Secondary battery, electric device, and method for manufacturing secondary battery

Abstract

Embodiments of the present application provide a secondary battery, an electric device, and a method for manufacturing a secondary battery. The secondary battery includes an electrode assembly, the electrode assembly including a first electrode tab at an outermost layer thereof, the first electrode tab including a first current collector, a first active material layer, and a first insulating layer, the first current collector having a first surface and a second surface disposed opposite to each other, the first active material layer being disposed on the first surface, and the first insulating layer being disposed on the second surface. The secondary battery further includes a first adhesive member, the first adhesive member including a first portion and a second portion, the first portion being adhered to a surface of a portion of the second surface that is not covered by the first insulating layer, or the first portion being adhered to a region of the first insulating layer that is thinned after a portion of material of the first insulating layer is removed, and the second portion being adhered to a surface of the electrode assembly on a side in a second direction. In the secondary battery, the degree and the possibility of curling of the outermost layer electrode tab of the electrode assembly can be reduced, and the energy density of the secondary battery can be improved.

Description

TECHNICAL FIELD

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

[0002] The outermost electrode sheet of the laminated secondary battery is usually coated with an active material layer only on one side of the current collector facing the middle of the electrode assembly, so as to improve the energy density of the secondary battery and reduce the cost. However, the electrode sheet coated with the active material layer on one side is prone to curling after cold pressing, because the active material particles are embedded into the surface of the current collector, which causes a transverse stress between the active material layer and the current collector. After die cutting, the electrode sheet is prone to curling, which leads to a low yield or even cannot be processed in subsequent processes. The transverse stress may also cause the electrode sheet to be lifted and separated from the separator, and further cause lithium precipitation.

[0003] In order to improve the curling resistance of the electrode sheet, the prior art provides a scheme of increasing the thickness of the current collector. However, this scheme increases the thickness of the electrode assembly, which causes a loss of the energy density of the secondary battery. SUMMARY

[0004] In view of the above problems, a scheme of arranging a coating layer on the surface of the current collector which is not coated with the active material layer is developed. Compared with the scheme of increasing the thickness of the current collector, the electrode sheet prepared by this scheme has a thinner thickness, and the energy density of the secondary battery can be improved.

[0005] In the research process of the present application, the inventors found that the laminated electrode assembly often needs to be wrapped with adhesive paper on the two end surfaces and the side surface along the thickness direction of the electrode assembly, so as to maintain the structure of the electrode assembly. However, the adhesive paper and the coating layer are stacked, which is not conducive to improving the energy density of the secondary battery.

[0006] In view of the above problems, the embodiments of the present application provide a first secondary battery, an electric device, and a preparation method of the secondary battery, which can reduce the degree and possibility of curling of the outermost electrode sheet of the electrode assembly, and improve the energy density of the secondary battery.

[0007] A first aspect of embodiments of the present application provides a secondary battery, the secondary battery comprising an electrode assembly, the electrode assembly being of a stacked structure, the electrode assembly comprising a first electrode tab located at an outermost layer of the electrode assembly, the first electrode tab comprising a first current collector and a first active material layer, the first current collector having a first surface and a second surface oppositely arranged along a first direction, the first surface facing an inner side of the electrode assembly, the first active material layer being provided on the first surface; the first electrode tab further comprising a first insulating layer, the first insulating layer being provided on the second surface, the first insulating layer being configured to resist a curling tendency of the first current collector, the first direction being a thickness direction of the first electrode tab. The secondary battery further comprises a first adhesive member, the first adhesive member comprising a first portion and a second portion of an integral structure, the first portion being adhered to a surface of the electrode assembly on a same side as the first insulating layer; the second portion being adhered to a surface of the electrode assembly on a side of a second direction, the second direction being perpendicular to the first direction.

[0008] In the secondary battery, by providing the first insulating layer, it is beneficial to reduce the degree and possibility of curling of the first electrode tab due to the first active material layer being coated on only a single surface of the first current collector. In this way, it is beneficial to improve the production yield of the processing procedure after cold pressing in the production process of the secondary battery; it is beneficial to reduce the possibility of separation of the first electrode tab from the separator in the use process of the secondary battery. The first adhesive member is capable of providing a binding force to the electrode tab in the electrode assembly to maintain the stacked state of the electrode tab and the separator in the electrode assembly.

[0009] In an optional embodiment of the present application, the first insulating layer is provided on a portion of the surface of the second surface, and the first portion is adhered to a portion of the surface of the second surface which is not covered by the first insulating layer. In this way, the first insulating layer and the first adhesive member do not overlap in the first direction, which is beneficial to reduce the impact of the provision of the first insulating layer on the thickness of the secondary battery, so as to improve the energy density of the secondary battery.

[0010] In an optional embodiment of the present application, the thickness of the first insulating layer along the first direction is T1, and 10 μm ≤ T1 ≤ 20 μm. By setting T1 ≥ 10 μm, the thickness of the first insulating layer is not too small, which is beneficial to improve the effect of the first insulating layer in resisting the curling tendency of the first electrode tab; by setting T1 ≤ 20 μm, the thickness of the first insulating layer is not too thick, which is beneficial to reduce the impact of the provision of the first insulating layer on the thickness of the electrode assembly.

[0011] In an optional embodiment of the present application, the first insulating layer is arranged on at least part of the surface of the second surface, the first insulating layer comprises a main body portion and a thinned portion in an integral structure, the thickness of the main body portion along the first direction is greater than the thickness of the thinned portion along the first direction; the first portion is bonded to the surface of the thinned portion facing away from the first current collector along the first direction. The first portion is arranged on the thinned portion, which is conducive to reducing the influence of the thickness of the first bonding member and the first insulating layer on the thickness of the secondary battery; and the arrangement of the thinned portion can reduce the degree and possibility of curling of the first tab at the position where the first portion is bonded.

[0012] In an optional embodiment of the present application, the thickness of the first portion along the first direction is T2, the thickness of the main body portion along the first direction is T2, and 10 μm≤T2≤20 μm. By setting T2≥10 μm, the thickness of the main body portion is not too small, which is conducive to improving the ability of the main body portion to resist curling of the first tab; by setting T2≤20 μm, the thickness of the main body portion is not too large, which is conducive to reducing the influence of the main body portion on the thickness of the electrode assembly.

[0013] In an optional embodiment of the present application, the thickness of the thinned portion along the first direction is T3, and 2 μm≤T3≤4 μm. By setting T3≥2 μm, the thickness of the thinned portion is not too small, which is conducive to improving the ability of the thinned portion to resist curling of the first tab; by setting T3≤4 μm, the thickness of the thinned portion is not too large, which is conducive to reducing the influence of the sum of the thicknesses of the thinned portion and the first portion on the thickness of the secondary battery.

[0014] In an optional embodiment of the present application, the distance between the main body portion and the first portion along the second direction is W1, and 0 mm≤W1≤2 mm. By setting W1≤2 mm, the distance between the first portion and the main body portion is not too large, which is conducive to improving the area of the projection of the main body portion along the first direction, thereby reducing the degree and possibility of curling of the first tab.

[0015] In an optional embodiment of the present application, the first insulating layer is arranged on at least part of the surface of the second surface, the thickness of the first insulating layer along the first direction is T4, and 2 μm≤T4≤4 μm. The thickness of the first insulating layer is obtained after part of the material of the first insulating layer is removed after coating is completed. The first portion is bonded to the surface of the first insulating layer facing away from the first current collector along the first direction. The first insulating layer is thinned before the first bonding member is bonded, which is conducive to reducing the influence of the sum of the thicknesses of the first portion and the first insulating layer along the first direction on the energy density of the secondary battery; in addition, by setting T4≥2 μm, the thickness of the first insulating layer is not too small, which is conducive to improving the ability of the first insulating layer to resist curling of the first tab; by setting T4≤4 μm, the thickness of the first insulating layer is not too large, which is conducive to reducing the influence of the sum of the thicknesses of the first insulating layer and the first portion on the thickness of the secondary battery.

[0016] In an optional embodiment of the present application, the thickness of the first portion along the first direction is T5, 8 μm≤T5≤12 μm. T5≥8 μm is set to prevent the thickness of the first portion from being too small, which is conducive to reducing the difficulty of producing the first portion and improving the strength of the first portion to reduce the possibility of the first portion being broken due to stress in the first tab 30; T5≤12 μm is set to prevent the thickness of the first portion from being too large, which is conducive to reducing the influence of the thickness of the first portion on the thickness of the electrode assembly.

[0017] In an optional embodiment of the present application, the second face is polygonal, and the first insulating layer contacts any vertex of the second face. The influence area of the first insulating layer against the effect of curling of the first tab involves any corner position of the first tab, which is conducive to reducing the possibility of the first tab being curled.

[0018] In an optional embodiment of the present application, the second face is polygonal, and the first insulating layer contacts any vertex of the second face and any edge of the second face. The influence area of the first insulating layer against the effect of curling of the first tab involves any corner position and any edge of the first tab, which is conducive to further reducing the possibility of the first tab being curled.

[0019] In an optional embodiment of the present application, the material of the first insulating layer comprises a main material and a binder. The main material comprises at least one of alumina, boehmite, zirconia or titania, and the mass percentage of the main material is 80% to 99% based on the mass of the first insulating layer; the binder comprises at least one of styrene-butadiene rubber, polyvinylidene fluoride or polyacrylate, and the mass percentage of the binder is 0.3% to 20% based on the mass of the first insulating layer.

[0020] In an optional embodiment of the present application, the thickness of the first current collector along the first direction is T6, 8 μm≤T6≤12 μm. T6≥8 μm is set to prevent the thickness of the first current collector from being too thin, which is conducive to reducing the difficulty of preparing the first current collector, improving the current-carrying capacity and mechanical strength of the first current collector, and reducing the possibility of the first tab being curled; T6≤12 μm is set to prevent the thickness of the first current collector from being too thick, which is conducive to improving the energy density of the secondary battery.

[0021] In an optional embodiment of the present application, the width of the first portion along the second direction is W2, 4 mm≤W2≤12 mm. W2≥4 mm is set to prevent the width of the first portion along the second direction Y from being too small, which is conducive to improving the binding capacity of the first adhesive to the electrode assembly to maintain the structure of the electrode assembly; W2≤12 mm is set to prevent the width of the first adhesive along the second direction from being too large, which is conducive to saving materials.

[0022] A second aspect of embodiments of the present application provides a power consuming device including the secondary battery according to any one of the preceding embodiments.

[0023] A third aspect of embodiments of the present application provides a method of manufacturing a secondary battery, the method including the steps of:

[0024] A first electrode sheet is taken, the first electrode sheet including a first current collector and a first active material layer, the first current collector having a first surface and a second surface disposed opposite to each other in a first direction, the first active material layer being provided on the first surface, the first direction being a thickness direction of the first electrode sheet;

[0025] A first insulating layer is provided on the second surface, the first insulating layer covering part of the surface of the second surface;

[0026] The first electrode sheet is provided on an outermost layer of the electrode assembly;

[0027] A first adhesive member is taken, and the first adhesive member is adhered to part of the surface of the second surface not covered by the first insulating layer and a surface of the electrode assembly on a second direction side, the second direction being perpendicular to the first direction.

[0028] In an optional embodiment of the present application, the method of manufacturing a secondary battery includes the steps of:

[0029] Before the first insulating layer is provided on the second surface, a gummed paper is adhered to part of the surface of the second surface;

[0030] After the first insulating layer is provided on the second surface, part of the first insulating layer is covered by the gummed paper;

[0031] After the first electrode sheet is provided on the outermost layer of the electrode assembly, the gummed paper is removed so that part of the surface of the second surface is exposed from the first insulating layer.

[0032] A fourth aspect of embodiments of the present application provides another method of manufacturing a secondary battery, the method including the steps of:

[0033] A first electrode sheet is taken, the first electrode sheet including a first current collector and a first active material layer, the first current collector having a first surface and a second surface disposed opposite to each other in a first direction, the first active material layer being provided on the first surface, the first direction being a thickness direction of the first electrode sheet;

[0034] A first insulating layer is provided on the second surface, the first insulating layer covering part of the surface of the second surface;

[0035] The first electrode sheet is provided on an outermost layer of the electrode assembly;

[0036] Part of the material of the first insulating layer is removed so that a thickness of at least part of the first insulating layer in the first direction is thinned;

[0037] A first adhesive member is taken, and a portion of the first adhesive member is adhered to a surface of the first insulating layer thickness reduction region facing away from the first current collector in the first direction, and a portion of the first adhesive member is adhered to a surface of the electrode assembly on the second direction side.

[0038] In one embodiment of the present application, the material of the portion of the first insulating layer is removed using a laser. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is a schematic diagram of the structure of a secondary battery in one embodiment of the present application.

[0040] Figure 2 is a schematic diagram of the structure of a secondary battery in one embodiment of the present application. Figure 1 is a schematic diagram of the cross-sectional structure at II-II in

[0041] Figure 3 is a schematic diagram of the structure of an electrode assembly and a first adhesive member in one embodiment of the present application.

[0042] Figure 4 is a schematic diagram of the structure of a secondary battery in one embodiment of the present application. Figure 3 is a schematic diagram of the cross-sectional structure at IV-IV in

[0043] Figure 5 is a schematic diagram of the structure of an electrode assembly and a first adhesive member in one embodiment of the present application.

[0044] Figure 6 is a schematic diagram of the structure of a secondary battery in one embodiment of the present application. Figure 5 is a schematic diagram of the cross-sectional structure at VI-VI in

[0045] Figure 7 is a schematic diagram of the structure of an electrode assembly and a first adhesive member in one embodiment of the present application.

[0046] Figure 8 is a schematic diagram of the structure of a secondary battery in one embodiment of the present application. Figure 7 is a schematic diagram of the cross-sectional structure at VIII-VIII in

[0047] Figure 9 is a schematic diagram of the structure of a secondary battery in one embodiment of the present application.

[0048] MAIN ELEMENT SYMBOL EXPLANATION

[0049] 1000, secondary battery; 100, electrode assembly; 10, positive electrode sheet; 11, positive electrode current collector; 12, positive electrode active material layer; 20, negative electrode sheet; 21, negative electrode current collector; 22, negative electrode active material layer; 30, first electrode sheet; 31, first current collector; 311, first surface; 312, second surface; 32, first active material layer; 33, first insulating layer; 331, main body portion; 332, thinned portion; 40, separator; 50, positive electrode tab; 60, negative electrode tab; 200, case; 300, first adhesive member; 310, first portion; 320, second portion; 330, third portion; 10000, electric device; X, first direction; Y, second direction. DETAILED DESCRIPTION

[0050] 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 a part of the embodiments of the present application, not all the embodiments of the present application.

[0051] 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 "provided" on another element, it can be directly provided on the other element or can exist simultaneously with a middle element.

[0052] 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.

[0053] 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.

[0054] 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".

[0055] The term "parallel" is used to describe an ideal state between two components. In a state of actual production or use, there can be a state close to parallel between the two components. The two components described as "parallel" can not be an absolute straight line, plane, or can be approximately straight or planar, and as a whole, the overall extension direction is straight or planar, which can be considered as "straight line" or "plane".

[0056] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive or alternative embodiments. Various features that are described in the specification can be combined together in any combination.

[0057] Embodiments of the application will be further described below with reference to the drawings.

[0058] As shown in Figure 1 and Figure 2 Embodiments of the application provide a secondary battery 1000, which includes a housing 200 and an electrode assembly 100 housed in the housing 200.

[0059] In some embodiments, the housing 200 is a flexible packaging bag, such as an aluminum plastic film. In other embodiments, the housing 200 is a hard shell, such as a plastic shell, or a metal shell including at least one of a steel alloy, an aluminum alloy, and a copper alloy.

[0060] In some embodiments, as shown in Figure 2 The electrode assembly 100 includes a plurality of positive electrode sheets 10, a plurality of separator films 40, and a plurality of negative electrode sheets 20, which are alternately stacked in a first direction X to form a stacked structure, and for any adjacent positive electrode sheet 10 and negative electrode sheet 20, there is a separator film 40 disposed therebetween. The first direction X is the thickness direction of the positive electrode sheet 10.

[0061] In some embodiments, as shown in Figure 2 The positive electrode sheet 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12. For the positive electrode sheet 10 located in the non-outermost layer of the electrode assembly 100, two positive electrode active material layers 12 are respectively disposed on both surfaces of the positive electrode current collector 11 along the first direction X.

[0062] In some embodiments, as shown in Figure 2 The negative electrode sheet 20 includes a negative electrode current collector 21 and a negative electrode active material layer 22. For the negative electrode sheet 20 located in the non-outermost layer of the electrode assembly 100, two negative electrode active material layers 22 are respectively disposed on both surfaces of the negative electrode current collector 21 along the first direction X.

[0063] In some embodiments, as shown in Figure 2 and Figure 4 the outermost layer of the electrode assembly 100 is defined as a first electrode tab 30. The first electrode tab 30 includes a first current collector 31 having a first surface 311 and a second surface 312 oppositely arranged along a first direction X, the first surface 311 facing an inner side of the electrode assembly 100, and a first active material layer 32 disposed on the first surface 311. When the first electrode tab 30 is a positive electrode tab 10, the first current collector 31 is a positive current collector 11 and the first active material layer 32 is a positive active material layer 12. When the first electrode tab 30 is a negative electrode tab 20, the first current collector 31 is a negative current collector 21 and the first active material layer 32 is a negative active material layer 22.

[0064] In some embodiments, the positive current collector 11 and the negative current collector 21 are both metal layers. As an exemplary example, the positive current collector 11 can be a metal layer including at least one of aluminum, nickel, tantalum, titanium, such as an aluminum foil. The negative current collector 21 can be a metal layer including at least one of copper, nickel, tantalum, titanium, such as a copper foil.

[0065] In some embodiments, the positive active material includes at least one of lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium iron phosphate, lithium manganese iron phosphate, or lithium manganate.

[0066] In some embodiments, the negative active material includes at least one of graphite, hard carbon, soft carbon, silicon, silicon-oxygen material, silicon-carbon material.

[0067] In some embodiments, as shown in Figure 1 and Figure 2 the positive electrode tab 10 further includes a positive electrode tab 50 connected to the positive current collector 11 and extending out of the housing 200, and the negative electrode tab 20 further includes a negative electrode tab 60 connected to the negative current collector 21 and extending out of the housing 200.

[0068] In some embodiments, the separator 40 is an insulating film material such as a polyethylene film, a polypropylene film, a polyester film, or a polyimide film.

[0069] In some embodiments, the secondary battery 1000 further includes an electrolyte, which is contained in the housing 200.

[0070] In some embodiments, the electrolyte includes an electrolyte salt. The electrolyte salt includes at least one of an organic lithium salt or an inorganic lithium salt.

[0071] In some embodiments, the electrolyte salt includes, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium bis-trifluoromethanesulfonimide LiN(CF3SO2)2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO2F)2) (LiFSI), lithium hexafluorocerate (LiCsF6), lithium perchlorate (LiClO4), or lithium trifluoromethanesulfonate (LiCF3SO3).

[0072] In some embodiments, as shown in Figure 3 and Figure 4 The first tab 30 further includes a first insulating layer 33 disposed on the second surface 312, which is configured to resist the curling tendency of the first current collector 31. The first insulating layer 33 is configured to reduce the degree and possibility of curling of the first tab 30 due to the coating of the first active material layer 32 on only one surface of the first current collector 31. In this way, the production yield of the cold-pressing process is improved during the production of the secondary battery 1000, and the possibility of separation of the first tab 30 from the separator 40 is reduced during the use of the secondary battery 1000.

[0073] In some embodiments, as shown in Figure 3 and Figure 4 The secondary battery 1000 includes a first adhesive 300 including a first portion 310 and a second portion 320 in an integrated structure, the first portion 310 being adhered to the surface of the electrode assembly 100 on the same side as the first insulating layer 33 in the first direction X, and the second portion 320 being adhered to the surface of the electrode assembly 100 on the side of the second direction Y perpendicular to the first direction X. The first adhesive 300 is configured to provide a binding force to the tabs in the electrode assembly 100 to maintain the stacked state of the tabs and the separator 40 in the electrode assembly 100.

[0074] In some embodiments, the second direction Y is the direction in which the positive tab 50 and the negative tab 60 extend out of the case 200. In other embodiments, the second direction Y is perpendicular to the direction in which the positive tab 50 and the negative tab 60 extend out of the case 200.

[0075] In some embodiments, as shown in Figure 3 and Figure 4 The first insulating layer 33 is disposed on a portion of the second surface 312, and the first portion 310 is adhered to the portion of the second surface 312 not covered by the first insulating layer 33. In this way, the first insulating layer 33 and the first adhesive 300 do not overlap in the first direction X, which is configured to reduce the impact of the first insulating layer 33 on the thickness of the secondary battery 1000, thereby improving the energy density of the secondary battery 1000.

[0076] In some embodiments, as shown in Figure 4As shown, the thickness of the first insulating layer 33 along the first direction X is T1, and 10 pm ≤ T1 ≤ 20 pm. T1 is set to be greater than or equal to 10 pm, so that the thickness of the first insulating layer 33 is not too small, which is conducive to improving the effect of the first insulating layer 33 resisting the curling tendency of the first tab 30; T1 is set to be less than or equal to 20 pm, so that the thickness of the first insulating layer 33 is not too thick, which is conducive to reducing the impact of the setting of the first insulating layer 33 on the thickness of the electrode assembly 100.

[0077] In some embodiments, as shown in Figure 5 and Figure 6 The first insulating layer 33 is arranged on at least part of the surface of the second surface 312. The first insulating layer 33 includes a main body part 331 and a thinned part 332 in a unitary structure, the thickness of the main body part 331 along the first direction X is greater than the thickness of the thinned part 332 along the first direction X; the first part 310 of the first adhesive 300 is bonded to the surface of the thinned part 332 along the first direction X away from the first current collector 31, and the second part 320 is bonded to the surface of the electrode assembly 100 on one side of the second direction Y. The first part 310 is arranged on the thinned part 332, which is conducive to reducing the impact of the thickness of the first adhesive 300 and the first insulating layer 33 on the thickness of the electrode assembly 100; and the arrangement of the thinned part 332 can reduce the degree and possibility of curling of the first tab 30 at the position of the first part 310.

[0078] In some embodiments, the thinned part 332 is formed by removing part of the material of the first insulating layer 33 by laser, only removing the material of part of the area of the first insulating layer 33, which is conducive to improving the processing efficiency, and retaining the thinned part 332, which is conducive to reducing the possibility of laser damage to the first current collector 31.

[0079] In some embodiments, as shown in Figure 6 The thickness of the main body part 331 along the first direction X is T2, and 10 pm ≤ T2 ≤ 20 pm. T2 is set to be greater than or equal to 10 pm, so that the thickness of the main body part 331 is not too small, which is conducive to improving the ability of the main body part 331 to resist curling of the first tab 30; T2 is set to be less than or equal to 20 pm, so that the thickness of the main body part 331 is not too large, which is conducive to reducing the impact of the main body part 331 on the thickness of the electrode assembly 100.

[0080] As an exemplary example, the value of T2 is one of 11 pm, 12 pm, 13 pm, 14 pm, 15 pm, 16 pm, 17 pm, 18 pm, or 19 pm.

[0081] In some embodiments, as shown in Figure 5 and Figure 6As shown, the thickness of the thinning portion 332 along the first direction X is T3, and 2 pm≤T3≤4 pm. T3≥2 pm is set so that the thickness of the thinning portion 332 is not too small, which is conducive to improving the ability of the thinning portion 332 to resist curling of the first tab 30; T3≤4 pm is set so that the thickness of the thinning portion 332 is not too large, which is conducive to reducing the impact of the sum of the thicknesses of the thinning portion 332 and the first portion 310 on the thickness of the secondary battery 1000.

[0082] For example, T3 is one of 2.2 pm, 2.5 pm, 2.7 pm, 3 pm, 3.2 pm, 3.5 pm, or 3.7 pm.

[0083] In some embodiments, as shown in Figure 5 and Figure 6 As shown, the distance between the main body portion 331 and the first portion 310 along the second direction Y is W1, and 0 mm≤W1≤2 mm. W1≤2 mm is set so that the distance between the first portion 310 and the main body portion 331 is not too large, which is conducive to improving the area of the projection of the main body portion 331 along the first direction X, thereby reducing the degree and likelihood of curling of the first tab 30. The value of W1 can be measured with a ruler.

[0084] In some embodiments, as shown in Figure 7 and Figure 8 As shown, the first insulating layer 33 is provided on at least part of the surface of the second face 312, and the thickness of the first insulating layer 33 along the first direction X is T4, and 2 pm≤T4≤4 pm. The first portion 310 of the first adhesive member 300 is bonded to the surface of the first insulating layer 33 along the first direction X away from the first current collector 31. In this embodiment, the thickness of the first insulating layer 33 is obtained after the removal of the material of the first insulating layer 33 after the coating is completed, in other words, the obtaining of the first insulating layer 33 includes the following steps: coating the first insulating layer 33 on the first current collector 31 with a coating device, the thickness of the first insulating layer 33 obtained in this step is greater than 4 pm, after the first tab 30 and the remaining positive and negative tabs 10 and 20 in the electrode assembly 100 are stacked, a thinning operation is performed on the first insulating layer 33 so that the thickness of the first insulating layer 33 is thinned to 2 pm to 4 pm. After the first insulating layer 33 is thinned, the first adhesive member 300 is bonded, which is conducive to reducing the impact of the sum of the thicknesses of the first portion 310 and the first insulating layer 33 on the thickness of the secondary battery 1000. In addition, T4≥2 pm is set so that the thickness of the first insulating layer 33 is not too small, which is conducive to improving the ability of the first insulating layer 33 to resist curling of the first tab 30; T4≤4 pm is set so that the thickness of the first insulating layer 33 is not too large, which is conducive to reducing the impact of the sum of the thicknesses of the first insulating layer 33 and the first portion 310 on the thickness of the secondary battery 1000.

[0085] In embodiments of the present application, the value of T1, T2, T3 and T4 can be measured in the following direction: take a slice of the first tab 30 and place it under a scanning electron microscope (SEM) for observation and measurement. When observing, the viewing angle is perpendicular to the cross section of the slice that is parallel to the first direction X.

[0086] In some embodiments, as shown in Figure 4 , Figure 6 or Figure 8 , the first portion 310 has a thickness T5 along the first direction X, and 8 μm ≤ T5 ≤ 12 μm. T5 is set to be greater than or equal to 8 μm so that the thickness of the first portion 310 is not too small, which is beneficial for reducing the difficulty of producing the first portion 310 and improving the strength of the first portion 310 and reducing the possibility of the first portion 310 being broken due to stress in the first tab 30; T5 is set to be less than or equal to 12 μm so that the thickness of the first portion 310 is not too large, which is beneficial for reducing the influence of the thickness of the first portion 310 on the thickness of the electrode assembly 100.

[0087] As an exemplary example, the value of T5 is one of 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm or 11.5 μm.

[0088] In some embodiments, the value of T5 can be measured in the following direction: take a slice of at least a portion of the first tab 30 to which the first portion 310 is connected and place it under a SEM for observation and measurement. When observing, the viewing angle is perpendicular to the cross section of the slice that is parallel to the first direction X.

[0089] In some embodiments, as shown in Figure 4 , Figure 6 or Figure 8 , the first bonding member 300 further comprises a third portion 330, and the first portion 310 and the third portion 330 are respectively arranged on two surfaces of the electrode assembly 100 that are opposite along the first direction X, so as to further improve the effect of the first bonding member 300 on maintaining the shape of the electrode assembly 100.

[0090] In some embodiments, as shown in Figure 3 , Figure 5 or Figure 7 , the second surface 312 is a polygon, and the first insulating layer 33 contacts any vertex of the second surface 312. In this way, the influence area of the effect of the first insulating layer 33 on resisting curling of the first tab 30 involves any corner position of the first tab 30, which is beneficial for reducing the possibility of the first tab 30 being curled.

[0091] In some embodiments, as shown in Figure 3 , Figure 5 or Figure 7As shown, the first insulating layer 33 contacts any vertex and any edge of the second surface 312. In this way, the influence area of the first insulating layer 33 against the effect of curling of the first tab 30 involves any corner position and any edge of the first tab 30, which is conducive to further reducing the possibility of curling of the first tab 30.

[0092] In some embodiments, the material of the first insulating layer 33 includes a main material and a binder. The main material includes at least one of alumina, boehmite, zirconia or titania, and the mass percentage of the main material is 80% to 99% based on the mass of the first insulating layer 33; the binder includes at least one of styrene-butadiene rubber, polyvinylidene fluoride or polyacrylate, and the mass percentage of the binder is 0.3% to 20% based on the mass of the first insulating layer 33.

[0093] In some embodiments, the first adhesive member 300 includes a substrate layer and a glue layer. In some embodiments, the substrate layer can be selected from one of polyethylene terephthalate, co-extruded polypropylene, oriented polystyrene, thermoplastic polyurethane, polylactic acid, polyolefin, polyimide.

[0094] In some embodiments, the glue 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.

[0095] In some embodiments, the thickness of the first current collector 31 along the first direction X is T6, 8μm≤T6≤12μm. T6≥8μm is set to prevent the thickness of the first current collector 31 from being too thin, which is conducive to reducing the difficulty of manufacturing the first current collector 31, improving the current-carrying capacity and mechanical strength of the first current collector 31, and reducing the possibility of curling of the first tab 30; T6≤12μm is set to prevent the thickness of the first current collector 31 from being too thick, which is conducive to improving the energy density of the secondary battery 1000.

[0096] In some embodiments, the width of the first part 310 along the second direction Y is W2, 4mm≤W2≤12mm. W2≥4mm is set to prevent the width of the first part 310 along the second direction Y from being too small, which is conducive to improving the binding capacity of the first adhesive member 300 to the electrode assembly 100 to maintain the structure of the electrode assembly 100; W2≤12mm is set to prevent the width of the first adhesive member 300 along the second direction Y from being too large, which is conducive to saving materials. The value of W2 can be measured with a ruler.

[0097] As shown in FIG. 1, the first adhesive member 300 is arranged on the first surface 311 of the first tab 30, and the second adhesive member 300 is arranged on the second surface 312 of the second tab 30. Figure 9As shown, the embodiments of the present application also provide a power consuming device 1000, which comprises the secondary battery 1000 according to any one of the foregoing embodiments.

[0098] The embodiments of the present application also provide a method for manufacturing a secondary battery 1000, which comprises the following steps:

[0099] A first electrode sheet 30 is taken, which comprises a first current collector 31 and a first active material layer 32, the first current collector 31 has a first surface 311 and a second surface 312 oppositely arranged along a first direction X, and the first active material layer 32 is arranged on the first surface 311;

[0100] A first insulating layer 33 is arranged on the second surface 312, which covers part of the surface of the second surface 312;

[0101] The first electrode sheet 30 is arranged on the outermost layer of the laminated electrode assembly 100;

[0102] A first adhesive 300 is taken, which is adhered to the part of the surface of the second surface 312 not covered by the first insulating layer 33 and the surface of the electrode assembly 100 on the side of a second direction Y.

[0103] In some embodiments, the method for manufacturing the secondary battery 1000 further comprises the following steps:

[0104] Before the first insulating layer 33 is arranged on the second surface 312, adhesive tape is adhered to part of the surface of the second surface 312;

[0105] After the first insulating layer 33 is arranged on the second surface 312, part of the first insulating layer 33 covers the adhesive tape;

[0106] After the first electrode sheet 30 is arranged on the outermost layer of the laminated electrode assembly 100, the adhesive tape is torn off, so that part of the surface of the second surface 312 is exposed to the first insulating layer 33.

[0107] In other embodiments, the first insulating layer 33 can be removed by laser cleaning.

[0108] The embodiments of the present application also provide another method for manufacturing a secondary battery 1000, which comprises the following steps:

[0109] A first electrode sheet 30 is taken, which comprises a first current collector 31 and a first active material layer 32, the first current collector 31 has a first surface 311 and a second surface 312 oppositely arranged along a first direction X, and the first active material layer 32 is arranged on the first surface 311;

[0110] The first insulating layer 33 is provided on the second face 312, and covers part of the surface of the second face 312;

[0111] The first tab 30 is provided on the outermost layer of the laminated electrode assembly 100;

[0112] The material of part of the first insulating layer 33 is removed to thin the thickness of at least part of the area of the first insulating layer 33 in the first direction X;

[0113] A first adhesive 300 is taken, and part of the first adhesive 300 is adhered to the surface of the thinned area of the first insulating layer 33 facing away from the first current collector 31 in the first direction X, and part of the first adhesive 300 is adhered to the surface of the electrode assembly 100 on the side of the second direction Y.

[0114] In some embodiments, the method for manufacturing the secondary battery 1000 further comprises the following steps:

[0115] The material of part of the first insulating layer 33 is removed by laser removal.

[0116] In some embodiments, the method for manufacturing the secondary battery 1000 further comprises the following steps: using a negative pressure device to suck away the dust generated when the material of part of the first insulating layer 33 is removed by laser removal.

[0117] To verify the influence of the scheme in the embodiments of the present application on the performance of the secondary battery 1000, the inventors conducted the following experiments.

[0118] The experiments include one group of comparative examples and 28 groups of embodiments, and each experimental group is for the manufacture of 32 secondary batteries 1000. In Examples 1-8, the first insulating layer 33 of the secondary battery 1000 covers part of the surface of the second face 312, and the first part 310 of the first adhesive 300 is adhered to the part of the surface of the second face 312 that is not covered by the first insulating layer 33; in Examples 9-20, the first insulating layer 33 includes a main body part 331 and a thinned part 332, and the first part 310 is adhered to the surface of the thinned part 332 facing away from the first current collector 31 in the first direction X; in Examples 21-28, the first insulating layer 33 covers the entire surface of the second face 312, and the first part 310 is adhered to the surface of the first insulating layer 33 facing away from the first current collector 31 in the first direction X. In Examples 1-30, the first tab 30 is a positive tab 10.

[0119] The method for manufacturing the secondary battery 1000 in Example 1 comprises the following steps:

[0120] (1) Preparation of the positive electrode sheet 10: Active material lithium cobaltate (LiCo02), conductive carbon black (Super P), CNT (carbon nanotube), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97.5:0.5:0.5:1.5, and N-methylpyrrolidone (NMP) was added as a solvent to prepare a positive electrode active material having a solid content of 75 wt%, which was then stirred uniformly for use. An aluminum foil was used as the positive electrode current collector 11, and the thickness of the aluminum foil used in each example is described in Table 1. The above active material was uniformly coated on the surface of the positive electrode current collector 11 on one side in the first direction X using a slot coater, and then dried at 90°C to obtain a positive electrode sheet 10 having a positive electrode active material layer 12 coated on one side. At this time, the thickness of the positive electrode active material layer 12 in the first direction X was 50 μm. Thereafter, for the positive electrode sheet 10 disposed on the non-outermost layer of the electrode assembly 100, the above coating step was repeated on the surface of the positive electrode current collector 11 on the other side in the first direction X to obtain a positive electrode sheet 10 having a positive electrode active material layer 12 coated on both sides; and for the positive electrode sheet 10 (first electrode sheet 30) disposed on the outermost layer of the electrode assembly 100, a material for the first insulating layer 33 was coated on the surface (i.e., the second surface 312 described above) of the positive electrode current collector 11 on the other side in the first direction X, and the first insulating layer 33 covered a part of the surface of the second surface 312. The coated positive electrode sheet 10 was then cold-pressed, and after cold-pressing, the thickness of the positive electrode active material layer 12 was 35 μm, and the thickness of the first insulating layer 33 in each example is described in Table 1. The area of the positive electrode current collector 11 that was not covered when the positive electrode active material layer 12 and the first insulating layer 33 were coated was a tab-void area, and the tab-void area was cut to obtain the positive electrode tab 50.

[0121] (2) Preparation of the negative electrode sheet 20: 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 having a weight percentage of 50 wt%, which was then stirred uniformly for use. A copper foil having a thickness of 10 μm was used as the negative electrode current collector 21. The above-mentioned negative electrode active material was uniformly coated on the surface of the negative electrode current collector 21 along one side of the first direction X using a slot coater, and then dried at 110°C to obtain a negative electrode sheet 20 having a negative electrode active material layer 22 coated on one side. Then, the above-mentioned step was repeated on the other side of the negative electrode current collector 21 along the first direction X to obtain a negative electrode sheet 20 having a negative electrode active material layer 22 coated on both sides. At this time, the thickness of the negative electrode active material layer 22 along the first direction X was 55 μm. The coated negative electrode sheet 20 was then cold-pressed, and the thickness of the negative electrode active material layer 22 along the first direction X after cold-pressing was 45 μm. Thereafter, the negative electrode tab 60 was welded to the portion of the negative electrode current collector 21 not covered by the negative electrode active material layer 22. The area of the negative electrode current collector 21 not covered when the negative electrode active material layer 22 was coated was a bare foil area, and the negative electrode tab 60 was obtained by cutting the bare foil area.

[0122] (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 having a lithium salt concentration of 1.15 mol / L.

[0123] (4) Preparation of the separator film 40: A 7 μm thick polyethylene porous polymer film was used as the separator film 40.

[0124] (5) Preparation of the electrode assembly 100: The positive electrode sheet 10, the separator film 40, and the negative electrode sheet 20 were stacked along the thickness direction of the negative electrode sheet 20 to obtain the electrode assembly 100, and the first adhesive 300 was adhered to the electrode assembly 100 to maintain the structure of the electrode assembly 100. The thickness of the first portion 310 of the first adhesive 300 was 12 μm, and the first portion 310 was adhered to the surface of the portion of the second surface 312 not covered by the first insulating layer 310. During the preparation of the electrode assembly 100, the separation of the first electrode sheet 30 from the separator film 40 was monitored, and if the separator film 40 was separated from the first electrode sheet 30, the electrode assembly 100 was no longer assembled with the housing 200, and the secondary battery 1000 was recorded as invalid.

[0125] (6) Assembly of the secondary battery 1000: Place the punched aluminum laminate film into the assembly jig with the punched surface facing upward, and place the electrode assembly 100 into the hole. Apply an external force to press the electrode assembly 100. Then place another punched aluminum laminate film with the punched surface facing downward on the electrode assembly 100, and heat seal the three edges of the two aluminum laminate films by hot pressing. The unsealed edge is the side where the negative tab 60 and the positive tab 50 protrude from the case 200. Then inject the electrolyte through the unsealed edge, and perform vacuum packaging, standing, hot pressing, and shaping, to obtain the secondary battery 1000.

[0126] The preparation steps of the secondary battery 1000 in Comparative Example 1 are basically the same as those in Example 1, except that the first insulating layer 33 in Comparative Example 1 covers the entire surface of the second surface 312, and the first portion of the first adhesive 300 is adhered to the first insulating layer 33.

[0127] The preparation steps of the secondary battery 1000 in Examples 2-8 are basically the same as those in Example 1, except that the data listed in Table 1 are different.

[0128] The preparation steps of the secondary battery 1000 in Examples 9-20 are basically the same as those in Example 1, except that, after the electrode assembly 100 is completed, if the first electrode sheet 30 and the separator 40 are not separated, the first insulating layer 33 is partially removed to form the thinned portion 332 described above, and the portion where the material is not removed is the main body portion 331 described above, and the first portion 310 is adhered to the thinned portion 332.

[0129] The preparation steps of the secondary battery 100 in Examples 21-28 are basically the same as those in Example 1, except that, after the electrode assembly 100 is completed, if the first electrode sheet 30 and the separator 40 are not separated, the first insulating layer 33 is partially removed to form the thinned portion 332 described above, and the portion where the material is not removed is the main body portion 331 described above, and the first portion 310 is adhered to the thinned portion 332.

[0130] After the preparation of the secondary battery 1000 in each example is completed, long cycle tests are performed on each secondary battery 1000, and the test process is as follows:

[0131] 1) The test temperature is maintained at 25°C;

[0132] 2) The secondary battery 1000 is allowed to stand for 30 min;

[0133] 3) 5C constant current charging to 4.25V, and then constant voltage charging to 3C;

[0134] 4) 3C constant current charging to 4.35V, and then constant voltage charging to 1.5C;

[0135] 5) 1.5C constant current charging to 4.45V, then constant voltage charging to 0.05C;

[0136] 6) standing for 5min;

[0137] 7) 0.7C constant current discharging to 3V, recording the first discharge cycle capacity;

[0138] 8) standing for 5min;

[0139] 9) repeating steps 3 to 8 for 800 times.

[0140] The volume energy density of the secondary battery 1000 was calculated, volume energy density = first discharge cycle capacity / (length of the secondary battery x width of the secondary battery x thickness). The volume energy densities of 32 secondary batteries 1000 in the same group were averaged and recorded in Table 1.

[0141] The secondary battery 1000 was disassembled, and the separation of the first electrode sheet 30 and the separator 40 was observed. If the first electrode sheet 30 and the separator 40 were separated, the secondary battery 1000 was recorded as invalid. For each group of examples, the number of invalid secondary batteries 1000 recorded in Table 1 was the sum of the number of invalid secondary batteries 1000 during preparation and the number of invalid secondary batteries 1000 after long cycle.

[0142] The experimental results are shown in Table 1 below.

[0143] Table 1

[0144]

[0145]

[0146] Note: In the table, " / " means no data.

[0147] As can be seen from Table 1, in Examples 1-28, the average value of the volumetric energy density of the secondary battery 1000 is higher than that of Comparative Example 1, and the number of failed secondary batteries 1000 is not significantly different from that of Comparative Example 1. It can be seen that, for the secondary batteries 1000 in Examples 1-8, the first insulating layer 33 and the first adhesive 300 do not overlap in the first direction X, which is conducive to reducing the influence of the arrangement of the first insulating layer 33 on the thickness of the secondary battery 1000, so as to improve the energy density of the secondary battery 1000; for the secondary batteries 1000 in Examples 9-20, the first portion 310 is arranged at the thinned portion 332, which is conducive to reducing the influence of the thickness superposition of the first adhesive 300 and the first insulating layer 33 on the thickness of the secondary battery 1000; for the secondary batteries 1000 in Examples 21-28, the first adhesive 300 is adhered after the first insulating layer 33 is thinned, which is conducive to reducing the influence of the sum of the thicknesses of the first portion 310 and the first insulating layer 33 in the first direction X on the energy density of the secondary battery. On this basis, the anti-curling ability of the first electrode tab 30 of the secondary battery 1000 in Examples 1-28 does not decrease significantly compared with that of Comparative Example 1, and therefore, the secondary battery 1000 provided in the embodiments can improve the energy density while taking into account the anti-curling ability of the first electrode tab 30.

[0148] In Examples 2-4, the thickness T1 of the first insulating layer 33 satisfies 10 μm≤T1≤20 μm, compared with Example 1, the number of failed secondary batteries 1000 in Examples 2-4 is less, and as the thickness of the first insulating layer 33 increases, the volumetric energy density of the secondary battery 1000 shows a downward trend. It can be seen that, by setting T1≥10 μm, the thickness of the first insulating layer 33 is not too small, which is conducive to improving the effect of the first insulating layer 33 resisting the curling trend of the first electrode tab 30; by setting T1≤20 μm, the thickness of the first insulating layer 33 is not too thick, which is conducive to reducing the influence of the arrangement of the first insulating layer 33 on the thickness of the electrode assembly 100.

[0149] In Examples 10-12, the thickness T2 of the main body portion 331 satisfies 10 μm≤T2≤20 μm, compared with Example 9, as the thickness of the main body portion 331 increases, the number of failed secondary batteries 1000 in Examples 10-12 shows a downward trend, and as the thickness of the main body portion 331 increases, the volumetric energy density of the secondary battery 1000 shows a downward trend. It can be seen that, by setting T2≥10 μm, the thickness of the main body portion 331 is not too small, which is conducive to improving the effect of the main body portion 331 resisting the curling trend of the first electrode tab 30; by setting T2≤20 μm, the thickness of the main body portion 331 is not too thick, which is conducive to reducing the influence of the arrangement of the main body portion 331 on the thickness of the electrode assembly 100.

[0150] In embodiments 13-16, as the thickness T3 of the thinning portion 332 increases, the energy density of the secondary battery 1000 has a downward trend. It can be seen that, by setting T3≤4μm, the influence of the sum of the thicknesses of the thinning portion 332 and the first portion 310 on the energy density of the secondary battery 1000 is reduced. In combination with the consideration that the removal of part of the material of the first insulating layer 33 is performed by laser, by setting T3≥2μm, the influence of the energy of the laser on the first current collector 31 is reduced.

[0151] In embodiments 21-24, as the thickness T4 of the first insulating layer 33 increases, the energy density of the secondary battery 1000 has a downward trend. It can be seen that, by setting T4≤4μm, the influence of the sum of the thicknesses of the first insulating layer 33 and the first portion 310 on the energy density of the secondary battery 1000 is reduced. In combination with the consideration that the removal of part of the material of the first insulating layer 33 is performed by laser, by setting T4≥2μm, the influence of the energy of the laser on the first current collector 31 is reduced.

[0152] The thickness of the first current collector 31 of the secondary battery 1000 in embodiments 6-7, the secondary battery 1000 in embodiments 18-19, and the secondary battery 1000 in embodiments 26-27 satisfies 8μm≤T6≤12μm, the number of failures of the secondary battery 1000 in embodiments 6-7 is less than that of embodiment 5, and the volumetric energy density is not lower than that of embodiment 8, the number of failures of the secondary battery 1000 in embodiments 18-19 is less than that of embodiment 17, and the volumetric energy density is not lower than that of embodiment 20, the number of failures of the secondary battery 1000 in embodiments 26-27 is less than that of embodiment 25, and the volumetric energy density is not lower than that of embodiment 28. It can be seen that, by setting T6≥8μm, the thickness of the first current collector 31 is not too thin, which is conducive to reducing the possibility of curling of the first electrode tab 30; by setting T6≤12μm, the thickness of the first current collector 31 is not too thick, which is conducive to improving the energy density of the secondary battery 1000.

[0153] Those skilled in the art should understand that the above embodiments are only used to illustrate the present application, and are not used as limitations 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 made to the above embodiments are within the disclosure range of the present application.

Claims

1. A secondary battery comprising an electrode assembly, the electrode assembly being of a stacked structure, characterized in that, The electrode assembly includes a first tab located at an outermost layer thereof, the first tab including a first current collector and a first active material layer, the first current collector having a first surface and a second surface oppositely arranged along a first direction, the first surface facing an inner side of the electrode assembly, the first active material layer being provided on the first surface; the first tab further includes a first insulating layer, the first insulating layer being provided on a part of a surface of the second surface, the first direction being a thickness direction of the first tab; The secondary battery further includes a first adhesive member, the first adhesive member including a first portion and a second portion in an integral structure, the first portion being adhered to a part of the surface of the second surface not covered by the first insulating layer; The second portion is adhered to a surface of the electrode assembly located on a side in a second direction, the second direction being perpendicular to the first direction.

2. The secondary battery according to claim 1, wherein A thickness of the first insulating layer along the first direction is T1, 10 µm ≤ T1 ≤ 20 µm.

3. A secondary battery comprising an electrode assembly, the electrode assembly being of a stacked structure, characterized by, The electrode assembly includes a first tab located at an outermost layer thereof, the first tab including a first current collector and a first active material layer, the first current collector having a first surface and a second surface oppositely arranged along a first direction, the first surface facing an inner side of the electrode assembly, the first active material layer being provided on the first surface; the first tab further includes a first insulating layer, the first insulating layer being provided on at least a part of a surface of the second surface, the first direction being a thickness direction of the first tab; The secondary battery further includes a first adhesive member, the first adhesive member including a first portion and a second portion in an integral structure, the first insulating layer including a main body portion and a thinned portion in an integral structure, a thickness of the main body portion along the first direction being greater than a thickness of the thinned portion along the first direction; the first portion being adhered to a surface of the thinned portion facing away from the first current collector along the first direction, the second portion being adhered to a surface of the electrode assembly located on a side in a second direction, the second direction being perpendicular to the first direction.

4. The secondary battery according to claim 3, wherein A thickness of the main body portion along the first direction is T2, 10 µm ≤ T2 ≤ 20 µm; and / or A thickness of the thinned portion along the first direction is T3, 2 µm ≤ T3 ≤ 4 µm.

5. The secondary battery according to claim 3, wherein A distance between the main body portion and the first portion along the second direction is W1, 0 mm ≤ W1 ≤ 2 mm.

6. A secondary battery comprising an electrode assembly, the electrode assembly being of a stacked structure, characterized by The electrode assembly includes a first tab located at an outermost layer thereof, the first tab including a first current collector and a first active material layer, the first current collector having a first surface and a second surface oppositely arranged along a first direction, the first surface facing an inner side of the electrode assembly, the first active material layer being provided on the first surface; the first tab further includes a first insulating layer, the first insulating layer being provided on at least a part of a surface of the second surface, the first direction being a thickness direction of the first tab; A thickness of the first insulating layer along the first direction is T4, 2 µm ≤ T4 ≤ 4 µm; The secondary battery further includes a first adhesive member including a first portion and a second portion in a unitary structure, the first portion being adhered to a surface of the first insulating layer facing away from the first current collector in the first direction, and the second portion being adhered to a surface of the electrode assembly on a second direction side, the second direction being perpendicular to the first direction.

7. The secondary battery according to claim 1 or 3 or 6, wherein The first portion has a thickness T5 of 8 μm ≤ T5 ≤ 12 μm in the first direction.

8. The secondary battery according to claim 1 or 3 or 6, wherein The second surface is polygonal, and the first insulating layer contacts any vertex of the second surface.

9. The secondary battery according to claim 8, wherein The first insulating layer contacts any edge of the second surface.

10. The secondary battery according to claim 1, 3 or 6, wherein The material of the first insulating layer includes a main material and an adhesive; The main material includes at least one of alumina, boehmite, zirconia, or titania, and has a mass percentage of 80% to 99% based on the mass of the first insulating layer; The adhesive includes at least one of styrene-butadiene rubber, polyvinylidene fluoride, or polyacrylate, and has a mass percentage of 0.3% to 20% based on the mass of the first insulating layer.

11. The secondary battery according to claim 1 or 3 or 6, wherein The first current collector has a thickness T6 of 8 μm ≤ T6 ≤ 12 μm in the first direction.

12. The secondary battery according to claim 1 or 3 or 6, wherein The first portion has a width W2 of 4 mm ≤ W2 ≤ 12 mm in the second direction.

13. An electrical device, characterized by A secondary battery according to any one of claims 1 to 12.

14. A method for producing a secondary battery, characterized by, The method includes the steps of: A first electrode sheet including a first current collector having a first surface and a second surface disposed opposite to each other in a first direction, and a first active material layer provided on the first surface, and a first insulating layer provided on the second surface to cover a part of the second surface are provided. The first electrode sheet is provided as an outermost layer of a laminated electrode assembly. A first adhesive member is adhered to a part of the second surface not covered by the first insulating layer and a surface of the electrode assembly on a second direction side, the second direction being perpendicular to the first direction. The method includes the steps of:

15. The method of claim 14, wherein the method further comprises the step of: A tape is adhered to a part of the second surface before the first insulating layer is provided on the second surface. ​ The first insulating layer is provided on the second surface, and a part of the first insulating layer is provided on the tape. The tape is removed after the first electrode sheet is provided as an outermost layer of a laminated electrode assembly, and a part of the second surface is exposed from the first insulating layer. A first electrode sheet including a first current collector having a first surface and a second surface disposed opposite to each other in a first direction, and a first active material layer provided on the first surface, and a first insulating layer provided on the second surface to cover a part of the second surface are provided.

16. A method for producing a secondary battery, characterized by, The first insulating layer is provided on the second surface to cover a part of the second surface. The first electrode sheet is provided as an outermost layer of a laminated electrode assembly. A part of the first insulating layer is removed to thin a thickness of at least a part of the first insulating layer in the first direction. ​ ​ A first adhesive member is taken, and a portion of the first adhesive member is adhered to a surface of the first insulating layer thickness reduction region on the side opposite to the first current collector in the first direction, and a portion of the first adhesive member is adhered to a surface of the electrode assembly on the side in the second direction perpendicular to the first direction.

17. The method of claim 16, wherein the second insulating layer is formed by coating a second insulating layer material on the surface of the first insulating layer thickness reduction region. The material of the portion of the first insulating layer is removed using a laser.

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