Secondary battery and battery pack

Abstract

The utility model provides a secondary battery and a battery pack, the secondary battery comprises: a housing comprising a shell and a cover plate, one end of the shell is provided with an opening, the cover plate covers the opening and is connected to the shell, and the cover plate is 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 tab, the current collecting component comprises a plurality of first through grooves penetrating through the current collecting component in the thickness direction of the current collecting component, the first through grooves are formed around the center of the current collecting component, and each first through groove longitudinally extends from the edge of the current collecting component in the radial direction of the current collecting component; the end, close to the center, of each first through groove is located in the projection area of the anti-explosion valve in the axial direction of the flow collecting component. According to the technical scheme, at least the exhaust efficiency under the thermal runaway condition can be improved.

Description

Technical Field

[0001] This utility model relates to a secondary battery and a battery pack. 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 sheets, and a separator located between them. These positive and negative electrode sheets 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 a cover plate, 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] Battery safety is the primary concern for battery cell products, but existing battery designs still need further improvement in terms of safety under conditions such as thermal runaway. 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 battery pack, so as to improve the exhaust efficiency under thermal runaway conditions.

[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 disposed 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 includes a plurality of first through slots penetrating the current collector in its thickness direction, the plurality of first through slots being arranged around the center of the current collector, each first through slot extending radially from the edge of the current collector, and the end of each first through slot near the center located within the projection area of ​​the explosion-proof valve in the axial direction of the current collector.

[0006] In some embodiments, the flow collector includes a plurality of segments separated by a plurality of first through slots, wherein at the arc-shaped outer edge of the segment away from the center, the corner of the segment adjacent to the corresponding first through slot is rounded.

[0007] In some embodiments, the current collecting member further includes a plurality of second through grooves extending through the current collecting member in its thickness direction, wherein each second through groove is connected to the end of a corresponding first through groove, and the longitudinal extension direction of each second through groove is perpendicular to the longitudinal extension direction of the corresponding first through groove.

[0008] In some embodiments, the flow collector includes a plurality of segments separated by a plurality of first through slots, and the surface of the segments facing the cover plate is provided with grooves that extend longitudinally from the outer edge of the segments away from the center toward the center.

[0009] In some embodiments, the flow collector includes a plurality of segments separated by a plurality of first through slots, and a central portion connected to the plurality of segments, the central portion having a boss disposed around the center and a buffer portion disposed around the boss.

[0010] In some embodiments, each segment has a welding area formed by welding it to the tab, wherein a first end of the welding area is adjacent to the buffer portion, and the width of the welding area increases in a direction radially away from the first end of the welding area from the buffer portion.

[0011] In some embodiments, each segment has multiple weld lines formed by welding it to the tab, each weld line having a sinusoidal shape that oscillates along a corresponding reference line, wherein, in the direction away from the center, the interval between the reference lines corresponding to each pair of adjacent weld lines on each segment gradually increases, and in the direction perpendicular to the reference line, the difference between the peaks and troughs of the sinusoidal weld line is 0.5mm-2mm.

[0012] In some embodiments, each segment has multiple weld lines formed by welding it to the tabs, each weld line including a head portion near the center and a tail portion away from the center, the head portion being welded to a first number of tabs, and the tail portion being welded to a second number of tabs, the first number of layers being less than the second number of layers.

[0013] In some embodiments, the central portion of the current collector is welded to the cover plate, and the cover plate is connected to the housing so that the housing and the tab have the same polarity.

[0014] Embodiments of this application also provide a battery pack, including the aforementioned secondary battery.

[0015] Embodiments of this application also provide an electronic device including the battery pack described above.

[0016] The technical solution described in this application, by adding a first through groove to the current collector, allows the current collector to more easily form an umbrella-like shape during thermal runaway, facilitating its detachment from the explosion-proof valve opening. This reduces the risk of the current collector blocking the explosion-proof valve opening, improves the venting efficiency of the battery under thermal runaway conditions, and enhances the battery's safety performance. Furthermore, this current collector has a simple structure, is easy to manufacture, and has low cost, making it suitable for mass production. Attached Figure Description

[0017] 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.

[0018] Figure 1 A perspective view of a secondary battery according to an embodiment of this application is shown.

[0019] Figure 2 A front view of a secondary battery according to an embodiment of this application is shown.

[0020] 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.

[0021] Figure 4A and Figure 4B These are respectively an isometric view and a top view of a current collection component according to an embodiment of this application.

[0022] Figures 5 to 8 A top view schematic diagram of a current collection component according to several different embodiments of this application is shown.

[0023] Figure 9 A schematic diagram is shown when the electronic device according to an embodiment of this application is a vehicle. Detailed Implementation

[0024] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] Rechargeable batteries are widely used in various industries. With the rapid development of the electric vehicle industry, cylindrical batteries, due to their high energy density, excellent thermal management, mature manufacturing processes, and good consistency, have gradually become an important development direction in the power battery field. Battery safety characteristics remain a key focus of the industry, especially under extreme thermal runaway conditions (such as overcharging, over-discharging, high temperatures, or mechanical damage). In such cases, a chain reaction can occur inside the battery (e.g., lithium-ion batteries), potentially leading to a rapid increase in internal temperature, the generation of large amounts of gas, and even fire or explosion. Therefore, battery design must be able to rapidly release internal pressure during thermal runaway, maintain the integrity of the casing, and prevent secondary splashing of materials that could cause serious injury to the human body.

[0030] The safety requirements of cylindrical battery cells present greater challenges to the strength of mechanical components and the sealing performance of the casing. In some cylindrical battery cell designs, laser sealing technology uses laser welding to weld the casing and cover plate together. The current collector (also known as the current collector plate) is attached to the cover plate and connected by laser welding. In the event of thermal runaway, the current collector detaches along with the cover plate, achieving material release and venting. This solution offers good sealing performance, high strength, and high structural controllability, and is considered one of the main packaging methods currently available.

[0031] However, in this design, due to overcurrent requirements, the diameter of the current collector is usually larger than the opening diameter of the explosion-proof valve. During thermal runaway, the electrode assembly impacts downwards, and the current collector is easily squeezed by the electrode assembly, blocking the opening of the explosion-proof valve and making it difficult to detach smoothly with the cover plate, resulting in poor venting. On the other hand, on the negative electrode side, the solder joints between the current collector and the electrode assembly are not easily broken during thermal runaway, also preventing the current collector from detaching smoothly and affecting the venting effect. These problems severely restrict the safety performance of cylindrical batteries, and a new design is urgently needed to optimize the current collector structure and improve venting efficiency under thermal runaway conditions.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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).

[0038] In this embodiment, the first tab 131 is a negative tab. The opening 113 side of the housing 110 can be electrically connected to the first tab 131 through the cover plate 140, 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. The current collector 150 is disposed at the end of the electrode assembly 130 facing the opening 113, and the first tab 131 can be welded to the current collector 150, and the current collector 150 can be welded to the cover plate 140. 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.

[0039] 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.

[0040] 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 explosion-proof valve 145 will rupture, forming an opening on the cover plate. At this time, the air pressure inside the housing 110 can be discharged through the opening, thereby preventing the secondary battery from exploding from the housing.

[0041] Figure 4A This is an isometric view of a current collection member 150 according to an embodiment of this application. Figure 4B This is a top view of a current collection member 150 according to an embodiment of this application. Figure 4A and Figure 4BThe surface of the flow collector 150 shown is the side facing the cover plate 140. (Combined) Figure 4A and Figure 4B As shown, the current collecting member 150 includes a central hole 150v. The center of the central hole 150v is the center of the current collecting member 150. It should be understood that in some other embodiments, the current collecting member 150 may not have a central hole 150v. A plurality of first through slots 201 extend through the current collecting member 150 in the thickness direction. The plurality of first through slots 201 are arranged around the central hole 150v of the current collecting member 150. In some other embodiments where the current collecting member 150 does not have a central hole 150v, the plurality of first through slots 201 may be arranged around the center of the current collecting member 150. Each first through slot 201 extends radially from the edge of the current collecting member 150. By providing a plurality of first through slots 201, the current collecting member 150 includes a plurality of segments 152 separated by the plurality of first through slots 201. The plurality of segments 152 are connected to the central portion 154 of the current collecting member 150. This gives the current collection component 150 a petal-like top view structure.

[0042] The end 201a of each first through groove 201 is adjacent to the center of the manifold 150. In the axial direction of the manifold 150, the explosion-proof valve 145 of the cover plate 140 has an annular projection area 145' on the manifold 150. The end 201a of the first through groove 201 is located within the projection area 145'.

[0043] The above-described technical solution, by adding a first through groove 201 to the current collector 150, allows the current collector 150 to more easily form an umbrella-like shape during thermal runaway, facilitating its detachment from the explosion-proof valve opening. This reduces the risk of the current collector blocking the explosion-proof valve opening, improves the venting efficiency of the battery under thermal runaway conditions, and enhances the battery's safety performance. Furthermore, the current collector 150 has a simple structure, is easy to manufacture, and has low cost, making it suitable for mass production.

[0044] In some embodiments, the first through grooves 201 are uniformly distributed around the center of the flow collecting member 150. In this embodiment, the first through grooves 201 are uniformly distributed around the central hole 150v. In some embodiments, the number of first through grooves 201 can be three to six, and correspondingly, the number of dividing portions 152 can be three to six. Figure 4A and Figure 4B Four first through slots 201 are shown as examples.

[0045] In some embodiments, the central portion 154 of the manifold 150 is welded to the cover plate 140. Figure 4A and Figure 4BIn the illustrated embodiment, the central portion 154 has a boss 156 surrounding the central hole 150v of the manifold 150 and protruding toward the cover plate 140. The boss 156 is welded to the cover plate 140, specifically to the cover plate 140 surrounding the explosion-proof valve 145. In some other embodiments where the manifold 150 does not have a central hole 150v, the boss 156 may be positioned around the center of the manifold 150. In other embodiments, the central portion 154 of the manifold 150 may be welded to the cover plate 140 using other applicable structures. Furthermore, the cover plate 140 is connected to the housing 110. For example, the cover plate 140 may be welded to the sidewall 112 at the opening 113 of the housing 110. The segment 152 of the manifold 150 can be welded to the aforementioned first tab 131. This establishes an electrical connection between the first tab 131 (negative tab) of the electrode assembly 130 and the current collector 150, the cover plate 140, and the housing 110, such that the housing 110 and the first tab 131 have the same polarity (e.g., negatively charged) and serve as the output electrode. In the event of thermal runaway, since the center portion 154 of the current collector 150 is welded to the cover plate 140, the current collector 150 can be pulled out of the housing when the explosion-proof valve opens. Furthermore, due to the multiple first through slots 201 causing the current collector 150 to form an umbrella-like convergence, the current collector 150 can be detached from the explosion-proof valve opening along with the cover plate 140.

[0046] The central portion 154 also has a buffer portion 158 surrounding the boss 156. The buffer portion 158 may be a rib surrounding the boss 156. During battery use, gas generation inside the casing may cause the cover plate 140 to bulge and deform, pulling on the boss 156. If the dividing portion 152 is pulled along with the boss 156, the weld between the dividing portion 152 and the electrode tab may break. By providing the buffer portion 158, the force of pulling on the boss 156 can be prevented from being transmitted to the dividing portion 152, thereby preventing the weld between the dividing portion 152 and the electrode tab from breaking.

[0047] The dividing portion 152 has an outer edge 152e away from the center of the current collecting member 150. The outer edge 152e is arc-shaped. In some embodiments, at the outer edge 152e of the dividing portion 152, the dividing portion 152 has two adjacent corners 152c corresponding to the first through groove 201. In some embodiments, each corner 152c is a rounded corner. The dividing portion 152 adopts an arc-shaped outer edge 152e and a rounded corner design to prevent sharp corners from affecting the structural strength.

[0048] In some embodiments, the end 201e of the first through groove 201 is arc-shaped. The first through groove 201 includes two opposing sidewalls 201s, which extend radially along the collecting member 150. The two sidewalls 201s are respectively connected to the arc-shaped end 201e and the corresponding angle 152c. The first through groove 201 may be defined by the end 201e, the two sidewalls 201s, and the two corresponding angles 152c. In a direction perpendicular to the radial direction of the collecting member 150, the interval between the two sidewalls 201s is defined as the width w of the first through groove 201. In some embodiments, the width w of the first through groove 201 is 0.5mm-2mm. In some embodiments, the diameter of the angle 152c is the same as the width w of the first through groove 201. In some embodiments, the length of the first through groove 201 extending radially into the collecting member 150 is 2mm-10mm.

[0049] Figure 5 This is an isometric view of the current collection member 150 according to another embodiment of this application. Figure 5 In the illustrated embodiment, each segment 152 of the manifold 150 facing the cover plate 140 has a notch 230. The notch 230 extends longitudinally from the outer edge 152e of the segment 152 toward the central hole 150v. In some embodiments, the notch 230 may extend radially along the manifold 150. In some embodiments, the longitudinal extension length of the notch 230 may be the same as the length of the first through groove 201. In some embodiments, the maximum width of the notch 230 is 0.5mm-2mm. In some embodiments, the depth of the notch 230 is 70%-30% of the thickness of the manifold, and correspondingly, the residual thickness of the manifold 150 below the notch 230 is 30%-70% of the thickness of the manifold. By adding notches 230 to the segment 152, it is more conducive to the manifold 150 forming an umbrella-like shape in the event of thermal runaway, so that the manifold 150 can be dislodged from the explosion-proof valve opening, thereby reducing the risk of the manifold clogging the explosion-proof valve opening.

[0050] Figure 6 This is an isometric view of the current collection member 150 according to another embodiment of this application. Figure 6 In the illustrated embodiment, the current collecting member 150 further includes a plurality of second through slots 202 extending through the current collecting member 150 in its thickness direction, wherein each second through slot 202 is connected to the end 201e of the corresponding first through slot 201 (see...). Figure 4A and Figure 4BThe longitudinal extension direction of each second through groove 202 may be perpendicular to the longitudinal extension direction of the corresponding first through groove 201. In some embodiments, the opposite ends of the second through groove 202 in the longitudinal direction may be arc-shaped. The segment 152 is separated by the first through groove 201 and the second through groove 202. By further providing the second through groove 202, the size of the segment 152 connected to the root of the central portion 154 can be reduced, so that in the event of thermal runaway, the segment 152 of the manifold 150 can be more easily folded over, so that the manifold 150 can be dislodged from the explosion-proof valve opening.

[0051] In some embodiments, the widths of the first through groove 201 and the second through groove 202 are 0.5 mm to 2 mm, respectively. The first through groove 201 and the second through groove 202 can form a T-shaped slot. Along the radial direction of the flow collecting member 150, the T-shaped slot extends into the flow collecting member 150 for a length of 2 mm to 10 mm. In some embodiments, the width b (the straight-line distance between the ends of the second through groove 202) of each segment 152 connected to the end of the central portion 154 can be 2 mm to 5 mm.

[0052] Figure 7 This is an isometric view of the current collection member 150 according to another embodiment of this application. Figure 7 In the illustrated embodiment, a welding area 190 is shown formed by welding the dividing portion 152 to the electrode tab. For clarity, Figure 7 Only the welding area 190 on one segment 152 is shown. It should be understood that the welding areas on other segments 152 can be arranged similarly.

[0053] The first end 19a of the welding region 190 is adjacent to the buffer portion 158, and the width of the welding region 190 increases in the direction radially away from the buffer portion 158 from the first end 190a. That is, the portion of the welding region 190 adjacent to the buffer portion 158 has a smaller width, and the portion away from the buffer portion 158 has a larger width. In this embodiment, the end of the welding region 190 away from the buffer portion 158 has an arc shape, making the welding region 190 have a teardrop-like shape. In other embodiments, the welding region 190 may also have other shapes with the above-described width configuration, such as a fan shape. In some embodiments, a plurality of welding regions 190 on a segment 152 are evenly (equally spaced). Since the portion of the welding region 190 adjacent to the buffer portion 158 has a smaller width, it is advantageous for this portion of the welding region to break quickly in the event of thermal runaway, ensuring that the current collector can be smoothly removed and effectively discharged. Furthermore, since the portion of the welding region 190 away from the buffer portion 158 has a larger width, it provides a sufficient welding area for welding to the tab.

[0054] Figure 8This is an isometric view of the current collection member 150 according to another embodiment of this application. Figure 8 In the illustrated embodiment, each segment 152 has multiple weld lines 170 formed by welding it to the electrode tab. Figure 8 In this embodiment, each segment 152 has three bonding lines 170, but in other embodiments, the bonding lines 170 may have other numbers. Each bonding line 170 has a sinusoidal shape. Specifically, each bonding line 170 is a sinusoidal shape that oscillates back and forth along a corresponding reference line Lr.

[0055] On each segment 152, the included angle α between the reference lines Lr corresponding to every two adjacent weld lines 170 can be equal, thus allowing the multiple weld lines 170 on each segment 152 to be evenly distributed. In some embodiments, the included angle α between the reference lines Lr corresponding to every two adjacent weld lines 170 is 15°-90°. In the direction away from the center of the current collector 150, the interval between the reference lines Lr corresponding to every two adjacent weld lines 170 on each segment 152 gradually increases. Thus, the three weld lines 170 on each segment 152 can be considered to be distributed in a fan shape. This fan-shaped distribution of the weld lines 170 facilitates the rapid breakage of the weld lines on the segment 152 in the event of thermal runaway, ensuring that the current collector can be smoothly detached and effectively discharged.

[0056] Along the direction of the reference line Lr, the distance between the two ends of the weld wire 170 is defined as the length d of the weld wire 170. In some embodiments, the length d of a single weld wire 170 can be 5mm-10mm. Along the direction perpendicular to the reference line Lr, the difference between the crests and troughs of the sinusoidal weld wire 170 is defined as the width m of the weld wire 170. In some embodiments, the width m of the weld wire 170 is 0.5mm-2mm. Since the sinusoidal weld wire 170 provides strong welding strength, this may make the weld wire difficult to break during thermal runaway, and the current collector difficult to detach smoothly. By setting the width m of the weld wire 170 to 0.5mm-2mm, the area of ​​a single weld wire 170 region can be appropriately reduced, thereby making it easier to break during thermal runaway, so as to facilitate the smooth detachment of the current collector.

[0057] Furthermore, each bonding wire 170 may include a head portion 170a adjacent to the center of the current collector 150 and a tail portion 170b distant from the center of the current collector 150. In some embodiments, the head portion 170a may be a portion of the bonding wire connected to one end of the bonding wire 170 adjacent to the central hole 150v. The tail portion 170b may be a portion of the bonding wire 170 connected to one end of the bonding wire 170 distant from the central hole 150v. In some embodiments, the head portion 170a is 10%-50% of the length d of the bonding wire 170, and the tail portion 170b is 50%-90% of the length d of the bonding wire 170. The head portion 170a can be used for bonding to the tabs of the inner ring of the electrode assembly, and the tail portion 170b can be used for bonding to the tabs of the outer ring of the electrode assembly.

[0058] For a single welding line 170, the first part 170a is welded to the first layer of tabs, and the last part 170b is welded to the second layer of tabs, with the first layer being less than the second layer. That is, the inner ring's first part 170a has a weaker weld strength and is welded to fewer layers of tabs; the outer ring's last part 170b has a stronger weld strength and is welded to more layers of tabs. In such an embodiment, low-power welding (e.g., 800W-1200W) can be used to form the first part 170a of the welding line 170 to maintain a certain weld strength and current-carrying capacity; and conventional power welding (e.g., 1200W-1600W) can be used to form the last part 192. This design, with different weld strengths for the first and last parts, provides a stress concentration zone, which is beneficial for the first part 170a of the inner ring to disconnect preferentially in the event of thermal runaway. This facilitates the detachment of the current collector 150 and the electrode assembly after the explosion-proof valve opens, thereby ensuring effective venting.

[0059] See Figure 9 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 9 A schematic diagram is shown when the electronic device according to an embodiment of this application is a vehicle.

[0060] 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.

[0061] 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 being welded to the tab, wherein the current collecting member includes a plurality of first through-slots penetrating the current collecting member in a thickness direction of the current collecting member, the plurality of first through-slots being arranged around a center of the current collecting member, each of the first through-slots extending along a radial direction of the current collecting member from an edge of the current collecting member, and an end of each of the first through-slots adjacent to the center being located in a projection area of the explosion-proof valve in an axial direction of the current collecting member.

2. The secondary battery according to claim 1, wherein: the current collecting member includes a plurality of divided portions separated by the plurality of first through-slots, wherein, at a circular-arc outer edge of each of the divided portions away from the center, an angle of the divided portion adjacent to the corresponding first through-slot is rounded.

3. The secondary battery according to claim 1, wherein: the current collecting member further includes a plurality of second through-slots penetrating the current collecting member in the thickness direction of the current collecting member, wherein each of the second through-slots communicates with the end of the corresponding first through-slot, and a longitudinal extension direction of each of the second through-slots is perpendicular to a longitudinal extension direction of the corresponding first through-slot.

4. The secondary battery according to claim 1, wherein: the current collecting member includes a plurality of divided portions separated by the plurality of first through-slots, and each of the divided portions is provided with a score on a surface thereof facing the cover plate, the score extending longitudinally from an outer edge of the divided portion away from the center toward the center.

5. The secondary battery according to claim 1, wherein: the current collecting member includes a plurality of divided portions separated by the plurality of first through-slots, and a center portion connected to the plurality of divided portions, the center portion has a boss arranged around the center and a buffer portion arranged around the boss.

6. The secondary battery according to claim 5, wherein: each of the divided portions has a welding area formed by welding to the tab, wherein a first end of the welding area is adjacent to the buffer portion, and a width of the welding area increases in a direction away from the buffer portion along the radial direction from the first end of the welding area.

7. The secondary battery according to claim 5, wherein: each of the divided portions has a plurality of welding lines formed by welding to the tab, each of the welding lines having a sinusoidal waveform shape reciprocatingly fluctuating along a corresponding reference line, wherein, in a direction away from the center, a spacing between the reference lines corresponding to each of the two adjacent welding lines on each of the divided portions gradually increases, in a direction perpendicular to the reference line, a difference between a peak and a trough of the welding line having the sinusoidal waveform shape is 0.5 mm-2 mm.

8. The secondary battery according to claim 5, wherein: Each of the divided portions has a plurality of welding lines formed by welding with the tab, each of the welding lines including a head portion adjacent to the center and a tail portion away from the center, the head portion being welded with the tab of a first layer number, the tail portion being welded with the tab of a second layer number, the first layer number being smaller than the second layer number.

9. The secondary battery according to any one of claims 1 to 8, characterized in that The center portion of the current collecting member is welded and connected with the cover plate, and the cover plate is connected with the case, so that the case and the tab have the same polarity.

10. A battery pack characterized by comprising: A secondary battery as claimed in any one of claims 1 to 9.

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