Secondary battery and electronic device

Abstract

Disclosed in the present application are a secondary battery and an electronic device. The secondary battery comprises a packaging bag, an electrode assembly, an electrical connector, a first insulation member and a second insulation member. The electrode assembly is located in the packaging bag, the electrode assembly comprises a main body and a tab assembly, the tab assembly comprises a plurality of tabs, and the electrical connector is located outside the packaging bag and is electrically connected to the tab assembly. The tab assembly comprises a first portion and a second portion, the first portion extending from the main body and being connected to the second portion, and the second portion being bent towards the main body, forming a weld mark with the electrical connector, and comprising a first surface and a second surface. The first insulation member covers the weld mark, the second insulation member is located on one side of the tab assembly in the direction of thickness, and the second insulation member extends from the first surface of the second portion through the first portion to the main body. The thickness of the first insulation member is T1, and the thickness of the second insulation member is T2, wherein T1＞T2, 25μm≤T1≤60μm, and T2≥4μm, satisfying requirements of both safety performance and drop resistance of the secondary battery.

Description

Secondary batteries and electronic devices Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a secondary battery and electronic device. Background Technology

[0002] As the use of rechargeable batteries in mobile devices, electronic products, and electric vehicles continues to increase, in addition to the growing demand for higher energy density, the safety performance of rechargeable batteries is also receiving much attention. Therefore, improving the safety performance of rechargeable batteries remains a problem that the industry needs to solve. Summary of the Invention

[0003] In view of this, it is necessary to provide a secondary battery and electronic device that takes into account both the safety performance and drop resistance of the secondary battery.

[0004] This application provides a secondary battery, including a packaging bag, an electrode assembly, an electrical connector, a first insulating member, and a second insulating member. The electrode assembly is located inside the packaging bag and includes a main body and a tab assembly extending from the main body. The tab assembly includes multiple tabs. One end of the electrical connector is located outside the packaging bag, and the other end is electrically connected to the tab assembly. The tab assembly includes a first portion and a second portion. The first portion extends from the main body and connects to the second portion. The second portion is bent towards the main body relative to the first portion. The second portion is welded to the electrical connector to form a solder mark, and the second portion includes a first surface facing away from the main body and a second surface facing the main body. The first insulating member is disposed on the first surface of the second portion and covers the solder mark. The second insulating member is located on one side of the tab in the thickness direction and extends from the first surface of the second portion through the first portion to the main body. The thickness of the first insulating member is T1, and the thickness of the second insulating member is T2, where T1 > T2, 25 μm ≤ T1 ≤ 60 μm, and T2 ≥ 4 μm. By covering the solder mark with the first insulating component, the risk of short circuit caused by the solder mark puncturing the packaging bag is reduced. The first surface and the main body are connected by the second insulating component, which fixes the tab and the main body. This reduces the positional displacement of the tab and the main body during handling and use, and reduces the impact of the thickness of the second insulating component on the flatness of the secondary battery. It also reduces the problem of overvoltage at the position of the second insulating component during the formation stage of the secondary battery, and improves the problem of purple spots caused by overvoltage at the position of the second insulating component and capacity loss after cycling of the secondary battery.

[0005] In one or more of the above optional embodiments, the thickness of the electrode assembly is T, and 2T2 / T×100%≤4.1%, which is beneficial to reduce the thickness of the second insulating component, reduce the impact of the thickness of the second insulating component on the flatness of the secondary battery, reduce the problem of overvoltage at the position of the second insulating component during the formation stage of the secondary battery, and improve the problem of purple spots caused by overvoltage at the position of the second insulating component and capacity loss after cycling of the secondary battery.

[0006] In one or more of the above optional embodiments, 2T2 / T×100%≤1.8% is more conducive to reducing the thickness of the second insulating component, reducing the impact of the thickness of the second insulating component on the flatness of the secondary battery, reducing the problem of overvoltage at the position of the second insulating component during the formation stage of the secondary battery, and improving the problem of purple spots caused by overvoltage at the position of the second insulating component and capacity loss after cycling of the secondary battery.

[0007] In one or more of the above optional embodiments, 30μm≤T1≤50μm. Thus, the first insulating element can better reduce the risk of short circuits caused by solder punctures in the packaging bag, reduce the space occupied by the first insulating element, and help reduce costs.

[0008] In one or more of the above optional embodiments, the first insulating member and the second insulating member at least partially overlap on the first surface, which helps to reduce the assembly difficulty and facilitates the pasting of the first insulating member and the second insulating member.

[0009] In one or more of the above optional embodiments, the overlapping area of ​​the second insulating element with the first insulating element at least partially overlaps with the solder mark. This overlapping area helps to further reduce the risk of the solder mark puncturing the packaging bag and causing a short circuit.

[0010] In one or more of the above optional embodiments, in the overlapping area of ​​the first insulating member and the second insulating member, the second part, the second insulating member and the first insulating member are stacked in sequence to prevent the edge of the second insulating member from lifting up, which further helps to fix the tab and the main body and reduces the risk of the tab breaking or falling off under force during the transportation and use of the secondary battery.

[0011] In one or more of the above optional embodiments, along the stacking direction of the second insulating member and the first insulating member, the projection of the first insulating member is located within the second insulating member. This better reduces the risk of short circuits caused by solder punctures in the packaging bag, facilitates the fixing of the tabs and the main body, and reduces the risk of the tabs breaking or detaching under stress during handling and use of the secondary battery.

[0012] In one or more of the above optional embodiments, the area of ​​the first insulating member is A1, the overlap area between the first insulating member and the second insulating member is A, and the secondary battery also satisfies: A≥16.7%A1. This allows for better reduction of the tolerance accuracy between the first and second insulating members, reduces assembly difficulty, facilitates the bonding of the first and second insulating members, improves assembly, and reduces the risk of the second insulating member's edge warping, which could lead to breakage or detachment of the electrode tab under stress.

[0013] In one or more of the above optional embodiments, along the width direction of the main body of the electrode assembly, the width of the first insulating member is W1, and the width of the solder mark is W; along the extension direction of the tab, the length of the first insulating member is L1, and the length of the solder mark is L. The secondary battery also satisfies: 1.5W≤W1≤3W, 1.1L≤L1≤6.7L. This is beneficial for the first insulating member to cover the solder mark, reducing the risk of the solder mark puncturing the packaging bag and causing a short circuit, and reducing the space occupied by the first insulating member inside the packaging bag.

[0014] In one or more of the above optional embodiments, 1.8W≤W1≤2.7W and 1.5L≤L1≤5.4L, which is beneficial for the first insulating component to cover the solder mark, reducing the risk of the solder mark puncturing the packaging bag and causing a short circuit, and further reducing the space occupied by the first insulating component inside the packaging bag.

[0015] In one or more of the above optional embodiments, along the extension direction of the second insulating member, the overlap length between the second insulating member and the main body is L5, and the overlap length between the second insulating member and the electrode and the electrical connector is L6, where 3mm≤L5≤8mm and 3mm≤L6≤13mm. This is beneficial for fixing the main body and the electrode, reducing the risk of the electrode moving or falling off during the movement or use of the secondary battery, reducing the space occupied by the second insulating member in the packaging bag, reducing the impact of the excessive length of the second insulating member on the heat-sealing adhesive layer, and also helping to reduce costs.

[0016] In one or more of the above optional embodiments, the secondary battery also includes an electrolyte sealed in a packaging bag. The peel strength between the first insulating component and the solder mark is greater than 0.26 N / mm, which is beneficial for the first insulating component to adhere to the solder mark, so that the first insulating component covers the burrs on the solder mark and reduces the risk of the solder mark puncturing the packaging bag and causing a short circuit.

[0017] In one or more of the above optional embodiments, the secondary battery also includes an electrolyte sealed in a packaging bag, and the peel strength between the second insulating member and the tab is greater than 0.08 N / mm, which is beneficial for fixing the tab and the main body and reducing the risk of the tab moving or falling off during handling and use.

[0018] In one or more of the above optional embodiments, the secondary battery further includes a third insulating member. The third insulating member is located on the side of the tab opposite to the second insulating member, and extends from the electrical connector sequentially through the second surface of the second part and the first part to the main body. The thickness of the third insulating member is T3, and the secondary battery also satisfies: T1 > T3. By connecting the second surface and the main body with the third insulating member, the tab and the main body are further fixed, reducing the positional displacement of the tab and the main body during handling and use. The thickness of the third insulating member is less than the thickness of the first insulating member, reducing the impact of the thickness of the third insulating member on the flatness of the secondary battery, reducing the problem of overvoltage at the position of the third insulating member during the formation stage of the secondary battery, and improving the problem of purple spots caused by overvoltage at the position of the second insulating member and capacity loss after cycling of the secondary battery.

[0019] In one or more of the above optional embodiments, the thickness of the electrode assembly is T, and the secondary battery also satisfies: 2T3 / T×100%≤4.1%, which is beneficial to reduce the thickness of the third insulating component, reduce the impact of the thickness of the third insulating component on the flatness of the secondary battery, reduce the problem of overvoltage at the position of the third insulating component during the formation stage of the secondary battery, and improve the problem of purple spots caused by overvoltage at the position of the second insulating component and capacity loss after cycling of the secondary battery.

[0020] In one or more of the above optional embodiments, the secondary battery also satisfies: 2T3 / T×100%≤1.8%, which further helps to reduce the thickness of the third insulating component, reduce the impact of the thickness of the third insulating component on the flatness of the secondary battery, reduce the problem of overvoltage at the position of the third insulating component during the formation stage of the secondary battery, and improve the problem of purple spots caused by overvoltage at the position of the second insulating component and capacity loss after cycling of the secondary battery.

[0021] In one or more of the above optional embodiments, along the extending direction of the third insulating member, the overlap length between the third insulating member and the main body is L7, and the overlap length between the third insulating member and the electrode tab and the electrical connector is L8, where 3mm≤L7≤8mm and 7mm≤L8≤13mm. This facilitates fixing the main body and the electrode tab, reduces the risk of the electrode tab shifting or falling off during the movement or use of the secondary battery, reduces the space occupied by the third insulating member in the packaging bag, reduces the impact of excessive length of the third insulating member on the heat-sealing adhesive layer, and helps to reduce costs.

[0022] In one or more of the above optional embodiments, the secondary battery also includes an electrolyte sealed in a packaging bag, and the peel strength between the third insulating component and the tab is greater than 0.08 N / mm, which is beneficial for fixing the tab and the main body and reducing the risk of the tab moving or falling off during handling and use.

[0023] In one or more of the above optional embodiments, the first insulating member, the second insulating member, and the third insulating member all include a base layer and an adhesive layer, with the adhesive layer connecting to the base layer. The base layer includes one or more of polyethylene terephthalate, polyimide, polyester film, polyethylene film, nonwoven fabric, and foam. The adhesive layer includes one or more of acrylic systems, rubber systems, styrene-isoprene-styrene, isooctyl acrylate, octyl methacrylate, isooctyl methacrylate, isoprene, styrene, butyl acrylate, polyacrylic acid, polyacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, and polymethyl methacrylate.

[0024] Embodiments of this application provide an electronic device including the secondary battery in any of the above embodiments. Attached Figure Description

[0025] Figure 1 shows a schematic diagram of the structure of a secondary battery in some embodiments of this application.

[0026] Figure 2 shows a partial structural schematic diagram of the secondary battery in some embodiments of this application.

[0027] Figure 3 shows a cross-sectional schematic diagram of the packaging bag in some embodiments of this application.

[0028] Figure 4 shows a partial structural schematic diagram of the secondary battery in some other embodiments of this application.

[0029] Figure 5 shows a partial structural schematic diagram of the secondary battery in some embodiments of this application.

[0030] Figure 6 shows a simplified structural diagram of the secondary battery in Figure 4 of this application, viewed along the second direction.

[0031] Figure 7 shows a schematic diagram of the structure of an electronic device in some embodiments of this application.

[0032] Key component symbols: Secondary battery 100, Solder mark 101, Packaging bag 10, Protective layer 10a, Metal layer 10b, Adhesive layer 10c, Electrode assembly 20, Main body 21, Tab assembly 22, Connecting section 22a, First part 221, Second part 222, First surface 222a, Second surface 222b, Electrical connector 30, First insulator 40, Second insulator 50, First section 51, Second section 52, Third insulator 60, Third section 61, Fourth section 62, Electronic device 200, First direction X, Second direction Y, Third direction Z

[0033] The following specific embodiments will further illustrate this application in conjunction with the above-described accompanying drawings. Detailed Implementation

[0034] The following specific embodiments are exemplary and not limiting, and are intended to provide a basic understanding of this application, and are not intended to identify key or decisive elements of this application or limit the scope of protection. As long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.

[0035] When a component is considered to be "located" on another component, it can be directly on the other component or may also be interspersed with other components. When a component is considered to be "connected" to another component, it can be directly connected to the other component or may also be interspersed with other components.

[0036] It is understandable that the term "perpendicular" is used to describe an ideal state between two components. In actual production or use, two components can exist in a state that is approximately perpendicular or equal to each other. For example, combined with numerical description, perpendicularity can refer to the angle between two straight lines within the range of 90° ± 10°, the dihedral angle between two planes within the range of 90° ± 10°, or the angle between a straight line and a plane within the range of 90° ± 10°. The two components described as "perpendicular" do not have to be absolutely straight lines or planes; they can be approximately straight lines or planes. From a macroscopic perspective, if the overall direction of extension is a straight line or plane, the component can be considered a "straight line" or "plane".

[0037] The term "parallel" is used to describe an ideal state between two components. In actual production or use, two components may exist in a state that is approximately parallel or equal to each other. For example, in numerical terms, parallel can refer to the angle between two straight lines within the range of 0° ± 10°, the dihedral angle between two planes within the range of 0° ± 10°, or the angle between a straight line and a plane within the range of 0° ± 10°. The two components described as "parallel" do not have to be absolutely straight lines or planes; they can be approximately straight lines or planes. From a macroscopic perspective, if the overall direction of extension is straight or plane, the component can be considered a "straight line" or "plane".

[0038] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0039] Referring to Figures 1 and 2, one embodiment of this application provides a secondary battery 100, including a packaging bag 10 and an electrode assembly 20, the electrode assembly 20 being located within the packaging bag 10. The electrode assembly 20 includes a main body 21 and tab assemblies 22 extending from the main body 21. The tab assembly 22 includes a plurality of tabs.

[0040] In some embodiments, the secondary battery 100 includes an electrical connector 30, one end of which is located outside the packaging bag 10, and the other end is electrically connected to the tab assembly 22.

[0041] In some embodiments, the tab assembly 22 includes a connecting segment 22a, which is formed by a plurality of tabs in the tab assembly 22 being brought together and connected.

[0042] In some embodiments, the connecting segment 22a includes a first portion 221 and a second portion 222, the first portion 221 extending from the main body 21 and connecting the first portion 221 to the second portion 222.

[0043] In some embodiments, the second portion 222 is bent toward the body portion 21 relative to the first portion 221. The second portion 222 includes a first surface 222a facing away from the body portion 21 and a second surface 222b facing the body portion 21. The second portion 222 is welded to the electrical connector 30 to form a solder mark 101.

[0044] In some embodiments, the secondary battery 100 includes a first insulating member 40, which is disposed on a first surface 222a and covers the solder mark 101.

[0045] In some embodiments, the secondary battery 100 includes a second insulating member 50 located on one side of the tab assembly 22 in the thickness direction. The second insulating member 50 extends from the first surface 222a through the first portion 221 and to the main body portion 21.

[0046] In some embodiments, the thickness of the first insulating member 40 is T1, the thickness of the second insulating member 50 is T2, and T1 > T2.

[0047] In some embodiments, 25μm≤T1≤60μm is beneficial for the first insulating element 40 to reduce the risk of short circuit caused by the solder mark 101 puncturing the packaging bag 10, reduce the space occupied by the first insulating element 40, and help reduce costs.

[0048] Optionally, T1 can be any one or any combination of two of the following: 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm, 55μm, 56μm, 57μm, 58μm, 59μm, and 60μm.

[0049] In some embodiments, T2≥4μm helps to reduce the occurrence of situations where the second insulating element 50 is too thin, leading to tearing and failure to provide restraint.

[0050] In this application, the thickness of the second insulating member 50 is less than the thickness of the first insulating member 40. By covering the solder mark 101 with the first insulating member 40, the risk of the solder mark 101 puncturing the packaging bag 10 and causing a short circuit is reduced. The second insulating member 50 connects the first surface 222a and the main body 21, fixing the tab assembly 22 and the main body 21. This reduces the positional displacement of the tab assembly 22 and the main body 21 during handling and use, and reduces the impact of the thickness of the second insulating member 50 on the flatness of the secondary battery 100. It also reduces the problem of overvoltage at the position of the second insulating member 50 during the formation stage of the secondary battery 100, and improves the problem of purple spots caused by overvoltage at the position of the second insulating member 50 and the capacity loss of the secondary battery 100 after cycling.

[0051] In some embodiments, 30μm≤T1≤50μm. Thus, the first insulating element 40 can better reduce the risk of short circuit caused by the solder mark 101 puncturing the packaging bag 10, reduce the space occupied by the first insulating element 40, and help reduce costs.

[0052] Referring to Figure 3, in some embodiments, the packaging bag 10 includes a protective layer 10a, a metal layer 10b, and an adhesive layer 10c. The metal layer 10b is located between the protective layer 10a and the adhesive layer 10c. The protective layer 10a is located on the outermost side of the packaging bag 10, and the adhesive layer 10c is located on the innermost side of the packaging bag 10, for sealing the packaging bag 10. By covering the solder stamp 101 with the second insulating member 50, the risk of the solder stamp 101 piercing the adhesive layer 10c and coming into contact with the metal layer 10b, causing a short circuit in the secondary battery 100, is reduced.

[0053] In some embodiments, the packaging bag 10 is a packaging bag sealed with an encapsulation film (such as aluminum-plastic film), that is, the secondary battery 100 is a soft-pack battery.

[0054] In some embodiments, the device includes a first electrode and a second electrode with different polarities, and a separator disposed between the first electrode and the second electrode.

[0055] In some embodiments, the electrode assembly 20 is a wound structure.

[0056] In some embodiments, the electrode assembly 20 is a stacked structure. When the electrode assembly 20 is a stacked structure, this application also improves the problem that the separator membrane lifts due to stress concentration at the edge of the separator membrane during the stacking process caused by the uneven flatness of the secondary battery 100 with the stacked structure.

[0057] In some embodiments, the thickness direction of the electrode assembly 20 is defined as the first direction X. Along the first direction X, the thickness of the electrode assembly 20 is T, and 2T² / T×100%≤4.1%. This is beneficial to reduce the thickness of the second insulating member 50, reduce the impact of the thickness of the second insulating member 50 on the flatness of the secondary battery 100, reduce the problem of overvoltage at the position of the second insulating member 50 in the formation stage of the secondary battery 100, and improve the problem of purple spots caused by overvoltage at the position of the second insulating member 50 and capacity loss after cycling of the secondary battery 100.

[0058] In some embodiments, 2T2 / T×100%≤1.8% is more conducive to reducing the thickness of the second insulating member 50, reducing the impact of the thickness of the second insulating member 50 on the flatness of the secondary battery 100, reducing the problem of overvoltage at the position of the second insulating member 50 in the formation stage of the secondary battery 100, and improving the problem of purple spots caused by overvoltage at the position of the second insulating member 50 and capacity loss after cycling of the secondary battery 100.

[0059] Referring to Figure 2, in some embodiments, the first insulating member 40 and the second insulating member 50 at least partially overlap on the first surface 222a, which helps to reduce assembly difficulty and facilitates the bonding of the first insulating member 40 and the second insulating member 50.

[0060] In some embodiments, along the stacking direction of the second insulating member 50 and the first insulating member 40, the second insulating member 50 is located on the side of the first insulating member 40 facing the tab assembly 22, which helps to reduce the edge warping of the second insulating member 50 and reduce the risk of the tab assembly 22 breaking or falling off under stress during the handling and use of the secondary battery 100.

[0061] In some embodiments, the area of ​​the first insulating member 40 is A1, and the overlap area between the first insulating member 40 and the second insulating member 50 is A, where A ≥ 16.7% A1. This allows for better reduction of the tolerance accuracy between the first insulating member 40 and the second insulating member 50, reduces assembly difficulty, facilitates the bonding of the first insulating member 40 and the second insulating member 50, improves assembly, and reduces the risk of the second insulating member 50 edge lifting, which could lead to breakage or detachment of the tab assembly 22 under stress.

[0062] Referring to Figure 4, in some embodiments, the overlapping area of ​​the second insulating member 50 and the first insulating member 40 at least partially overlaps with the solder mark 101. The overlapping area helps to further reduce the risk of the solder mark 101 puncturing the packaging bag 10 and causing a short circuit.

[0063] In some embodiments, in the overlapping area of ​​the second insulating member 50 and the first insulating member 40, the second part 222, the second insulating member 50 and the first insulating member 40 are stacked in sequence to prevent the edge of the second insulating member 50 from lifting up, which further helps to fix the tab assembly 22 and the main body 21, and reduces the risk of the tab 33 breaking or falling off under force during the transportation and use of the secondary battery 100.

[0064] Referring to Figure 5, in some embodiments, along the stacking direction of the second insulating member 50 and the first insulating member 40, the projection of the first insulating member 40 is located within the second insulating member 50. This better reduces the risk of a short circuit caused by the solder mark 101 puncturing the packaging bag 10 and facilitates the fixation of the tab assembly 22 and the main body 21, reducing the risk of the tab assembly 22 breaking or falling off under stress during handling and use of the secondary battery 100.

[0065] Please refer to Figure 6. Define the length direction of the second part 222 as the second direction Y, and define the width direction of the main body 21 as the third direction Z. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other.

[0066] In some embodiments, along the third direction Z, the width of the first insulating member 40 is W1, and the width of the solder mark 101 is W, where 1.5W ≤ W1 ≤ 3W. This facilitates the first insulating member 40 covering the solder mark 101, reducing the risk of the solder mark 101 puncturing the packaging bag 10 and causing a short circuit, and also reduces the space occupied by the first insulating member 40 within the packaging bag 10. The width of the solder mark 101 refers to the maximum distance between the two outermost solder marks 101 along the third direction Z.

[0067] Optionally, W1 can be a range of any one or any two of the following: 1.5W, 1.6W, 1.7W, 1.8W, 1.9W, 2.0W, 2.1W, 2.2W, 2.3W, 2.4W, 2.5W, 2.6W, 2.7W, 2.8W, 2.9W, and 3.0W.

[0068] In some embodiments, 1.8W ≤ W1 ≤ 2.7W. This is beneficial for the first insulating member 40 to cover the solder mark 101, reducing the risk of the solder mark 101 puncturing the packaging bag 10 and causing a short circuit, and further reducing the space occupied by the first insulating member 40 within the packaging bag 10.

[0069] In some embodiments, along the extending direction of the tab assembly 22, the length of the first insulating member 40 is L1, and the length of the solder mark 101 is L, where 1.1L ≤ L1 ≤ 6.7L. This facilitates the first insulating member 40 covering the solder mark 101, reducing the risk of the solder mark 101 puncturing the packaging bag 10 and causing a short circuit, and also reduces the space occupied by the first insulating member 40 within the packaging bag 10. The extending direction of the tab assembly 22 is approximately parallel to the first direction X, and the length of the solder mark 101 refers to the maximum distance between the two outermost solder marks 101 in the first direction X.

[0070] Optionally, L1 can be 1.5L, 1.6L, 1.7L, 1.8L, 1.9L, 2.0L, 2.1L, 2.2L, 2.3L, 2.4L, 2.5L, 2.6L, 2.7L, 2.8L, 2.9L, 3.0L, 3.1L, 3.2L, 3.3L, 3.4L, 3.5L, 3.6L, 3.7L, 3.8L, 3.9L, 4.0L, 4.1L, or 4... The range consisting of any one or any two of the following: 0.2L, 4.3L, 4.4L, 4.5L, 4.6L, ​​4.7L, 4.8L, 4.9L, 5.0L, 5.1L, 5.2L, 5.3L, 5.4L, 5.5L, 5.6L, 5.7L, 5.8L, 5.9L, 6.0L, 6.1L, 6.2L, 6.3L, 6.4L, 6.5L, 6.6L, and 6.7L.

[0071] In some embodiments, 1.5L≤L1≤5.4L. This is beneficial for the first insulating member 40 to cover the solder mark 101, reducing the risk of the solder mark 101 puncturing the packaging bag 10 and causing a short circuit, and further reducing the space occupied by the first insulating member 40 within the packaging bag 10.

[0072] Referring to Figure 2, in some embodiments, along the extending direction of the second insulating member 50, the overlap length between the second insulating member 50 and the main body 21 is L5, where 3mm ≤ L5 ≤ 8mm. The overlap length between the second insulating member 50 and the tab assembly 22 and the electrical connector 30 is L6, where 3mm ≤ L5 ≤ 8mm and 3mm ≤ L6 ≤ 13mm. This facilitates the fixation of the main body 21 and the tab assembly 22, reduces the risk of the tab assembly 22 breaking or falling off under stress during the movement or use of the secondary battery 100, reduces the space occupied by the second insulating member 50 within the packaging bag 10, reduces the impact of the excessive length of the second insulating member 50 on the heat-sealing adhesive layer 10c, and helps to reduce costs.

[0073] The overlap length between the second insulating member 50 and the main body 21 refers to the length of the second insulating member 50 bonded to the main body 21, and the overlap length between the second insulating member 50 and the tab assembly 22 and the electrical connector 30 refers to the length of the second insulating member 50 bonded to the tab assembly 22 and the electrical connector 30.

[0074] Optionally, L5 can be any one or any combination of 3mm, 4mm, 5mm, 6mm, 7mm, and 8mm.

[0075] Optionally, L6 can be any one or any combination of 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, and 13mm. In some embodiments, the length of the second insulating member 50 is the sum of the lengths of L5 and L6.

[0076] In some embodiments, the second insulating member 50 includes a first segment 51, which is bonded to the main body 21. The length of the first segment 51 is L5.

[0077] In some embodiments, the second insulating member 50 includes a second segment 52 connecting the first segment 51, the second segment 52 being bonded to the tab assembly 22 and the electrical connector 30. The length of the second segment 52 is L6.

[0078] In some embodiments, the secondary battery 100 includes an electrolyte sealed in a packaging bag 10, and the electrode assembly 20 and the first insulating member 40 are immersed in the electrolyte.

[0079] Please refer to Figures 2 and 4. In some embodiments, when the first insulating member 40 is not in contact with the electrolyte, the peel strength between the first insulating member 40 and the solder mark 101 is greater than 0.3 N / mm, which is beneficial for the first insulating member 40 to adhere to the solder mark 101, so that the first insulating member 40 covers the burrs on the solder mark 101 and reduces the risk of the solder mark 101 puncturing the packaging bag 10 and causing a short circuit.

[0080] In some embodiments, after immersion in the electrolyte, the peel strength between the first insulating element 40 and the solder mark 101 is greater than 0.26 N / mm, which further facilitates the adhesion of the first insulating element 40 to the solder mark 101, so that the first insulating element 40 covers the burrs on the solder mark 101, reducing the risk of the solder mark 101 puncturing the packaging bag 10 and causing a short circuit.

[0081] Please refer to Figure 6. In some embodiments, when the first insulating member 40 and the second insulating member 50 are not in contact with the electrolyte, the peel strength between the first insulating member 40 and the second insulating member 50 is greater than 0.3 N / mm.

[0082] In some embodiments, after immersion in electrolyte at 85°C for 4 hours, the peel strength between the first insulating member 40 and the second insulating member 50 is greater than 0.26 N / mm.

[0083] In some embodiments, the second insulating element 50 is immersed in the electrolyte.

[0084] In some embodiments, when the second insulating member 50 is not in contact with the electrolyte, the peel strength between the second insulating member 50 and the tab assembly 22 is greater than 0.1 N / mm, which is beneficial for fixing the tab assembly 22 and the main body 21 and reducing the displacement of the tab assembly 22 and the main body 21 during handling and use.

[0085] In some embodiments, after immersion in electrolyte, the peel strength between the second insulating member 50 and the tab assembly 22 is greater than 0.08 N / mm, which further helps to fix the tab assembly 22 and the main body 21, and reduces the displacement of the tab assembly 22 and the main body 21 during handling and use.

[0086] Please refer to Figures 2, 4, and 6. The secondary battery 100 includes a third insulating member 60, which is located on the side of the tab assembly 22 opposite to the second insulating member 50. The third insulating member 60 extends from the electrical connector 30, sequentially passing through the second surface 222b of the second portion 222 and the first portion 221, to the main body 21. The thickness of the third insulating member 60 is T3, where T1 > T3. The third insulating member 60 connects the second surface 222b and the main body 21, further fixing the tab assembly 22 and the main body 21, reducing the possibility of positional shifts during handling and use. The thickness of the third insulating member 60 is less than that of the first insulating member 40, reducing the impact of the thickness of the third insulating member 60 on the flatness of the secondary battery 100, reducing the problem of overvoltage at the location of the third insulating member 60 during the formation stage of the secondary battery 100, and improving the problem of purple spots caused by overvoltage at the location of the third insulating member 60 and capacity loss after cycling of the secondary battery 100.

[0087] In some embodiments, T3≥4μm helps to reduce the occurrence of situations where the third insulating element 60 is too thin, leading to tearing and failure to provide restraint.

[0088] In some embodiments, along the first direction X, the thickness of the electrode assembly 20 is T, and 2T³ / T×100%≤4.1%, which is beneficial to reduce the thickness of the third insulating member 60, reduce the impact of the thickness of the third insulating member 60 on the flatness of the secondary battery 100, reduce the problem of overvoltage at the position of the third insulating member 60 in the formation stage of the secondary battery 100, and improve the problem of purple spots caused by overvoltage at the position of the third insulating member 60 and capacity loss after cycling of the secondary battery 100.

[0089] In some embodiments, 2T3 / T×100%≤1.8% is further beneficial to reduce the thickness of the third insulating member 60, reduce the impact of the thickness of the third insulating member 60 on the flatness of the secondary battery 100, reduce the problem of overvoltage at the position of the third insulating member 60 in the formation stage of the secondary battery 100, and improve the problem of purple spots caused by overvoltage at the position of the third insulating member 60 and capacity loss after cycling of the secondary battery 100.

[0090] Please refer to Figure 2. Along the extension direction of the third insulating member 60, the overlap length between the third insulating member 60 and the main body 21 is L7, and the overlap length between the third insulating member 60 and the tab assembly 22 and the electrical connector 30 is L8. 3mm≤L7≤8mm and 3mm≤L8≤13mm, which is beneficial for fixing the main body 21 and the tab assembly 22, reducing the risk of the tab assembly 22 breaking or falling off under force during the movement or use of the secondary battery 100, reducing the space occupied by the third insulating member 60 in the packaging bag 10, reducing the impact of the excessive length of the third insulating member 60 on the heat-sealing adhesive layer 10c, and also helping to reduce costs.

[0091] The overlap length between the third insulating member 60 and the main body 21 refers to the length of the bonding between the third insulating member 60 and the main body 21, and the overlap length between the third insulating member 60 and the tab assembly 22 and the electrical connector 30 refers to the length of the bonding between the third insulating member 60 and the tab assembly 22 and the electrical connector 30.

[0092] Optionally, L7 can be any one or any combination of 3mm, 4mm, 5mm, 6mm, 7mm, and 8mm.

[0093] Optionally, L8 can be any one or any combination of 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, and 13mm.

[0094] In some embodiments, the length of the third insulating member 60 is the sum of the lengths of L7 and L8.

[0095] In some embodiments, the third insulating member 60 includes a third segment 61, which is bonded to the main body 21. The length of the third segment 61 is L7.

[0096] In some embodiments, the third insulating member 60 includes a fourth segment 62 connecting the third segment 61, the fourth segment 62 being bonded to the tab assembly 22 and the electrical connector 30. The length of the fourth segment 62 is L8.

[0097] In some embodiments, the third insulating element 60 is immersed in the electrolyte.

[0098] In some embodiments, when the third insulating member 60 is not in contact with the electrolyte, the peel strength between the third insulating member 60 and the tab assembly 22 is greater than 0.1 N / mm, which is beneficial for fixing the tab assembly 22 and the main body 21 and reducing the displacement of the tab assembly 22 and the main body 21 during handling and use.

[0099] In some embodiments, after immersion in the electrolyte, the peel strength between the third insulating member 60 and the tab assembly 22 is greater than 0.08 N / mm, which further helps to fix the tab assembly 22 and the main body 21, and reduces the displacement of the tab assembly 22 and the main body 21 during handling and use.

[0100] In some embodiments, the first insulating member 40 includes a first base layer and a first adhesive layer connecting the first base layer.

[0101] In some embodiments, the material of the first base layer includes one or a combination of several of polyethylene terephthalate, polyimide, polyester film, polyethylene film, nonwoven fabric, and foam.

[0102] In some embodiments, the material of the first adhesive layer includes one or a combination of several of the following: rubber system, styrene-isoprene-styrene, polypropylene, isoprene or styrene, polyacrylic acid, polyacrylate, polyacrylonitrile, and polyvinylpyrrolidone.

[0103] In some embodiments, the second insulating member 50 includes a second base layer and a second adhesive layer connecting the second base layer.

[0104] In some embodiments, the material of the second base layer includes one or a combination of several of polyethylene terephthalate, polyimide, polyester film, polyethylene film, nonwoven fabric, and foam.

[0105] In some embodiments, the material of the second adhesive layer includes one or a combination of several of the following: acrylic system, rubber system, styrene-isoprene-styrene, isooctyl acrylate, octyl methacrylate, isooctyl methacrylate, isoprene, styrene, butyl acrylate, polyacrylic acid, polyacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, and polymethyl methacrylate.

[0106] In some embodiments, the third insulating member 60 includes a third base layer and a third adhesive layer connecting the third base layer.

[0107] In some embodiments, the material of the third base layer includes one or a combination of several of polyethylene terephthalate, polyimide, polyester film, polyethylene film, nonwoven fabric, and foam.

[0108] In some embodiments, the material of the third adhesive layer includes one or a combination of several of the following: acrylic system, rubber system, styrene-isoprene-styrene, isooctyl acrylate, octyl methacrylate, isooctyl methacrylate, isoprene, styrene, butyl acrylate, polyacrylic acid, polyacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, and polymethyl methacrylate.

[0109] In some embodiments, the peel strength test is conducted using a high-speed rail tensile testing machine according to GB / T2792-2014 "Test Method for Peel Strength of Adhesive Tapes". The test procedure is as follows: The secondary battery is discharged to 0V, then the secondary battery is disassembled, and the first insulating part 40, the tab assembly 22, and the solder mark 101 are removed as a whole. The electrolyte on the surface is wiped off with lint-free paper. Then, it is cut into strips of 5mm × 10mm. Along the length of the sample, the surface of the electrical connector 30 facing away from the first insulating part 40 is adhered to the steel plate with double-sided adhesive (Nitto 5000NS), wherein the adhesion length is not less than 3mm. The steel plate is fixed in the corresponding position of the high-speed rail tensile testing machine. The sample is pulled up and the first insulating part 40 is placed in the clamp and clamped. The angle between the first insulating part 40 and the steel plate is 180° in space. The clamp pulls the sample at a speed of 50 mm / min ± 0.2 mm / s. The average tensile force in the stable area is finally measured and recorded as the peel strength of the first insulating part 40 and the weld mark 101, in N / mm.

[0110] Understandably, when testing the peel strength between the second insulating component 50 and the tab assembly 22, the second insulating component 50 is placed in the clamp and clamped, and the test is performed according to the above test method.

[0111] Understandably, when testing the peel strength between the third insulating component 60 and the tab assembly 22, the third insulating component 60 and the tab assembly 22 are removed as a whole, the third insulating component 60 is placed in the clamp and clamped, and the test is performed according to the above test method.

[0112] The present application will be further described below through specific embodiments.

[0113] 1. Loop testing:

[0114] Cycle capacity retention: The lithium-ion battery was placed in a 25°C environment and allowed to stand for 30 minutes. Then, it was charged and discharged according to the following steps: charged at a constant current of 1.5C to 4.25V, then charged at a constant current of 1.2C to 4.5V, then charged at a constant current of 0.8C to 4.53V, then charged at a constant voltage to 0.14C, allowed to stand for 5 minutes, and then discharged at a constant current of 1C to 3V, allowed to stand for 5 minutes. This constitutes one cycle. The initial discharge capacity C0 of the lithium-ion battery was recorded. This cycle was repeated 500 times, and the discharge capacity C1 after 500 cycles was measured. During the cycle test, the lithium-ion battery was observed for any smoke, fire, or explosion. Capacity retention = C1 / C0 × 100%.

[0115] Purple Spot / Lithium Plaque Area Test: After 500 cycles, the lithium-ion battery was disassembled, and the purple spot and lithium plaque status near the adhesive paper of the negative electrode sheet were observed. The non-lithium plaque area on the negative electrode sheet surface was golden yellow, the purple spot area was dark purple, and the lithium plaque area was grayish-white. The percentage of purple spot / lithium plaque area was calculated based on the total area of ​​the single-sided negative electrode material layer. The criteria for judging the purple spot / lithium plaque status on the negative electrode sheet surface are as follows: Purple spot / lithium plaque area less than or equal to 1% indicates no purple spot or no lithium plaque; purple spot / lithium plaque area less than or equal to 3% indicates slight purple spot / lithium plaque; purple spot / lithium plaque area between 3% and 5% indicates moderate purple spot / lithium plaque; and purple spot / lithium plaque area greater than 5% indicates severe purple spot / lithium plaque.

[0116] 2. Drop Test Method: The lithium-ion battery was placed in a 25℃ environment and left to stand for 30 minutes. Then, it was charged as follows: constant current charging at 0.5C to 4.53V, then constant voltage charging to 0.05C. After standing for 60 minutes, the voltage of the lithium-ion battery before the drop test was measured. The lithium-ion battery was placed in a fixture and dropped freely from a height of 1.5m above the ground using a drop device in the following order: head-tail-right corner of head-right corner of tail-left corner of head-left corner of tail (angle: 45±15°), repeated 6 times. After the drop test, the battery was left to stand at room temperature for 24 hours. The voltage of the lithium-ion battery was measured and recorded. The appearance of the lithium-ion battery was checked and photographed before and after the test. The drop test pass criterion: voltage drop <30mV. The lithium-ion battery was disassembled to observe whether the tabs were broken or torn. If the tabs were not broken or torn, the test was considered passed; otherwise, the test was considered a failure. (20 lithium-ion batteries were tested, and the number of lithium-ion batteries that failed the test was X, with a failure rate of X / 20.)

[0117] In some embodiments, a secondary battery 100, with an initial thickness of 2.43 mm, a length of 110 mm, and a width of 47.6 mm at 50% SOC, is assembled as follows:

[0118] (1) Preparation of negative electrode sheet: The negative electrode active materials artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) are mixed in a weight ratio of 96:1.5:2.5, and deionized water is added as a solvent to prepare a slurry with a weight percentage of 50 wt%, which is then stirred evenly. Foaming adhesive is first applied to a portion of the surface of a 6 μm thick copper foil for the negative electrode current collector. The slurry is then evenly coated onto one surface of the copper foil. Heating is used to remove the foaming adhesive, exposing a portion of the copper foil surface. The foil is then dried at 110 °C to obtain a negative electrode sheet with a single-sided coating of negative electrode active material. When preparing a double-sided coated negative electrode sheet, the above steps are repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a double-sided coating of negative electrode active material. The coated electrode sheet is then cold-pressed to a thickness of 105 μm, and negative electrode tabs are die-cut from the empty foil area at the edge of the negative electrode sheet to form a negative electrode tab assembly.

[0119] (2) Preparation of the positive electrode sheet: Lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97.5:1.0:1.5. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%, and the mixture was stirred evenly. The slurry was uniformly coated on one surface of an aluminum foil and then dried at 90°C to obtain a positive electrode sheet with a single-sided coating of the positive active material. When preparing a double-sided coated positive electrode sheet, the above coating steps were repeated on the other surface of the aluminum foil. The coated electrode sheet was then cold-pressed to a thickness of 95 μm, and positive electrode tabs were die-cut from the empty foil area at the edge of the positive electrode sheet to form a positive electrode tab assembly.

[0120] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are first mixed in a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent. Then, lithium salt lithium hexafluorophosphate (LiPF6) is added to the basic organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0121] (4) Preparation of the isolation membrane: A 7-micron thick porous polyethylene polymer film was used as the isolation membrane.

[0122] (5) Electrode assembly 20 preparation: The positive electrode sheet, the separator and the negative electrode sheet are stacked and arranged, multiple electrode tabs are gathered to form an electrode tab assembly and welded to the electrical connector, and the second insulating part 50, the first insulating part 40 and the third insulating part 60 are attached.

[0123] (6) Assembly of electrode assembly 20: Place the punched aluminum-plastic film in the assembly fixture with the punched surface facing up, place the electrode assembly in the punch, and apply external force to press it tight. Then cover the electrode assembly with another punched aluminum-plastic film with the punched surface facing down, and heat seal the two aluminum-plastic films around their perimeter by hot pressing to obtain the assembled electrode assembly.

[0124] (7) Electrolyte injection and encapsulation: Electrolyte is injected into the assembled electrode assembly, and after vacuum encapsulation, standing, hot pressing formation, shaping and other processes, a secondary battery is obtained.

[0125] It should be noted that, except for the parameters in the table, the parameters in Comparative Examples 1-1 to 1-12 are the same as those in Example 1-1.

[0126] Table 1 (Except for the parameters mentioned in Table 1, all other parameters in Examples 1-2 to 1-15 are the same as those in Example 1-1.)

[0127] As can be seen from Examples 1-1 to 1-15 in Table 1, when T1 > T2, T2 ≥ 4μm, and 25μm ≤ T1 ≤ 60μm, it is beneficial to reduce the risk of the solder mark 101 puncturing the packaging bag 10, reduce the risk of the tab assembly 22 breaking or falling off under stress during handling and use, improve the problems of purple spots and capacity loss after cycling, and improve the drop performance of the second battery 100.

[0128] From Examples 1-8 to 1-15 in Table 1, it can be seen that as the 2T2 / T value decreases, the thickness difference of the secondary battery 100 decreases, and the area of ​​purple spots / lithium plating decreases. When the 2T2 / T value is less than 4.1%, slight purple spots / lithium plating appear at the location of the second insulating component 50; when the 2T2 / T value is less than 1.8%, no purple spots / lithium plating appear at the location of the second insulating component 50.

[0129] Table 2 (Except for the parameters mentioned in Table 2, all other parameters in Examples 2-1 to 2-14 are the same as those in Example 1-1.)

[0130] From Examples 1-1, 2-1 to Examples 2-8 in Table 2, it can be seen that when L1 > 6.7L, there is no significant improvement in improving the capacity loss after cycling. When 1.1L ≤ L1 ≤ 6.7L, it is beneficial for the first insulating element 40 to cover the solder mark 101, reducing the risk of the solder mark 101 puncturing the packaging bag 10 and causing a short circuit, thus improving the capacity loss problem after cycling and saving costs.

[0131] From Examples 1-1, 2-3 to 2-6 in Table 2, it can be seen that when 1.5L≤L1≤5.4L, the problem of capacity loss after cycling is better improved.

[0132] From Examples 2-9 to 2-14 in Table 2, it can be seen that when W1 > 3W, there is no significant improvement in improving the capacity loss after cycling. When 1.5W ≤ W1 ≤ 3W, it is beneficial for the first insulating element 40 to cover the solder mark 101, reducing the risk of the solder mark 101 puncturing the packaging bag 10 and causing a short circuit, thus improving the capacity loss problem after cycling, and also helping to save costs.

[0133] From Examples 2-10 to 2-12 in Table 2, it can be seen that when 1.8W≤W1≤2.7W, there is a significant improvement effect on the capacity loss problem after cycling.

[0134] Table 3 (Except for the parameters mentioned in Table 3, all other parameters in Examples 3-1 to 3-14 are the same as those in Example 1-1.)

[0135] From Examples 1-1, 3-1 to 3-3, 3-5 to 3-11, and 3-13 in Table 3, it can be seen that when 3mm≤L5≤8mm and 3mm≤L6≤13mm, it is beneficial to fix the main body 21 and the tab assembly 22, reduce the risk of the tab assembly 22 breaking or falling off under force during the movement or use of the secondary battery 100, and improve the drop performance of the secondary battery 100.

[0136] From Examples 3-4, 3-12, and 3-14 in Table 3, it can be seen that the portion of L5 greater than 8mm tends to occupy space, resulting in energy density loss and cost loss. The portion of L6 greater than 13mm tends to occupy space, resulting in cost loss, and also occupies the space at the head of the packaging bag 10, which can easily affect the sealing of the packaging bag 10.

[0137] Please refer to Figure 7. This application also provides an electronic device 200 employing the above-described secondary battery 100.

[0138] In one embodiment, the electronic device 200 of this application may be, but is not limited to, a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool.

[0139] Those skilled in the art should recognize that the above embodiments are merely illustrative of this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the spirit and essence of this application fall within the scope of this application's disclosure.

Claims

1. A secondary battery, comprising a packaging bag, an electrode assembly, and an electrical connector, wherein the electrode assembly is located inside the packaging bag, the electrode assembly includes a main body and a tab assembly extending from the main body, the tab assembly includes a plurality of tabs, one end of the electrical connector is located outside the packaging bag, and the other end is electrically connected to the tab assembly, wherein... The electrode assembly includes a first part and a second part, the first part extending from the main body and connecting to the second part, the second part being bent toward the main body relative to the first part, the second part being welded to the electrical connector to form a solder mark, and the second part including a first surface facing away from the main body and a second surface facing the main body; The secondary battery further includes a first insulating member and a second insulating member. The first insulating member is disposed on the first surface of the second portion and covers the solder mark. The second insulating member is located on one side of the thickness direction of the tab and extends from the first surface of the second portion through the first portion to the main body. The thickness of the first insulating member is T1, and the thickness of the second insulating member is T2, where T1 > T2, 25μm ≤ T1 ≤ 60μm, and T2 ≥ 4μm.

2. The secondary battery as described in claim 1, wherein, The thickness of the electrode assembly is T, and 2T² / T×100% ≤ 4.1%.

3. The secondary battery as described in claim 2, wherein, 2T2 / T×100%≤1.8%.

4. The secondary battery as described in claim 1 or 2, wherein, 30μm≤T1≤50μm.

5. The secondary battery according to any one of claims 1 to 4, wherein, The first insulating element and the second insulating element at least partially overlap on the first surface.

6. The secondary battery as described in claim 5, wherein, The overlapping area of ​​the second insulating element with the first insulating element at least partially overlaps with the solder mark.

7. The secondary battery as described in claim 5, wherein, In the overlapping area of ​​the first insulating element and the second insulating element, the second part, the second insulating element and the first insulating element are stacked in sequence.

8. The secondary battery as described in claim 7, wherein, Along the direction in which the second insulating element and the first insulating element are stacked, the projection of the first insulating element is located within the second insulating element.

9. The secondary battery as described in claim 7, wherein, The area of ​​the first insulating element is A1, and the overlap area between the first insulating element and the second insulating element is A, where A ≥ 16.7%A1.

10. The secondary battery according to any one of claims 1 to 9, wherein, Along the width direction of the main body of the electrode assembly, the width of the first insulating member is W1, and the width of the solder mark is W; along the extension direction of the tab, the length of the first insulating member is L1, and the length of the solder mark is L, 1.5W≤W1≤3W, 1.1L≤L1≤6.7L.

11. The secondary battery as claimed in claim 10, wherein, 1.8W≤W1≤2.7W, 1.5L≤L1≤5.4L.

12. The secondary battery according to any one of claims 1 to 11, wherein, Along the extending direction of the second insulating member, the overlap length between the second insulating member and the main body is L5, and the overlap length between the second insulating member and the electrode and the electrical connector is L6, where 3mm≤L5≤8mm and 3mm≤L6≤13mm.

13. The secondary battery according to any one of claims 1 to 12, wherein, The secondary battery also includes an electrolyte sealed in the packaging bag, and the peel strength between the first insulating component and the solder mark is greater than 0.26 N / mm.

14. The secondary battery according to any one of claims 1 to 13, wherein, The secondary battery also includes an electrolyte sealed in the packaging bag, and the peel strength between the second insulating member and the tab is greater than 0.08 N / mm.

15. The secondary battery according to any one of claims 1 to 14, wherein, The secondary battery also includes a third insulating member, which is located on the side of the electrode tab opposite to the second insulating member. The third insulating member extends from the electrical connector, sequentially through the second surface of the second part and the first part to the main body. The thickness of the third insulating member is T3. The secondary battery also satisfies: T1 > T3.

16. The secondary battery as claimed in claim 15, wherein, The thickness of the electrode assembly is T2T3 / T×100%≤4.1%.

17. The secondary battery as claimed in claim 16, wherein, 2T3 / T×100%≤1.8%.

18. The secondary battery as claimed in claim 15, wherein, Along the extending direction of the third insulating member, the overlap length between the third insulating member and the main body is L7, and the overlap length between the third insulating member and the electrode and the electrical connector is L8, where 3mm≤L7≤8mm and 7mm≤L8≤13mm.

19. The secondary battery as claimed in claim 15, wherein, The secondary battery also includes electrolyte sealed in the packaging bag, and the peel strength between the third insulating member and the tab is greater than 0.08 N / mm.

20. The secondary battery as claimed in claim 15, wherein, The first insulating component, the second insulating component, and the third insulating component all include a base layer and an adhesive layer, wherein the adhesive layer is connected to the base layer; The base layer includes one or a combination of several of the following: polyethylene terephthalate, polyimide, polyester film, polyethylene film, nonwoven fabric, and foam. The adhesive layer includes one or more of the following: acrylic system, rubber system, styrene-isoprene-styrene, isooctyl acrylate, octyl methacrylate, isooctyl methacrylate, isoprene, styrene, butyl acrylate, polyacrylic acid, polyacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, and polymethyl methacrylate.

21. An electronic device, wherein, Includes the secondary battery as described in any one of claims 1 to 20.

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