Secondary battery and electronic device

Abstract

A secondary battery and an electronic device. The secondary battery comprises a metal case, a pole, an electrode assembly, a first tab lead and a first insulating member. The metal case comprises a top wall, and a first wall and a second wall which are connected to two sides of the top wall. The pole is provided on the top wall and insulated from the metal case. The electrode assembly comprises a main body, and a first tab and a second tab connected to the main body, the main body and the top wall are arranged opposite to each other in a second direction, and the first tab extends from the main body toward the top wall. The first tab lead comprises a first bending point, and a first segment and a second segment located on two sides of the first bending point. In a first direction, the first wall is closer to the first bending point than the second wall. The first insulating member is provided between the first wall and the first bending point. In the first direction, the projection of the first bending point is located within the projection of the first insulating member, and at least part of the projection of the main body overlaps the projection of the first insulating member. The safety performance of the secondary battery is improved.

Description

Secondary battery and electronic device TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, in particular to a secondary battery and an electronic device. BACKGROUND

[0002] The metal shell and the pole of the secondary battery are respectively connected with the electrode assembly and have opposite polarities. In the existing secondary battery, the pole and the electrode assembly are connected through the tab lead, the bending point of the tab lead is easy to contact the metal shell to cause short circuit, and the safety performance of the secondary battery is reduced.

[0003] SUMMARY

[0004] In view of the above situation, the present application provides a secondary battery, which is beneficial to improve the safety performance.

[0005] The embodiment of the present application provides a secondary battery, which comprises a metal shell, a pole, an electrode assembly, a first tab lead and a first insulating piece. The metal shell comprises a top wall and first and second walls connected to two sides of the top wall, the first and second walls are oppositely arranged along a first direction, and the first direction is the thickness direction of the secondary battery. The pole is arranged on the top wall and is insulated from the metal shell. The electrode assembly is accommodated in the metal shell, and the electrode assembly comprises a main body and first and second tabs connected to the main body. The main body and the top wall are oppositely arranged along a second direction, and the second direction is perpendicular to the first direction. The first tab extends from one side of the main body towards the top wall. The first tab comprises a first part and a second part, the first part is located on the side of the main body towards the top wall, and the second part is bent from one end of the first part adjacent to the second wall towards the side of the first part away from the main body. The polarities of the first and second tabs are opposite, and the second tab is electrically connected to the metal shell. The first tab lead comprises a first bending point and first and second segments located on both sides of the first bending point, the first segment is connected between the first bending point and the pole, the second segment is connected between the first bending point and the first tab, and at least part of the second part overlaps with the second segment. Along the first direction, the first wall is closer to the first bending point than the second wall. The first insulating piece is arranged between the first wall and the first bending point, along the first direction, the projection of the first bending point is located in the projection of the first insulating piece, and the projection of at least part of the main body overlaps with the projection of the first insulating piece.

[0006] In the above-mentioned secondary battery, the first wall is closer to the first bending point than the second wall, which causes the first wall to be more likely to contact the first tab lead than the second wall. By arranging the first insulating piece between the first wall and the first bending point, along the first direction, the projection of the first bending point is located in the projection of the first insulating piece, and the projection of at least part of the main body overlaps with the projection of the first insulating piece, so as to reduce the risk of short circuit caused by the contact of the first bending point and the second segment with the first wall, thereby improving the safety performance of the secondary battery.

[0007] In some embodiments of the present application, the first insulating member comprises a first adhesive layer facing away from the first wall, the first adhesive layer adhering to and covering the first bending point and at least part of the surface of the main body facing the first wall. The first adhesive layer adhering to and covering the first bending point is to reduce the risk of the first bending point deviating from the first insulating member and contacting the first wall to cause short circuit, thereby improving the safety performance of the secondary battery. The first adhesive layer adhering to and covering at least part of the surface of the main body facing the first wall is to compensate the pressure of the part of the main body adjacent to the top wall by the weight of the first insulating member during formation of the secondary battery, thereby reducing the risk of lithium precipitation caused by uneven formation pressure of the part of the main body adjacent to the top wall.

[0008] In some embodiments of the present application, the first insulating member further comprises a second adhesive layer facing the first wall, the second adhesive layer adhering to the first wall to improve the stability of the position of the first insulating member and reduce the risk of the first bending point and the second segment contacting the first wall to cause short circuit, thereby improving the safety performance of the secondary battery. The second adhesive layer is hot melt adhesive, which has strong buffering performance and is conducive to improving the drop resistance of the secondary battery.

[0009] In some embodiments of the present application, the secondary battery further comprises a second insulating member and a third insulating member, a surface of the second insulating member adhering to a surface of the first tab lead wire facing the first wall, and a surface of the third insulating member adhering to a surface of the first tab lead wire facing the second wall. The second insulating member is used to cooperate with the first insulating member to reduce the risk of the first tab lead wire contacting the first wall to cause short circuit, thereby improving the safety performance of the secondary battery. The third insulating member is used to reduce the risk of the first tab lead wire contacting the second wall to cause short circuit, thereby improving the safety performance of the secondary battery.

[0010] In some embodiments of the present application, the first adhesive layer and the surface of the main body facing the first wall have a first overlapping part. In the second direction, the length L1 of the first overlapping part satisfies the following relationship: 5mm≤L1≤10mm, which is conducive to compensating the pressure of the part of the main body adjacent to the top wall by the weight of the first insulating member during formation of the secondary battery, and is conducive to improving the cycle performance and energy density of the secondary battery.

[0011] In some embodiments of the present application, 7mm≤L1≤8mm, which is further conducive to compensating the pressure of the part of the main body adjacent to the top wall by the weight of the first insulating member during formation of the secondary battery, and is conducive to improving the cycle performance and energy density of the secondary battery.

[0012] In some embodiments of this application, the first adhesive layer also adheres to and covers at least a portion of the pole post, and the first adhesive layer and the pole post have a second overlapping portion. Along the second direction, the length L2 of the second overlapping portion satisfies the following relationship: 0.1mm≤L2≤0.25mm, which is beneficial to improving the stability of the connection between the first insulating member and the pole post, and also beneficial to the length adaptation of the first insulating member and the pole post within the metal housing.

[0013] In some embodiments of this application, 0.2mm≤L2≤0.25mm is used to further improve the stability of the connection between the first insulating member and the pole post, and to facilitate the length adaptation of the first insulating member and the pole post within the metal housing, thus making packaging easier.

[0014] In some embodiments of this application, the main body includes a negative electrode sheet, a separator, and a positive electrode sheet stacked sequentially along a first direction. Viewed along the first direction, the negative electrode sheet includes two protrusions extending from both sides of the positive electrode sheet in a third direction. The first direction, the second direction, and the third direction are perpendicular to each other. Along the first direction, the projections of the two edges of the first overlapping portion in the third direction are respectively located within the projections of the two protrusions. This has two advantages: First, it facilitates a more uniform pressure distribution from the first insulating member on the portion of the main body adjacent to the top wall, reducing the risk of lithium plating due to uneven formation pressure on the portion of the main body adjacent to the top wall. Second, it reduces the risk of interference between the weld between the first insulating member and the metal casing.

[0015] In some embodiments of this application, the positive electrode includes a positive current collector and a positive active material layer connected to the positive current collector. The positive current collector includes a first region and a second region connected together. Along a second direction, the first region is closer to the top wall than the second region, and the thickness of the positive active material layer in the first region is less than the thickness of the positive active material layer in the second region, thereby reducing the risk of lithium plating at the edge of the positive electrode. The thickness difference between the positive active material layers in the first region and the second region is adapted to the thickness of the first insulating member. The first insulating member can also compensate for the thickness difference of the positive electrode in the first direction, thereby improving the structural stability of the electrode assembly.

[0016] In some embodiments of this application, the peel strength S1 between the first adhesive layer and the surface of the main body facing the first wall satisfies the following relationship: S1≥0.1N / mm, which is beneficial to compensate for the pressure of the part of the main body near the top wall by the weight of the first insulating member during the formation of the secondary battery, and reduce the risk of lithium plating caused by uneven formation pressure in the part of the main body near the top wall.

[0017] In some embodiments of this application, the peel strength S2 between the second adhesive layer and the first wall satisfies the following relationship: 0.5 N / mm ≤ S2 ≤ 2.0 N / mm. This is beneficial to improving the connection stability between the second adhesive layer and the first wall, and also beneficial to improving the energy density of the secondary battery, as well as reducing the risk of breakage due to stress concentration at the bonding points between the first tab lead or the main body and the first adhesive layer.

[0018] In some embodiments of this application, the thickness H1 of the first insulating member satisfies the following relationship: 10μm≤H1≤40μm, which is beneficial to improving the structural strength of the first insulating member and to improving the energy density of the secondary battery.

[0019] In some embodiments of this application, the housing is made of stainless steel, the first tab is positive and the second tab is negative; or the housing is made of aluminum, the first tab is negative and the second tab is positive. This arrangement makes the material of the metal housing similar in potential to the material potential of the current collector on the electrode, thereby improving the stability of the electrical connection.

[0020] In some embodiments of this application, the second tab extends from the main body towards the top wall. The secondary battery also includes a second tab lead, one end of which is connected to the second tab, and the other end of which is connected to the top wall and spaced apart from the terminal post. A first notch is provided at the corner of the first insulating member near the second tab lead. A portion of the second tab lead is exposed through the first notch.

[0021] In some embodiments of this application, the first electrode includes a plurality of first electrode units, one end of the plurality of first electrode units is arranged along a first direction and connected to the main body, and the other ends of the plurality of first electrode units are brought together to form a first part and a second part arranged sequentially.

[0022] Embodiments of this application also provide an electronic device, which further includes any of the secondary batteries described in the above embodiments.

[0023] In the aforementioned secondary battery and electronic device, the first wall is closer to the first bend point than the second wall, making it easier for the first wall to contact the first electrode lead. By disposing a first insulating member between the first wall and the first bend point, the projection of the first bend point lies within the projection of the first insulating member along the first direction, and at least a portion of the main body's projection overlaps with the projection of the first insulating member. This reduces the risk of short circuits caused by contact between the first bend point and the second segment with the first wall, thereby improving the safety performance of the secondary battery. Attached Figure Description

[0024] Figure 1 is a schematic diagram of the secondary battery structure viewed along a third direction in one embodiment of this application.

[0025] Figure 2 is a schematic diagram of the secondary battery viewed along the first direction in one embodiment of this application.

[0026] Figure 3 is a schematic diagram of the structure of the first insulating element in the secondary battery in another embodiment of this application.

[0027] Figure 4 is a schematic diagram of the structure of the first insulating element in a secondary battery according to one embodiment of this application.

[0028] Figure 5 is a schematic diagram of the structure of the second insulating element in a secondary battery according to one embodiment of this application.

[0029] Figure 6 is a schematic diagram of the structure of a secondary battery assembled into an electronic device in one embodiment of this application.

[0030] Key Component Symbols: Secondary Battery 100, Electronic Device 200, Metal Casing 10, Top Wall 11, First Wall 12, Second Wall 13, Terminal Post 20, Electrode Assembly 30, Main Body 31, Negative Electrode 311, Protrusion 311a, Separator 312, Positive Electrode 313, Positive Current Collector 313a, First Region 3131, Second Region 3132, Positive Active Material Layer 313b, First Tab 32, First Tab Unit 321, First Part 32a, Second Part 32b, Second Tab 33, First Tab Lead 40, First Bending Point 41, First Segment 42, Second Segment 43, First Insulator 50, First Adhesive Layer 51, First Overlapping Part 51a, Second Overlapping Part 51b, Second Adhesive Layer 52, Substrate Layer 53, First Side50a Second side 50b Third side 50c Fourth side 50d First notch 50e First bevel 50f Second notch 50g First extension edge 50h Second extension edge 50i Second tab lead 60 Second insulator 70 Third insulator 80 First direction Z Second direction X Third direction Y

[0031] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0033] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have a component that is centrally located. When a component is considered to be "set" on another component, it can be directly set on the other component or may also have a component that is centrally located.

[0034] When one value is considered "equal" to another, it means that they are equal within a set deviation range, which is within 5%. In other words, if at least one of the two values ​​fluctuates within the set deviation range, they are considered approximately equal even if their values ​​are not equal. Similarly, when one value is considered to have a "1:1" ratio with another, it means that they are equal within a set deviation range, which is within 5%. Again, if at least one of the two values ​​fluctuates within the set deviation range, they are considered equal in ratio even if their values ​​are not equal.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. The term "overlap" as used herein refers to the overlapping of the projected portions of two components or the coincidence of the projected portions of two components.

[0036] This application provides a secondary battery, which includes a metal casing, terminals, an electrode assembly, a first tab lead, and a first insulating member. The metal casing includes a top wall and a first wall and a second wall connected to both sides of the top wall. The first wall and the second wall are disposed opposite each other along a first direction, which is the thickness direction of the secondary battery. The terminals are disposed on the top wall and insulated from the metal casing. The electrode assembly is housed within the metal casing and includes a main body and a first tab and a second tab connected to the main body. The main body and the top wall are disposed opposite each other along a second direction, which is perpendicular to the first direction. The first tab extends from the side of the main body facing the top wall. The first tab includes a first portion and a second portion. The first portion is located on the side of the main body facing the top wall, and the second portion bends from one end of the first portion adjacent to the second wall toward the side of the first portion away from the main body. The first tab and the second tab have opposite polarities, and the second tab is electrically connected to the metal casing. The first electrode lead includes a first bend point and a first segment and a second segment located on both sides of the first bend point. The first segment connects the first bend point and the electrode post, and the second segment connects the first bend point and the first electrode, with at least a portion of the second segment overlapping the first electrode lead. Along a first direction, the first wall is closer to the first bend point than the second wall. A first insulating member is disposed between the first wall and the first bend point. Along the first direction, the projection of the first bend point lies within the projection of the first insulating member, and at least a portion of the projection of the first insulating member overlaps with the projection of the first insulating member.

[0037] In the aforementioned secondary battery, the first wall is closer to the first bend point than the second wall, making it easier for the first wall to contact the first electrode lead. By placing a first insulating member between the first wall and the first bend point, the projection of the first bend point lies within the projection of the first insulating member along the first direction, and at least a portion of the main body's projection overlaps with the projection of the first insulating member. This reduces the risk of short circuits caused by contact between the first bend point and the second segment with the first wall, thereby improving the safety performance of the secondary battery.

[0038] The embodiments of this application will be further described below with reference to the accompanying drawings.

[0039] Please refer to Figures 1 and 2 together. One embodiment of this application provides a secondary battery 100. After the secondary battery 100 is discharged, the active material can be activated by charging and it can continue to be used. The secondary battery 100 includes a metal casing 10, terminals 20, electrode assembly 30, and a first tab lead 40.

[0040] The metal casing 10 includes a top wall 11 and a first wall 12 and a second wall 13 connected to both sides of the top wall 11. The first wall 12 and the second wall 13 are disposed opposite each other along a first direction Z, which is the thickness direction of the secondary battery 100. The metal casing 10 contains a metallic element and has electrical conductivity. Optionally, the metallic element includes at least one selected from Mg, Al, Zn, Fe, Sn, Cu, Ag, Pt, Au, and Mn.

[0041] The electrode post 20 is disposed on the top wall 11 and is insulated from the metal housing 10. The electrode assembly 30 is housed within the metal housing 10 and includes a main body 31 and a first electrode tab 32 and a second electrode tab 33 connected to the main body 31. The main body 31 is used to convert chemical energy into electrical energy, and the first electrode tab 32 and the second electrode tab 33 have opposite polarities. The main body 31 includes a positive electrode sheet, a separator membrane, and a negative electrode sheet arranged sequentially. Optionally, the positive electrode sheet, the separator membrane, and the negative electrode sheet are in a wound structure or a stacked structure.

[0042] The main body 31 and the top wall 11 are arranged opposite each other along a second direction X. The second direction X is perpendicular to the first direction Z. Optionally, the second direction X is the length direction of the secondary battery 100.

[0043] The first electrode tab 32 extends from the side of the main body 31 toward the top wall 11 to facilitate electrical connection with the electrode post 20 via the first electrode tab lead 40. Specifically, the first electrode tab 32 includes a first portion 32a and a second portion 32b. The first portion 32a is located on the side of the main body 31 toward the top wall 11, and the second portion 32b bends from the end of the first portion 32a adjacent to the second wall 13 toward the side of the first portion 32a away from the main body 31. The first portion 32a and the second portion 32b form an arc-shaped structure, with the convex side of the arc-shaped structure facing the second wall 13 and the concave side of the arc-shaped structure facing the first wall 12.

[0044] The second tab 33 is electrically connected to the metal housing 10 so that the polarities of the metal housing 10 and the pole 20 are opposite, thereby facilitating the electrical connection between the metal housing 10 and the pole 20 and an external circuit (e.g., a protection board). Optionally, the second tab 33 may directly contact the metal housing 10 to achieve electrical connection, or the second tab 33 may contact the metal housing 10 through a tab lead or other conductive element to achieve electrical connection.

[0045] The first tab lead 40 includes a first bend point 41 and a first segment 42 and a second segment 43 located on both sides of the first bend point 41. The first bend point 41 is the point where the first tab lead 40 bends and is furthest from the second wall 13 in the first direction Z. The first segment 42 connects the first bend point 41 and the pole post 20. The second segment 43 connects the first bend point 41 and the first tab 32, and at least a portion of the second portion 32b overlaps with the second segment 43. The first segment 42 and the second segment 43 form an arc-shaped structure, with the convex side of the arc-shaped structure facing the first wall 12 and the concave side facing the second wall 13. The bend in the second segment 43 increases its extension length, thereby facilitating an increase in the connection area between the second segment 43 and the first tab 32. Along the first direction Z, the first wall 12 is closer to the first bend point 41 than the second wall 13, making it easier for the first wall 12 to contact the first tab lead 40.

[0046] Understandably, the first electrode lead 40 can be bent multiple times to form multiple bending points and multiple segments. The point that is farthest from the second wall 13 in the first direction Z among the multiple bending points is defined as the first bending point 41.

[0047] The first insulating member 50 is disposed between the first wall 12 and the first bending point 41. Along the first direction Z, the projection of the first bending point 41 lies within the projection of the first insulating member 50, and at least a portion of the projection of the main body 31 overlaps with the projection of the first insulating member 50. The first insulating member 50 is used to reduce the risk of short circuits caused by the contact between the first bending point 41 and the second segment 43 and the first wall 12, thereby improving the safety performance of the secondary battery 100.

[0048] In the aforementioned secondary battery 100, the first wall 12 is closer to the first bending point 41 than the second wall 13, making it easier for the first wall 12 to contact the first electrode lead 40. By disposing of the first insulating member 50 between the first wall 12 and the first bending point 41, along the first direction Z, the projection of the first bending point 41 lies within the projection of the first insulating member 50, and at least a portion of the projection of the main body 31 overlaps with the projection of the first insulating member 50. This reduces the risk of a short circuit caused by contact between the first bending point 41 and the second segment 43 and the first wall 12, thereby improving the safety performance of the secondary battery 100.

[0049] Referring to Figure 2, in some embodiments, the secondary battery 100 further includes a second tab lead 60. The second tab 33 extends from the body 31 toward the top wall 11, meaning the first tab 32 and the second tab 33 are located on the same side of the body 31. One end of the second tab lead 60 is connected to the second tab 33, and the other end of the second tab lead 60 is connected to the top wall 11 and spaced apart from the terminal post 20.

[0050] Along the first direction Z, at least part of the projection of the second tab lead 60 overlaps with the projection of the first insulating member 50, so as to reduce the risk of short circuit caused by the second tab lead 60 contacting the first wall 12, thereby improving the safety performance of the secondary battery 100.

[0051] It is understood that in other embodiments, the first tab 32 and the second tab 33 are located on different sides of the main body 31. Correspondingly, the second tab lead 60 is connected to the part of the metal housing 10 that is separate from the first wall 12. At this time, along the first direction Z, the projection of the second tab lead 60 overlaps with or is separate from the projection of the first insulating member 50.

[0052] Please continue to refer to Figure 1. In some embodiments, the main body 31 includes a negative electrode 311, a separator 312 and a positive electrode 313 stacked sequentially along the first direction Z. A first tab 32 is connected to the positive electrode 313 and a second tab 33 is connected to the negative electrode 311.

[0053] The first electrode 32 includes a plurality of first electrode units 321. One end of the plurality of first electrode units 321 is arranged along the first direction Z and connected to the main body 31. Each first electrode unit 321 is connected to a positive electrode plate 313. The other ends of the plurality of first electrode units 321 converge to form a first part 32a and a second part 32b arranged sequentially.

[0054] Optionally, the overlapping portion of the second part 32b and the second segment 43 has solder marks to improve the stability of the connection between the first tab 32 and the second segment 43.

[0055] Optionally, the first electrode unit 321 and the positive electrode plate 313 are integrally formed.

[0056] It is understood that in other embodiments, the second part 32b and the first electrode lead 40 are integrally formed, that is, when the number of first electrode units 321 is small, the first electrode 32 is directly connected to the pole post 20 after being bent. Optionally, the number of first electrode units 321 is 1, 2, 3, 4, 7 mm, or one of other natural numbers except 0.

[0057] Understandably, the second electrode 33 has a similar structure to the first electrode 32, also including multiple second electrode units. One end of each second electrode unit is arranged along the first direction Z and connected to the main body 31, and each second electrode unit is connected to a negative electrode plate. The other ends of the multiple second electrode units converge and are electrically connected to the metal housing 10.

[0058] It is understood that in other embodiments, the first tab 32 is connected to the negative electrode 311, and the second tab 33 is connected to the positive electrode 313.

[0059] In some embodiments, the current collector of the negative electrode 311 is made of copper foil, and the current collector of the positive electrode 313 is made of aluminum foil. The material of the metal housing 10 is related to the material of the electrode electrically connected to the metal housing 10. By setting the material potential of the metal housing 10 to be similar to that of the current collector of the electrode, the stability of the electrical connection is improved. Optionally, the metal housing 10 is made of stainless steel, with the first tab 32 being positive and the second tab 33 being negative; or the metal housing 10 is made of aluminum, with the first tab 32 being negative and the second tab 33 being positive.

[0060] Referring to Figures 1 and 2, in some embodiments, the first insulating member 50 includes a first adhesive layer 51 facing away from the first wall 12. The first adhesive layer 51 adheres to and covers the first bending point 41 to reduce the risk of a short circuit caused by the first bending point 41 deviating from the first insulating member 50 and contacting the first wall 12, thereby improving the safety performance of the secondary battery 100. The first adhesive layer 51 also adheres to and covers at least a portion of the surface of the body 31 facing the first wall 12, so that during the formation of the secondary battery 100, the weight of the first insulating member 50 compensates for the pressure on the portion of the body 31 adjacent to the top wall 11, reducing the risk of lithium plating caused by uneven formation pressure on the portion of the body 31 adjacent to the top wall 11.

[0061] In some embodiments, the first adhesive layer 51 and the surface of the main body 31 facing the first wall 12 have a first overlapping portion 51a. Along the second direction X, the length L1 of the first overlapping portion 51a satisfies the following relationship: 5mm ≤ L1 ≤ 10mm. When L1 is too small (less than 5mm), the connection area between the first adhesive layer 51 and the surface of the main body 31 facing the first wall 12 is relatively small, which is detrimental to compensating for the pressure on the portion of the main body 31 adjacent to the top wall 11 by the weight of the first insulating member 50 during the formation of the secondary battery 100. When L1 is too large (greater than 10mm), the area of ​​the main body 31 facing the first wall 12 that is immersed in the electrolyte is reduced, leading to a decrease in the cycle performance and energy density of the secondary battery 100. By limiting 5mm ≤ L1 ≤ 10mm, it is beneficial to compensate for the pressure on the portion of the main body 31 adjacent to the top wall 11 by the weight of the first insulating member 50 during the formation of the secondary battery 100, and it is also beneficial to improve the cycle performance and energy density of the secondary battery 100.

[0062] Optionally, L1 can be any value within the range of 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.1mm, 7.2mm, 7.3mm, 7.4mm, 7.5mm, 7.6mm, 7.7mm, 7.8mm, 7.9mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, and any other value within the range of 5mm≤L1≤10mm.

[0063] Furthermore, 7mm≤L1≤8mm is more conducive to compensating for the pressure on the part of the main body 31 adjacent to the top wall 11 by the weight of the first insulating member 50 during the formation of the secondary battery 100, and is also conducive to improving the cycle performance and energy density of the secondary battery 100.

[0064] Referring to Figures 1 and 2, in some embodiments, viewed along the first direction Z, the negative electrode 311 includes two protrusions 311a extending from both sides of the positive electrode 313 in the third direction Y, to reduce the risk of lithium plating on the negative electrode 311. The first direction Z, the second direction X, and the third direction Y are perpendicular to each other. Optionally, the third direction Y is the width direction of the secondary battery 100.

[0065] Along the first direction Z, the projections of the two edges of the first overlapping portion 51a in the third direction Y lie within the projections of the two protrusions 311a, respectively. Firstly, this facilitates a more uniform pressure distribution from the first insulating member 50 on the portion of the main body 31 adjacent to the top wall 11, reducing the risk of lithium plating due to uneven formation pressure in this area. Secondly, it helps reduce the risk of interference between the weld between the first insulating member 50 and the metal casing 10.

[0066] Please refer to Figures 1 and 2 together. In some embodiments, along the first direction Z, at least part of the projection of the pole post 20 overlaps with the projection of the first insulating member 50 to reduce the risk of short circuit caused by the first segment 42 contacting the first wall 12, thereby improving the safety performance of the secondary battery 100.

[0067] The first adhesive layer 51 also adheres to and covers at least a portion of the terminal post 20. The first adhesive layer 51 and the terminal post 20 have a second overlapping portion 51b. Along the second direction X, the length L2 of the second overlapping portion 51b satisfies the following relationship: 0.1mm ≤ L2 ≤ 0.25mm. When L2 is too small (less than 0.1mm), the connection area between the first adhesive layer 51 and the terminal post 20 is easily too small, causing the first insulating member 50 to deviate from the terminal post 20. When L2 is too large (greater than 0.25mm), it is not conducive to the length adaptation of the terminal post 20 within the metal housing 10, thus affecting the packaging. By limiting 0.1mm ≤ L2 ≤ 0.25mm, it is beneficial to improve the stability of the connection between the first insulating member 50 and the terminal post 20, and also beneficial to the length adaptation of the first insulating member 50 and the terminal post 20 within the metal housing 10, facilitating packaging.

[0068] Optionally, L2 can be any value within the range of 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, and any other value within the range of 0.1mm≤L2≤0.25mm.

[0069] Furthermore, 0.2mm≤L2≤0.25mm is beneficial to improving the stability of the connection between the first insulating member 50 and the pole post 20, and also facilitates the length adaptation of the first insulating member 50 and the pole post 20 within the metal housing 10, making packaging easier.

[0070] In some embodiments, the first adhesive layer 51 is a pressure-sensitive adhesive, which is made of one or more of the following: natural rubber, styrene-butadiene rubber, isoprene rubber, styrene-polybutadiene-styrene block copolymer, hydrogenated styrene-polybutadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-polyisoprene-styrene block copolymer, polyisobutylene, amorphous α-olefin copolymer, petroleum resin, terpene resin, and rosin resin.

[0071] In some embodiments, the peel strength S3 between the first adhesive layer 51 and the first bending point 41 satisfies the following relationship: S3 ≥ 0.1 N / mm. When S3 is too small (less than 0.1 N / mm), the first bending point 41 is prone to deviating from the first insulating member 50 and contacting the first wall 12, resulting in a short circuit. By limiting S3 to ≥ 0.1 N / mm, the risk of the first bending point 41 deviating from the first insulating member 50 and contacting the first wall 12, resulting in a short circuit, can be reduced.

[0072] Optionally, S3 can be any value within the range of 0.1 N / mm, 0.2 N / mm, 0.3 N / mm, 0.4 N / mm, 0.5 N / mm, 0.6 N / mm, 0.7 N / mm, 0.8 N / mm, 0.9 N / mm, 1 N / mm, and any other value within the range of S3 ≥ 0.1 N / mm.

[0073] In some embodiments, S3 ≤ 1 N / mm. When S3 is too large (greater than 1 N / mm), the stress on the first bending point 41 is likely to be too high, leading to damage to the first bending point 41. By limiting S3 to ≤ 1 N / mm, it is beneficial to reduce the stress on the first bending point 41.

[0074] In some embodiments, the peel strength S1 between the first adhesive layer 51 and the surface of the body 31 facing the first wall 12 satisfies the following relationship: S1 ≥ 0.1 N / mm. When S1 is too small (less than 0.1 N / mm), the connection stability between the first adhesive layer 51 and the surface of the body 31 facing the first wall 12 is poor, which is not conducive to compensating for the pressure on the part of the body 31 adjacent to the top wall 11 by the weight of the first insulating member 50 during the formation of the secondary battery 100. By limiting S1 to ≥ 0.1 N / mm, it is beneficial to compensate for the pressure on the part of the body 31 adjacent to the top wall 11 by the weight of the first insulating member 50 during the formation of the secondary battery 100, thereby reducing the risk of lithium plating caused by uneven formation pressure on the part of the body 31 adjacent to the top wall 11.

[0075] Optionally, S1 can be any value within the range of 0.1 N / mm, 0.2 N / mm, 0.3 N / mm, 0.4 N / mm, 0.5 N / mm, 0.6 N / mm, 0.7 N / mm, 0.8 N / mm, 0.9 N / mm, 1 N / mm, and any other value within the range of S1 ≥ 0.1 N / mm.

[0076] In some embodiments, S1 ≤ 1 N / mm. When S1 is too large (greater than 1 N / mm), excessive adhesive can easily clog the pores on the surface of the body 31 facing the first wall 12, causing lithium plating and reducing the cycle performance of the secondary battery 100. Limiting S1 to ≤ 1 N / mm is beneficial for improving the cycle performance of the secondary battery 100.

[0077] Please refer to Figures 1 and 2 together. In some embodiments, the first insulating member 50 further includes a second adhesive layer 52 facing the first wall 12. The second adhesive layer 52 is bonded to the first wall 12 to improve the positional stability of the first insulating member 50, reduce the risk of short circuit caused by the first bending point 41 and the second segment 43 contacting the first wall 12, and thus improve the safety performance of the secondary battery 100.

[0078] In some embodiments, the second adhesive layer 52 is a hot melt adhesive, which has strong cushioning properties, thus improving the drop resistance of the secondary battery 100. The hot melt adhesive layer is made of one or more of the following: hydrogenated styrene block copolymer, modified hydrogenated styrene block copolymer, hydrogenated petroleum resin II, antioxidant, styrene, isoprene, polymethyl methacrylate, polyacrylic acid, polyacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, ethylene-vinyl acetate copolymer, and polyimide.

[0079] In some embodiments, the peel strength S2 between the second adhesive layer 52 and the first wall 12 satisfies the following relationship: 0.5 N / mm ≤ S2 ≤ 2.0 N / mm. When S2 is too small (less than 0.5 N / mm), the connection stability between the second adhesive layer 52 and the first wall 12 is poor; when S2 is too large (greater than 2 N / mm), excessive adhesive can increase the thickness of the second adhesive layer 52, leading to a decrease in the energy density of the secondary battery 100. Furthermore, during the drop of the secondary battery 100, the bonding area between the first tab lead 40 or the main body 31 and the first adhesive layer 51 is prone to breakage due to stress concentration. By limiting 0.5 N / mm ≤ S2 ≤ 2.0 N / mm, it is beneficial to improve the connection stability between the second adhesive layer 52 and the first wall 12, and also beneficial to improve the energy density of the secondary battery 100, as well as reduce the risk of breakage due to stress concentration at the bonding area between the first tab lead 40 or the main body 31 and the first adhesive layer 51.

[0080] Optionally, S2 can be any value within the range of 0.5 N / mm, 1 N / mm, 1.5 N / mm, 2 N / mm, and 0.5 N / mm ≤ S2 ≤ 2.0 N / mm.

[0081] In some embodiments, the first insulating member 50 further includes a substrate layer 53, and a first adhesive layer 51 and a second adhesive layer 52 are respectively disposed on both sides of the substrate layer 53. The substrate layer 53 may be selected from polyethylene terephthalate, co-extruded polypropylene, oriented polystyrene, thermoplastic polyurethane, polylactic acid, polyolefin, and polyimide.

[0082] For the first adhesive layer 51, the adhesive strength is adjusted by selecting different material types and / or qualities of the first adhesive layer 51, thereby adjusting the peel strength S1 and peel strength S3; for the second adhesive layer 52, the adhesive strength is adjusted by selecting different material types and / or qualities of the second adhesive layer 52, thereby adjusting the peel strength S2.

[0083] In some embodiments, the first insulating member 50 includes a first adhesive layer 51 and a second adhesive layer 52, which can also reduce the risk of damage to the body 31 due to movement within the metal housing 10.

[0084] Please refer to Figure 1. In some embodiments, the thickness H1 of the first insulating member 50 satisfies the following relationship: 10 μm ≤ H1 ≤ 40 μm. When H1 is too small (less than 10 μm), the structural strength of the first insulating member 50 is easily compromised; when H1 is too large (greater than 40 μm), the space occupied by the first insulating member 50 is easily increased, leading to a decrease in the energy density of the secondary battery 100. By limiting H1 to 40 μm, it is beneficial to improve the structural strength of the first insulating member 50 and to improve the energy density of the secondary battery 100.

[0085] Optionally, H1 can be any value in the range of 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, or any other value in the range of 10μm to 40μm.

[0086] Referring to Figure 1, in some embodiments, the positive electrode 313 includes a positive current collector 313a and a positive active material layer 313b connected to the positive current collector 313a. The positive current collector 313a includes a first region 3131 and a second region 3132 connected together. Along the second direction X, the first region 3131 is closer to the top wall 11 than the second region 3132, and the thickness of the positive active material layer 313b in the first region 3131 is less than the thickness of the positive active material layer 313b in the second region 3132, thereby reducing the risk of lithium plating at the edge of the positive electrode 313. The thickness difference between the positive active material layer 313b in the first region 3131 and the positive active material layer 313b in the second region 3132 is adapted to the thickness H1 of the first insulating member 50. The first insulating member 50 can also compensate for the thickness difference of the positive electrode 313 in the first direction Z, thereby improving the structural stability of the electrode assembly 30.

[0087] Referring to Figure 2, in some embodiments, the first tab 32 and the second tab 33 are located on the same side of the main body 31. One end of the second tab lead 60 is connected to the second tab 33, and the other end of the second tab lead 60 is connected to the top wall 11 and spaced apart from the pole post 20. Viewed along the first direction Z, the first insulating member 50 includes a first side 50a and a second side 50b arranged opposite each other along the second direction X, and a third side 50c and a fourth side 50d arranged opposite each other along the third direction Y. The first side 50a, the third side 50c, the second side 50b, and the fourth side 50d are connected end-to-end. The first side 50a connects the pole post 20 and the second tab lead 60, and the second side 50b connects to the surface of the main body 31 facing the first wall 12. Along the third direction Y, the third side 50c is located on the side of the second tab 33 away from the first tab 32, and the fourth side 50d is located on the side of the first tab 32 away from the second tab 33.

[0088] Referring to Figure 3, in some embodiments, the first insulating member 50 has a first notch 50e at a corner near the second tab lead 60. Along the first direction Z, the projection of the second tab lead 60 and the projection of the first notch 50e partially overlap, so that a portion of the second tab lead 60 is exposed from the first notch 50e. Specifically, the first insulating member 50 also includes a first inclined side 50f, which connects the first side 50a and the third side 50c, and is inclined relative to the first side 50a and the third side 50c. Viewed along the first direction Z, the first inclined side 50f passes through the second tab lead 60.

[0089] Referring to Figure 4, in some embodiments, the first insulating member 50 has a second notch 50g at a corner near the second tab lead 60. Along the first direction Z, the projection of the second tab lead 60 lies within the projection of the second notch 50g, so that the second tab lead 60 is exposed from the second notch 50g. Specifically, the first insulating member 50 includes a first extending edge 50h and a second extending edge 50i. The first extending edge 50h is connected to the first side edge 50a and extends along the second direction X, and the second extending edge 50i is connected to the third side edge 50c and extends along the third direction Y. The first extending edge 50h and the second extending edge 50i are interconnected. Viewed along the first direction Z, the first extending edge 50h is located between the second tab lead 60 and the first tab lead 40, and the second extending edge 50i passes through the second tab 33.

[0090] Referring to Figures 1 and 5, in some embodiments, the secondary battery 100 further includes a second insulating member 70 and a third insulating member 80. The surface of the second insulating member 70 is bonded to the surface of the first tab lead 40 facing the first wall 12. The second insulating member 70 cooperates with the first insulating member 50 to reduce the risk of short circuit caused by contact between the first tab lead 40 and the first wall 12, thereby improving the safety performance of the secondary battery 100. Specifically, the second insulating member 70 extends from the surface of the body 31 facing the first wall 12 to the portion of the first tab lead 40 adjacent to the terminal post 20. The second insulating member 70 also covers the connection (e.g., solder mark) between the second segment 43 and the first tab 32.

[0091] The surface of the third insulating member 80 is bonded to the surface of the first tab lead 40 facing the second wall 13. The third insulating member 80 is used to reduce the risk of short circuit caused by contact between the first tab lead 40 and the second wall 13, thereby improving the safety performance of the secondary battery 100. Specifically, the third insulating member 80 extends from the surface of the body 31 facing the second wall 13 to the portion of the first tab lead 40 adjacent to the terminal post 20, and the third insulating member 80 also covers the connection (e.g., solder mark) between the second section 43 and the first tab 32.

[0092] In some embodiments, viewed along the third direction Y, bending the first tab lead 40 increases the connection area between the first tab lead 40 and the first tab 32. Compared to extending the tab lead in the width direction of the battery to increase the connection area between the tab lead and the tab, this method is beneficial to reduce the space required for the first tab lead 40 in the third direction Y, thereby facilitating a reduction in the width of the secondary battery 100 in the third direction Y, so as to meet the size requirements of ultra-narrow batteries.

[0093] In some embodiments, the width of the secondary battery 100 along the third direction Y is 6 mm to 15 mm. Optionally, the width of the secondary battery 100 is one of 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, and any other value within the range of 6 mm to 15 mm.

[0094] Referring to Figure 6, one embodiment of this application also provides an electronic device 200, which includes the secondary battery 100 in any of the above embodiments. Optionally, the electronic device 200 may be a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, or power tool, etc.

[0095] In the aforementioned secondary battery 100 and electronic device 200, the first wall 12 is closer to the first bending point 41 than the second wall 13, making it easier for the first wall 12 to contact the first electrode lead 40. A first insulating member 50 is disposed between the first wall 12 and the first bending point 41. Along the first direction Z, the projection of the first bending point 41 lies within the projection of the first insulating member 50, and at least a portion of the projection of the main body 31 overlaps with the projection of the first insulating member 50. This reduces the risk of a short circuit caused by contact between the first bending point 41 and the second segment 43 and the first wall 12, thereby improving the safety performance of the secondary battery 100.

[0096] It should be noted that the peel strength between the first adhesive layer 51 and the first bending point 41, the peel strength between the first adhesive layer 51 and the surface of the main body 31 facing the first wall 12, and the peel strength between the second adhesive layer 52 and the first wall 12 are obtained by testing with a high-speed rail tensile testing machine according to GB / T2792-2014 "Test Method for Peel Strength of Adhesive Tape" (in this embodiment, the surface of the first adhesive layer 51 and the surface of the main body 31 facing the first wall 12 is taken as an example). The test process is as follows: the secondary battery is discharged to 0V, and then the secondary battery is disassembled. The first insulating part 50 and the part of the main body 31 facing the first wall 12 are removed as a whole, and the electrolyte on the surface is wiped with lint-free paper. Then, it is cut into strips of 5mm×10mm. Along the length of the sample, the surface of the first insulating part 50 facing away from the first adhesive layer 51 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 at the corresponding position on the high-speed rail tensile testing machine. The main body 31 of the specimen is pulled up, and the specimen is placed in the clamp and tightened. The angle between the pulled-up specimen and the steel plate in space is 180°. The clamp pulls the specimen at a speed of 50 mm / min ± 0.2 mm / s. The average tensile force in the stable area is recorded as the peel strength between the first adhesive layer 51 and the surface of the main body 31 facing the first wall 12, in N / mm. It can be understood that when testing the peel strength between the second adhesive layer 52 and the first wall 12, the first insulating component 50 and the first wall 12 are removed as a whole, cut into strip specimens, and tested according to the above test method.

[0097] Safety testing of secondary batteries: The secondary batteries were pretreated to 50% SOC at 25℃ and left to stand in a room temperature environment for 60 minutes. The voltage of the secondary batteries before the drop test was then measured. The secondary batteries were placed in a fixture and dropped from a height of 1m in a test environment of 20±5℃ at a speed of 7 revolutions / min for 700 revolutions (2 drops constitute 1 revolution). The voltage and internal resistance were recorded during the drop test. The measurement frequency was initially set at 100 revolutions (100, 200, 300, ..., 700), and the number of batteries tested was 100.

[0098] Judgment criteria: No fire, no explosion, no smoke, no leakage, and voltage drop <30mV.

[0099] The assembly process of a secondary battery 100 is as follows:

[0100] (1) Preparation of the negative electrode sheet: The negative electrode active materials artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) were mixed in a weight ratio of 96:1.5:2.5, and deionized water was added as a solvent to prepare a slurry with a weight percentage of 70 wt%, which was then stirred evenly. The slurry was uniformly coated on one surface of a 10 μm thick copper foil negative electrode current collector, leaving an empty foil area at the edge of the copper foil. The foil was dried at 110 °C to obtain a negative electrode sheet with a coating thickness of 150 μm on one side, partially coated with a negative electrode active material layer. The above steps were repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a coated area and an empty foil area. The negative electrode tabs were then cut using a mold.

[0101] (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 a 12 μm thick aluminum foil for the positive electrode current collector, leaving a blank foil area. The foil was then dried at 90 °C to obtain a positive electrode sheet with a positive active material layer thickness of 100 μm. The above coating steps were repeated on the other surface of the aluminum foil to obtain the positive electrode sheet. The positive electrode tabs were then cut using a mold.

[0102] (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.

[0103] (4) Preparation of the release membrane: A three-layer release membrane is adopted, which includes a first adhesive layer, a second substrate layer and a second adhesive layer stacked together. The second substrate layer is made of polyethylene (PE), and the first adhesive layer and the second adhesive layer contain one or more of the following: adhesive and boehmite.

[0104] (5) Electrode assembly preparation: The positive electrode sheet, the separator and the negative electrode sheet are stacked and arranged to obtain the bare cell. The stacked positive electrode empty foil is gathered and transferred to the electrode tab lead wire. The upper and lower surfaces of the transfer solder are covered with the second insulating component and the third insulating component, respectively. The stacked negative electrode empty foil is gathered and transferred to the electrode tab lead wire.

[0105] (6) Preparation of the metal casing: The dented stainless steel casing is placed in the assembly fixture with the dent facing upwards. The electrode assembly is placed in the dent, and the first insulating component covers the first bending point. Then, another flat stainless steel casing is placed on the electrode assembly with the dent facing downwards and welded. Electrolyte is injected into the assembled secondary battery. After vacuum sealing, standing, hot pressing, and shaping, the secondary battery is obtained. The dimensions of the secondary battery are: 20mm long, 7mm wide, and 3.0mm thick. In the first insulating component, the first adhesive layer is polyisobutylene, the second adhesive layer is hydrogenated styrene block copolymer, and the substrate layer is polyimide.

[0106] Table 1

[0107] (Comparative Examples 1-4 and Examples 1-5 are the same as those in Example 1, except for the parameters mentioned in Table 1.)

[0108] As can be seen from the comparison of Example 1 to Example 4, by setting the first insulating member 50 between the first wall 12 and the first bending point 41, along the first direction Z, the projection of the first bending point 41 is located within the projection of the first insulating member 50, and at least part of the projection of the main body 31 overlaps with the projection of the first insulating member 50, so as to reduce the risk of short circuit caused by the first bending point 41 and the second segment 43 contacting the first wall 12, thereby improving the safety performance of the secondary battery 100.

[0109] As can be seen from Examples 1-5, limiting the size to 10μm≤H1≤40μm can improve the pass rate of safety tests. It should be noted that Example 5 tends to result in a larger space occupied by the first insulating component 50, leading to a decrease in the energy density of the secondary battery 100.

[0110] Table 2

[0111] (Example 8 is the same as Example 1. Except for the parameters mentioned in Table 2, the parameters of Examples 6-7 and 9-19 are the same as those of Example 8.)

[0112] As can be seen from the comparison of Examples 6-11, limiting the length to 5mm≤L1≤10mm can improve the pass rate of safety tests. It should be noted that Example 11 tends to result in the first insulating component 50 occupying a larger space, leading to a decrease in the energy density of the secondary battery 100.

[0113] As can be seen from the comparison of Examples 8 and 12-15, by limiting S1 to ≥ 0.1 N / mm, the pass rate of safety tests can be improved.

[0114] As can be seen from the comparison of Examples 8 and 16-19, by limiting L2 to 0.1mm≤L2≤0.25mm, the pass rate of safety tests can be improved.

[0115] In addition, those skilled in the art may make other changes within the spirit of this application. Of course, all such changes made in accordance with the spirit of this application should be included within the scope disclosed in this application.

Claims

1. A secondary battery characterized by comprising: The secondary battery comprises: a metal shell comprising a top wall and a first wall and a second wall connected to two sides of the top wall, the first wall and the second wall are oppositely arranged along a first direction, the first direction is the thickness direction of the secondary battery; a pole arranged on the top wall and insulated from the metal shell; an electrode assembly accommodated in the metal shell, the electrode assembly comprises a main body and a first tab and a second tab connected to the main body, the main body and the top wall are oppositely arranged along a second direction, the second direction is perpendicular to the first direction, the first tab extends from the main body towards one side of the top wall, the first tab comprises a first part and a second part, the first part is located on the side of the main body towards the top wall, the second part is bent from one end of the first part adjacent to the second wall towards the side of the main body away from the first part, the polarity of the first tab and the second tab is opposite, and the second tab is electrically connected to the metal shell; a first tab lead wire comprising a first bending point and a first segment and a second segment located on both sides of the first bending point, the first segment is connected between the first bending point and the pole, the second segment is connected between the first bending point and the first tab, and at least part of the second part overlaps with the second segment, along the first direction, the first wall is closer to the first bending point than the second wall; a first insulating member arranged between the first wall and the first bending point, along the first direction, the projection of the first bending point is located within the projection of the first insulating member, and at least part of the projection of the main body overlaps with the projection of the first insulating member.

2. The secondary battery according to claim 1, wherein The first insulating member comprises a first adhesive layer facing away from the first wall, the first adhesive layer adheres and covers the first bending point and at least part of the surface of the main body towards the first wall.

3. The secondary battery according to any one of claims 1 to 2, wherein The first insulating member further comprises a second adhesive layer towards the first wall, the second adhesive layer is adhered to the first wall, and the second adhesive layer is a hot melt adhesive.

4. The secondary battery according to any one of claims 1 to 3, wherein The secondary battery further comprises a second insulating member and a third insulating member, the surface of the second insulating member is adhered to the surface of the first tab lead wire towards the first wall, and the surface of the third insulating member is adhered to the surface of the first tab lead wire towards the second wall.

5. The secondary battery according to claim 2, wherein The first adhesive layer and the surface of the main body towards the first wall have a first overlapping part, along the second direction, the length L1 of the first overlapping part satisfies the following relationship: 5mm≤L1≤10mm.

6. The secondary battery according to claim 5, wherein 7mm≤L1≤8mm.

7. The secondary battery according to any one of claims 5 to 6, wherein The first adhesive layer also adheres and covers at least part of the pole, the first adhesive layer and the pole have a second overlapping part, along the second direction, the length L2 of the second overlapping part satisfies the following relationship: 0.1mm≤L2≤0.25mm.

8. The secondary battery according to claim 7, wherein 0.2mm≤L2≤0.25mm.

9. The secondary battery according to any one of claims 5 to 6, wherein The main body comprises a negative electrode tab, a separator and a positive electrode tab stacked in sequence along the first direction, and the negative electrode tab comprises two protruding parts protruding out of both sides of the positive electrode tab in a third direction, the first direction, the second direction and the third direction being perpendicular to each other; In the first direction, projections of two edges of the first overlapping part in the third direction are respectively located within projections of two protruding parts.

10. The secondary battery according to claim 9, wherein The positive electrode tab comprises a positive electrode current collector and a positive electrode active material layer connected to the positive electrode current collector; The positive electrode current collector comprises a first region and a second region connected to each other, and in the second direction, the first region is closer to the top wall than the second region, and the thickness of the positive electrode active material layer of the first region is less than the thickness of the positive electrode active material layer of the second region.

11. The secondary battery according to claim 2, wherein The peeling strength S1 between the first adhesive layer and the surface of the main body facing the first wall satisfies the following relationship: S1≥0.1 N / mm.

12. The secondary battery according to claim 3, wherein The peeling strength S2 between the second adhesive layer and the first wall satisfies the following relationship: 0.5 N / mm≤S2≤2.0 N / mm.

13. The secondary battery according to any one of claims 1 to 12, wherein The thickness H1 of the first insulating part satisfies the following relationship: 10 μm≤H1≤40 μm.

14. The secondary battery according to any one of claims 1 to 13, wherein The shell is made of stainless steel, the first tab is of positive polarity, and the second tab is of negative polarity. Or the shell is made of aluminum, the first tab is of negative polarity, and the second tab is of positive polarity.

15. The secondary battery according to any one of claims 1 to 14, wherein The second tab extends from one side of the main body facing the top wall; The secondary battery further comprises a second tab lead wire, one end of the second tab lead wire being connected to the second tab, and the other end of the second tab lead wire being connected to the top wall and spaced apart from the pole column, and the first insulating part is provided with a first notch near the corner position of the second tab lead wire.

16. The secondary battery according to any one of claims 1 to 15, wherein The first tab comprises a plurality of first tab units, one end of the plurality of first tab units being arranged in the first direction and connected to the main body, and the other end of the plurality of first tab units being gathered and forming the first part and the second part arranged in sequence.

17. An electronic device, comprising: The electronic device comprises the secondary battery as claimed in any one of claims 1 to 16.

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