battery

Abstract

The application provides a battery, which comprises a battery cell, the battery cell comprising a positive plate and a first adhesive, the positive plate, a diaphragm and a negative plate being wound together, the positive plate comprising a positive current collector, a positive active layer and a positive tab, and a plurality of positive tabs forming a positive tab group; the positive plate comprises a positive single-sided area, in the positive single-sided area, the positive active layer is formed on a side surface of the positive current collector facing the winding center of the battery cell, and at least part of the positive single-sided area is arranged on the outermost layer of the battery cell; the positive tab comprises a first positive tab, the first positive tab being led out from the positive current collector of the positive single-sided area; the positive single-sided area comprises a first area, the first area comprising a convex part and a corresponding concave part, the concave part being arranged on a side surface of the positive single-sided area facing the winding center of the battery cell, and the convex part being arranged on a side surface of the positive single-sided area away from the winding center of the battery cell; the first adhesive is arranged on the side surface of the positive single-sided area away from the winding center, and the overlapping area of the first adhesive and the first area accounts for 2% to 70% of the total area of the first area.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more particularly to a battery. Background Technology

[0002] In related technologies, batteries can employ a wound structure, where positive electrode sheets, separators, and negative electrode sheets are stacked and wound together to form a core. The current collector of the positive electrode sheet can lead out multiple positive tabs, which are then gathered together to form a positive tab group. The positive tab group can be connected to corresponding adapters to achieve conductive output, and is bent and positioned on one side of the core height direction to improve the battery's structural compactness.

[0003] However, when the battery is subjected to vibration and impact, the positive electrode tabs are prone to come into contact with the negative electrode, which can cause a short circuit inside the battery and reduce its safety. Summary of the Invention

[0004] This application provides a battery that addresses the problem of insufficient positional stability of the positive electrode tabs in wound cells during drop and long-term cycling, which increases the risk of short circuits. The structural relationship of the first positive electrode tab, the positive electrode single-sided area, and the first adhesive in the cell is designed in a coordinated manner to improve the overall stability and reliability of the cell.

[0005] This application provides a battery, including:

[0006] The battery cell includes a positive electrode sheet, a separator, a negative electrode sheet, and a first adhesive component. The positive electrode sheet, separator, and negative electrode sheet are wound together. The positive electrode sheet includes a positive current collector and a positive active layer disposed on at least one side surface of the positive current collector. The positive electrode sheet also includes a plurality of positive tabs extending from one side of the positive current collector in the width direction and integrally connected with the positive current collector. The plurality of positive tabs are gathered together and connected to form a positive tab group.

[0007] The battery cell includes a first surface and a second surface disposed opposite to each other along a first direction. The positive electrode group includes a stacked segment formed by bending from the first surface to the second surface and a connecting segment connected to the stacked segment. A bending point is formed at the connection between the stacked segment and the connecting segment. Along the second direction, the connecting segment is located on the side of the stacked segment away from the positive current collector.

[0008] The positive electrode sheet includes a positive double-sided region and a positive single-sided region adjacent to each other along its own length direction. In the positive double-sided region, the positive active layer is formed on opposite sides in the thickness direction of the positive current collector. In the positive single-sided region, the positive active layer is formed on the side surface of the positive current collector facing the winding center of the cell. At least part of the positive single-sided region is disposed on the outermost layer of the cell.

[0009] The positive electrode tab includes a first positive electrode tab and a second positive electrode tab. The first positive electrode tab is drawn out from the positive current collector of the single-sided positive electrode region, and the second positive electrode tab is drawn out from the positive current collector of the double-sided positive electrode region.

[0010] The positive electrode single-sided region includes a first region, which has a plurality of protrusions and recesses corresponding to the protrusions. The recesses are located on the side surface of the first region facing the center of the cell winding, and the protrusions are located on the side surface of the first region away from the center of the cell winding.

[0011] The first adhesive is disposed on the side surface of the positive electrode single-sided area away from the winding center, at least a portion of the first adhesive overlaps with at least a portion of the first area, and the overlapping area of ​​the first adhesive and the first area accounts for 2%-70% of the total area of ​​the first area.

[0012] In one possible embodiment, the first positive electrode tab includes a first sub-positive electrode tab, and a positive electrode single-sided region connected to the first sub-positive electrode tab is disposed close to the second surface;

[0013] The first positive electrode tab includes a first stacked segment and a first connecting segment connected to the first stacked segment. The connection between the first stacked segment and the first connecting segment forms a first bending point. Along the second direction, the distance T between the edge of the negative electrode sheet near the first bending point and the first bending point satisfies: 0.2mm≤T≤2mm.

[0014] In one possible embodiment, the width of the first positive electrode tab is greater than the width of the second positive electrode tab;

[0015] And / or, the first positive electrode tab also includes a second sub-positive electrode tab, and the positive electrode single-sided region connected to the second sub-positive electrode tab is disposed close to the first surface.

[0016] In one possible embodiment, the positive electrode single-sided region includes a second region connected to the first region, the second region being located on one side of the first region along a second direction and disposed close to the positive electrode tab, and also includes an insulating coating formed on the positive electrode current collector of the second region and extending to at least a portion of the surface of the first positive electrode tab;

[0017] Along the second direction, the width of the insulating coating in the second region is less than or equal to the width of the second region;

[0018] Along the first direction, the thickness of the insulating coating is less than the thickness of the positive electrode active layer.

[0019] In one possible embodiment, the protrusion height of the protrusion is between 1 μm and 60 μm;

[0020] And / or, the thickness of the first adhesive element is between 10 μm and 30 μm;

[0021] And / or, the ratio of the protrusion height of the protrusion to the thickness of the first adhesive is between 0.04 and 5;

[0022] And / or, the width of the protrusion is between 0.1 mm and 3 mm;

[0023] And / or, the distance between two adjacent protrusions is between 1 mm and 10 mm.

[0024] In one possible embodiment, it further includes a first adapter and a first sub-adhesive, at least a portion of the first adapter overlapping and connecting with the positive electrode group to form an adapter portion;

[0025] At least part of the first sub-adhesive component covers the junction.

[0026] At least part of the first sub-adhesive covers the first positive electrode tab;

[0027] At least part of the first sub-adhesive covers the surface of the positive electrode single-sided area on the side away from the center of the cell winding.

[0028] In one possible embodiment, the overlap between the first sub-adhesive and the positive electrode single-sided area is between 1 mm and 8 mm in the height direction of the cell.

[0029] In one possible embodiment, the first adhesive and at least a portion of the positive electrode single-sided region are disposed on the outermost layer of the cell, and the end of the positive electrode single-sided region opposite to the positive electrode double-sided region constitutes the winding termination end of the positive electrode sheet.

[0030] The first adhesive component also includes a second sub-adhesive component, which is connected to one end of the positive electrode single-sided region that is away from the positive electrode double-sided region;

[0031] And / or, the first adhesive member further includes a third sub-adhesive member, which is located on opposite sides of the positive electrode tab along the second direction;

[0032] And / or, the battery cell includes a flat region and an arc region, with two arc regions formed on both sides of the flat region along a third direction, and the first adhesive also includes a fourth sub-adhesive, which is disposed on at least one arc region;

[0033] In one possible embodiment, the first adhesive further includes a fifth sub-adhesive covering the boundary between the positive electrode double-sided region and the positive electrode single-sided region.

[0034] In one possible embodiment, a second adhesive element is also included.

[0035] Along the first direction, the second adhesive is disposed between two adjacent positive tabs along the first direction to connect the two adjacent positive tabs, and / or, the second adhesive is located on the surface of the first positive tab away from the second positive tab.

[0036] And / or, the projection of the second adhesive element along the first direction is located between the bending point and the edge of the positive electrode sheet near the positive electrode tab.

[0037] In one possible embodiment, the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed along its own thickness direction, and a plurality of negative electrode tabs extending from one side of the negative electrode current collector in the width direction.

[0038] The thickness of the positive electrode current collector is greater than the thickness of the negative electrode current collector;

[0039] And / or, the number of positive electrodes is greater than the number of negative electrodes.

[0040] The battery provided in this application comprises a positive electrode sheet, a separator, and a negative electrode sheet wound together to form a battery cell. A double-sided positive electrode region and a single-sided positive electrode region are arranged sequentially along the winding direction of the positive electrode sheet. This arrangement ensures that the double-sided positive electrode region in the inner layer of the winding bears the main electrochemical reaction area, while the outermost single-sided positive electrode region forms an adhesive and shape-confining outer surface on its side away from the winding center of the battery cell. Multiple positive electrode tabs are led out from the single-sided and double-sided positive electrode regions, and after the battery cell is initially formed, they are gathered to form a group of positive electrode tabs. These tabs are then bent from the first surface to the second surface, folding the group of positive electrode tabs to one side of the battery cell's height direction. Since the first positive tab is led out from the single-sided positive electrode area and the second positive tab is led out from the double-sided positive electrode area, the first and second positive tabs are stacked. The second positive tab can play the main role in transmitting current. The first positive tab is formed on the outermost layer of the positive tab group. Compared with the existing structure of the outermost single-sided positive electrode area of ​​the battery cell, the first positive tab is set on the outermost single-sided positive electrode area of ​​the battery cell. This can fix and limit the first positive tab on the outermost layer, reduce the risk of the first positive tab on the outermost layer being displaced and deformed, and thus reduce the risk of it contacting the negative electrode. This allows the first positive tab to fix the positive tab group, thereby preventing the positive tab group from contacting the edge of the negative electrode near the positive tab group due to vibration and impact when the battery is dropped. This helps to reduce the risk of battery short circuit and improve the battery's drop resistance.

[0041] Because the positive electrode single-sided area has a first region, the first region is provided with several protrusions and corresponding concave parts. The concave parts are provided on the side surface of the positive electrode single-sided area facing the center of the cell winding, and the protrusions are provided on the side surface of the positive electrode single-sided area away from the center of the cell winding. This can increase the extensibility of the positive current collector in the positive electrode single-sided area, thereby improving the problem that the positive electrode single-sided area is prone to curling into the cell due to single-sided coating, and reducing the risk of the first positive electrode tab shifting into the cell due to the curling of the positive electrode single-sided area. After the concave and protrusions are provided on the positive electrode single-sided area, the positive electrode single-sided area has a certain curvature and pre-deformation, which can provide effective support for the positive electrode single-sided area, reduce the stress generated by the bending of the positive electrode tab group, and thus prevent the short circuit problem caused by the positive electrode tab group contacting the negative electrode sheet during battery drop and cycling.

[0042] Since the first adhesive component is located on the surface of the positive electrode single-sided area away from the center of the cell winding, it can provide local reinforcement to the positive electrode single-sided area. This can mitigate the localized stress concentration caused by the recessed and convex structures in the positive electrode single-sided area, leading to localized breakage of the positive electrode sheet and reducing its fixing effect on the first positive electrode tab. It can also suppress excessive outward arching of the positive electrode single-sided area during battery cycling after the recesses and convex structures are present, preventing the first positive electrode tab from pulling and increasing the risk of contact between the first positive electrode tab and the negative electrode sheet. Furthermore, the first adhesive component can restrain the recesses and convex structures, preventing the formation of convex structures from causing the absence of recesses and convex structures in the positive electrode single-sided area. Excessive gap between the region and the separator can lead to poor adhesion. This reduces the warping and folding issues that occur on the positive electrode single-sided area without concave and convex portions. Furthermore, the overlap area between the first adhesive and the first region is controlled to be within the range of 2%-70% of the total area of ​​the first region. This effectively suppresses the tendency of warping, folding, or rolling caused by uneven stress on the positive electrode single-sided area, thus maintaining the insulation gap and structural fit near the positive electrode tabs. It also prevents the first adhesive from increasing the thickness of the cell or from leaching due to excessive electrolyte adsorption, thereby improving the volumetric energy density and cycle performance of the battery.

[0043] Thus, the battery in this embodiment can maintain a relatively stable state during cycle use, preventing short circuits caused by the positive electrode tabs coming into contact with the negative electrode when the battery is dropped, and the battery has high volumetric energy density and cycle performance.

[0044] In addition to the technical problems solved by the embodiments of this application, the technical features constituting the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions described above, other technical problems that the battery provided by this application can solve, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further described in detail in the specific embodiments. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the battery structure provided in an embodiment of this application;

[0047] Figure 2 This is yet another structural schematic diagram of the battery provided in an embodiment of this application;

[0048] Figure 3This is a schematic diagram of the structure of the positive electrode sheet in the battery, located away from the center of the cell winding, provided in an embodiment of this application.

[0049] Figure 4 This is a schematic diagram of the structure of the battery with the positive electrode sheet facing the center of the cell winding, provided in an embodiment of this application.

[0050] Figure 5 This is a schematic diagram of the structure of a single-sided region of the positive electrode in a battery provided in an embodiment of this application;

[0051] Figure 6 This is a schematic diagram of the structure of the double-sided region of the positive electrode in a battery provided in an embodiment of this application;

[0052] Figure 7 This is a schematic diagram of the structure of a battery cell provided in an embodiment of this application;

[0053] Figure 8 for Figure 7 The back view;

[0054] Figure 9 This is a schematic diagram of the structure of the positive electrode and negative electrode in the battery provided in the embodiments of this application.

[0055] Explanation of reference numerals in the attached figures:

[0056] 100 - Battery cell; 100a - First surface; 100b - Second surface;

[0057] 110-Positive electrode sheet; 111-Positive electrode current collector; 112-Positive electrode active layer; 113-Positive electrode tab; 1131-First positive electrode tab; 11311-First sub-positive electrode tab; 11311a-First stacked segment; 11311b-First connecting segment; 11311c-First bending point; 11312-Second sub-positive electrode tab; 1132-Second positive electrode tab; 113'-Positive electrode tab group; 1131'-Stacked segment; 1132'-Connecting segment; 1133'-Bending point; 114-Insulating coating; 110a-Positive electrode double-sided region; 110b-Positive electrode single-sided region; 1101b-First region; 1102b-Second region; 1103b-Third region;

[0058] 120-diaphragm;

[0059] 130 - Negative electrode plate;

[0060] 140 - First sub-adhesive; 141 - First sub-adhesive; 142 - Second sub-adhesive; 143 - Third sub-adhesive; 144 - Fourth sub-adhesive; 145 - Fifth sub-adhesive;

[0061] 150 - Second adhesive component;

[0062] 200 - Housing;

[0063] X - First direction;

[0064] Y - Second direction;

[0065] Z - Third-party orientation. Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0067] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0068] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0069] The terms "first," "second," and "third" (if any) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein.

[0070] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or display that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or display.

[0071] The battery cell can adopt a wound structure, where the positive electrode, separator, and negative electrode are stacked and wound together to form a core. The current collector of the positive electrode can lead out multiple positive tabs, which are then gathered together to form a positive tab group. This positive tab group can be connected to corresponding adapters to achieve conductive output. The tabs are bent and positioned on one side of the core's height direction to improve the battery's structural compactness. However, during use, the positive tab group is prone to relative displacement due to external forces such as vibration and impact after bending, which can cause the positive tab group to contact the edge of the negative electrode, leading to a short circuit in the battery.

[0072] In view of this, embodiments of this application provide a battery in which the cell is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet. The positive electrode sheet has a positive double-sided region and a positive single-sided region disposed adjacent to each other, and at least a portion of the positive single-sided region is located on the outermost layer of the cell. The positive electrode tabs include different positive electrode tabs respectively led out from the positive single-sided region and the positive double-sided region, and are gathered to form a positive electrode tab group. The positive electrode tab group is bent between two surfaces in the thickness direction of the cell to form a stacked segment, a connecting segment, and a bending point. At the same time, corresponding protrusions and concave portions are provided in the positive single-sided region, and a first adhesive member is provided on the side away from the winding center to reduce the risk of battery short circuit and improve the structural stability and cycle performance of the positive electrode sheet.

[0073] The specific implementation of the battery according to the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0074] Reference Figures 1 to 8 As shown, the battery provided in this embodiment includes a cell 100 and a casing 200. The cell 100 is housed within the casing 200. It comprises a positive electrode 110, a separator 120, a negative electrode 130, and a first adhesive member 140. The positive electrode 110, separator 120, and negative electrode 130 are formed into an assembly by winding. The positive electrode 110 includes a positive current collector 111, a positive active layer 112 disposed on at least one surface of the positive current collector 111, and a plurality of positive tabs 113 extending from one side of the width direction of the positive current collector 111 and integrally connected to the positive current collector 111. The plurality of positive tabs 113 are gathered and connected to form a positive tab group 113'. The positive tab group 113' refers to a conductive connection assembly formed by the aggregation of the plurality of positive tabs 113. The positive tab group 113' is used to uniformly lead out the positive current dispersed in each winding layer after the cell 100 is formed.

[0075] The battery cell 100 has a first surface 100a and a second surface 100b disposed opposite each other along a first direction. The positive electrode tab group 113' includes a stacked segment 1131' and a connecting segment 1132' connected to each other. The stacked segment 1131' is connected to the positive electrode current collector 111. The stacked segment 1131' is formed by bending the positive electrode tab group 113' from the first surface 100a to the second surface 100b. The connecting segment 1132' is formed by continuing to bend the positive electrode tab group 113' from the second surface 100b to the first surface 100a. A bending point 1133' is formed at the connection between the stacked segment 1131' and the connecting segment 1132'. Along the second direction, the connecting segment 1132' is located on the side of the stacked segment 1131' away from the positive electrode current collector 111.

[0076] For example, the housing 200 includes a first housing and a second housing that are disposed opposite to each other and connected to each other along a first direction. The first housing has a first cavity and the second housing has a second cavity. The depth of the first cavity is less than the depth of the second cavity. The first surface 100a is disposed corresponding to the bottom wall of the first cavity and the second surface 100b is disposed corresponding to the bottom wall of the second cavity. In this way, when bending the positive electrode tab group 113', the positive electrode tab group 113' is first bent from the first cavity toward the second cavity, so as to facilitate the insertion of the battery cell 100 into the housing and reduce the space occupied by the positive electrode tab group 113' inside the housing 200.

[0077] In some other embodiments, the first housing may not have the first cavity, and only the second housing may have the second cavity.

[0078] The positive electrode sheet 110 includes a positive current collector 111 and a positive active layer 112 disposed along its own thickness direction. The positive electrode sheet 110 includes a positive double-sided region 110a and a positive single-sided region 110b disposed adjacent to each other along its own length direction. In the positive double-sided region 110a, the positive active layer 112 is formed on opposite sides of the positive current collector 111 in the thickness direction. In the positive single-sided region 110b, the positive active layer 112 is formed only on the surface of the positive current collector 111 facing the winding center of the cell 100. At least part of the positive single-sided region 110b is disposed on the outermost layer of the cell 100.

[0079] It should be noted that the positive electrode sheet 110 may also include a positive electrode empty foil area connected to the positive electrode single-sided region 110b, that is, a positive electrode current collector empty foil area on both sides of the positive electrode current collector 111 without a positive electrode active layer 112 in the thickness direction of the positive electrode current collector 111. The positive electrode double-sided region 110a, the positive electrode single-sided region 110b and the positive electrode empty foil area are connected sequentially along the length direction of the positive electrode sheet 110. The battery cell 100 in this application may use the positive electrode single-sided region 110b or the positive electrode empty foil area for termination.

[0080] The positive electrode double-sided region 110a and the positive electrode single-sided region 110b refer to two coating regions sequentially arranged along the length of the positive electrode sheet 110. The positive electrode double-sided region 110a is used to form a double-sided active layer, and the positive electrode active layer 112 of the positive electrode single-sided region 110b is formed on the side of the positive electrode sheet 110 near the winding center of the cell 100. At least a portion of the positive electrode single-sided region 110b is disposed on the outermost layer of the cell 100 and serves as the tail structure of the cell 100. That is, the end of the positive electrode single-sided region 110b away from the positive electrode double-sided region 110a constitutes the winding termination end of the positive electrode sheet 110, so that this region directly exposes the positive electrode current collector 111 after winding.

[0081] In some other embodiments, the positive electrode sheet 110 also includes a positive electrode empty foil region. The positive electrode double-sided region 110a, the positive electrode single-sided region 110b and the positive electrode empty foil region are arranged adjacent to each other along the length direction of the positive electrode sheet 110. The positive electrode empty foil region and part of the positive electrode single-sided region 110b can be wound together on the outermost layer of the cell 100.

[0082] The following embodiments illustrate the use of a positive electrode single-sided region 110b for the termination of the battery cell 100, but this does not constitute an absolute limitation on the termination method of the positive electrode sheet 110. The positive electrode tab 113 includes a first positive electrode tab 1131 led out from the positive electrode current collector 111 of the positive electrode single-sided region 110b and a second positive electrode tab 1132 led out from the positive electrode current collector 111 of the positive electrode double-sided region 110a. After the positive electrode sheet 110 is wound, the two tabs can be aligned in the thickness direction of the battery cell 100 to be gathered and connected to form a positive electrode tab group 113'.

[0083] The number of first positive tabs 1131 can be at least one, and the number of second positive tabs 1132 can be two or more, in order to improve the fast charging performance of the battery.

[0084] In related technologies, multiple second positive tabs 1132 are led out from the positive current collector 111 of the positive double-sided region 110a to transmit current. In contrast to related technologies, the solution in this embodiment also leads out a first positive tab 1131 from the positive current collector 111 of the positive single-sided region 110b. The positive tab group 113' is formed by stacking and closing the first positive tab 1131 and the second positive tab 1132. The first positive tab 1131 can be bound by the positive single-sided region 110b located on the outermost layer of the cell. This can reduce the risk that the positive tab group 113' in related technologies is prone to deformation and contact with the edge of the negative electrode sheet 130 during drop tests due to lack of binding. The first positive tab 1131 can be located on the outermost or second outermost layer of the positive tab group 113'. The first positive tab 1131 can cover the second positive tab 1132. The first positive tab 1131 can fix the positive tab group 113', thereby preventing the positive tab group 113' from contacting the side of the negative electrode sheet 130 near the positive tab group 113' due to vibration and impact when the battery is dropped. This helps to reduce the risk of battery short circuit and improve the battery's drop resistance. In a preferred embodiment, the first positive tab 1131 is located on the outermost positive single-sided area of ​​the cell, that is, the first positive tab 1131 is located on the outermost layer of the positive tab group 113'.

[0085] Since the positive electrode single-sided region 110b is only coated on one side, after the positive electrode sheet 110 is rolled, the positive electrode active layer 112 will be embedded in the positive electrode current collector 111. Due to the reduction in the interparticle spacing of the positive electrode active layer 112, they generate repulsive forces against each other. In addition, due to the difference in elongation between the positive electrode active layer 112 and the positive electrode current collector 111, the positive electrode active layer 112 and the positive electrode current collector 111 will undergo asynchronous elongation deformation during the rolling of the positive electrode sheet. This difference in elongation causes the internal stress between the bonding surface of the positive electrode active layer 112 and the positive electrode current collector 111 and the side of the positive electrode current collector 111 that is not coated with the positive electrode active layer 112 to be different. This results in a difference in internal stress in the positive electrode single-sided region 110b, which in turn causes the positive electrode single-sided region 110b to curl. This internal stress will also act on the first positive electrode tab 1131, thereby causing the first positive electrode tab 1131 to shift into the inside of the cell 100, increasing the risk of short circuit in the battery.

[0086] To improve the problems of curling and offset of the positive electrode single-sided region 110b and the first positive electrode tab 1131, in this embodiment, the positive electrode single-sided region 110b includes a first region 1101b. The first region 1101b includes a plurality of protrusions and recesses corresponding to the protrusions. The recesses are disposed on the side surface of the first region 1101b facing the winding center of the battery cell 100, and the protrusions are disposed on the side surface of the first region 1101b away from the winding center of the battery cell 100. The recesses are recessed from the side of the first region 1101b close to the winding center of the battery cell 100 toward the side away from the winding center of the battery cell 100, and the protrusions are raised from the side of the first region 1101b close to the winding center of the battery cell 100 toward the side away from the winding center of the battery cell 100.

[0087] Thus, the concave and convex portions allow the positive current collector 111 to undergo pre-deformation, appropriately increasing its elongation. They also dissipate some of the stress generated inside the positive electrode single-sided region 110b after rolling the positive electrode sheet 110, while simultaneously forming a reverse internal stress opposite to the direction of the curling internal stress. This resists bending deformation and improves the curling and offset problems of the positive electrode single-sided region 110b and the first positive electrode tab 1131. Furthermore, the concave and convex portions on the positive electrode single-sided region 110b create a certain curvature, providing support and offsetting some of the stress caused by the bending of the positive electrode tab group 113'. This prevents the positive electrode tab group 113' from contacting the negative electrode sheet 130, thereby reducing the risk of short circuits when the battery is dropped.

[0088] The convex and concave portions are formed by local pressing, rolling, stamping or other methods through a roller pressing mechanism with a specific structure. The two portions correspond to each other in the thickness direction of the positive electrode single-sided region 110b, so as to adjust the elongation and force distribution of the positive electrode current collector 111 in the positive electrode single-sided region 110b.

[0089] Reference Figure 4 As shown, it should be noted that the positive electrode single-sided region 110b may also have a second region 1102b and a third region 1103b. The second region 1102b and the third region 1103b are located on opposite sides of the first region 1101b along the second direction. The second region 1102b is located closer to the positive electrode tab 113 than the third region 1103b. No concave or convex portions are provided on the second region 1102b and the third region 1103b. Since the convex portions are dispersed in the positive electrode single-sided region 110b, when determining the range of the first region 1101b, the area formed by the outermost edge of the multiple convex portions can be used to define the area where the first region 1101b is located, and then the area of ​​the first region 1101b can be calculated.

[0090] In some embodiments, the positive electrode single-sided region 110b may also include at least one of a fourth region and a fifth region, wherein the fourth region is located on one side of the first region 1101b along the first direction and is disposed away from the positive electrode double-sided region 110a, and the fifth region is located on one side of the first region 1101b along the first direction and is disposed close to the positive electrode double-sided region 110a.

[0091] The presence of convex and concave portions can improve the curling problem. However, due to the presence of convex portions, the positive electrode single-sided area 110b without concave and convex portions will fold towards the outside of the cell 100, or the area with convex portions will locally arch. That is, the two areas are subjected to different forces, resulting in uneven force on the entire positive electrode single-sided area 110b. This will generate a pulling force on the first positive electrode tab 1131. Furthermore, since the negative electrode sheet 130 is prone to expansion during cycling, expansion stress will be generated. The above-mentioned pulling force and expansion stress are superimposed, which will in turn increase the risk of contact between the positive electrode tab group 113' and the negative electrode sheet 130.

[0092] Therefore, the battery cell 100 in this embodiment is further provided with a first adhesive member 140 to reduce the problem of folding or local arching of the positive electrode single-sided region 110b after the concave and convex portions are provided on the positive electrode single-sided region 110b. The first adhesive member 140 is provided on the side surface of the positive electrode single-sided region 110b away from the winding center of the battery cell 100. The first adhesive member 140 covers the area where the concave and convex portions are located, and the overlapping area of ​​the first adhesive member 140 and the first region 1101b accounts for 2%-70% of the total area of ​​the first region 1101b.

[0093] It is understandable that, on the one hand, since the overlapping area of ​​the first adhesive 140 and the first region 1101b accounts for 2% or more of the total area of ​​the first region 1101b, the first adhesive 140 can at least cover a portion of the concave and convex parts, thereby improving the folding problem caused by the setting of concave and convex parts in the positive electrode single-sided region 110b, and thus preventing the positive electrode single-sided region 110b from squeezing the shell 200.

[0094] On the other hand, since the overlapping area of ​​the first adhesive 140 and the first region 1101b accounts for 70% or less of the total area of ​​the first region 1101b, the coverage area of ​​the first adhesive 140 on the positive electrode single-sided region 110b is not too large. After the positive electrode single-sided region 110b and the first adhesive 140 are wound together, the thickness of the cell 100 will be increased, thereby limiting the above-mentioned area ratio to below 70% to improve the volumetric energy density of the cell 100.

[0095] Furthermore, when the battery cell 100 is finished using the positive electrode single-sided region 110b, the first adhesive 140 is disposed on the surface of the positive electrode single-sided region 110b and forms a local fixed relationship with the positive electrode single-sided region 110b, thereby keeping the wound battery cell 100 in a predetermined shape and preventing the interface of the battery cell 100 from becoming loose.

[0096] When determining the ratio of the overlapping area of ​​the first adhesive 140 and the first region 1101b to the total area of ​​the first region 1101b, the battery can be discharged to 0% SOC and then disassembled. After the wound positive electrode sheet 110 is flattened, the overlapping dimension of the first adhesive 140 and the first region 1101b, as well as the dimension of the first region 1101b, are measured respectively. Then, by calculating the above-measured dimensions, the overlapping area S1 of the first adhesive 140 and the first region 1101b, and the total area S2 of the first region 1101b are obtained, and thus S1 / S2 is obtained.

[0097] For example, the first region 1101b can be rectangular. When measuring the size of the first region 1101b, the size of the first region 1101b in the length direction and width direction of the positive electrode 110 can be measured respectively, and the total area S2 of the first region 1101b can be calculated.

[0098] In some embodiments, the first adhesive 140 may be configured as a dotted, striped, sheet-like or intermittent adhesive form as required. The first adhesive 140 may be made of insulating adhesive paper, insulating adhesive layer, etc. The first adhesive 140 may be made of hot melt adhesive layer, pressure sensitive adhesive layer, adhesive film layer or local hot pressing curing layer, or may be an adhesive layer formed by dispensing and curing.

[0099] In one possible embodiment, the positive current collector 111 can be aluminum foil, the positive active layer 112 can be lithium cobalt oxide, doped and coated lithium cobalt oxide, lithium iron phosphate, or nickel-cobalt-manganese ternary material coating, the thickness of the positive active layer 112 can be adjusted according to the capacity requirements, the adjacent boundary between the positive double-sided region 110a and the positive single-sided region 110b along the length direction can be a continuous transition or a stepped transition, and the width and length of the positive electrode sheet 110 can be determined according to the design capacity of the cell 100.

[0100] During the winding process, the separator 120 is wound synchronously with the positive electrode 110 and the negative electrode 130 and is located between the positive electrode active layer 112 and the negative electrode active layer. The separator 120 can be a single-layer or multi-layer composite microporous membrane. The material can be a polyolefin, a ceramic-coated polyolefin, or a composite membrane with a heat-resistant reinforcing layer. The width of the separator 120 can be slightly larger than the width of the negative electrode 130 to form the necessary insulation margin at the edge.

[0101] The negative electrode current collector can be copper foil, and the negative electrode active layer can be graphite, artificial graphite, silicon-based composite material, or a mixture of graphite and silicon-based composite material. The negative electrode sheet 130 can also be provided with single-sided or double-sided coating areas. The negative electrode sheet 130 and the positive electrode sheet 110 are alternately stacked along the winding direction.

[0102] The battery provided in this application comprises a positive electrode 110, a separator 120, and a negative electrode 130 wound together to form a battery cell 100. A double-sided positive electrode region 110a and a single-sided positive electrode region 110b are arranged sequentially along the winding direction of the positive electrode 110. The double-sided positive electrode region 110a, located in the innermost layer, bears the main electrochemical reaction area, while the single-sided positive electrode region 110b, located in the outermost layer, forms an adhesive and shape-confining outer surface on its side away from the winding center of the battery cell 100. Multiple positive tabs 113 are led out from the single-sided positive electrode region 110b and the double-sided positive electrode region 110a, respectively, and are gathered together after the battery cell 100 is initially formed to form a group of positive tabs 113. These tabs are bent from the first surface 100a to the second surface 100b, so that the group of positive tabs 113 is folded and positioned on one side of the height direction of the battery cell 100. Since the first positive electrode tab 1131 is led out from the positive single-sided region 110b and the second positive electrode tab 1132 is led out from the positive double-sided region 110a, the first positive electrode tab 1131 and the second positive electrode tab 1132 are stacked. The second positive electrode tab 1132 can play the main role in transmitting current. The first positive electrode tab 1131 is formed on the outermost layer of the positive electrode tab group 113. Compared with the existing battery cell 100, which does not have a first positive electrode tab 1131 on the outermost positive single-sided region 110b, the first positive electrode tab 1131 is provided on the outermost positive single-sided region 110b of the battery cell 100. The tab 1131 can fix and limit the outermost first positive tab 1131, reducing the risk of the first positive tab 1131 shifting and deforming, thereby reducing the risk of it contacting the negative electrode 130. Thus, the first positive tab 1131 can fix the positive tab group 113, thereby preventing the positive tab group 113 from contacting the edge of the negative electrode 130 near the positive tab group 113 due to vibration and impact when the battery is dropped. This helps to reduce the risk of battery short circuit and improve the battery's drop resistance.

[0103] Because the positive electrode single-sided region 110b is provided with a first region 1101b, the first region 1101b is provided with a plurality of protrusions and corresponding concave portions. The concave portions are provided on the side surface of the positive electrode single-sided region 110b facing the winding center of the cell 100, and the protrusions are provided on the side surface of the positive electrode single-sided region away from the winding center of the cell 100. This can increase the ductility of the positive electrode current collector 111 of the positive electrode single-sided region 110b, thereby improving the tendency of the positive electrode single-sided region 110b to penetrate into the cell 100 due to single-sided coating. To address the issue of curling, the risk of the first positive tab 1131 shifting into the cell 100 due to curling of the positive electrode single-sided area 110b is reduced. After setting the concave and convex portions on the positive electrode single-sided area 110b, a certain curvature and pre-deformation are generated on the positive electrode single-sided area 110b, which can provide effective support for the positive electrode single-sided area 110b, thereby reducing the stress generated by the bending of the positive tabs 113 group. This can prevent short circuit problems caused by the positive tabs 113 group contacting the negative electrode sheet 130 during battery drops and cycles.

[0104] Since the first adhesive 140 is disposed on the side surface of the positive electrode single-sided region 110b away from the winding center of the cell 100, the first adhesive 140 can provide local reinforcement to the positive electrode single-sided region 110b. This can improve the local stress concentration caused by the presence of concave and convex portions in the positive electrode single-sided region 110b, which can lead to local breakage of the positive electrode sheet 110 and weaken its fixing effect on the first positive electrode tab 1131. It can also suppress excessive outward arching of the positive electrode single-sided region 110b during battery cycling after the presence of concave and convex portions, which could pull on the first positive electrode tab 1131 and increase the risk of the first positive electrode tab 1131 contacting the negative electrode sheet 130. The first adhesive 140 can also bind the concave and convex portions to prevent the formation of convex portions from causing the positive electrode sheet 110b to break. If the gap between the area of ​​the positive electrode single-sided region 110b without recesses and protrusions and the separator 120 is too large, it will cause poor adhesion. This will reduce the problem of warping and folding of the positive electrode single-sided region 110b without recesses and protrusions. The coverage of the first adhesive 140 is controlled within the range of 2%-70% as needed, thereby effectively suppressing the tendency of the positive electrode single-sided region 110b to warp, fold, or roll due to uneven force. This will maintain the insulation gap and structural fit relationship near the positive electrode tabs 113 group, and prevent the first adhesive 140 from increasing the thickness of the cell 100, or from absorbing too much electrolyte and causing dissolution. This will improve the volumetric energy density and cycle performance of the battery.

[0105] Thus, the battery in this embodiment can maintain a relatively stable state during cycle use, preventing short circuits caused by the positive tabs 113 coming into contact with the negative electrode 130 when the battery is dropped, and the battery has a high volumetric energy density and cycle performance.

[0106] Reference Figure 2 and Figure 9 As shown, in some embodiments, the first positive electrode tab 1131 includes a first sub-positive electrode tab 11311. The positive electrode single-sided region 110b connected to the first sub-positive electrode tab 11311 is disposed closer to the second surface 100b than the first surface. For example, the positive electrode single-sided region 110b connected to the first sub-positive electrode tab 11311 can be directly formed as the second surface 100b, or the positive electrode single-sided region 110b connected to the first sub-positive electrode tab 11311 can be formed as a layer adjacent to the second surface 100b and located on the side of the second surface 100b near the winding center.

[0107] The first positive electrode tab 11311 includes a first stacked segment 11311a and a first connecting segment 11311b connected to the first stacked segment 11311a. The connection between the first stacked segment 11311a and the first connecting segment 11311b forms a first bending point 11311c. Relative to the bottom wall of the first pit, the first bending point 11311c is closer to the bottom wall of the second pit. Along the second direction, the distance T between the edge of the negative electrode 130 near the first bending point 11311c and the first bending point 11311c satisfies: 0.2mm≤T≤2mm.

[0108] It is understood that the first stacked segment 11311a is the portion of the first sub-positive electrode tab 11311 that is adjacent to the positive current collector 111 and is formed by bending from the first surface 100a toward the second surface. The first connecting segment 11311b is the portion of the first sub-positive electrode tab 11311 that is connected to the first stacked segment 11311a and extends from the second surface toward the first surface 100a. The first bending point 11311c is the portion of the first sub-positive electrode tab 11311 that is located near the second surface and connects the first stacked segment 11311a and the first connecting segment 11311b. When bending the first sub-positive electrode tab 11311, the first sub-positive electrode tab 11311 is bent once with the first bending point 11311c as the reference. That is, the first bending point 11311c can be considered as the bending vertex of the first sub-positive electrode tab 11311 near the second surface 100b.

[0109] In the second direction, the distance T from the first bending point 11311c to the side edge of the negative electrode 130 near the first bending point 11311c can be considered as the minimum distance from the bending point 1133' to the side edge of the negative electrode 130 near the first bending point 11311c. If the distance T from the first bending point 11311c to the side edge of the negative electrode 130 near the first bending point 11311c meets the requirement, then the distance from the bending point 1133' to the side edge of the negative electrode 130 near the first bending point 11311c also meets the requirement.

[0110] The distance T from the first bending point 11311c to the edge of the negative electrode 130 is limited to between 0.2mm and 2mm. Since the distance T is greater than or equal to 0.2mm, the minimum distance between the bending point 1133' and the edge of the negative electrode 130 is ensured. This ensures that even if the positive electrode tabs 113' undergo slight displacement under conditions of cyclic expansion, vibration, shock, or temperature rise and contraction after the first positive electrode tab 1131 is bent, they are unlikely to cross the safety gap and contact the edge of the negative electrode 130, thus reducing the risk of short circuit in the battery. Since the distance T from the first bending point 11311c to the edge of the negative electrode 130 is less than or equal to 2mm, the positive electrode tabs 113' are prevented from occupying excessive space in the first direction, thereby increasing the volumetric energy density. In this way, both volumetric energy density and insulation safety margin can be balanced.

[0111] In specific settings, when the size of the battery cell 100 is small, T can be close to the lower limit to improve space utilization, while when the thickness of the battery cell 100 is large or the cyclic expansion is significant, T can be close to the upper limit to improve safety.

[0112] In some embodiments, the width of the first positive tab 1131 is greater than the width of the second positive tab 1132. When the width of the first positive tab 1131 is greater than the width of the second positive tab 1132, the first positive tab 1131 can have a larger conductive cross-sectional area and higher mechanical load-bearing capacity. The first positive tab 1131 can withstand greater local stress during winding, bending and subsequent welding processes, thereby effectively fixing multiple second positive tabs 1132, thus ensuring a safe gap between the positive tab group 113' and the negative electrode 130. Furthermore, the first positive tab 1131 can provide a more stable current collection path when externally connected, thereby reducing the risk of overheating caused by excessively high local current density or insufficient overcurrent area.

[0113] In some embodiments, the first positive electrode tab 1131 further includes a second sub-positive electrode tab 11312, and the positive electrode single-sided region 110b connected to the second sub-positive electrode tab 11312 is disposed close to the first surface 100a. That is, the first sub-positive electrode tab 11311 and the second sub-positive electrode tab 11312 are respectively led out from the positive current collectors 111 on opposite sides of the thickness direction of the cell 100.

[0114] When the first positive electrode tab 1131 also includes a second sub-positive electrode tab 11312, the second sub-positive electrode tab 11312 can be understood as belonging to the same group as the first sub-positive electrode tab 11311 and used to fix the second positive electrode tab 1132. Its function is to lead out the first positive electrode tab 1131 from the positive electrode single-sided region 110b on both sides of the thickness direction of the cell 100, and arrange the electrode tab positions of the positive electrode single-sided region 110b near the first surface 100a and the second surface 100b of the cell 100 respectively. The second sub-positive electrode tab 11312 can form an upper and lower distributed combination with the first sub-positive electrode tab 11311. After winding, they are all located on the outermost layer of the positive electrode tab group 113', thereby clamping the multiple second positive electrode tabs 1132 in the middle, and thus fixing the multiple second positive electrode tabs 1132.

[0115] The width of the second positive electrode tab 11312 can be the same as the width of the first positive electrode tab 11311, and the width of the second positive electrode tab 11312 and the width of the first positive electrode tab 11311 are both greater than the width of the second positive electrode tab 1132.

[0116] Thus, by introducing the second positive electrode tab 11312 and setting its corresponding positive electrode single-sided region 110b close to the first surface 100a, the positive electrode tab group 113' forms a more stable structure after bending, and maintains a safe gap between the positive electrode tab group 113' and the negative electrode sheet 130 under cyclic expansion, external vibration or mechanical impact, thereby improving the safety of the battery.

[0117] In some embodiments, the positive electrode single-sided region 110b includes a first region 1101b and a second region 1102b connected to the first region 1101b. Recesses and protrusions are formed in the first region 1101b. The positive electrode sheet 110 also includes an insulating coating 114, which is located on the side of the first region 1101b near the first positive electrode tab 1131. The insulating coating 114 is formed on the positive current collector 111 in the second region 1102b and extends to at least a portion of the surface of the first positive electrode tab 1131.

[0118] In this embodiment, the first region 1101b is a functional region in the positive electrode single-sided region 110b used to adjust the local stress distribution. The first region 1101b changes the extensibility and stress distribution of the region by forming concave and convex portions, so as to reduce the curling of the positive electrode single-sided region 110b and the local folding problem caused by the setting of concave and convex portions when the cell 100 is wound, expanded or subjected to external impact. The second region 1102b is an adjacent region that continuously transitions to the first region 1101b. The second region 1102b can be understood as the region of the positive electrode single-sided region 110b near the first positive electrode tab 1131 and without concave and convex portions. The insulating coating 114 can be disposed on the positive electrode current collector 111 of the second region 1102b. The insulating coating 114 can isolate the positive electrode sheet 110 from the negative electrode sheet 130 of the adjacent winding layer, thereby reducing the risk of contact between the positive electrode sheet 110 and the negative electrode sheet 130, thereby reducing the risk of battery short circuit. Furthermore, since the insulating coating 114 extends to the root of the first positive electrode tab 1131 near the positive current collector 111, it can improve the rigidity of the first positive electrode tab 1131, thereby improving the bending resistance of the root of the first positive electrode tab 1131. It can also play a certain role in resisting the displacement deformation of the positive electrode tab group 113', preventing the positive electrode tab group 113' from being too close to the edge of the negative electrode sheet 130 and increasing the risk of short circuit.

[0119] Along the first direction, the thickness of the insulating coating 114 is less than the thickness of the positive electrode active layer 112. This ensures that the insulating coating 114 does not increase the overall thickness of the positive electrode sheet 110, thereby helping to maintain the compactness of the battery cell 100 and reduce its volume. The insulating coating 114 is a coating formed by mixing ceramic and polymer materials. The ceramic material includes at least one of alumina, boehmite, silicon dioxide, titanium dioxide, and zirconium oxide. The polymer material includes a polymer formed by copolymerizing at least one of the monomers selected from methyl methacrylate, ethyl methacrylate, isooctyl acrylate, n-propyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, styrene, butadiene, methacrylamide, acrylamide, acrylonitrile, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, and hexafluoropropylene.

[0120] Along the second direction, the width of the insulating coating 114 located in the second region 1102b is less than or equal to the width of the second region 1102b. Thus, since the width of the insulating coating 114 is not greater than the width of the second region 1102b, its coverage is limited by the boundary of the second region 1102b. This satisfies the local insulation requirements of the positive electrode 110 without excessively encroaching on the space where the positive electrode active layer 112 is disposed on the positive electrode 110, thereby preventing the battery energy density from being excessively reduced.

[0121] Thus, in the battery of this embodiment, the recesses and protrusions on the first region 1101b can be used to adjust the extensibility of the positive current collector 111 of the positive electrode single-sided region 110b, making the outermost positive electrode single-sided region 110b less prone to curling, warping, or folding when expanding, contracting, or subjected to external forces. Furthermore, the second region 1102b and its insulating coating 114 provide insulation protection near the first positive electrode tab 1131. As the first positive electrode tab 1131 is stacked, bent, and positioned, the insulating coating 114 can adhere to at least a portion of its surface, preventing the first positive electrode tab 1131 from contacting the adjacent negative electrode sheet 130.

[0122] Since the width of the insulating coating 114 is constrained by the boundary of the second region 1102b and its thickness is less than that of the positive electrode active layer 112, the insulating coating 114 provides insulation performance without significantly increasing the local thickness of the positive electrode single-sided region 110b or significantly changing the spatial layout of the positive electrode tab 113 after bending, so as to ensure the energy density of the battery.

[0123] It should be noted that, referring to Figure 4 As shown, the insulating coating 114 can be disposed on one side of the width direction of the positive electrode 110 and on the same side as the positive electrode tab 113. The insulating coating 114 can extend along the length direction of the positive electrode 110 to the positive double-sided region 110a to prevent the positive electrode 110 and the negative electrode 130 from contacting each other and causing a short circuit.

[0124] In some embodiments, the protrusion height H1 of the protrusion is between 1 μm and 60 μm. Preferably, the protrusion height H1 of the protrusion is between 1 μm and 40 μm. And / or, the thickness H2 of the first adhesive 140 is between 10 μm and 30 μm. And / or, the ratio of the protrusion height of the protrusion to the thickness of the first adhesive 140 is between 0.04 and 5. And / or, the width of the protrusion is between 0.1 mm and 3 mm; and / or, the distance between two adjacent protrusions is between 1 mm and 10 mm.

[0125] For example, the protrusion height H1 of the protrusion can be any one of 1μm, 2μm, 5μm, 8μm, 10μm, 20μm, 25μm, 30μm, 40μm, 45μm, 50μm, 55μm, and 60μm, or fall within any two of these values. The thickness H2 of the first adhesive 140 can be any one of 10μm, 15μm, 20μm, 22μm, 25μm, 28μm, and 30μm, or fall within any two of these values. The ratio of the protrusion height of the protrusion to the thickness of the first adhesive 140 can be any one of 0.04, 0.04, 0.1, 0.2, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.5, 3, 3.2, 3.5, 4, and 4.5, or fall within any two of these values. The width of the protrusion can be any one of 0.1mm, 0.2mm, 0.3mm, 0.5mm, 1mm, 1.5mm, 2.5mm, or 3mm, or fall within any two of these values. The distance between two adjacent protrusions can be any one of 1mm, 1.2mm, 2mm, 3mm, 6mm, 8mm, or 10mm, or fall within any two of these values.

[0126] When the protrusion height of the convex portion is less than 1 μm, it cannot effectively improve the ductility of the positive current collector 111 in the positive electrode single-sided region 110b, nor can it effectively dissipate the internal stress of the positive electrode single-sided region 110b, thus failing to improve the curling problem of the positive electrode single-sided region 110b. Conversely, when the protrusion height of the convex portion is greater than 60 μm, it may lead to excessively large local protrusions, causing local stress concentration, increasing the risk of local fracture in the positive electrode single-sided region, reducing the binding effect on the first positive electrode tab, and also reducing the thickness uniformity of the positive electrode single-sided region 110b, or increasing the risk of local folding in the positive electrode single-sided region 110b. Therefore, when the protrusion height of the convex portion is between 1 μm and 60 μm, a microtexture structure sufficient to generate stress adjustment can be formed on the surface of the positive electrode single-sided region 110b without excessively weakening the flatness and mechanical strength of the positive electrode single-sided region 110b.

[0127] When the thickness of the first adhesive 140 is between 10μm and 30μm, a relatively stable first adhesive 140 can be formed to press down the protrusions and concave parts, thereby preventing the deformation tendency of the positive electrode single-sided region 110b. This effectively improves the folding and arching problems caused by the protrusions and concave parts, ensuring the adhesive force while avoiding the formation of local thick areas on the positive electrode single-sided region 110b due to the first adhesive 140 being too thick.

[0128] When the ratio of the protrusion height of a single protrusion to the thickness of the first adhesive 140 is between 0.04 and 5, it indicates that the protrusion height of the protrusion and the thickness of the first adhesive 140 can be matched to achieve stress compensation under different expansion amounts and fixing requirements. The first adhesive 140 also effectively improves the adverse effects of setting the protrusion.

[0129] When the width of a single protrusion is between 0.1mm and 3mm, it is beneficial to increase the number of protrusions per unit area, and avoid the problem that the protrusions are too large and cause local large protrusions in the positive electrode single-sided area 110b, or prevent the size of a single micro protrusion in the positive electrode single-sided area 110b from being too small to achieve pre-deformation.

[0130] When the distance between two adjacent protrusions is between 1mm and 10mm, the protrusions can be distributed within a reasonable density range while ensuring overall continuity and processing feasibility. This avoids the problem of excessive density reducing the strength and structural stability of the positive electrode single-sided region 110b, or insufficient support due to excessively sparse protrusion arrangement.

[0131] Thus, since the height, width and spacing of the protrusions meet the preset range with the thickness of the first adhesive 140, local support, adhesive retention and stress release can achieve a coordinated balance. This avoids the thickening of the winding layer caused by the first adhesive 140 being too thick, and also avoids edge folding or local stress concentration in the positive electrode single-sided area 110b caused by the protrusions being too high or too dense.

[0132] Additionally, it should be noted that the height H1 of the protrusion of the positive electrode single-sided region 110b can be measured using the following test method: A sample of the positive electrode single-sided region 110b to be tested is obtained from the finished battery. After cleaning and drying the sample, it is observed under an optical microscope or scanning electron microscope. The microscope magnification is adjusted to a suitable magnification that allows clear differentiation of the individual morphology of the protrusions, for example, 500x to 2000x. Along the length of the positive electrode single-sided region 110b, using the surface of the positive electrode active layer 112 without concave or convex portions as a reference plane, the vertical distance from the reference plane to the apex of the protrusion is measured; this distance is the height of the protrusion. Multiple positive electrode single-sided regions 110b from different areas on the positive electrode sheet 110 can be taken as test samples. For each sample, the height of the protrusions in at least 50 different areas is measured. Then, the arithmetic mean of the heights of the different protrusions is taken as the final value H1 of the protrusion of the positive electrode single-sided region 110b.

[0133] Reference Figure 2 , Figure 7 and Figure 8As shown, in some embodiments, the battery further includes a first adapter, and the first adhesive 140 includes a first sub-adhesive 141. At least a portion of the first adapter overlaps and connects with the positive electrode tab group 113' to form an adapter portion, and at least a portion of the first sub-adhesive 141 covers the at least a portion of the adapter portion. At least a portion of the first sub-adhesive 141 covers the first positive electrode tab 1131. At least a portion of the first sub-adhesive 141 covers the surface of the positive electrode single-sided region 110b on the side facing away from the winding center of the cell 100.

[0134] In this embodiment, the first adapter is a conductive structure used to collect the current from multiple positive tabs 113 and lead it outward. The first adapter can form a stable mechanical and electrical connection with the positive tab group 113' through welding, pressing, bonding, or other methods, thereby constituting an adapter part. The first adapter can be disposed on the outside of the connecting section 1132' after the positive tab group 113' is bent, and the first adapter can extend out of the housing 200 to connect with an external circuit.

[0135] For example, multiple positive tabs 113 can be gathered together and connected into a positive tab group 113' by ultrasonic welding. The positive tab group 113' is then laser- or ultrasonically welded to the first adapter, so that the current of the positive electrode 110 is transmitted to the external circuit through the positive tab group 113' and the first adapter.

[0136] The first sub-adhesive 141 can be used to cover and fix a local surface of the positive electrode tab 113, the first adapter, or the positive electrode single-sided region 110b. For example, when the first sub-adhesive 141 covers the adapter, the first sub-adhesive 141 can constrain and protect the solder marks on the adapter to prevent burrs on the solder marks from damaging other structures.

[0137] The first sub-adhesive 141 can be disposed on the adapter portion and can extend further to the first positive electrode tab 1131 to partially cover the first positive electrode tab 1131. The first sub-adhesive 141 can also extend further to the side surface of the positive electrode single-sided area 110b away from the winding center of the cell 100, so that the first adhesive 140 can bond and fix the adapter portion, the first positive electrode tab 1131 and the positive electrode single-sided area 110b, thereby protecting the adapter portion and fixing the first positive electrode tab 1131, thereby preventing the position of the positive electrode tab group 113' from shifting and contacting the negative electrode sheet 130 when the battery is dropped.

[0138] Alternatively, the first sub-adhesive 141 can be designed in segments, with part of the first sub-adhesive 141 attached to the adapter, part of the first sub-adhesive 141 attached to the first positive electrode tab 1131, and part of the first sub-adhesive 141 attached to the surface of the positive electrode single-sided area 110b facing away from the winding center of the cell 100.

[0139] The first adapter can be any one of aluminum sheet, nickel sheet, composite busbar or multilayer laminated sheet, and the first sub-adhesive 141 can be any one of insulating tape, heat-resistant film, pressure-sensitive adhesive layer, dispensing curing adhesive layer, composite protective paper or local hot-pressing bonding layer.

[0140] Thus, the positive electrode group 113' overlaps with the first adapter and forms an adapter section through welding or pressing. Current from different positive electrodes 113 is collected by this adapter section and output to the external circuit. When the first sub-adhesive 141 covers the adapter section, it can cover the welding area or the pressing area to protect the adapter section. When the first sub-adhesive 141 covers the first positive electrode 1131, it can form an additional constraint on the bent first positive electrode 1131, thereby constraining the positive electrode group 113' to fix the positive electrode group 113', which helps to maintain a safe gap between the positive electrode group 113' and the negative electrode plate 130. When the first sub-adhesive 141 covers the surface of the positive electrode single-sided region 110b away from the winding center of the cell 100, it can also cover the protrusion on the positive electrode single-sided region 110b, thereby suppressing the curling, warping or folding tendency of the positive electrode single-sided region 110b, thus maintaining the structural stability of the cell 100.

[0141] Reference Figure 1 As shown, in one possible implementation, in the second direction, the overlap dimension L between the first sub-adhesive 141 and the positive electrode single-sided region 110b is between 1 mm and 8 mm. For example, the overlap dimension L can be any one of 1 mm, 2 mm, 3 mm, 5 mm, 6 mm, or 8 mm, or fall within any two of these values.

[0142] When the first sub-adhesive 141 is attached to the surface of the positive electrode single-sided region 110b away from the winding center of the cell 100, it forms an effective overlap of 1mm to 8mm with the positive electrode single-sided region 110b in the height direction of the cell 100. As the cell 100 undergoes volume changes during charge and discharge cycles, as well as external vibrations and impact loads, the first sub-adhesive 141 can continuously press the area with its own adhesive force to buffer stress, thereby reducing the occurrence of deformation problems such as curling and warping at the edge of the positive electrode single-sided region 110b. This reduces the risk of the positive electrode single-sided region 110b pulling the first positive electrode tab 1131 after deformation, and reduces the possibility of the first positive electrode tab 1131 contacting the adjacent negative electrode sheet 130.

[0143] Since the overlap size between the first sub-adhesive 141 and the positive electrode single-sided region 110b is limited to the aforementioned range, the first sub-adhesive 141 can cover local areas sensitive to structural stability, thereby improving the curling and folding problems of the positive electrode single-sided region 110b, without extensively obscuring the surface of the positive electrode single-sided region 110b to prevent increasing the overall thickness of the positive electrode single-sided region 110b. Furthermore, it can cooperate with the bending structure of the positive electrode lugs 113' to fix the positive electrode lugs 113', making the gap between the positive electrode lugs 113' and the negative electrode sheet 130 more stable, reducing the risk of contact between the positive electrode lugs 113' and the negative electrode sheet 130 due to local deformation of the positive electrode single-sided region 110b.

[0144] Reference Figure 3 , Figure 4 and Figure 7 As shown, in one possible embodiment, the first adhesive 140 further includes a second sub-adhesive 142, which is connected to the end of the positive electrode single-sided region 110b opposite to the positive electrode double-sided region 110a.

[0145] In other words, the second sub-adhesive 142 can fix the tail end of the positive electrode single-sided region 110b to prevent the interface of the wound cell 100 from becoming loose. Furthermore, since the second sub-adhesive 142 also covers the concave and convex portions, it can constrain the positive electrode single-sided region 110b, thereby improving the folding and arching problems caused by the setting of concave and convex portions.

[0146] Reference Figure 7 and Figure 8 As shown, in one possible embodiment, the first adhesive 140 further includes a third sub-adhesive 143, which is located on opposite sides of the positive electrode tab 113 along the second direction.

[0147] Thus, the first sub-adhesive 141 and the third sub-adhesive 143 can be respectively disposed on both sides of the positive electrode single-sided region 110b along the second direction, and cover at least a portion of the first region 1101b, so as to constrain one side edge of the positive electrode single-sided region 110b along the second direction by the first sub-adhesive 141, and constrain the other side edge of the positive electrode single-sided region 110b along the second direction by the third sub-adhesive 143, so as to prevent the positive electrode single-sided region 110b from folding or warping on the opposite sides along the second direction due to the presence of concave and convex portions.

[0148] Reference Figure 7 and Figure 8As shown, in one possible embodiment, the battery cell 100 includes a flat region and an arc region, with two arc regions formed on both sides of the flat region along a third direction. The first adhesive member 140 also includes a fourth sub-adhesive member 144, which is disposed on at least one arc region. The first direction, the second direction, and the third direction are perpendicularly arranged. The third direction can be the width direction of the battery cell 100, specifically referring to the Z direction in the accompanying drawings.

[0149] Understandably, since the positive electrode single-sided area 110b located on the arc area is curved, and the positive electrode single-sided area 110b also has concave and convex parts, coupled with the expansion stress of the negative electrode sheet 130, its stress state is more complex and more prone to stress concentration. Therefore, a fourth sub-adhesive 144 can be set on the outer side of the two arc areas to improve the stress situation of the positive electrode single-sided area 110b in this area, thereby preventing local breakage, folding or wrinkling of the positive electrode single-sided area 110b in this area, so as to ensure its binding effect on the first sub-positive electrode tab 11311, thereby reducing the risk of short circuit when the first sub-positive electrode tab 11311 contacts the edge of the negative electrode sheet 130.

[0150] Reference Figure 3 and Figure 4 As shown, in one possible embodiment, the first adhesive 140 further includes a fifth sub-adhesive 145. The fifth sub-adhesive 145 is disposed at one end of the positive electrode single-sided region 110b near the positive electrode double-sided region 110a, and covers the junction of the positive electrode double-sided region 110a and the positive electrode single-sided region 110b. This is to cover the stepped structure formed by the abrupt change in thickness at the junction of the positive electrode double-sided region 110a and the positive electrode single-sided region 110b by the fifth sub-adhesive 145. Since the fifth sub-adhesive 145 covers the concave and convex portions, the stepped structure caused by the concave and convex portions and the stress concentration in the surrounding area can be reduced.

[0151] It should be understood that since the first adhesive component 140 includes one or more of the first sub-adhesive component 141, the second sub-adhesive component 142, the third sub-adhesive component 143, the fourth sub-adhesive component 144, and the fifth sub-adhesive component 145, when calculating the overlap area S1 between the first adhesive component 140 and the positive electrode single-sided region 110b, any overlap between the first sub-adhesive component 141, the second sub-adhesive component 142, the third sub-adhesive component 143, the fourth sub-adhesive component 144, and the fifth sub-adhesive component 145 and the first region 1101b should be included in S1.

[0152] Reference Figure 2As shown, in one possible implementation, the battery cell 100 further includes a second adhesive member 150, which is disposed along a second direction on the side of the positive tab 113 near the positive current collector 111. Along a first direction, the second adhesive member 150 is disposed between two adjacent positive tabs 113 along the thickness direction of the battery cell 100 to connect the two adjacent positive tabs 113, and / or, the second adhesive member 150 is located on the surface of the first positive tab 1131 facing away from the second positive tab 1132.

[0153] After the winding and bending of the positive tab 113, the positive tab group 113' forms a partially stacked structure on the side near the positive current collector 111. The second adhesive 150 is located near the positive current collector 111 along the second direction and spans between adjacent positive tabs 113 along the first direction, or is attached to the surface of the first positive tab 1131 facing away from the second positive tab 1132. The adhesive force of the second adhesive 150 itself is used to constrain the positive tabs 113 connected to it, thereby preventing the multiple positive tabs 113 of the positive tab group 113' from becoming loose and preventing the positive tab group 113' from deforming and contacting the negative electrode sheet 130.

[0154] Thus, as the cell 100 expands in the thickness direction during charging and discharging, or generates slight vibrations under external impact, the second adhesive 150 can absorb some stress and distribute the load, thereby reducing the probability of the positive electrode tab 113 being displaced due to local stress, and thus preventing short circuits caused by the positive electrode tab 113 contacting the negative electrode sheet 130.

[0155] In some embodiments, at least a portion of the projection of the second adhesive 150 along the first direction is located between the bending point 1133' and the edge of the positive electrode 110 near the positive electrode tab 113.

[0156] Since the second adhesive 150 is located on the side close to the positive current collector 111, it occupies less space and can maintain the overall shape consistency of the positive electrode tab group 113' while ensuring the stability of the conductive connection path. Therefore, it helps to improve the structural stability of the positive electrode tab group 113' under long-term cycling and vibration shock conditions, as well as the safety and reliability of the battery.

[0157] The projection of the second adhesive 150 along the first direction is defined on the side of the bending point 1133' closer to the negative electrode 130. In other words, the coverage area of ​​the second adhesive 150 in the thickness direction of the cell 100 is preferentially arranged on the side with a higher potential short-circuit risk. The second adhesive 150 is located within the space between the laminated section 1131' and the negative electrode 130, so as to form insulation between the negative electrode 130 and the laminated section 1131' without significantly increasing the overall thickness of the cell 100, thus providing structural support for the laminated section 1131' and preventing short circuits caused by contact between the laminated section 1131' and the negative electrode 130. Furthermore, if the bending point 1133' of the second adhesive 150 is located away from the negative electrode 130, after the positive electrode tabs 113' are bent, the folded state of the positive electrode tabs 113' is easily unstable, resulting in a rebound, which is detrimental to maintaining the structural stability of the positive electrode tabs 113'.

[0158] The second adhesive component 150 can be an adhesive layer, a dotted adhesive block, or a partially applied flexible adhesive film. The material can be heat-resistant insulating adhesive, modified acrylic adhesive, polyimide composite tape, or a light-cured adhesive layer after irradiation, such as UV adhesive.

[0159] In some embodiments, the negative electrode 130 includes a negative electrode current collector and a negative electrode active layer disposed along its own thickness direction, and a plurality of negative electrode tabs extending from one side of the negative electrode current collector in the width direction. The thickness of the positive electrode current collector 111 is greater than the thickness of the negative electrode current collector. And / or, the number of positive electrode tabs 113 is greater than the number of negative electrode tabs.

[0160] For example, the negative electrode current collector can be made of copper foil, copper alloy foil, or surface-plated copper foil, and the negative electrode active layer can be made of graphite, silicon carbide, hard carbon, or their composite materials, and formed by slurry coating, rolling, and drying processes. The current collector of the negative electrode sheet 130 can lead out multiple negative electrode tabs, which can be made of copper tabs, nickel tabs, copper-nickel composite tabs, etc. The multiple negative electrode tabs are spaced apart along the same edge of the negative electrode current collector, so that after the negative electrode sheet 130 is wound, the multiple negative electrode tabs are correspondingly arranged along the thickness direction of the cell 100, so as to be gathered and welded to form a negative electrode tab group.

[0161] Because the thickness of the positive current collector 111 is greater than that of the negative current collector, the positive electrode sheet 110 can achieve higher structural support and better welding load-bearing capacity, avoiding local stress concentration during bending, stacking, or cyclic expansion. The positive electrode tab 113 is integrally formed with the positive current collector 111, ensuring that the thickness of the positive current collector 111 is greater than that of the negative current collector. This also allows the positive electrode tab 113 to maintain a certain strength, preventing it from breaking after bending and increasing the risk of contact with the negative electrode sheet 130. Furthermore, the number of positive electrode tabs 113 is greater than the number of negative electrode tabs. The positive electrode sheet 110 can disperse the bus resistance and solder joint impedance through more tab outlets, thereby reducing the current density and heat borne by a single positive electrode tab 113 and improving connection reliability. This increases the structural stability of a single positive tab 113, reduces the risk of fatigue cracking of a single positive tab 113, and enables the cell 100 to maintain a relatively stable internal resistance growth trend and a relatively stable structural morphology under long-term cycling and high-rate conditions, thereby reducing the risk of short circuits caused by the displacement and deformation of the positive tab group 113', which is beneficial to improving the cycle life and safety performance of the battery.

[0162] In this embodiment, during the winding assembly of the battery cell 100, the negative electrode 130, the separator 120, and the positive electrode 110 are alternately stacked and wound in a predetermined order. The negative electrode active layer undertakes the lithium-ion insertion and extraction reactions during charging and discharging, while the negative electrode current collector gathers the electrons generated by the negative electrode active layer to multiple negative electrode tabs and conducts them outwards. Because the negative electrode current collector is relatively thin, while the positive electrode current collector 111 is relatively thick, the positive electrode 110 has stronger resistance to deformation during the processing of protrusions and concave areas, as well as during cyclic expansion, preventing localized overvoltage problems in the positive electrode 110.

[0163] The following is a brief description of the battery preparation process and related tests in Example 1.

[0164] I. Preparation of Positive Electrode 110

[0165] Lithium cobalt oxide (LCO), polyvinylidene fluoride (PVDF), and conductive agent (Super P) are dissolved in N-methylpyrrolidone (NMP) in a ratio of 97.6:1.05:1.35 and stirred evenly to form a slurry. The slurry is then uniformly coated onto aluminum foil, with some aluminum foil being coated on both sides and others on one side. After drying, rolling, and die-cutting, an integral structure of positive electrode tab 113 and positive electrode current collector 111 is formed. The positive electrode tab 113 includes a first positive electrode tab 1131 and a second positive electrode tab 1132. The positive electrode single-sided area 110b is embossed with an embossing roller to form concave and convex portions. The fifth sub-adhesive 145 is attached to the junction of the positive electrode double-sided area 110a and the positive electrode single-sided area 110b and extends onto the positive electrode single-sided area 110b.

[0166] II. Preparation of negative electrode 130

[0167] Silicon-carbon composite material, graphite, conductive carbon black, sodium carboxymethyl cellulose, and styrene-butadiene rubber are mixed in a ratio of 15:80.8:1.2:1.0:2.0. After being mixed with deionized water and stirred evenly to form a slurry, the slurry is uniformly coated on both surfaces of a copper foil. After drying and rolling, a negative electrode sheet 130 is formed. Then, after die-cutting and slitting, multiple negative electrode tabs are die-cut to obtain an integrated structure of multiple negative electrode tabs 500 and a negative current collector. The number of negative electrode tabs is less than the number of positive electrode tabs 113.

[0168] III. Battery Assembly

[0169] The positive electrode 110, separator 120, and negative electrode 130 are stacked and wound together, with the positive electrode 110 having a single-sided positive electrode region 110b as its winding termination end. A second sub-adhesive 142 is attached to the end of the single-sided positive electrode region 110b that is away from the double-sided positive electrode region 110a. Multiple positive electrode tabs 113 are gathered and welded together to form a positive electrode tab group 113'. Multiple negative electrode tabs are gathered and welded together to form a negative electrode tab group. A first sub-adhesive 141 is attached to the side of the single-sided positive electrode region 110b that is close to the positive electrode tab group 113'. The first sub-adhesive 141 covers part of the surface of the first positive electrode tab 1131 and the adapter portion formed by the overlapping connection of the first adapter and the positive electrode tab group 113'. The battery is obtained by sequentially performing processes such as encapsulation, liquid injection, secondary sealing, formation, and sorting.

[0170] Unlike Example 1, Example 6 does not have a first sub-adhesive 141, while Examples 7, 8, and Comparative Example 5 all have a third sub-adhesive 143 and a fourth sub-adhesive 144. Comparative Example 1 does not have a first positive electrode tab 1131, and the positive electrode single-sided area 110b does not have a concave or convex portion. Comparative Example 2 does not have a first positive electrode tab 1131. Comparative Example 3 does not have a concave or convex portion in the positive electrode single-sided area 110b. Comparative Example 4 does not have a first sub-adhesive 141. Other differences between Examples 2 to 10, and Comparative Examples 1 to 5 and Example 1 can be found in Table 1.

[0171] It should be understood that, since the first adhesive 140 includes one or more of a first sub-adhesive 141, a second sub-adhesive 142, a third sub-adhesive 143, a fourth sub-adhesive 144, and a fifth sub-adhesive 145, in various embodiments and comparative examples, the variation of the overlap area S1 between the first adhesive 140 and the first region 1101b can be achieved by designing the overlap area between one or more of the first sub-adhesive 141, the second sub-adhesive 142, the third sub-adhesive 143, the fourth sub-adhesive 144, and the fifth sub-adhesive 145 and the first region 1101b.

[0172] For example, when S1 in Embodiment 2 is the same as S1 in Embodiment 1, in Embodiment 1, the overlapping area of ​​the fifth sub-adhesive 145 and the first region 1101b can be slightly larger, and the overlapping area of ​​the second sub-adhesive 142 and the first region 1101b can be slightly smaller. In Embodiment 2, the overlapping area of ​​the fifth sub-adhesive 145 and the first region 1101b can be slightly smaller, and the overlapping area of ​​the second sub-adhesive 142 and the first region 1101b can be slightly larger.

[0173] Table 1 Battery parameters

[0174]

[0175] Volumetric energy density test:

[0176] Test method: Charge the battery to 4.5V at a 0.2C current, then charge it at a constant voltage until the current drops to 0.02C. Discharge it to 3.0V at a 0.2C current, and record the energy discharged as E. Measure the battery's thickness, width, and length, and calculate their product to obtain the battery's volume, recorded as V. The formula for calculating the volumetric energy density VED is VED = E / V.

[0177] Drop test:

[0178] Test method: Under an environment of 25℃±5℃, the battery is discharged at 0.2C to the lower limit voltage, left to stand for 10 minutes, then charged at 1C to the upper limit voltage, with a cutoff current of 0.02C, and left to stand for 10 minutes. The fully charged battery is then dropped freely from a height of 1 meter onto a concrete or metal floor at 25℃. The test is considered passed if the battery does not ignite or explode. A total of 3 tests are conducted. 20 batteries are tested in each group.

[0179] Cyclic capacity retention:

[0180] Test method: The batteries obtained in the above examples and comparative examples were left to stand at 25°C for 30 minutes, discharged to 3V at 0.5C, fully charged according to the specifications (generally 1C), discharged 3 times at 0.2C, and the maximum capacity was taken as the initial discharge capacity at 0.2C; discharged to 3V at 0.2C, fully charged according to the specifications (generally 1C), discharged 3 times at 0.5C, and the average value of the three discharge capacities was taken as the initial capacity at 1C.

[0181] The cycle conditions are as follows: charge at a constant current of 1.5C to 4.3V (voltage cutoff), then charge at a constant current of 1.2C to 4.45V (voltage cutoff), then charge at a constant current of 1C to 4.53V (voltage cutoff), and finally charge at a constant current and constant voltage of 0.8C to 4.58V (cutoff current 0.05C). Then discharge at 1C to 3V and record the discharged capacity as the capacity for this cycle. Let the device rest for 5 minutes between each charge and discharge step.

[0182] The above cycle conditions are repeated 800 times. The discharge capacity of the 800th cycle is divided by the initial capacity and then multiplied by 100% to obtain the battery's 800T cycle capacity retention rate.

[0183] Table 2 Battery Test Results

[0184]

[0185] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A battery, characterized in that, include: A battery cell, comprising a positive electrode, a separator, a negative electrode, and a first adhesive element, wherein the positive electrode, the separator, and the negative electrode are wound together, the positive electrode includes a positive current collector and a positive active layer disposed on at least one side surface of the positive current collector, and the positive electrode also includes a plurality of positive tabs extending from one side of the positive current collector in the width direction and integrally connected with the positive current collector, wherein the plurality of positive tabs are gathered together and connected to form a positive tab group; The battery cell includes a first surface and a second surface disposed opposite to each other along a first direction. The positive electrode group includes a stacked segment formed by bending from the first surface to the second surface and a connecting segment connected to the stacked segment. Along the second direction, the connecting segment is located on the side of the stacked segment away from the positive current collector. The positive electrode sheet includes a positive electrode double-sided region and a positive electrode single-sided region adjacent to each other along its own length direction. In the positive electrode double-sided region, the positive electrode active layer is formed on opposite two sides of the positive electrode current collector in the thickness direction. In the positive electrode single-sided region, the positive electrode active layer is formed on one side of the positive electrode current collector facing the winding center of the battery cell. At least a portion of the positive electrode single-sided region is disposed on the outermost layer of the battery cell. The positive electrode tab includes a first positive electrode tab and a second positive electrode tab, at least one of the first positive electrode tabs is led out from the positive current collector of the outermost positive single-sided region of the battery cell, and the second positive electrode tab is led out from the positive current collector of the positive double-sided region; The positive electrode single-sided region includes a first region having a plurality of recesses and protrusions. The first region includes a plurality of protrusions and recesses corresponding to the plurality of protrusions. The recesses are disposed on the side surface of the first region facing the winding center of the battery cell, and the protrusions are disposed on the side surface of the first region away from the winding center of the battery cell. At least a portion of the first region is disposed on the outermost layer of the battery cell. The first adhesive is disposed on the side surface of the positive electrode single-sided area away from the winding center of the cell. At least a portion of the first adhesive overlaps with at least a portion of the first area, and the overlapping area of ​​the first adhesive and the first area accounts for 2%-70% of the total area of ​​the first area.

2. The battery according to claim 1, characterized in that, The connection between the stacked segment and the connecting segment forms a bending point. The first positive electrode tab includes a first sub-positive electrode tab. The positive electrode single-sided area connected to the first sub-positive electrode tab is disposed close to the second surface. The first positive electrode tab includes a first stacked segment and a first connecting segment connected to the first stacked segment. The connection between the first stacked segment and the first connecting segment forms a first bending point. Along the second direction, the distance T between the edge of the negative electrode sheet near the first bending point and the first bending point satisfies: 0.2mm≤T≤2mm.

3. The battery according to claim 1, characterized in that, The width of the first positive electrode tab is greater than the width of the second positive electrode tab; And / or, the first positive electrode tab also includes a second sub-positive electrode tab, and the positive electrode single-sided region connected to the second sub-positive electrode tab is disposed close to the first surface.

4. The battery according to claim 1, characterized in that, The positive electrode single-sided region further includes a second region connected to the first region. The second region is located on one side of the first region along the second direction and is disposed close to the positive electrode tab. The positive electrode sheet further includes an insulating coating. The insulating coating is formed on the positive electrode current collector in the second region and extends to at least a portion of the surface of the first positive electrode tab. Along the second direction, the width of the insulating coating located in the second region is less than or equal to the width of the second region; Along the first direction, the thickness of the insulating coating is less than the thickness of the positive electrode active layer.

5. The battery according to claim 4, characterized in that, The protrusion height of the protrusion is between 1 μm and 60 μm; And / or, the thickness of the first adhesive is between 10 μm and 30 μm; And / or, the ratio of the protrusion height of the protrusion to the thickness of the first adhesive is between 0.04 and 5; And / or, the width of the protrusion is between 0.1 mm and 3 mm; And / or, the distance between two adjacent protrusions is between 1 mm and 10 mm.

6. The battery according to claim 1, characterized in that, It also includes a first adapter, at least a portion of which overlaps with and connects to the positive electrode group to form an adapter portion, and the first adhesive includes a first sub-adhesive. At least a portion of the first sub-adhesive covers the surface of the positive electrode single-sided region on the side opposite to the winding center of the cell; In the second direction, the overlap between the first sub-adhesive and the positive electrode single-sided area is between 1 mm and 8 mm.

7. The battery according to claim 1, characterized in that, The first adhesive and at least a portion of the positive electrode single-sided region are both disposed on the outermost layer of the cell, and the end of the positive electrode single-sided region facing away from the positive electrode double-sided region constitutes the winding termination end of the positive electrode sheet. The first adhesive component further includes a second sub-adhesive component, which is connected to one end of the positive electrode single-sided region that is opposite to the positive electrode double-sided region; And / or, the first adhesive member further includes a third sub-adhesive member, the third sub-adhesive member being located on opposite sides of the positive electrode tab along the second direction; And / or, the battery cell includes a flat region and an arc region, with two arc regions formed on both sides of the flat region along a third direction, and the first adhesive further includes a fourth sub-adhesive disposed on at least one of the arc regions.

8. The battery according to claim 1, characterized in that, The first adhesive also includes a fifth sub-adhesive, which covers the boundary between the positive electrode double-sided region and the positive electrode single-sided region.

9. The battery according to claim 2, characterized in that, It also includes a second adhesive element, which is disposed between two adjacent positive tabs along the second direction to connect the two adjacent positive tabs; And / or, the second adhesive is located on the surface of the first positive electrode tab away from the second positive electrode tab; And / or, the projection of the second adhesive member along the first direction is located between the bending point and the edge of the positive electrode sheet near the positive electrode tab.

10. The battery according to claim 1, characterized in that, The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer arranged along its own thickness direction, as well as a plurality of negative electrode tabs led out from one side of the negative electrode current collector in the width direction; The thickness of the positive current collector is greater than the thickness of the negative current collector; And / or, the number of positive tabs is greater than the number of negative tabs.

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