Roll core structure and battery

Abstract

The utility model provides a roll core structure and a battery, the roll core structure comprises a positive plate, a negative plate, a diaphragm and a conductive member, the positive plate comprises a first current collector and a positive coating, the first current collector comprises a first insulating base layer, a first conductive layer and a second conductive layer, the first insulating base layer is located between the first conductive layer and the second conductive layer, and the second insulating base layer is located between the first conductive layer and the second conductive layer; the sides, away from the first insulating base layer, of the first conductive layer and the second conductive layer are coated with positive electrode coatings. The negative plate comprises a second current collector and a negative coating coated on the second current collector; the diaphragm is positioned between the positive plate and the negative plate; in the first direction, a winding ending area of the positive plate comprises a positive single-layer coating section and a positive empty foil section which are sequentially arranged, the side, facing the center of the winding core, of the positive single-layer coating section is coated with a positive coating, and the side, deviating from the center of the winding core, of the positive single-layer coating section is connected with the side, facing the center of the winding core, of the positive empty foil section through a conductive part. According to the roll core structure and the battery, the charge-discharge and cycle performance of the battery can be ensured.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a core structure and a battery. Background Technology

[0002] Composite current collectors consist of an insulating substrate and conductive layers on both sides of the insulating substrate. Due to the insulating barrier of the insulating substrate, adhesive is usually applied at the end of the core to maintain the bonding and electrical conductivity of the conductive layers on both sides of the insulating substrate. The problem is that after the cell is filled with electrolyte, the electrolyte soaks and penetrates the adhesive paper. This not only weakens the adhesive strength and stability of the adhesive paper, but may also cause the electrolyte to seep in along the tiny gaps between the conductive layers, leading to poor contact between the conductive layers on both sides of the insulating substrate. This makes it difficult to guarantee the performance of batteries using composite current collectors. Utility Model Content

[0003] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a core structure that can ensure stable conductivity of the conductive layers on both sides of the composite current collector, thereby ensuring battery performance.

[0004] This application also proposes a battery having the above-described core structure.

[0005] The core structure according to an embodiment of this application includes a positive electrode sheet, a negative electrode sheet, a separator, and a conductive element;

[0006] A positive electrode sheet includes a first current collector, which includes a first insulating base layer, a first conductive layer, and a second conductive layer. The first insulating base layer is located between the first conductive layer and the second conductive layer. Both the first conductive layer and the second conductive layer are coated with a positive electrode coating on the side away from the first insulating base layer.

[0007] A separator is located between the positive electrode and the negative electrode. Along the first direction, the positive electrode, the separator, and the negative electrode are wound together to form a core. The core includes a core center, and the winding start area of ​​the positive electrode is located at the core center.

[0008] Along the first direction, the winding end area of ​​the positive electrode sheet includes a positive electrode single-layer coating section and a positive electrode empty foil section arranged sequentially. The positive electrode single-layer coating section is coated with a positive electrode coating on the side facing the center of the core. One side of the conductive element is connected to the side of the positive electrode single-layer coating section away from the center of the core, and the other side of the conductive element is connected to the side of the positive electrode empty foil section facing the center of the core.

[0009] According to the winding core structure provided in the embodiments of the present application, the first conductive layer and the second conductive layer are connected and conductive through the conductive member, thus solving the problem of unstable conduction of the first conductive layer and the second conductive layer caused by the soaking of the adhesive paper in the electrolyte, and the conduction between the first conductive layer and the second conductive layer is more stable, which is beneficial to improving the charge-discharge and cycle performance of the winding core structure and prolonging the service life of the winding core structure. In addition, while ensuring the conduction of the first conductive layer and the second conductive layer, the fixing of the positive electrode empty foil segment can also be realized, and the shape of the winding core structure can be fixed.

[0010] According to some embodiments of the present application, the conductive member comprises a conductive base layer, a first adhesive layer and a second adhesive layer, the conductive base layer is located between the first adhesive layer and the second adhesive layer, the positive electrode single-layer coated segment has the first conductive layer on the side away from the winding core center, the first adhesive layer is connected with the first conductive layer, the positive electrode empty foil segment has the second conductive layer on the side facing the winding core center, and the second adhesive layer is connected with the second conductive layer.

[0011] According to some embodiments of the present application, the thickness of the conductive base layer is 0.1 μm to 20 μm, and the thickness of the first adhesive layer or the second adhesive layer is 0.1 μm to 5 μm.

[0012] According to some embodiments of the present application, the winding core structure further comprises an insulating adhesive paper, a part of the insulating adhesive paper is connected to the side of the positive electrode empty foil segment away from the winding core center, and another part of the insulating adhesive paper is connected to the side of the positive electrode single-layer coated segment away from the winding core center.

[0013] The first conductive layer on the side of the positive electrode empty foil segment facing the winding core center abuts against the first conductive layer on the side of the positive electrode single-layer coated segment away from the winding core center.

[0014] According to some embodiments of the present application, along the first direction, the insulating adhesive paper is arranged spaced apart from the conductive member.

[0015] According to some embodiments of the present application, the second current collector comprises a second insulating base layer, a third conductive layer and a fourth conductive layer, the second insulating base layer is located between the third conductive layer and the fourth conductive layer, the third conductive layer and the fourth conductive layer away from the second insulating base layer are coated with a negative electrode coating layer, and along the first direction, the winding starting area of the negative electrode piece comprises the negative electrode empty foil segment and the negative electrode single-layer coated segment arranged in sequence.

[0016] Along the thickness direction of the second current collector, the third conductive layer is connected to the first side of the second insulating base layer, the fourth conductive layer is connected to the second side of the second insulating base layer, and the third conductive layer is electrically connected to the fourth conductive layer.

[0017] According to some embodiments of the present application, the negative electrode empty foil segment comprises a first corner, the negative electrode single-layer coated segment comprises a second corner, along the first direction, the first corner and the second corner are arranged spaced apart, and the end of the negative electrode empty foil segment away from the negative electrode single-layer coated segment faces the second corner.

[0018] The third conductive layer is attached to the fourth conductive layer.

[0019] According to some embodiments of the present application, the length of the positive empty foil section is 2mm to 500mm in the first direction.

[0020] According to some embodiments of the present application, the positive empty foil section comprises a winding tail end, and the distance between the conductive member and the winding tail end is 0.1mm to 200mm in the first direction.

[0021] The battery according to embodiments of the present application comprises a packaging film and the winding core structure in any of the above embodiments, and the packaging film covers the winding core structure.

[0022] The battery according to embodiments of the present application has at least the following beneficial effects: the winding core structure described above can ensure the charge-discharge and cycle performance of the battery, and is beneficial to prolong the service life of the battery.

[0023] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0024] The present application will be further described below in conjunction with the drawings and embodiments, wherein:

[0025] Figure 1 FIG. 1 is a schematic view of the winding core structure according to an embodiment of the present application;

[0026] Figure 2 FIG. 2 is a schematic view of the winding core structure according to another embodiment of the present application; Figure 1 FIG. 3 is a partial schematic view of position A in FIG. 2;

[0027] Figure 3 FIG. 4 is a partial schematic view of position B in FIG. 2; Figure 1

[0028] Figure 4 FIG. 5 is a cross-sectional view of the positive electrode sheet according to an embodiment of the present application;

[0029] Figure 5 FIG. 6 is a cross-sectional view of the negative electrode sheet according to an embodiment of the present application.

[0030] Reference signs: positive electrode sheet 100, first current collector 110, first insulating base layer 111, first conductive layer 112, second conductive layer 113, positive electrode coating layer 120, positive electrode single-layer coating section 130, positive empty foil section 140;

[0031] ​The negative plate 200, the second current collector 210, the second insulating base layer 211, the first side 2111, the second side 2112, the third conductive layer 212, the fourth conductive layer 213, the negative coating layer 220, the negative empty foil segment 230, the first corner 231, the negative single-layer coating segment 240, the second corner 241;

[0032] The separator 300;

[0033] The conductive part 400, the first adhesive layer 410, the second adhesive layer 420, the conductive base layer 430;

[0034] The insulating adhesive paper 500. DETAILED DESCRIPTION

[0035] The embodiments of the present application are described in detail below with reference to the accompanying drawings. The embodiments described below are examples for explaining the present application and should not be understood as limiting the present application.

[0036] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for the purpose of describing the present application and simplifying the description, and therefore cannot be understood as limiting the present application. The device or element indicated by the orientation must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application.

[0037] In the description of the present application, if the meaning of several is more than one, the meaning of multiple is two or more, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If it is described as first, second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of indicated technical features.

[0038] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be broadly understood, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0039] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples.

[0040] The embodiments of the present application are described below in conjunction with the accompanying drawings:

[0041] Reference Figures 1 to 5 According to the winding core structure of the present application, the winding core structure includes a positive electrode sheet 100, a negative electrode sheet 200, a separator 300, and a conductive piece 400. The positive electrode sheet 100 includes a first current collector 110 and a positive electrode coating 120. The first current collector 110 includes a first insulating base layer 111, a first conductive layer 112, and a second conductive layer 113. Along the thickness direction of the first current collector 110, the first insulating base layer 111 is located between the first conductive layer 112 and the second conductive layer 113. The first conductive layer 112 and the second conductive layer 113 are coated with the positive electrode coating 120 on the side away from the first insulating base layer 111. The negative electrode sheet 200 includes a second current collector 210 and a negative electrode coating 220 coated on the second current collector 210. The separator 300 is located between the positive electrode sheet 100 and the negative electrode sheet 200, and is used to block the positive electrode sheet 100 and the negative electrode sheet 200 to avoid short circuit caused by the conduction of the positive electrode sheet 100 and the negative electrode sheet 200.

[0042] The winding core structure includes the wound positive electrode sheet 100, the separator 300, and the negative electrode sheet 200 (all of which are wound along a first direction to form a winding core). The winding core includes a winding core center, and the winding start area of the positive electrode sheet 100 is located at the winding core center. Along the first direction, the winding end area of the positive electrode sheet 100 includes a positive electrode single-layer coating section 130 and a positive electrode empty foil section 140 arranged in sequence. The positive electrode single-layer coating section 130 is coated with the positive electrode coating 120 on the side facing the winding core center. One side of the conductive piece 400 is connected to the side of the positive electrode single-layer coating section 130 away from the winding core center. The other side of the conductive piece 400 is connected to the side of the positive electrode empty foil section 140 facing the winding core center. The conductive piece 400 has a conductive property. Compared with the scheme in which the first insulating piece is fixed by adhesive paper to make the first conductive layer 112 and the second conductive layer 113 on both sides adhere, the conductive piece 400 in the present application electrically connects the first conductive layer 112 and the second conductive layer 113, ensuring the conduction of the first conductive layer 112 and the second conductive layer 113, and thereby benefiting the performance of the winding structure.

[0043] Specifically, the positive electrode sheet 100 and the negative electrode sheet 200 each include a winding start area and a winding end area, which are arranged in sequence along a first direction, i.e., the first direction is unidirectional, and in the flat and unfolded state of the positive electrode sheet 100, the first direction is the direction from the winding start area to the winding end area of the positive electrode sheet 100. Along the first direction, the positive electrode sheet 100, the separator 300, and the negative electrode sheet 200 are kept stacked and wound to form a core structure, and in the positive electrode single-layer coating section 130 and the positive electrode empty-foil section 140, each includes a first insulating base layer 111, a first conductive layer 112, and a second conductive layer 113, and along the thickness direction of the first current collector 110, the first insulating base layer 111 is located between the first conductive layer 112 and the second conductive layer 113, wherein the first conductive layer 112 is located on the side of the positive electrode single-layer coating section 130 away from the core center, the first conductive layer 112 is connected with the conductive piece 400, and the second conductive layer 113 is located on the side of the positive electrode empty-foil section 140 toward the core center, the second conductive layer 113 is connected with the conductive piece 400, realizing the conduction of the first conductive layer 112 and the second conductive layer 113. Compared with the mode of realizing the conduction of the first conductive layer 112 and the second conductive layer 113 by adhering through adhesive paper, the conductive piece 400 can not only fix the positive electrode empty-foil section 140, but also ensure the more stable electrical conduction of the first conductive layer 112 and the second conductive layer 113, which is beneficial to guarantee the charge-discharge and cycle performance of the core structure.

[0044] It should be noted that the first direction is perpendicular to the thickness direction of the first current collector 110, and in different states, the direction of the first direction can be different, for example, when the positive electrode sheet 100, the negative electrode sheet 200, and the separator 300 are wound to form a core, at different positions of the core, the first direction points in different directions, and the first direction is parallel to the length direction of the positive electrode sheet 100 at the current position of the core (if the positive electrode sheet 100 is in a curved state, the first direction is tangent to the surface of the positive electrode sheet 100). When the positive electrode sheet 100, the negative electrode sheet 200, and the separator 300 are unfolded, the first direction is parallel to the length direction of the positive electrode sheet 100, the negative electrode sheet 200, or the separator 300.

[0045] Reference Figures 1 to 5In some embodiments, the conductive member 400 comprises a conductive base layer 430, a first adhesive layer 410 and a second adhesive layer 420, the conductive base layer 430 is located between the first adhesive layer 410 and the second adhesive layer 420, the first adhesive layer 410 and the second adhesive layer 420 have both adhesive properties and conductive properties, and the first adhesive layer 410 and the second adhesive layer 420 are electrically connected with the conductive base layer 430. The positive electrode single-layer coating section 130 has a first conductive layer 112 on the side away from the center of the core, the first adhesive layer 410 is connected with the first conductive layer 112, and the positive electrode empty foil section 140 has a second conductive layer 113 on the side facing the center of the core, the second adhesive layer 420 is connected with the second conductive layer 113, so that the first conductive layer 112 and the second conductive layer 113 are conductive, and the fixing of the positive electrode empty foil section 140 is realized while ensuring the conduction of the first conductive layer 112 and the second conductive layer 113.

[0046] In some embodiments, the conductive base layer 430 is a conductive fiber, the conductive fiber comprises one or more of carbon black and conductive polymer fiber, the first adhesive layer 410 and the second adhesive layer 420 each comprise a rubber adhesive and a conductive filler, and the mass percentage of the conductive filler in the rubber adhesive is 15% to 20%. Thus, the first adhesive layer 410 and the second adhesive layer 420 have both better conductive properties and adhesive properties. The rubber adhesive comprises one or more of silicone rubber, polyurethane rubber, chloroprene rubber, styrene-isoprene-styrene block copolymer rubber and styrene block copolymer rubber, and the rubber as an adhesive has a large difference in polarity with electrolyte, effectively reduces the adsorption of electrolyte, and does not participate in the chemical reaction of electrolyte, so that the adhesion is more stable. The conductive filler comprises one or more of carbon black, graphite, graphene, carbon nanotube, gold, silver and copper, so that the conductive base layer 430, the first adhesive layer 410 and the second adhesive layer 420 each have conductivity, and the first adhesive layer 410 and the second adhesive layer 420 are bonded with the first conductive layer 112, the second conductive layer 113 and the conductive base layer 430 by high-temperature hot melting or the like, which is beneficial to ensure the charge-discharge and cycle performance of the core structure.

[0047] Reference Figures 1 to 5 In some embodiments, the thickness of the conductive base layer 430 is 0.1 to 20 pm, and the thickness of the first adhesive layer 410 or the second adhesive layer 420 is 0.1 to 5 pm. The conductive base layer 430 is used to provide support for the first adhesive layer 410 and the second adhesive layer 420, and the first adhesive layer 410 and the second adhesive layer 420 have both adhesive properties and conductive properties. Defining the thickness range of the conductive base layer 430, the first adhesive layer 410 and the second adhesive layer 420 facilitates the conductive member 400 to better balance the structural stability and conductive adhesive properties.

[0048] For example, the thickness of the conductive base layer 430 can be any one of 0.1 μm, 0.5 μm, 1 μm, 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm and 20 μm, or can also be an interval value with any two of 0.1 μm, 0.5 μm, 1 μm, 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm and 20 μm as the end point values. The thickness of the first adhesive layer 410 or the second adhesive layer 420 can be any one of 0.1 μm, 0.3 μm, 0.5 μm, 0.7 μm, 1 μm, 2 μm, 3 μm, 4 μm and 5 μm, or can also be an interval value with any two of 0.1 μm, 0.3 μm, 0.5 μm, 0.7 μm, 1 μm, 2 μm, 3 μm, 4 μm and 5 μm as the end point values.

[0049] Reference Figures 1 to 5 In some embodiments, the conductive base layer 430 has a width of 1 mm to 50 mm and a length of 2 mm to 150 mm, and the length of the conductive base layer 430 is greater than the width, for example, the width of the conductive base layer 430 is 1 mm and the length is 2 mm, or the width is 10 mm and the length is 20 mm, or the width is 20 mm and the length is 50 mm, or the width is 50 mm and the length is 150 mm, that is, the area of the contact surface of the conductive base layer 430 with the first adhesive layer 410 or the second adhesive layer 420 ranges from 2 mm 2 to 7500 mm 2 The length and width of the conductive base layer 430 can be adjusted adaptively according to the size of the positive electrode sheet 100. The lower limit of the area of the contact surface of the conductive base layer 430 is used to ensure that the positive electrode empty foil area covers the conductive member 400 along the thickness direction of the first current collector 110, and to avoid excessive resistance of the conductive member 400. The upper limit of the area of the contact surface of the conductive base layer 430 is used to avoid the protrusion of the conductive member 400 along the width direction of the first current collector 110, so that the core structure is more compact, thereby being beneficial to improve the energy density of the winding structure.

[0050] It should be noted that the thickness direction of the first current collector 110, the width direction of the first current collector 110 and the first direction are perpendicular to each other in pairs. The first direction can be understood as the length direction of the first current collector 110.

[0051] Reference Figures 1 to 5In some embodiments, the winding core structure further comprises an insulating adhesive tape 500, a portion of the insulating adhesive tape 500 is connected to the side of the positive electrode empty foil section 140 away from the winding core center, and another portion of the insulating adhesive tape 500 is connected to the side of the positive electrode single-layer coated section 130 away from the winding core center, so as to fix the winding end area of the positive electrode sheet 100 and avoid the winding end area of the positive electrode sheet 100 from being warped. In addition, under the adhesion of the insulating adhesive tape 500, the first conductive layer 112 and the second conductive layer 113 are adhered, so as to ensure the adhesion and conduction of the first conductive layer 112 and the second conductive layer 113 on the basis of the conductive member 400 connecting the positive electrode single-layer coated section 130 and the positive electrode empty foil section 140, and further improve the conduction stability of the first conductive layer 112 and the second conductive layer 113.

[0052] Specifically, the positive electrode empty foil section 140 has a winding tail end, along the first direction, the positive electrode single-layer coated section 130 and the positive electrode empty foil section 140 are arranged in sequence and connected, and the winding tail end of the positive electrode empty foil section 140 is located at the end of the positive electrode empty foil section 140 away from the positive electrode single-layer coated section 130. Along the thickness direction of the first current collector 110, a portion of the insulating adhesive tape 500 is adhered to the first conductive layer 112 of the winding tail end of the positive electrode empty foil section 140, and another portion of the insulating adhesive tape 500 is adhered to the second conductive layer 113 in the positive electrode single-layer coated section 130, so that the second conductive layer 113 in the positive electrode empty foil section 140 abuts against the first conductive layer 112 in the positive electrode single-layer coated section 130, and a new conduction position is added on the basis of the conductive member 400 conducting the first conductive layer 112 and the second conductive layer 113, and the electrical conduction between the first conductive layer 112 and the second conductive layer 113 is more stable.

[0053] It should be understood that, along the first direction, the winding end area of the positive electrode sheet 100 includes the positive electrode empty foil section 140, and the winding tail end of the positive electrode empty foil section 140 is the winding tail end of the positive electrode sheet 100.

[0054] Reference Figures 1 to 5 In some embodiments, along the first direction, the insulating adhesive tape 500 and the conductive member 400 are arranged in a spaced manner, avoiding the lamination of the insulating adhesive tape 500 and the conductive member 400 along the thickness direction of the first current collector 110, avoiding the local protrusion of the winding structure, and making the winding structure more flat.

[0055] Reference Figures 1 to 5 In some other embodiments, along the thickness direction of the first current collector 110, the thickness of the insulating adhesive tape 500 is the same as the thickness of the conductive member 400, further improving the flatness of the side of the winding core structure having the insulating adhesive tape 500 and the conductive member 400, so that the battery pack structure composed of a plurality of winding core structures is more compact, which is beneficial to improve the energy density.

[0056] ReferenceFigures 1 to 5 In some embodiments, the second current collector 210 includes a second insulating base layer 211, a third conductive layer 212, and a fourth conductive layer 213, the second insulating base layer 211 is located between the third conductive layer 212 and the fourth conductive layer 213, and the third conductive layer 212 and the fourth conductive layer 213 are coated with a negative electrode coating 220 on the side away from the second insulating base layer 211. In the first direction, the winding start area of the negative electrode sheet 200 includes a negative electrode empty foil segment 230 and a negative electrode single-layer coating segment 240 arranged in sequence. In the thickness direction of the second current collector 210, the third conductive layer 212 is connected to the first side 2111 of the second insulating base layer 211, the fourth conductive layer 213 is connected to the second side 2112 of the second insulating base layer 211, and the third conductive layer 212 is electrically connected to the fourth conductive layer 213.

[0057] For example, the third conductive layer 212 and the fourth conductive layer 213 can be electrically connected through a conductive structure, so that the positive electrode sheet 100 and the negative electrode sheet 200 in the present application are both electrode sheet structures based on composite current collectors, which are beneficial to further improve the charge-discharge and cycle performance of the core structure.

[0058] Reference Figures 1 to 5 In some embodiments, the negative electrode empty foil segment 230 includes a first corner 231, and the negative electrode single-layer coating segment 240 includes a second corner 241, the first corner 231 and the second corner 241 are arranged at intervals in the first direction, and the end of the negative electrode empty foil segment 230 away from the negative electrode single-layer coating segment 240 faces the second corner 241, and the first corner 231 and the second corner 241 are both formed by winding. Wherein, the third conductive layer 212 is attached to the fourth conductive layer 213, which not only ensures the winding of the negative electrode empty foil segment 230 and is beneficial to alleviate the movement of the negative electrode sheet 200 relative to the positive electrode sheet 100 during winding, but also ensures the conduction of the third conductive layer 212 and the fourth conductive layer 213, which is beneficial to improve the charge-discharge performance of the core structure.

[0059] Specifically, the negative electrode empty foil segment 230 includes a first part and a second part connected in sequence, the first part and the second part are arranged in layers in the thickness direction of the second current collector 210 and are connected at the first corner 231, the second part is located on the side of the first part close to the negative electrode single-layer coating segment 240, the third conductive layer 212 in the first part abuts against the third conductive layer 212 in the second part, the third conductive layer 212 in the negative electrode single-layer coating segment 240 is not coated with the negative electrode coating 220, and the third conductive layer 212 in the negative electrode single-layer coating segment 240 abuts against the fourth conductive layer 213 in the second part, so that the third conductive layer 212 and the fourth conductive layer 213 of the negative electrode sheet 200 are in conduction, which is used to ensure the charge-discharge and cycle performance of the core structure, in addition, the pre-winding structure of the negative electrode empty foil segment 230 can also ensure the relative position of the positive electrode sheet 100 and the negative electrode sheet 200 in the first direction.

[0060] It should be noted that the thickness direction of the second current collector 210 is perpendicular to the first direction.

[0061] Reference Figures 1 to 5 In some embodiments, the length of the positive electrode empty foil segment 140 along the first direction is 2 mm to 500 mm, for example, the length a of the positive electrode empty foil segment 140 can be any value in the range of 2 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, 450 mm and 500 mm, or a can also be an interval value with any two values in the range of 2 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, 450 mm and 500 mm as end point values, defining the lower limit of the length of the positive electrode empty foil segment 140 to ensure that the second conductive layer 113 in the positive electrode empty foil area and the first conductive layer 112 in the positive electrode single-layer coating area are conductive, to provide sufficient connection length for the conductive member 400, and defining the upper limit of the length of the positive electrode empty foil segment 140 to reduce the curling and wrinkling of the positive electrode empty foil segment 140, and to improve the energy density of the winding core structure.

[0062] Reference Figures 1 to 5 In other embodiments, the winding core structure includes the conductive member 400 and the insulating adhesive tape 500, and in the positive electrode empty foil segment 140, the conductive member 400 is connected to one side of the positive electrode empty foil segment 140 facing the center of the winding structure, and the insulating adhesive tape 500 is connected to the other side of the positive electrode empty foil segment 140 away from the center of the winding structure, and the lower limit of the length of the positive electrode empty foil segment 140 also ensures that the insulating adhesive tape 500 and the positive electrode empty foil segment 140 are arranged apart along the first direction, avoiding additional increase in the thickness of the winding core structure.

[0063] Reference Figures 1 to 5 In some embodiments, the positive electrode empty foil segment 140 includes a winding tail end, and the distance between the conductive member 400 and the winding tail end of the positive electrode empty foil segment 140 along the first direction is 0.1 mm to 200 mm, defining the lower limit of the distance to ensure that the positive electrode empty foil segment 140 covers the conductive member 400, making the winding core structure more compact and improving the energy density of the winding core structure, and defining the upper limit of the distance to avoid the positive electrode empty foil segment 140 being too long to reduce the energy loss caused by the positive electrode empty foil segment 140.

[0064] For example, the distance b between the conductive member 400 and the winding tail end can be any value in the range of 0.1 mm, 0.5 mm, 1 mm, 3 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, and 200 mm, or the distance b can also be an interval value with any two values in the range of 0.1 mm, 0.5 mm, 1 mm, 3 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, and 200 mm as end point values.

[0065] With reference to Figures 1 to 5 In some other embodiments, the winding core structure includes the insulating adhesive tape 500, and the lower limit of b can also be reserved for the length of the insulating adhesive tape 500 to avoid the insulating adhesive tape 500 and the conductive layer being stacked along the thickness direction of the first current collector 110, which is beneficial to make the winding core structure more flat.

[0066] With reference to Figures 1 to 5 Figures 1 to 5 Figures 1 to 5 Figures 1 to 5 According to the battery of the embodiments of the present application, the battery includes the encapsulation film and the winding core structure in any of the above embodiments, the encapsulation film encapsulates the winding core structure, the winding core structure ensures the conductive capacity of the battery, and thus the battery of the present application has better conductive performance and cycle performance.

[0067] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A core structure, characterized by, The application relates to a battery, comprising: a positive electrode sheet, comprising a first current collector, the first current collector comprising a first insulating base layer, a first conductive layer and a second conductive layer, the first insulating base layer being located between the first conductive layer and the second conductive layer, and the first conductive layer and the second conductive layer being coated with a positive electrode coating on the side away from the first insulating base layer; a negative electrode sheet, comprising a second current collector and a negative electrode coating coated on the second current collector; a separator located between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the separator and the negative electrode sheet are wound to form a winding core along a first direction, the winding core comprising a winding core center, and a winding start area of the positive electrode sheet being located at the winding core center; a conductive piece; wherein, along the first direction, a winding end area of the positive electrode sheet comprises a positive electrode single-layer coating section and a positive electrode empty foil section arranged in sequence, the positive electrode single-layer coating section is coated with a positive electrode coating on the side facing the winding core center, one side of the conductive piece is connected to the side of the positive electrode single-layer coating section away from the winding core center, and the other side of the conductive piece is connected to the side of the positive electrode empty foil section facing the winding core center.

2. The core structure of claim 1, wherein The conductive piece comprises a conductive base layer, a first adhesive layer and a second adhesive layer, the conductive base layer is located between the first adhesive layer and the second adhesive layer, the side of the positive electrode single-layer coating section away from the winding core center has the first conductive layer, the first adhesive layer is connected to the first conductive layer, the side of the positive electrode empty foil section facing the winding core center has the second conductive layer, and the second adhesive layer is connected to the second conductive layer.

3. The core structure of claim 2, wherein The thickness of the conductive base layer is 0.1-20 mu m, and the thickness of the first adhesive layer or the second adhesive layer is 0.1-5 mu m.

4. The core structure of claim 1, wherein The winding core structure further comprises an insulating adhesive paper, one part of the insulating adhesive paper is connected to the side of the positive electrode empty foil section away from the winding core center, and the other part of the insulating adhesive paper is connected to the side of the positive electrode single-layer coating section away from the winding core center. The first conductive layer on the side of the positive electrode empty foil section facing the winding core center abuts against the second conductive layer on the side of the positive electrode single-layer coating section away from the winding core center.

5. The core structure of claim 4, wherein Along the first direction, the insulating adhesive paper and the conductive piece are arranged at intervals.

6. The core structure of claim 1, wherein The second current collector comprises a second insulating base layer, a third conductive layer and a fourth conductive layer, the second insulating base layer being located between the third conductive layer and the fourth conductive layer, and the third conductive layer and the fourth conductive layer being coated with a negative electrode coating on the side away from the second insulating base layer, and along the first direction, a winding start area of the negative electrode sheet comprises a negative electrode empty foil section and a negative electrode single-layer coating section arranged in sequence; wherein, along the thickness direction of the second current collector, the third conductive layer is connected to the first side of the second insulating base layer, the fourth conductive layer is connected to the second side of the second insulating base layer, and the third conductive layer is electrically connected to the fourth conductive layer.

7. The core structure of claim 6, wherein The negative empty foil segment includes a first corner, the negative single-layer coated segment includes a second corner, along the first direction, the first corner is arranged at intervals with the second corner, and one end of the negative empty foil segment away from the negative single-layer coated segment faces the second corner. The third conductive layer is attached to the fourth conductive layer.

8. The core structure of claim 1, wherein The length of the positive empty foil segment along the first direction is 2mm to 500mm.

9. The core structure according to any one of claims 1 to 8, characterized in that, The positive empty foil segment includes a winding tail end, and the distance between the conductive member and the winding tail end along the first direction is 0.1mm to 200mm.

10. A battery, characterized by Comprising: a packaging film; the winding core structure according to any one of claims 1 to 9, and the packaging film is used to cover the winding core structure.

Images