Positive plate, roll core structure and electric equipment

Abstract

The invention relates to the technical field of batteries, and provides a positive plate, a roll core structure and electric equipment, the positive plate comprises a positive plate body, the positive plate body comprises a middle structure and an end structure, a first coating layer of the middle structure has a first thickness, and a first coating layer of the end structure has a second thickness, the second thickness of the first coating layer of the end structure is smaller than the first thickness of the first coating layer of the middle structure, the positive plate further comprises an insulating layer, the insulating layer is arranged at one end of the positive current collector in the width direction, and the insulating layer is covered by the first coating layer and / or the second coating layer. According to the embodiment of the invention, the safety and comprehensive performance of the roll core structure can be improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a positive electrode sheet, a winding core structure and an electrical device. Background Art

[0002] The lithium deposition phenomenon of the battery cell has an important impact on the safety and comprehensive performance of the battery cell. At present, the positive and negative electrode sheets are usually designed with the same thickness, that is, the thickness of the positive electrode sheet along its width is consistent, and the thickness of the negative electrode sheet along its width is consistent. The above structural design of the positive and negative electrode sheets is prone to lithium deposition in the battery cell, and the lithium deposition phenomenon mostly occurs at the edge of the positive or negative electrode sheet, making the safety of the battery cell low and the comprehensive performance low. Summary of the invention

[0003] The present application provides a positive electrode sheet, a winding core structure and an electrical device, which can improve the safety and comprehensive performance of the winding core structure.

[0004] The first aspect of the present application provides a positive electrode sheet, comprising:

[0005] A positive electrode sheet body, the positive electrode sheet body comprising an intermediate structure and an end structure;

[0006] The positive electrode body comprises:

[0007] A positive electrode current collector having a first connection surface and a second connection surface and a first end and a second end along the length direction of the positive electrode current collector;

[0008] A first coating layer formed on the first connecting surface of the positive electrode current collector;

[0009] and a second coating layer formed on the second connection surface of the positive electrode current collector,

[0010] The first coating layer includes a first layer and a second layer, and the second coating layer includes a third layer and a fourth layer.

[0011] The first coating layer of the middle structure has a first thickness, the first coating layer of the end structure has a second thickness, and the second thickness of the first coating layer of the end structure is less than the first thickness of the first coating layer of the middle structure;

[0012] The positive electrode sheet further includes an insulating layer, which is disposed at one end of the positive electrode current collector in a width direction, and the insulating layer is covered by the first coating layer and / or the second coating layer.

[0013] According to the positive electrode sheet described in the first aspect, by designing the thickness of the end structure to be smaller than the thickness of the middle structure, the area corresponding to the end structure on the negative electrode sheet can provide sufficient active lithium ion embedding sites, which can avoid the occurrence of lithium precipitation, thereby improving the safety and comprehensive performance of the battery cell structure. At the same time, by providing an insulating layer, burrs can be prevented from being generated when the positive electrode sheet is die-cut, thereby protecting the positive electrode sheet.

[0014] In a possible implementation, a first end structure is formed in an area adjacent to the first end on the first coating layer, the length of the first end structure is L1, the thickness of the first end structure is H1, the thickness of the first coating layer of the intermediate structure is H, and H1 and H satisfy the relationship: H1-H=-15μm~0μm; and / or,

[0015] A second end structure is formed in an area adjacent to the first end on the second coating layer, wherein the length of the second end structure is L2 and the thickness of the second end structure is H2; a third end structure is formed in an area adjacent to the second end structure on the second coating layer, wherein the length of the third end structure is L3 and the thickness of the third end structure is H3; H2 and H satisfy the relationship: H2-H=-15μm to -1μm, and / or H3 and H satisfy the relationship: H3-H=-15μm to -1μm.

[0016] In a possible implementation, the positive electrode sheet according to claim 2 is characterized in that a fourth end structure is formed in an area adjacent to the second end on the first coating layer, the length of the fourth end structure is L4, the thickness of the fourth end structure is H4, a fifth end structure is formed in an area adjacent to the fourth end structure on the first coating layer, the length of the fifth end structure is L5, the thickness of the fifth end structure is H5, H4 and H satisfy the relationship: H4-H=-15μm~-1μm, and / or H5 and H satisfy the relationship: H5-H=-6μm~-0μm; and / or,

[0017] A sixth end structure is formed in an area adjacent to the second end of the second coating layer. The length of the sixth end structure is L6, the thickness of the sixth end structure is H6, and H6 and H satisfy the relationship: H6-H=-15μm~0μm.

[0018] In one possible implementation, at the first end, the first layer and the second layer are flush, the third layer and the fourth layer are flush, and / or, at the second end, the first layer and the second layer form a tip, and / or, the third layer and the fourth layer form a tip.

[0019] In a possible implementation, at the tip, the first layer covers the second layer, or the first layer is flush with the second layer, or the second layer extends out of the first layer and the extending length is L7, and L7 satisfies the relationship: L7≤2mm;

[0020] And / or, at the tip, the fourth layer covers the third layer, or the fourth layer is flush with the third layer, or the fourth layer extends out of the third layer and the extending length is L8, and L8 satisfies the relationship: L8≤2mm.

[0021] In a possible implementation manner, the first layer and the second layer are both covered on the insulating layer, and the third layer and the fourth layer are both covered on the insulating layer.

[0022] In one possible implementation, an overlapping area overlapping with the first layer and the second layer is formed on the insulating layer, and the length of the overlapping area is W1. The overlapping area includes a first overlapping area formed by the first layer and the insulating layer and a second overlapping area formed by the second layer and the insulating layer. The length of the first overlapping area is W2, and the length of the second overlapping area is W3. W1, W2 and W3 satisfy the relationship: W1=W2+W3, and / or W3 / W1=0~0.75.

[0023] In a possible implementation, the length of the insulating layer is W20, a non-overlapping area is formed on the insulating layer, the length of the non-overlapping area is W4, and W1 and W20 satisfy the relationship: W1 / W20=1 / 300~1 / 2.

[0024] In one possible implementation, a non-tab area is formed on the positive electrode current collector, in which the length of the insulating layer is W30, the length of the non-overlapping area is W5, and W4 and W5 satisfy the relationship: W5 / W4=0.2~0.8.

[0025] In a possible implementation manner, the insulating layer covers the first layer, the second layer covers the insulating layer, the insulating layer covers the fourth layer, and the third layer covers the insulating layer.

[0026] In one possible implementation, an overlapping area overlapping with the first layer and the second layer is formed on the insulating layer, and the length of the overlapping area is W9. The overlapping area includes a third overlapping area formed by the second layer and the insulating layer, and the length of the third overlapping area is W10. The W9 and the W10 satisfy the relationship: W10 / W9=0.08~0.75.

[0027] A second aspect of the present application provides a winding core structure, comprising:

[0028] The positive electrode sheet according to the first aspect;

[0029] Negative electrode;

[0030] and a separator, the separator being arranged between the positive electrode sheet and the negative electrode sheet

[0031] According to the winding core structure described in the second aspect of the present application, the winding core structure has excellent safety performance and comprehensive performance.

[0032] In a possible implementation, the negative electrode sheet includes a negative electrode sheet body, and the negative electrode sheet body includes:

[0033] A negative electrode current collector having a third connection surface and a fourth connection surface and a third end and a fourth end along the length direction of the negative electrode current collector;

[0034] A third coating layer formed on the third connecting surface of the negative electrode current collector;

[0035] and a fourth coating layer formed on the fourth connection surface of the negative electrode current collector,

[0036] The negative electrode current collector, the third coating layer and the fourth coating layer are flush at the third end to form a flush end, and the negative electrode current collector, the third coating layer and the fourth coating layer are not flush at the fourth end to form a non-flung end.

[0037] In one possible implementation, a first region and a second region are formed on the third coating layer and the fourth coating layer, the first region is at a distance S1 from the third end or the fourth end, the thickness of the first region is V1, the second region is at a distance S2 from the third end or the fourth end, the thickness of the second region is V2, and S1, S2, V1 and V2 satisfy the relationship: S1 ≥ 50 mm, V2-V1 = -3 μm to 7 μm.

[0038] In one possible implementation, the third coating layer includes a fifth layer and a sixth layer, the fourth coating layer includes a seventh layer and an eighth layer, at the third end, the fifth layer and the sixth layer form a tip, the seventh layer and the eighth layer form a tip, and at the fourth end, the fifth layer and the sixth layer form a tip, the seventh layer and the eighth layer form a tip.

[0039] In one possible implementation, at the tip, the fifth layer covers the sixth layer, or the fifth layer is flush with the sixth layer, or the sixth layer extends out of the fifth layer and the extending length is S3, and S3 satisfies the relationship: S3≤2mm.

[0040] In a possible implementation, along the winding direction of the winding core structure, the positive electrode sheet is formed with an even end, and the even end is located at the innermost side of the winding core structure and in a straight section.

[0041] In one possible implementation, the negative electrode sheet includes a first-loop structure located on the inner side of the winding core structure, and the first-loop structure includes a single-sided coating layer on the side facing the positive electrode sheet, and the end of the single-sided coating layer does not exceed the center line of the winding core structure.

[0042] A third aspect of the present application provides an electrical device, comprising the winding core structure described in the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art description are briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 A cross-sectional view of a winding core structure provided according to an embodiment of the present application is shown;

[0045] Figure 2 A schematic structural diagram of a straight section of a winding core structure provided according to an embodiment of the present application is shown;

[0046] Figure 3 A cross-sectional view along the length direction of a positive electrode sheet provided according to an embodiment of the present application is shown;

[0047] Figure 4 A schematic diagram of a combined structure of a first layer and a second layer provided in an embodiment of the present application is shown;

[0048] Figure 5 A schematic diagram of another combined structure of a first layer and a second layer provided according to an embodiment of the present application is shown;

[0049] Figure 6 A schematic diagram of a combined structure of a first layer and a second layer according to another embodiment of the present application is shown;

[0050] Figure 7 A cross-sectional view along the width direction of a positive electrode sheet provided according to an embodiment of the present application is shown;

[0051] Figure 8 A cross-sectional view along the width direction of a first coating layer of a positive electrode sheet provided according to an embodiment of the present application is shown;

[0052] Fig. 9 Another cross-sectional view along the width direction of a positive electrode sheet provided according to an embodiment of the present application is shown;

[0053] Fig.10 Another cross-sectional view along the width direction of the first coating layer of a positive electrode sheet provided according to an embodiment of the present application is shown;

[0054] Fig.11 A cross-sectional view along the length direction of a negative electrode sheet provided according to an embodiment of the present application is shown;

[0055] Fig.12 A cross-sectional view along the width direction of a negative electrode sheet provided according to an embodiment of the present application is shown;

[0056] Fig.13 A cross-sectional view along the width direction of another negative electrode sheet provided according to an embodiment of the present application is shown.

[0057] Reference numerals:

[0058] 100-positive electrode sheet body; 101-intermediate structure; 102-end structure; 110-positive electrode current collector; 120-first coating layer; 130-second coating layer; 111-first connection surface; 112-second connection surface; 113-first end; 114-second end; 121-first layer; 122-second layer; 131-third layer; 132-fourth layer; 1021-first end structure; 1022-second end structure; 1023-third end structure; 1024-fourth end structure; 1025-fifth end structure; 1026-sixth end structure;

[0059] 200-negative electrode sheet body; 210-negative electrode current collector; 220-third coating layer; 230-fourth coating layer; 211-third connection surface; 212-fourth connection surface; 213-third end; 214-fourth end; 215-fifth end; 216-sixth end; 221-fifth layer; 222-sixth layer; 231-seventh layer; 232-eighth layer;

[0060] 300 - insulating layer; 310 - overlapping region; 320 - non-overlapping region; 330 - first insulating layer; 340 - second insulating layer; 311 - first overlapping region; 312 - second overlapping region; 313 - third overlapping region;

[0061] 10-positive electrode sheet; 11-glue-applied part; 21-bending part; 22-first circle structure; 23-single-sided coating layer; a-straight end; b-middle area; c-straight section; d-arc section; e-non-straight end; f-tip; g-first area; h-second area;

[0062] 20- negative electrode sheet;

[0063] 30-Diaphragm. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0065] With the development of new energy technologies, batteries are being used more and more widely. Batteries have high energy density, high safety, long service life, and are green and environmentally friendly to the social environment. They have been widely used in passenger cars, commercial vehicles, electric bicycles, heavy trucks, energy storage facilities, battery swap stations, engineering manufacturing, smart equipment and other fields. At the same time, they also promote the sustainable development of communications, medical equipment, energy development and other aspects.

[0066] As the basic component unit of the battery, the performance of the battery cell has an important impact on the overall performance of the battery. The battery cell includes a positive electrode sheet, a negative electrode sheet, and a separator arranged between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet usually includes an aluminum foil and an active material layer coated on the surface of the aluminum foil. The negative electrode sheet usually includes a copper foil and an active material embedding layer coated on the surface of the copper foil. The active material in the active material layer can be embedded in the active material embedding layer. The battery cell releases or stores electric energy through the interaction of the active material in the active material layer and the active material embedding layer. In the above interaction process, the more active material, the more electric energy the battery cell can release or store, which means that the capacity of the battery cell is larger.

[0067] For lithium-ion batteries, the active material in the active material layer refers to lithium ions. When the lithium ions in the battery cannot be embedded in the active material embedding layer, the excess lithium ions will overflow and lithium precipitation will occur, which may cause safety accidents such as battery explosion, or affect the battery's charge and discharge rate, cycle life, energy density, etc., resulting in the comprehensive performance of the battery being affected. In short, lithium precipitation has an important impact on the safety and comprehensive performance of the battery.

[0068] In the core-wound structure, the positive and negative electrodes in the related art usually adopt the design concept of consistent thickness, that is, the thickness of the positive electrode sheet along its width is consistent, and the thickness of the negative electrode sheet along its width is consistent. This design concept of consistent thickness makes it possible that when the positive electrode sheet and the negative electrode sheet are combined to form a core-wound structure or a stacked core structure, the lithium ions on the positive electrode sheet are often unable to be normally embedded in the negative electrode sheet due to insufficient active embedding sites on the negative electrode sheet, resulting in lithium precipitation, and this precipitation phenomenon usually occurs at the edge of the positive electrode sheet or the negative electrode sheet. The reason is that according to the migration direction of lithium ions, lithium ions need to migrate from the positive electrode sheet to the negative electrode sheet. This migration route easily causes lithium ions to gather at the edge of the positive electrode sheet. More specifically, lithium ions are easily gathered in the end edge area of ​​the positive electrode sheet. When the positive and negative electrode sheets adopt the design concept of consistent thickness, it is difficult for the negative electrode sheet to provide sufficient active embedding sites for lithium ions relative to the end edge area of ​​the positive electrode sheet, resulting in lithium precipitation often occurring at the edge of the positive electrode sheet or the negative electrode sheet.

[0069] The design concept of the positive electrode and the negative electrode in the related art will result in low safety and low overall performance of the battery cell.

[0070] Based on the above-mentioned status quo and problems, an embodiment of the present application provides a positive electrode sheet. By using the battery cell formed by the positive electrode sheet (which may be a coiled core structure), lithium ions can be more easily embedded in the negative electrode sheet, thereby improving the safety and overall performance of the battery cell.

[0071] In an embodiment of the present application, the positive electrode sheet has an end structure that is different from that in conventional technology, and the end structure is designed to be thinner than other positions of the positive electrode sheet. The position of the negative electrode sheet corresponding to the end structure can provide more active lithium ion embedding sites, thereby making it easier for lithium ions to detach from the end structure and embed into the negative electrode sheet.

[0072] Based on the positive electrode sheet, the embodiment of the present application also provides a winding core structure, which has excellent comprehensive performance and safety performance.

[0073] In the embodiments of the present application, the above-mentioned performance of the core structure can be achieved by reasonably setting the positive electrode sheet and its position, reasonably setting the negative electrode sheet and its position, and reasonably setting the relationship between the positive electrode sheet and the negative electrode sheet. In the following embodiments, the structural composition of the core structure will be introduced from three aspects. The first aspect is the overall level of the core structure, which mainly involves the positional relationship between the positive electrode sheet and the negative electrode sheet. The second aspect is the individual level of the positive electrode sheet, which mainly involves the structure of the positive electrode sheet and related processes. The third aspect is the individual level of the negative electrode sheet, which mainly involves the structure of the negative electrode sheet and related processes.

[0074] Figure 1 A cross-sectional view of a winding core structure provided according to an embodiment of the present application is shown.

[0075] In the examples of this application, please refer to Figure 1 The winding core structure includes a negative electrode sheet 20, a separator 30 and the above-mentioned positive electrode sheet 10. The separator 30 is arranged between the positive electrode sheet 10 and the negative electrode sheet 20 to form insulation between the positive electrode sheet 10 and the negative electrode sheet 20 to prevent a short circuit from forming between the positive electrode sheet 10 and the negative electrode sheet 20.

[0076] The winding core structure in the embodiment of the present application, based on the setting of the positive electrode sheet 10, can avoid the occurrence of lithium plating and has excellent comprehensive performance and safety performance.

[0077] It should be noted that the following embodiments of the present application will involve descriptions of relevant directions. To facilitate understanding and unify the meanings represented by various directions, the following will be combined with Figure 1 Define the directions of the core structure.

[0078] It can be understood that, for the core structure, it is formed by winding the negative electrode sheet 20, the separator 30 and the positive electrode sheet 10. It can be wound into a cylindrical structure or a square structure. The embodiment of the present application takes the square structure as an example for explanation. In the process of winding into a square structure, the positive electrode sheet 10, the negative electrode sheet 20 and the separator 30 will be wound layer by layer in a clockwise or counterclockwise direction and gradually form a square structure. It can be understood that the length direction of the positive electrode sheet 10, the negative electrode sheet 20 and the separator 30 corresponds to the winding direction of the core structure. After the core structure is formed, the outer surface of the core structure includes two opposite planes and a curved surface connected between the two planes. The length direction and width direction of the core structure can be defined with one of the planes as a reference. Figure 1 In the example shown, the X direction represents the winding direction of the core structure, and also represents the length direction of the positive electrode sheet 10, the negative electrode sheet 20 and the separator 30, the Z direction represents the thickness direction of the core structure, and the width direction Y of the core structure is perpendicular to the X and Z directions.

[0079] In some embodiments, please refer to Figure 1 Along the winding direction of the core structure, the positive electrode sheet 10 is formed with an even end a, which is located at the innermost side of the core structure and in the straight section c.

[0080] Specifically, the end a is the starting end of the positive electrode sheet 10, and the starting end is located in the middle region b of the winding core structure. For a square structure, the cross section of the winding core structure in the length direction is generally an oblong structure, which includes two straight sections c and an arc section d connected between the two straight sections c. The end a is located at the innermost side of the winding core structure and is located in the straight section c. It can be understood that the end a is set in the middle region b and is located at the connection between the straight section c and the arc section d.

[0081] In the above embodiment, the position design of the end a enables the positive electrode sheet 10 to fully utilize the space in the middle area b of the winding structure, which is beneficial to improving the volume energy density and capacity of the battery cell.

[0082] Figure 2 A schematic structural diagram of a straight section of a winding core structure provided according to an embodiment of the present application is shown.

[0083] In some embodiments, please refer to Figure 2 The negative electrode sheet 20 extends out of the positive electrode sheet 10 and the extending length is X1, and X1 satisfies the relationship: X1 = 0.2 mm ~ 2 mm.

[0084] Thus, the negative electrode sheet 20 can cover the positive electrode sheet 10 in the thickness direction of the battery structure, ensuring that the lithium ions released by the positive electrode sheet 10 have sufficient active lithium ion embedding points on the negative electrode sheet 20, ensuring that the negative electrode sheet 20 will not have lithium deposition, thereby ensuring the safety of the winding core structure. In the specific design, X1 can be 0.2mm, 1mm or 2mm.

[0085] In some embodiments, please refer to Figure 2 The separator 30 extends out of the negative electrode sheet 20 and the extending length is X2, and X2 satisfies the relationship: X2 = 0.5 mm ~ 2 mm.

[0086] Thus, the separator 30 can cover the positive electrode sheet 10 and the negative electrode sheet 20. This coverage is the coverage in the thickness direction of the battery structure, which can ensure that the negative electrode sheet 20 will not be short-circuited and ensure the safety performance of the winding core structure. In the specific design, X2 can be 0.5mm, 1mm or 2mm.

[0087] In some embodiments, please refer to Figure 1 The end of the positive electrode sheet 10 along the winding direction has a glue portion 11, and the end of the negative electrode sheet 20 exceeds the end of the positive electrode sheet 10 and the exceeding length is X3, and X3 satisfies the relationship: X3≥2mm.

[0088] Specifically, the starting end of the positive electrode sheet 10, i.e., the end a, is glued to form a glued portion 11. In the middle area b of the winding core structure, the portion of the negative electrode sheet 20 corresponding to the glued portion 11 needs to extend beyond the glued portion 11, for example, Figure 1In the example shown, the negative electrode sheet 20 is wound from the starting end and forms a bent portion 21 at a position corresponding to the adhesive portion 11, and the bent portion 21 here needs to exceed the adhesive portion 11. Designing X3 to the above size can ensure that there is a misalignment distance between the end of the negative electrode sheet 20 and the end of the positive electrode sheet 10, and can ensure that the negative electrode sheet 20 has sufficient space to correspond to the end of the positive electrode sheet 10, ensure that the lithium ion transmission efficiency is basically consistent and has sufficient lithium ion active embedding points, and ensure that the negative electrode sheet 20 will not precipitate lithium, thereby improving the safety and comprehensive performance of the winding structure.

[0089] In some embodiments, the negative electrode sheet 20 includes a first coil structure 22 located inside the core structure, and the first coil structure 22 includes a single-sided coating layer 23 on one side facing the positive electrode sheet 10 , and the end of the single-sided coating layer 23 does not exceed the center line of the core structure.

[0090] exist Figure 1 In the example shown, the negative electrode sheet 20 is located in the innermost layer of the core structure. The first circle structure formed by the negative electrode sheet 20 along the winding direction is the above-mentioned first circle structure 22. The first circle structure 22 includes the starting end of the negative electrode sheet 20 and the above-mentioned bending portion 21. The positive electrode sheet 10 is located on one side of the negative electrode sheet 20. Therefore, a single-sided coating layer 23 corresponding to the positive electrode sheet 10 is formed on the negative electrode sheet 20. The single-sided coating layer 23 is a kind of active material embedding layer mentioned above, which can be made of ink, silicon carbon, silicon oxygen, pure silicon and other materials. The end of the single-sided coating layer 23 does not exceed the center line of the core structure, thereby improving the volume energy density of the battery.

[0091] The above embodiments describe the core structure in detail from the first aspect. It can be seen from the above embodiments that the core structure in the embodiment of the present application can effectively improve the safety and comprehensive performance of the core structure by reasonably designing the arrangement of the positive electrode sheet 10 and the negative electrode sheet 20. The following embodiments will describe the structural composition of the core structure from the second aspect.

[0092] Figure 3 A cross-sectional view along the length direction of a positive electrode sheet provided according to an embodiment of the present application is shown. Figure 3 In an embodiment of the present application, the positive electrode sheet 10 includes a positive electrode sheet body 100, and the positive electrode sheet body 100 includes an intermediate structure 101 and an end structure 102, wherein the first coating layer of the intermediate structure has a first thickness, the first coating layer of the end structure has a second thickness, and the second thickness of the first coating layer of the end structure is less than the first thickness of the first coating layer of the intermediate structure.

[0093] Taking the square structure as an example, when the winding core structure is a square structure, the positive electrode sheet body 100 has four edges. It can be understood that the end structure 102 can be formed on these four edges, or on part of the four edges. The portion of the positive electrode sheet body 100 except the end structure 102 can be understood as the intermediate structure 101.

[0094] Taking the coordinate system in 3 as an example, the first thickness and the second thickness are both dimensions in the Z direction. The second thickness is smaller than the first thickness, which means that the dimension of the first coating layer of the end structure 102 in the Z direction is smaller than the dimension of the first coating layer of the middle structure 101 in the Z direction.

[0095] It should be noted that the positive electrode sheet 10 and the negative electrode sheet 20 usually need to go through a coating process during the production process. The corresponding glue needs to be coated to the appropriate position through a die head to form the positive electrode sheet 10 and the negative electrode sheet 20. During the coating process, the thickness of the positive electrode sheet 10 and the negative electrode sheet 20 will fluctuate (there will also be fluctuations according to the design idea of ​​consistent thickness).

[0096] In the embodiment of the present application, the positive electrode sheet 10, by designing the thickness of the first coating layer of the end structure 102 to be smaller than the thickness of the first coating layer of the middle structure 101, the area corresponding to the end structure 102 on the negative electrode sheet 20 can provide sufficient active lithium ion embedding sites, which can avoid the occurrence of lithium plating, thereby improving the safety and comprehensive performance of the battery cell structure.

[0097] In some embodiments, please refer to Figure 3 The positive electrode sheet 10 includes a positive electrode current collector 110, a first coating layer 120 and a second coating layer 130, and the first coating layer 120 and the second coating layer 130 are disposed on the positive electrode current collector 110. The first coating layer 120 and the second coating layer 130 belong to the category of active material layers.

[0098] The positive electrode current collector 110 needs to be in contact with the first coating layer 120 and the second coating layer 130 to achieve the function of collecting current. The positive electrode current collector 110 has a first connection surface 111 and a second connection surface 112, the first coating layer 120 is formed on the first connection surface 111 of the positive electrode current collector 110, and the second coating layer 130 is formed on the second connection surface 112 of the positive electrode current collector 110.

[0099] The first coating layer 120 may be formed on the positive electrode current collector 110 by coating, and the second coating layer 130 may be formed on the positive electrode current collector 110 by coating.

[0100] In the length direction of the positive electrode collector 110, the positive electrode collector 110 has a first end 113 and a second end 114. The positive electrode collector 110, the first coating layer 120 and the second coating layer 130 are flush at the first end 113 to form an even end a, and the positive electrode collector 110, the first coating layer 120 and the second coating layer 130 are not flush at the second end 114 to form a non-even end e.

[0101] The positive electrode sheet 10 needs to be die-cut during the production process so that two positive electrode sheets 10 are formed on both sides of the die-cutting position. For the two positive electrode sheets 10 formed by die-cutting, one end of each positive electrode sheet 10 will form an even end a. At the even end a, the first coating layer 120, the second coating layer 130 and the positive electrode current collector 110 after die-cutting are flush with each other. Combined with the foregoing, the even end a can be set at the innermost side of the core structure to ensure the volume energy density and capacity of the core structure. On the other hand, for the even end a, when it is set at the innermost side of the core structure, the uniformity of the lithium ion release rate of the innermost side of the core structure can be ensured, and the problem of differences in the lithium ion release rate of the aluminum foil caused by uneven ends can be avoided, thereby avoiding differences in stress distribution on both sides of the aluminum foil, and realizing protection of the internal structure of the battery cell. For the non-even end e, the first coating layer 120 and the second coating layer 130 have different lengths. This length matching design of the non-even end e can make the two sides of the positive electrode sheet 10 have better energy density after being combined.

[0102] In the embodiment of the present application, the thickness of the end structure 102 of the positive electrode sheet 10 can be designed in various ways according to different usage scenarios, and the area size of the end structure 102 and the thickness of the end structure 102 can be designed according to the length dimension of the positive electrode sheet 10. In the following embodiments, multiple end structures 102 will be described one by one. It can be understood that in other embodiments, more end structures 102 can be set. In addition, in order to ensure the balance between energy density and lithium plating efficiency, the end structures 102 located at the first end 113 and the second end 114 of the positive electrode sheet 10 can be designed to be balanced. For example, three end structures 102 can be set at the even end a, and three end structures 102 can also be set at the uneven end e.

[0103] In some embodiments, please refer to Figure 3 A first end structure 1021 is formed on the first coating layer 120 in an area adjacent to the first end 113. The length of the first end structure 1021 is L1, the thickness of the first end structure 1021 is H1, the thickness of the first coating layer of the intermediate structure 101 is H, L1 satisfies the relationship: L1=0mm~2mm, H1 and H satisfy the relationship: H1-H=-15μm~0μm.

[0104] It should be noted here that the value of L1 needs to be at least greater than 0, for example, it can be 1mm, or it can be 2mm, etc. By setting L1 between 0mm and 2mm, the length of the first end structure 1021 can be reasonably planned, and H1-H can be -15μm, -10μm, etc. It can be understood that when the value of L1 is larger, H1-H can take a smaller value. For example, when L1 is 2mm, H1-H can be -15μm, thereby reasonably balancing the length and thickness of the first end structure 1021. The area on the negative electrode sheet 20 corresponding to the first end structure 1021 can provide sufficient lithium ion active embedding sites, and at the same time, the positive electrode sheet 10 can have good strength at the first end structure 1021.

[0105] In some embodiments, please refer to Figure 3 A second end structure 1022 is formed in an area adjacent to the first end 113 on the second coating layer 130, and the length of the second end structure 1022 is L2, and the thickness of the second end structure 1022 is H2. A third end structure 1023 is formed in an area adjacent to the second end structure 1022 on the second coating layer 130, and the length of the third end structure 1023 is L3, and the thickness of the third end structure 1023 is H3. L2 satisfies the relationship: L2=0mm~5mm, H2 and H satisfy the relationship: H2-H=-15μm~-1μm, L3 satisfies the relationship: L3=5mm~30mm, H3 and H satisfy the relationship: H3-H=-15μm~-1μm.

[0106] It should be noted here that the value of L2 needs to be at least greater than 0, for example, it can be 1mm, or 2mm, 5mm, etc. By setting L2 between 0mm and 5mm, the length of the second end structure 1022 can be reasonably planned, and H2-H can be -15μm, -10μm, etc. It can be understood that when the value of L2 is large, H2-H can be a smaller value. For example, when L2 is 5mm, H2-H can be -15μm, thereby reasonably balancing the length and thickness of the second end structure 1022. The area on the negative electrode sheet 20 corresponding to the second end structure 1022 can provide sufficient lithium ion active embedding points, and at the same time, the positive electrode sheet 10 can have good strength at the second end structure 1022. The value of L3 can be 5mm, or 15mm, 30mm, etc. By setting L3 between 5mm and 30mm, the length of the third end structure 1023 can be reasonably planned, and H3-H can be -15μm, -10μm, etc. It can be understood that when L3 takes a larger value, H3-H can take a smaller value. For example, when L3 is 30 mm, H3-H can be -15 μm. This can reasonably balance the length and thickness of the third end structure 1023. The area on the negative electrode sheet 20 corresponding to the third end structure 1023 can provide sufficient active lithium ion embedding sites, and can also make the positive electrode sheet 10 have better strength at the third end structure 1023.

[0107] For the end a of the positive electrode sheet 10, please refer to Figure 3 A first end structure 1021 is formed on the first coating layer 120, and a second end structure 1022 and a third end structure 1023 are formed on the second coating layer 130. The first end structure 1021, the second end structure 1022 and the third end structure 1023 are all one of the end structures 102. The combination of the three can improve the strength of the positive electrode sheet 10 at the first end 113, and the area corresponding to the first end 113 on the negative electrode sheet 20 can provide sufficient active lithium ion embedding sites.

[0108] In some embodiments, a fourth end structure 1024 is formed in an area adjacent to the second end 114 on the first coating layer 120, and the length of the fourth end structure 1024 is L4, and the thickness of the fourth end structure 1024 is H4. A fifth end structure 1025 is formed in an area adjacent to the fourth end structure 1024 on the first coating layer 120, and the length of the fifth end structure 1025 is L5, and the thickness of the fifth end structure 1025 is H5. L4 satisfies the relationship: L4=3mm~10mm, H4 and H satisfy the relationship: H4-H=-15μm~-1μm, L5 satisfies the relationship: L5=10mm~35mm, and H5 and H satisfy the relationship: H5-H=-6μm~-0μm.

[0109] It should be noted here that the value of L4 can be 3mm, 5mm or 10mm, etc. By setting L4 between 3mm and 10mm, the length of the fourth end structure 1024 can be reasonably planned, and H4-H can be -15μm, -10μm, etc. It can be understood that when the value of L4 is large, H4-H can be a smaller value. For example, when L4 is 10mm, H4-H can be -15μm, thereby reasonably balancing the length and thickness of the fourth end structure 1024. The area on the negative electrode sheet 20 corresponding to the fourth end structure can provide sufficient lithium ion active embedding points, and at the same time, the positive electrode sheet can have good strength at the fourth end structure 1024. The value of L5 can be 10mm, 20mm or 35mm, etc. By setting L5 between 10mm and 35mm, the length of the fifth end structure 1025 can be reasonably planned, and H5-H can be -6μm, -2μm, etc. It can be understood that when L5 takes a larger value, H5-H can take a smaller value. For example, when L5 is 35 mm, H5-H can be -6 μm. This can reasonably balance the length and thickness of the fifth end structure 1025. The area on the negative electrode sheet 20 corresponding to the fifth end structure 1025 can provide sufficient active lithium ion embedding sites, and can also make the positive electrode sheet 10 have better strength at the fifth end structure 1025.

[0110] In some embodiments, a sixth end structure 1026 is formed in an area adjacent to the second end 114 on the second coating layer 130, the length of the sixth end structure 1026 is L6, the thickness of the sixth end structure is H6, L6 satisfies the relationship: L6 = 0 mm ~ 7 mm, H6 and H satisfy the relationship, H6-H = -15 μm ~ 0 μm.

[0111] It should be noted here that the value of L6 needs to be at least greater than 0, for example, it can be 1mm, or it can be 3mm, 7mm, etc. By setting L6 between 0mm and 7mm, the length of the sixth end structure 1026 can be reasonably planned, and H6-H can be -15μm, -10μm, etc. It can be understood that when the value of L6 is larger, H6-H can take a smaller value. For example, when L6 is 7mm, H6-H can be -15μm, thereby reasonably balancing the length and thickness of the sixth end structure 1026. The area on the negative electrode sheet 20 corresponding to the sixth end structure 1026 can provide sufficient lithium ion active embedding sites, and at the same time, the positive electrode sheet 10 can have good strength at the sixth end structure 1026.

[0112] For the non-aligned ends of the positive electrode 10, please refer to Figure 3A fourth end structure 1024 and a fifth end structure 1025 are formed on the first coating layer 120, and a sixth end structure 1026 is formed on the second coating layer 130. The fourth end structure 1024, the fifth end structure 1025 and the sixth end structure 1026 are all one of the end structures 102. The combination of the three can enhance the strength of the positive electrode sheet 10 at the second end 114, and the area on the negative electrode sheet 20 corresponding to the second end 114 can provide sufficient active lithium ion embedding sites.

[0113] It can be understood that the first end structure 1021 to the sixth end structure 1026 can be selectively arranged on the positive electrode sheet 10, for example, the first end structure 1021, the second end structure 1022, the fourth end structure 1024 and the sixth end structure 1026 can be arranged. In some specific embodiments, the first end structure 1021 to the sixth end structure 1026 can all be arranged on the positive electrode sheet 10. At this time, from the length direction of the positive electrode sheet 10, the first coating layer 120 is provided with three end structures 102, and the second coating layer 130 is also provided with three end structures 102. From the diagonal direction of the positive electrode sheet 10, the positive electrode sheet 10 is also provided with three end structures 102 in both diagonal directions. Through the staggered arrangement of the number and position of the end structures 102, the strength of the positive electrode sheet 10 can be effectively improved, and at the same time, the positive electrode sheet 10 can maintain the uniformity of releasing lithium ions at the first end 113 and the second end 114.

[0114] The above embodiments mainly design the length and thickness of the end structure 102 from the length direction of the positive electrode sheet 10. In other embodiments, it can be understood that the end structure 102 in the width direction of the positive electrode sheet 10 can also be designed. This part of the end structure 102 can be set according to factors such as the arrangement of the pole ears and the width dimension of the positive electrode sheet 10.

[0115] In the embodiment of the present application, the first coating layer 120 and the second coating layer 130 may adopt a double-layer structure, and different materials may be used in the double-layer structure, thereby increasing the capacity of the core structure.

[0116] In some embodiments, please refer to Figure 3 The first coating layer 120 includes a first layer 121 and a second layer 122, and the second coating layer 130 includes a third layer 131 and a fourth layer 132. At the first end 113, the first layer 121 and the second layer 122 are flush, and the third layer 131 and the fourth layer 132 are flush. At the second end 114, the first layer 121 and the second layer 122 form a tip f with a gradually decreasing thickness, and the third layer 131 and the fourth layer 132 form a tip f with a gradually decreasing thickness. Of course, the tip f can also be of a reduced thickness as a whole.

[0117] In combination with the above, the straight end a is formed by die-cutting the positive electrode sheet 10, and the tip f here is formed by the natural flow and solidification of the glue. At the tip f, the thickness of the positive electrode sheet 10 shows a trend of gradually decreasing, and combined with the aforementioned fourth end structure 1024, the fifth end structure 1025 and the sixth end structure 1026, the lithium deposition efficiency of the positive electrode sheet 10 at the tip f can be guaranteed.

[0118] In some embodiments, the first layer 121 and the third layer 131 are made of a first material, the second layer 122 and the fourth layer 132 are made of a second material, and the first material and the second material are selected from at least one of lithium cobalt oxide, lithium iron phosphate, ternary, and lithium carbonate.

[0119] As an example, the first layer 121 and the third layer 131 can use lithium iron phosphate, and the second layer 122 and the fourth layer 132 can use lithium carbonate. By combining different materials, the capacity can be increased and the long cycle performance of the core structure can be improved.

[0120] At the tip f, different combination structures can be formed between the first layer 121 and the second layer 122, and between the third layer 131 and the fourth layer 132. Figures 4 to 6 For the sake of convenience, the following embodiments will mainly take the combined structure between the first layer 121 and the second layer 122 as an example for explanation, and the third layer 131 and the fourth layer 132 can be designed with reference to the first layer 121 and the second layer 122.

[0121] Figure 4 A schematic diagram of a combined structure of a first layer and a second layer provided in an embodiment of the present application is shown; Figure 5 A schematic diagram of another combined structure of a first layer and a second layer provided according to an embodiment of the present application is shown; Figure 6 A schematic diagram of a combination structure of a first layer and a second layer provided according to an embodiment of the present application is shown.

[0122] In some embodiments, please refer to Figure 4 The first layer 121 covers the second layer 122. In this embodiment, under the premise that the thickness of the first layer 121 and the second layer 122 are the same, the first layer 121 has more materials, and the purpose of uniform lithium deposition can be achieved by reasonably configuring the material selection.

[0123] In some embodiments, please refer to Figure 5 The first layer 121 is flush with the second layer 122 . In this embodiment, under the premise that the thickness of the first layer 121 and the second layer 122 are the same, the first layer 121 and the second layer 122 are made of the same material, which can form a better end structure 102 of the positive electrode sheet 10 .

[0124] In some embodiments, please refer to Figure 6 The second layer 122 extends out of the first layer 121 and the length of the extension is L7. In this embodiment, by reasonably controlling the size of L7, for example, setting L7 to L7≤2mm, on the one hand, the stability of the positive electrode sheet 10 along the length direction can be ensured to ensure the consistency of the capacity. On the other hand, it is beneficial to control the thickness of the end structure 102, thereby ensuring the performance of the positive electrode sheet 10.

[0125] Similarly, at the tip f, the fourth layer 132 covers the third layer 131, or the fourth layer 132 is flush with the third layer 131, or the fourth layer 132 extends out of the third layer 131 and the extended length is L8 (not shown in the figure), and L8 satisfies the relationship: L8≤2mm.

[0126] In the core structure, the pole ear is usually arranged in the width direction of the core structure. In the core structure of the multilayer structure, each layer has a pole ear, and the pole ears of each layer are stacked along the thickness direction of the core structure. The position of the pole ear is prone to cause short circuit, for example, the pole ear is shorted to the adjacent pole piece. In addition, after the positive electrode sheet 10 is die-cut, there may be burrs at the cut of the positive electrode collector 110. After the core structure is formed, these burrs have the risk of piercing the diaphragm 30 and causing short circuit or thermal runaway, thereby affecting the safety performance of the core structure. Therefore, the position corresponding to the positive electrode sheet 10 for forming or connecting the pole ear, that is, one end of the positive electrode sheet 10 along the width direction needs to be sufficiently clean, and it is necessary to ensure that there may be a small amount of burrs at the cut after the positive electrode sheet 10 is die-cut, or there are no burrs. Based on this, the positive electrode sheet 10 in the embodiment of the present application can also be provided with an insulating layer 300 at one end in the width direction, and the insulating layer 300 can wrap the positive electrode collector 110 to prevent the formation of burrs during the die-cutting process.

[0127] Figure 7 A cross-sectional view along the width direction of a positive electrode sheet provided according to an embodiment of the present application is shown; Figure 8 A cross-sectional view of the first coating layer of a positive electrode sheet provided in accordance with an embodiment of the present application along the width direction is shown. Figure 7 The positive electrode sheet 10 also includes an insulating layer 300, which is arranged at one end of the positive electrode collector 110 in the width direction, and the insulating layer 300 is wrapped around the outer periphery of the positive electrode collector 110. When the positive electrode sheet 10 is die-cut, the insulating layer 300 can protect the positive electrode collector 110 and avoid burrs at the cut of the positive electrode collector 110.

[0128] On the basis of setting the insulating layer 300, the embodiment of the present application designs the structure of the insulating layer 300, and its main design idea is to embed the insulating layer 300 into the first coating layer 120 and the second coating layer 130. In other words, the first coating layer 120 and the second coating layer 130 can cover the insulating layer 300, and the first coating layer 120 and the second coating layer 130 can release lithium ions normally. Therefore, it is possible to achieve the capacity of the core structure without affecting the setting of the insulating layer 300.

[0129] In the examples of this application, please refer to Figure 7 and Figure 8 The insulating layer 300 is coated on the outer periphery of the positive electrode current collector 110 and is covered by the first coating layer 120 and / or the second coating layer 130 .

[0130] The coverage here means that there is an overlap between the first coating layer 120 , the second coating layer 130 and the insulating layer 300 , and the insulating layer 300 is covered by the first coating layer 120 and the second coating layer 130 .

[0131] To simplify the description and facilitate understanding, the following embodiments will mainly be described by taking the structural design of the first coating layer 120 and the insulating layer 300 as an example.

[0132] In the first type of embodiments, the first layer 121 and the second layer 122 both cover the insulating layer 300 , and the third layer 131 and the fourth layer 132 both cover the insulating layer 300 .

[0133] In the first type of embodiment, the first layer 121 and the second layer 122 are both covered on the insulating layer 300, which can simplify the surface structure of the positive electrode sheet 10. During coating, two die heads can be used for coating respectively, one of which is used to form the insulating layer 300, and the other is used to form the first layer 121 and the second layer 122, thereby simplifying the coating process.

[0134] In some embodiments, please refer to Figure 8 An overlapping region 310 overlapping the first layer 121 and the second layer 122 is formed on the insulating layer 300 , and the length of the overlapping region 310 is W1 , and W1 satisfies the relationship: W1 = 10 μm to 500 μm.

[0135] It can be understood that the overlapping area 310 is the bonding position of the first coating layer 120 and the insulating layer 300. The size of the overlapping area 310 can indicate the size of the bonding force. When the size of W1 is larger, the bonding force is larger, and the connection strength between the first coating layer 120 and the insulating layer 300 is higher. The insulating layer 300 can effectively connect the positive electrode collector 110 and the first coating layer 120, and can prevent the first coating layer 120 from falling off. When the size of W2 is smaller, the bonding force is smaller, but the first coating layer 120 can release more lithium ions, which can ensure the capacity of the core structure. Designing W1 according to the above size, for example, setting W1 to 10μm, 250μm or 500μm, can improve the bonding force without losing capacity.

[0136] On the other hand, according to the flow and curing of the glue during the coating process, a tip f is also formed at the end of the insulating layer 300 close to the first coating layer 120, so that the thickness of the insulating layer 300 gradually increases in the direction away from the first coating layer 120. Therefore, the larger the size of W1 is designed to be, the more likely it is to cause capacity loss. Designing W1 to be in the range of 10μm to 500μm can avoid capacity loss. In this range, the first coating layer 120 and the insulating layer 300 are basically in contact with each other at the tip f, which will not affect or less affect the release of lithium ions in the first coating layer 120.

[0137] In some embodiments, please refer to Figure 8 The overlapping region 310 includes a first overlapping region 311 formed by the first layer 121 and the insulating layer 300 and a second overlapping region 312 formed by the second layer 122 and the insulating layer 300. The length of the first overlapping region 311 is W2, and the length of the second overlapping region 312 is W3. W1, W2 and W3 satisfy the relationship: W=W1+W2, W3 / W1=0~0.75, W2=10μm~500μm, W3=0μm~250μm.

[0138] Here, the sizes of the first overlapping area 311 and the second overlapping area 312 are mainly designed. It can be seen from the above design that the second overlapping area 312 can be designed to be shorter, which is also based on the consideration of making the first coating layer 120 and the insulating layer 300 overlap through the tip f as much as possible. Designing W1, W2 and W3 according to the above relationship can effectively improve the bonding force and avoid affecting the capacity.

[0139] As an example, W1 can be 500 μm, W2 can be 300 μm, and W3 can be 200 μm. This length combination relationship ensures sufficient connection strength between the insulating layer 300 and the first coating layer 120 while avoiding reduction of capacity.

[0140] In other examples, the combination relationship of W1, W2 and W3 can be changed in various ways. By reasonably configuring the sizes of W1, W2 and W3, it can be ensured that lithium deposition will not occur at the end position of the core structure corresponding to the positive electrode sheet 10 where the insulating layer 300 is provided.

[0141] In some embodiments, please refer to Figure 7 and Figure 8 The length of the insulating layer 300 is W20, a non-overlapping region 320 is formed on the insulating layer 300, the length of the non-overlapping region 320 is W4, W20, W4 and W1 satisfy the relationship: W20=W1+W4, W4=500μm~2990μm.

[0142] Here, the main design is about the total length of the insulating layer 300 and the length relationship of the overlapping area 310. It can be seen from the above design that the length of the non-overlapping area 320 is designed to be longer. This is a design based on die cutting. W4 is designed to be the above size. For example, W4 can take a value of 500μm, 1000μm or 29905μm, etc., thereby ensuring the length of the non-overlapping area 320, facilitating better protection of the positive electrode collector 110 during die cutting, reducing the generation of burrs on the positive electrode collector 110 during die cutting, and thus improving the safety performance of the core structure.

[0143] On the other hand, designing the length of the non-overlapping area 320 to be longer is also beneficial to protecting the positive electrode ear. After the positive electrode ear is connected to the positive electrode collector 110, the non-overlapping area 320 can prevent the positive electrode ear from bending during subsequent processing, thereby avoiding short circuits between the positive electrode ear and adjacent pole pieces and improving the safety performance of the core structure.

[0144] In some embodiments, W1 and W20 satisfy the relationship: W1 / W20=1 / 300~1 / 2.

[0145] Thus, the length ratio of the overlapping area 310 to the insulating layer 300 can be balanced. Designing according to the above dimensions can improve the connection strength between the first coating layer 120 and the insulating layer 300 and avoid capacity loss during die cutting.

[0146] The above is a design for the position on the positive electrode sheet 10 where the positive electrode tab needs to be set. When the position on the positive electrode sheet 10 does not need to be set with the tab, the insulating layer 300 can be designed with other dimensions.

[0147] For example, in some embodiments, see Figure 8A non-tab area is formed on the positive electrode current collector 110. In the non-tab area, the length of the insulating layer 300 is W30, the length of the non-overlapping area 320 is W5, and W30, W4 and W1 satisfy the relationship: W30=W1+W5, W5=100μm~1000μm.

[0148] The non-tab area is a position on the positive electrode sheet 10 where a positive electrode tab is not required. In the non-tab area, the length W5 of the insulating layer 300 can be designed to be smaller than the aforementioned W4. For example, the W5 can be designed to be 100μm, 500μm or 1000μm. W4 is designed according to the above dimensions. On the one hand, it can save the material of the insulating layer 300 and simplify the coating process. On the other hand, when the positive electrode sheet 10 is die-cut, the die-cutting action can be performed on the insulating layer 300. Without damaging the first coating layer 120, the width of the positive electrode sheet 10 can be made as short as possible, thereby reducing the proportion occupied by the insulating layer 300, thereby improving the energy density of the core structure.

[0149] In some embodiments, W4 and W5 satisfy the relationship: W5 / W4=0.2-0.8.

[0150] It can be understood that the value of W5 / W4 can be set according to actual needs. By setting W5 / W4 within the above-mentioned range, when the positive electrode sheet 10 is die-cut, the pole ear area and the non-pole ear area can form a good transition during die-cutting, ensuring that the intersection from cutting along the length direction of the positive electrode sheet 10 to cutting along the width direction of the positive electrode sheet 10 is still in the area where the insulating layer 300 is located, and the positive electrode current collector 110 at this location can be better protected, avoiding the positive electrode current collector 110 at this location from generating burrs due to the long residence time of the die-cutting action, thereby ensuring the safety performance of the core structure.

[0151] In some embodiments, please refer to Figure 7 , the offset distance between the first layer 121 and the third layer 131 is W6, W6 satisfies the relationship: W6 = 0μm ~ 500μm, the offset distance between the second layer 122 and the fourth layer 132 is W7, W7 satisfies the relationship: W7 = 0μm ~ 990μm, the insulating layer 300 includes a first insulating layer 330 connected to the first connecting surface 111 and a second insulating layer 340 connected to the second connecting surface 112, the offset distance between the first insulating layer 330 and the second insulating layer 340 is W8, W8 satisfies the relationship: 0μm ~ 990μm.

[0152] Here, the main focus is on controlling the dislocation that may be formed during the coating process. By designing W6, W7 and W8 according to the above dimensions, guidance can be provided for the coating process. On the basis of meeting the above dimensions, the number of lithium ions that can be released on both sides of the positive electrode current collector 110 is basically the same, which can ensure the consistency of the core structure and avoid lithium deposition on one side of the positive electrode current collector 110 due to uneven release of lithium ions.

[0153] As an example, when higher precision is required, W6 can be 100 μm, W7 can be 100 μm, and W8 can be 100 μm. As another example, when lower precision is required, W6 can be 400 μm, W7 can be 400 μm, and W8 can be 500 μm.

[0154] The above embodiment describes the case where both the first layer 121 and the second layer 122 are covered on the insulating layer 300. In the above embodiment, it can be understood that the various designs of the length can be changed as needed. The above length dimensions represent the dimensions of the corresponding features along the width direction of the positive electrode sheet 10.

[0155] In the second type of embodiments, the insulating layer 300 covers the first layer 121 , the second layer 122 covers the insulating layer 300 , the insulating layer 300 covers the fourth layer 132 , and the third layer 131 covers the insulating layer 300 .

[0156] In the second type of embodiment, a structure in which the insulating layer 300, the first layer 121 and the second layer 122 are combined in pairs is formed, that is, the first layer 121 is combined with the insulating layer 300, and the insulating layer 300 is combined with the second layer 122. This arrangement can enhance the connection strength between the first layer 121, the insulating layer 300 and the second layer 122, while also better ensuring the capacity of the core structure.

[0157] Fig. 9 Another cross-sectional view along the width direction of a positive electrode sheet provided according to an embodiment of the present application is shown; Fig.10 Another cross-sectional view along the width direction of the first coating layer of a positive electrode sheet provided according to an embodiment of the present application is shown. Fig. 9 and Fig.10Combined with the foregoing, the thickness of the insulating layer 300 gradually increases in the direction away from the first coating layer 120. When the insulating layer 300 is set to be combined between the first layer 121 and the second layer 122, during coating, the second layer 122 can be completely coated first, and then the insulating layer 300 is coated, and then the first layer 121 is coated. This structure and coating method can expose the end of the second layer 122, so that the second layer 122 is not affected by the insulating layer 300, and the second layer 122 can release lithium ions normally, thereby ensuring the capacity of the core structure.

[0158] In some embodiments, please refer to Fig.10 An overlapping region 310 overlapping the first layer 121 and the second layer 122 is formed on the insulating layer 300 , and the length of the overlapping region 310 is W9 , and W9 satisfies the relationship: W9 = 20 μm to 500 μm.

[0159] The overlapping area 310 here can be understood based on the insulating layer 300, that is, the insulating layer 300 is combined between the first layer 121 and the second layer 122 to form an overlapping area 310. The size of the overlapping area 310 can indicate the size of the binding force. When the size of W9 is larger, the binding force is larger, and the connection strength between the first coating layer 120 and the insulating layer 300 is higher. The insulating layer 300 can effectively connect the positive electrode collector 110 and the first coating layer 120, and can prevent the first coating layer 120 from falling off. When the size of W9 is smaller, the binding force is smaller, but the first coating layer 120 can release more lithium ions, which can ensure the capacity of the core structure. Designing W9 according to the above size, for example, setting W9 to 20μm, 250μm or 500μm, can improve the binding force without losing capacity.

[0160] On the other hand, according to the flow and curing of the glue during the coating process, a tip f is also formed at the end of the insulating layer 300 close to the first coating layer 120, so that the thickness of the insulating layer 300 gradually increases in the direction away from the first coating layer 120. Therefore, the larger the size of W9 is designed to be, the more likely it is to cause capacity loss. Designing W9 to be in the range of 20μm to 500μm can avoid capacity loss. In this range, the first coating layer 120 and the insulating layer 300 are basically in contact with each other at the tip f, which will not affect or less affect the release of lithium ions in the first coating layer 120.

[0161] In some embodiments, please refer to Fig.10 The overlapping region 310 includes a third overlapping region 313 formed by the second layer 122 and the insulating layer 300 , and the length of the third overlapping region 313 is W10 , W9 and W10 satisfy the relationship: W10 / W9=0.08-0.75, W10=0 μm-250 μm.

[0162] Here, the length of the third overlapping area 313 and the length ratio of the third overlapping area 313 are designed. It can be understood that when the value of W10 is larger, it means that when coating, the contact position of the insulating layer 300 and the second layer 122 is closer to the middle structure 101 of the positive electrode sheet 10. At this time, the thickness of the first coating layer of the end structure 102 of the positive electrode sheet 10 is closer to the thickness of the first coating layer of the middle structure 101. The thickness of the end of the first coating layer 120 of the positive electrode sheet 10 along the width direction can be adjusted. When the thickness difference is smaller, the positive electrode sheet 10 fits more tightly with the diaphragm 30 and the negative electrode sheet 20, thereby reducing the internal resistance of lithium ion migration and improving the smoothness of lithium ion migration, thereby preventing lithium precipitation. Of course, the value of W10 should not be too large, otherwise the lithium ions in the bottom area of ​​the second layer 122 will be difficult to migrate, which will easily cause capacity loss.

[0163] As an example, W10 can be 100 μm, and W9 can be 900 μm. This size relationship can prevent the occurrence of lithium plating while ensuring capacity.

[0164] In some embodiments, please refer to Fig. 9 , the offset distance between the second layer 122 and the fourth layer 132 is W11, W11 satisfies the relationship: W11 = 0μm~980μm, the insulating layer 300 includes a first insulating layer 330 connected to the first connecting surface 111 and a second insulating layer 340 connected to the second connecting surface 112, the offset distance between the first insulating layer 330 and the second insulating layer 340 is W12, W12 satisfies the relationship: 0μm~980μm.

[0165] Here, the main focus is on controlling the dislocation that may be formed during the coating process. By designing W11 and W12 according to the above dimensions, guidance can be provided for the coating process. On the basis of meeting the above dimensions, the number of lithium ions that can be released on both sides of the positive electrode current collector 110 is basically the same, which can ensure the consistency of the core structure and avoid lithium deposition on one side of the positive electrode current collector 110 due to uneven release of lithium ions.

[0166] As an example, when higher precision is required, W11 may be set to 100 μm, and W12 may be set to 100 μm. As another example, when lower precision is required, W11 may be set to 900 μm, and W12 may be set to 900 μm.

[0167] The above embodiment describes the situation where the first layer 121 covers the insulating layer 300, and the insulating layer 300 covers the second layer 122. In the above embodiment, it can be understood that the various designs of the length can be changed as needed. The above length dimensions represent the dimensions of the corresponding features along the width direction of the positive electrode sheet 10.

[0168] The above embodiments provide a detailed description of the structural composition and process of the positive electrode sheet 10. In the above description, it should be further explained that the positive electrode sheet 10 is mainly described from the length direction and the width direction of the positive electrode sheet 10. For example, a first end 113 and a second end 114 are formed in the length direction of the positive electrode sheet 10, and then each end structure 102 is described in detail based on the first end 113 and the second end 114. For another example, one end in the width direction of the positive electrode sheet 10 can be connected to the positive electrode tab, and the positive electrode current collector 110 forms a tab region and a non-tab region at this end, and the relevant design of the insulating layer 300 is described in detail based on this end.

[0169] In the above embodiments, based on the design of each end structure 102 , the occurrence of lithium deposition can be avoided. Based on the design of the insulating layer 300 , the occurrence of lithium deposition can be avoided while protecting the positive electrode sheet 10 .

[0170] In addition to the above-listed embodiments, the negative electrode sheet 20 in the embodiment of the present application may also adopt related designs. The following embodiments will describe the negative electrode sheet 20 in detail.

[0171] Fig.11 A cross-sectional view along the length direction of a negative electrode sheet provided according to an embodiment of the present application is shown. In some embodiments, please refer to Figure 3 The negative electrode sheet 20 includes a negative electrode sheet body 200, and the negative electrode sheet body 200 includes a negative electrode current collector 210, a third coating layer 220 and a fourth coating layer 230. The third coating layer 220 and the fourth coating layer 230 belong to the category of active material embedding layers.

[0172] The negative electrode current collector 210 needs to be in contact with the third coating layer 220 and the fourth coating layer 230 to achieve the function of collecting current. The negative electrode current collector 210 specifically includes a third connecting surface 211 and a fourth connecting surface 212, the third coating layer 220 is formed on the third connecting surface 211 of the negative electrode current collector 210, and the fourth coating layer 230 is formed on the fourth connecting surface 212 of the negative electrode current collector 210.

[0173] The third coating layer 220 may be formed on the negative electrode current collector 210 by coating, and the fourth coating layer 230 may be formed on the negative electrode current collector 210 by coating.

[0174] In the length direction of the negative electrode collector 210, the negative electrode collector 210 has a third end 213 and a fourth end 214. The negative electrode collector 210, the third coating layer 220 and the fourth coating layer 230 are flush at the third end 213 to form an even end a, and the negative electrode collector 210, the third coating layer 220 and the fourth coating layer 230 are not flush at the fourth end 214 to form a non-even end e.

[0175] Different from the aforementioned positive electrode sheet 10, the negative electrode sheet 20 can be formed by coating and rolling without the die-cutting process during production, and has a tip f formed by the flow and solidification of the glue at both the even end a and the uneven end e. Of course, in other embodiments, the negative electrode sheet 20 can also be cut to form a structure without a tip, for example, the tip f can be cut by laser cutting.

[0176] In some embodiments, please refer to Fig.11 A first region g and a second region h are formed on the third coating layer 220 and the fourth coating layer 230. The distance between the first region g and the third end 213 or the fourth end 214 is S1, and the thickness of the first region g is V1. The distance between the second region h and the third end 213 or the fourth end 214 is S2, and the thickness of the second region h is V2. S1, S2, V1 and V2 satisfy the relationship: S1≥50mm, V1=35μm~70μm, S2=3mm~50mm, V2-V1=-3μm~7μm.

[0177] In this embodiment, the thickness design of the negative electrode sheet 20 is similar to that of the positive electrode sheet 10, but the thickness design on the negative electrode sheet 20 is basically opposite to the thickness design of the positive electrode sheet 10, that is, for the negative electrode sheet 20, the thickness of the edge of the negative electrode sheet 20 can be greater than the thickness of the middle area of ​​the negative electrode sheet 20, which is of great significance for ensuring the smooth migration of lithium ions and preventing lithium plating.

[0178] Specifically, in combination with the above, in the second embodiment of the insulating layer 300, the value of W10 can be as large as possible, because the thickness of the end of the first coating layer 120 along the width direction can be controlled, so that the positive electrode sheet 10 can be close to the negative electrode sheet 20, thereby realizing the smooth migration of lithium ions. In combination with other embodiments of the above, an end structure 102 is provided in the length direction of the positive electrode sheet 10, and the thickness of the first coating layer of the end structure 102 is smaller than the thickness of the first coating layer of the middle structure 101 of the positive electrode sheet 10. To compensate for this size design, the thickness of the edge area of ​​the negative electrode sheet 20 in the length direction can be designed to be thicker than the middle area, thereby still making the negative electrode sheet 20 close to the positive electrode sheet 10, so that under the premise of realizing the respective functions of the positive electrode sheet 10 and the negative electrode sheet 20, the smooth migration of lithium ions can be guaranteed, and the lithium ions can be more easily embedded in the negative electrode sheet 20.

[0179] As an example, when H1-H=-15 μm, V2 can be 15 μm or greater than 15 μm, and when H3-H=-15 μm, V1 can be 15 μm or greater than 15 μm.

[0180] It can be understood that S1, S2, V1 and V2 are designed according to the above dimensions and basically correspond to the first end structure 1021 and the third end structure 1023 on the positive electrode sheet 10, which can ensure the stability and consistency of the performance of the core structure.

[0181] Of course, for the negative electrode sheet 20 , the aforementioned first region g and second region h are merely illustrative. In other embodiments, more regions may be formed on the third coating layer 220 and the fourth coating layer 230 . For example, multiple regions may be set according to the end structures 102 of the aforementioned positive electrode sheet 10 .

[0182] The third coating layer 220 and the fourth coating layer 230 in the embodiment of the present application may adopt a double-layer structure, and different materials may be used in the double-layer structure, thereby increasing the capacity of the core structure.

[0183] In some embodiments, please refer to Fig.11 The third coating layer 220 includes a fifth layer 221 and a sixth layer 222, and the fourth coating layer 230 includes a seventh layer 231 and an eighth layer 232. At the third end 213, the fifth layer 221 and the sixth layer 222 form a tip f with a gradually decreasing thickness, and the seventh layer 231 and the eighth layer 232 form a tip f with a gradually decreasing thickness. At the fourth end 214, the fifth layer 221 and the sixth layer 222 form a tip f with a gradually decreasing thickness, and the seventh layer 231 and the eighth layer 232 form a tip f with a gradually decreasing thickness.

[0184] In some embodiments, the fifth layer 221 and the seventh layer 231 are made of a third material, the sixth layer 222 and the eighth layer 232 are made of a fourth material, and the third material and the fourth material are selected from at least one of graphite, silicon carbon, silicon oxygen, and pure silicon.

[0185] As an example, the fifth layer 221 and the seventh layer 231 can be made of graphite, and the sixth layer 222 and the eighth layer 232 can be made of silicon carbon. By combining different materials, the energy density can be improved, and the fast charging performance of the core structure can be improved.

[0186] On the other hand, the above-mentioned material can adopt silicon material, so that the negative electrode sheet 20 can accommodate more active sites of lithium ions, the thickness of the third coating layer 220 and the fourth coating layer 230 can be reduced, and the volume energy density of the core structure can be further increased.

[0187] At the tip f, different combination structures can be formed between the fifth layer 221 and the sixth layer 222, and between the seventh layer 231 and the eighth layer 232. These combination structures can be set with reference to the positive electrode sheet 10. For example, at the tip f, the fifth layer 221 covers the sixth layer 222, or the fifth layer 221 is flush with the sixth layer 222, or the sixth layer 222 extends out of the fifth layer 221 and the extended length is S3 (not shown in the figure), and S3 satisfies the relationship: S3≤2mm.

[0188] Similar to the positive electrode tab described above, the negative electrode sheet 20 also has a tab region, which is used to connect the negative electrode tab. For the negative electrode sheet 20, the position corresponding to the tab region can be designed accordingly.

[0189] Fig.12 A cross-sectional view along the width direction of a negative electrode sheet provided according to an embodiment of the present application is shown; Fig.13 A cross-sectional view of another negative electrode sheet provided in accordance with an embodiment of the present application along the width direction is shown. Fig.12 and Fig.13 , along the width direction of the negative electrode current collector 210, the negative electrode current collector 210 is formed with a fifth end 215 and a sixth end 216, at the fifth end 215, the fifth layer 221 and the sixth layer 222 form a tip f with a gradually decreasing thickness, the seventh layer 231 and the eighth layer 232 form a tip f with a gradually decreasing thickness, or the fifth layer 221 is flush with the sixth layer 222, and the seventh layer 231 is flush with the eighth layer 232.

[0190] Please refer to Fig.12 In the ear area of ​​the negative electrode sheet 20, at the fifth end 215, the fifth layer 221 and the sixth layer 222 form a tip f with a gradually decreasing thickness, and the seventh layer 231 and the eighth layer 232 form a tip f with a gradually decreasing thickness. In order to ensure the edge thickness of the negative electrode sheet 20 at the fifth end 215, increase the active embedding points of lithium ions in the negative electrode sheet 20 and prevent lithium precipitation, the third coating layer 220 formed by the fifth layer 221 and the sixth layer 222 can cover the fourth coating layer 230 formed by the seventh layer 231 and the eighth layer 232, and the misalignment distance between the third coating layer 220 and the fourth coating layer 230 can be as small as possible, for example, controlled within 2 mm.

[0191] Please refer to Fig.13 The negative electrode sheet 20 can be cut by laser so that there is no tip f. Specifically, it can be achieved by the method of glue sticking-coating-tearing glue, or by the aforementioned method of coating, rolling and then laser cutting. Fig.13In the example shown, it can be ensured that there is no misalignment between the third coating layer 220 and the fourth coating layer 230, and that the negative electrode sheet 20 has sufficient active lithium ion embedding sites. At the same time, it can be ensured that the negative electrode sheet 20 can better adhere to the diaphragm 30 and the positive electrode sheet 10, which is beneficial to the transmission of lithium ions and can avoid lithium plating.

[0192] The above design is also applicable to the sixth end 216 and will not be described in detail.

[0193] The above embodiments provide a detailed description of the structural composition and process of the negative electrode sheet 20. In the above description, it should be further explained that the negative electrode sheet 20 is mainly described from the length direction and the width direction of the negative electrode sheet 20. For example, a third end 213 and a fourth end 214 are formed in the length direction of the negative electrode sheet 20, and then the edge thickness of the negative electrode sheet 20 is described in detail based on the third end 213 and the fourth end 214. For another example, the fifth end 215 in the width direction of the negative electrode sheet 20 can be connected to the negative electrode tab, and the negative electrode current collector 210 forms a tab region at this end, and the tip f of the negative electrode sheet 20 and the case where the tip f is not included are described based on the fifth end 215.

[0194] The winding core structure in the embodiment of the present application can be applied to various types of electrical equipment, including passenger cars, commercial vehicles, electric bicycles, heavy trucks, energy storage facilities, battery swap stations, engineering manufacturing equipment, intelligent equipment, etc.

[0195] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0196] In the description of the present application, it should be understood that the terms "including" and "having" and any variations thereof used in the embodiments of the present application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatuses.

[0197] Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense, for example, it can be a fixed connection, it can also be a detachable connection, or it can be integrated; it can be directly connected, or it can be indirectly connected through an intermediate medium, it can make the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In addition, the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

[0198] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A positive electrode sheet, characterized in that: include: A positive electrode sheet body, the positive electrode sheet body comprising an intermediate structure and an end structure; The positive electrode body comprises: A positive electrode current collector having a first connection surface and a second connection surface and a first end and a second end along the length direction of the positive electrode current collector; A first coating layer formed on the first connecting surface of the positive electrode current collector; and a second coating layer formed on the second connection surface of the positive electrode current collector, The first coating layer includes a first layer and a second layer, and the second coating layer includes a third layer and a fourth layer. The first coating layer of the middle structure has a first thickness, the first coating layer of the end structure has a second thickness, and the second thickness of the first coating layer of the end structure is less than the first thickness of the first coating layer of the middle structure; The positive electrode sheet further includes an insulating layer, which is disposed at one end of the positive electrode current collector in a width direction, and the insulating layer is covered by the first coating layer and / or the second coating layer.

2. The positive electrode sheet according to claim 1, characterized in that: A first end structure is formed in an area adjacent to the first end of the first coating layer, the length of the first end structure is L1, the thickness of the first end structure is H1, the thickness of the first coating layer of the intermediate structure is H, and H1 and H satisfy the relationship: H1-H=-15μm~0μm; and / or, A second end structure is formed in an area adjacent to the first end on the second coating layer, wherein the length of the second end structure is L2 and the thickness of the second end structure is H2; a third end structure is formed in an area adjacent to the second end structure on the second coating layer, wherein the length of the third end structure is L3 and the thickness of the third end structure is H3; H2 and H satisfy the relationship: H2-H=-15μm to -1μm, and / or H3 and H satisfy the relationship: H3-H=-15μm to -1μm.

3. The positive electrode sheet according to claim 2, characterized in that: A fourth end structure is formed in an area adjacent to the second end on the first coating layer, the length of the fourth end structure is L4, the thickness of the fourth end structure is H4, a fifth end structure is formed in an area adjacent to the fourth end structure on the first coating layer, the length of the fifth end structure is L5, the thickness of the fifth end structure is H5, H4 and H satisfy the relationship: H4-H=-15μm to -1μm, and / or H5 and H satisfy the relationship: H5-H=-6μm to -0μm; and / or, A sixth end structure is formed in an area adjacent to the second end of the second coating layer. The length of the sixth end structure is L6, the thickness of the sixth end structure is H6, and H6 and H satisfy the relationship: H6-H=-15μm~0μm.

4. The positive electrode sheet according to claim 1, characterized in that: At the first end, the first layer and the second layer are flush, and / or the third layer and the fourth layer are flush, and at the second end, the first layer and the second layer form a tip, and / or the third layer and the fourth layer form a tip.

5. The positive electrode sheet according to claim 4, characterized in that: At the tip, the first layer covers the second layer, or the first layer is flush with the second layer, or the second layer extends out of the first layer and the extending length is L7, and L7 satisfies the relationship: L7≤2mm, And / or, at the tip, the fourth layer covers the third layer, or the fourth layer is flush with the third layer, or the fourth layer extends out of the third layer and the extending length is L8, and L8 satisfies the relationship: L8≤2mm.

6. The positive electrode sheet according to claim 1, characterized in that: The first layer and the second layer are both covered on the insulating layer, and the third layer and the fourth layer are both covered on the insulating layer.

7. The positive electrode sheet according to claim 6, characterized in that: An overlapping area overlapping with the first layer and the second layer is formed on the insulating layer, and the length of the overlapping area is W1. The overlapping area includes a first overlapping area formed by the first layer and the insulating layer and a second overlapping area formed by the second layer and the insulating layer. The length of the first overlapping area is W2, and the length of the second overlapping area is W3. W1, W2 and W3 satisfy the relationship: W1=W2+W3, and / or W3 / W1=0~0.

75.

8. The positive electrode sheet according to claim 7, characterized in that: The length of the insulating layer is W20, a non-overlapping area is formed on the insulating layer, the length of the non-overlapping area is W4, and W1 and W20 satisfy the relationship: W1 / W20=1 / 300~1 / 2.

9. The positive electrode sheet according to claim 8, characterized in that: A non-tab area is formed on the positive electrode current collector. In the non-tab area, the length of the insulating layer is W30, the length of the non-overlapping area is W5, and W4 and W5 satisfy the relationship: W5 / W4=0.2-0.

8.

10. The positive electrode sheet according to claim 1, characterized in that: The insulating layer covers the first layer, the second layer covers the insulating layer, the insulating layer covers the fourth layer, and the third layer covers the insulating layer.

11. The positive electrode sheet according to claim 10, characterized in that: An overlapping area overlapping with the first layer and the second layer is formed on the insulating layer, and the length of the overlapping area is W9. The overlapping area includes a third overlapping area formed by the second layer and the insulating layer, and the length of the third overlapping area is W10. W9 and W10 satisfy the relationship: W10 / W9=0.08~0.

75.

12. A winding core structure, characterized in that: include: The positive electrode sheet according to any one of claims 1 to 11; Negative electrode; and a separator, wherein the separator is disposed between the positive electrode sheet and the negative electrode sheet.

13. The winding core structure according to claim 12, characterized in that: The negative electrode sheet comprises a negative electrode sheet body, and the negative electrode sheet body comprises: A negative electrode current collector having a third connection surface and a fourth connection surface and a third end and a fourth end along the length direction of the negative electrode current collector; A third coating layer formed on the third connecting surface of the negative electrode current collector; and a fourth coating layer formed on the fourth connection surface of the negative electrode current collector, The negative electrode current collector, the third coating layer and the fourth coating layer are flush at the third end to form a flush end, and the negative electrode current collector, the third coating layer and the fourth coating layer are not flush at the fourth end to form a non-flung end.

14. The winding core structure according to claim 13, characterized in that: A first region and a second region are formed on the third coating layer and the fourth coating layer, the first region is at a distance S1 from the third end or the fourth end, the thickness of the first region is V1, the second region is at a distance S2 from the third end or the fourth end, the thickness of the second region is V2, and S1, S2, V1 and V2 satisfy the relationship: S1≥50mm, V2-V1=-3μm~7μm.

15. The winding core structure according to claim 13, characterized in that: The third coating layer includes a fifth layer and a sixth layer, the fourth coating layer includes a seventh layer and an eighth layer, at the third end, the fifth layer and the sixth layer form a tip, the seventh layer and the eighth layer form a tip, and at the fourth end, the fifth layer and the sixth layer form a tip, the seventh layer and the eighth layer form a tip.

16. The winding core structure according to claim 15, characterized in that: At the tip, the fifth layer covers the sixth layer, or the fifth layer is flush with the sixth layer, or the sixth layer extends out of the fifth layer and the extending length is S3, and S3 satisfies the relationship: S3≤2mm.

17. The winding core structure according to claim 12, characterized in that: Along the winding direction of the winding core structure, the positive electrode sheet is formed with an even end, and the even end is located at the innermost side of the winding core structure and in a straight section.

18. An electrical equipment, characterized in that: It comprises a winding core structure according to any one of claims 12 to 17.

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