Secondary battery and electric device

Abstract

The application discloses a secondary battery and an electric device. The secondary battery comprises a shell, an electrode assembly, a first tab bundle, a first adapter tab and a first adhesive. The first tab bundle is accommodated in the shell, the first tab bundle is bent into a U shape, and the first tab bundle comprises a first part, a second part and a third part arranged in sequence. The first adapter tab comprises a first connecting part and a second connecting part, the first connecting part is connected with the first tab bundle, and the second connecting part is connected with the first connecting part; the second connecting part has a first surface. A first adhesive layer is arranged on the first surface, the first adhesive layer extends in a direction in which the second connecting part extends out of the shell, the first adhesive layer comprises a connecting part and an extending part arranged in sequence, and the connecting part is bonded to the shell and the first adapter tab. The first adhesive is bonded to the extending part and the electrode assembly. The secondary battery is beneficial to reducing the possibility of tearing of the first tab bundle.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of energy storage, and particularly relates to a secondary battery and an electric device. BACKGROUND

[0002] At present, the pole ears of the multi-pole-ear secondary battery are usually gathered into a pole ear bundle, the pole ear bundle is connected with a switching pole ear, and the switching pole ear extends out of the shell so as to facilitate the connection between the secondary battery and an external device. In order to reduce the occupation of the pole ear bundle to the head space of the secondary battery, the pole ear bundle is usually bent into a U shape, and the part of the switching pole ear extending out of the shell is located on one side of the bending position of the pole ear bundle. For such a secondary battery, when it falls, the electrode assembly moves in the shell, while the switching pole ear is relatively stationary relative to the shell, so that the pole ear bundle is repeatedly pulled and stretched, and the pole ear bundle is prone to tearing, which affects the performance of the secondary battery. SUMMARY

[0003] In view of the above situation, it is necessary to provide a secondary battery which is conducive to reducing the possibility of tearing of the pole ear.

[0004] A first aspect of embodiments of the present application provides a secondary battery, which comprises a shell, an electrode assembly, a first tab bundle, a first adapter tab and a first adhesive. The shell is a packaging bag, and the electrode assembly is accommodated in the shell. The first tab bundle is accommodated in the shell, and the first tab bundle comprises a plurality of first tabs, each of which is electrically connected to the electrode assembly, and the plurality of first tabs are stacked to form the first tab bundle. The first tab bundle is bent into a U shape, and the first tab bundle comprises a first portion, a second portion and a third portion arranged in sequence, the first portion is connected to the electrode assembly, the second portion connects the first portion and the third portion, and the first tab bundle is located on one side of the electrode assembly along a first direction, and the first direction is perpendicular to the thickness direction of the electrode assembly. The first adapter tab comprises a first connecting portion and a second connecting portion, the first connecting portion comprises a first end, the second connecting portion is connected to the first end, the first connecting portion is connected to the third portion, and the second connecting portion is connected to the first connecting portion, and part of the second connecting portion extends out of the shell; the second connecting portion is located on the same side of the electrode assembly along the thickness direction of the electrode assembly as the second portion; the second connecting portion has a first surface and a second surface oppositely arranged along the thickness direction thereof. The first adhesive layer is arranged on the first surface, and the first adhesive layer comprises a connecting portion and an extending portion connected to each other, the connecting portion adhesively connects the shell and the first adapter tab and forms a sealing portion, the extending portion is located in the shell and extends out of the shell along the direction in which the second connecting portion extends out of the shell, the length of the extending portion is L1, the third portion has a third surface facing the third portion along the first direction, and the distance from the sealing portion to the third surface along the first direction is A, and L1≥0.3A; the bending point of the second portion is the highest point of the second portion along the thickness direction of the electrode assembly. The first adhesive adhesively connects the extending portion and the electrode assembly along the direction in which the second connecting portion extends out of the shell, the length of the part of the first adhesive overlapping with the extending portion is L2, and 0.5L1≤L2≤L1; along the direction perpendicular to the direction in which the second connecting portion extends out of the shell, the width of the extending portion is W1, the width of the part of the first adhesive overlapping with the extending portion is W2, and 0.8W1≤W2≤W1.

[0005] In the secondary battery, the first adhesive adhesively connects the electrode assembly and the first adhesive layer, and the first adhesive layer is adhesively connected to the shell, which is conducive to improving the stability of the position of the electrode assembly relative to the shell, reducing the amplitude of the movement of the electrode assembly relative to the shell when the secondary battery falls, and thus reducing the degree of pulling of the first tab bundle and the possibility of tearing of the first tab bundle. Furthermore, 0.5L1≤L2≤L1 and 0.8W1≤W2≤W1 are provided, which is conducive to improving the stability of the adhesion between the first adhesive and the first adhesive layer and reducing the possibility of the first adhesive being disconnected from the first adhesive layer due to the pulling of the electrode assembly, so as to maintain the connection between the first adhesive layer and the electrode assembly when the secondary battery falls.

[0006] In one or more embodiments of the present application, the length of the portion of the adhesive electrode assembly of the first adhesive along the first direction is D, and D≥2mm. By setting D≥2mm, the portion of the first adhesive adhesive electrode assembly is not too short, which is conducive to improving the stability of the adhesion of the first adhesive to the electrode assembly.

[0007] In one or more embodiments of the present application, the length of the electrode assembly along the first direction is L3, and D≤0.5L3. By setting D≤0.5L3, the portion of the first adhesive adhesive electrode assembly is not too short, which is conducive to saving materials.

[0008] In one or more embodiments of the present application, along the first direction, the distance from the connecting part to the electrode assembly is L4, and 1.5mm≤L4≤2mm. By setting L4≥1.5mm, the distance from the connecting part to the electrode assembly is not too short, which is conducive to leaving space for setting the extension part between the connecting part and the electrode assembly; by setting L4≤2mm, the distance from the connecting part to the electrode assembly is not too large, which is conducive to improving the energy density of the secondary battery.

[0009] In one or more embodiments of the present application, the plurality of first tabs includes a first outer layer tab, and the first outer layer tab and the first adhesive layer are located on the same side of the electrode assembly along the thickness direction of the electrode assembly. The first outer layer tab includes a fourth surface, which is a surface of the first outer layer tab along its thickness direction, and a portion of the fourth surface faces the outside of the electrode assembly; and the first adhesive is adhered to the fourth surface and the extension part. By adhering the first adhesive to the first outer layer tab, it is conducive to reducing the possibility of tearing of the first outer layer tab; and by adhering the first adhesive to the fourth surface, it is convenient to adhere.

[0010] In one or more embodiments of the present application, L1≤A. By setting L1≤A, along the direction in which the second connecting part protrudes from the shell, the extension part of the first adhesive layer does not exceed the third surface, which is conducive to reducing the possibility of the first adhesive layer extruding the first tab bundle when the electrode assembly moves, thereby reducing the possibility of tearing of the first tab.

[0011] In one or more embodiments of the present application, along the thickness direction of the electrode assembly, the extension part overlaps the electrode assembly. In this way, it is conducive to reducing the possibility of the first adhesive layer extruding the first tab bundle when the electrode assembly moves, thereby reducing the possibility of tearing of the first tab.

[0012] In one or more embodiments of the present application, the thickness of the first adhesive is T1, and 11.2μm≤T1. By setting the thickness T1 of the first adhesive to be ≥11.2μm, the thickness of the first adhesive is not too thin, which is conducive to reducing the possibility of the first adhesive being broken by the electrode assembly being pulled.

[0013] In one or more embodiments of the present application, T1≤20.8μm. By setting T1≤20.8μm, the thickness of the first adhesive is not too thick, which is conducive to reducing the impact of the first adhesive on the thickness of the secondary battery.

[0014] In one or more embodiments of the present application, the secondary battery comprises a second adhesive layer, part of the second adhesive layer is arranged on the second surface and connects the shell and the second connecting portion, and along the first direction, part of the second adhesive layer is located between the shell and the first connecting portion. In this way, when the electrode assembly moves in the first direction within the shell, the second adhesive layer can provide cushioning for the electrode assembly to reduce the possibility of damage to the electrode assembly.

[0015] In one or more embodiments of the present application, the first connecting portion is welded to the third portion and forms a welding mark. The secondary battery further comprises a second adhesive, the second adhesive is adhered to the first portion, along the direction in which the second connecting portion extends out of the shell, at least part of the second adhesive is located between the first portion and the third portion, and in the thickness direction of the third portion, the second adhesive covers the welding mark. By arranging the second adhesive, it is conducive to reducing the risk of burrs formed during welding piercing the separator in the electrode assembly, thereby reducing the risk of short circuit of the secondary battery.

[0016] In one or more embodiments of the present application, the thickness of the first adhesive layer is T2, 56μm≤T2≤104μm. By setting T2≥56μm, the thickness of the first adhesive layer is not too small, which is conducive to improving the packaging strength of the first adhesive layer, thereby reducing the possibility of separation between the first adhesive layer and the shell; by setting T2≤104μm, the thickness of the first adhesive layer is not too large, which is conducive to reducing the impact of the arrangement of the first adhesive layer on the thickness of the secondary battery.

[0017] In one or more embodiments of the present application, the first adhesive comprises a substrate layer and an adhesive layer. The material of the substrate layer comprises one of polyethylene terephthalate, co-extruded polypropylene, oriented polystyrene, thermoplastic polyurethane, polylactic acid, polyolefin, and polyimide; the adhesive layer is made of one or a combination of several of 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.

[0018] The second aspect of the present application provides a power consuming device comprising the secondary battery according to any one of the preceding embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structural schematic diagram of a secondary battery in one embodiment of the present application.

[0020] Figure 2 is a cross-sectional structure diagram of a secondary battery in one embodiment of the present application. Figure 1 is a cross-sectional structure diagram at II-II in FIG. 1.

[0021] Figure 3 is a cross-sectional structure diagram of a secondary battery in one embodiment of the present application.

[0022] Figure 4 is a cross-sectional structure diagram of a secondary battery in one embodiment of the present application.

[0023] Figure 5 is a cross-sectional structure diagram of a secondary battery in one embodiment of the present application.

[0024] Figure 6 is a cross-sectional structure diagram of a secondary battery in one embodiment of the present application.

[0025] Figure 7 is a cross-sectional structure diagram of a secondary battery in one embodiment of the present application. Figure 1 is a cross-sectional structure diagram at IV-IV in FIG. 1.

[0026] Figure 8 is a structure diagram of an electrical device in one embodiment of the present application.

[0027] Explanation of main element symbols

[0028] 100, secondary battery; 10, case; 11, sealing portion; 20, electrode assembly; 21, positive electrode sheet; 211, positive electrode current collector; 212, positive electrode active material layer; 22, negative electrode sheet; 221, negative electrode current collector; 222, negative electrode active material layer; 23, separator; 31, first tab bundle; 3101, first tab; 31011, first outer tab; 31012, fourth surface; 311, first portion; 3111, third surface; 312, second portion; 313, third portion; 32, second tab bundle; 3201, second tab; 41, first relay tab; 411, first connecting portion; 4111, first end; 412, second connecting portion; 4121, first surface; 4122, second surface; 42, second relay tab; 51, first adhesive layer; 511, connecting portion; 512, extension portion; 52, second adhesive layer; 53, third adhesive layer; 61, first adhesive member; 62, second adhesive member; 63, third adhesive member; 1000, electrical device; X, first direction.

[0029] The following specific embodiments will further illustrate the present application in conjunction with the above-described drawings. Specific embodiments

[0030] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application.

[0031] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or can exist simultaneously with a middle element. When an element is considered to be "arranged" in another element, it can be directly arranged in the other element or can exist simultaneously with a middle element.

[0032] 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 in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0033] In the description of the embodiments of the present application, the technical terms "first", "second", and the like are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified.

[0034] In the description of the embodiments of the present application, the term "vertical" is used to describe the ideal state between two components. In the actual production or use state, there can be an approximate vertical state between the two components. The two components described as "vertical" can not be an absolute straight line, plane, but can be approximately straight or planar, and the overall extension direction is straight or planar from a macroscopic point of view. The components can be considered as "straight line" or "plane".

[0035] Reference to "an embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily refer to the same embodiment, nor is it necessarily mutually exclusive of other embodiments. The various embodiments of the present application can be combined with each other, provided that there is no conflict.

[0036] A first aspect of embodiments of the present application provides a secondary battery, which comprises a shell, an electrode assembly, a first tab bundle, a first adapter tab and a first adhesive. The shell is a packaging bag, and the electrode assembly is accommodated in the shell. The first tab bundle is accommodated in the shell, and the first tab bundle comprises a plurality of first tabs, each of which is electrically connected to the electrode assembly, and the plurality of first tabs are stacked to form the first tab bundle. The first tab bundle is bent into a U shape, and the first tab bundle comprises a first portion, a second portion and a third portion arranged in sequence, the first portion is connected to the electrode assembly, the second portion connects the first portion and the third portion, and the first tab bundle is located on one side of the electrode assembly along a first direction, and the first direction is perpendicular to the thickness direction of the electrode assembly. The first adapter tab comprises a first connecting portion and a second connecting portion, the first connecting portion comprises a first end, the second connecting portion is connected to the first end, the first connecting portion is connected to the third portion, and the second connecting portion is connected to the first connecting portion, and part of the second connecting portion extends out of the shell; the second connecting portion is located on the same side of the electrode assembly along the thickness direction of the electrode assembly as the second portion; the second connecting portion has a first surface and a second surface oppositely arranged along the thickness direction thereof. The first adhesive layer is arranged on the first surface, and the first adhesive layer comprises a connecting portion and an extending portion connected to each other, the connecting portion adhesively connects the shell and the first adapter tab, the connecting portion and the first adapter tab and the shell form a sealing portion by hot pressing, the extending portion is located in the shell and extends out of the shell along the direction in which the second connecting portion extends out of the shell, the length of the extending portion is L1, the third portion has a third surface facing the third portion along the first direction, and the distance from the sealing portion to the third surface along the first direction is A, and L1≥0.3A; the bending point of the second portion is the highest point of the second portion along the thickness direction of the electrode assembly. The first adhesive adhesively connects the extending portion and the electrode assembly along the direction in which the second connecting portion extends out of the shell, the length of the part of the first adhesive overlapping the extending portion is L2, and 0.5L1≤L2≤L1; the width of the extending portion is W1, the width of the part of the first adhesive overlapping the extending portion is W2, and 0.8W1≤W2≤W1.

[0037] In the secondary battery, the first adhesive adhesively connects the electrode assembly and the first adhesive layer, and the first adhesive layer is adhesively connected to the shell, which is conducive to improving the stability of the position of the electrode assembly relative to the shell, reducing the amplitude of the movement of the electrode assembly relative to the shell when the secondary battery falls, and thus reducing the degree of pulling of the first tab bundle and the possibility of tearing of the first tab bundle. Furthermore, 0.5L1≤L2≤L1 and 0.8W1≤W2≤W1 are provided, which is conducive to improving the stability of the adhesion between the first adhesive and the first adhesive layer and reducing the possibility of the first adhesive being disconnected from the first adhesive layer due to the pulling of the electrode assembly, so as to maintain the connection between the first adhesive layer and the electrode assembly when the secondary battery falls.

[0038] Embodiments of the present application will be further described below with reference to the accompanying drawings.

[0039] As Figure 1 and Figure 2 Embodiments of the present application provide a secondary battery 100 including a housing 10 and an electrode assembly 20, the electrode assembly 20 being housed in the housing 10.

[0040] In some embodiments, the housing 10 is a flexible packaging bag, such as an aluminum plastic film.

[0041] In some embodiments, as shown in Figure 2 The electrode assembly 20 includes a positive electrode sheet 21, a negative electrode sheet 22, and a separator 23 stacked in this order, and the separator 23 is interposed between the positive electrode sheet 21 and the negative electrode sheet 22 to insulate the positive electrode sheet 21 and the negative electrode sheet 22.

[0042] In some embodiments, the positive electrode sheet 21, the separator 23, and the negative electrode sheet 22 are sequentially stacked and then wound to form a wound structure.

[0043] In some embodiments, a plurality of positive electrode sheets 21, a plurality of separators 23, and a plurality of negative electrode sheets 22 are alternately stacked to form a stacked structure.

[0044] In some embodiments, as shown in Figure 2 The positive electrode sheet 21 includes a positive electrode current collector 211 and a positive electrode active material layer 212 stacked in this order.

[0045] In some embodiments, the positive electrode current collector 211 is a metal foil. As an exemplary example, the positive electrode current collector 211 can be a metal foil including at least one of aluminum, nickel, tantalum, titanium, such as an aluminum foil.

[0046] In some embodiments, the positive electrode current collector 211 is a composite current collector.

[0047] In some embodiments, the positive electrode active material layer 212 includes a positive electrode active material. As an exemplary example, the positive electrode active material includes at least one of lithium cobaltate, lithium nickel cobalt manganese acid, lithium nickel cobalt aluminum acid, lithium iron phosphate, lithium manganese iron phosphate, or lithium manganate.

[0048] In some embodiments, as shown in Figure 2 The negative electrode sheet 22 includes a negative electrode current collector 221 and a negative electrode active material layer 222 stacked in this order.

[0049] In some embodiments, the negative electrode current collector 221 is a metal foil. As an exemplary example, the negative electrode current collector 221 can be a metal foil including at least one of copper, nickel, tantalum, titanium, such as a copper foil.

[0050] In some embodiments, the negative electrode current collector 221 is a composite current collector.

[0051] In some embodiments, the negative electrode active material layer 222 includes a negative electrode active material. As an example, the negative electrode active material includes at least one of graphite, hard carbon, soft carbon, silicon, silicon-oxygen materials, and silicon-carbon materials.

[0052] In some embodiments, the separator 23 is one of a polyethylene film, a polypropylene film, a polyester film, or a polyimide film.

[0053] In some embodiments, the secondary battery 100 includes an electrolyte contained in a housing 10.

[0054] In some embodiments, the electrolyte comprises an electrolyte salt. The electrolyte salt comprises at least one of an organic lithium salt or an inorganic lithium salt.

[0055] In some embodiments, the electrolyte salt includes, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium bis(fluoromethanesulfonyl)imide LiN(CF3SO2)2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO2F)2) (LiFSI), lithium hexafluorocesium oxide (LiCsF6), lithium perchlorate (LiClO4), or lithium trifluoromethanesulfonate (LiCF3SO3).

[0056] In some embodiments, such as Figure 2 As shown, the secondary battery 100 also includes a first electrode bundle 31, which is housed in the housing 10. The first electrode bundle 31 includes a plurality of first electrodes 3101, which are electrically connected to the electrode assembly 20. The plurality of first electrodes 3101 are stacked to form the first electrode bundle 31.

[0057] In some embodiments, the first tab 3101 is formed by die-cutting the current collector of the electrode sheet. In the embodiments of this application, to avoid conceptual confusion, the first tab 3101 is considered to be a structure distinct from the current collector after die-cutting.

[0058] In some embodiments, such as Figure 2As shown, the first tab bundle 31 is bent into a U-shape, and the first tab bundle 31 comprises a first portion 311, a second portion 312 and a third portion 313 arranged in sequence, the first portion 311 is connected to the electrode assembly 20, the second portion 312 connects the first portion 311 and the third portion 313, and the first tab bundle 31 is located at one side of the electrode assembly 20 along a first direction X, and the first direction X is perpendicular to the thickness direction of the electrode assembly 20. In this way, it is beneficial to reduce the occupation of the first tab bundle 31 to the head space of the secondary battery 100. It should be noted that the U-shape is a description of the structure of the whole first tab bundle 31, and this shape is formed by the bending of the first tab bundle 31 in the preparation process. Specifically, in the preparation process of the secondary battery 100, a plurality of first tabs 3101 are arranged along the thickness direction of the electrode assembly 20, the plurality of first tabs 3101 are folded along the thickness direction of the electrode assembly 20 by a pressing knife to stack the plurality of first tabs 3101, and then the plurality of first tabs 3101 are connected (for example, welded) and bent to obtain the U-shape structure of the first tab bundle 31.

[0059] In some embodiments, as shown in FIG. 1, the secondary battery 100 comprises a first tab bundle 31, and the first tab bundle 31 comprises a plurality of first tabs 3101, and the plurality of first tabs 3101 are arranged along the thickness direction of the electrode assembly 20. Figure 2 As shown, the secondary battery 100 comprises a first tab bundle 31, and the first tab bundle 31 comprises a plurality of first tabs 3101, and the plurality of first tabs 3101 are arranged along the thickness direction of the electrode assembly 20. Figure 2 The position of the middle line of the electrode assembly 20 is shown by a dotted line.

[0060] In some embodiments, as shown in FIG. 1, the secondary battery 100 comprises a first tab bundle 31, and the first tab bundle 31 comprises a plurality of first tabs 3101, and the plurality of first tabs 3101 are arranged along the thickness direction of the electrode assembly 20. Figure 2 and Figure 3As shown, the secondary battery 100 comprises a first adhesive layer 51, the second connecting portion 412 has a first surface 4121 and a second surface 4122 oppositely arranged along the thickness direction thereof, and the first adhesive layer 51 is arranged on the first surface 4121. The first adhesive layer 51 comprises a connecting portion 511 and an extending portion 512 connected to each other, the connecting portion 511 is bonded to the first adapter tab 41 and the shell 10, the connecting portion 411 and the first adapter tab 41 and the shell 10 form the sealing portion 11 by hot pressing, the extending portion 512 is located in the shell 10 and extends along the direction in which the first adapter tab 41 extends out of the shell 10, the length of the extending portion 512 is L1, the first portion 311 has a third surface 3111 facing the third portion 313 along the first direction X, and the distance between the sealing portion 11 and the third surface 3111 along the first direction X is A, L1≥0.3A; the bending point of the second portion 312 is the highest point of the second portion 312 along the thickness direction of the electrode assembly 20. It should be noted that the connecting portion 511 and the extending portion 512 are different parts of the first adhesive layer 51, and the connecting portion 511 and the extending portion 512 are distinguished according to whether they are connected to the shell 10, and the connecting portion 511 is connected to the shell 10, and the extending portion 512 is not connected to the shell 10.

[0061] In some embodiments, as shown in Figure 2 The secondary battery 100 further comprises a second adhesive layer 52, the second adhesive layer 52 is bonded to the second surface 4122, the second adhesive layer 52 is bonded to the first adhesive layer 51, and the second adhesive layer 52 is bonded to the shell 10.

[0062] In some embodiments, as shown in Figure 2 The second adhesive layer 52 overlaps the connecting portion 511 along the thickness direction of the second connecting portion 412.

[0063] In some embodiments, as shown in Figures 2 to 4 The secondary battery 100 comprises a first adhesive member 61, the first adhesive member 61 is bonded to the extending portion 512 and the electrode assembly 20 along the direction in which the second connecting portion 412 extends out of the shell 10, the length of the portion of the first adhesive member 61 overlapping the extending portion 512 is L2, and 0.5L1≤L2≤L1. The width of the extending portion 512 along the direction perpendicular to the direction in which the second connecting portion 412 extends out of the shell 10 is W1, the width of the portion of the first adhesive member 61 overlapping the extending portion 512 is W2, and 0.8W1≤W2≤W1. Wherein, L1, L2, W1 and W2 can be obtained in the following manner: the first adhesive layer 51 and the first adhesive member 61 are obtained by disassembling the secondary battery 100, and then the laser range finder is used to measure after flattening treatment.

[0064] In the secondary battery 100, the first adhesive 61 is arranged to adhere the electrode assembly 20 and the first adhesive layer 51, and the first adhesive layer 51 is adhered to the case 10, which is advantageous to improve the stability of the position of the electrode assembly 20 relative to the case 10, and to reduce the extent of the movement of the electrode assembly 20 relative to the case 10 when the secondary battery 100 falls, so as to reduce the extent of the pulling of the first tab bundle 31 and the possibility of the tearing of the first tab bundle 31. Furthermore, the arrangement of 0.5L1≤L2≤L1 and 0.8W1≤W2≤W1 is advantageous to improve the stability of the adhesion of the first adhesive 61 and the first adhesive layer 51, and to reduce the possibility of the disconnection of the first adhesive 61 from the first adhesive layer 51 due to the pulling of the electrode assembly 20, so as to maintain the connection of the first adhesive layer 51 and the electrode assembly 20 when the secondary battery 100 falls.

[0065] In some embodiments, the first adhesive 61 comprises a substrate layer and an adhesive layer.

[0066] In some embodiments, the material of the substrate layer comprises one of polyethylene terephthalate, co-extruded polypropylene, oriented polystyrene, thermoplastic polyurethane, polylactic acid, polyolefin, polyimide.

[0067] In some embodiments, the adhesive layer is made of one or a combination of several of 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 alpha-olefin copolymer, petroleum resin, terpene resin, rosin resin.

[0068] In some embodiments, as shown in Figure 2 and Figure 3 , the length of the portion of the first adhesive 61 adhering the electrode assembly 20 along the first direction X is D, and D≥2mm. The arrangement of D≥2mm is advantageous to improve the stability of the adhesion of the first adhesive 61 and the electrode assembly 20, as the portion of the first adhesive 61 adhering the electrode assembly 20 is not too short.

[0069] In some embodiments, as shown in Figure 3 , the length of the electrode assembly 20 along the first direction X is L3, and D≤0.5L3. The arrangement of D≤0.5L3 is advantageous to save material, as the portion of the first adhesive 61 adhering the electrode assembly 20 is not too short.

[0070] In some embodiments, as shown in Figure 2 and Figure 3As shown, the first tab bundle 31 is located on one side of the electrode assembly 20 along the first direction X, which is perpendicular to the thickness direction of the electrode assembly 20. Along the first direction X, the distance from the connecting portion 511 to the electrode assembly 20 is L4, where 1.5mm ≤ L4 ≤ 2mm. Setting L4 ≥ 1.5mm ensures the distance from the connecting portion 511 to the electrode assembly 20 is not too short, allowing space for the extension portion 512 between the connecting portion 511 and the electrode assembly 20; setting L4 ≤ 2mm ensures the distance between the connecting portion 511 and the electrode assembly 20 is not too large, which helps improve the energy density of the secondary battery 100.

[0071] In some embodiments, such as Figure 2 As shown, among the plurality of first tabs 3101, there is a first outer tab 31011. The first outer tab 31011 and the first adhesive layer 51 are located on the same side of the electrode assembly 20 along the thickness direction of the electrode assembly 20. The first outer tab 31011 includes a fourth surface 31012, which is the surface of the first outer tab 31011 along its thickness direction, with a portion of the fourth surface 31012 facing the outside of the electrode assembly 20. The first adhesive member 61 is bonded to the fourth surface 31012 and the extension 512. When the electrode assembly 20 shifts, the first outer tab 31011 experiences greater stress than the other first tabs 3101, making it more prone to tearing. Bonding the first outer tab 31011 with the first adhesive member 61 helps reduce the possibility of tearing the first outer tab 31011; furthermore, the first adhesive member 61 is bonded to the fourth surface 31012, facilitating bonding.

[0072] In some embodiments, L1≤A. Setting L1≤A, along the direction of the second connecting portion 412 extending out of the housing 10, the extension portion 512 of the first adhesive layer 51 does not cross the third surface 3111, which helps to reduce the possibility that the first adhesive layer 51 will squeeze the first electrode bundle 31 when the electrode assembly 20 moves, thereby helping to reduce the possibility that the first electrode bundle 3101 will tear.

[0073] In some embodiments, such as Figure 5 As shown, the extension 512 overlaps with the electrode assembly 20 along its thickness direction. This helps reduce the likelihood of the first adhesive layer 51 compressing the first tab bundle 31 when the electrode assembly 20 shifts, thereby reducing the possibility of the first tab 3101 tearing.

[0074] In some embodiments, such as Figure 3 As shown, the thickness of the first adhesive 61 is T1, and 11.2μm≤T1. Setting the thickness of the first adhesive 61 to T1≥11.2μm ensures that the thickness of the first adhesive 61 is not too thin, which helps to reduce the possibility of the first adhesive 61 breaking due to being pulled by the electrode assembly 20.

[0075] In some embodiments, T1≤20.8 μm. By setting T1≤20.8 μm, the thickness of the first adhesive 61 is not too thick, which is conducive to reducing the impact of the first adhesive 61 on the thickness of the secondary battery 100.

[0076] In some embodiments, as shown in FIG. 4, the second adhesive 62 is arranged on the first portion 311 and the third portion 313, and the second adhesive 62 is arranged between the first portion 311 and the third portion 313. Figure 6 In some embodiments, as shown in FIG. 4, the second adhesive 62 is arranged on the first portion 311 and the third portion 313, and the second adhesive 62 is arranged between the first portion 311 and the third portion 313.

[0077] In some embodiments, as shown in FIG. 4, the second adhesive 62 is arranged on the first portion 311 and the third portion 313, and the second adhesive 62 is arranged between the first portion 311 and the third portion 313. Figure 2 In some embodiments, as shown in FIG. 4, the second adhesive 62 is arranged on the first portion 311 and the third portion 313, and the second adhesive 62 is arranged between the first portion 311 and the third portion 313.

[0078] In some embodiments, as shown in FIG. 4, the second adhesive 62 is arranged on the first portion 311 and the third portion 313, and the second adhesive 62 is arranged between the first portion 311 and the third portion 313. Figure 2 In some embodiments, as shown in FIG. 4, the second adhesive 62 is arranged on the first portion 311 and the third portion 313, and the second adhesive 62 is arranged between the first portion 311 and the third portion 313.

[0079] In some embodiments, as shown in FIG. 4, the second adhesive 62 is arranged on the first portion 311 and the third portion 313, and the second adhesive 62 is arranged between the first portion 311 and the third portion 313. Figure 7 In some embodiments, as shown in FIG. 4, the second adhesive 62 is arranged on the first portion 311 and the third portion 313, and the second adhesive 62 is arranged between the first portion 311 and the third portion 313.

[0080] In some embodiments, as shown in FIG. 4, the second adhesive 62 is arranged on the first portion 311 and the third portion 313, and the second adhesive 62 is arranged between the first portion 311 and the third portion 313. Figure 7 In some embodiments, as shown in FIG. 4, the second adhesive 62 is arranged on the first portion 311 and the third portion 313, and the second adhesive 62 is arranged between the first portion 311 and the third portion 313. In some embodiments, as shown in FIG. 4, the second adhesive 62 is arranged on the first portion 311 and the third portion 313, and the second adhesive 62 is arranged between the first portion 311 and the third portion 313.

[0081] In some embodiments, as shown in Figure 7 The secondary battery 100 includes a third adhesive layer 53 and a third adhesive member 63, which adheres the third adhesive layer 53 and the electrode assembly 20. The specific arrangement of the third adhesive layer 53 and the third adhesive member 63 can refer to the arrangement of the first adhesive layer 51 and the first adhesive member 61, which will not be repeated here.

[0082] As shown in Figure 8 The secondary battery 100 includes a third adhesive layer 53 and a third adhesive member 63, which adheres the third adhesive layer 53 and the electrode assembly 20. The specific arrangement of the third adhesive layer 53 and the third adhesive member 63 can refer to the arrangement of the first adhesive layer 51 and the first adhesive member 61, which will not be repeated here.

[0083] To verify the effect of the scheme in the embodiments of the present application, the inventors conducted the following experiments. The experiment includes 13 experimental groups, specifically 4 groups of comparative examples and 9 groups of embodiments, and each experimental group includes 100 secondary batteries 100.

[0084] The preparation process of the secondary battery 100 in Example 1 includes the following steps:

[0085] (1) Preparation of the positive electrode sheet 21: Mix active material lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), CNT (carbon nanotube), and polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:0.5:0.5:1.5, add N-methyl pyrrolidone (NMP) as a solvent, and adjust to a solid content of 75wt% of the positive electrode active material, and stir uniformly for standby. Use an aluminum foil with a thickness of 10μm as the positive electrode current collector 211. Use a slot coater to uniformly coat the above-mentioned active material on one side of the positive electrode current collector 211, and then dry at 90℃ to obtain a positive electrode sheet 21 with a single side coated with positive electrode active material. At this time, the thickness of the positive electrode active material layer 212 is 50μm. Then repeat the above coating step on the other side of the positive electrode current collector 211. Then cold-press the coated positive electrode sheet 21, and after cold-pressing, the thickness of the positive electrode active material layer 212 is 35μm. The area of the positive electrode current collector 211 not covered by the positive electrode active material layer 212 is the positive electrode empty foil area, and the positive electrode empty foil area is die-cut to obtain a plurality of positive electrode tabs.

[0086] (2) Preparation of the negative electrode sheet 22: The active material artificial graphite, conductive carbon black (Super P), butadiene rubber (SBR), and CMC (sodium carboxymethyl cellulose) were mixed in a weight ratio of 97:0.5:1.3:1.2, and deionized water was added as a solvent to prepare a negative electrode active material with a weight percentage of 50 wt%, which was then stirred uniformly for use. A copper foil with a thickness of 10 μm was used as the negative current collector 221. The negative electrode active material was uniformly coated on one side of the negative current collector 221 using a slot coater, and then dried at 110°C to obtain a negative electrode sheet 22 with a negative electrode active material layer 222 coated on one side. At this time, the thickness of the negative electrode active material layer 222 was 55 μm. The above steps were repeated on the other side of the negative current collector 221 to obtain a negative electrode sheet 22 with a negative electrode active material layer 222 coated on both sides. The coated negative electrode sheet 22 was then cold-pressed, and the thickness of the negative electrode active material layer 222 after cold-pressing was 45 μm. The area of the negative current collector 221 not covered by the negative electrode active material layer 222 was a negative empty foil area, and the negative empty foil area was die-cut to obtain a plurality of negative tabs.

[0087] (3) Preparation of the electrolyte: In a dry argon atmosphere, first, ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a mass ratio of EC: EMC: DEC = 30:50:20 to form a base organic solvent, and then lithium salt lithium hexafluorophosphate (LiPF6) was added to the base organic solvent to dissolve and mix uniformly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0088] (4) Preparation of the separator film 23: A 7 μm thick polyethylene porous polymer film was used as the separator film 23.

[0089] (5) Preparation of the electrode assembly 20: The positive electrode sheet 21, the separator film 23, and the negative electrode sheet 22 were stacked and wound. A plurality of positive electrode sheets 21 were stacked in the thickness direction of the electrode assembly 20 to form a positive tab bundle (in this embodiment, the positive tab bundle is the first tab bundle 31), and a plurality of negative electrode sheets 22 were stacked in the thickness direction of the electrode assembly 20 to form a negative tab bundle (equivalent to the second tab bundle 32). The positive tab adapter (equivalent to the first tab adapter 41) was welded to the positive tab bundle, and the negative tab adapter (equivalent to the second tab adapter 42) was welded to the negative tab bundle. During the welding process, the positive tab bundle and the negative tab bundle were both bent into a U shape. The positive tab adapter was bonded with the first adhesive layer 51 and the second adhesive layer 52, and the first bonding member 61 was used to bond the first adhesive layer 51 and the electrode assembly 20.

[0090] (6) Assembly of the secondary battery 100: Place the punched aluminum plastic film into the assembly fixture with the pit surface facing up, place the electrode assembly 20 into the pit, and apply an external force to compress it. Then place another punched aluminum plastic film with the pit surface facing down on the electrode assembly 20, and heat seal the three edges of the two aluminum plastic films using hot pressing, with the unsealed edge being the side where the positive and negative switching tabs extend out of the shell 10. Then inject electrolyte through the unsealed edge, and then seal the two aluminum plastic films with the first and second adhesive layers 51 and 52, with the portion of the first adhesive layer 51 connecting to the aluminum plastic film forming a connecting portion 511 and the portion inside the aluminum plastic film package being an extension portion 512. Then, through processes such as standing, hot pressing, and shaping, the secondary battery 100 is obtained.

[0091] (7) In the prepared secondary battery 100, A = 2 mm, W1 = 6 mm, and the distance from the connecting portion 511 to the electrode assembly 20 is 4.2 mm in the direction in which the second connecting portion 412 extends out of the shell 10. The data related to the experiment of the secondary battery 100 in Example 1 are recorded in Table 1.

[0092] The preparation process of the secondary battery 100 in Comparative Example 1 is basically the same as that in Example 1, with the difference being that the secondary battery 100 in Comparative Example 1 does not have the first adhesive member 61.

[0093] The preparation processes of the secondary batteries 100 in Comparative Examples 2 and 3 and Examples 2 to 9 are basically the same as that in Example 1, with the difference being that some parameters are different, and the related parameters are recorded in Table 1. It should be noted that in Example 9, L1 > 4.2 mm, and the first adhesive layer 51 overlaps the electrode assembly 20 in the thickness direction of the electrode assembly 20.

[0094] After the preparation of the secondary batteries 100 in the experimental groups is completed, drop test is performed on the secondary batteries 100 in each experimental group, and the process of the drop test is as follows:

[0095] The secondary battery 100 is fixed in the drop test fixture using double-sided tape, and the six sides of the fixture are sequentially numbered 1, 2, 3, 4, 5, and 6, and the four corners of the fixture are sequentially numbered C1, C2, C3, and C4.

[0096] At 25°C, the fixture is placed on a test table 1.5 m high, and the secondary batteries 100 are sequentially dropped according to the order of numbers 1 to 6, and then sequentially dropped according to the order of numbers C1 to C4. After the drop test is completed, the lithium ion secondary batteries 100 are left to stand for 1 h, and then the positive and negative tab bundles are observed for cracks using SEM. The secondary batteries 100 in which the positive and negative tab bundles do not have cracks are considered to have passed the drop test. The number of secondary batteries 100 that pass the drop test in each experimental group is counted, and the experimental results are recorded in Table 1.

[0097] Table 1

[0098]

[0099] Note: In Table 1, " / " means no data.

[0100] From Table 1, it can be seen that the secondary battery 100 in Examples 1 to 6 has a higher pass rate in the drop experiment than Comparative Examples 1 to 4, because, compared with Comparative Example 1, the secondary battery 100 in Examples 1 to 6 is provided with the first adhesive member 61, which is conducive to reducing the amplitude of the electrode assembly 20 relative to the shell 10, thereby reducing the possibility of tearing of the positive and negative tab bundles; compared with Comparative Example 2, the secondary battery 100 in Examples 1 to 6 satisfies L1≥0.3A, and the length of the first adhesive layer 51 available for the first adhesive member 61 to adhere to is longer, so that the first adhesive member 61 is less likely to be disconnected from the first adhesive layer 51 when the secondary battery 100 drops, thereby being more likely to function; compared with Comparative Examples 3 and 4, the secondary battery 100 in Examples 1 to 6 satisfies 0.5L1≤L2≤L1 and W2≥0.5W1, and the adhesion of the first adhesive member 61 to the first adhesive layer 51 is more stable, so that the first adhesive member 61 is less likely to be disconnected from the first adhesive layer 51 when the secondary battery 100 drops, thereby being more likely to function. It can be seen that setting L1≥0.3A, 0.5L1≤L2≤L1 and W2≥0.5W1 is conducive to improving the stability of the adhesion of the first adhesive member 61 to the first adhesive layer 51 and reducing the possibility of the first adhesive member 61 being disconnected from the first adhesive layer 51 due to being pulled by the electrode assembly 20, so as to maintain the state of the first adhesive layer 51 being connected to the electrode assembly 20 when the secondary battery 100 drops, and the first adhesive member 61 can reduce the amplitude of the electrode assembly 20 relative to the shell 10, thereby reducing the possibility of tearing of the positive and negative tab bundles.

[0101] In Examples 2 and 3, the secondary battery 100 satisfies D≥2mm, and the pass rate of the secondary battery 100 in Examples 2 and 3 in the drop experiment is higher than that in Example 1, because the length of the first adhesive member 61 adhered to the electrode assembly 20 in Examples 2 and 3 is longer, and the adhesion of the first adhesive member 61 to the electrode assembly 20 is more stable, so that the first adhesive member 61 is less likely to be disconnected from the electrode assembly 20 when the secondary battery 100 drops, thereby being more likely to function. It can be seen that setting D≥2mm is conducive to improving the stability of the adhesion of the first adhesive member 61 to the electrode assembly 20, because the part of the first adhesive member 61 adhered to the electrode assembly 20 is not too short.

[0102] In Embodiment 3, Embodiment 5 and Embodiment 6, the secondary battery 100 satisfies T1≥11.2μm, and the secondary battery 100 in Embodiment 3, Embodiment 5 and Embodiment 6 has a higher pass rate in the drop test than that in Embodiment 4. It can be seen that the thickness T1 of the first adhesive 61 is set to be≥11.2μm, and the thickness of the first adhesive 61 is not too thin, which is conducive to reducing the possibility of the first adhesive 61 being broken by the pulling of the electrode assembly 20. On this basis, T1≤20.8μm is set, and the thickness of the first adhesive 61 is not too thick, which is conducive to reducing the influence of the first adhesive 61 on the thickness of the secondary battery 100.

[0103] In Embodiment 3 and Embodiment 7, the secondary battery 100 satisfies L1≤A, and the secondary battery 100 in Embodiment 3 and Embodiment 7 has a higher pass rate in the drop test than that in Embodiment 8. It can be seen that L1≤A is set, and the extension 512 of the first adhesive layer 51 does not cross the third surface 3111 in the direction in which the second connecting portion 412 extends out of the shell 10, which is conducive to reducing the possibility of the first adhesive layer 51 extruding the first tab bundle 31 when the electrode assembly 20 moves, thereby being conducive to reducing the possibility of the first tab 3101 being torn.

[0104] In Embodiment 9, the secondary battery 100 satisfies that the extension 512 extends along the second connecting portion 412 in the direction in which the shell 10 extends and beyond the third surface 3111, and the secondary battery 100 in Embodiment 9 has a higher pass rate in the drop test than that in Embodiment 8. It can be seen that the extension 512 is stacked with the electrode assembly 20, which is conducive to reducing the possibility of the first adhesive layer 51 extruding the first tab bundle 31 when the electrode assembly 20 moves, thereby being conducive to reducing the possibility of the first tab 3101 being torn.

[0105] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application, and are not used as a limitation to the present application, and as long as the above embodiments are within the spirit and scope of the present application, any suitable changes and variations of the above embodiments are within the disclosure range of the present application.

Claims

1. A secondary battery, characterized in that, include: The casing, which is a packaging bag; The electrode assembly is housed within the housing; A first electrode bundle is housed within the housing. The first electrode bundle includes multiple first electrodes, each of which is electrically connected to the electrode assembly. The multiple first electrodes are stacked to form the first electrode bundle. The first electrode bundle is bent into a U-shape and includes a first portion, a second portion, and a third portion arranged sequentially. The first portion is connected to the electrode assembly, and the second portion is connected to the first portion and the third portion. The first electrode bundle is located on one side of the electrode assembly along a first direction, which is perpendicular to the thickness direction of the electrode assembly. A first adapter tab includes a first connecting portion and a second connecting portion. The first connecting portion includes a first end, and the second connecting portion is connected to the first end. The first connecting portion is connected to the third part, and a portion of the second connecting portion extends out of the housing. The second connecting portion and the second part are located on the same side of the electrode assembly along the thickness direction of the electrode assembly. The second connecting portion has a first surface and a second surface that are disposed opposite to each other along its thickness direction. A first adhesive layer is disposed on the first surface. The first adhesive layer includes a connecting portion and an extension portion that are connected to each other. The connecting portion adheres to the housing and the first adapter tab and forms a sealing portion. The extension portion is located inside the housing and extends out of the housing along the direction of the second connecting portion. The length of the extension portion is L1. The first portion has a third surface. The third surface faces the third portion along the first direction. Along the first direction, the distance from the sealing portion to the third surface is A, and L1≥0.3A. A first adhesive element bonds the extension portion and the electrode assembly. Extending from the housing along the direction of the second connecting portion, the length of the portion overlapping the extension portion is L2, where 0.5L1≤L2≤L1. Along the direction perpendicular to the second connecting portion extending from the housing, the width of the extension portion is W1, and the width of the portion overlapping the extension portion is W2, where 0.8W1≤W2≤W1.

2. The secondary battery as described in claim 1, characterized in that, The length of the portion of the first adhesive that bonds to the electrode assembly along the first direction is D, where D ≥ 2 mm.

3. The secondary battery as described in claim 2, characterized in that, The length of the electrode assembly along the first direction is L3, and D≤0.5L3.

4. The secondary battery as described in claim 1, characterized in that, Along the first direction, the distance from the connecting part to the electrode assembly is L4, where 1.5mm≤L4≤2mm.

5. The secondary battery as described in any one of claims 1-4, characterized in that, The plurality of first tabs includes a first outer tab, and the first outer tab and the first adhesive layer are located on the same side of the electrode assembly along the thickness direction of the electrode assembly. The first outer tab includes a fourth surface, which is the surface of the first outer tab along its thickness direction; the first adhesive is bonded to the fourth surface and the extension.

6. The secondary battery as described in claim 5, characterized in that, L1≤A.

7. The secondary battery as described in claim 5, characterized in that, Along the thickness direction of the electrode assembly, the extension overlaps with the electrode assembly.

8. The secondary battery as described in claim 5, characterized in that, The thickness of the first adhesive component is T1, and 11.2 μm ≤ T1.

9. The secondary battery as described in claim 8, characterized in that, T1≤20.8μm.

10. The secondary battery as described in claim 1, characterized in that, The secondary battery includes a second adhesive layer, a portion of which is disposed on the second surface and connects the housing and the second connecting portion. Along the first direction, a portion of the second adhesive layer is located between the housing and the first connecting portion.

11. The secondary battery as described in claim 1, characterized in that, The first connecting portion is welded to the third portion, forming a solder mark; The secondary battery further includes a second adhesive member, which is bonded to the first portion and extends out of the housing along the direction of the second connection portion. At least a portion of the second adhesive member is located between the first portion and the third portion, and in the thickness direction of the third portion, the second adhesive member covers the solder mark.

12. The secondary battery as described in claim 1, characterized in that, The thickness of the first adhesive layer is T2, 56μm≤T2≤104μm.

13. The secondary battery as described in claim 1, characterized in that, The first adhesive component includes a substrate layer and an adhesive layer; The material of the substrate layer includes one of polyethylene terephthalate, co-extruded polypropylene, oriented polystyrene, thermoplastic polyurethane, polylactic acid, polyolefin, and polyimide. The adhesive layer 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.

14. An electrical appliance, characterized in that, Includes the secondary battery as described in any one of claims 1 to 13.

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