Secondary batteries, battery packs, and electronic devices

Abstract

Provided are a secondary battery, a battery pack, and an electronic device that can improve the technical problem of welding failure between a current collecting member and a tab occurring easily during the 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 sidewall with an opening at one end and a rolling groove at one end of the sidewall closest to the opening. The electrode member is housed in the case and includes a tab facing the opening. The current collecting member includes a current collecting body and multiple case connection portions annularly connected to the outer periphery of the current collecting body. The current collecting body includes multiple tab connection portions fixedly connected to the tabs. The case connection portions include bent portions and straight portions connected to the current collecting body, and the bent portions are welded to the surface of the rolling groove facing the electrode member. Along the circumferential direction of the case, the case connection portions are located between adjacent two tab connection portions, and 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.

Description

Technical Field

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

Background Art

[0002] Mechanical sealing is the mainstream packaging method for conventional cylindrical batteries. Since it has the advantages of mature processes and equipment and a fast production tact, it is widely applied. In conventional cylindrical batteries, a current collector member is usually installed near the opening of the case. One end of the current collector member is welded and connected to the side wall of the case, and the other end is electrically connected to the tab of the electrode member, further realizing the electrical connection between the case and the electrode member, and then mechanical sealing is performed. This includes rolling a rolling groove recessed toward the inside of the case on the side wall of the case, and further crimping the cover plate by a driving and sealing method. In this process, due to the bending stress generated by the current collector member, the inside of the current collector member warps upward, and the welding location between the current collector member and the tab is torn, resulting in a risk of electrical connection failure of the electrode member.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In view of the above drawbacks of the prior art, the present invention provides a secondary battery, a battery pack, and an electronic device that improve the technical problem that the welding failure between the current collector member and the tab easily occurs during the mechanical sealing process of a cylindrical battery.

Means for Solving the Problems

[0004] To achieve the above-mentioned objectives and other related objectives, the present invention provides a secondary battery comprising: a case including an annular side wall, with an opening formed at one end of the side wall, and a rolling groove recessed toward the interior of the case at the end of the side wall near the opening; an electrode member housed within the case and including a tab facing the opening; and a current collector 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 a plurality of tab connection portions fixedly connected to the tab, the case connection portion includes a bent portion bending toward the axis of the case and a straight portion connected to the current collector body, the bent portion being welded to the surface of the rolling groove facing the electrode member, and along the circumferential direction of the case, the case 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.

[0005] In the above-described technical proposal, the case connection portion is located between two adjacent tab connection portions along the circumferential direction of the case, and the case connection portion and tab connection portion are installed alternately along the circumferential direction of the case. This arrangement makes it possible to reduce the transmission of bending stress to the tab connection portion when the case connection portion bends, as the bending stress is transmitted toward the current collector body without directly acting on the tab connection portion.

[0006] In addition, a through-hole is provided between two adjacent tab connections, and a first connection is formed between each tab connection and the straight section. The presence of the through-hole reduces the width of the first connection, thereby weakening the bending stress transmitted toward the tab connection. At the same time, by weakening the strength of the first connection, it becomes more easily deformed under the action of bending stress, absorbing partial bending stress and further weakening the transmission of bending stress to the tab connection, thereby improving the problem of weld failure between the current collector 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 section and the tab connection section, and the first connection section is located between the notch and the through-hole.

[0008] In the above-described technical proposal, the installation of notches further reduces the strength of the first connection, making it more deformable and allowing it to absorb more stress, ultimately further weakening the transmission of bending stress to the tab connection.

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

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

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

[0012] In the above-described technical proposal, by installing a first weak point in the straight section, the stress generated when the case connection section is bent can be reduced. At the same time, because the strength of the first weak point is low, under the action of stress, the first weak point in the straight section will deform first, reducing the transmission of stress to the welded connection part between the current collector and the tab, and thereby improving the problem of weld failure between the current collector and the tab due to bending stress.

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

[0014] In the above-described technical proposal, any combination of one or more of the thin-walled sections, notches, and hollowed-out sections can reduce the strength of the first weak point by decreasing the cross-sectional area of ​​the first weak point.

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

[0016] In the above-described technical proposal, the minimum current-passing area of ​​the first weak point is the smallest point of the cross-sectional area along the circumferential direction of the current-collecting member of each first weak point, and the total area of ​​the weld line refers to the area of ​​the projection along the axial direction of the electrode member of all the weld lines themselves that are formed by welding the tab connection part and the tab. By installing an area where the sum b of the minimum current-passing areas of all first weak points is larger than the total area of ​​the weld line, it is possible to weaken the transmission of bending stress while simultaneously not affecting the current-carrying effect of the first weak point.

[0017] In one embodiment of the secondary battery of the present invention, both the thin-walled portion and the notch 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-described technical proposal, the bending stress generated at the case connection causes the tab connection to warp, and similarly, the first weak point in the straight section also tends to bulge 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 point fracturing when it bulges. Therefore, by installing the groove on the side of the current collector body facing the electrode member, the transmission of bending stress can be weakened, and at the same time, the risk of fracture at the first weak point can be reduced.

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

[0020] In the above-described technical proposal, when the internal pressure exceeds a threshold, the second weak point ruptures, the central hole and the through-hole communicate, the current collector body separates into multiple thin segments, and under the impact of the internal pressure, each thin segment in the middle of the current collector body folds back toward the electrode member, further reducing the obstruction area and contributing to the discharge of internal materials of the secondary battery, thereby contributing to the prevention of explosion of the secondary battery and improving the safety performance of the secondary battery.

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

[0022] The present invention also provides an electronic device including the battery pack described above. [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 portion and the tab connection portion are installed alternately in the circumferential direction of the case. This installation makes it possible to reduce the bending stress transmitted to the tab connection portion when the case connection portion bends, as the bending stress is transmitted to the current collector body without directly acting on the tab connection portion.

[0024] In addition, a through-hole is provided between two adjacent tab connections, and a first connection is formed between each tab connection and the straight section. The presence of the through-hole reduces the width of the first connection, thereby weakening the bending stress transmitted to the tab connection. At the same time, the weakened strength of the first connection makes it easier for the first connection to deform under the action of bending stress, absorbing partial bending stress and further weakening the transmission of bending stress to the tab connection, ultimately improving the problem of welding failure between the current collector and the tab due to bending stress. [Brief explanation of the drawing]

[0025] To more clearly illustrate 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. Naturally, the drawings in the following description are only some embodiments of the present invention. A person skilled in the art can obtain other embodiments based on these drawings without creative efforts. [Figure 1] It is an overall structure explanatory diagram of an embodiment of the secondary battery of the present invention. [Figure 2] It is a structure explanatory diagram of an electrode member of an embodiment of the secondary battery of the present invention. [Figure 3] It is a structure explanatory diagram of a current collector member before bending in an embodiment of the secondary battery of the present invention. [Figure 4] It is a top view of the current collector member shown in FIG. 3. [Figure 5] It is a structure explanatory diagram of a current collector member before bending in the second embodiment of the secondary battery of the present invention. [Figure 6] It is a partial enlarged view of portion A in FIG. 5. [Figure 7] It is a top view of the current collector member shown in FIG. 5. [Figure 8] It is a bottom view of the current collector member shown in FIG. 5. [Figure 9] It is a structure explanatory diagram of a current collector member before bending in the third embodiment of the secondary battery of the present invention. [Figure 10] It is a top view of the current collector member shown in FIG. 9. [Figure 11] It is an explanatory diagram of an embodiment of the battery pack of the present invention. [Figure 12] It is an explanatory diagram of an embodiment of the electronic device of the present invention.

Embodiments for Carrying Out the Invention

[0026] The following describes implementations of the present invention by specific embodiments, so that those skilled in the art can easily understand other advantages and effects of the present invention from what is disclosed herein. The present invention can be implemented or applied in yet another different specific embodiment, and the details of each item herein can be modified or changed in various ways based on different perspectives and applications without departing from the spirit of the invention. Where there is no inconsistency, the following embodiments and features within them can be combined with each other. It should also be understood that the terms used in the embodiments of the present invention are for describing specific specific implementations and are not intended to limit the scope of protection of the present invention. In the embodiments below, test methods where specific conditions are not specified are usually carried out according to general conditions or according to conditions recommended by each manufacturer.

[0027] In these embodiments, when numerical ranges are indicated, it should be understood that, unless otherwise stated in the present invention, any numerical values ​​can be selected at both endpoints of each numerical range and between those endpoints. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those understood by the articulate person to the existing art and as described in the present invention, and the present invention can be realized using any existing methods, equipment and materials that are similar or equivalent to the methods, equipment and materials described in the embodiments of the present invention.

[0028] Furthermore, terms such as "up," "down," "left," "right," "middle," and "one" used herein are merely for the purpose of clarifying the description and do not limit the scope within which the present invention can be implemented. Any changes or adjustments to their relative relationships are considered to fall within the scope within which the present invention can be implemented, provided that there is no substantial change in the technical content.

[0029] A secondary battery includes electrode members, which are components that generate electrochemical reactions in the secondary battery, and may include one or more electrode members.

[0030] The secondary battery further includes a case, a cover plate, and electrode posts. The case includes end walls and side walls surrounding the end walls, one end of which has an opening. Electrode members can be assembled inside the case through the opening. The cover plate is used to cover the opening in the case and achieve sealing. Electrode posts penetrate the end walls and are electrically connected to the electrode members, deriving the power generated by the electrode members.

[0031] The mainstream sealing method for conventional secondary batteries is mechanical sealing. Mechanical sealing has the advantages of a mature process and equipment, and a fast production cycle, and is widely applied. The current collector is electrically connected to the electrode member and the case simultaneously, achieving an electrical connection between the electrode member and the case. Specifically, a rolling groove is first rolled around the case sidewall, recessed toward the inside of the case. The side of the rolling groove closest to the electrode member presses against the edge of the current collector. The rolling groove can limit the axial displacement of the electrode member. The cover plate is placed on a step formed on the side of the rolling groove away from the electrode member. A sealing member is placed between the cover plate and the case. Furthermore, a press-fit sealing method is adopted at the edge of the opening to press the sealing member against the cover plate, forming a reliable connection and achieving case sealing.

[0032] There are various methods for connecting current collectors to cases. One commonly used method involves installing a case connection section on the edge of the current collector, first welding the case connection section to the side wall of the case, and then rolling a groove onto the side wall to continuously bend the case connection section toward the axis of the case. However, the inventor discovered that when the case connection section bends toward the axis of the case, bending stress is generated, which is further transmitted into the current collector, causing the inside of the current collector to warp, which tears the welded area between the current collector and the tab, and thus creating a risk of loss of electrical connection of the electrode member.

[0033] In view of this, the present invention provides a technical solution in which the case connection portion and the tab connection portion are installed alternately in the circumferential direction of the case, and by this installation, when the case connection portion bends, the bending stress is transmitted toward the current collector body and does not directly act on the tab connection portion, thereby reducing the bending stress transmitted toward the tab connection portion and further improving the problem of welding failure between the current collector member and the tab due to bending stress.

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

[0035] Referring to Figure 1, the case 110 includes an end wall 111 and a side wall 112 surrounding the end wall 111. The connection between the end wall 111 and the side wall 112 can be achieved in various ways, as long as a stable seal and an electrically connected relationship can be formed, for example, by integral press molding, integral casting, or partial welding. The surrounding shape of the side wall 112 is not limited and can surround the end wall 111 in a cylindrical or prismatic shape, or it can surround the end wall 111 in any other closed loop shape that is compatible with it. In this embodiment, the outer edge of the end wall 111 is circular, and the side wall 112 surrounds the outer edge of the end wall 111 in a cylindrical shape, with a circular opening 113 formed at one end of the side wall 112 away from the end wall 111. A housing chamber is formed inside the case 110 surrounded by the end wall 111 and the side wall 112, and is used to house the electrode member 120, electrolyte, and other necessary battery components. Specifically, the diameter of the case 110 can be determined based on the specific dimensions of the electrode member 120, and can be 18 mm, 21 mm, 46 mm, etc. The material of the case 110 can vary, for example, copper, iron, aluminum, steel, aluminum alloy, etc., and in order to prevent the case 110 from rusting during long-term use, an additional layer of rust-preventive material such as metallic nickel may be plated onto the surface of the case 110.

[0036] Referring to Figures 1 and 2, the electrode member 120 is installed inside the case 110, and the electrode member 120 is a component that undergoes an electrochemical reaction 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 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] Referring to Figures 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 on the positive electrode current collector 1211 is formed where the positive electrode active material layer is coated, and a first uncoated region 1213 is formed where the positive electrode active material layer is not coated. The first coated region 1212 and the first uncoated region 1213 are arranged along the axial direction of the case 110, and the first uncoated region 1213 extends out of the separator 122 toward one end in the height direction of the secondary battery 100, forming a positive electrode tab 125 that is bent toward the axis of the case 110 and stacked.

[0038] Referring to Figures 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 on the negative electrode current collector 1231 is formed where the negative electrode active material layer is coated, and a second uncoated region 1233 is formed where the negative electrode active material layer is not coated. The second coated region 1232 and the second uncoated region 1233 are arranged along the axial direction of the case 110, and the second uncoated region 1233 extends out of the separator 122 toward the other end in the height direction of the secondary battery 100, forming a negative electrode tab 124 that is bent toward the axis of the case 110 and stacked.

[0039] Referring to Figures 1 and 2, the separator 122 is placed between the positive electrode sheet 121 and the negative electrode sheet 123, separating the positive electrode active material layer from the negative electrode active material layer. Taking the battery 100 as a lithium-ion secondary battery as an example, the material of the positive electrode current collector 1211 may be aluminum, and the positive electrode active material layer contains a positive electrode active material, which may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The material of the negative electrode current collector 1231 may be copper, and the negative electrode active material layer contains a negative electrode active material, which may be carbon or silicon. The substrate material of the separator 122 may be polypropylene (PP) or polyethylene (PE), etc. To provide protection and insulation to the battery cell, an insulating film can be applied to the outside of the battery cell. This insulating film can be synthesized from PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC), or other polymer materials.

[0040] Referring to Figures 1 and 2, further, in the present invention, when the positive electrode tab 125 faces either the end wall 111 or the opening 113, the negative electrode tab 124 faces the other end of the case 110. In this embodiment, the positive electrode tab 125 faces the end wall 111 and electrically connects with the pole column 140, making the pole column 140 positively charged, while the negative electrode tab 124 faces the opening 113 and becomes negatively charged when the case 110 and the negative electrode tab 124 are electrically connected. However, in other embodiments, the negative electrode tab 124 may be connected to the pole column 140, and the positive electrode tab 125 may be connected to the case 110.

[0041] Referring to Figure 1, the cover plate 130 is sealed into the opening 113. The outer edge shape 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 machined all the way around the side wall 112 of the case 110, recessed toward the inside of the case 110, in an area near the outer end of the side wall 112. 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 restrict the axial displacement of the electrode member 120. The second side wall 1142 surrounds the case 110 in an annular shape on the side away from the rolling groove 114, forming an annular step. The cover plate 130 is placed on this step, a seal ring is installed between the cover plate 130 and the annular groove 1121, and the edge of the opening 113 employs a press-fit sealing method so that the cover plate 130 presses against the seal ring, forming a reliable connection.

[0042] Referring to Figures 1 and 2, the pole post 140 is fixed to the end wall 111 and electrically connected to the electrode member 120. Specifically, a pole post hole is provided in the end wall 111, and the pole post 140 is installed by penetrating through the pole post hole and insulated from the end wall 111. One end of the pole post 140 facing the electrode member 120 penetrates the end wall 111 and is electrically connected directly to the positive electrode tab 125, or is electrically connected by indirect transfer contact. The structural form of the pole post 140 can be any suitable form that penetrates the end wall 111 and is electrically connected to the positive electrode tab 125 of the electrode member 120. For example, the cross-section can be circular, square, prismatic, or an irregular contour that can achieve stable conductivity. The shape of the pole post hole and the pole post 140 correspond, and in this embodiment, the cross-section of the pole post 140 is circular.

[0043] Referring to Figure 1, the current collector 150 is installed 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 collector 150. Specifically, the current collector 150 includes a current collector body 151 and a case connection portion 152 connected to the outer periphery of the current collector body 151. The case connection portion 152 may be a single annular structure or one or more fan-shaped annular structures, as long as it satisfies the current guidance requirements and welding strength requirements between the current collector 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 current 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. Simultaneously with 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, finally forming a shape that bends 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] Referring to Figures 3 to 5, 7 and 10, the current collector body 151 is fixedly connected to the tabs. There are various methods for connecting the current collector body 151 to the tabs, such as welding or conductive adhesive. As long as an electrical connection is achieved between the current collector 150 and the tabs and the current guidance requirements are met, the current collector body 151 is fixedly connected to the tabs. In this embodiment, the welding method is adopted. Furthermore, the current collector body 151 includes a plurality of tab connection parts 153 that are welded to the tabs. The number, shape and position of the tab connection parts 153 are not limited. Preferably, in this embodiment, the current collector body 151 includes four tab connection parts 153 that are welded to the tabs. The four tab connection parts 153 are evenly arranged along the circumferential direction of the current collector body 151. This arrangement improves the welding balance stability between the current collector 150 and the tabs and provides a more uniform current guidance effect, thereby improving the stability of current guidance between the case 110 and the electrode member 120.

[0045] When the case connection portion 152 bends toward the axis of the case 110, bending stress is generated, and this bending stress is transmitted to the inside of the current collector member 150, further causing the technical problem of internal warping of the current collector member 150. Referring to Figures 3 to 5, 7 and 10, the case connection portion 152 is positioned between two adjacent tab connection portions 153 along the circumferential direction of the case 110, and the case connection portion 152 and the tab connection portion 153 are installed alternately in the circumferential direction of the case 110. This installation prevents the bending stress from directly acting on the tab connection portion 153 when the case connection portion 152 bends and is transmitted to the current collector body 151, thereby weakening the transmission of bending stress to the tab connection portion 153.

[0046] Referring to Figures 3-5, 7, and 10, a through-hole 154 is provided between two adjacent tab joints 153. The shape of the through-hole 154 is not limited and may be circular, square, sector-shaped, rhombus-shaped, or other irregular shape. A first joint 155 is formed between each tab joint 153 and the straight section 1522. The shape of the first joint 155 depends on the shape of the through-hole 154. The presence of the through-hole 154 reduces the width of the first joint 155, weakening the bending stress transmitted to the tab joint 153. At the same time, the weakening of the strength of the first joint 155 makes it easier for the first joint 155 to deform under the action of bending stress, absorbing partial bending stress and further weakening the transmission of bending stress to the tab joint 153. This improves the problem of weld failure between the current collector 150 and the tab due to bending stress.

[0047] Referring to Figures 3-5, 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 can be varied, for example, rectangular, sector-shaped, or other irregular shapes. The provision of the notch 156 makes it possible to further reduce the strength of the first connection portion 155, making it more deformable and absorbing more stress, and ultimately further weakening the transmission of bending stress to the tab connection portion 153.

[0048] Referring to Figures 3 to 5, 7 and 10, in one embodiment of the secondary battery 100 of the present invention, let a be the sum of the minimum current passage areas of all first connection parts 155, and let s be the total area of ​​the weld lines formed by welding the tab connection part 153 and the tab, where a > s. The minimum current passage area of ​​the first connection part 155 is the smallest point of the cross-sectional area of ​​each first connection part 155 along the circumferential direction of the current collector member 150, and the total area of ​​the weld lines refers to the projected area of ​​all the weld lines themselves formed by welding the tab connection part 153 and the tab along the axial direction of the electrode member 120. By setting the sum a of the minimum current passage areas of all first connection parts 155 to be greater than the total area of ​​the weld lines, it is possible to weaken the transmission of bending stress while simultaneously not affecting the current-carrying effect of the first connection part 155.

[0049] Referring to Figures 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 configuration reduces the stress generated when the case connection portion 152 bends, and at the same time, because the strength of the first weak portion 1523 is low, under the action of stress, the first weak portion 1523 of the straight portion 1522 deforms first, reducing the transmission of stress to the welded connection portion between the current collector member 150 and the tab, and further improving the problem of welding failure between the current collector member 150 and the tab due to bending stress.

[0050] Referring to Figures 5 to 8, in one embodiment of the secondary battery 100 of the present invention, the first weak portion 1523 includes one or more combinations of thin-walled portions, notches, and hollowed-out portions. In some embodiments, only thin-walled portions, notches, or hollowed-out portions are provided, while in other embodiments, a combination of thin-walled portions and hollowed-out portions, or a combination of notches and hollowed-out portions, can 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 the 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] Referring to Figures 5 to 8, in one embodiment of the secondary battery 100 of the present invention, let b be the minimum current passage area of ​​all first weak parts 1523, and let s be the total area of ​​the weld lines formed by welding the current collector body 151 and the tab, where b > s. The minimum current passage area of ​​the first weak parts 1523 is the smallest point of the cross-sectional area along the circumferential direction of the current collector member 150 of each first weak part 1523, and the total area of ​​the weld lines refers to the projected area along the axial direction of the electrode member 120 of all the weld lines themselves formed by welding the tab connection part 153 and the tab. By setting the sum b of the minimum current passage areas of all first weak parts 1523 to be greater than the total area s of the weld lines, it is possible to weaken the transmission of bending stress while simultaneously not affecting the current-carrying effect of the first weak parts 1523.

[0052] Referring to Figures 5 to 8, in one embodiment of the secondary battery 100 of the present invention, both the thin-walled portion and the notch form grooves 1524 in the straight portion 1522. Considering that the bending stress generated in the case connection portion 152 causes the tab connection portion 153 to warp, similarly, the first weak portion 1523 of the straight portion 1522 also tends to bulge away from the electrode member 120. If the groove 1524 is located on one side of the current collector body 151 away from the electrode member 120, there is a risk of the first weak portion 1523 fracturing when it bulges. Preferably, in this embodiment, the groove 1524 is located on one side of the current collector body 151 facing the electrode member 120. This arrangement weakens the transmission of bending stress and simultaneously reduces the risk of fracture at the first weak portion 1523.

[0053] Referring to Figures 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 rhombic hole, a polygonal hole or other irregularly closed contour hole, a second weak portion 158 is included between each through hole 154 and the central hole 157, the second weak portion 158 ruptures when the internal pressure of the secondary battery 100 exceeds a threshold, and the central hole 157 and the through hole 154 rupture radially in the secondary battery 100 The second weak point 158 ​​is configured to communicate with the through-hole 154 and the central hole 157, and can take various forms. For example, it may be a notch, a thin-walled section, or a hollowed-out section structure installed between the through-hole 154 and the central hole 157. The hollowed-out section structure may be one or more rhombic holes, elliptical holes, circular holes, or rectangular holes, and is not limited thereto. It is sufficient that 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 weak point 158 ​​ruptures, communication between the central hole 157 and the through-hole 154 is achieved, the current collector body 151 is divided into several thin pieces, and 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 discharge of internal materials of the secondary battery, thereby contributing to preventing the secondary battery 100 from exploding 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 Figures 3 to 4, the current collector member 150 in this embodiment includes four case connection portions 152 and four tab connection portions 153, the four tab connection portions 153 are evenly distributed in a circular arrangement along the circumferential direction of the current collector body 151, and along the circumferential direction of the current collector body 151, one case connection portion 152 is provided between each of two adjacent tab connection portions 153, and one through-hole 154 is provided between each of two adjacent tab connection portions 153, the shape of the through-hole 154 resembles a vase shape that is relatively narrow in the middle, and the through-hole 154 has a relatively large trapezoidal portion close to the central hole 157, a hyperbolic portion that avoids the notch 156 and a relatively small trapezoidal portion close to the case connection portion 152 The structure includes a portion, with a notch 156 provided between each straight section 1522 and each tab connection section 153, the notch 156 being a rectangular opening 113, the first connection section 155 forming a U-like shape under the combined influence of the notch 156 and the shape of the through-hole 154, the first connection section 155 being relatively long and relatively narrow in width, and deforming more easily under the action of bending stress, a second weak point 158 ​​provided between each through-hole 154 and the central hole 157, the shape of the second weak point 158 ​​being an elliptical hole, the extension of the long side of the ellipse being able to connect the through-hole 154 and the central hole 157, and when the internal pressure reaches a threshold, it can split and allow the central hole 157 and the through-hole 154 to communicate.

[0055] In a second embodiment of the secondary battery 100 of the present invention, referring to Figures 5 to 8, the difference between this embodiment and the first embodiment is that the through-hole 154 lacks a trapezoidal portion near the case connection portion 152, the notch 156 is enlarged toward one side near the tab connection portion 153 on the base of the first embodiment, and its shape is fan-shaped. This installation does not significantly change the length of the first connection portion 155, but because the number of through-holes 154 in the trapezoidal portion near the case connection portion 152 is reduced, the area of ​​the straight portion 1522 is increased, and therefore the first weak portion 1523 can be installed in the straight portion 1522, thereby weakening the transmission of bending stress into the current collector body 151. Preferably, in this embodiment, the first weak portion 1523 is installed 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 installation weakens the transmission of bending stress and simultaneously reduces the risk of fracture at the first weak portion 1523.

[0056] In a third embodiment of the secondary battery 100 of the present invention, referring to Figures 9 to 10, the difference between this embodiment and the first embodiment is that the shape of the through-hole 154 is different. The through-hole 154 includes a triangular portion near the central hole 157 and a rectangular portion near the case connection portion 152. With this configuration, the area of ​​the through-hole 154 is increased, resulting in better pressure release and heat dissipation effects. Although there is no notch 156 between the straight portion 1522 and the tab connection portion 153, the larger through-hole 154 still makes the first connection portion 155 more susceptible to deformation. Although a second weak point 158 ​​is not provided between the central hole 157 and the through-hole 154, the portion closest to the central hole 157 is a triangular point, and the distance between the through-hole 154 and the edge of the central hole 157 is smaller than that of the first embodiment. Therefore, when the internal pressure of the secondary battery 100 reaches a threshold, the space between the through-hole 154 and the central hole 157 still easily tears, creating a connection between the central hole 157 and the through-hole 154.

[0057] Referring to Figure 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 casing 101, a casing lid 102, and a plurality of secondary batteries 100, which are arranged in the casing 101 and connected to each other in series, parallel, or a combination of series and parallel. The casing lid 102 is placed over the casing 101 to cover and protect the plurality of secondary batteries 100. It should be noted that the battery pack 10 may include parts other than the secondary batteries 100 of the present invention, such as a thermal management system and a circuit board. The battery pack 10 may also be a battery module, a battery pack, or a power storage cabinet, etc., which will not be described in detail individually here.

[0058] Referring to Figure 12, the present invention further provides an electronic device 1, which includes the battery pack 10 described above. A work 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 vehicle, or a new energy vehicle, and the new energy vehicle may be, but is not limited to, a pure electric vehicle, a hybrid vehicle, or an augmented-range vehicle. The work unit 11 is the vehicle body, and the battery pack 10 is installed at the bottom of the vehicle body to provide power support for the vehicle's movement or the operation of in-vehicle electrical components. However, in some other embodiments, the electronic device 1 may further be a mobile phone, a portable device, a laptop computer, a ship, an aircraft, an electric toy, and a power tool, etc. Aircraft include airplanes, rockets, space shuttles, and spacecraft, etc. The work unit 11 may be a unit member that can obtain power from the battery pack 10 and perform a corresponding task, such as a fan blade rotation unit or a vacuum cleaner dust collection work unit. 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 grinding machines, electric wrenches, electric screwdrivers, electric hammers, impact electric drills, concrete vibrators, and electric planers. Embodiments of the present invention do not impose any particular limitations on the electronic device 1 described above.

[0059] The secondary battery of the present invention has a case connection portion located between two adjacent tab connection portions along the circumferential direction of the case, and the case connection portion and tab connection portions are installed alternately in the circumferential direction of the case. This installation prevents bending stress from directly acting on the tab connection portion when the case connection portion bends and is transmitted toward the current collector body, thereby reducing the bending stress transmitted toward the tab connection portion. A through hole is provided between two adjacent tab connection portions, and a first connection portion is formed between each tab connection portion and a straight portion. The presence of the through hole reduces the width of the first connection portion, weakening the bending stress transmitted toward the tab connection portion, and further reducing the transmission of bending stress to the tab connection portion by absorbing partial bending stress through deformation, and further improving the problem of welding failure between the current collector member and tab due to bending stress. Therefore, the present invention effectively overcomes some of the practical problems of the prior art and has very high utility and significance. The above embodiments are illustrative in illustrating the principles and effects of the present invention and do not limit the present invention. Those skilled in the art can modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those skilled in the art without deviating 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: Work Unit 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 material 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 Tab 130: Cover plate 140: Polar pillar 150: Current collector 151: Current collector body 152: Case connection part 1521: Bending section 1522: Straight section 1523: First Vulnerable Point 1524: Groove 153: Tab connection section 154: Through-hole 155: First connection section 156: Notch 157: Center hole 158: Second Vulnerable Area

Claims

1. A case including an annular side wall, wherein an opening is formed at one end of the side wall, and the end of the side wall near the opening includes a rolling groove recessed toward the interior of the case, An electrode member housed within the case and including a tab facing the opening, A current collector member comprising a current collector body and a plurality of case connection portions connected annularly to the outer periphery of the current collector body, wherein the current collector body includes a plurality of tab connection portions fixedly connected to the tab, and the case connection portion includes a bent portion that bends toward the axis of the case and a straight portion that connects to the current collector body, and the bent portion is welded to the surface of the rolling groove facing the electrode member, the current collector member and, Includes, A secondary battery characterized in that, along the circumferential direction of the case, the case 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.

2. The secondary battery according to claim 1, characterized in that 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. The secondary battery according to claim 2, characterized in that a > s when the sum of the minimum current passage areas of all the first connection parts is a, and the total area of ​​the weld line formed by welding the tab connection part and the tab is s.

4. The secondary battery according to claim 1, characterized in that the straight portion includes the first vulnerable portion.

5. The secondary battery according to claim 4, characterized in that the first vulnerable portion includes one or more combinations of thin-walled portions, notches, and hollowed-out portions.

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

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

8. The secondary battery according to claim 1, characterized in that a central hole is provided in the center of the current collector body, a second weak point is included between each of the through-holes and the central hole, the second weak point ruptures when the internal pressure of the secondary battery exceeds a threshold, and the central hole and the through-hole are configured to communicate in the radial direction of the secondary battery.

9. A battery pack characterized by including a secondary battery according to any one of claims 1 to 8.

10. An electronic device characterized by including the battery pack described in claim 9.

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