Secondary battery and electronic device

Abstract

Provided are a secondary battery and an electronic device, the secondary battery comprising: a housing comprising a shell and a cover plate, one end of the shell forming an opening, the cover plate covering the opening and being connected to the shell, the cover plate being provided with an explosion-proof valve; the electrode assembly is accommodated in the shell, and the electrode assembly comprises a tab facing the cover plate; the current collecting component is in welded connection with the tabs; the flow collecting component is provided with an annular first weak part and a plurality of second weak parts, the projection of the anti-explosion valve in the axial direction of the flow collecting component is located in an area surrounded by the first weak part, the second weak parts are arranged around the center of the flow collecting component, and each second weak part longitudinally extends in the radial direction of the flow collecting component. The annular first weak part surrounds the second weak parts, and the strength of the second weak parts is larger than that of the annular first weak part. According to the technical scheme, at least the central area of the current collecting component can be effectively opened during pressure relief, and the pressure is sprayed out along with the anti-explosion valve, so that the safety performance of the battery is improved.

Description

Technical Field

[0001] This utility model relates to a secondary battery and an electronic device. Background Technology

[0002] In the field of new energy power batteries, secondary batteries generally include electrode components, a casing, and current collectors. The electrode components consist of positive and negative electrode plates, and a separator located between them. These positive and negative electrode plates and the separator are stacked and wound to form the electrode components, which are then encapsulated within the casing. Secondary batteries typically have current collectors at both ends of the electrode components within the casing. One end of the current collector is welded to the casing or end cap, and the other end is electrically connected to the tabs of the electrode components, thus achieving electrical connection between the casing and the electrode components.

[0003] Cell safety is the primary consideration for battery cell products, but in existing battery designs, the safety of batteries in situations such as thermal runaway still needs further improvement. Utility Model Content

[0004] In view of the problems existing in the related technologies, the purpose of this utility model is to provide a secondary battery and electronic device, so that at least the central area of ​​the current collector can be effectively opened when the pressure is released and ejected with the explosion-proof valve, so as to improve the safety performance of the battery.

[0005] To achieve the above objectives, this utility model provides a secondary battery, comprising: a casing, including a housing and a cover plate, one end of the housing forming an opening, the cover plate covering the opening and connected to the housing, and an explosion-proof valve provided on the cover plate; an electrode assembly, housed within the casing, the electrode assembly including tabs facing the cover plate; and a current collector, welded to the tabs; wherein the current collector has an annular first weak portion and multiple second weak portions, the projection of the explosion-proof valve on the axial direction of the current collector is located within the area surrounded by the first weak portion, the multiple second weak portions are arranged around the center of the current collector, each second weak portion extending longitudinally in the radial direction of the current collector, the annular first weak portion surrounding the multiple second weak portions, and the strength of the second weak portions being greater than the strength of the annular first weak portion.

[0006] In some embodiments, the current collector further includes a through hole disposed around the periphery of the annular first weak portion, the through hole penetrating the current collector in the thickness direction.

[0007] In some embodiments, the edge of the current collector is provided with a plurality of protrusions connected to the housing, wherein a through hole is provided on the current collector between two protrusions.

[0008] In some embodiments, the through hole has two opposing arc surfaces that protrude away from the center, wherein the radius of curvature of the arc surface away from the center is smaller than the radius of curvature of the other arc surface near the center, and the two ends of one arc surface are connected to the two ends of the other arc surface.

[0009] In some embodiments, the first weak portion of the annular structure includes a plurality of perforated holes spaced apart along an annular path, and a connecting portion located between adjacent perforated holes. The current collection member within the first weak portion of the annular structure is connected to a current collection member outside the first weak portion of the annular structure through the connecting portion.

[0010] In some embodiments, the second weak portion includes a groove extending radially.

[0011] In some embodiments, the second weak portion includes a perforation extending radially.

[0012] In some embodiments, a plurality of second weak sections are arranged at equal intervals around the center of the current collection member.

[0013] In some embodiments, the welding area formed by welding the current collector to the electrode tab is located in the area surrounded by the first weak part. The welding area includes a head portion near the center and a tail portion away from the center. The head portion is welded to a first number of electrode tabs, and the tail portion is welded to a second number of electrode tabs. The first number of layers is less than the second number of layers.

[0014] Embodiments of this application also provide an electronic device including any of the above-described secondary batteries.

[0015] The technical solution of this application, by setting a first weak part and a second weak part, allows the first weak part to break preferentially during battery depressurization, enabling the area surrounded by the first weak part to open smoothly. The second weak part allows the area surrounded by the first weak part to deform and contract in a similar umbrella shape. The area of ​​the current collector surrounded by the first weak part can then fly out with the material from the opening of the explosion-proof valve, reducing the current collector's obstruction of the depressurization path, improving the depressurization effect, and reducing the risk of casing damage and explosion. This enhances battery safety performance. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A perspective view of a secondary battery according to an embodiment of this application is shown.

[0018] Figure 2 A front view of a secondary battery according to an embodiment of this application is shown.

[0019] Figure 3 A secondary battery according to an embodiment of this application is shown. Figure 2 A cross-sectional view of line X1-X1 in the diagram.

[0020] Figures 4 to 9 A top view schematic diagram of a current collection component according to several different embodiments of this application is shown.

[0021] Figure 10 A schematic diagram is shown when the electronic device according to an embodiment of this application is a vehicle. Detailed Implementation

[0022] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0023] Embodiments of this application will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions are indicated by similar reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative and diagrammatic in nature and are intended to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.

[0024] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate minor variations. When used in conjunction with an event or situation, these terms may refer to examples in which the event or situation occurred precisely or in examples in which the event or situation occurred very approximately.

[0025] In this specification, unless otherwise specified or limited, relative terms such as “central,” “longitudinal,” “lateral,” “front,” “rear,” “right,” “left,” “inner,” “outer,” “lower,” “higher,” “horizontal,” “vertical,” “above,” “below,” “above,” “below,” “top,” “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to the directions described in the discussion or depicted in the accompanying drawings. These relative terms are used for descriptive convenience only and do not require that this application be constructed or operated in a particular orientation.

[0026] For ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0027] Safety is the primary consideration for battery products, especially under extreme conditions where ensuring human safety is paramount. Generally, a secondary battery should be able to open its explosion-proof valve smoothly during thermal runaway, releasing pressure and venting gas without causing an explosion, ensuring the battery casing remains intact, and preventing the splashing of hard materials that could cause injury. In current designs, the explosion-proof valve is typically located at the bottom of the battery, where materials will be ejected downwards during thermal runaway. However, when the explosion-proof valve opens, incomplete combustion, a loose or broken current collector, and gravity can block the valve opening, obstructing venting. In severe cases, this can lead to battery casing rupture, ejected terminals, or even an explosion, compromising battery safety performance.

[0028] Figure 1 A perspective view of a secondary battery 100 according to an embodiment of this application is shown. Figure 2 A front view of a secondary battery 100 according to an embodiment of this application is shown. Figure 3 A secondary battery 100 according to an embodiment of this application is shown. Figure 2 The cross-sectional view is shown along line X1-X1. In this embodiment, a cylindrical battery is shown as an example for the secondary battery 100. In some embodiments, the secondary battery 100 may be a 4680 cylindrical battery (46 mm in diameter, 80 mm in height), a 4695 cylindrical battery (46 mm in diameter, 95 mm in height), or a 46120 cylindrical battery (46 mm in diameter, 120 mm in height). Here, the diameter refers to the outer diameter of the casing.

[0029] See also Figures 1 to 3 The secondary battery 100 may include a cylindrical battery. The secondary battery 100 includes a casing, which comprises a housing 110 and a cover plate 140. The housing 110 may specifically include an end wall 111 and a side wall 112 surrounding the end wall 111. As long as a stable sealing and electrical connection can be formed, the connection between the end wall 111 and the side wall 112 can be achieved in various ways, such as integral stamping, integral casting, or separate welding. The side wall 112 may be cylindrical or follow any other closed-loop contour that matches the end wall 111. In this embodiment, the outer edge of the end wall 111 is circular, and the side wall 112 is cylindrical and surrounds the outer edge of the end wall 111.

[0030] Specifically, the diameter of the housing 110 can be determined according to the specific size of the electrode assembly 130, such as 18mm, 21mm, 46mm, etc. The housing 110 and the cover plate 140 can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the housing 110 and the cover plate 140 from rusting during long-term use, a layer of anti-rust material such as metallic nickel can be plated on the surface of the housing 110 and the cover plate 140.

[0031] An opening 113 is formed at one end of the side wall 112 opposite to the end wall 111, and a cover plate 140 is closed over the opening 113. The electrode assembly 130 is housed within the space defined by the housing 110 and the cover plate 140, and is used to house the electrode assembly 130, electrolyte, and other battery-essential components.

[0032] The electrode assembly 130 can be mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material, the positive active material being coated on the surface of the positive current collector; the positive current collector includes a coated area with active material and an uncoated area without active material, the uncoated area being wound to form the positive electrode tab of the electrode assembly 130. The negative electrode sheet includes a negative current collector and a negative active material, the negative active material being coated on the surface of the negative current collector; the negative current collector includes a coated area with active material and an uncoated area without active material, the uncoated area being wound to form the negative electrode tab of the electrode assembly 130. Taking a lithium-ion secondary battery as an example, the material of the positive current collector can be aluminum, and the positive active material layer includes the positive active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode current collector can be made of copper, and the negative electrode active material layer includes a negative electrode active material, which can be carbon or silicon, etc. The separator can be made of PP (polypropylene) or PE (polyethylene), etc. To protect and insulate the electrode assembly 130, an insulating film can be wrapped around the outside of the electrode assembly 130. The insulating film can be synthesized from PP, PE, PET (polyethylene terephthalate), PVC (polyvinyl chloride), or other polymer materials.

[0033] Electrode assembly 130 may include a first tab 131 facing opening 113 and a second tab 132 facing end wall 111. Terminal 120 may pass through end wall 111 and be insulated from end wall 111. Electrical insulation between terminal 120 and end wall 111 of housing 110 can be achieved in various ways. For example, insulation can be achieved by placing an insulating washer between terminal 120 and end wall 111. Terminal 120 may be made of a conductive metallic material. For example, the material of terminal 120 may be aluminum (Al).

[0034] In this embodiment, the first tab 131 is a negative tab, and the opening 113 side of the housing 110 is electrically connected to the first tab 131, thus carrying a negative charge. The second tab 132 can be a positive tab, and the terminal 120 is electrically connected to the second tab 132, carrying a positive charge. A current collector 150 is disposed at the end of the electrode assembly 130 facing the opening 113, and the first tab 131 can be connected to the housing 110 through the current collector 150. The current collector 150 can be welded to the first tab 131. The second tab 132 can be electrically connected to the terminal 120 through the current collector 160. In embodiments where the secondary battery is a cylindrical battery, the electrode assembly 130 can have a central through hole 133. The central through hole 133 can maintain smoother communication between the spaces at both ends of the electrode assembly 130, and can be used as an exhaust path for the gas generated by the electrode assembly 130 during operation.

[0035] The materials of current collectors 150 and 160 can be selected according to the polarity of the tabs they are connected to. Current collectors 150 and 160 can be made of different metals. For example, if current collector 160 is connected to the positive tab, it can be made of aluminum, while current collector 150 connected to the negative tab can be made of copper. The current collectors can be called current collector disks, and current collectors 150 and 160 can be called the negative current collector disk and the positive current collector disk, respectively.

[0036] An explosion-proof valve 145 may also be installed on the cover plate 140. The explosion-proof valve 145 is used to at least partially open when the internal air pressure of the housing 110 reaches a certain level, so as to release the pressure inside the housing 110. The type of explosion-proof valve 145 is not limited. Figure 3 In the illustrated embodiment, the explosion-proof valve 145 includes grooves on the cover plate 140. The explosion-proof valve 145 is located on the side of the cover plate 140 facing the electrode assembly 130. The explosion-proof valve 145 can be annular. It should be noted that the annular structure is not limited to the grooves being circular or elliptical. Of course, in other embodiments, the grooves can also be other structures, as long as they can open when the pressure exceeds a set threshold. The explosion-proof valve 145, constructed with grooves, is located in a weaker area of ​​the cover plate 140. When the air pressure inside the housing 110 exceeds a certain threshold, the weaker groove will rupture, and the air pressure inside the housing 110 can be released from the rupture, thereby preventing the secondary battery from exploding from the housing.

[0037] In this embodiment, the cover plate 140 and the side wall 112 are not integral. In other embodiments, the positions of the cover plate 140 and the end wall 111 can be interchanged, such that the cover plate 140 and the side wall 112 are integral. The cover plate 140 is located on the positive electrode side of the electrode assembly and is used for pressure relief from the positive electrode side.

[0038] Figure 4 This is a top view of a current collection member 150 according to an embodiment of this application. See also... Figure 4 As shown, the current collector 150 has an annular first weak portion 210. By providing the annular first weak portion 210, when the battery is depressurized, the first weak portion 210 breaks, and the area of ​​the current collector 150 surrounded by the first weak portion 210 can fly out from the opening of the explosion-proof valve 145, thus reducing the obstruction of the depressurization path by the current collector 150.

[0039] As described above, the current collector 150 is welded (e.g., by laser penetration welding) to the corresponding tab of the electrode assembly (e.g., the negative tab), thus the current collector 150 can have a welded area formed by welding. In the axial direction of the current collector 150, the explosion-proof valve 145 has a projection 145' on the current collector 150. If the area surrounded by the first weak portion 210 is smaller than the area of ​​the projection 145' of the explosion-proof valve 145, the area surrounded by the first weak portion 210 is too small to form a sufficiently large welded area to weld with the tab, resulting in failure to meet the overcurrent requirement. Therefore, according to an embodiment of this application, the projection 145' of the explosion-proof valve 145 is located within the area surrounded by the first weak portion 210. That is, the area surrounded by the first weak portion 210 is larger than the area surrounded by the explosion-proof valve 145. Thus, the area surrounded by the first weak portion 210 can provide a sufficiently large welded area to weld with the tab.

[0040] The flow collector 150 also has multiple second weak points 220. Figure 4 Eight second weak points 220 are shown as an example. Multiple second weak points 220 are arranged around the center 150c of the manifold 150, each second weak point 220 extending longitudinally in the radial direction of the manifold 150. A first weak point 210 surrounds the multiple second weak points 220. By providing multiple second weak points 220, the manifold 150 surrounded by the first weak point 210 can be ejected from the opening of the explosion-proof valve 145. During depressurization, the multiple second weak points 220 arranged around the center 150c can provide a deformation contraction area, allowing the area surrounded by the first weak point 210 to deform and contract in an umbrella-like shape, thereby allowing the portion surrounded by the first weak point 210 to be ejected from the opening of the explosion-proof valve 145.

[0041] Furthermore, the strength of the second weak portion 220 should be greater than the strength of the annular first weak portion 210. This ensures that during pressure relief, the first weak portion 210 will fracture more easily than the second weak portion 220, thus preventing the problem of the first weak portion 210 failing to fracture when the second weak portion 220 fractures, thus preventing the portion surrounded by the first weak portion 210 from flying out. This ensures that the portion surrounded by the first weak portion 210 can fly out from the opening of the explosion-proof valve 145.

[0042] The above technical solution, by setting the first weak part 210 and the second weak part 220 as configured above, allows the first weak part 210 to break first during battery depressurization, enabling the area surrounded by the first weak part 210 to open smoothly. The second weak part 220 allows the area surrounded by the first weak part 210 to deform and contract in an umbrella-like shape. The area of ​​the current collector 150 surrounded by the first weak part 210 can then fly out with the material from the opening of the explosion-proof valve 145, reducing the obstruction of the depressurization path by the current collector 150, improving the depressurization effect, and reducing the risk of casing damage and explosion. This enhances battery safety performance.

[0043] See also Figure 4 As shown, the annular first weak portion 210 may include a plurality of perforated holes 212 spaced apart along an annular path, and connecting portions 214 located between adjacent perforated holes 212. A current-collecting member 150 inside the first weak portion 210 is connected to a current-collecting member 150 outside the first weak portion 210 via the connecting portions 214. Forming the first weak portion 210 through the perforated holes 212 is less technically demanding and provides suitable strength to rupture upon pressure relief.

[0044] In some embodiments, such as in a 4680 cylindrical battery, the diameter d of the region surrounded by the first weak portion 210 can range from 30mm to 35mm. In some embodiments, the width of the perforated hole 212 (radially of the annular first weak portion 210) can be, for example, 0.5mm. The length of the connecting portion 214 (circumferentially of the annular first weak portion 210) can range from 0.5mm to 1mm.

[0045] exist Figure 4 In the illustrated embodiment, the second weak portion 220 may include a plurality of perforated holes 222 and a connecting portion 224 located between adjacent perforated holes 222. Forming the second weak portion 220 through a plurality of perforated holes 222 is less technically difficult and can provide suitable strength to undergo umbrella-shaped deformation and contraction during depressurization.

[0046] exist Figure 4 In the illustrated embodiment, there are eight second weak points 220. Each second weak point 220 extends radially along the manifold 150. Each second weak point 220 may extend from the center 150c to the vicinity of the first weak point 210. In some embodiments, the second weak points 220 are arranged at equal intervals around the center 150c. Such a uniform arrangement of multiple second weak points 220 is more conducive to umbrella-shaped deformation and contraction during depressurization, ensuring that the portion surrounded by the first weak point 210 can fly out from the opening of the explosion-proof valve 145.

[0047] In some embodiments, the width of the perforated hole 222 (radially perpendicular to the current collecting member 150) can be, for example, 0.5 mm. The length of the connecting portion 224 (radially of the current collecting member 150) can be 0.5 mm to 1 mm. In some embodiments, the length of the connecting portion 224 of the second weak portion 220 is greater than the length of the connecting portion 214 of the first weak portion 210 to ensure that the strength of the second weak portion 220 is greater than the strength of the annular first weak portion 210. In this embodiment, the length of the perforated hole 222 can be less than the length of the perforated hole 212 to ensure that the strength of the second weak portion 220 is greater than the strength of the annular first weak portion 210.

[0048] The current collection member 150 may further include at least one through hole 230 disposed around the periphery of the first weak portion 210. Figure 4 In the illustrated embodiment, four through holes 230 are shown as an example. The through holes 230 penetrate the current collector 150 in the thickness direction. The through holes 230 can serve as injection holes for injecting electrolyte. The through holes 230 are located around the first weak point 210, which avoids overlap with the welding areas of the current collector 150 and the electrode tab, ensuring a sufficiently large welding area.

[0049] By providing a through hole 230 around the first weak point 210, the existing central injection hole design can be eliminated, allowing for multi-point injection during battery filling and improving injection efficiency. Simultaneously, since there is no need to create an injection hole in the central region of the current collector 150, the central region of the current collector 150 experiences more uniform force and a larger force-bearing surface at the moment the thermal runaway explosion-proof valve opens. This further ensures that the area of ​​the current collector 150 surrounded by the first weak point 210 can rupture and discharge, enhancing battery safety performance.

[0050] Specifically, the flow collector 150 may include a main body 152 and a plurality of protrusions 154. Figure 4 Four or more protrusions 154 are shown as an example. The main body 152 may have a circular profile. The protrusions 154 are connected to the edges of the main body 152 and are used to connect to the sidewalls 112 of the housing 110. The protrusions 154 may be arranged at equal intervals along the edges of the main body 152. In some embodiments, each through hole 230 is provided on the flow collector 150 between two protrusions 154. That is, the through hole 230 does not overlap with the protrusion 154 along the radial direction of the flow collector 150. Providing the through hole 230 between two protrusions 154 makes the forming process of the through hole 230 easier to operate.

[0051] In some embodiments, the through hole 230 has two opposing arcuate surfaces 230a and 230b. Both arcuate surfaces 230a and 230b protrude away from the center 150c. Arcuate surface 230a is further away from the center 150c, while arcuate surface 230b is closer to the center 150c. The radius of curvature of arcuate surface 230a is smaller than that of arcuate surface 230b, and the two ends of arcuate surface 230a are respectively connected to the two ends of arcuate surface 230b. Thus, the through hole 230 can have a crescent-shaped top view profile. This shape of the through hole 230 is more suitable for fitting with the annular shape of the first weak portion 210 and provides a larger injection hole size.

[0052] also, Figure 4 A welded region 190 formed by welding the current collector 150 to an electrode tab (e.g., a negative electrode tab) is also shown. For simplicity, only one welded region 190 is shown as an example. The welded region 190 is located within the area surrounded by the first weak portion 210. The welded region 190 may include a head portion 191 adjacent to the center 150c and a tail portion 192 away from the center 150c. In some embodiments, the maximum width of the tail portion 192 is greater than the maximum width of the head portion 191. In this embodiment, the welded region 190 has a teardrop-like shape. This shape of the welded region 190 facilitates easier breakage of the welded region 190 near the center 150c during thermal runaway, allowing the current collector 150 and the electrode assembly to detach after the explosion-proof valve opens, thereby ensuring smooth pressure relief.

[0053] In some embodiments, the length of the first portion 191 (radial along the manifold 150) may account for 10%-50% of the total length of the welded region 190. In some embodiments, the weld strength of the first portion 191 is less than the weld strength of the tail portion 192, such that the first portion 191 is welded to a first number of electrode tabs, and the tail portion 192 is welded to a second number of electrode tabs, the first number being less than the second number. In such embodiments, low-power welding (e.g., 800W-1200W) can be used to form the first portion 191 of the welded region 190, and conventional power welding (e.g., 1200W-1600W) can be used to form the tail portion 192. This design of lower weld strength in the inner ring first portion 191 facilitates the preferential disconnection of the inner ring welded region 190 in the event of thermal runaway, allowing the manifold 150 and electrode assembly to detach after the explosion-proof valve opens, thereby ensuring smooth pressure relief.

[0054] Figure 5 This is a top view of a current collection component according to another embodiment of this application. Figure 5 The current collector shown can be compared with the above reference in several aspects. Figure 4 The described current collector components are similar; the following mainly describes... Figure 5 The differences in the current collection components shown are illustrated. See also... Figure 5 As shown, in this embodiment, the second weak point 220 is a groove extending radially along the current collector 150. Multiple second weak points 220 may intersect at the center 150c. Forming the second weak point 220 by grooves can reduce the manufacturing difficulty and provide suitable strength to undergo umbrella-shaped deformation and contraction during depressurization.

[0055] In some embodiments, the width of the notch in the second weak portion 220 can be 0.5 mm. Since the first weak portion 210 is formed by a plurality of hollow holes 212, while the second weak portion 220 is formed by notches, it can be ensured that the strength of the second weak portion 220 is greater than the strength of the annular first weak portion 210, so as to ensure smooth pressure relief.

[0056] Figure 6 This is a top view of a current collection component according to another embodiment of this application. Figure 6 The current collector shown can be compared with the above reference in several aspects. Figure 4 and Figure 5 The described current collector components are similar; the following mainly describes... Figure 6 The differences in the current collection components shown are illustrated. See also... Figure 6 As shown, in this embodiment, the multiple second weak points 220 are grooves. The groove width can be, for example, 0.5 mm. The number of connecting portions 214 of the first weak point 210 is the same as the number of second weak points 220. The number of second weak points 220 and connecting portions 214 are both 8. In this embodiment, the length of the connecting portion 214 can range from 0.5 mm to 1 mm.

[0057] The end of each second weak portion 220 furthest from the center 150c can be connected to the corresponding connecting portion 214. A perforation 212 is provided in the region between two adjacent second weak portions 220. The perforation 212 extends continuously between two adjacent second weak portions 220. In this embodiment, the width of the perforation 212 can be, for example, 0.5 mm. This configuration of the first weak portion 210 makes its strength sufficiently small; and the second weak portion 220 formed by the notch is more likely to ensure that its strength is greater than that of the first weak portion 210, thus ensuring smooth pressure relief.

[0058] Figure 7 This is a top view of a current collection component according to another embodiment of this application. Figure 7 The current collector shown can be compared with the above reference in several aspects. Figures 4 to 6 The described current collector components are similar; the following mainly describes... Figure 7 The differences in the current collection components shown are illustrated. See also... Figure 7As shown, in this embodiment, the number of connecting portions 214 of the first weak portion 210 is further reduced. The number of connecting portions 214 is four. In this embodiment, the length of the connecting portion 214 can range from 0.5mm to 1mm.

[0059] Each second weak point 220 is a single perforated hole 222 extending radially along the current collecting member 150. Each perforated hole 222 is spaced from the center 150c. The number of second weak points 220 can be greater than the number of connecting points 214. The number of second weak points 220 can be eight. In this embodiment, the length of each perforated hole 222 can range from 10mm to 12mm. The widths of the perforated holes 212 and 222 can be the same, for example, both 0.5mm.

[0060] Since the number of connecting parts 214 is further reduced, the strength of the first weak part 210 can be further reduced. Therefore, it is permissible to form each second weak part 220 by a single hollow hole 222, while still ensuring that the strength of the second weak part 220 is greater than that of the first weak part 210, thereby ensuring smooth pressure relief.

[0061] Figure 8 This is a top view of a current collection component according to another embodiment of this application. Figure 8 The current collector shown can be compared with the above reference in several aspects. Figure 4 The described current collector components are similar; the following mainly describes... Figure 8 The differences in the flow collector components shown are illustrated. Figure 8 In the illustrated embodiment, the second weak portion 220 includes a plurality of perforations 222 and a connecting portion 224 located between adjacent perforations 222. The number of second weak portions 220 can be four. In other embodiments, the number of second weak portions 220 can also be other.

[0062] Figure 9 This is a top view of a current collection component according to another embodiment of this application. Figure 9 The current collector shown can be compared with the above reference in several aspects. Figures 4 to 8 The described current collector components are similar; the following mainly describes... Figure 9 The differences in the current collection components shown are illustrated. See also... Figure 9As shown, in this embodiment, both the first weak portion 210 and the second weak portion 220 are grooves. One end of the second weak portion 220, away from the center 150c, can be connected to the first weak portion 210. In some embodiments, the groove widths of the first weak portion 210 and the second weak portion 220 are the same. In some embodiments, the groove depth of the second weak portion 220 may be less than the groove depth of the first weak portion 210, so that the strength of the second weak portion 220 is greater than the strength of the first weak portion 210. In some embodiments, the groove depth of the second weak portion 220 is 50% of the groove depth of the first weak portion 210. In some embodiments, the groove depth of the first weak portion 210 is 30%-70% of the thickness of the current collector 150.

[0063] See Figure 10 The embodiments of this application also provide an electronic device 1000. For ease of explanation, the following embodiments will use a vehicle as an example to illustrate the electronic device 1000. Figure 10 A schematic diagram is shown when the electronic device according to an embodiment of this application is a vehicle.

[0064] A battery pack 1002 may be installed inside the vehicle, and the battery pack 1002 may be located at the bottom, front, or rear of the vehicle body 1001. The battery pack 1002 may include the secondary batteries described above. The battery pack 1002 can be used to power the vehicle; for example, the battery pack 1002 can serve as the vehicle's operating power source. The working part of the electronic device 1000 is electrically connected to the battery pack 1002 to obtain electrical power support. The vehicle may be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles may be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc., but are not limited thereto. The working part is the vehicle body 1001, and the battery pack 1002 is located at the bottom of the vehicle body 1001, providing electrical power support for the vehicle's operation or the operation of electrical components within the vehicle. However, in some other embodiments, the electronic device 1000 may also be a mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working unit can obtain electrical energy from the battery pack 1002 and perform corresponding work, such as the fan blade rotation unit of a fan, the vacuuming unit of a vacuum cleaner, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of this application do not impose special limitations on the above-mentioned electronic device 1000.

[0065] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A secondary battery characterized by comprising: The secondary battery comprises: a housing including a casing and a cover plate, one end of the casing forming an opening, the cover plate covering the opening and being connected to the casing, the cover plate being provided with an explosion-proof valve; an electrode assembly accommodated in the housing, the electrode assembly including a tab facing the cover plate; a current collecting member welded to the tab; wherein the current collecting member has a first annular weak portion and a plurality of second weak portions, a projection of the explosion-proof valve in an axial direction of the current collecting member being located in an area surrounded by the first weak portion, the plurality of second weak portions being arranged around the center of the current collecting member, each of the second weak portions extending longitudinally in a radial direction of the current collecting member, the first annular weak portion surrounding the plurality of second weak portions, and the second weak portions having a strength greater than that of the first annular weak portion.

2. The secondary battery according to claim 1, wherein the current collecting member further comprises a through hole arranged at a periphery of the first annular weak portion, the through hole penetrating the current collecting member in a thickness direction of the current collecting member.

3. The secondary battery according to claim 2, wherein an edge of the current collecting member is provided with a plurality of protrusions connected to the casing, and the through hole is arranged on the current collecting member between two of the protrusions.

4. The secondary battery according to claim 2, wherein the through hole has two opposite arc surfaces protruding away from the center, a curvature radius of one of the arc surfaces away from the center being smaller than that of the other arc surface adjacent to the center, and two ends of the one arc surface being connected to two ends of the other arc surface.

5. The secondary battery according to claim 1, wherein the first annular weak portion comprises a plurality of hollow holes spaced apart from each other along an annular path, and a connecting portion between adjacent hollow holes, the current collecting member in the first annular weak portion being connected to the current collecting member outside the first annular weak portion through the connecting portion.

6. The secondary battery according to claim 1, wherein the second weak portion comprises a score extending along the radial direction.

7. The secondary battery according to claim 1, wherein the second weak portion comprises a hollow hole extending along the radial direction.

8. The secondary battery according to claim 1, wherein the plurality of second weak portions are arranged at equal intervals around the center of the current collecting member.

9. The secondary battery according to claim 1, wherein a welding area of the current collecting member and the tab is located in the area surrounded by the first weak portion, the welding area including a leading portion adjacent to the center and a trailing portion away from the center, the leading portion being welded to a first number of tabs, the trailing portion being welded to a second number of tabs, the first number being less than the second number.

10. An electronic device, comprising: The secondary battery as claimed in any one of claims 1 to 9.

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