Secondary battery, electronic equipment and manufacturing method of secondary battery

Abstract

The invention provides a secondary battery, electronic equipment and a manufacturing method of the secondary battery. The secondary battery comprises a shell, an electrode assembly, a cover plate and a current collecting component, one side of the shell is an open side, the other opposite side of the shell is a closed side, and the shell comprises a first barrel and a second barrel which are arranged in a segmented mode; one end of the first barrel is provided with an end wall to form a closed side, the other end of the first barrel comprises a first connecting section, one end of the second barrel is provided with an opening to form an open side, the other end of the second barrel comprises a second connecting section, the second connecting section is fixedly connected with the first connecting section, and a rolling groove which is sunken inwards is formed in the second barrel in a surrounding mode; the electrode assembly is accommodated in the shell; the cover plate is hermetically mounted at the opening; the current collecting component is arranged between the electrode assembly and the cover plate and comprises a tab connecting part and a shell connecting part, the tab connecting part is electrically connected with the tab, and the shell connecting part is electrically connected with the second cylinder; the technical problem that when a secondary battery adopts a mechanical sealing process, welding slag falls into a shell in the welding process of a current collecting component and the shell is solved.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and particularly to a secondary battery, an electronic device, and a manufacturing method of the secondary battery. Background Art

[0002] As one of the most core components of new energy vehicles, lithium-ion batteries have the advantages of high energy density, long cycle life, safety and environmental protection, and have gradually become the mainstream direction in the electrification era. Lithium-ion batteries are divided into hard-shell batteries, soft-pack batteries, and cylindrical batteries in terms of form. Among them, cylindrical batteries have attracted attention due to their high volumetric energy density, simple structure, easy grouping, and convenience for standardization.

[0003] The housing of a cylindrical battery is generally charged, so that the housing itself is used as one of the positive and negative electrodes when the batteries are grouped. The electrical connection mode between the electrode assembly inside the housing and the housing is as follows: the electrode assembly is welded to the current collector member, and the current collector member is connected to the housing or the cover plate, so as to realize the current conduction from the electrode assembly to the housing. The connection between the current collector member and the housing generally adopts a welding connection method. Among them, the problem that foreign matters generated by welding fall inside the housing and affect the electrical performance needs to be solved urgently. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the present invention provides a secondary battery, an electronic device, and a manufacturing method of the secondary battery to improve the technical problem that welding slag falls on the housing during the welding process of the current collector member and the housing when the secondary battery adopts a mechanical sealing process.

[0005] To achieve the above object and other related objects, the present invention provides a secondary battery, which includes: a housing, an electrode assembly, a cover plate, and a current collector member; one side of the housing is an open side, and the other side opposite in the height direction of the secondary battery is a closed side. The housing includes a first cylinder body and a second cylinder body that are arranged in sections along the height direction of the secondary battery; one end of the first cylinder body is provided with an end wall to form the closed side, and the other end of the first cylinder body includes a first connection section; one end of the second cylinder body is provided with an opening to form the open side, and the other end of the second cylinder body includes a second connection section. The second connection section is fixedly connected to the first connection section, and a rolling groove that is recessed inward is circumferentially arranged on the main body of the second cylinder body; the electrode assembly is accommodated in the housing and is arranged between the rolling groove and the end wall. The electrode assembly includes a tab facing the opening; the cover plate is hermetically installed on the opening; the current collector member is arranged between the electrode assembly and the cover plate and includes a tab connection portion and a housing connection portion. The tab connection portion is electrically connected to the tab, and the housing connection portion is electrically connected to the second cylinder body.

[0006] In an example of the secondary battery of the present invention, the first connection section and the second connection section at least partially overlap in the height direction of the secondary battery and form an overlapping area surrounding the housing.

[0007] In an example of the secondary battery of the present invention, the length of the overlapping region in the height direction of the secondary battery is 0.1 to 5 mm.

[0008] In an example of the secondary battery of the present invention, the second connecting section contracts inwardly into the second cylinder and has a diameter smaller than that of the first connecting section. The second connecting section is inserted inside the first connecting section and cooperates with the inner wall of the first connecting section to form an overlapping region.

[0009] In an example of the secondary battery of the present invention, the second connecting section contracts inwardly to form a first end face, and the first end face abuts against the first connecting section and is fixed by welding.

[0010] In an example of the secondary battery of the present invention, the second connecting section protrudes outwardly from the second cylinder and has a diameter larger than that of the first connecting section. The first connecting section is inserted inside the second connecting section, and the second connecting section cooperates with the outer wall of the first connecting section to form an overlapping region.

[0011] In an example of the secondary battery of the present invention, the second connecting section and the first connecting section are welded and connected in the overlapping region.

[0012] In an example of the secondary battery of the present invention, the first connecting section contracts inwardly into the first cylinder and has a diameter smaller than that of the second connecting section. The first connecting section is inserted inside the second connecting section and cooperates with the inner wall of the second connecting section to form an overlapping region.

[0013] In an example of the secondary battery of the present invention, the first connecting section contracts inwardly to form a second end face, and the second end face abuts against the second connecting section and is fixed by welding.

[0014] In an example of the secondary battery of the present invention, the first connecting section protrudes outwardly from the first cylinder and has a diameter larger than that of the second connecting section. The second connecting section is inserted inside the first connecting section, and the first connecting section cooperates with the outer wall of the second connecting section to form an overlapping region.

[0015] In an example of the secondary battery of the present invention, the first connecting section and the second connecting section are welded and connected in the overlapping region.

[0016] In an example of the secondary battery of the present invention, on the circumferential surface of the electrode assembly corresponding to the welding positions of the first connecting section and the second connecting section in the height direction of the secondary battery, a high-temperature resistant protective layer is provided.

[0017] In an example of the secondary battery of the present invention, the second connecting section and the first connecting section are welded and connected, and in the height direction of the secondary battery, the welding position of the second connecting section and the first connecting section corresponds to the height of the tab and / or the current collector member.

[0018] In an example of the secondary battery of the present invention, a rolling groove forms a protrusion inside the second cylinder. Along the height direction of the secondary battery, the distance between the side of the second cylinder close to the electrode assembly from the protrusion to the end of the second cylinder far from the opening is L, and L ≤ 15 mm.

[0019] In an example of the secondary battery of the present invention, the current collector member includes a central hole, the tab connection portion is disposed around the central hole, and the housing connection portion is disposed around the tab connection portion.

[0020] In an example of the secondary battery of the present invention, the housing connection portion and the tab connection portion are an integral circular flat sheet. The tab connection portion is welded to the tab, and the housing connection portion is welded to the side of the protrusion facing the electrode assembly.

[0021] In an example of the secondary battery of the present invention, the housing connection portion is welded to the side of the protrusion facing away from the electrode assembly. The tab connection portion is recessed toward the electrode assembly side relative to the housing connection portion and is welded to the tab.

[0022] In an example of the secondary battery of the present invention, the side of the second cylinder facing away from the electrode assembly includes a flanging extending toward the center of the opening, and the edge of the cover plate is sealed and pressed between the flanging and the protrusion.

[0023] In an example of the secondary battery of the present invention, a groove is formed between the flanging and the protrusion, and a seal is provided between the cover plate and the groove.

[0024] In an example of the secondary battery of the present invention, the seal surrounds and wraps the edge of the cover plate, and the flanging presses the seal and the cover plate.

[0025] In an example of the secondary battery of the present invention, a discharge portion is provided on the cover plate.

[0026] In an example of the secondary battery of the present invention, the discharge portion includes a notch provided on the cover plate, and the opening of the notch is close to the electrode assembly.

[0027] In an example of the secondary battery of the present invention, the cover plate includes a plurality of reinforcing ribs, and the plurality of reinforcing ribs are radially distributed with the axis of the cover plate as the center and extend along the radial direction of the cover plate.

[0028] In an example of the secondary battery of the present invention, both the first cylinder and the second cylinder are made of metal.

[0029] The present invention also provides an electronic device, and the electronic device includes a battery pack, and the battery pack includes a secondary battery.

[0030] In addition, a method for manufacturing a secondary battery according to one or more embodiments disclosed by the present invention may include the following steps:

[0031] Install the electrode assembly into the first cylinder;

[0032] Weld the current collector member to the second cylinder to form an integrated component;

[0033] Butt the integrated component against one end of the first cylinder, and weld and fix the second cylinder of the integrated component to the first cylinder;

[0034] Weld the current collector member and the tab on the side of the electrode assembly facing the current collector member; and

[0035] Seal and install the cover plate on the opening of the second cylinder facing away from the first cylinder.

[0036] In the method for manufacturing a secondary battery according to one or more embodiments disclosed in the present invention: the second cylinder includes a rolling groove recessed into the interior of the second cylinder, and the rolling groove forms a protrusion inside the second cylinder; weld the current collector member to the side of the protrusion close to the electrode assembly to form an integrated component.

[0037] In the method for manufacturing a secondary battery according to one or more embodiments disclosed in the present invention: the integrated component and one end of the first cylinder are nested to form an overlapping area; the second cylinder and the first cylinder are fixedly connected by irradiating a laser in the overlapping area, the electrode assembly is sleeved in the cavity formed by the first cylinder and the integrated component, and the current collector member abuts against the electrode assembly.

[0038] In the method for manufacturing a secondary battery according to one or more embodiments disclosed in the present invention: inject electrolyte into the opening before the step of sealing and installing the cover plate on the opening of the second cylinder.

[0039] For the secondary battery of the present invention, the housing includes a first cylinder and a second cylinder that are segmented along the height direction; one end of the first cylinder is provided with an end wall to form a closed side, and the other end of the first cylinder includes a first connection section; one end of the second cylinder is provided with an opening to form an open side, and the other end of the second cylinder includes a second connection section, the second connection section is fixedly connected to the first connection section, and a rolling groove recessed inward is circumferentially provided on the main body of the second cylinder; the current collector member is disposed between the electrode assembly and the cover plate, and includes a tab connection portion and a housing connection portion, the tab connection portion is electrically connected to the tab, and the housing connection portion is electrically connected to the second cylinder; by providing the rolling groove on the second cylinder, a mechanical sealing process with mature technology, low cost and high efficiency can be used.

[0040] The split design of the second cylinder and the first cylinder enables the welding process of the current collector member and the second cylinder to be carried out away from the first cylinder and the electrode assembly. First, it can prevent welding slag from falling into the secondary battery. In addition, when the current collector member and the second cylinder are welded, there is no blockage at both ends of the second cylinder, and the welding can be directly carried out inside the second cylinder, and the laser can be irradiated from one side of the current collector member, penetrate the relatively thin current collector member to the second cylinder, the welding process window is large, and the welding efficiency is high.

[0041] The manufacturing method of the present invention first welds the current collector member and the second cylinder to form an integrated component. By adopting the method of pre-welding the current collector member and the second cylinder before assembling the secondary battery, the risk of welding slag falling into the secondary battery is avoided, the welding process window between the current collector member and the housing is increased, and the production cost is reduced. Finally, the cover plate is hermetically installed on the opening of the second cylinder through a mechanical sealing process. While retaining the mechanical sealing process with mature technology, low cost and high efficiency, the process difficulties existing in the welding process between the current collector member and the housing in the prior art are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other embodiments can be obtained based on these drawings.

[0043] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the secondary battery of the present invention;

[0044] Figure 2 is Figure 1 a partial enlarged view of an example at A in

[0045] Figure 3 is Figure 2 a partial enlarged view of B in

[0046] Figure 4 is Figure 1 another partial enlarged view of A in

[0047] Figure 5 is Figure 4 a partial enlarged view of C in

[0048] Figure 6 is Figure 1 yet another partial enlarged view of A in

[0049] Figure 7 is Figure 6 a partial enlarged view of D in

[0050] Figure 8 is Figure 1 still another partial enlarged view of A in

[0051] Figure 9 is Figure 8 a partial enlarged view of E in

[0052] Figure 10 is Figure 1Partial enlarged view of an example at A in [the figure];

[0053] Figure 11 is Figure 10 Partial enlarged view at F in [the figure];

[0054] Figure 12 is Figure 1 Partial enlarged view of an example at A in [the figure];

[0055] Figure 13 is Figure 12 Partial enlarged view at G in [the figure];

[0056] Figure 14 Schematic diagram of the structure of an integrated component of an embodiment of the secondary battery of the present invention;

[0057] Figure 15 Partial sectional view of the first cylinder of an embodiment of the secondary battery of the present invention;

[0058] Figure 16 Schematic diagram of an embodiment of the electronic device of the present invention;

[0059] Figure 17 Schematic diagram of the structure of the battery pack of an embodiment of the electronic device of the present invention;

[0060] Figure 18 Flow chart of an embodiment of the manufacturing method of the secondary battery of the present invention.

[0061] Explanation of component numbers

[0062] 1. Electronic device; 10. Battery pack; 11. Working part; 101. Box body; 102. Box cover; 100. Secondary battery; 110. Housing; 111. First cylinder; 1111. End wall; 1112. First connection section; 1113. Second end face; 112. Second cylinder; 1121. Rolling groove; 1122. Protrusion; 1123. Opening; 1124. Groove; 1125. Flange; 1126. Second connection section; 1127. First end face; 113. First necking part; 1131. First welding mark; 114. First flaring part; 1141. Second welding mark; 115. Second necking part; 1151. Third welding mark; 116. Second flaring part; 1161. Fourth welding mark; 117. Overlapping area; 120. Electrode assembly; 121. Second tab; 122. First tab; 123. High-temperature protective layer; 130. First current collector member; 131. Tab connection part; 132. Housing connection part; 1321. Fifth welding mark; 1322. Sixth welding mark; 133. Central hole; 140. Second current collector member; 150. Terminal; 160. Cover plate; 161. Discharge part; 162. Notch; 163. Reinforcing rib; 164. First side; 165. Second side; 166. Third side; 170. Seal; 180. Integrated component. Detailed implementation manners

[0063] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can 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 specific implementation manners, rather than for limiting the protection scope of the present invention. The test methods without specific conditions noted in the following embodiments are usually carried out under conventional conditions or according to the conditions recommended by each manufacturer.

[0064] When the embodiments give a numerical range, it should be understood that unless otherwise stated in the present invention, any value between the two endpoints of each numerical range and any one value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are the same as those mastered by those skilled in the art of the present technology field and the description of the present invention. Any methods, devices, and materials similar or equivalent to the existing technologies in the methods, devices, and materials in the embodiments of the present invention can also be used to implement the present invention.

[0065] It should be noted that terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of clear narration and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships, without substantial changes in technical content, should also be regarded as the scope of implementation of the present invention.

[0066] Please refer to Figures 1 to 18 , the present invention provides a secondary battery 100, an electronic device 1, and a manufacturing method of the secondary battery 100. In the secondary battery 100, a housing 110 includes a first cylinder 111 and a second cylinder 112 that are segmented along the height direction of the secondary battery 100; for the height direction of the secondary battery 100, please refer to Figure 1 the direction indicated by Z in. One end of the first cylinder 111 is provided with an end wall 1111 to form a closed side, and the other end of the first cylinder 111 includes a first connection section 1112; one end of the second cylinder 112 is provided with an opening 1123 to form an open side, and the other end of the second cylinder 112 includes a second connection section 1126, and the second connection section 1126 is fixedly connected to the first connection section 1112. A rolling groove 1121 that is recessed inward is provided around the main body of the second cylinder 112; a first current collector member 130 is disposed between the electrode assembly 120 and the cover plate 160 and includes a tab connection portion 131 and a housing connection portion 132, and the housing connection portion 132 is electrically connected to the second cylinder 112; it improves the technical problem that there are process difficulties in the welding process between the first current collector member 130 and the housing 110 when the secondary battery 100 adopts a mechanical sealing process.

[0067] Please refer to Figure 1 , the secondary battery 100 of the present invention includes: a housing 110, an electrode assembly 120, a pole column 150, current collector members 130, 140, and a cover plate 160.

[0068] One side of the housing 110 is an open side, and the other side opposite to it along the height direction of the secondary battery 100 is a closed side. The housing 110 includes a first cylinder 111 and a second cylinder 112 that are segmented along the height direction of the secondary battery 100; the first cylinder 111 and the second cylinder 112 can be cylindrical or prismatic, or can be other cylinders surrounded by any closed-loop contour. The first cylinder 111 and the second cylinder 112 can have the same shape or different shapes. As an embodiment, in this embodiment, both the first cylinder 111 and the second cylinder 112 are cylindrical. One end of the first cylinder 111 is provided with an end wall 1111, and the shape of the end wall 1111 can be various, and it is preferably consistent with the shape surrounded by the first cylinder 111.

[0069] Please refer to Figures 1 to 3, one end of the first cylinder 111 is provided with an end wall 1111 to form a closed side, and the other end of the first cylinder 111 includes a first connection section 1112; one end of the second cylinder 112 is provided with an opening 1123 to form an open side, and the other end of the second cylinder 112 includes a second connection section 1126, and the second connection section 1126 is fixedly connected to the first connection section 1112 to realize the fixed connection between the other end of the first cylinder 111 and the second cylinder 112; the ways of fixed connection include threaded connection, tenon connection, welding connection, bonding, etc., but are not limited to the above. The housing 110 of the secondary battery 100 needs to be charged, so the materials of the first cylinder 111 and the second cylinder 112 are metals, such as copper, iron, aluminum, steel, aluminum alloy, etc. The materials of the first cylinder 111 and the second cylinder 112 can be the same or different. Considering the high sealing requirements of the housing 110 of the secondary battery 100, in this embodiment, the first cylinder 111 and the second cylinder 112 are fixedly connected by welding. As long as the sealed connection between the first cylinder 111 and the second cylinder 112 can be realized, the welding position and the shape of the weld mark between the first cylinder 111 and the second cylinder 112 are not limited. In addition, in order to prevent the housing 110 from rusting during long-term use, after the first cylinder 111 and the second cylinder 112 are welded and fixed, a layer of anti-rust material such as metallic nickel can be plated on the surface of the housing 110. An accommodation cavity is formed inside the housing 110 surrounded by the first cylinder 111 and the first cylinder 111 for accommodating the electrode assembly 120, the electrolyte (not shown), and other necessary battery components. The diameters of the first cylinder 111 and the second cylinder 112 can be determined according to the specific size of the electrode assembly 120, such as 18mm, 21mm, 46mm, etc.

[0070] Please refer to Figures 1 to 14, one end of the second cylinder body 112 is provided with an opening 1123 to form an opening side. Since mechanical sealing has the advantages of mature technology, equipment, and fast production rhythm, the mechanical sealing process is adopted for sealing. Specifically, a rolling groove 1121 recessed towards the inside of the second cylinder body 112 is circumferentially provided on the main body of the second cylinder body 112, and a protrusion 1122 is formed inside the second cylinder body 112 by the rolling groove 1121; in an example of the secondary battery 100 of the present invention, the edge of the cover plate 160 is placed on the side of the protrusion 1122 facing the opening 1123. Then, the side wall of the opening end of the second cylinder body 112 is flanged towards the center of the opening 1123 by the pier sealing process, and a groove 1124 is formed between the flange 1125 and the protrusion 1122. The edge of the cover plate 160 is hermetically press-fitted between the flange 1125 and the protrusion 1122 and is located in the groove 1124. Specifically, the surface of the cover plate 160 cooperating with the groove 1124 includes a first side surface 164 close to the protrusion 1122, a second side surface 165 close to the bottom of the groove 1124, and a third side surface 166 close to the flange 1125. There are various sealing methods for the cover plate 160. For example, sealant is filled between the edge of the cover plate 160 and the groove 1124, a sealing coating is applied to the edge of the cover plate 160, or a seal 170 is provided between the cover plate 160 and the groove 1124, etc. Preferably, in this embodiment, a seal 170 is provided between the cover plate 160 and the groove 1124. The material of the seal 170 can be rubber, metal, graphite, or polytetrafluoroethylene, etc., and the cross-sectional shape can be an O-ring, an L-ring, etc. In this embodiment, the seal 170 is made of rubber material and its shape is a structure that surrounds and wraps the edge of the cover plate 160. Specifically, the seal ring adopts a form that wraps the first side surface 164, the second side surface 165, and the third side surface 166 of the cover plate 160, such as Figure 7 shown. In addition, since the high temperature generated during welding will cause the electrolyte inside the secondary battery 100 to decompose when using welding for sealing, the mechanical sealing method can be adopted to improve the problem of electrolyte decomposition.

[0071] Please refer to Figures 1 to 2, the electrode assembly 120 is accommodated within the housing 110 and is disposed between the rolling groove 1121 and the end wall 1111. The protrusion 1122 formed by the rolling groove 1121 can limit the axial displacement of the electrode assembly 120. The electrode assembly 120 is a component in the secondary battery 100 where an electrochemical reaction occurs. One or more electrode assemblies 120 may be included within the housing 110. The electrode assembly 120 is mainly formed by winding or laminating a positive electrode plate and a negative electrode plate, and a separator is usually provided between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode active material, and the positive electrode active material is coated on the surface of the positive electrode current collector; the positive electrode current collector includes a coated area coated with the active material and an uncoated area not coated with the active material, and the uncoated area forms the positive electrode tab of the electrode assembly 120 after winding. The negative electrode plate includes a negative electrode current collector and a negative electrode active material, and the negative electrode active material is coated on the surface of the negative electrode current collector; the negative electrode current collector includes a coated area coated with the active material and an uncoated area not coated with the active material, and the uncoated area forms the negative electrode tab of the electrode assembly 120 after winding. Taking the lithium-ion secondary battery 100 as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material includes the positive electrode active material, which can be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, etc. The material of the negative electrode current collector can be copper, and the negative electrode active material includes the negative electrode active material, which can be carbon or silicon, etc. The material of the separator can be PP (polypropylene) or PE (polyethylene), etc. To protect and insulate the battery cell, an insulating film can also be wrapped around the outside of the battery cell, and the insulating film can be synthesized from PP, PE, PET, PVC, or other polymer materials.

[0072] Please refer to Figure 1, in the electrode assembly 120 of the present invention, there are two tab ears 121 and 122, one facing the end wall 1111 and the other facing the opening 1123. For the convenience of distinction, the tab ear facing the opening 1123 is named the first tab ear 122, and the tab ear facing the end wall 1111 is named the second tab ear 121. The second tab ear 121 can be a positive tab ear or a negative tab ear. The electric property of the first tab ear 122 is opposite to that of the second tab ear 121. When the second tab ear 121 is a positive tab ear, the first tab ear 122 is a negative tab ear; when the second tab ear 121 is a negative tab ear, the first tab ear 122 is a positive tab ear. Both tab ears are connected with current collector members 130 and 140. Similarly, for the convenience of distinction, the current collector member connected to the first tab ear 122 is named the first current collector member 130, and the current collector member connected to the second tab ear 121 is named the second current collector member 140. The second tab ear 121 is electrically connected to the pole post 150 through the second current collector member 140. The first current collector member 130 is arranged at one end of the electrode assembly 120 facing the opening 1123 and is welded to the first tab ear 122. In this embodiment, the second tab ear 121 is a positive tab ear, the pole post 150 is electrically connected to the second tab ear 121 and is positively charged, the first tab ear 122 is a negative tab ear, and the side of the opening 1123 of the housing 110 opposite to the end wall 1111 is electrically connected to the first tab ear 122, thus being negatively charged.

[0073] Please refer to Figure 1 , on the end wall 1111 of the first cylinder 111, a pole post 150 is installed. The pole post 150 passes through the end wall 1111 and is insulated from the end wall 1111. The structural form of the pole post 150 can be any suitable form that can pass through the end wall 1111 and be electrically connected to the second tab ear 121 of the electrode assembly 120. For example, the cross-section can be circular, square, prismatic, or a special-shaped profile that can achieve stable electrical conduction. In this embodiment, a pole post installation hole is provided on the end wall 1111, and the pole post 150 is hermetically and insulatingly installed in the pole post installation hole. This housing 110 structure can improve the installation efficiency, and the assembly and sealing performance are better than those of the housing 110 form with openings 1123 at both ends. One end of the pole post 150 facing the electrode assembly 120 passes through the end wall 1111 and is directly electrically connected to the second tab ear 121 or indirectly connected through a transfer connection. In this embodiment, the pole post 150 is connected to the second tab ear 121 through the second current collector member 140 for transfer connection. One end of the pole post 150 facing the opening 1123 is welded to the second current collector member 140, and the side of the second current collector member 140 facing away from the pole post 150 is welded to the second tab ear 121. The end of the pole post 150 facing away from the electrode assembly 120 is exposed to the outside of the housing 110 to form a connection surface for connecting an external bus bar.

[0074] Please refer to Figures 1 to 2, the first current collector member 130 is disposed between the electrode assembly 120 and the cover plate 160. The structure of the first current collector member 130 is not limited. For example, it can be any structure that forms an electrical connection with the electrode assembly 120 and the housing 110. The first current collector member 130 includes a tab connection portion 131 and a housing connection portion 132. The side of the tab connection portion 131 close to the electrode assembly 120 is electrically connected to the first tab 122. The electrical connection method can be a direct fixed connection or an electrical connection through an adapter. In this embodiment, the electrical connection method between the tab connection portion 131 and the first tab 122 is a welding connection, including but not limited to laser welding. The housing connection portion 132 is electrically connected to the second cylinder 112. The electrical connection method can be a direct fixed connection or an electrical connection through an adapter. In this embodiment, the housing connection portion 132 and the second cylinder 112 are connected by welding, including but not limited to laser welding. The position where the housing connection portion 132 is connected to the second cylinder 112 is not limited. It can be that the circumferential direction of the housing connection portion 132 is welded to the inner wall of the second cylinder 112, or the housing connection portion 132 is welded to the protrusion 1122. As long as a reliable connection between the housing connection portion 132 and the second cylinder 112 can be achieved. In this embodiment, the housing connection portion 132 is welded to the protrusion 1122. This welding method has a large welding process window and is firmly welded.

[0075] Please refer to Figures 1 to 3 and Figure 14 , in the secondary battery 100 of the present invention, the split design of the second cylinder 112 and the first cylinder 111 enables the welding process of the first current collector member 130 and the second cylinder 112 to be carried out away from the first cylinder 111 and the electrode assembly 120. First, it can prevent welding slag from falling into the secondary battery 100. In addition, when the first current collector member 130 and the second cylinder 112 are welded, the cover plate 160 has not been installed yet, so there is no blockage at both ends of the second cylinder 112, and welding can be directly carried out inside the second cylinder 112. Moreover, the laser can irradiate from one side of the first current collector member 130, penetrate through the relatively thin first current collector member 130 to the second cylinder 112. The welding process window is large and the welding efficiency is high. While retaining the mechanically sealed process with mature technology, low cost and high efficiency, the process difficulties existing in the welding process of the first current collector member 130 and the housing 110 in the prior art are improved.

[0076] Please refer to Figure 7, considering the reliability of the fixed connection between the first cylinder 111 and the second cylinder 112, in an example of the secondary battery 100 of the present invention, the first connection section 1112 and the second connection section 1126 at least partially overlap in the height direction of the secondary battery 100 and form an overlapping area 117 surrounding the housing 110. When the first cylinder 111 and the second cylinder 112 are connected by threads, the overlapping area 117 is used to construct the threads. When the first cylinder 111 and the second cylinder 112 are connected by tenons, the overlapping area 117 is used to construct the mortise and tenon. When the first cylinder 111 and the second cylinder 112 are connected by welding, the overlapping area 117 is used for positioning and pre-fixing before welding on the one hand, making the welding easy to operate. On the other hand, it can provide conditions for penetration welding. On the third hand, it can be used to block the laser during welding to reduce the high temperature damage to the electrode assembly 120 caused by welding; the overlapping area 117 can be formed by inserting the first connection section 1112 of the first cylinder 111 into the second connection section 1126 of the second cylinder 112, or by inserting the second connection section 1126 of the second cylinder 112 into the first connection section 1112 of the first cylinder 111.

[0077] Preferably, in an example of the secondary battery 100 of the present invention, the length of the overlapping area 117 in the height direction of the secondary battery 100 is shown by S. Please refer to Figure 7 , the range of S is 0.1 - 5 mm. The specific length of S can be correspondingly selected according to the specific connection method between the first cylinder 111 and the second cylinder 112. When the first cylinder 111 and the second cylinder 112 are connected by welding, the setting of this range is beneficial to the welding stability between the first cylinder 111 and the second cylinder 112 and can reduce the thermal influence of the welding heat on the electrode assembly 120.

[0078] Please refer to Figures 2 to 3 and Figure 7 , in an example of the secondary battery 100 of the present invention, the second connection section 1126 shrinks towards the inside of the second cylinder 112 and has a diameter smaller than that of the first connection section 1112. The second connection section 1126 is inserted inside the first connection section 1112 and cooperates with the inner wall of the first connection section 1112 to form the overlapping area 117. In order to distinguish it from other embodiments, the second connection section 1126 here is named the first reduced diameter part 113. The setting of the first reduced diameter part 113 plays a guiding role when the second cylinder 112 is installed on the first cylinder 111 on the one hand, and can block the laser during welding to reduce the damage to the electrode assembly 120 caused by high temperature on the other hand. On the third hand, the first reduced diameter part 113 shrinks towards the inside of the second cylinder 112, so that the outer walls of the first cylinder 111 and the second cylinder 112 are aligned and flat, which is convenient for the module space occupied by a single battery cell to be smaller when multiple batteries are connected in series and parallel.

[0079] Preferably, in this embodiment, the second connecting section 1126, i.e., the first necking section 113, contracts inward to form a first end face 1127. Please refer to Figure 14 , the first end face 1127 abuts against the first connecting section 1112 and is fixed by welding. Welding connection is performed on the contact surface between the end face of the first connecting section 1112 and the first end face 1127 to form a first welding mark 1131 as shown in Figure 3 . Seam welding is used for welding, which has low cost, high efficiency and reliable welding. It should be noted that the fit between the first necking section 113 and the inner wall of the first connecting section 1112 is preferably an interference fit, which is beneficial to improving the sealing performance and positioning function of the welding between the first cylinder 111 and the second cylinder 112, and at the same time is beneficial to reducing the possibility of welding slag generated during welding falling into the secondary battery 100.

[0080] Please refer to Figures 4 to 5 and Figure 7 . In another example of the secondary battery 100 of the present invention, the second connecting section 1126 protrudes outward from the second cylinder 112 and has a diameter larger than that of the first connecting section 1112. The first connecting section 1112 is inserted into the inner side of the second connecting section 1126, and the second connecting section 1126 cooperates with the outer wall of the first connecting section 1112 to form an overlapping area 117. In order to distinguish it from other embodiments, the second connecting section 1126 here is named the first flaring section 114. The setting of the first flaring section 114, on the one hand, plays a guiding role when the second cylinder 112 is installed on the first cylinder 111. On the other hand, the first flaring section 114 protrudes outward from the second cylinder 112, which can reduce the risk of the second cylinder 112 rubbing against the electrode assembly 120 when the second cylinder 112 is installed on the first cylinder 111.

[0081] Preferably, in this embodiment, the second connecting section 1126, i.e., the first flaring section 114, is welded to the first connecting section 1112 in the overlapping area 117. The welding between the first flaring section 114 and the first connecting section 1112 can adopt seam welding or penetration welding. Seam welding is adopted in this embodiment. Specifically, a second welding mark 1141 surrounding the first connecting section 1112 is formed on the contact surface between the inner wall of the first flaring section 114 and the outer wall of the first connecting section 1112. Please refer to Figure 5 . Seam welding is used for welding, which has low cost, high efficiency and reliable welding. At the same time, the welding slag formed by this welding method will not have the risk of falling into the secondary battery 100. In addition, the direction of laser irradiation is along the height direction of the secondary battery 100, reducing the damage of the high temperature generated by the laser to the electrode assembly 120.

[0082] Please refer to Figures 6 to 7, in another example of the secondary battery 100 of the present invention, the first connecting section 1112 contracts towards the inside of the first cylinder 111 and has a diameter smaller than that of the second connecting section 1126. The first connecting section 1112 is inserted inside the second connecting section 1126 and cooperates with the inner wall of the second connecting section 1126 to form an overlapping area 117. For the purpose of distinguishing from other embodiments, the first connecting section 1112 here is named the second necking section 115. The setting of the second necking section 115, on the one hand, plays a guiding role when the second cylinder 112 is mounted on the first cylinder 111. On the other hand, the second necking section 115 is provided on the first cylinder 111, which can reduce the risk of the second cylinder 112 rubbing against the electrode assembly 120 when the second cylinder 112 is mounted on the first cylinder 111. The second necking section 115 can also block the laser during welding to reduce the damage to the electrode assembly 120 caused by high temperature. In addition, the second necking section 115 contracts towards the inside of the first cylinder 111, so that the outer walls of the first cylinder 111 and the second cylinder 112 are aligned and flat, which is convenient for the module space occupied by a single battery cell to be smaller when multiple batteries are connected in series or parallel.

[0083] Preferably, in this embodiment, the first connecting section 1112, that is, the second necking section 115, contracts towards the inside and forms a second end face 1113. Please refer to Figure 15 , the second end face 1113 abuts against the second connecting section 1126 and is fixed by welding. A welded connection is formed on the contact surface between the end face of the second connecting section 1126 and the second end face 1113 to form a third weld mark 1151 as shown in Figure 7 . The seam welding method is adopted for welding, which has low cost, high efficiency and reliable welding. It should be noted that the cooperation between the second necking section 115 and the inner wall of the second connecting section 1126 is preferably an interference fit, which is beneficial to improving the sealing performance and positioning function of the welding between the first cylinder 111 and the second cylinder 112, and at the same time is beneficial to reducing the possibility of welding slag falling into the secondary battery 100 during welding.

[0084] Please refer to Figures 7 to 9 , in another example of the secondary battery 100 of the present invention, the first connecting section 1112 protrudes towards the outside of the first cylinder 111 and has a diameter larger than that of the second connecting section 1126. The second connecting section 1126 is inserted inside the first connecting section 1112. The first connecting section 1112 cooperates with the outer wall of the second connecting section 1126 to form an overlapping area 117. For the purpose of distinguishing from other embodiments, the first connecting section 1112 here is named the second flaring section 116. The setting of the second flaring section 116, on the one hand, plays a guiding role when the second cylinder 112 is mounted on the first cylinder 111. On the other hand, the second flaring section 116 protrudes towards the outside of the first cylinder 111, which can reduce the risk of the second cylinder 112 rubbing against the electrode assembly 120 when the second cylinder 112 is mounted on the first cylinder 111.

[0085] Preferably, in the embodiment, the first connecting section 1112, i.e., the second flaring portion 116 and the second connecting section 1126 are welded and connected in the overlapping area 117. The welding of the second flaring portion 116 and the second connecting section 1126 can adopt seam welding or penetration welding. In this embodiment, seam welding is adopted. Specifically, a fourth welding mark 1161 surrounding the second connecting section 1126 is formed on the contact surface between the inner wall of the second flaring portion 116 and the outer wall of the second connecting section 1126. Please refer to Figure 9 , by adopting the way of seam welding, the cost is low, the efficiency is high and the welding is firm and reliable. At the same time, the welding slag formed by this welding method will not have the risk of falling into the secondary battery 100. In addition, the direction of laser irradiation is along the height direction of the secondary battery 100, reducing the damage to the electrode assembly 120 caused by the high temperature generated by the laser.

[0086] Please refer to Figure 3 , considering that the high temperature generated during the welding of the first connecting section 1112 and the second connecting section 1126 will damage the electrode assembly 120, in an example of the secondary battery 100 of the present invention, a high-temperature resistant protective layer 123 is provided on the peripheral surface of the electrode assembly 120 corresponding to the welding position of the first connecting section 1112 and the second connecting section 1126. The high-temperature resistant protective layer 123 can be in various ways, such as winding a high-temperature resistant tape on the peripheral surface of the electrode assembly 120, or coating a high-temperature resistant coating.

[0087] Please refer to Figures 10 to 11 , in an example of the secondary battery 100 of the present invention, the second connecting section 1126 is welded and connected to the first connecting section 1112. In the height direction of the secondary battery 100, the welding position of the second connecting section 1126 and the first connecting section 1112 corresponds to the height of the first tab 122 and / or the first current collector member 130, so as to ensure that the high temperature generated during the welding of the second connecting section 1126 and the first connecting section 1112 will not affect the coating area of the electrode assembly 120. It should be noted that the cooperation mode and welding form of the second connecting section 1126 and the first connecting section 1112 in this embodiment can adopt any one of the ways shown in Figures 2 to 9 , it should be noted that the shapes of all the above Figures 2 to 9 welding marks are only for illustration and are not used to limit the shape of the welding marks.

[0088] Please refer to Figure 3 、 Figure 5 、 Figure 7 and Figure 9, in an example of the secondary battery 100 of the present invention, in the height direction of the secondary battery 100, the distance between the second cylinder 112 from the side of the protrusion 1122 close to the electrode assembly 120 to the end of the second cylinder 112 away from the opening 1123 is L, and L≤15mm. The setting that the length of L does not exceed 15mm ensures that the first cylinder 111 has enough length to accommodate the electrode assembly 120 and gives a stable constraint to the electrode assembly 120 to prevent the electrode assembly 120 from falling out. When the second cylinder 112 is installed on the first cylinder 111, it reduces the risk of the second cylinder 112 rubbing against the electrode assembly 120. At the same time, it makes the operation more convenient when the second cylinder 112 is welded to the first current collector member 130.

[0089] In the prior art, when using the mechanical sealing process, the first current collector member 130 is generally welded to the housing 110 by first welding the housing connection portion 132 of the first current collector member 130 to the inner wall of the housing 110, and then grooving 1121 the housing connection portion 132 and the housing 110 together to press the housing connection portion 132 between the groove 1121 and the electrode assembly 120. This process is prone to breaking the housing connection portion 132 or causing the inner part of the first current collector member 130 to warp due to the bending of the housing connection portion 132, which may further lead to the fracture of the welding joint between the ear connection portion 131 and the first ear 122, resulting in the risk of electrical connection failure of the electrode assembly 120. To solve the above problems, it is necessary to spend manpower and material resources to design and process various forms of the first current collector member 130 for this welding process. In an example of the secondary battery 100 of the present invention, please refer to Figures 2 to 14 , the first current collector member 130 includes a central hole 133, the ear connection portion 131 is arranged around the central hole 133, and the housing connection portion 132 is arranged around the ear connection portion 131. The present invention reduces the requirements for the structure of the first current collector member 130, simplifies the structure of the first current collector member 130, reduces the production cost, and improves the production efficiency.

[0090] Please refer to Figures 2 to 11 , in an example of the secondary battery 100 of the present invention, the housing connection portion 132 and the ear connection portion 131 are an integral circular flat sheet. The ear connection portion 131 is welded to the ear. The first current collector member 130 is arranged as a circular flat sheet, which reduces the production cost, reduces the difficulty of processing and assembly, and improves the production efficiency. Preferably, the housing connection portion 132 is welded to the side of the protrusion 1122 close to the electrode assembly 120, and a fifth weld mark 1321 is formed on the side of the housing connection portion 132 close to the electrode assembly 120, as Figure 3As shown, since the thickness of the first current collector member 130 is thinner than the wall thickness of the second cylinder 112, laser is used to irradiate from one side of the first current collector member 130, penetrate through the relatively thin first current collector member 130 to the second cylinder 112. The welding process window is large and the welding efficiency is high. In addition, structurally, the housing connection portion 132 is located between the electrode assembly 120 and the protrusion 1122. When the second cylinder 112 is installed on the first cylinder 111, the pressure exerted by the electrode assembly 120 on the first current collector member 130 is beneficial to press-fit the first current collector member 130 and the first tab 122 tightly, facilitating the welding between the first current collector member 130 and the first tab 122.

[0091] Please refer to Figures 12 to 14 , in another example of the secondary battery 100 of the present invention, the housing connection portion 132 is welded to the side of the protrusion 1122 facing away from the electrode assembly 120, and a sixth weld mark 1322 is formed on the side of the housing connection portion 132 facing away from the electrode assembly 120, as Figure 13 shown. Since the thickness of the first current collector member 130 is thinner than the wall thickness of the second cylinder 112, laser is used to irradiate from one side of the first current collector member 130, penetrate through the relatively thin first current collector member 130 to the second cylinder 112. The welding process window is large and the welding efficiency is high. The tab connection portion 131 is recessed toward the electrode assembly 120 side relative to the housing connection portion 132 and is welded to the first tab 122. Structurally, the housing connection portion 132 is located on the side of the protrusion 1122 facing away from the electrode assembly 120, which means that the housing connection portion 132 is pressed together with the flanging 1125 during mechanical sealing, improving the connection stability between the housing connection portion 132 and the protrusion 1122. In addition, the cover plate 160 may or may not contact the housing connection portion 132, which is not limited. In one embodiment, the cover plate 160 contacts the housing connection portion 132, and the pressure exerted by the flanging 1125 on the housing connection portion 132 through the cover plate 160 is beneficial to press-fit the tab connection portion 131 and the first tab 122 tightly, facilitating the welding between the first current collector member 130 and the first tab 122.

[0092] Please refer to Figure 2 , Figure 4 , Figure 6 , Figure 8 , Figure 10 and Figure 12 , in one example of the secondary battery 100 of the present invention, a discharge portion 161 is provided on the cover plate 160. The discharge portion 161 is used to at least partially open when the internal air pressure in the housing 110 reaches a certain level to release the pressure inside the housing 110. The type of the explosion-proof structure is not limited. For example, it can be an explosion-proof valve assembly installed on the cover plate 160.

[0093] Please refer to Figure 2 , Figure 4 ,Figure 6 , Figure 8 , Figure 10 and Figure 12 , in an example of the secondary battery 100 of the present invention, the discharge portion 161 includes a notch 162 provided on the cover plate 160, and the notch 162 has an annular structure. It should be noted that the annular structure does not limit the notch 162 to be circular or elliptical. In the present invention, as long as the notch 162 is connected end to end, it can be considered an annular structure. Of course, in other embodiments, the notch 162 may not be connected end to end. For example, it may be in a C shape, a cross shape or other non-annular profiles, as long as it can be opened when the pressure is greater than the set threshold. With this setting, the position where the notch 162 is located is a region with relatively weak strength of the cover plate 160. When the air pressure inside the housing 110 exceeds a certain threshold (which can be achieved by calculating the strength at the notch 162 so that at least part of it opens when the air pressure exceeds a certain threshold), at this time, the air pressure inside the housing 110 is discharged from the rupture, thereby preventing the secondary battery 100 from exploding at the housing 110 and causing thermal runaway at the module level. Considering that the notch 162 will damage the nickel plating layer on the surface of the cover plate 160, and thus it is easy to rust at the position of the notch 162. Preferably, the opening 1123 of the notch 162 is provided on the side of the cover plate 160 facing the electrode assembly 120. In this way, the notch 162 is located in the enclosed space inside the housing 110, reducing the contact between the notch 162 and the air, which can slow down the rusting degree of the notch 162 and improve the service life of the notch 162.

[0094] Please refer to Figure 2 , Figure 4 , Figure 6 , Figure 8 , Figure 10 and Figure 12 , in an example of the secondary battery 100 of the present invention, the cover plate 160 includes a plurality of reinforcing ribs 163. The plurality of reinforcing ribs 163 are radially distributed around the axis of the cover plate 160 and extend along the radial direction of the cover plate 160. In this embodiment, eight reinforcing ribs 163 are provided and are evenly distributed circumferentially on the cover plate 160. The reinforcing ribs 163 are provided as integrally formed protrusions 1122, and the protrusions 1122 are formed on the side of the cover plate 160 facing away from the electrode assembly 120. This setting improves the strength of the cover plate 160 without increasing the material cost and the weight of the cover plate 160.

[0095] Please refer to Figure 16, the present invention also provides an electronic device 1, which includes a battery pack 10. The working part 11 is electrically connected to the battery pack 10 to obtain electrical energy support. As an example, the electronic device 1 is a vehicle, which can be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle, a range-extended vehicle, etc., but is not limited thereto. The working part 11 is the vehicle body, and the battery pack 10 is arranged at the bottom of the vehicle body and provides electrical energy support for the running of the vehicle or the operation of the electrical components in the vehicle. However, in some other embodiments, the electronic device 1 can also be a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, etc.; the working part 11 can be a unit component that can obtain the electrical energy of the battery pack 10 and perform corresponding work, such as the fan blade rotation unit of a fan, the dust suction working unit of a vacuum cleaner, etc. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and a railway electric tool, such as an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator, an electric planer, etc. The embodiments of the present application do not impose special restrictions on the above-mentioned electronic device 1.

[0096] Please refer to Figure 17 , the above-mentioned battery pack 10 includes the secondary battery 100 of any one of the above. In an embodiment of the battery pack 10 of the present invention, the battery pack 10 includes a box body 101, a box cover 102, and a plurality of secondary batteries 100. The plurality of secondary batteries 100 are placed in the box body 101 and are connected in series or in parallel with each other, or in a mixed connection of series and parallel. The box cover 102 covers the box body 101 to protect the plurality of secondary batteries 100. It should be noted that in addition to the secondary battery 100 of the present invention, the battery pack 10 can also include parts such as a battery pack thermal management system and a circuit board. The battery pack 10 can be a battery module or a battery pack, an energy storage cabinet, etc.; details will not be elaborated here one by one.

[0097] In addition, please refer to Figure 18 , a method for manufacturing the secondary battery 100 according to one or more embodiments disclosed in the present invention may include the following steps:

[0098] Please refer to Figure 1 , install the electrode assembly 120 onto the first cylinder 111; this step can be installed with reference to the form in which the electrode assembly 120 is installed in the housing 110 in the prior art, and details will not be elaborated here.

[0099] Please refer to Figures 1 to 14 , weld and connect the first current collector member 130 and the second cylinder 112 to form an integrated component 180. Please refer to Figure 14; Specifically, first, a rolling groove 1121 recessed into the interior of the second cylinder 112 is machined on the second cylinder 112. The rolling groove 1121 forms a protrusion 1122 inside the second cylinder 112. Then, the first current collector member 130 is welded to the protrusion 1122, and it can be welded to the side of the protrusion 1122 facing away from the electrode assembly 120, as Figures 12 to 13 shown, or welded to the side of the protrusion 1122 close to the electrode assembly 120, as Figures 2 to 11 shown, to form the integrated component 180. Please refer to Figure 14 . This step completes the pre-welding of the first current collector member 130 and the second cylinder 112, fundamentally changing the welding method between the first current collector member 130 and the housing 110, avoiding the risk of welding slag falling into the secondary battery 100, and at the same time eliminating the process difficulties existing in the welding process between the first current collector member 130 and the housing 110 in the prior art. There is no need to accurately position the first current collector member 130, reducing the positioning process, increasing the welding process window between the first current collector member 130 and the housing 110, and also reducing the production cost. It should be noted that the order of this step and the installation of the electrode assembly 120 into the first cylinder 111 is not sequential and does not affect each other.

[0100] Please refer to Figures 2 to 11 , dock the integrated component 180 with one end of the first cylinder 111, and weld and fix the second cylinder 112 of the integrated component 180 to the first cylinder 111; specifically, the integrated component 180 and one end of the first cylinder 111 are nested to form an overlapping area 117. Please refer to Figure 7 . The second cylinder 112 and the first cylinder 111 are fixedly connected by irradiating a laser in the overlapping area 117. The electrode assembly 120 is sleeved in the cavity formed by the first cylinder 111 and the integrated component 180, and the first current collector member 130 abuts against the electrode assembly 120. It should be noted that the second cylinder 112 and the first cylinder 111 can be welded and fixed by using the cooperation and welding method of any one of the above embodiments. Please refer to Figures 2 to 11 .

[0101] Please refer to Figures 1 to 2, welding is performed on the first current collector member 130 and the first tab 122 on the side of the electrode assembly 120 facing the opening 1123 from inside the opening 1123; specifically, the second cylinder 112 includes a rolling groove 1121 recessed into the interior of the second cylinder 112, and the rolling groove 1121 forms a protrusion 1122 inside the second cylinder 112; the first current collector member 130 is welded to the side of the protrusion 1122 close to the electrode assembly 120 to form an integrated component 180. In the prior art, the first current collector member 130 and the first tab 122 are welded first, and then the rolling groove 1121 is formed. Because of the bending of the connecting portion of the housing 110 of the first current collector member 130, the inside of the first current collector member 130 warps, which in turn causes the welding joint between the tab connecting portion 131 and the first tab 122 to break, resulting in the risk of electrical connection failure of the electrode assembly 120. In this embodiment, in this step, the welding of the first current collector member 130 and the first tab 122 is performed after the rolling groove 1121 of the second cylinder 112. The change in the process sequence can reduce the possibility of the welding joint between the tab connecting portion 131 and the first tab 122 breaking.

[0102] Please refer to Figures 2 to 13 The cover plate 160 is hermetically installed on the opening 1123 of the second cylinder 112 facing away from the first cylinder 111, and there are various encapsulation methods. Preferably, a mechanical sealing process is used for encapsulation. Specifically, the edge of the cover plate 160 is placed on the side of the protrusion 1122 facing the opening 1123. Then, a caulking process is used to bend the side wall of the open end of the second cylinder 112 towards the center of the opening 1123, and a groove 1124 is formed between the flanging 1125 and the protrusion 1122. The edge of the cover plate 160 is hermetically press-fitted between the flanging 1125 and the protrusion 1122. This step has a mature process, low cost and high efficiency. In addition, since the high temperature generated during welding when using welding for sealing will cause the electrolyte inside the secondary battery 100 to decompose, therefore, using the mechanical sealing method can improve the problem of electrolyte decomposition.

[0103] Further, the manufacturing method further includes injecting electrolyte. The injection method of the electrolyte is not limited. It can be selected to inject through the opening 1123, or it can be selected to set an injection hole on the end wall 1111 for injection; preferably, in this embodiment, the electrolyte is injected through the opening 1123, which reduces the process of opening an injection hole on the end wall 1111 and can directly use the existing opening 1123 for injection, simplifying the process and reducing the cost.

[0104] It should be noted that Figure 18 This is only the process of one embodiment of the manufacturing method. The order of the steps in this method can be adaptively adjusted according to the actual situation and is not limited by Figure 18 .

[0105] For the secondary battery of the present invention, one side of the housing is the open side, and the other side opposite in the height direction of the secondary battery is the closed side. The housing includes a first cylinder and a second cylinder which are arranged in sections along the height direction; one end of the second cylinder is provided with an opening to form the open side, and the other end of the second cylinder includes a second connection section, and the second connection section is fixedly connected to the first connection section. A rolling groove recessed inward is circumferentially provided on the main body of the second cylinder; the first current collector member is arranged between the electrode assembly and the cover plate and includes an ear connection portion and a housing connection portion, and the housing connection portion is electrically connected to the second cylinder; the split design of the second cylinder and the first cylinder enables the welding process of the first current collector member and the second cylinder to be carried out away from the first cylinder and the electrode assembly. Firstly, it can prevent welding slag from falling into the secondary battery. In addition, when the first current collector member and the second cylinder are welded, there is no obstruction at both ends of the second cylinder, and welding can be directly carried out inside the second cylinder, and the laser can irradiate from one side of the first current collector member, penetrate through the relatively thin first current collector member to the second cylinder, with a large welding process window and high welding efficiency. For the control method of the present invention, the first current collector member and the second cylinder are first welded and connected to form an integrated component. By adopting the method of pre-welding the first current collector member and the second cylinder before assembling the secondary battery, the risk of welding slag falling into the secondary battery is avoided, the welding process window between the first current collector member and the housing is increased, and the production cost is reduced. Finally, the cover plate is hermetically installed on the opening of the second cylinder through a mechanical sealing process. While retaining the mechanical sealing process with mature technology, low cost and high efficiency, the process difficulties existing in the welding process of the first current collector member and the housing in the prior art are improved. Therefore, the present invention effectively overcomes some practical problems in the prior art and thus has high utilization value and practical significance. The above embodiments are only illustrative of the principles and effects of the present invention and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A secondary battery, characterized in that: include: A shell, one side of the shell is an open side, and the other side opposite to the secondary battery in the height direction is a closed side, and the shell includes a first cylinder and a second cylinder that are arranged in sections in the height direction of the secondary battery; One end of the first cylinder is provided with an end wall to form the closed side, and the other end of the first cylinder includes a first connecting section; One end of the second cylinder is provided with an opening to form the opening side, the other end of the second cylinder includes a second connecting section, the second connecting section is fixedly connected to the first connecting section, and a rolling groove recessed inward is arranged around the main body of the second cylinder; an electrode assembly is accommodated in the shell and arranged between the rolling groove and the end wall, and the electrode assembly includes a pole ear facing the opening; A cover plate, sealingly mounted on the opening; The current collecting member is disposed between the electrode assembly and the cover plate, and comprises a tab connection portion and a shell connection portion, wherein the tab connection portion is electrically connected to the tab, and the shell connection portion is electrically connected to the second cylinder.

2. The secondary battery according to claim 1, characterized in that: The first connecting section and the second connecting section at least partially overlap in a height direction of the secondary battery and form an overlapping area surrounding the housing.

3. The secondary battery according to claim 2, characterized in that: The length of the overlapping area along the height direction of the secondary battery is 0.1 to 5 mm.

4. The secondary battery according to claim 2, characterized in that: The second connecting section shrinks toward the inside of the second cylinder and has a diameter smaller than that of the first connecting section. The second connecting section is inserted into the inner side of the first connecting section and cooperates with the inner wall of the first connecting section to form the overlapping area.

5. The secondary battery according to claim 4, characterized in that: The second connecting section shrinks inwardly to form a first end surface, and the first end surface abuts against the first connecting section and is fixed by welding.

6. The secondary battery according to claim 2, characterized in that: The second connecting section protrudes outward from the second cylinder and has a diameter greater than that of the first connecting section. The first connecting section is inserted into the inner side of the second connecting section. The second connecting section cooperates with the outer wall of the first connecting section to form the overlapping area.

7. The secondary battery according to claim 6, characterized in that: The second connecting section is welded to the first connecting section in the overlapping area.

8. The secondary battery according to claim 2, characterized in that: The first connecting section shrinks toward the inside of the first cylinder and has a diameter smaller than that of the second connecting section. The first connecting section is inserted into the inner side of the second connecting section and cooperates with the inner wall of the second connecting section to form the overlapping area.

9. The secondary battery according to claim 8, characterized in that: The first connecting section shrinks inwardly to form a second end surface, and the second end surface abuts against the second connecting section and is fixed by welding.

10. The secondary battery according to claim 2, characterized in that: The first connecting section protrudes outward from the first cylinder and has a diameter greater than that of the second connecting section. The second connecting section is inserted into the inner side of the first connecting section. The first connecting section cooperates with the outer wall of the second connecting section to form the overlapping area.

11. The secondary battery according to claim 10, characterized in that: The first connecting section and the second connecting section are connected by welding in the overlapping area.

12. The secondary battery according to any one of claims 5, 7, 9 and 11, characterized in that: In the height direction of the secondary battery, a high temperature resistant protective layer is provided on the peripheral surface of the electrode assembly corresponding to the welding position of the first connecting segment and the second connecting segment.

13. The secondary battery according to claim 1, characterized in that: The second connecting segment is welded to the first connecting segment, and in the height direction of the secondary battery, a welding position of the second connecting segment and the first connecting segment corresponds to a height of the electrode tab and / or the current collecting member.

14. The secondary battery according to claim 1, characterized in that: The rolling groove forms a bulge inside the second cylinder, and along the height direction of the secondary battery, the distance from the side of the bulge close to the electrode assembly to the end of the second cylinder away from the opening is L, and L≤15mm.

15. The secondary battery according to claim 14, characterized in that: The current collecting component includes a central hole, the tab connection portion is disposed around the central hole, and the housing connection portion is disposed around the tab connection portion.

16. The secondary battery according to claim 15, characterized in that: The shell connection part and the pole tab connection part are an integral annular flat sheet, the pole tab connection part is welded to the pole tab, and the shell connection part is welded to a side of the protrusion facing the electrode assembly.

17. The secondary battery according to claim 15, characterized in that: The shell connection portion is welded to a side of the protrusion facing away from the electrode assembly, and the tab connection portion is recessed toward the electrode assembly side relative to the shell connection portion and is welded to the tab.

18. The secondary battery according to claim 14, characterized in that: The side of the second cylinder away from the electrode assembly includes a flange extending toward the center of the opening, and the edge of the cover plate is sealed and pressed between the flange and the protrusion.

19. The secondary battery according to claim 18, characterized in that: A groove is formed between the flange and the protrusion, and a sealing member is arranged between the cover plate and the groove.

20. The secondary battery according to claim 19, characterized in that: The sealing member surrounds and wraps the edge of the cover plate, and the flange presses the sealing member and the cover plate.

21. The secondary battery according to claim 1, characterized in that: The cover plate is provided with a discharge portion.

22. The secondary battery according to claim 21, characterized in that: The discharge portion includes a notch disposed on the cover plate, and an opening of the notch is close to the electrode assembly.

23. The secondary battery according to claim 1, characterized in that: The cover plate includes a plurality of reinforcing ribs, which are radially distributed around the axis of the cover plate and extend radially along the cover plate.

24. The secondary battery according to claim 1, characterized in that: The first cylinder and the second cylinder are both made of metal.

25. An electronic device, characterized in that: A battery pack is provided, the battery pack comprising the secondary battery according to any one of claims 1 to 24.

26. A method for manufacturing a secondary battery, characterized in that: The method comprises the following steps: Installing the electrode assembly into the first cylinder; Welding the current collecting member and the second cylinder to form an integrated component; Butt the integrated component with one end of the first cylinder, and weld and fix the second cylinder of the integrated component with the first cylinder; welding the current collecting member and the electrode tab of the electrode assembly facing the current collecting member; and The cover plate is sealingly mounted on the opening of the second cylinder which is away from the first cylinder.

27. The method for manufacturing a secondary battery according to claim 26, characterized in that: The second cylinder includes a rolling groove recessed toward the inside of the second cylinder, and the rolling groove forms a bulge inside the second cylinder; The current collecting member is welded to a side of the protrusion close to the electrode assembly to form the integrated component.

28. The method for manufacturing a secondary battery according to claim 27, characterized in that: The integrated component is nested with one end of the first cylinder to form an overlapping area; The second barrel is fixedly connected to the first barrel by irradiating laser in the overlapping area, the electrode assembly is sleeved in the cavity formed by the first barrel and the integrated component, and the current collecting member is in contact with the electrode assembly.

29. The method for manufacturing a secondary battery according to claim 27, characterized in that: Before the step of sealingly mounting the cover plate on the opening of the second cylinder, an electrolyte is injected into the opening.

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