Secondary battery, battery pack, and electronic device

Abstract

To provide a secondary battery, a battery pack, and an electronic device capable of improving a technical problem that welding failure of a current collecting member and a tab easily occurs in a mechanical sealing process of a cylindrical battery.SOLUTION: The secondary battery includes a case, an electrode member, and a current collecting member. The case includes a side wall, an opening is provided at one end of the side wall, and one end of the side wall close to the opening includes a rolling groove. The electrode member is accommodated in the case, and the electrode member includes a tab facing the opening. The current collecting member includes a current collecting body and a plurality of case connecting portions annularly connected to an outer periphery of the current collecting body, the current collecting body includes a plurality of tab connecting portions fixedly connected to the tabs, the case connecting portion includes a bending portion and a straight portion connected to the current collecting body, and the bending portion is welded to a surface of the rolling groove facing the electrode member. Along a circumferential direction of the housing, the housing connection portion is located between two adjacent tab connection portions, a through hole is provided between the two adjacent tab connection portions, and a first connection portion is formed between each tab connection portion and the straight portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the field of battery technology, and more particularly to secondary batteries, battery packs, and electronic devices. [Background technology]

[0002] Mechanical sealing is the mainstream packaging method for conventional cylindrical batteries and is widely used due to the advantages of mature processes and equipment and fast production cycle times. In conventional cylindrical batteries, a current collecting member is typically placed near the opening of the case, one end of the current collecting member is welded to the side wall of the case, and the other end is electrically connected to the tab of the electrode member, thereby achieving electrical connection between the case and the electrode member. Mechanical sealing is then performed. This involves rolling a recessed groove into the side wall of the case toward the inside of the case, and then crimping a cover plate using a stamping method. During this process, bending stress generated by the current collecting member can cause the current collecting member to warp internally, tearing the weld between the current collecting member and the tab, which can result in the risk of losing electrical connection to the electrode member. Summary of the Invention [Problem to be solved by the invention]

[0003] In view of the above-mentioned drawbacks of the prior art, the present invention provides a secondary battery, a battery pack, and an electronic device that solve the technical problem of welding failure between the current collecting member and the tab during the mechanical sealing process of a cylindrical battery. [Means for solving the problem]

[0004] In order to achieve the above and other related objects, the present invention provides a secondary battery comprising: a case including an annular side wall, one end of the side wall having an opening, and one end of the side wall nearest the opening having a rolling groove recessed toward the inside of the case; an electrode member housed within the case and including a tab facing the opening; and a current collecting member including a current collector body and a plurality of case connection portions annularly connected to the outer periphery of the current collector body, wherein the current collector body includes the plurality of tab connection portions fixedly connected to the tabs, and the case connection portion includes a bent portion bent toward the axis of the case and a straight portion connected to the current collector body, and the bent portion includes a current collecting member welded to a surface of the rolling groove facing the electrode member, and the case connection portions are located between adjacent two tab connection portions along the circumferential direction of the case, a through hole is provided between each adjacent two tab connection portions, and a first connection portion is formed between each tab connection portion and the straight portion.

[0005] In the above technical solution, the case connection portion is located between two adjacent tab connection portions along the circumferential direction of the case, and the case connection portions and the tab connection portions are alternately arranged along the circumferential direction of the case, so that when the case connection portion is bent, the bending stress transmitted to the current collector body does not directly act on the tab connection portion, and the transmission of the bending stress to the tab connection portion is weakened.

[0006] Additionally, a through hole is provided between each adjacent tab connection portion, and a first connection portion is formed between each tab connection portion and the straight portion. The through hole reduces the width of the first connection portion, reducing the bending stress transmitted to the tab connection portion. At the same time, the reduced strength of the first connection portion makes it more susceptible to deformation under bending stress, absorbing partial bending stress and further reducing the bending stress transmitted to the tab connection portion, thereby improving the problem of weld failure between the current collecting member and the tab due to bending stress.

[0007] In one embodiment of the secondary battery of the present invention, a notch is provided between the straight portion and the tab connection portion, and the first connection portion is located between the notch and the through hole.

[0008] In the above technical solution, the installation of the notch can further reduce the strength of the first connection part, making it more deformable and absorbing more stress, and ultimately further reducing the transmission of bending stress to the tab connection part.

[0009] In one embodiment of the secondary battery of the present invention, if the sum of the minimum current passing areas of all the first connection portions is a and the total area of ​​the weld lines formed by welding the tab connection portions and the tabs is s, then a>s.

[0010] In the above technical solution, the minimum current-passing area of ​​the first connection part is the smallest point of the cross-sectional area of ​​each first connection part along the circumferential direction of the current collecting member, and the total area of ​​the weld line refers to the area of ​​all the weld lines formed by welding the tab connection parts to the tabs, projected along the axial direction of the electrode member. By setting the sum a of the minimum current-passing areas of all the first connection parts to be greater than the total area of ​​the weld line, it is possible to weaken the transmission of bending stress while not affecting the current-carrying effect of the first connection part.

[0011] In one embodiment of the secondary battery of the present invention, the straight portion includes a first weak portion.

[0012] In the above technical solution, by installing the first weak part in the straight part, it is possible to reduce the stress generated when the case connection part is bent. At the same time, because the strength of the first weak part is low, the first weak part in the straight part will take the lead in deforming under the action of stress, reducing the transmission of stress to the welded connection part between the current collecting member and the tab, and ultimately alleviating the problem of weld failure between the current collecting member and the tab due to bending stress.

[0013] In one embodiment of the secondary battery of the present invention, the first weak portion includes one or a combination of a thin portion, a notch, and a hollowed-out portion.

[0014] In the above-mentioned technical solution, one or a combination of the thin-walled portion, the notch, and the hollowed-out portion can all achieve the effect of reducing the strength of the first weak portion by reducing the cross-sectional area of ​​the first weak portion.

[0015] In one embodiment of the secondary battery of the present invention, when the sum of the minimum current passing areas of all the first weak parts is b and the total area of ​​the weld line formed by welding the current collector body and the tab is s, b>s.

[0016] In the above technical solution, the minimum current-passing area of ​​the first weak parts is the smallest point of the cross-sectional area of ​​each first weak part along the circumferential direction of the current collecting member, and the total area of ​​the weld lines refers to the area of ​​all the weld lines formed by welding the tab connection parts to the tabs, projected along the axial direction of the electrode member. By setting the sum b of the minimum current-passing areas of all the first weak parts to be greater than the total area of ​​the weld lines, it is possible to weaken the transmission of bending stress while not affecting the current-carrying effect of the first weak parts.

[0017] In one embodiment of the secondary battery of the present invention, the thin-walled portion and the notch both form grooves in the straight portion, and the grooves are located on the side of the current collector body facing the electrode member.

[0018] In the above technical solution, the bending stress generated at the case connection portion causes the tab connection portion to warp upward, and similarly, the first weak portion of the straight portion also tends to bulge in a direction away from the electrode member. If the groove is located on the side of the current collector body away from the electrode member, there is a risk of the first weak portion breaking when it bulges. Therefore, by locating the groove on the side of the current collector body facing the electrode member, it is possible to weaken the bending stress transmission and reduce the risk of breaking at the first weak portion.

[0019] In one embodiment of the secondary battery of the present invention, a central hole is provided in the center of the collector body, and a second weak portion is included between each through hole and the central hole, and the second weak portion is configured to rupture when the internal pressure of the secondary battery exceeds a threshold value, thereby connecting the central hole and the through hole in the radial direction of the secondary battery.

[0020] In the above-mentioned technical solution, when the internal pressure exceeds a threshold, the second weak part breaks, the central hole and the through hole are connected, and the current collector body is divided into multiple thin pieces. Under the impact of the internal pressure, each thin piece in the middle of the current collector body is folded back in the direction away from the electrode member, further reducing the obstruction area and contributing to the release of internal substances of the secondary battery, thereby contributing to preventing the secondary battery from exploding, and improving the safety performance of the secondary battery.

[0021] The present invention also provides a battery pack including any of the above secondary batteries.

[0022] The present invention also provides an electronic device including the above-described battery pack. [Effects of the Invention]

[0023] In the secondary battery of the present invention, the case connection portion is located between two adjacent tab connection portions along the circumferential direction of the case, and the case connection portions and the tab connection portions are arranged alternately in the circumferential direction of the case. With this arrangement, when the case connection portion bends, the bending stress transmitted to the current collector body does not act directly on the tab connection portion, and the bending stress transmitted to the tab connection portion can be reduced.

[0024] In addition, a through hole is provided between two adjacent tab connection portions, and a first connection portion is formed between each tab connection portion and the straight portion. The presence of the through hole reduces the width of the first connection portion, thereby reducing the bending stress transmitted to the tab connection portion. At the same time, the weakened strength of the first connection portion makes it easier for the first connection portion to deform under the action of bending stress, absorbing partial bending stress and further reducing the transmission of bending stress to the tab connection portion, thereby alleviating the problem of weld failure between the current collecting member and the tab due to bending stress. [Brief explanation of the drawings]

[0025] In order to more clearly describe the embodiments of the present invention or the technical solutions of the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below. Of course, the drawings in the following description are only some embodiments of the present invention. Those skilled in the art can obtain other embodiments based on these drawings without expending creative efforts. [Figure 1] 1 is an explanatory diagram of the overall structure of an embodiment of a secondary battery of the present invention; [Figure 2] 1 is a structural explanatory diagram of an electrode member of an embodiment of a secondary battery of the present invention. [Figure 3] 3 is a structural explanatory view of a current collecting member of an embodiment of a secondary battery of the present invention before being folded. FIG. [Figure 4] FIG. 4 is a top view of the current collecting member shown in FIG. [Figure 5] FIG. 6 is a structural explanatory view of a current collecting member of a secondary battery according to a second embodiment of the present invention before being folded. [Figure 6] FIG. 6 is a partial enlarged view of a portion A in FIG. 5. [Figure 7] FIG. 6 is a top view of the current collecting member shown in FIG. [Figure 8] FIG. 6 is a bottom view of the current collecting member shown in FIG. [Figure 9] FIG. 10 is a structural explanatory view of a current collecting member of a secondary battery according to a third embodiment of the present invention before being folded. [Figure 10] FIG. 10 is a top view of the current collecting member shown in FIG. [Figure 11] 1 is an explanatory diagram of an embodiment of a battery pack of the present invention. [Figure 12] 1 is an explanatory diagram of an embodiment of an electronic device of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0026] The following describes the implementation of the present invention through certain specific embodiments, so that those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed herein. The present invention can be implemented or applied in other different specific embodiments, and the details of each item in this specification can be modified or changed in various ways based on different perspectives and applications without departing from the spirit of the present invention. Where not inconsistent, the following embodiments and features therein can be combined with each other. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific implementations and are not intended to limit the scope of protection of the present invention. In the following embodiments, test methods for which specific conditions are not specified are usually performed according to general conditions or conditions recommended by each manufacturer.

[0027] When a numerical range is indicated in this embodiment, it should be understood that any numerical value between the endpoints of each numerical range can be selected unless otherwise specified in the present invention. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those skilled in the art understand in the existing technology and described in the present invention, and the present invention can be realized using any method, equipment, and material in the existing technology that is similar or equivalent to the method, equipment, and material described in the embodiments of the present invention.

[0028] Furthermore, terms such as "upper," "lower," "left," "right," "middle," and "one" cited in this specification are merely for the purpose of clarifying the description and do not limit the scope in which the present invention can be implemented. Changes or adjustments to their relative relationships are considered to be within the scope in which the present invention can be implemented, provided that there is no substantial change in the technical content.

[0029] A secondary battery includes an electrode member, which is a member that causes an electrochemical reaction in the secondary battery, and can include one or more electrode members.

[0030] The secondary battery further includes a case, a cover plate, and electrode posts, the case including end walls and side walls surrounding the end walls, one end of the side walls having an opening, the electrode members being able to be assembled into the case through the opening of the case, the cover plate being used to cover the opening of the case and achieve sealing, and the electrode posts penetrating the end walls and electrically connecting with the electrode members to conduct the power generated by the electrode members.

[0031] The mainstream sealing method for conventional secondary batteries is mechanical sealing, which has the advantages of mature processes and equipment and fast production cycle times and is widely used. The current collecting member is simultaneously electrically connected to the electrode member and the case, thereby achieving an electrical connection between the electrode member and the case. Specifically, a circumferential rolling groove is first rolled into the side wall of the case, recessed toward the inside of the case, and the side of the rolling groove closest to the electrode member is pressed against the edge of the current collecting member, which can limit the axial displacement of the electrode member. A cover plate is installed on a step formed on the side of the rolling groove away from the electrode member, and a sealing member is installed between the cover plate and the case. Furthermore, a hammer-in sealing method is used to press the sealing member against the cover plate at the edge of the opening, forming a reliable connection and achieving a sealed case.

[0032] There are various methods for connecting the current collecting member and the case. One commonly used method is to install a case connection part on the edge of the current collecting member, first weld the case connection part to the side wall of the case, and then roll a rolling groove on the side wall so that the case connection part is continuously bent toward the axis of the case. However, the inventor discovered that when the case connection part is bent toward the axis of the case, bending stress is generated, and the bending stress is further transmitted to the inside of the current collecting member, causing the current collecting member to warp up, and the welded part between the current collecting member and the tab is torn, which creates a risk of the electrical connection of the electrode member being lost.

[0033] In view of this, the present invention provides a technical solution in which the case connection parts and the tab connection parts are arranged alternately around the circumferential direction of the case. This arrangement ensures that when the case connection parts are bent, the bending stress transmitted toward the current collector body does not directly act on the tab connection parts, thereby reducing the bending stress transmitted toward the tab connection parts and further alleviating the problem of weld failure between the current collecting member and the tab due to bending stress.

[0034] 1 to 12, the present invention provides a secondary battery 100, which includes a case 110, an electrode member 120, a pole 140, and a current collecting member 150.

[0035] 1 , case 110 includes end wall 111 and side wall 112 surrounding end wall 111. The connection between end wall 111 and side wall 112 can be realized in various ways, such as integral press molding, integral casting, or split welding, as long as a stable sealing and electrical connection can be formed. The shape of side wall 112 is not limited and can be cylindrical or prismatic, or can be any other closed loop shape compatible with end wall 111. In this embodiment, end wall 111 has a circular outer periphery, and side wall 112 cylindrically surrounds the outer periphery of end wall 111, forming a circular opening 113 at one end of side wall 112 away from end wall 111. A chamber is formed within case 110, surrounded by end wall 111 and side wall 112, and used to accommodate electrode components 120, electrolyte, and other components required for the battery. Specifically, the diameter of the case 110 can be determined based on the specific dimensions of the electrode member 120, and may be 18 mm, 21 mm, 46 mm, etc. The case 110 may be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc., and the surface of the case 110 may be further plated with a layer of anti-corrosion material such as metallic nickel to prevent the case 110 from rusting during long-term use.

[0036] 1 and 2, an electrode member 120 is installed inside the case 110, and the electrode member 120 is a member where an electrochemical reaction occurs in the secondary battery 100. The case 110 may contain one or more electrode members 120. The electrode member 120 includes an electrode sheet and a separator 122, and the electrode sheet and the separator 122 are wound together to form a wound structure. Specifically, in this embodiment, the electrode member 120 includes a positive electrode sheet 121, a separator 122, and a negative electrode sheet 123 wound around the axial direction of the case 110.

[0037] 1 and 2, the positive electrode sheet 121 includes a positive electrode current collector 1211 and a positive electrode active material layer coated on the positive electrode current collector 1211. A first coated region 1212 coated with the positive electrode active material layer and a first uncoated region 1213 not coated with the positive electrode active material layer are formed on the positive electrode current collector 1211. The first coated region 1212 and the first uncoated region 1213 are arranged along the axial direction of the case 110. The first uncoated region 1213 extends out of the separator 122 toward one end in the height direction of the secondary battery 100 and bends toward the axis of the case 110 to form a stacked positive electrode tab 125.

[0038] 1 and 2, the negative electrode sheet 123 includes a negative electrode current collector 1231 and a negative electrode active material layer coated on the negative electrode current collector 1231. A second coated region 1232 coated with the negative electrode active material layer and a second uncoated region 1233 not coated with the negative electrode active material layer are formed on the negative electrode current collector 1231. The second coated region 1232 and the second uncoated region 1233 are arranged along the axial direction of the case 110. The second uncoated region 1233 extends outside the separator 122 toward the other end of the height direction of the secondary battery 100 and bends toward the axis of the case 110 to form a stacked negative electrode tab 124.

[0039] 1 and 2, separator 122 is disposed between positive electrode sheet 121 and negative electrode sheet 123 to separate the positive electrode active material layer from the negative electrode active material layer. Taking battery 100 as an example of a lithium-ion secondary battery, the material of positive electrode current collector 1211 may be aluminum, the positive electrode active material layer includes a positive electrode active material, which may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The material of negative electrode current collector 1231 may be copper, and the negative electrode active material layer includes a negative electrode active material, which may be carbon or silicon, etc. The substrate material of separator 122 may be polypropylene (PP) or polyethylene (PE), etc. To protect and insulate the battery cell, the outside of the battery cell can be coated with an insulating film, which can be made of PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC) or other high molecular weight polymer materials.

[0040] 1 and 2, when the positive electrode tab 125 in the present invention faces the end wall 111 or faces the opening 113, the negative electrode tab 124 faces the other end of the case 110, and in this embodiment, the positive electrode tab 125 faces the end wall 111 and is electrically connected to the electrode post 140, making the electrode post 140 positively charged, and the negative electrode tab 124 faces the opening 113 and is electrically connected to the case 110, making the negative electrode tab 124 negatively charged. However, in other embodiments, the negative electrode tab 124 may be connected to the electrode post 140, and the positive electrode tab 125 may be connected to the case 110.

[0041] 1 , the cover plate 130 is fitted to the opening 113 with a sealing seal. The outer edge of the cover plate 130 corresponds to the shape of the opening 113 and connects with the side wall 112 to seal the opening 113. In a specific embodiment, a rolling groove 114 is formed by rolling a circumference of the side wall 112 of the case 110 in an area near the outer edge thereof. The rolling groove 114 is recessed toward the inside of the case 110. The rolling groove 114 includes a first side wall 1141 and a second side wall 1142. The first side wall 1141 is close to the electrode member 120 and can limit the axial displacement of the electrode member 120. The second side wall 1142 is annularly surrounding the case 110 on the side away from the rolling groove 114, forming an annular step. The cover plate 130 is placed on the step. A seal ring is installed between the cover plate 130 and the annular groove 1121. The edge of the opening 113 is sealed by a press-fitting method, with the cover plate 130 pressing the seal ring to form a reliable connection.

[0042] 1 and 2, the electrode post 140 is fixed to the end wall 111 and electrically connected to the electrode member 120. Specifically, an electrode post hole is provided in the end wall 111, and the electrode post 140 is attached by penetrating into the electrode post hole and is insulated from the end wall 111. One end of the electrode post 140 facing the electrode member 120 penetrates the end wall 111 and is electrically connected to the positive electrode tab 125 directly or indirectly by connecting the end wall 111 and electrically connected to the positive electrode tab 125 of the electrode member 120. The structural form of the electrode post 140 may be any suitable form that can penetrate the end wall 111 and electrically connect to the positive electrode tab 125 of the electrode member 120. For example, the cross section may be circular, rectangular, prismatic, or a modified profile that can achieve stable conductivity. The shape of the electrode post hole and the shape of the electrode post 140 correspond to each other. In this embodiment, the cross section of the electrode post 140 is circular.

[0043] 1 , the current collecting member 150 is disposed between the electrode member 120 and the cover plate 130, and the case 110 and the electrode member 120 are electrically connected through the current collecting member 150. Specifically, the current collecting member 150 includes a current collecting body 151 and a case connecting part 152 connected to the outer periphery of the current collecting body 151. The case connecting part 152 may be an integral ring structure or one or more fan-shaped ring structures, as long as it satisfies the current conduction requirements and welding strength requirements between the current collecting member 150 and the case 110. The case connection portion 152 includes a bent portion 1521 that bends toward the axis of the case 110 and a straight portion 1522 that connects to the collector body 151. Before the rolling groove 114 is rolled into the case 110, the bent portion 1521 is first welded to the side wall 112 of the case 110. At the same time as the rolling groove 114 is rolled, the bent portion 1521 welded to the case 110 continues to bend toward the axis of the case 110, and finally forms a shape that is bent toward the axis of the case 110, and is welded to the surface of the rolling groove 114 that faces the electrode member 120.

[0044] 3 to 5, 7, and 10, the current collector body 151 is fixedly connected to the tabs. The connection between the current collector body 151 and the tabs can be achieved in a variety of ways, such as by welding or by using a conductive adhesive, as long as it achieves electrical connection between the current collecting member 150 and the tabs and satisfies current conduction requirements. In this embodiment, a welding connection is used. Furthermore, the current collector body 151 includes a plurality of tab connections 153 that are welded to the tabs. The number, shape, and position of the tab connections 153 are not limited. Preferably, in this embodiment, the current collector body 151 includes four tab connections 153 that are welded to the tabs. The four tab connections 153 are evenly spaced around the circumference of the current collector body 151. This arrangement improves the welding balance between the current collecting member 150 and the tabs and provides a more uniform current conduction effect, thereby improving the stability of current conduction between the case 110 and the electrode member 120.

[0045] When case connection portion 152 bends toward the axis of case 110, bending stress is generated, and this bending stress is transmitted to the inside of current collecting member 150, causing further technical problems such as internal warping of current collecting member 150. In consideration of this, referring to Figures 3 to 5, 7 and 10, case connection portion 152 is positioned between two adjacent tab connection portions 153 along the circumferential direction of case 110, and case connection portion 152 and tab connection portion 153 are arranged alternately in the circumferential direction of case 110. With this arrangement, when case connection portion 152 bends, the bending stress transmitted to current collecting body 151 does not directly act on tab connection portion 153, and the transmission of the bending stress to tab connection portion 153 can be weakened.

[0046] 3 to 5, 7, and 10, a through hole 154 is provided between two adjacent tab connection portions 153. The shape of the through hole 154 is not limited and may be circular, rectangular, sector-shaped, diamond-shaped, or other irregular shapes. A first connection portion 155 is formed between each tab connection portion 153 and the straight portion 1522. The shape of the first connection portion 155 depends on the shape of the through hole 154. The presence of the through hole 154 reduces the width of the first connection portion 155, thereby reducing the bending stress transmitted to the tab connection portion 153. At the same time, the strength of the first connection portion 155 is weakened, making the first connection portion 155 more susceptible to deformation under the action of bending stress. This allows the first connection portion 155 to absorb partial bending stress and further reduce the transmission of bending stress to the tab connection portion 153, thereby improving the problem of weld failure between the current collecting member 150 and the tab due to bending stress.

[0047] 3 to 5, 7, and 10, in one embodiment of the secondary battery 100 of the present invention, a notch 156 is provided between the straight portion 1522 and the tab connection portion 153. The first connection portion 155 is located between the notch 156 and the through hole 154, and the shape of the notch 156 may be various, for example, rectangular, fan-shaped, or other irregular shapes, but is not limited thereto. The provision of the notch 156 can further reduce the strength of the first connection portion 155, making it more easily deformable and absorbing more stress, ultimately further reducing the transmission of bending stress to the tab connection portion 153.

[0048] 3 to 5, 7, and 10, in one embodiment of the secondary battery 100 of the present invention, the sum of the minimum current passing areas of all first connection portions 155 is a, the total area of ​​the weld lines formed by welding the tab connection portions 153 to the tabs is s, and a > s. The minimum current passing area of ​​the first connection portions 155 is the smallest point in the cross-sectional area of ​​each first connection portion 155 along the circumferential direction of the current collecting member 150, and the total area of ​​the weld lines refers to the area of ​​all the weld lines formed by welding the tab connection portions 153 to the tabs, projected along the axial direction of the electrode member 120. By setting the sum of the minimum current passing areas of all first connection portions 155, a, to be larger than the total weld line area, it is possible to weaken bending stress transmission while preventing the current flow effect of the first connection portions 155 from being affected.

[0049] 5 to 8, in one embodiment of the secondary battery 100 of the present invention, the straight portion 1522 includes a first weak portion 1523. This arrangement can reduce the stress generated when the case connection portion 152 is bent. At the same time, because the strength of the first weak portion 1523 is low, the first weak portion 1523 of the straight portion 1522 will deform first under stress, reducing the transmission of stress to the welded connection portion between the current collecting member 150 and the tab, and further alleviating the problem of weld failure between the current collecting member 150 and the tab due to bending stress.

[0050] 5 to 8 , in one embodiment of the secondary battery 100 of the present invention, the first weak portion 1523 includes one or a combination of a thinned portion, a notch, and a cutout. In some embodiments, only a thinned portion, a notch, or a cutout is provided, while in other embodiments, a combination of a thinned portion and a cutout, or a combination of a notch and a cutout, may be provided. It is sufficient to reduce the cross-sectional area of ​​the first weak portion 1523, weaken the strength of the first weak portion 1523, and facilitate bending of the straight portion 1522 at the first weak portion 1523. In any of the above forms, the effect of reducing the strength of the first weak portion 1523 can be achieved by reducing the cross-sectional area of ​​the first weak portion 1523.

[0051] 5 to 8 , in one embodiment of the secondary battery 100 of the present invention, the minimum current passage area of ​​all first weak portions 1523 is b, the total area of ​​the weld lines formed by welding the current collector body 151 and the tabs is s, and b > s. Note that the minimum current passage area of ​​the first weak portions 1523 is the smallest point in the cross-sectional area of ​​each first weak portion 1523 along the circumferential direction of the current collecting member 150, and the total area of ​​the weld lines refers to the area of ​​all the weld lines formed by welding the tab connection portions 153 and the tabs, projected along the axial direction of the electrode member 120. By setting the sum b of the minimum current passage areas of all first weak portions 1523 to be larger than the total weld line area s, it is possible to weaken bending stress transmission while preventing the current-carrying effect of the first weak portions 1523 from being affected.

[0052] 5 to 8 , in one embodiment of the secondary battery 100 of the present invention, both the thinned portion and the notches form grooves 1524 in the straight portion 1522. Considering that bending stress generated in the case connection portion 152 causes the tab connection portion 153 to warp upward, the first weak portion 1523 of the straight portion 1522 also tends to bulge in a direction away from the electrode member 120. If the grooves 1524 are located on one side of the current collector body 151 facing away from the electrode member 120, there is a risk of the first weak portion 1523 breaking when the first weak portion 1523 bulges. Preferably, in this embodiment, the grooves 1524 are located on one side of the current collector body 151 facing the electrode member 120. This arrangement reduces the transmission of bending stress and also reduces the risk of breaking the first weak portion 1523.

[0053] 3 and 4, in one embodiment of the secondary battery 100 of the present invention, a central hole 157 is provided in the center of the current collector body 151. The shape of the central hole 157 is not limited and may be a circular hole, a square hole, a diamond-shaped hole, a polygonal hole, or any other hole with an irregular closed outline. Second weak parts 158 are included between each through hole 154 and the central hole 157. The second weak parts 158 rupture when the internal pressure of the secondary battery 100 exceeds a threshold value, and connect the central hole 157 and the through hole 154 in the radial direction of the secondary battery 100. The second fragile portion 158 may have various forms, such as a notch, thinned portion, or lightening portion structure disposed between the through-hole 154 and the central hole 157. The lightening portion structure may be one or more diamond-shaped holes, oval holes, circular holes, rectangular holes, etc., but is not limited thereto, as long as it can weaken the strength of the connection between the through-hole 154 and the central hole 157 and rupture when the internal pressure of the secondary battery 100 exceeds a threshold. After the second fragile portion 158 ruptures, communication between the central hole 157 and the through-hole 154 is achieved, and the current collector body 151 is divided into several thin pieces. Under the impact of internal pressure, each thin piece in the middle of the current collector body 151 folds back in a direction away from the electrode member 120, further reducing the obstruction area and contributing to the release of internal materials of the secondary battery, thereby contributing to preventing explosion of the secondary battery 100 and improving the safety performance of the secondary battery 100.

[0054] In one embodiment of the secondary battery 100 of the present invention, referring to FIGS. 3 and 4, the current collecting member 150 in this embodiment includes four case connecting portions 152 and four tab connecting portions 153, the four tab connecting portions 153 are uniformly distributed in a circumferential array along the circumferential direction of the current collecting body 151, and one case connecting portion 152 is provided between each two adjacent tab connecting portions 153 along the circumferential direction of the current collecting body 151, and one through hole 154 is provided between each two adjacent tab connecting portions 153, the shape of the through hole 154 resembles a vase shape with a relatively narrow middle, and the through hole 154 has a relatively large trapezoidal portion near the center hole 157, a hyperbolic portion avoiding the notch 156, and a relatively small trapezoidal portion near the case connecting portion 152. The first connecting portion 155 has a U-like shape under the combined influence of the notch 156 and the shape of the through hole 154. The first connecting portion 155 has a relatively large length and a relatively small width, and is easily deformed under bending stress. A second weakened portion 158 is provided between each through hole 154 and the central hole 157. The second weakened portion 158 has an elliptical shape, and the long side of the ellipse can connect the through hole 154 and the central hole 157. When the internal pressure reaches a threshold, the second weakened portion 158 can break to connect the central hole 157 and the through hole 154.

[0055] 5 to 8, the second embodiment of the secondary battery 100 of the present invention differs from the first embodiment in that the through-hole 154 lacks a trapezoidal portion near the case connection portion 152, and the notch 156 is enlarged toward one side near the tab connection portion 153 based on the first embodiment and has a fan-shaped configuration. This configuration does not significantly change the length of the first connection portion 155, but because the through-hole 154 in the trapezoidal portion near the case connection portion 152 is reduced, the area of ​​the straight portion 1522 is increased. This allows a first weak portion 1523 to be formed in the straight portion 1522, thereby reducing the transmission of bending stress to the inside of the current collector body 151. Preferably, in this embodiment, the first weak portion 1523 is formed as a thin-walled structure, and the opening 113 of the groove 1524 formed by the thin-walled structure faces one side of the electrode member 120. This configuration reduces the transmission of bending stress and also reduces the risk of fracture at the first weak portion 1523.

[0056] 9 and 10, the third embodiment of the secondary battery 100 of the present invention is different from the first embodiment in that the shape of the through hole 154 is different. The through hole 154 includes a triangular portion close to the center hole 157 and a rectangular portion close to the case connection portion 152. The through hole 154 of this configuration has an increased area and better pressure release and heat dissipation effects. Although no notch 156 is provided between the straight portion 1522 and the tab connection portion 153, the increased size of the through hole 154 still has the effect of making the first connection portion 155 more susceptible to deformation. Although the second weak portion 158 is not provided between the central hole 157 and the through hole 154, the portion close to the central hole 157 is a triangular apex, and the distance between the through hole 154 and the edge of the central hole 157 is smaller than in the first embodiment, so that when the internal pressure of the secondary battery 100 reaches a threshold value, the portion between the through hole 154 and the central hole 157 still easily tears, thereby connecting the central hole 157 and the through hole 154.

[0057] 11 , the present invention further provides a battery pack 10, which includes any of the secondary batteries 100 described above. In one embodiment of the battery pack 10 of the present invention, the battery pack 10 includes a case 101, a case lid 102, and a plurality of secondary batteries 100, which are arranged in the case 101 and connected in series, parallel, or a combination of series and parallel. The case lid 102 covers the case 101 to provide protection for the plurality of secondary batteries 100. It should be noted that the battery pack 10 may include not only the secondary battery 100 of the present invention but also other components such as a thermal management system for the battery pack 10, a circuit board, etc., and the battery pack 10 may be a battery module, a battery pack, a storage cabinet, etc., which will not be described in detail here.

[0058] Referring to FIG. 12 , the present invention further provides an electronic device 1, which includes the above-mentioned battery pack 10. A working unit 11 is electrically connected to the battery pack 10 to obtain power support. In one embodiment, the electronic device 1 is a vehicle, which may be a fuel-powered vehicle, a gas-powered vehicle, or a new energy vehicle. The new energy vehicle may be, but is not limited to, a pure electric vehicle, a hybrid vehicle, or a step-up vehicle. The working unit 11 is a vehicle body, and the battery pack 10 is installed at the bottom of the vehicle body and provides power support for the vehicle's running or the operation of internal electrical components. However, in some other embodiments, the electronic device 1 may also be a mobile phone, a portable device, a laptop, a boat, an aircraft, an electric toy, an electric tool, or the like. Aircraft include airplanes, rockets, space shuttles, and spacecraft. The working unit 11 may be a unit component that can obtain power from the battery pack 10 and perform a corresponding operation, such as a fan blade rotation unit or a vacuum cleaner dust collection unit. Electric toys include stationary and mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys. The power tools include metal cutting power tools, grinding power tools, assembly power tools, and railroad power tools, such as electric drills, electric grinding machines, electric wrenches, electric screwdrivers, electric hammers, electric impact drills, concrete vibrators, and electric planes. The embodiments of the present invention do not impose any particular limitations on the above-mentioned electronic device 1.

[0059] In the secondary battery of the present invention, a case connection portion is located between two adjacent tab connection portions along the circumferential direction of the case, and the case connection portions and the tab connection portions are arranged alternately in the circumferential direction of the case. This arrangement prevents bending stress from directly acting on the tab connection portion when it is transmitted to the current collector body when the case connection portion is bent, thereby reducing the bending stress transmitted to the tab connection portion. Through holes are provided between two adjacent tab connection portions, and a first connection portion is formed between each tab connection portion and the straight portion. The presence of the through holes reduces the width of the first connection portion, thereby reducing the bending stress transmitted to the tab connection portion. By absorbing partial bending stress through deformation, the transmission of bending stress to the tab connection portion is further reduced, and the problem of weld failure between the current collecting member and the tab due to bending stress is further reduced. Therefore, the present invention effectively overcomes some practical problems in the prior art and has great utility and significance. The above-described embodiments are intended to illustratively illustrate the principles and effects of the present invention and are not intended to limit the present invention. Those skilled in the art may make modifications or variations to the above-described embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations that can be accomplished by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be included in the claims of the present invention. [Industrial Applicability]

[0060] The secondary battery, battery pack and electronic device of the present invention can be applied in the field of battery technology. [Explanation of symbols]

[0061] 1:Electronic equipment 10: Battery pack 11:Working section 101: Box body 102: Box lid 100: Secondary battery 110: Case 111: End wall 112: Side wall 113:Aperture 114: Rolling groove 1141: First side wall 1142: Second side wall 120: Electrode member 121: Positive electrode sheet 1211: Positive electrode current collector 1212: 1st application area 1213: 1st uncoated area 122: Separator 123: Negative electrode sheet 1231: Negative electrode current collector 1232:Second application area 1233: 2nd uncoated area 124: Negative electrode tab 125: Positive electrode tab 130: Cover plate 140: Polar pillar 150: Current collecting member 151: Current collector body 152: Case connection part 1521: Bending part 1522:Straight section 1523: First weak spot 1524: Groove 153: Tab connection 154:Through hole 155: First connection part 156: Notch 157: Center hole 158: Second weak part

Claims

1. a case including an annular side wall, an opening formed at one end of the side wall, and an end of the side wall close to the opening including a rolling groove recessed toward the inside of the case; an electrode member housed within the case and including a tab facing the opening; a current collecting member including a current collecting body and a plurality of case connection portions annularly connected to an outer peripheral edge of the current collecting body, the current collecting body including a plurality of tab connection portions fixedly connected to the tabs, the case connection portions including a bent portion bent toward an axis of the case and a straight portion connected to the current collecting body, the bent portion being welded to a surface of the rolling groove facing the electrode member; Including, a case connection portion located between two adjacent tab connection portions along a circumferential direction of the case, a through hole being provided between the two adjacent tab connection portions, and a first connection portion being formed between each tab connection portion and the straight portion.

2. The secondary battery according to claim 1 , wherein a notch is provided between the straight portion and the tab connection portion, and the first connection portion is located between the notch and the through hole.

3. 3. The secondary battery according to claim 2, wherein a>s is satisfied, where a is the sum of the minimum current passing areas of all the first connection portions and s is the total area of ​​the weld lines formed by welding the tab connection portions and the tabs.

4. The secondary battery according to claim 1 , wherein the straight portion includes a first weak portion.

5. The secondary battery according to claim 4 , wherein the first fragile portion includes one or a combination of a thin portion, a notch, and a hollowed-out portion.

6. 6. The secondary battery according to claim 5, wherein b is the sum of the minimum current passing areas of all the first weak parts, and s is the total area of ​​the weld line formed by welding the current collector body and the tab, and b>s.

7. The secondary battery according to claim 5, wherein the thin portion and the notch are both grooves formed in the straight portion, and the grooves are located on the side of the collector body facing the electrode member.

8. The secondary battery of claim 1, characterized in that a central hole is provided at the center of the collector body, a second weak portion is included between each of the through holes and the central hole, and the second weak portion is configured to rupture when the internal pressure of the secondary battery exceeds a threshold value, thereby connecting the central hole and the through hole in the radial direction of the secondary battery.

9. A battery pack comprising the secondary battery according to any one of claims 1 to 8.

10. An electronic device comprising the battery pack according to claim 9.

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