is formed by the recess on the end cap, so that the welding position error during the welding process can be detected in a timely manner. In addition, by disposing a cover plate to cover the recess, such a configuration helps to reduce the area of ​​the recess exposed to the air, so that the oxidation in the welding area of ​​the end cap and the corrosion of the welding mark are slowed down, thereby reducing the probability of the welding connection failure between the end cap and the current collecting part, and the service life of the cylindrical battery cell is extended. In this way, the present invention effectively overcomes some practical problems in the prior art and has high utility value and usage significance. The above-mentioned embodiments are merely examples for illustrating the principle of the present invention and its effects, and do not limit the present invention. Those skilled in the art can modify or change the above-mentioned 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, the battery assembly, and the 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 First Tab 122 Second Tab 123 Center hole 130 Current collector 131 Thick wall part 132 Opening hole 133 Current collector body 140 End Cap 141 Recess 1411 Cavity bottom wall 1412 Cavity side wall 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 Section 143 Bending Mark 144 Cover body 150 cover plate 151 Main body 152 Connection 160 / 160' liquid injection hole 161 Stretching section 1611 Inner 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 Section

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 part; a cover plate disposed above the recess and covering the recess; A cylindrical battery cell comprising:

2. The cylindrical battery cell of claim 1 , wherein the cover plate is welded to the end cap.

3. 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.

4. The cylindrical battery cell of claim 1 , wherein the recess is disposed at a center of the end cap.

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

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

7. The cylindrical battery cell according to claim 5 , 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.

8. 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 connection portion arranged around the main body portion, the main body portion protruding in a direction opposite to the cavity bottom wall relative to the connection portion, and the connection portion abutting the cavity side wall.

9. 9. The cylindrical battery cell of claim 8, 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.

10. 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, and 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.

11. The cylindrical battery cell according to claim 1 , further comprising a venting mark disposed on the end cap.

12. 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.

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

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

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