Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a secondary battery, a battery pack and an electronic device, the secondary battery comprises a shell, an electrode assembly and a current collecting component, the shell comprises an end wall, and the end wall is provided with an anti-explosion valve; the electrode assembly is arranged in the shell, and one side, facing the end wall, of the electrode assembly is provided with a first tab; the current collecting component is arranged on one side, facing the end wall, of the electrode assembly and is electrically connected with the shell; the current collecting component comprises a plurality of tab connecting parts which are all welded with the first tab, and when the anti-explosion valve is opened, the current collecting component is turned over towards one side far away from the electrode assembly; a weak part is arranged between every two adjacent tab connecting parts, and the weak parts enable the adjacent tab connecting parts to be easily turned over when the anti-explosion valve is opened; the orthographic projection area of the anti-explosion valve is S, the projection area of the flow collecting component falling into the orthographic projection area of the anti-explosion valve is S1, and S1 is larger than or equal to 0.4 S and smaller than S. The technical problem that in the prior art, when the explosion-proof valve is opened, the tearing effect of the flow collecting component is poor can be solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a battery technical field, concretely relates to a secondary battery, battery pack and electronic device. BACKGROUND

[0002] Secondary batteries have been widely used in the automotive industry due to their high energy density and cost-effectiveness. Currently, mature secondary batteries are generally provided with explosion-proof valves to open and release the internal gas of the secondary battery when the internal pressure of the secondary battery rises to a warning value, thereby achieving pressure relief of the secondary battery and avoiding explosion of the secondary battery due to excessive pressure.

[0003] In existing secondary batteries, the explosion-proof valve is usually arranged at the end wall of the shell, and the end face position of the electrode assembly corresponding to the side of the end cover is usually provided with a current collecting member. When the explosion-proof valve is opened for pressure relief, the current collecting member needs to be torn to achieve rapid release of the internal pressure of the shell. However, the current collecting member structure in the prior art usually has poor tearing effect when the explosion-proof valve is opened, thereby affecting the pressure relief effect of the secondary battery and reducing the safety performance of the secondary battery. SUMMARY

[0004] The utility model provides a kind of secondary battery, battery pack and electronic device to improve the technical problem of poor tearing effect of current collecting member in prior art when explosion-proof valve is opened.

[0005] To achieve the above object and other related purposes, the utility model provides a kind of secondary battery, which comprises: a shell, an electrode assembly and a current collecting member, the shell comprises an end wall, and the end wall is provided with an explosion-proof valve; the electrode assembly is arranged in the shell, and the side of the electrode assembly facing the end wall has a first lug; the current collecting member is arranged on the side of the electrode assembly facing the end wall and electrically connected with the shell; the current collecting member comprises a plurality of lug connecting parts, the plurality of lug connecting parts are all welded with the first lug, and when the explosion-proof valve is opened, the lug connecting parts are folded towards the side away from the electrode assembly; along the circumferential direction of the current collecting member, a weak part is arranged between adjacent lug connecting parts, and the weak part makes the adjacent lug connecting parts easy to fold when the explosion-proof valve is opened; wherein, along the stacking direction of the end wall and the electrode assembly, the orthographic projection area of the explosion-proof valve is S, the projection area of the current collecting member falling into the orthographic projection area of the explosion-proof valve is S1, and 0.4S≤S1

[0006] In an example of the secondary battery of the utility model, the central region of the current collecting member is provided with a tearing part, one end of the weak part is arranged close to the center of the current collecting member, adjacent weak parts are connected through the tearing part, and the tearing part is torn when the explosion-proof valve is opened.

[0007] In the secondary battery example of the utility model, the center area of the current collecting component is provided with a through hole, the tearing part is arranged between the through hole and the weak part, and the through hole is connected with the weak part through the tearing part.

[0008] In the secondary battery example of the utility model, the tearing part comprises a tearing hole, the tearing hole is communicated with the through hole, and the tearing hole is located on the extension line of the weak part.

[0009] In the secondary battery example of the utility model, one end of the weak part is arranged close to the center of the current collecting component, and adjacent weak parts are communicated with each other close to the center of the current collecting component.

[0010] In the secondary battery example of the utility model, the center area of the current collecting component is provided with a through hole, the weak part is communicated with the through hole.

[0011] In the secondary battery example of the utility model, the positive projection profile formed by the explosion valve on the current collecting component is a circular profile, and one end of the weak part away from the center of the current collecting component extends to the outside of the positive projection profile.

[0012] In the secondary battery example of the utility model, the circumference of the positive projection profile is L; the arc length of the shortest circular arc between adjacent weak parts is L1, and L1 is less than or equal to 1 / 5 of L.

[0013] In the secondary battery example of the utility model, the positive projection profile formed by the explosion valve on the current collecting component is a circular profile; the weak part comprises a first weak part and a second weak part, one end of the first weak part is arranged close to the center of the current collecting component, and the other end is connected with the second weak part; the second weak part extends along the circumferential direction of the positive projection profile, and the positive projection profile penetrates the second weak part.

[0014] In the secondary battery example of the utility model, the positive projection profile formed by the explosion valve on the current collecting component is a circular profile; the weak part comprises a third weak part and two fourth weak parts, the third weak part is arranged close to the center of the current collecting component and extends along the radial direction of the current collecting component; the two fourth weak parts are arranged at one end of the third weak part away from the center of the current collecting component and are located on both sides of the extension line of the third weak part; each fourth weak part extends from one side close to the extension line of the third weak part to one side away from the extension line of the third weak part and extends to the outside of the positive projection profile.

[0015] In the secondary battery example of the utility model, the center of the current collecting component is provided with a tearing part, and the tearing part is torn when the explosion valve is opened; the weak part comprises a fifth weak part and two sixth weak parts, the fifth weak part penetrates the tearing part along the radial direction of the current collecting component, and the two sixth weak parts are arranged on both sides of the fifth weak part and connected with the tearing part.

[0016] In the secondary battery example of the utility model, the positive projection profile formed by the explosion-proof valve on the current collecting component is a circular profile; the weak part further comprises a second weak part, the second weak part is arranged at both ends of the fifth weak part and / or one end of the sixth weak part away from the center of the current collecting component; the second weak part extends along the circumference of the positive projection profile, and the positive projection profile penetrates the second weak part.

[0017] In the secondary battery example of the utility model, the weak part is a hollow structure.

[0018] The utility model further provides a battery pack, the battery pack includes the secondary battery of any one of above.

[0019] The utility model further provides an electronic device, the electronic device includes the battery pack of above.

[0020] In the secondary battery, the positive projection area of the explosion-proof valve is S, the projection area of the current collecting component falling into the positive projection area of the explosion-proof valve is S1, and 0.4S≤S1 BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other embodiments can be obtained according to these drawings without creative labor.

[0022] Figure 1 It is the overall structure sectional view of the secondary battery example of the utility model;

[0023] Figure 2 It is the overall structure sectional view of the secondary battery example of the utility model; Figure 1 It is the local sectional view of area A;

[0024] Figure 3 It is the structure schematic view of the explosion-proof valve arranged in the second end wall in the secondary battery example of the utility model;

[0025] Figure 4 Structure diagram of electrode assembly of a secondary battery according to the present application;

[0026] Figure 5 Structure diagram of a structure in which adjacent weak parts are connected through a tear part at the center position of the current collecting member in the electrode assembly of a secondary battery according to the present application;

[0027] Figure 6 Structure diagram of a structure in which a through hole is provided at the center of the current collecting member in the electrode assembly of a secondary battery according to the present application;

[0028] Figure 7 Structure diagram of a structure in which adjacent weak parts are communicated with each other at the center of the current collecting member in the electrode assembly of a secondary battery according to the present application;

[0029] Figure 8 Structure diagram of a structure in which adjacent weak parts are communicated with each other through a through hole at the center of the current collecting member in the electrode assembly of a secondary battery according to the present application;

[0030] Figure 9 Structure diagram of a structure in which the weak part includes a first weak part and a second weak part in the electrode assembly of a secondary battery according to the present application;

[0031] Figure 10 Structure diagram of a structure in which the weak part includes a first weak part and a second weak part in another example of the electrode assembly of a secondary battery according to the present application;

[0032] Figure 11 Structure diagram of a structure in which the weak part includes a third weak part and a fourth weak part in the electrode assembly of a secondary battery according to the present application;

[0033] Figure 12 Structure diagram of a structure in which the weak part includes a third weak part and a fourth weak part in another example of the electrode assembly of a secondary battery according to the present application;

[0034] Figure 13 Structure diagram of a structure in which the weak part includes a fifth weak part and a sixth weak part in the electrode assembly of a secondary battery according to the present application;

[0035] Figure 14 Structure diagram of a structure in which the second weak part is provided at both ends of the fifth weak part in the electrode assembly of a secondary battery according to the present application;

[0036] Figure 15 Structure diagram of a structure in which the second weak part is provided at the end of the sixth weak part in the electrode assembly of a secondary battery according to the present application;

[0037] Figure 16 Structure diagram of a structure in which the second weak part is provided at both the fifth weak part and the sixth weak part in the electrode assembly of a secondary battery according to the present application;

[0038] Figure 17 Fig. 5 is a structural schematic view of a secondary battery according to another example of the present application;

[0039] Figure 18 Fig. 1 is a schematic view of a battery pack according to an example of the present application;

[0040] Figure 19 Fig. 3 is a schematic view of an electronic device according to an example of the present application.

[0041] Element number explanation:

[0042] 100, secondary battery; 110, housing; 111, end wall; 1111, first end wall; 1112, second end wall; 112, explosion-proof valve; 1121, explosion-proof notch; 113, side wall; 120, electrode assembly; 121, positive electrode tab; 1211, positive current collector; 1212, first coating area; 1213, first non-coating area; 122, separator; 123, negative electrode tab; 1231, negative current collector; 1232, second coating area; 1233, second non-coating area; 124, first tab; 125, second tab; 130, current collecting member; 1301, through hole; 131, body portion; 132, tab connecting portion; 133, housing connecting portion; 140, orthographic projection contour; 150, weak portion; 151, first weak portion; 152, second weak portion; 153, third weak portion; 154, fourth weak portion; 155, fifth weak portion; 156, sixth weak portion; 160, tear portion; 1601, tear opening; 1602, tear unit; 1603, first tear portion; 1604, second tear portion; 170, electrode terminal; 200, battery pack; 210, box body; 211, first box body portion; 212, second box body portion; 300, electronic device; 310, working portion. DETAILED DESCRIPTION

[0043] The present application will be described in detail below with reference to specific embodiments. Other advantages and effects of the present application can be easily understood by those skilled in the art from the content disclosed in the specification. The present application can also be implemented or applied in other different specific embodiments, and each detail in the specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following examples and features in the examples can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present application are for describing specific specific embodiments, and are not intended to limit the protection scope of the present application. The test methods not specified in the following examples are usually performed under conventional conditions or under conditions recommended by the manufacturers.

[0044] When the embodiments give a numerical range, it should be understood that, unless otherwise specified by the utility model, both ends of each numerical range and any one numerical between the two ends can be selected. Unless otherwise defined, all technical and scientific terms used in the utility model are used by the skilled in the art and the description of the utility model, and any method, equipment and material of the prior art similar or equivalent to the method, equipment and material described in the embodiments of the utility model can be used to realize the utility model.

[0045] It should be understood that the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in the specification are only for the convenience of clear description, and are not used to limit the scope of the utility model, and the change or adjustment of the relative relationship is also regarded as the scope of the utility model without substantial change of technical content.

[0046] Please refer to Figures 1 to 19 The utility model provides a kind of secondary battery 100, battery pack 200 and electronic device 300, the secondary battery 100 can improve the tearing effect of current collecting member 130 when explosion-proof valve 112 opens by limiting the projection area size of current collecting member 130 falling into the orthographic projection area of explosion-proof valve 112, and then the pressure relief effect of secondary battery 100 can be improved, and the risk of explosion of secondary battery 100 due to excessive pressure is reduced.

[0047] Please refer to Figure 1 And Figure 2 The secondary battery 100 includes a housing 110, an electrode assembly 120 and a current collecting member 130. The housing 110 has a receiving cavity formed therein for accommodating the electrode assembly 120, electrolyte (not shown) and other components. The housing 110 can be open at one end or both ends. Specifically, the size of the housing 110 can be determined according to the specific size of the electrode assembly 120, such as a diameter of 46 mm, a height of 80 mm, 95 mm, 120 mm, etc. The material of the housing 110 can be various, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the housing 110 from rusting during long-term use, a layer of anti-rust material such as metal nickel can be plated on the surface of the housing 110.

[0048] As Figure 1 And Figure 2As shown, the shell 110 includes a cylindrical side wall 113 and an end wall 111, and the end wall 111 is provided with a pressure relief valve 112. The end wall 111 can be a first end wall 1111 which closes one end of the side wall 113, or a second end wall 1112 which closes the other end of the side wall 113, and the second end wall 1112 is provided with an electrode terminal 170. The first end wall 1111 and one end of the side wall 113 can be sealingly connected by welding or mechanical force, and the second end wall 1112 and the other end of the side wall 113 can be integrally formed by stamping or can be connected by welding. The pressure relief valve 112 can be provided on the first end wall 1111, as shown in Figure 2 , or can be provided on the second end wall 1112, as shown in Figure 3 .

[0049] The pressure relief valve 112 can be opened when the internal pressure of the secondary battery 100 exceeds a threshold value, so as to release the pressure inside the shell 110 and complete the directional pressure relief of the secondary battery 100. The pressure relief valve 112 can be a pressure relief valve sheet installed on the first end wall 1111, or can be a pressure relief score 1121 arranged around. Alternatively, please refer to Figure 2 , in this embodiment, the pressure relief valve 112 is a pressure relief score 1121. The pressure relief score 1121 can be coaxially arranged with the first end wall 1111, or can be arranged non-coaxially. Preferably, in order to facilitate the positioning and processing of the pressure relief score 1121 on the first end wall 1111, in this embodiment, the pressure relief score 1121 is coaxially arranged with the first end wall 1111.

[0050] Please refer to Figure 1 and Figure 4 , the electrode assembly 120 is arranged inside the shell 110, and the electrode assembly 120 is a component in which an electrochemical reaction occurs in the secondary battery 100. The shell 110 can contain one or more electrode assemblies 120. The electrode assembly 120 includes a tab and a separator 122, and the tab and the separator 122 are wound to form a wound structure. Specifically, in this embodiment, the electrode assembly 120 includes a positive electrode tab 121, a separator 122, and a negative electrode tab 123 which are wound axially around the shell 110.

[0051] Please refer to Figure 4 , the positive electrode tab 121 includes a positive electrode current collector 1211 and a positive electrode active material layer coated on the positive electrode current collector 1211, and the positive electrode current collector 1211 has a first coated area 1212 coated with the positive electrode active material layer and a first uncoated area 1213 not coated with the positive electrode active material layer, the first coated area 1212 and the first uncoated area 1213 are arranged axially along the shell 110, and the first uncoated area 1213 extends to the outside of the separator 122 at one end of the height direction of the secondary battery 100 and is bent to the axis of the shell 110 to form a stacked positive electrode tab.

[0052] Please continue to refer toFigure 4 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, and a second coated area 1232 coated with the negative electrode active material layer and a second uncoated area 1233 not coated with the negative electrode active material layer are formed on the negative electrode current collector 1231, the second coated area 1232 and the second uncoated area 1233 are arranged axially along the shell 110, the second uncoated area 1233 extends to the outside of the diaphragm 122 towards the other end of the height direction of the secondary battery 100, and is bent towards the axis of the shell 110 to form a stacked negative electrode tab.

[0053] Please continue to refer to Figure 4 The diaphragm 122 is arranged between the positive electrode sheet 121 and the negative electrode sheet 123 to separate the positive electrode active material layer and the negative electrode active material layer. Taking the lithium ion secondary battery 100 as an example, the material of the positive electrode current collector 1211 can be aluminum, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium, or lithium manganate, etc. The material of the negative electrode current collector 1231 can be copper, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material can be carbon or silicon, etc. The base material of the diaphragm 122 can be polypropylene (PP) or polyethylene (PE), etc. In order to protect and insulate the electrode assembly 120, an insulating film can also be wrapped outside the electrode assembly 120, and the insulating film can be synthesized by PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC), or other high molecular polymer materials.

[0054] Please continue to refer to Figure 1 and Figure 4 In an example of the secondary battery 100 of the utility model, the electrode assembly 120 is sealingly installed in the shell 110. The electrode assembly 120 is provided with a first tab 124 and a second tab 125 at both ends in the height direction of the secondary battery 100 respectively, and the polarities of the first tab 124 and the second tab 125 are opposite, wherein the first tab 124 faces the opening of the shell 110, and the first tab 124 is a negative electrode tab. It should be noted that in other embodiments, the first tab 124 can also be a positive electrode tab, and the second tab 125 is a negative electrode tab.

[0055] The current collecting member 130 is arranged in the shell 110, and the current collecting member 130 is arranged on the side of the electrode assembly 120 facing the end wall 111. It should be noted that when the explosion-proof valve 112 is arranged on the first end wall 1111, the current collecting member 130 is arranged towards the first end wall 1111, such as Figure 2As shown. When the explosion-proof valve 112 is arranged at the second end wall 1112, the current collecting member 130 is arranged towards the second end wall 1112, as shown. Figure 3 As shown. For the convenience of description, in the embodiment, the explosion-proof valve 112 is arranged at the first end wall 1111, and then the current collecting member 130 is arranged towards the first end wall 1111. The current collecting member 130 comprises a body part 131, a plurality of shell connecting parts 133 and a plurality of tab connecting parts 132. The plurality of shell connecting parts 133 are connected to the outer periphery of the body part 131 and are electrically connected with the shell 110. The electrical connection mode can be various, for example, the shell connecting part 133 can be welded with the first end wall 1111, the first end wall 1111 is welded with the side wall 113, and then the electrical connection between the current collecting member 130 and the shell 110 is realized. The tab connecting part 132 can also be directly welded with the side wall 113 to realize the electrical connection between the current collecting member 130 and the shell 110. Alternatively, in the embodiment, the tab connecting part 132 is welded with the side wall 113 to realize the electrical connection between the current collecting member 130 and the shell 110.

[0056] Please refer to Figure 2 and Figure 5 The plurality of tab connecting parts 132 are arranged around the center of the current collecting member 130 and are connected with the body part 131. The plurality of tab connecting parts 132 are all welded with the first tab 124 to realize the electrical connection between the current collecting member 130 and the electrode assembly 120. When the explosion-proof valve 112 is opened, the tab connecting part 132 is folded towards the side away from the electrode assembly 120 to expose the end face of the first tab 124 away from the first tab 124. Along the circumferential direction of the current collecting member 130, the adjacent tab connecting parts 132 are provided with a weak part 150, and the weak part 150 makes the adjacent tab connecting parts 132 easy to be folded when the explosion-proof valve 112 is opened. The weak part 150 can be a thinning area formed by bumping, a thinning area formed by scoring, a hollow structure or any other structure that is easy to fold the adjacent tab connecting parts 132 when the explosion-proof valve 112 is opened. Preferably, please refer to Figure 5 In the embodiment, the weak part 150 is a hollow structure. Since the hollow structure is in the form of a through hole 1301, the forming method is simple, and the processing difficulty of the weak part 150 can be reduced. The weak part 150 can be a straight line segment structure, a curved line segment structure, a combination structure of straight line segment and curved line segment, etc. The weak part 150 can extend along the radial direction of the current collecting member 130, or can extend away from the radial direction of the current collecting member 130. In order to facilitate the positioning and processing of the weak part 150 on the current collecting member 130, preferably, in the embodiment, the weak part 150 is a straight line segment extending along the radial direction of the current collecting member 130, and the weak parts 150 between the adjacent tab connecting parts 132 are arrayed along the center of the current collecting member 130.

[0057] The normal projection area of the explosion-proof valve 112 along the stacking direction of the end wall 111 and the electrode assembly 120 is S, the projection area of the current collecting member 130 falling into the normal projection area of the explosion-proof valve 112 is S1, and 0.4S≤S1<S. In this way, the shielding area of the current collecting member 130 on the pressure relief path of the explosion-proof valve 112 can be limited, and when the explosion-proof valve 112 opens for pressure relief, the current collecting member 130 can be subjected to a large enough airflow impact pressure, thereby facilitating the tearing of the current collecting member 130, improving the tearing effect of the current collecting member 130, ensuring the folding area of the tab connecting portion 132, reducing the shielding of the current collecting member 130 to the pressure relief path of the explosion-proof valve 112 during pressure relief, and thus improving the pressure relief effect of the secondary battery 100 and reducing the risk of explosion of the secondary battery 100 due to excessive pressure. At the same time, since the current collecting member 130 is provided with the weak portion 150 between adjacent tab connecting portions 132, the weak portion 150 can make the adjacent tab connecting portions 132 easy to fold when the explosion-proof valve 112 is opened, which can further improve the tearing effect of the current collecting member 130, thereby further improving the pressure relief speed and effect of the secondary battery 100.

[0058] Please refer to Figure 5 In an example of the secondary battery 100 of the present application, the central region of the current collecting member 130 is provided with a tearing portion 160, one end of the tearing portion 160 is arranged close to the center of the current collecting member 130, the tearing portion 160 is connected between adjacent weak portions 150, and the tearing portion 160 is torn when the explosion-proof valve 112 is opened. The tearing portion 160 can be a plurality of solid portions distributed between adjacent tab connecting portions 132, or it can be an integral solid portion arranged in the central region of the current collecting member 130. Alternatively, in this embodiment, the tearing portion 160 is an integral solid portion arranged in the central region of the current collecting member 130. In this way, the plurality of tab connecting portions 132 in the central region of the current collecting member 130 can be connected to each other through the tearing portion 160, thereby reducing the probability of warping deformation of the central region of the current collecting member 130 and facilitating the installation and positioning of the current collecting member 130 in the housing 110.

[0059] In the embodiment, the tear part 160 is arranged in the center region of the current collecting member 130, and is connected between the adjacent weak parts 150, and is torn when the explosion-proof valve 112 is opened. Therefore, when the explosion-proof valve 112 is opened, the uniformity of the tearing area between the plurality of tab connecting parts 132 can be ensured, and the current collecting member 130 can obtain a better tearing effect. Meanwhile, since the tear part 160 is far away from the tab connecting part 132, the transmission of the extrusion stress generated when the shell 110 is sealed to the tear part 160 can be reduced, and the probability of tearing of the tear part 160 when the explosion-proof valve 112 is not opened can be reduced, thereby improving the stability of the electrical connection between the current collecting member 130 and the electrode assembly 120.

[0060] Please refer to Figure 6 In an example of the secondary battery 100, the center region of the current collecting member 130 is provided with a through hole 1301, which can be a circular hole, a rectangular hole or a polygonal hole. Alternatively, in the embodiment, the through hole 1301 is a circular hole. The tear part 160 is arranged between the through hole 1301 and the weak part 150, and the through hole 1301 is connected to the weak part 150 through the tear part 160. Specifically, the tear part 160 includes a plurality of tear units 1602, which are arranged around the outer periphery of the through hole 1301, each tear unit 1602 corresponds to a weak part 150, and each weak part 150 is connected to the through hole 1301 through a tear unit 1602. By arranging the through hole 1301 in the center of the current collecting member 130, when the explosion-proof valve 112 is opened, the high-pressure gas will first be quickly discharged from the through hole 1301, and then a greater impact force will be generated on the tear unit 1602 at the edge of the through hole 1301, thereby facilitating the rapid tearing of the tear part 160, and improving the folding speed of the tab connecting part 132, and ensuring the pressure relief effect of the secondary battery 100.

[0061] In order to further improve the tearing speed of the tear part 160, in an example of the secondary battery 100, please continue to refer to Figure 6The tearing part 160 comprises tearing openings 1601 which are in communication with the through holes 1301 and are located on the extension line of the weak part 150. The tearing openings 1601 can be in various shapes such as U-shaped openings, rectangular openings or arc-shaped openings. Specifically, the number of the tearing openings 1601 corresponds to the number of the tearing units 1602, that is, one tearing opening 1601 corresponds to one tearing unit 1602. In this way, when the explosion-proof valve 112 is opened, the high-pressure gas passes through the through holes 1301, and the tearing part 160 will first start tearing at the tearing openings 1601, thereby realizing the rapid tearing of the tearing units 1602, improving the tearing speed of the tearing part 160, and further improving the folding speed of the tab connecting part 132 and the pressure relief speed of the secondary battery 100.

[0062] Please refer to Figure 7 In an example of the secondary battery 100 of the utility model, the weak part 150 extends along the radial direction of the current collecting member 130, one end of the weak part 150 is arranged close to the center of the current collecting member 130, the other end of the weak part 150 extends towards the outer periphery of the current collecting member 130, and adjacent weak parts 150 are in communication with each other close to the center of the current collecting member 130. In this embodiment, the adjacent weak parts 150 intersect at the center of the current collecting member 130, thereby realizing the communication between them. In other embodiments, the center of the current collecting member 130 can be provided with other hollow areas, and the weak parts 150 are in communication with the hollow areas, thereby realizing the communication between the adjacent weak parts 150. By making the adjacent weak parts 150 communicate with each other close to the center of the current collecting member 130, the hollow area can be formed in the central region of the current collecting member 130, the adjacent tab connecting parts 132 are completely disconnected in the central region of the current collecting member 130, the weak part 150 divides the adjacent tab connecting parts 132, and the tab connecting part 132 forms a cantilever structure, so that when the explosion-proof valve 112 is opened, the adjacent tab connecting parts 132 can be quickly folded because they are not connected with each other, thereby further improving the pressure relief speed of the secondary battery 100.

[0063] In order to facilitate the communication between the adjacent weak parts 150, optionally, please refer to Figure 8In the secondary battery 100 example of the utility model, the center area of the current collecting component 130 is provided with a through hole 1301, and the end of the weak part 150 close to the center of the current collecting component 130 is communicated with the through hole 1301. By setting the through hole 1301, the connection between adjacent weak parts 150 can be realized through the through hole 1301, which not only facilitates the communication between adjacent weak parts 150, but also, due to the setting of the through hole 1301, when the explosion-proof valve 112 is opened, the high-pressure gas can be quickly discharged from the through hole 1301, and in turn, a greater airflow impact force can be generated on the tab connecting part 132 around the through hole 1301, which can further improve the folding speed of the tab connecting part 132, thereby further improving the pressure relief speed of the secondary battery 100.

[0064] Please refer to Figures 5 to 8 In the secondary battery 100 example of the utility model, the positive projection profile 140 formed by the explosion-proof valve 112 on the current collecting component 130 is a circular profile, the weak part 150 extends along the radial direction of the current collecting component 130, the end of the weak part 150 away from the center of the current collecting component 130 extends to the outside of the positive projection profile 140 and forms an intersection area with the positive projection profile 140, which can be an intersection point or an intersection line, determined by the structure of the weak part 150. When the tab connecting part 132 is bent, a root bending line (as shown by the dashed line in 8) is formed at the end of the weak part 150 away from the center of the current collecting component 130, and under the premise of keeping the extension direction between adjacent weak parts 150 unchanged, the closer the position of the root bending line to the positive projection profile 140, the longer the length of the root bending line, the greater the bending area generated when the tab connecting part 132 is bent, and in turn, the more conducive to the pressure relief of the secondary battery 100. In this embodiment, by extending the end of the weak part 150 away from the center of the current collecting component 130 to the outside of the positive projection profile 140, the line between the two intersection areas on both sides of the tab connecting part 132 is the root bending line when the tab connecting part 132 is folded, and relative to the structure inside the positive projection profile 140 of the root bending line, a longer root bending line can be obtained, thereby increasing the bending area of the tab connecting part 132 and reducing the area shielding of the current collecting component 130 to the opening path of the explosion-proof valve 112 when the explosion-proof valve 112 is opened, further improving the pressure relief effect of the secondary battery 100.

[0065] In order to further increase the area of the tab connecting part 132 folded when the explosion-proof valve 112 is opened and reduce the area shielding of the current collecting component 130 to the pressure relief path of the explosion-proof valve 112, further, on the basis of forming an intersection area between the weak part 150 and the positive projection profile 140, please refer to Figure 8In the secondary battery 100 example of the utility model, set the circumference of the orthographic projection outline 140 for L, along the circumferential direction of the orthographic projection outline 140, multiple root bending lines divide the orthographic projection outline 140 into multiple circular arc segments. The arc length of the shortest circular arc segment between the adjacent intersection regions of the orthographic projection outline 140 is L1, that is, the arc length of the shortest circular arc segment of the orthographic projection outline 140 corresponding to each root bending line is L1, and L1 is less than or equal to 1 / 5 of L.

[0066] Since the arc length of the circular arc segment corresponding to each root bending line is directly proportional to the length of the root bending line, and the length of the root bending line is related to the number of weak parts 150, the more the number of weak parts 150, the smaller the interval angle between adjacent weak parts 150, and therefore the shorter the root bending line, the shorter the arc length corresponding to the root bending line, Figure 8 the area of the shadow area in the formula is also smaller, and the pressure relief effect of the explosion-proof valve 112 is better. In the embodiment, by limiting L1 to be less than or equal to 1 / 5 of L, the number of weak parts 150 can be limited, so that the number of weak parts 150 can meet the size requirement of the area of the shadow area in the formula, to ensure the pressure relief effect of the explosion-proof valve 112, and also avoid setting too many weak parts 150, to reduce the production cost and ensure the stability of the welding connection between the current collecting member 130 and the first tab 124. Figure 8

[0067] In order to further reduce the arc length of the shortest circular arc segment of the orthographic projection outline 140 corresponding to the root bending line, to further reduce the area shielding of the current collecting member 130 to the pressure relief path of the explosion-proof valve 112 when the explosion-proof valve 112 is opened, optionally, please refer to Figure 9 In the secondary battery 100 example of the utility model, the weak part 150 includes a first weak part 151 and a second weak part 152, the first weak part 151 extends along the radial direction of the current collecting member 130, one end of the first weak part 151 is arranged close to the center of the current collecting member 130, and the other end of the first weak part 151 is connected with the second weak part 152. The second weak part 152 extends along the circumferential direction of the orthographic projection outline 140, that is, the second weak part 152 is a circular arc segment structure coaxially arranged with the orthographic projection outline 140. Along the circumferential direction of the second weak part 152, the orthographic projection outline 140 extends through both ends of the extension direction of the second weak part 152. Along the circumferential direction of the orthographic projection outline 140, the second weak part 152 can extend towards one side of the first weak part 151, or extend towards both sides of the first weak part 151. Optionally, in the embodiment, the two ends of the second weak part 152 symmetrically extend towards both sides of the first weak part 151, and this arrangement can facilitate the positioning and processing between the second weak part 152 and the first weak part 151.

[0068] ​In the embodiment, by setting the second weak portion 152 and extending the second weak portion 152 along the circumferential direction of the orthographic projection contour 140, the length of the root bending line between the adjacent weak portions 150 can be reduced under the condition that the interval angle between the adjacent weak portions 150 is unchanged, and then the shortest arc length of the orthographic projection contour 140 corresponding to the root bending line can be reduced, so that the area of the shadow area can be reduced under the condition that the number of the weak portions 150 is small, and the area shielding of the pressure relief path of the explosion-proof valve 112 by the current collecting member 130 when the explosion-proof valve 112 is opened can be reduced, and the pressure relief effect of the secondary battery 100 is ensured. Figure 9

[0069] Please refer to Figure 11 In an example of the secondary battery 100 of the utility model, the weak portion 150 includes a third weak portion 153 and two fourth weak portions 154, the third weak portion 153 extends along the radial direction of the current collecting member 130 and is arranged close to the center of the current collecting member 130. In an embodiment, the center position of the current collecting member 130 can not be provided with the through hole 1301, the center position of the current collecting member 130 is provided with the tearing portion 160, and the third weak portion 153 is connected with the tearing portion 160, as shown in FIG. 4. Figure 11 In another embodiment, the center position of the current collecting member 130 is provided with the through hole 1301, the outer periphery of the through hole 1301 is provided with the tearing portion 160, and the third weak portion 153 is connected with the tearing portion 160, as shown in FIG. 5. Figure 12

[0070] The two fourth weak portions 154 are arranged at one end of the third weak portion 153 away from the center of the current collecting member 130, and the two fourth weak portions 154 are respectively located on both sides of the extension line of the third weak portion 153. Each fourth weak portion 154 extends from one side close to the extension line of the third weak portion 153 to one side away from the extension line of the third weak portion 153 and extends to the outside of the orthographic projection contour 140, and each fourth weak portion 154 intersects with the orthographic projection contour 140 to form an intersection area. The two fourth weak portions 154 can be symmetrically arranged on both sides of the extension line of the third weak portion 153, or can be asymmetrically arranged on both sides of the extension line of the third weak portion 153. Preferably, in the embodiment, in order to facilitate the machining and positioning of the weak portion 150, the two fourth weak portions 154 are symmetrically arranged on both sides of the extension line of the third weak portion 153.

[0071] ​​By setting two fourth weakened portions 154 at one end of the third weakened portion 153 away from the center of the current collecting member 130, each of the weakened portions 150 can form two intersection regions with the orthographic projection contour 140, and the two intersection regions are arranged at intervals along the circumferential direction of the orthographic projection contour 140. In this way, under the premise that the number of the weakened portions 150 is unchanged, the orthographic projection contour 140 can be divided into more circular arc segments by the weakened portions 150, thereby facilitating the shortening of the arc length of each circular arc segment, and accordingly, the shielding of the pressure relief path of the explosion-proof valve 112 by the current collecting member 130 when the explosion-proof valve 112 is opened can be reduced, and the pressure relief effect of the explosion-proof valve 112 can be improved.

[0072] Please refer to Figure 13 In an example of the secondary battery 100 of the utility model, the center of the current collecting member 130 is provided with a tear portion 160, which is torn when the explosion-proof valve 112 is opened. The weakened portion 150 includes a fifth weakened portion 155 and two sixth weakened portions 156. The fifth weakened portion 155 penetrates the tear portion 160 along the radial direction of the current collecting member 130, and divides the tear portion 160 into a first tear portion 1603 and a second tear portion 1604. The two sixth weakened portions 156 each extend along the radial direction of the current collecting member 130, and the two sixth weakened portions 156 are respectively arranged on the two sides of the fifth weakened portion 155. The two sixth weakened portions 156 can be symmetrically arranged on the two sides of the fifth weakened portion 155, or can be asymmetrically arranged on the two sides of the fifth weakened portion 155. Preferably, in this embodiment, the two sixth weakened portions 156 are symmetrically arranged on the two sides of the fifth weakened portion 155, which facilitates the positioning and processing between the sixth weakened portion 156 and the fifth weakened portion 155.

[0073] One end of one of the sixth weakened portions 156 close to the center of the current collecting member 130 is connected with the first tear portion 1603, and one end of the other sixth weakened portion 156 close to the center of the current collecting member 130 is connected with the second tear portion 1604. In this way, when the explosion-proof valve 112 is opened, only the first tear portion 1603 and the second tear portion 1604 need to be torn to achieve the tearing of the plurality of tab connecting portions 132 at the center of the current collecting member 130, and therefore the tearing speed of the current collecting member 130 when the explosion-proof valve 112 is opened can be further improved, and the tearing effect of the current collecting member 130 can be improved, thereby improving the pressure relief effect of the secondary battery 100.

[0074] Further, please refer to Figures 14 to 16 On the basis of the above-mentioned embodiment, in an example of the secondary battery 100 of the utility model, the weakened portion 150 further includes a second weakened portion 152, which is arranged at the two ends of the fifth weakened portion 155, and the second weakened portion 152 is in communication with the fifth weakened portion 155, such as Figure 14The second weak portion 152 can be symmetrically arranged at both ends of the fifth weak portion 155 or asymmetrically arranged at both ends of the fifth weak portion 155. In the embodiment, preferably, two second weak portions 152 are symmetrically arranged at both ends of the fifth weak portion 155. The second weak portion 152 is a circular arc segment extending in the circumferential direction of the orthographic projection contour 140, and the specific extension length of the second weak portion 152 is not limited. In the circumferential direction of the orthographic projection contour 140, the orthographic projection contour 140 penetrates the second weak portion 152.

[0075] In another embodiment, referring to Figure 15 , the second weak portion 152 can also be arranged at one end of the sixth weak portion 156 away from the center of the current collecting member 130. In other embodiments, referring to Figure 16 and Figure 17 , the second weak portion 152 can also be arranged at both ends of the fifth weak portion 155, and one end of the sixth weak portion 156 away from the center of the current collecting member 130 can also be arranged with the second weak portion 152.

[0076] It should be noted that the extension length of the second weak portion 152 is not limited in the embodiment, and as shown in Figure 16 , the extension length of the second weak portion 152 can be short. As shown in Figure 17 , the extension length of the second weak portion 152 can also be long. The longer the extension length of the second weak portion 152, the larger the folding area of the tab connecting portion 132 when the explosion-proof valve 112 is opened, which is more conducive to improving the pressure relief effect of the explosion-proof valve 112. In the actual design and production process, various factors such as the size of the orthographic projection contour 140 and the folding area of the tab connecting portion 132 need to be considered comprehensively.

[0077] By arranging the second weak portion 152, the length of the line segment between the adjacent intersection regions of the weak portion 150 and the orthographic projection contour 140, i.e., the length of the root bending line, can be shortened, so that the arc length of the orthographic projection contour 140 corresponding to the root bending line can be shortened, the shielding of the current collecting member 130 to the pressure relief path of the explosion-proof valve 112 when the explosion-proof valve 112 is opened can be reduced, and the pressure relief effect of the explosion-proof valve 112 can be improved.

[0078] Referring to Figure 18 , in an embodiment of the battery pack 200, the battery pack 200 includes a box body 210 and at least one secondary battery 100; the box body 210 includes a first box body portion 211 and a second box body portion 212, the first box body portion 211 and the second box body portion 212 are mutually covered to form an accommodation space, and a plurality of secondary batteries 100 are accommodated in the accommodation space, and the plurality of secondary batteries 100 can be connected in series and / or parallel. The battery pack 200 can be, for example, a battery module, a battery pack, etc.

[0079] Referring to Figure 19In an example of the electronic device 300, the electronic device 300 includes a working part 310 and a battery pack 200, and the working part 310 is electrically connected with the battery pack 200 to obtain power support. The working part 310 can be a unit component capable of obtaining the power of the battery pack 200 and making corresponding work, such as a fan blade rotating unit, a dust suction working unit of a dust collector, a wheel driving unit in an electric vehicle, and the like. The electronic device 300 can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle can be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile, or a range extended automobile, and the like. The spacecraft includes an airplane, a rocket, a space shuttle, a spacecraft, and the like. The electric toy includes a fixed or mobile electric toy, such as a game machine, an electric automobile toy, an electric ship toy, an electric airplane toy, and the like. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, an electric planer, and the like. The electronic device 300 is not specially limited in the embodiments of the present application. In an example of the electronic device 300, the electronic device 300 is a vehicle, the working part 310 is a vehicle body, and the battery pack 200 is fixedly installed on the vehicle body, thereby providing driving force for the vehicle and realizing the running of the vehicle.

[0080] In the secondary battery, the normal projection area of the explosion-proof valve is S, the projection area of the current collecting member falling into the normal projection area of the explosion-proof valve is S1, and 0.4S≤S1

[0081] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A secondary battery characterized by comprising: The application relates to a battery, which comprises: a shell comprising an end wall provided with an explosion-proof valve; an electrode assembly arranged in the shell, the electrode assembly being provided with a first lug on a side facing the end wall; a current collecting member arranged on a side of the electrode assembly facing the end wall and electrically connected with the shell, the current collecting member comprising a plurality of lug connecting portions, each of the lug connecting portions being welded with the first lug and being folded towards a side away from the electrode assembly when the explosion-proof valve is opened, and a weak portion being arranged between adjacent lug connecting portions in a circumferential direction of the current collecting member, the weak portion allowing the adjacent lug connecting portions to be easily folded when the explosion-proof valve is opened; wherein the explosion-proof valve has a projected area S in a stacking direction of the end wall and the electrode assembly, the current collecting member has a projected area S1 falling within the projected area of the explosion-proof valve, and 0.4S<=S1<S.

2. The secondary battery according to claim 1, characterized by The central region of the current collecting member is provided with a tearing portion, one end of the weak portion is arranged close to the center of the current collecting member, adjacent weak portions are connected through the tearing portion, and the tearing portion is torn when the explosion-proof valve is opened.

3. The secondary battery according to claim 2, characterized by The central region of the current collecting member is provided with a through hole, the tearing portion is arranged between the through hole and the weak portion, and the through hole is connected with the weak portion through the tearing portion.

4. The secondary battery according to claim 3, characterized by The tearing portion comprises a tearing opening, the tearing opening is communicated with the through hole, and the tearing opening is located on an extension line of the weak portion.

5. The secondary battery according to claim 1, characterized by One end of the weak portion is arranged close to the center of the current collecting member, and adjacent weak portions are communicated with each other close to the center of the current collecting member.

6. The secondary battery according to claim 5, characterized by The central region of the current collecting member is provided with a through hole, and the weak portion is communicated with the through hole.

7. The secondary battery according to any one of claims 1 to 6, characterized by The explosion-proof valve forms a circular projected contour on the current collecting member, and one end of the weak portion away from the center of the current collecting member extends to the outside of the projected contour.

8. The secondary battery according to claim 7, characterized by The circumference of the projected contour is L, the arc length of the shortest circular arc between adjacent weak portions is L1, and L1 is less than or equal to 1 / 5 of L.

9. The secondary battery according to any one of claims 1 to 6, characterized by, The explosion-proof valve forms a circular projected contour on the current collecting member; the weak portion comprises a first weak portion and a second weak portion, one end of the first weak portion is arranged close to the center of the current collecting member, and the other end is connected with the second weak portion; the second weak portion extends along the circumferential direction of the projected contour, and the projected contour penetrates through the second weak portion.

10. The secondary battery according to any one of claims 1 to 6, characterized by The explosion-proof valve forms a circular projected contour on the current collecting member; the weak portion comprises a third weak portion and two fourth weak portions, the third weak portion is arranged close to the center of the current collecting member and extends along the radial direction of the current collecting member; the two fourth weak portions are arranged at one end of the third weak portion away from the center of the current collecting member and are located on both sides of the extension line of the third weak portion; each fourth weak portion extends from a side close to the extension line of the third weak portion to a side away from the extension line of the third weak portion and extends to the outside of the projected contour.

11. The secondary battery according to claim 1, characterized by The center of the current collecting member is provided with a tear part which is torn when the explosion-proof valve is opened; the weak part comprises a fifth weak part and two sixth weak parts, the fifth weak part penetrates the tear part along the radial direction of the current collecting member, and the two sixth weak parts are respectively arranged on the two sides of the fifth weak part and connected with the tear part.

12. The secondary battery according to claim 11, characterized by The explosion-proof valve forms a circular profile in the orthographic projection profile on the current collecting member; the weak part further comprises a second weak part, the second weak part is arranged at the two ends of the fifth weak part and / or one end of the sixth weak part away from the center of the current collecting member; the second weak part extends along the circumference of the orthographic projection profile, and the orthographic projection profile penetrates the second weak part.

13. The secondary battery according to claim 1, characterized by The weak part is a hollow structure.

14. A battery pack, characterized by The secondary battery comprises the secondary battery of any one of claims 1 to 13.

15. An electronic device, comprising: The battery pack comprises the battery pack of claim 14.

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